Synthesis and characterization of metal oxide based ion exchanger from chicken egg shell biomass for the removal of arsenic from water

Abstract

A new metal oxided-based high capacity biosorbent for As(III) was designed and synthesized from egg shell biomass and characterized using FTIR, FE-SEM, EDX, XRD, chemical analysis. For this, raw egg shell (RES) powder was first dissolved with HCl and mixed with ZrOCl2∗8H2O solution then precipitated to obtain hydrated double oxide precipitate (HDOP), which was employed for As(III) removal. As(III) biosorption onto HDOP is fast, depends on pH and As(III) concentration. Pseudo second order kinetics and Langmuir isotherm models successfully described the As(III) biosorption mechanism. HDOP provided exchangeable hydroxide/or chloride ligands for improved biosorption of As(III). Maximum biosorption capacity of HDOP for As(III) from Langmuir isotherm modelling was found to be 40 mg g−1 at optimum pH 10. Chloride and nitrate cause negligible interference whereas sulphate and phosphate significantly reduced As(III) biosorption capacity of HDOP. HDOP completely removed arsenic from contaminated ground water and the remaining concentration was reached below the safe drinking water standard (10 μg L−1) set by WHO. Moreover, HDOP exhibited effective regeneration and high stability with As(III) removal up to 8 cycles. Thus, HDOP synthesized from egg shell biomass can be used as a low cost, environmentally benign and high capacity biosorbent for the treatment of arsenic polluted water.