Displays

Pits from fruit like apricots, peaches and cherries are an under-utilized resource. If there is any use at all, they may be extracted for special vegetable oils. Mostly the pits are combusted or left to rot. However, they are also an appropriate feedstock for pyrolytic carbonization. This study investigated the biochar produced from apricot pits for its potential to sorb phosphate from liquid media and from artificial wastewater.

Shredded apricot pits were pyrolyzed at 450 °C in a lab-scale screw reactor (Pyreka 3.0). Additionally, the impregnation of the feedstock with Mg(OH)₂ before pyrolysis was studied to test the hypothesis that phosphate sorption to biochar takes advantage of metal bridges on the biochar surface.

The results of isotherm sorption experiments showed that the pre-pyrolysis Mg-surface modification of the pits improved the sorption capacity of the biochar up to 42 mg PO₄-P/g whereas the unmodified biochar adsorbed only about one tenth. When KH₂PO₄ was used as the only sorbate, EDX-mapping showed the formation of K-struvite-crystals in the pores of the biochar. Desorption experiments showed a major release of the adsorbed phosphate within a few hours. Sorption competition experiments with phosphate and nitrate showed no negative effect of nitrate on phosphate sorption. Feedstock impregnation with Ca(OH)₂ resulted in more variable sorption dynamics.

The results could be confirmed by deploying the surface-modified apricot pit biochar for the reduction of the phosphate load in artificial wastewater.

How to cite: Soja, G., Wyhlidal, S., Friesl-Hanl, W., Zwölfer, K., Edlinger, J., Reis, C., and Gattringer, H.: Surface-modified apricot pits as biochar feedstock and phosphate sorbent, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3924, https://doi.org/10.5194/egusphere-egu2020-3924, 2020.

The emergence of micropollutants, such as pharmaceuticals in wastewater, presents a potential risk for human health as well as the aquatic environment. Current wastewater treatment plants are generally not capable of removing these pollutants without additional treatment steps. Adsorption on activated carbon is an effective way to remove these contaminants, however, the use of non-renewable feedstocks as well as low regeneration efficiencies increase the environmental costs of this method¹. Biochar as a renewable carbon platform material can be specifically designed to overcome these drawbacks².

This study is aimed at designing activated mineral biochar composites with enhanced adsorption capacity for pharmaceuticals while simultaneously optimising their regeneration performance. Two standard biochars from the UK Biochar Research Centre produced at 550°C from softwood and wheat straw were activated in CO₂ at 800°C. Additionally, activated mineral biochar composites were produced by the addition of ochre – a Fe-rich mining waste – prior to pyrolysis and activation.

The activated biochars and activated mineral biochar composites were analysed for their maximum adsorption capacity for two micropollutants - caffeine and fluconazole - and compared to a commercial activated carbon as a reference material. While the activated carbon outperformed all biochar samples, the addition of ochre increased the performance of the activated biochar samples. The regeneration performance was tested in a subsequent experiment. The materials were first loaded with a mix of 10 pharmaceuticals covering antibiotics, fungicides and antidepressants. The loaded biochars were then subjected to a novel regeneration method directly utilising wet adsorbents in contrast to common methods requiring prior drying. Similar to a powerful pressure cooker, solvolytic conversion conditions of water at temperatures ranging from 160 to 320°C and elevated pressures of 15 to 120 bar were used to regenerate the biochars. Hydrothermal treatment at 320°C was found to successfully degrade the adsorbed micropollutants across all biochars. The mineral biochar composites showed increased pollutant degradation most likely due to the catalytic effects of Fe in hydrothermal conditions, lowering the necessary treatment temperature to 280°C.

The results show that while designing biochar for certain applications, a simultaneous focus on both the application as well as the regeneration of the material can give a more comprehensive picture of the overall requirements for further optimisation of biochar adsorbents.

1. Thompson, K. A. et al. Environmental Comparison of Biochar and Activated Carbon for Tertiary Wastewater Treatment. Environ. Sci. Technol. (2016). doi:10.1021/acs.est.6b03239
2. Liu, W. J., Jiang, H. & Yu, H. Q. Development of Biochar-Based Functional Materials: Toward a Sustainable Platform Carbon Material. Chem. Rev. 115, 12251–12285 (2015).

How to cite: Wurzer, C., Oesterle, P., Jansson, S., and Masek, O.: A parallel optimisation of adsorption and regeneration properties of activated biochars for wastewater treatment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-858, https://doi.org/10.5194/egusphere-egu2020-858, 2020.

Biochar is a versatile soil additive and CO₂ neutral or negative “green” sorbent. Biochar can improve the soil quality, water retention capacity, and is effective in binding contaminants. Previous studies showed that biochar is a suitable remediation option at sites with residual contamination and that it is particularly favorable in immobilizing organic polycyclic aromatic hydrocarbons (PAHs) and cadmium. To achieve remediation goals, however, careful assessment of the soil geochemistry (pH, background ions, organic carbon content), the nature of the contaminant, and the application rate need to be carried out. We have screened the sorption affinity of 11 different types of biochars and 2 activated carbons for selected heavy metals and ionizable and non-ionizable PAHs. The biochars differed in the starting feedstock material (rice husk, wheat straw pellets, mixed softwood pellets, oil seed rape straw, miscanthus straw pellets), temperature of production (550°C, 700°C), and elemental composition. The target contaminants included acenaphthene, dibenzofuran, carbazole, dibenzothiophene, 2-hydroxybiphenyl, cadmium, and mercury. The sorption of the organic contaminants was driven by the carbon content, specific surface area, and aromatic nature of the biochars. Sorption of cadmium was higher onto biochars with greater inorganic fractions, whereas for mercury no specific trends could be observed. Based on the results of the initial screening, a novel approach to statistically design experiments using the Box-Behnken model was employed for selected biochars. Using this method, experiments were conducted to systematically investigate the influence of four factors (pH, dissolved organic carbon, ionic strength and contaminant concentration) on sorption at three different levels (-1, 0, +1). The results from the surface response modeling approach provides fundamental new insight into the applicability of these biochars at contaminated sites and can help identify scenarios favorable for remediation with biochar. Our results will help in the development of a remediation strategy with an overall low environmental footprint for contaminated soils.

How to cite: Chaudhuri, S., Sigmund, G., von Rautenkranz, H., Hueffer, T., and Hofmann, T.: Factors influencing the sorption of polycyclic aromatic hydrocarbons, cadmium and mercury to biochars – a surface response methodology approach, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3897, https://doi.org/10.5194/egusphere-egu2020-3897, 2020.

