Treatment of arsenic-contaminated groundwater with a novel iron oxide/carbon composite as the adsorbent

In this study, arsenic-contaminated groundwater is treated using a novel iron oxide/carbon composite. Raw chelating carbon materials with amidoxime functional groups were mixed with ferric chloride solution and then soaked to pH 3 solution to produce the composite. The specific surface area and adsorption volume of the iron oxide/carbon absorbent are 89.0 m²/g and 0.220 cc/g, respectively. Arsenic (1 mg/L) removal by different doses of the adsorbent (5 to 80 g/L) ranges from 49% to 79% in bath experiments. Arsenic removal increases with increasing dosage of the adsorbent. The adsorption kinetics and isotherm of arsenic removal reveal better fit for pseudo-second-order kinetic model and Langmuir isotherm, which indicates that the main mechanisms of arsenic adsorbed by the adsorbent are chemisorption and monolayer adsorption. Arsenic removal by the adsorbent within 15 to 35℃ has an insignificant difference, which indicates that the material is suitable to be applied under ambient temperature. The results of tank test show that the removal of arsenic (0.2 mg/L) by the adsorbent in the samples collected from in situ groundwater reaches 85%, demonstrating a good performance of the adsorbent for the treatment of arsenic-contaminated groundwater. The adsorbent used in this study can be applied to remediate arsenic-contaminated groundwater in the future.