High concentration arsenic removal from aqueous solution using nano-iron ion enrich material (NIIEM) super adsorbent

Abstract

Nano iron ion enrich materials (NIIEM) is a new commercial adsorbent employed to remove inorganic arsenic (As) toxicant from aqueous solutions. In this study, BET, SEM, EDX, XRF, XRD and TG-DTG were used to characterize this commercial adsorbent before and after contact with As(III)/As(V). NIIEM is composed mostly of core shell Fe0 structure with an outer oxide and hydroxide shell. The SEM analysis of NIIEM after arsenic adsorption was characterized by the formation of agglomerates into larger particles (clusters). The XRD results revealed that NIIEM (Fe0) were transformed to Ferrihydrite (Fe5O7(OH)·4H2O) corrosion products at high concentration of As(III)/As(V) under acidic conditions. The batch experiments conducted to describe the adsorption affinity of NIIEM depicted that its adsorption kinetics adopted a pseudo-second-order model with high affinity for both As(III) and As(V) at initial pH 2.5. Maximum adsorption capacity determined at initial pH 2.5 from the Langmuir-Freundlich isotherm model was found to be 704.7 and 122.7 mg/g for As(III) and As(V), respectively. These results indicate that NIIEM has high adsorbent efficiency and it is very suitable for in-situ and ex-situ remediation of highly concentrated As(III) and As(V) toxicants in aqueous solutions.