Rice husk ash adsorbent modified by iron oxide with excellent adsorption capacity for arsenic removal from water

A low-cost and efficient adsorbent for arsenic removal from drinking water is fabricated using rice husk ash (RHA) and iron oxide nanoparticles. The carbonization of rice husk biomass obtains the RHA at 600 degrees C under deoxygenated conditions. In contrast, the iron oxide nanoparticles are prepared by the wet chemical method. The physicochemical properties of iron oxide modified RHA adsorbent is characterized by using FTIR, SEM, EDX, and N-2 adsorption-desorption. The FTIR results reveal the presence of magnetite, hematite, and silica oxide in the adsorbent. SEM images show that the adsorbent has a rough, porous, and tubular structure with embedded iron oxide nanoparticles in RHA. Element analysis and BET surface area further confirm the iron oxide modification of the RHA adsorbent. RHA and iron oxide modified RHA adsorbents are employed to remove arsenic from drinking water through the adsorption process. The fabricated adsorbent was converted into a purification cartridge with a 100 mL/min flow rate and tried a groundwater sample with arsenic contamination of 40 ppm. A - 98% of the removal of arsenic metal is observed. In addition, various adsorption parameters such as pH, time, adsorbent dose, and metal concentration are optimized. Under optimized parameters, the adsorption capacity of iron oxide modified rice husk was 25.06 mg/g. The adsorption kinetics data are plotted using the Langmuir and Freundlich isotherms, and pseudo-first-order kinetics is observed. The stability of the adsorbent is examined by reusing it, and no significant difference is kept in its adsorption efficiency.