Abstract:
This research aimed to study the efficiency of adsorbents for arsenic removal from groundwater. Three groups of adsorbents were studied: metal-organic frameworks, commercial adsorbents, and agricultural materials. Granular activated carbon (GAC) was modified by coating zeolitic imidazolate framework and doping ferric nitrate onto the GAC surface. Cassava biochar was also selected to modify the surface by coating ferric nitrate. The preliminary arsenic adsorption efficiency was first investigated to evaluate the suitable adsorbent employed in the column system. The preliminary results revealed that Fe-modified GAC (GAC-120-250Fe) exhibited a suitable performance, durable particle structure, and lower leaching of ferric ion and dissolved organic matter. The arsenic adsorption kinetic and isotherm of the GAC-120-250Fe corresponded to the pseudo-second-order kinetics and the Freundlich isotherm, respectively. In addition, the column adsorption study also indicated that increasing the adsorbent height can increase the breakthrough time by following the Bohart-Adams equation. The obtained breakthrough curves can be fitted well with Thomas's model. The most effective usage rate and empty bed contact time (EBCT) obtained from the column test were 286.2 ml/g and 15.7 min, respectively, at facial velocity 0.51 cm/min.