Oxidized biochar from plant biomass (OBPM) was used to remove caffeine (CF) from aqueous solutions. Among examined parameters that affect adsorption, pH was found to play the most important role. By increasing the initial pH from 2 to 4, the adsorption capacity of CF was increased, whereas for pH above 4, a decline of the adsorption efficiency was noticed. The effect of contact time was also investigated in the range of 1 – 150 minutes and results indicated that the adsorption process consists of two steps. The initial step was relatively fast most probably, because a large number of adsorption surface sites was available, and with proceeding contact time the adsorption rate declined. The latter could be attributed to the decreasing number of vacant sites and to the development of repulsive forces between the free CF molecules and the occupied OBPM surface. The experimental data were best fitted by the pseudo-second order kinetic, compared to pseudo-first order kinetic model and the Freundlich isotherm model better fitted the data. The raise of temperature from 25 to 50 °C affected negatively the CF removal, indicating the exothermicity of the adsorption. Finally, FTIR spectroscopic data and investigations on the effect of ionic strength indicated that the adsorption mechanism is mainly based on electrostatic interactions and the formation of outer sphere surface complexes.

How to cite: Anastopoulos, I., Pashalidis, I., and Robalds, A.: Removal of caffeine by oxidized biochar, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3937, https://doi.org/10.5194/egusphere-egu2020-3937, 2020.

In drained boreal peatlands, forest regeneration is typically done using a sequence of clear-cutting, ditch network maintenance, site preparation and planting. Following the forest regeneration, export of nutrients to water courses is increased. This results in degradation of water quality, eutrophication, and enhances the formation of harmful algal blooms. The aim of current research was to test a biochar reactor in forest runoff water purification, especially nitrogen recovery from runoff water. The biochar reactor was tested using a meso-scale laboratory experiment by circulating forest runoff water through biochar-filled columns and by monitoring water nutrient concentrations in the inlet and outlet of the columns. Adsorption rate (K_ad) and maximum adsorption capacity (Q_max) were quantified by fitting pseudo-first and second order as kinetic models to the experimental data. The results demonstrated that concentration of total nitrogen (TN) decreased by 58% during the 8 weeks experiment, and the majority of TN adsorption has occurred already within the first 3 days. In addition, NO₃-N and NH₄-N concentrations decreased below the detection limit in 5 days after the beginning of the experiment. The results demonstrated that the biochar reactor was not able to adsorb TN in low concentrations. The results suggest that biochar reactor can be a useful and effective method for runoff water purification in clear-cut forests and deserves further development and testing. This makes biochar reactor a promising water protection tool to be tested in sites where there is a risk for high rate of nutrient export after forest regeneration.

Keywords: adsorption, biochar reactor, column experiment, inorganic nitrogen, total nitrogen.

How to cite: Kakaei Lafdani, E., Saarela, T., Laurén, A., Pumpanen, J., and Palviainen, M.: Column experiment for purification of clear-cut forest runoff using biochar, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13598, https://doi.org/10.5194/egusphere-egu2020-13598, 2020.

The objective of this study was to produce regular and Graphene Oxide (GO) coated biochar adsorbents, using two types of biomass as feedstock, i.e. Rice Husks (RH) and Sewage Sludge (SS), in two pyrolytic temperatures (400°C and 600°C). The produced adsorbents were thoroughly characterized in terms of physicochemical properties, where biochars produced from RH at 600°C showed the most favourable results. Specifically, the S_BET values of these samples were up to four times higher compared to biochars produced at 400°C and up to thirteen times higher, compared to the respective SS biochars. Moreover, the metal content of the samples was determined, in order to assess their safety, where all values were under the limits set by the European Union. Finally, biochars were tested as adsorbents for the removal of six organic micro-pollutants, i.e. 2,4-Dichlorophenol (2,4D), Bisphenol A (BPA), Androsterone (ADT), Norethindrone (NOR), Estrone (E1) and Ethinyl Estradiol (EE2), from table water and wastewater, in low (realistic) initial concentrations. The pollutants were successfully adsorbed by biochar, in rates of 40%-97.5% for the RH biochars and 10%-97.5% for the RH biochars, in 1h. GO-enriched RH biochars produced at 600°C were the most effective adsorbents, removing the pollutants in rates higher than 70%, in just 10min of adsorption time.

How to cite: Regkouzas, P. and Diamadopoulos, E.: Adsorption of six organic micro-pollutants from water and wastewater using Graphene Oxide-coated biochars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13728, https://doi.org/10.5194/egusphere-egu2020-13728, 2020.

Superabsorbent hydrogels (SAHs) are three-dimensional cross-linked polymeric network, with the ability to absorb large quantities of water (or other fluids), keep their network stable even in the swollen state and  release the water in response to specific environmental stimuli. In last decades, several SAHs have been developed and studied for their potential to improve soil physical properties for agricultural purposes, e. g. by increasing their ability to retain water, increasing the efficiency of water use, increasing the absorption capacity or promoting the uptake of nutrients by the plant. Although various studies have shown that SAHs can contribute to soil microstructural stability and improve soil-water interactions in general, the specific impact of water content on the hydrogel effect in soil remains largely unclear. Specifically, the SAH effects needs to be inquired in dynamic water content conditions.

The aim of this study was to evaluate how the water content affects soil-water-hydrogel interactions in different soils (i.e. sandy, loamy and silty soils). Two different SAHs were studied, a polyacrylamide and a self-made cellulose-based SAH added with humic acids. Untreated and SAH-treated (4 mg g⁻¹) samples were analysed for soil water retention and unsaturated hydraulic conductivity coupling the Wind method (−1 to −80 kPa) with WP4-T dew point (-3000 to 15000 kPa). SAH deswelling dynamic was evaluated measuring the sample volume change from −1 to −7 kPa potential. Volume was measured reconstructing the 3D shape of the soil sample employing a 3D Point Cloud Reconstruction software.

Soil-SAH mixtures changed the water retention characteristics if compared to the controls. SAHs significantly increased the water entrapment and altered the pore-size distribution according to the soil types. It can be hypothesized that in the soil-SAH mixtures there was a texture-dependent rearrangement of soil particles, depending on the various interactions between hydrogel structures and soil constituents as a function of water content. These findings demonstrated the potential of SAHs to advantageously modify the soil hydraulic characteristics, but also showed that further studies are needed to better comprehend the behaviour of hydrogels in dynamic water content conditions in different soils.

