Dual-nutrient removal from eutrophic freshwater using ZeoPhos: Synthesis, characterization, and adsorption mechanisms of a multi-ion modified zeolite.

In recent decades, eutrophication, caused by the enrichment of nutrients in the water bodies
(mostly due to N and P), has emerged as a global environmental challenge with far-reaching
consequences for aquatic ecosystems health. ZeoPhos, an innovative eco-friendly clay-based
material, promises to simultaneously adsorb ammonium and orthophosphate ions, causing
eutrophication, from natural freshwaters. ZeoPhos consists of natural zeolite with a synergistic
combination of iron, calcium, and humic ions to enhance nutrient-binding affinity. Material
characterisation analysis (such as SEM/EDS and TEM) confirms that ZeoPhos successfully
altered the surface morphology and elemental composition, creating a more reactive surface for
adsorption. Batch adsorption kinetic experiments demonstrated high efficiency at achieving
removal rates of 78% and 70% for ammonium and orthophosphate ions, respectively. Pseudo-
second-order model of the kinetic studies suggests that the removal process is governed by
chemisorption, while the Langmuir model of isotherm studies indicate monolayer adsorption
onto a finite number of sites. The maximum adsorption capacities were 28.61mg/g and
27.13mg/g for ammonium and orthophosphate ions, respectively. ZeoPhos is an innovative,
economic and eco-friendly adsorbent material of high-capacity, capable of dual-nutrient
adsorption and ultimately promising to mitigate eutrophication in freshwater bodies.