Application of a superior magnetic hydroxy iron material for arsenic removal from soil

Magnetic removal technology enable rapid removing arsenic from soil. However, the high cost of magnetic arsenic removal materials folimited its application. A magnetic arsenic removal material which is much less costly was introduced in this study. CTAB@β-FeOOH@Fe₃O₄ (C-M-MFe), a composite modified montmorillonite, was synthesized and investigated for its adsorption performance, mechanism, and remediation efficacy in arsenic-contaminated soil. The results indicate that the maximum theoretical adsorption capacities of the material for As(Ⅴ) and As(Ⅲ) are 74.90 mg g^-1 and 67.81 mg g^-1, respectively. The adsorption mechanism involves electrostatic attraction, inner-sphere complexation, and precipitation. Moreover, our findings suggest that the potential synergistic oxidation of As(Ⅲ) facilitated by Fe(Ⅲ) in β-FeOOH and structural Fe(Ⅱ) in magnetite, may contribute to adsorption efficiency. Under the conditions of 1:1 (g:g) of soil slurry solid-liquid ratio, 1% of adsorbent dosage, and more than 12 h of treatment duration, C-M-MFe could strongly reduce 92.14% of available arsenic and also 44.09% of specifically adsorbed arsenic in the soil. Finally, the total arsenic removal rate reached 10.83%, with an adsorbent recovery rate of 92.44%. Compared with other magnetic arsenic removal materials, the C-M-MFe developed in this study is an efficient adsorbent of arsenic with low cost. Plus that we found that As(Ⅲ) might be oxidized by β-FeOOH in adsorption process, which contribute to solve the tough problem of As(Ⅲ) removal. The results of this paper offered a promising potential method for arsenic removal from contaminated soils. ENVIRONMENTAL IMPLICATIONS: This research developed a cost-effective adsorbent for arsenic removal, which possesses both magnetic and catalytic oxidation properties. Our study elucidated the primary adsorption mechanism and evaluated its application effectiveness in contaminated soil. By leveraging the adsorption and catalytic oxidation capabilities of β-FeOOH, we achieved an enhancement in the removal of As(III). This approach offers a promising strategy to improve As(III) removal efficiency while minimizing the required adsorbent dosage, thus holding potential for practical applications in remediating arsenic-contaminated soils.