Manganese metal ion removal from aqueous solution using industrial wastes derived geopolymer

Abstract

Heavy metal pollutants, highly toxic and invisible, have garnered attention due to bioaccumulation. Increased manganese production from steel industries is expected to lead to harmful concentrations in water, adversely affecting the environment and public health. The sustainable approach of utilizing industrial by-products to synthesize geopolymers for the immobilization of heavy metal ions has gained research interest. The current study aims to verify the feasibility of Paper sludge ash (PSA) in conventional geopolymer (CGP) to immobilize manganese (Mn) heavy metal ions from aqueous solutions. CGP was prepared using Fly ash (FA) as resource material, which was replaced by PSA at a level of 30 %, by weight. The precursors were treated with alkali solutions, namely sodium hydroxide and sodium silicate, incorporating ambient curing. The characterization studies of precursors and CGP were investigated using XRD, XRF, SEM, EDS, FTIR, and Brunauer-Emmett-Teller surface area (BET) analysis techniques to outline the crystal structure, morphology, and pore parameters. Additionally, the experimental investigation comprehensively examined the impact of various pH levels, dosages, contact times, and initial concentrations on the removal efficiency of Mn heavy metal ions. The difference in concentration of Mn heavy metal ions quantified by atomic absorption spectrometry. The Langmuir models effectively explained the removal of Mn ions by CGP due to high fitting coefficients. The highest value of uptake capacity was found to be 28 mg/g at 30 °C with pH value of 4. Therefore, blending industrial wastes improves the potential of decontamination agents in removing heavy metals from wastewater, promoting environmental sustainability.