Enhanced removal of I− on hierarchically structured layered double hydroxides by in suit growth of Cu/Cu2O

• Published in: Journal of environmental sciences (China) Vol. 88; pp. 338 - 348
• Main Authors: Chen, Jiuyu, Wang, Junyi, Gao, Qianhong, Zhang, Xiaomei, Liu, Ying, Wang, Peng, Jiao, Yan, Zhang, Zongxiang, Yang, Yi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2020
• Subjects: Cu/Cu2O; Hierarchical structure; In suit growth; Iodide adsorption; Layered double hydroxide; Cu/Cu2O; In suit growth; Layered double hydroxide; Iodide adsorption; Hierarchical structure
• ISSN: 1001-0742; 1878-7320
• DOI: 10.1016/j.jes.2019.09.024

To further improve the removal ability of layered double hydroxide (LDH) for iodide (I−) anions from wastewater, we prepared hierarchically porous Cu5Mg10Al5-LDH and used as a matrix for in suit growth of Cu/Cu2O on its surface, forming Cu/Cu2O-LDH, which was characterized and applied as an adsorbent. Results displayed high I− saturation uptake capability (137.8 mg/g) of Cu/Cu2O-LDH compared with Cu5Mg10Al5-LDH (26.4 mg/g) even thermal activated LDH (76.1 mg/g). Thermodynamic analysis showed that the reaction between I− anions and Cu/Cu2O-LDH is a spontaneous and exothermic. Uptake kinetics analysis exhibited that adsorption equilibrium can be reached after 265 min. Additionally, the adsorbent showed satisfactory selectivity in the presence of competitive anions (e.g., SO42−), and could achieve good adsorption performance in a wide pH range of 3–8. A cooperative adsorption mechanism was proposed on the basis of the following two aspects: (1) ion exchange between iodide and interlayer anions; (2) the adsorption performance of Cu, Cu(II) and Cu2O for I−. Meanwhile, the difference between the adsorption mechanism of Cu/Cu2O-LDH, Cu5Mg10Al5-LDH and Cu5Mg10Al5-CLDH adsorbents was also elaborated and verified. [Display omitted]