* Corresponding authors. 1944-3994/1944-3986 © 2020 Desalination Publications. All rights reserved. Desalination and Water Treatment www.deswater.com doi: 10.5004/dwt.2020.26326 206 (2020) 273–285 December Selective chelation adsorption of copper ion on KH550 modifed acid-activated atapulgite Weiying Wang a , Hongzhe Chen b , Lin Wang c , Shaogui Yang d, *, Yong Wang a, * a State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, School of Environment, Northeast Normal University, Changchun, Jilin Province, China, Tel. +86-18628795197; email: wangy833@nenu.edu.cn (Y. Wang), Tel. +86-13578933513; email: wangwy808@nenu.edu.cn (W.Y. Wang) b Ministry of Natural Resources, Third Institute of Oceanography, Xiamen, Fujian Province, China, Tel. +86-0592-2195219; email: chenhongzhe@tio.org.cn (H.Z. Chen) c China Environment Publishing Group, Beijing, China, Tel. +86-010-67110245; email: wangalcn@126.com (L. Wang) d School of Environment, Nanjing Normal University, Nanjing, Jiangsu Province, China, Tel. +86-25-85891849; Fax: +86-25-85891849; email: yangdlut@126.com (S.G. Yang) Received 2 August 2019; Accepted 16 July 2020 abstract In this study, KH550 modified acid-activated attapulgites (KH550-HATP) were prepared and assessed for their capacity to remove Cu(II) ion from aqueous solution. The obtained adsorption behavior using different KH550-content KH550-HATP revealed that Cu(II) adsorption onto KH550-HATP followed pseudo-first-order kinetics and was mainly controlled by film diffusion mechanism. And there is a considerable contribution of the intraparticle diffusion effects for low KH550-content KH550-HATP. In addition, adsorption isotherms indicate that the adsorption pattern on KH550- HATP fit well with the Langmuir isotherm, and the maximum monolayer adsorption capacity for Cu(II) at temperatures of 283, 293, 303, and 313 K were 3.33, 5.92, 9.75, 13.85 mg g –1 , respec- tively, where the characteristic parameters for each adsorption isotherm were also determined. The adsorption process confirmed endothermic reactions in the range from 283 to 313 K. X-ray diffraction, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy patterns of KH550-HATP before and after Cu(II) adsorption manifest both interlayer ion exchange and sur- face complication play important roles. Results of competitive adsorption of several different metal ions show that KH550-HATP has adsorption capacity on Cu 2+ , Cd 2+ and Ca 2+ , among which Cu 2+ is chelated by KH550 selectively. These findings indicate that KH550-HATP could be an effective and environmentally friendly selective adsorbent for removing Cu(II) from wastewater. Keywords: KH550 modified acid-activated attapulgites; Cu(II); Adsorption behavior; Adsorption mechanism 1. Introduction Heavy metal contamination is a major environmental problem. Once leaching from landfill runoff [1], discharg- ing from industrial/military wastewater [2] or erosion by acid rain [3], heavy metals may pose a threat to human health. In addition, heavy metals leaching into adjacent soil could reduce the complexity of soil bacteria [4]. In which, copper is an essential nutrient for humans, animals and