How to cite: Camarotto, C., Pozza, S., Piccoli, I., Guerrini, G., and Morari, F.: Studying hydraulic characteristics of three soils amended with superabsorbent hydrogels, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7011, https://doi.org/10.5194/egusphere-egu2020-7011, 2020.

Higher Education in England targets to reduce by an average 34% carbon dioxide emissions until 2020 based on the level in 1990. This project not only requires various departments of universities to improve their energy system by utilizing low carbon techniques but also challenges the academics and researchers to examine multiple approaches to sequester carbon as much as possible in the limited area. Land owned by universities contains a lot of carbon. The group SUCCESS (Sustainable Urban Carbon Capture Engineering Soils for Climate Change) in Newcastle University has observed that 10 ha of urban soil near Newcastle Science Central removed almost 80 T CO₂ per hectare every month.

The project has set up two lysimeters in June 2018 to investigate the addition of wheat straw pellets (WP) versus biochar (BC) produced from this biomas as carbon sequestration strategies. Sensors were set up at different depths to collect information about the internal soil environment. The wheat straw biochar has 69.04% C content, and it was applied to the soil at a rate of 2% (w/w); the application rate of wheat straw pellets is based on the carbon weight of wheat straw biochar. Therefore, the amount of carbon added as wheat straw pellets, or as wheat straw biochar was 29.8±0.57 Kg in each lysimeter.

Cumulatively, 704.23±0.14 g and 697.17±0.1 g of total carbon were leached from the lysimeter BC and lysimeter WP, respectively, till the end of November 2019. Meanwhile, the total amount of CO2 carbon released via respiration of soil carbon was 9.65±0.35 Kg and 6.17±0.19 Kg for lysimeter BC and lysimeter WP, respectively, from August 2018 to November 2019. Moreover, the carbon mass fixed, measure as dried grass biomass in the two systems was 1.57 Kg for lysimeter BC and 1.75 Kg for lysimeter WP. The net C mass stored according to the mass balance for the lysimeter BC is 21.02 ±0.67 Kg from the topsoil during the experiment period, and 24.68±0.6 Kg in lysimeter WP. Whereas, by measurement, the amount of carbon in the topsoil has shown an increase of 37.09±13.58 Kg and 19.51±3.36 Kg in lysimeter BC and lysimeter WP, respectively. Currently, the data obtained in this study indicate that the mixture of biochar and biomass amendment promotes carbon sequestration potential in the urban soil environment and further application details on land owned by the university can be explored.

How to cite: Wang, J., Werner, D., and Manning, D.: Assessing the potential of urban soil for carbon sequestration by adding wheat straw pellets or wheat straw biochar, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18735, https://doi.org/10.5194/egusphere-egu2020-18735, 2020.

The former sewage field south of Berlin are contaminated with heavy metals due to decades of wastewater irrigation. Since the abandonment of irrigation, the pH values have decreased and the accumulated organic substance mineralized, so that the mobility of the heavy metals increased and the plant-available zinc and copper contents reach concentrations critical for plant growth.

In 2011, biochar was added to immobilize the heavy metals as part of a field trial. On samples aged in the field with 0 and 5% biochar, we examined the change in the binding form of copper and zinc using the sequential extraction procedure according to Zeien and Brümmer (slightly changed) after eight years of field exposure.

As to copper, the plots with 5% biochar addition tended to have lower concentrations as a percentages of the total contents in fractions I-III (I mobile, II easy to supply, III bound to Mn oxides) compared to the plots without biochar addition. In fractions IV and V (IV organically bound, V bound to poorly crystalline Fe oxides) no clear differences could be found. In fractions VI and VII (VI bound to crystalline Fe oxides and VII residual), the plots with 5% biochar showed significantly higher percentages of copper. In samples with biochar addition from 2011, changes in the copper binding form were not clearly ascertainable. For zinc, only fractions I and II decreased significantly after 8 years of field exposure in the plots exposed to biochar. No clear changes could be seen in all other fractions. These effects were also present directly after biochar addition. Therefore, biochar appears to be a suitable additive to immobilize zinc and, in the long run, especially copper.

Further studies on the remobilization of copper and zinc on biochar particles separated from the aged field samples are currently running and can probably also be presented.

How to cite: Wagner, A., Müller, A., and Kaupenjohann, M.: Change in the binding form of copper and zinc in sewage field soil by addition of biochar after eight years of field exposure, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21764, https://doi.org/10.5194/egusphere-egu2020-21764, 2020.

The lack of clean water and waste generation are problems that exist in many parts all over the world. Different industries: electroplating, smelting and alloying could discharge cadmium pollutants into water body. Cadmium as toxic metal must be properly removed from wastewaters because it may lead to: kidney damage, respiratory insufficiency, hypertension, cancer, gastrointestinal disorder and osteoporosis.

Globally depletion of natural and nonrenewable resources has induced need for application of renewable sources in environment protection practices; such as renewable biomass. Biosorption has emerged as an economically feasible alternative for the environment cleanup using naturally occurring, abundant, waste biomass. Application of biosorbents in the form of powder have difficulties associated with their powder properties, indicating need for suitable form with adequate mechanical strength (e.g. beads) for easily manipulation and further use in flow systems.

The waste biomass which is tested as biosorbent of cadmium is cosmopolitan invasive aquatic weed - waste Myriophyllum spicatum immobilized as beads in natural polymer matrix-alginate – (MsA-B). M.spicatum grows on five continents and based on its widely negative effects on the environment in the whole world, this weed has been categorized as Category 1 Weed. M.spicatum used for preparation of beads originates from Sava Lake (Belgrade, Serbia) where it is regularly harvested by public company "Ada Ciganlija”. Ratio M. spicatum and alginate in beads is 2:1.

