Sustainable Arsenic Removal from Contaminated Water Using Al–Fe Modified Rice Husk Biochar

Abstract

Arsenic pollution of groundwater is a major water quality concern, especially in developing nations where groundwater is widely used for drinking purpose. Continuous exposure to arsenic from contaminated water can create serious health problems, including carcinogenic and cardiovascular consequences, emphasizing the critical need for effective, low-cost and long-term water treatment methods. This study looks into the efficacy of rice husk-derived biochar enhanced with iron and aluminium oxides as an adsorbent for removing arsenic from contaminated water sources. Rice husk biochar was generated by controlled pyrolysis and then treated with iron and aluminium oxides to increase its surface characteristics and adsorption capability. The physicochemical properties of the modified biochar were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction. The characterisation results demonstrated increased surface roughness, porous morphology, and the presence of Fe-O, Al-O and hydroxyl functional groups, which are known to play important roles in arsenic adsorption via surface complexation and electrostatic interactions. Batch adsorption tests were conducted under controlled conditions to determine the effect of contact time on arsenic removal efficiency. The findings revealed a rapid initial uptake of arsenic, followed by a slow restoration of equilibrium. After 24 hours of contact, the arsenic removal effectiveness was around 99%, indicating a robust interaction between arsenic species and the modified biochar surface. The enhanced adsorption effectiveness is due to the combined action of iron and aluminium oxides, which provide a large number of active binding sites for arsenic immobilization. The results show that rice husk biochar treated with Al–Fe is a sustainable, eco-friendly, and efficient adsorbent for removing arsenic from water. The proposed material exhibits considerable promise for groundwater purification and decentralized water and wastewater treatment systems, especially in arsenic-affected and resource-limited locations, due to its high treatment efficiency, straightforward preparation procedure and adaptability.