REMOVAL OF ARSENIC FROM CONTAMINATED WATER USING CHITOSAN BIOPOLYMER AS AN ADSORBENT DERIVED FROM SHRIMP OR CRAB SHELLS

Natural arsenic (As) in groundwater used for drinking, poses a severe environmental health risk for human in several parts of the world. It is essential to find out a safe, sustainable and eco-friendly treatment system for As removal prior to drinking water supply. A number of treatment processes exists, where many of them are not suitable due to their high costs and sustainability. Thus there is an urgent need for an inexpensive, sustainable and environment-friendly treatment system to remediate arsenic enriched water. This study was conducted to evaluate the viability of chitosan biopolymer as an adsorbent for As(V) from contaminated water. Bench-scale batch experiments were conducted using chitosan biopolymer with deacetylation degree (DD) of 85% to determine the As(V) removal efficiency, by considering five important operating parameters, namely pH, contact time, temperature, chitosan dosages and contaminant concentration. Characteristics of chitosan biopolymer were also studied by XRD, FTIR, TGA and SEM investigations. The kinetic data, obtained from performed analysis were tested for Pseudo-first and second order equations. Freundlich and Langmuir model were also studied at optimum conditions, observed from investigated operating parameters. Preliminary results show that the As(V) removal efficiency was 99% at pH 6. . The experimental results indicated that As(V) adsorption from contaminated water fitted with Pseudo-second order equation (R² = 0.9959) than Pseudo-first order (R² = 0.6735). In addition to this, the adsorption process was properly described by Freundlich (R² = 0.9933) kinetic model compared to Langmuir model (R² = 0.9741), which was an important indicator of homogeneous monolayer As(V) adsorption. The characterization of materials assured the presences of effective amino (N-H), hydroxyl (O-H) and carboxyl (C=O) groups of chitosan polysaccharide. These results directed that the chitosan biopolymer with deacetylation degree of 85% can be used as an inexpensive, sustainable and environment-friendly treatment option for arsenic contaminated drinking water. This study was one of the important components of FP7-SME project ChitoClean (SME - 2012-1-315087).