This biosorbent (MsA-B) was characterized by Scanning-Electron-Microscopy-EnergyDispersive-X-Ray-Spectroscopy (SEM-EDX). EDX spectra showed: Ca, Mg, Na, K and Cl. Large amount of calcium originate from the water environment in which this aquatic weed lives. The surface of (MsA-B) is different from the surface of aquatic weed because the alginate covered the characteristic rectangular openings. The beads are not spherical, but more ovoid shape. The surface is wrinkled and clearly layered. After Cd(II) sorption, reduced peaks of Ca as well as a new peak of Cd(II) are observed

The effect of the Cd(II) concentration on adsorption was studied at pH 5.0 in the concentration range from 20 to 750 mg/L as batch biosorption tests with 2 g/L MsA-B. Experimental results were fitted by six isotherm models: Langmuir, Freundlich, Sips, Redlich and Peterson, Toth, Temkin. After biosorption experiments, beads didn’t change its shape, size or colour. They have been easily separated from the solution by decanting. Comparison of models was made on the basis of the coefficients of determination R² and comparison value of biosorption capacities experimented and calculated by models. Order of best fit isotherm models: RP>L>S>Th>T>F. MsA-B showed high capacity for Cd(II) removal q=82,5 mg/g which is 33% higher capacity then capacity of dry biomass M.spicatum. During the biosorption experiments with MsA-B, changes of pH were insignificant. That is very important because there is no need to control pH, no demand for chemicals which greatly simplifies the process and makes it cheaper. Easy application and manipulation, much easier than other biosorbents simplify further investigations and applications of this aquatic weed beads – MsA-B in industrial wastewaters and also in the next step of the biosorption processes: flow systems and reactors.

Acknowledgement
These results are part of the projects supported by the Ministry of Education and Science of the Republic of Serbia, TR 31003. Jelena Milojković is grateful to the public company "Ada Ciganlija" (Belgrade, Serbia) for providing samples of aquatic weed M. spicatum. 

How to cite: Milojković, J., Lopičić, Z., Kojić, M., and Petrović, M.: Removal cadmium ions from aqueous solution by biosorbent - immobilized aquatic weed M. spicatum, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1091, https://doi.org/10.5194/egusphere-egu2020-1091, 2020.

Annually, large amounts of rice husk (>80 million tonnes) are produced around the world and high quantities of them are produced by developing countries. Determination of chemical and physical properties of new materials produced from the activation of rice husk biochars such as density, ash, surface area, surface topography, surface functional groups and suspension pH could affect sorption capacity and catalyst properties. In this study, biochars (RH), produced from raw rice husk (RAW-RH) at 850^oC through pyrolysis process, were activated with H₂O (W-RH), H₂SO₄ (RH-S), H₃PO₄ (RH-P), and NaOH (RH-ALK) and their physicochemical parameters were analysed.  This study aims to characterize the surface area and the porosity, the suspension pH, and the functional groups observed on the surface of RAW-RH, RH, W-RH, RH-S, RH-P, and RH-ALK. The determination of the surface area, the pore volume and the average pore size was performed by using gas (N₂) adsorption−desorption with the Micromeritics TriStar 3000 Analyzer system using the Brunauer, Emmett, and Teller (BET) equation. Before analysis, the RAW-RH was degassed at 60^oC under mild nitrogen flow for 1 h and RHs were degassed at 300^oC under mild nitrogen flow for 1 h. The results were recorded by Micromeritics TriStar 3000 software. The t-plot for the RHs disclosed that the activation with NaOH leads to high specific surface (938 m²/g) and micropore area (588 m²/g) compared to other RH samples (367-386 m²/g). Simultaneously, the activation of RH increases the pore size of biochar and the highest pore size was observed for the RH-ALK (51 Å) compared to activated RH-S and RH-P (48 Å). This can be attributed to the silica removal from RAW-RH by alkaline solution that creates a mesoporous material which is more suitable as a catalyst support for bulky reactants. RAW-RH presents various peaks on its surface corresponding to different functional groups. During the high pyrolysis temperature (850^oC) most of these peaks either disappear or begin to diminish and only few new peaks appear. Furthermore, RAW-RH has more acidic behavior than the other samples (pH 6.0). For the activated RH, RH-S and RH-P are slightly acidic materials (pH~6.2) and RH-ALK and W-RH are both slightly alkaline (pH~8.5). To conclude, activation with alkali solution creates a more desirable sorbent material since it increases the surface area by 260% compared to activation with acidic solutions which increases the surface area by ~5%.

Acknowledgment

We acknowledge support of this work by the project “Research Infrastructure on Food Bioprocessing Development and Innovation Exploitation – Food Innovation RI” (MIS 5027222), which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).

How to cite: Mourgkogiannis, N., Nikolopoulos, I., Kordouli, E., Kordulis, C., Lycourghiotis, A., and Karapanagioti, H. K.: Rice husk biochar activation and its effects on the characteristics of the final products to be used as sorbents or catalysts support, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8556, https://doi.org/10.5194/egusphere-egu2020-8556, 2020.

Microalgae are a group of microorganisms capable to accumulate up to 80% triacylglycerol w/w, making them as one of the most promising renewable sources for biofuels. Biodiesel derived from algal oil is produced via transesterification process, where the oil is mixed with alcohol and a suitable catalyst at an elevated temperature. Recently, research has been focused on catalysts from renewable sources, like biomass and residues generated in households, in the form of biochar. Biochar is obtained from the incomplete combustion of carbon-rich biomass under oxygen-limited conditions. The aim of this work is to investigate the use of biochar as a heterogeneous catalyst for the conversion of algal lipid into biodiesel. Selected algal strains were cultivated and lipids were extracted. The effect of feedstock and pyrolysis temperature were investigated.  More specifically, biochar was produced from malt spent rootlets, coffee spent grains and olive kernels at pyrolysis temperatures ranging from 300 to 850^oC. The materials produced were fully characterized for their surface characteristics such as BET surface area, pore and micropore volume, thermogravimetric analysis and point of zero charge. The preliminary results showed that biochar from malt spent rootlets achieved about 50% conversion of lipids to fatty acid methyl esters during transesterification.

How to cite: Tsavatopoulou, V. D., Aravantinou, A., Vakros, J., and Manariotis, I. D.: Biochar from different feedstocks as catalysts for the conversion of algal lipid into biodiesel , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19912, https://doi.org/10.5194/egusphere-egu2020-19912, 2020.

