Utilization of steelmaking waste as a sustainable low-cost adsorbent for cationic and anionic dyes removal

An effective magnetic polymeric composite was produced from steelmaking waste in this work. For the elimination of methyl orange MO and methylene blue MB from synthetic solutions, steel slag was treated with an acrylamide acrylic acid (SSAA) copolymer. TGA thermogravimetric analysis, SEM scanning electron microscope, XRD X-ray diffraction, BET Brunauer-Emmett-Teller surface area, and FTIR Fourier transform infrared were used to analyze the SSAA composite. The SSAA adsorption behavior for MO and MB was studied, and the impact of various factors was analyzed using one factor at a time (OFAT) and the RSM-BBD response surface method-Box Behnken Design. The second-order kinetic model accurately described the kinetic data of MO and MB, and the primary rate-limiting phase is film diffusion. The Dubinin-Raudshkevish (D-R) and Freundlich isotherms accurately characterized the MB and MO experimental outcomes, respectively. MO and MB had maximal absorption efficiencies of 97% and 94%, respectively, and capacities of 47 and 463 mg/g. The thermodynamic studies revealed that MO and MB adsorption on the SSAA was favorable and spontaneous. Physical adsorption was discovered to be the dominant mechanism for MB, whereas chemisorption was identified for MO. The regeneration investigation verified these mechanisms, in which SSAA was regenerated for MB and a negligible decline in adsorption capacity was seen after five cycles. However, for MO ions, a minor renewal of the SSAA was achieved, confirming the chemisorption mechanism. According to the thermodynamic study, the SSAA composite might be employed for the removal of cationic and anionic dyes from wastewater spontaneously and feasibly.