Enhanced removal of radioactive iodine anions from wastewater using modified bentonite: Experimental and theoretical study. (April 2022)

• Record Type: Journal Article
• Authors: Yang, Junqiang; Tai, Wenya; Wu, Fei; Shi, Keliang; Jia, Tianyi; Su, Yin; Liu, Tonghuan; Mocilac, Pavle; Hou, Xiaolin; Chen, Ximeng
• Is Part Of: Chemosphere. Volume 292(2022)
• Publication Date: 2022-04
• Subjects: Radioactive iodine -- Modified bentonite -- Adsorption -- Density functional theory -- Wastewater; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.133401
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Efficient and cost-effective removal of radioactive iodine anions from contaminated water has become a crucial task and a great challenge for waste treatment and environmental remediation. Herein, we present hexadecylpyridinium chloride monohydrate modified bentonite (HDPy-bent) for the efficient and selective removal of iodine anions (I − and IO3 − ) from contaminated water. Batch experiments showed that HDPy-bent could remove more than 95% of I − and IO3 − within 10 min, and had maximum I − and IO3 − adsorption capacities of 80.0 and 50.2 mg/g, respectively. Competitive experiments indicated that HDPy-bent exhibited excellent I − and IO3 − selectivity in the excessive presence of common concomitant anions including PO4 3−, SO4 2−, HCO3 −, NO3 −, Cl − (maximum mole ratio of anions vs iodine anions was ∼50, 000). An anion exchange mechanism was proposed for the selective adsorption of iodine anions. Optimal adsorption structure of HDPy + /I − (IO3 − ) at atomic level and driving forces of the I − (IO3 − ) adsorption were calculated by density functional theory (DFT) simulations. Moreover, the good durability and reusability of the HDPy-bent has been demonstrated with 5 adsorption-desorption cycles. Dynamic column experiment also demonstrated that HDPy-bent exhibited excellent removal and fractional recovery capabilities towards I − and IO3 − from simulated groundwater and environmental water samples. In conclusion, this work presents a promising adsorbent material for the decontamination of radioactive iodine anions from wastewater on a large scale. Graphical abstract: Image 1 Highlights: HDPy-bent showed excellent adsorption abilities for iodide and iodate. Anions exchange mechanism was confirmed by batch experiments and DFT simulations. The pyridine N was the intrinsic active site of the modified bentonite. HDPy-bent was efficient for removing radioiodine anions from wastewater.