Coffee is considered the most widely spread beverage and annually, approximately, 11 billion tons are produced all around the world. Raw spent coffee residue (Raw-SCG), biochar coffee residue (SCG), and the activated biochar with distilled H₂O (W-SCG), H₂SO₄ (SCG-S), H₃PO₄ (SCG-P), and NaOH (SCG-ALK) were fully characterized for their surface area, density, ash, surface topography, surface functional groups and suspension pH. These are parameters that could affect sorption capacity and catalyst properties. In this study, Raw-SCG, obtained from a coffee shop in the campus of Patras University, was pyrolyzed at 850^oC in a custom-made ceramic saggar box. BET surface area of biochar consists a basic characteristic that controls its nutrient and pollutant sorption capacity. SCGs produced at 850^oC have high specific surface and micropore area and at the same time, low external surface area. The t-plot for the SCG disclosed that the activation with H₃PO₄ leads to high specific surface (921 m²/g) and micropore (626 m²/g) area compared to other SCG samples. Simultaneously, the activation of SCG increases the pore size of biochar and the highest pore size was observed for the SCG-ALK (37 Å) compared to activated SCG-S (34 Å) and SCG-P (34 Å). The Raw-SCG has slightly acidic nature (pH 5.5) than the biochar SCG (pH 10.6) which has the most alkaline nature. For the activated SCG biochars, SCG-S (pH 4.6) is more acidic than SCG-P (pH 5.2). Furthermore, W-SCG biochar (pH 9.1) is more alkaline than SCG-ALK (pH 8.8). A plethora of possible explanations can be given for the alkaline nature of biochar, such as the removal of acidic groups, but this is still under investigation. Moreover, the five samples present a peak at 1050 cm^-1 that corresponds to (C-O) bond and a weak peak at 3450 cm^-1 that reveals O-H groups. For the Raw-SCG, a carboxyl stretching mode (C=O) demonstrate a weak peak at 1740 cm^-1; the sharp peaks at 2830 and 2950 cm^-1 are related to aliphatic C-H₂ bending. The presence of a shallow peak at 2450 cm^-1 corresponds to CO₂ bond for the SCG and W-SCG. It is very important to mention that the peaks of W-SCG and SCG-ALK are similar. The results indicates that biochars SCG produced at 850^oC are acidic in nature, they are highly porous materials with micropores corresponding to the majority of pore volume and the activated SCG-P shows a rapid increase of micropore area compared to other activated and washed biochars (SCG-S, SCG-ALK, W-SCG). 

Acknowledgment

We acknowledge support of this work by the project “Research Infrastructure on Food Bioprocessing Development and Innovation Exploitation – Food Innovation RI” (MIS 5027222), which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).

How to cite: Mourgkogiannis, N., Nikolopoulos, I., Kordouli, E., Kordulis, C., Lycourghiotis, A., and Karapanagioti, H. K.: Spent coffee grains biochar activation and its effects on the characteristics of the final products to be used as sorbents or catalysts support, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8296, https://doi.org/10.5194/egusphere-egu2020-8296, 2020.

In boreal peatland forests, drainage and harvesting increase nitrogen (N) export to watercourses and the highest N concentration in runoff water occurs outside the growing season when traditional water protection methods based on biological activity are inefficient. In these conditions, water purification based on adsorption could offer a solution. Biochar can be an effective sorbent material for removal of nutrients from water due to its high specific surface area, porous structure and high cation and anion exchange capacity. We tested adsorption capacity for total N (TN) of spruce and birch biochar using water collected from ditch drains of boreal harvested peatland. The water was collected outside the growing season when TN concentration was 4.6 mg L^-1. During the growing season, TN concentration varies from 0.5 to 2 mg L^-1. To study the effect of TN concentration on adsorption capacity, we diluted water samples to concentrations 1, 2, 3 and 4 mg L^-1. We added 5 g of biochar to 1 L of water and shook the samples for 180 h. TN adsorption capacity increased monotonously from the smallest to the highest concentration. Adsorption capacity was 2.6 and 3.7 times greater in the highest concentration compared to the lowest concentration in spruce and birch, respectively. This indicates that concentration affects significantly the capacity of biochar to adsorb N from forest runoff water. Therefore, biochar can be an effective water protection tool in areas, which have high TN concentration, and it can be a complementary method supporting water purification outside the growing season.

How to cite: Palviainen, M., Kakaei Lafdani, E., Cvetkovic, J., Saarela, T., Pumpanen, J., and Laurén, A.: Concentration affects significantly the capacity of biochar to adsorb nitrogen from forest runoff water, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3429, https://doi.org/10.5194/egusphere-egu2020-3429, 2020.

Trace metals emissions show a sustaining decrease in western Europe since several decades. Sources like leaded fuels have been banned and the use of efficient flue gas cleaning systems have reduced industrial emissions significantly. But trace metal additions are cumulative, and the contamination is permanent. Immobilizing trace metals can be an efficient and cost effective way to prevent groundwater contamination and uptake in the food chain but cannot account for all exposure pathways (e.g. ingestion), while guideline values are only concerned about total concentrations. Soil washing techniques comprise an enormous potential for the efficient and sustainable extraction of trace metals from contaminated soils. The Garden Soil Project is a case study investigating the effect of soil amendments applied after a new ex-situ soil washing procedure (Ethylenediaminetetraacetic acid) from a Cd-, Pb-, Zn-contaminated Cambisol from Arnoldstein, located at a former lead mining and smelting region in Austria.

To investigate the success of the EDTA soil washing and amendment application, an experimental garden was set up at the University Research Center (UFT) in Tulln an der Donau. It encompasses twelve raised beds of 1 m³, filled with three soil variants in four replicates: The contaminated, unwashed soil (U) and two washed variants (W), one amended with 2 %wt biochar and 2 %wt compost (A). The amendments aim to restore soil conditions after the invasive procedure. The success of the trace metal extraction and restoration of the original soil properties is investigated by analyzing vegetable cultivars grown on the soil variants, the physicochemical and microbiological characteristics of the soil in the course of 2 years. First results show a significant reduction in trace metal uptake by different vegetables after washing and an increase in biomass for both washed soil variants W and A. The continuing analysis of trace metals in soil leachates and multiple extractable fractions in soil will allow a more detailed assessment. Furthermore, an ongoing investigation of the carbon and nitrogen cycle, using stable isotopes, will be applied as an indicator for soil functions.

How to cite: Friesl-Hanl, W., Noller, C. S., Hood-Nowotny, R., and Watzinger, A.: A case study investigating the effects of EDTA washing and amendments on trace metal-contaminated soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3488, https://doi.org/10.5194/egusphere-egu2020-3488, 2020.

In the present study, we investigated the effect of the adsorption of cationic and nonionic surfactants on the structure of bentonite. Although there is a large amount of data on the modification of bentonite with different surfactants, information regarding the effect of a nonionic surfactant on the properties of bentonite is limited. Nonionic surfactant-based organo-bentonites are less toxic and more environmental‐friendly, thus their application as sorbents should be evaluated. 

For modification of bentonite two surfactants were used: t-octylphenoxypolyethoxyethanol (Triton X-100; TX100) and hexadecyltrimethylammonium bromide (HDTMA). The samples of bentonite were stirred with 2000 g of HDTMA or TX100 solutions at concentrations of 48 mmol/100 g at 40 °C. After 24 h of stirring, the samples were centrifuged for 10 min at 14,000 rpm and dried at 40 °C for 24 h.

XRD results show that the main peak (001) from montmorillonite was observed to shift towards higher interlayer distances only in case of modification with HDTMA. This indicates that TX100 molecules are too big and cannot intercalate into interlayer space of montmorillonite; therefore, the modification of bentonite with TX100 was seen mostly on the surface. The FTIR spectrum of HDTMA-modified bentonite shows bands which correspond to the anti-symmetric and symmetric tensile vibrations of methylene groups (–CH₂) of the hydrocarbon tails of the surfactants and bandsis ascribed to the bending vibrations of C–H originated from surfactant molecules. The effectiveness of the modification of bentonite with TX100 is confirmed by the presence of the absorption bands, which represent methylene groups (–CH₂), CH stretching and bending vibrations, CO and OH bending vibrations and a band from C–C bonds of phenyl rings. DTA curves of HDTMA-bentonite indicate the occurrence of several endothermic and exothermic effects. Exothermic effects in the temperature range of 303–383 °C are attributed to the combustion and loss of the surfactant molecules from the surface and from the interlayer space. For bentonite modified with TX100 exothermic effects related to the decomposition or combustion of TX100 are strong and shift to high temperatures (approximately 250 °C and 400 °C). The interaction of surfactant molecules with the structure of the mineral minimizes the disintegration of the surfactant, which occurs at a temperature higher than what is required to disintegrate pure TX100. The morphology of the sample after the modification with HDTMA did not change significantly with respect to natural bentonite; thus, the typical tissue-like morphology of montmorillonite is evident. It is caused by the modification type—HDTMA is mostly intercalated into the interlayer space of smectite. Modification with TX100 takes place mostly on the surface of the sample; thus, the surface is coated with surfactant.

In conclusion, this work demonstrates the changes in bentonite due to adsorption of the cationic and nonionic surfactants. Intercalation of surfactants increases the structural and thermal stability of the system. The results achieved by this study can contribute to the further exploration of the utilization of nonionic surfactants in clay and clay mineral modification.

This research was funded by AGH-UST, grant number 16.16.140.315.

How to cite: Andrunik, M. and Bajda, T.: Effect of surfactants adsorption on the structure of bentonite-based sorbents, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7890, https://doi.org/10.5194/egusphere-egu2020-7890, 2020.

Hydrogels (HGs) are conventionally defined as a natural or synthetic polymeric 3D networks with high hygroscopicity and water-swelling properties. Over the decades, HGs have been widely utilized in various fields of cosmetics, food additives, tissue engineering, drug delivery, and pharmaceuticals. Only recently HGs have been studied also for agronomic purpose. Indeed, their unique physical properties, including their porosity and swellability, make them ideal platforms for water and nutrient delivering. The aim of this study was to investigate the potentialities of two HGs, one formed by polyacrylamide and one by cellulose added with clay and humic acids, for improving soil porosity of three soil types (sandy “SD”, silty “SL” and clay “CL”). Soil pore network was characterized with X-ray computed microtomography (µCT) at 50 µm resolution and subsequent image analysis measuring  total porosity (TP), pore size distribution (PSD), mean diameter (MD), connectivity density and degree of anisotropy. Soil samples were at first saturated and then dried trough freezing and drying cycles with acetone at -80°c.

Preliminary results showed that at water saturation HG increased TP of four- and two-fold, respectively for SL and CL soil, MD of 40 (SD), 519 (SL) and 164 µm (CL) while no effects were found on other pore architecture indices (e.g., connectivity or anisotropy). The PSD analysis highlighted that HG increased the macroporosity fraction (e.g., pore > 0.8 mm) only in SL (+36%) and CL (+11%) while the other pore classes were not affected. Present study demonstrated that in fine-textured soils at high water content, HG might be a valuable tool to increase not simply the TP but, in particular, the macroporosity fraction which may play a key role in soil functioning and ecosystem services. Future research will investigate the HG performances under dynamic soil moisture conditions on water holding capacity and hydraulic conductivity (Research supported by Fondazione CARIPARO, InnoGel, Progetti Eccellenza 2017).

How to cite: Piccoli, I., Sara, P., Camarotto, C., Squartini, A., Guerrini, G., and Morari, F.: Investigating hydrogel potentialities for improving soil pore network by using X-ray computed microtomography, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9985, https://doi.org/10.5194/egusphere-egu2020-9985, 2020.

Landfill leachate is a type of wastewater generated in a landfill and may lead to serious environmental pollution due to its complex composition. The main aim of the present research is to investigate the interaction of sanitary landfill leachate with sorbent materials, and the comparison among leachates of different origin. A better understanding of the process can lead to a cost-effective choice with the appropriate combination of the adsorption stage with other treatments. Various sorbent materials such as a commercial activated carbon (granular and powder), and two agro-industrial by-product biomaterials; grape seeds and rice husks (granular) were used. Two different samples of landfill leachates were examined. Initial samples were characterized by high COD (22 and 29 g/L), and high concentrations of nitrogen, in the form of NH₄⁺-N (2,500 and 1,100 mg/L). Since raw leachates used were characterized by high organic COD load, a dilution (1:5) of all samples was necessary. Duplicates of each sorbent (3 g) were mixed with duplicates of each leachate sample (30 mL). Experiments were carried out in glass vials sealed with Teflon caps. The kinetics of the leachates sorption on sorbent materials was investigated over a time of two months. Chemical Oxygen Demand (COD) was determined with the Standard Dichromate Reflux Method, while ammonium nitrogen determination was based on the colorimetric Koroleff method. COD reduction was more significant for the sample with the lowest initial COD value, for each sorbent material used. At the beginning (3 days) of the experiment, for the samples with the lowest initial COD value, a significant reduction of COD (~45%) by activated carbon (powder and granular) sorption was observed, while for the same sorbents but samples with the highest initial COD value, the reduction of COD reached up to ~15% and up to ~93% after 120 days. Grape seeds and rice husks showed a lower reduction of COD for both samples. COD reduction increased over time with different rates for various samples.  In addition to the reduction of the organic load, nitrogen, in the form of NH₄⁺-N, and color removal was also observed for all leachate samples. The different kinetic behavior for the two leachate samples suggests that the organic molecules present in each leachate demonstrate various sorptive behaviors with different affinity for each sorbent.

Acknowledgment

We acknowledge support of this work by the project “Research Infrastructure on Food Bioprocessing Development and Innovation Exploitation – Food Innovation RI” (MIS 5027222), which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).

How to cite: Karapanagioti, H. K., Athanasopoulou, K. P., Evangelidou, C., and Theodosiou, C.: Treatment of municipal landfill leachate by using different sorbent materials, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10278, https://doi.org/10.5194/egusphere-egu2020-10278, 2020.

Anthropological use of land and resources releases vast amounts of waste into surface waters and aquifers. Copper(II) is one of the most widely occurring heavy metal contaminants, introduced into the environment from industrial discharge, landfill leakage, agricultural and mining sources. Common remediation strategies for redox-sensitive Cu(II) are based on adsorption or phytoremediation methods. To experimentally test the efficiency of Cu(II) retention by inorganic redox reaction processes suitable for in situ surface- and groundwater remediation applications, we used siderite (FeCO₃), which is abundant in anoxic sediments and soils and as a carbonate highly soluble in acidic environments. Its dissolution increases alkalinity and releases highly reactive, redox sensitive Fe(II). This aqueous ferrous iron can act as 1) a precursor for Fe(III) (hydr)oxides in oxic conditions, which are effective sorbents of heavy metals, and 2) a reducing agent under reducing conditions, where it can form a strong redox couple with Cu(II). We investigated the long term (1008 h) removal of aqueous Cu(II) through siderite dissolution batch experiments under oxic and anoxic conditions and monitored changes in the aqueous concentrations of Cu and Fe, pH and the reacted solids morphology over time. Cu adsorption and speciation on the reaction products was determined by X-ray absorption and photoelectron spectroscopies.

Under oxic conditions, increasing alkalinity led to a rapid increase in solution pH and the precipitation of nanoparticulate goethite and hematite from the released ferrous iron. After 1008 h of reaction, 80 % of the dissolved Cu(II) were removed from solution by sorption, whereby up to >30 % of this sorbed Cu(II) was reduced to Cu(I). Under anoxic conditions, the solution pH increased abruptly and copper uptake occurred more than twice as fast as under oxic conditions. Notably, the released Fe(II) was oxidized by Cu(II) leading to the precipitation of lepidocrocite, while all copper was removed from solution with >70 % of Cu(II) being reduced to Cu(0).

Our results suggest that 1) redox reactions between aqueous Cu(II) and Fe(II) promote coupled dissolution-precipitation and adsorption mechanisms responsible for Cu(II) removal, and that 2) siderite is a low-cost and effective material that is potentially useful for in situ remediation in either oxygenated or reduced environments.

How to cite: Füllenbach, L. C., Perez, J. P. H., Freeman, H. M., Thomas, A. N., Benning, L. G., and Oelkers, E. H.: Copper(II) removal by natural siderite (FeCO3) from surface and groundwaters, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11678, https://doi.org/10.5194/egusphere-egu2020-11678, 2020.

Soil application of raw winery wastes is a procedure of doubtful appropriateness, mainly because of waste properties, i.e. very acidic pH; high electrical conductivity; and high content of polyphenols. The disposal of winery waste on soils may cause various environmental and health hazards as for example soil overloading with polyphenols and salts, phytotoxicity to plants, odor nuisance etc. Pathogens, which may still be present in the decomposed material could spread plants and soil diseases, while waste piles attract insects, pests, domestic rodents and wildlife which may threaten public and animal health. Despite these facts, many wine producers discharge winery waste to the nearby agricultural or forest ecosystems, without treatment although this type of agricultural waste could be a significant source of organic matter and nutrients.

In general, degradation of winery waste is a slow procedure which becomes even slower under the xerothermic climatic conditions in Greece, which may slow down the microbially mediated decomposition of organic matter and nutrients cycling; degradation of winery waste piles takes more than 5 years to be completed naturally. However, the final products are of doubtful appropriateness for fertilization use, mainly because of low quality organic matter and low nutrients content (lost mainly due to the exposure of piles to uncontrolled environmental conditions for years).

This study aims to highlight the advantages of composting winery wastes by using also other agricultural wastes and additives as feedstock to produce a safe and environment friendly compost, appropriate for application to agricultural ecosystems. For this a 41 hectares vineyard in North Greece of about 400 tn grapes yield annually and generation of approximately 100 tn of waste was selected. Winery waste was collected after harvesting and wine-making period of 2018 and composted with cow manure, wheat straw and clinoptilolite up to 5%.

Composting phase lasted 5 months, and during this period the pile was monitored as regard temperature, moisture and oxygen content. After composting completion, the final product was fully characterized in terms of its physical and chemical properties, considering national legislation organic materials reuse on soils. The outcomes of this study show a great potential for managing such waste types by composting using clinoptilolite in the feedstock materials since the final product has suitable physical and chemical properties for many crops, i.e. slight alkaline pH, low electrical conductivity, low polyphenol content and high content of available nutrient, therefore can be used as soil amendment or organic fertilizer.

How to cite: Kolovos, C., Doula, M., Kavasilis, S., Zagklis, G., Tsitselis, G., and Kostopoulos, P.: Composting winery wastes with clinoptilolite. Suitability for land application., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13496, https://doi.org/10.5194/egusphere-egu2020-13496, 2020.

The use of biosorbents (adsorbents of natural origin, such as, plant derived material) has been regarded as an alternative to traditional wastewater treatment methods (such as chemical precipitation or ion exchange), as it is environmentally friendly and cost-effective process. Literally hundreds of different biosorbents have been tested in laboratory scale sorption experiments, however, the traditional research of biosorbents (i.e., the use of biosorbents in the treatment of polluted waters) seems to be a dead-end direction, with technological problems that are difficult to overcome, and process has found no application on industrial scale until now. For example, biosorbents are short-lived, as the biomass decomposes in the solution, and as a result, it is fragile to technological operations such as mixing or pumping. There are also problems with regeneration and reuse of biosorbents. It explains why this process has not been implemented in industrial scale so far. In addition, the focus in biosorption studies has always been more on the “removal” (i.e., concentration of pollutants into a biosorbent, however this material will become a waste after the biosorption), but not so much on the “recovery”. Therefore, there is an opportunity, as well as challenge to apply biosorption principles in unconventional manner. A new concept will be proposed, with shift away from adsorption of toxic elements to adsorption of essential elements. 

How to cite: Robalds, A.: Saturated biosorbents: shift from waste to new class of materials , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13776, https://doi.org/10.5194/egusphere-egu2020-13776, 2020.

The occurrence of dyes in wastewater is a threat for environment and living organisms. Therefore many studies have focused on investigation of diverse sorption materials to develop effective adsorption methods of removing these organic compounds (Yagub et al., 2014). Among the wide range of materials, the low-cost sorbents such as clay minerals, fly ash or lignite have received unflagging interest. However, the novel approach is to mix low-cost sorbents, clay minerals with fly ash or lignite, which could promote efficiency of removing chemically varied dyes and impact the modification of sorbent mixtures properties. Thus, the aim of this study is to investigate and compare features of hybrid sorbents: halloysite-fly ash, palygorskite-lignite before and after sorption reactions of selected dyes and evaluate influence of modified properties on their sorption mechanism. The obtained reactions’ products, as well as hybrid and selected raw sorbents after reactions, were studied by Fourier-transform infrared spectroscopy (FTIR), thermal analysis (DTA/TG) coupled with the measurement of evolved gases composition by mass spectrometer (QMS). The morphology of raw sorbents was analyzed by scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) for elemental microanalysis. The results show that sorbents features, especially the presence of organic functional groups, negative surface charges, have distinct impact on their sorption behaviour. Each componnent of hybrid sorbents affects the efficiency of dyes sorption. The obtained results revealed that mixing of various low-cost sorption materials may present unexpected properties.

Acknowledgments.

The studies results have been presented with the partial financial support from the EU project of POWR.03.02.00-00-I038/16-00.

Literature:

Yagub M. T., Kanti Sen T., Afroze S., Ang H.M. (2014) Dye and its removal from aqueous solution by adsorption: A review, Advances in Colloid and Interface Science, 209, p. 172-184.

How to cite: Solińska, A. and Bajda, T.: The low-cost hybrid sorbents for immoblization of dyes: sorbents features characterization, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13944, https://doi.org/10.5194/egusphere-egu2020-13944, 2020.

Lead contaminated soils occurred at lead-acid battery manufacturing and recycling sites are of great concern. Bench-scale batch experiments of stabilization treatment were conducted using twelve materials and three phosphorus-based materials, KH₂PO₄(KP), KH₂PO₄:oyster shell power = 1:1 (by mass ratio; KSP), and KH2PO4:sintered magnesia = 1:1(by mass ratio; KPM), were screened out for lead contaminated soil in an abandoned lead-acid battery factory site. The three materials had higher remediation efficiencies that led to a 92% reduction in leachable Pb and 12% reduction in bioaccessible Pb with the addition of 5% material, while the acid soluble fraction of lead decreased by 41–46%. The lead activity in the soil solution sharply decreased treated by three materials. Pb₅(PO₄)₃Cl was the primary mineral controlling lead solubility in soil treated by KP and KSP and lead activity was related to Pb₅(PO₄)₃OH and Pb₅(PO₄)₃Cl in soil amended with KPM.

How to cite: Zhang, Z., Guo, G., and Li, F.: Efficiency and mechanism of lead stabilization in soil of lead-acid battery contaminated site with phosphorus-based materials, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21195, https://doi.org/10.5194/egusphere-egu2020-21195, 2020.

In this study, we report the effectiveness of natural and NaOH treated Moringa oleifera seeds for single and simultaneous Pb²⁺ and Cd²⁺ from aqueous solutions. The biosorbent was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. The pH of point zero charge (pH_pzc) was determined. Effects of contact time (15-1440 min), pH of solutions (2-10), mass of biosorbent (0.1-0.5 g) and initial metal ion concentration (10-1000 mg/L) were investigated using batch tests. The results show the pretreatment of biosorbent by NaOH improve significantly uptake capacity (mg/g) of the metal ions (q (Pb²⁺) = 38.45 and q (Cd²⁺) = 17.32 ˃ q (Pb²⁺) = 31.45 and q (Cd²⁺)= 14.67). Kinetic studies shown that the more than 90 % uptake of ion metals occurring within 120-180 min and the experimental data were better describe by a pseudo-second-order model. The sorption data for non-treated and NaOH treated Moringa oleifera seeds were evaluated by the Freundlich isotherm models to describe the adsorption equilibrium.

How to cite: Abatal, M., Durán Avendaño, Y. S., Olguin, M. T., and Vargas, J.: Moringa oleifera seeds for single and simultaneous removal of Pb2+ and Cd2+ from aqueous solutions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22214, https://doi.org/10.5194/egusphere-egu2020-22214, 2020.

Advanced oxidation processes (AOPs) based on persulfates have become very popular for in-situ water/wastewater treatment since persulfates are more stable and less costly than other oxidants such as hydrogen peroxide. The conversion of persulfates to sulfate radicals requires an activation agent, including transition metals, high temperature, ultraviolet irradiation, ultrasound irradiation, and microwaves. Recently, there have been several reports concerning the use of carbonaceous materials such as graphene, graphene oxide, carbon nanotubes, and activated carbons as persulfate activators. Biochars, the solid residue produced from biomass thermal decomposition with no or little oxygen at moderate temperatures, are low-cost materials with high surface area and desirable physicochemical properties in terms of pore size distribution, the number of functional groups, and minerals that can be employed as catalytic supports.

The aim of this work is to test whether biochar produced from malt spent rootlets (MSR) and olive kernels are suitable activators of persulfates for the degradation of sulfamethoxazole (SMX) under various operating conditions and aqueous matrices.  Olive kernels and MSR were pyrolyzed at 850 and 900^oC, respectively.  The actual matrix effect on degradation was minor and so was the effect of radical scavengers. Persulfate activation seems to occur on the biochar surface through interactions with the surface functional groups, generating radicals that are not released in the solution.

How to cite: Manariotis, I. D., Kemmou, L., Magioglou, E., Frontistis, Z., Vakros, J., and Mantzavinos, D.: Activation of persulfate by different biochars for the degradation of sulfamethoxazole , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13786, https://doi.org/10.5194/egusphere-egu2020-13786, 2020.