Adsorption of hexavalent chromium onto kaolin clay based adsorbent
来源期刊:中南大学学报(英文版)2014年第10期
论文作者:DENG Lin(邓林) SHI Zhou(施周) LUO Lu(罗璐) CHEN Shi-yang(陈世洋) YANG Ling-fang(杨灵芳) YANG Xiu-zhen(杨秀贞) LIU Li-shan(刘立山)
文章页码:3918 - 3926
Key words:kaolin clay; adsorption; Cr(VI); kinetics; isotherm; thermodynamics; desorption
Abstract: A low-cost adsorbent modified kaolin clay (MKC) was synthesized and utilized for Cr(VI) removal from aqueous solution. Adsorption experiments were carried out as a function of adsorbent dosage, solution pH, Cr(VI) mass concentration, contact time, electrolyte, and temperature. It is found that the adsorption efficiency is high within a wide pH range of 2.5-11.5, and equilibrium is achieved within 180 min. Increases in temperature and electrolyte concentration decrease the adsorption. The adsorption follows the pseudo-second-order kinetic model. The Langmuir isotherm shows better fit than Freundlich isotherm. The maximum uptake capacities calculated from the Langmuir model are 15.82, 15.55 and 15.22 mg/g at 298, 308 and 318 K, respectively. Thermodynamic parameters reveals the spontaneous and exothermic nature of the adsorption. The FTIR study indicates that hydroxyl groups, NH4+ ions and NO3- ions on MKC surface play a key role in Cr(VI) adsorption. The Cr(VI) desorbability of 86.53% is achieved at a Na2CO3 solution. The results show that MKC is suitable as a low-cost adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH close to that where pollutants are usually found in the environment.
DENG Lin(邓林)1, 2, SHI Zhou(施周)1, 2, LUO Lu(罗璐)1, 2, CHEN Shi-yang(陈世洋)1, 2, YANG Ling-fang(杨灵芳)1, 2, YANG Xiu-zhen(杨秀贞)1, 2, LIU Li-shan(刘立山)1, 2
(1. Department of Water Engineering and Science, College of Civil Engineering,
Hunan University, Changsha 410082, China;
2. Key Laboratory of Building Safety and Energy Efficiency of Ministry of Education (Hunan University),
Changsha 410082, China)
Abstract:A low-cost adsorbent modified kaolin clay (MKC) was synthesized and utilized for Cr(VI) removal from aqueous solution. Adsorption experiments were carried out as a function of adsorbent dosage, solution pH, Cr(VI) mass concentration, contact time, electrolyte, and temperature. It is found that the adsorption efficiency is high within a wide pH range of 2.5-11.5, and equilibrium is achieved within 180 min. Increases in temperature and electrolyte concentration decrease the adsorption. The adsorption follows the pseudo-second-order kinetic model. The Langmuir isotherm shows better fit than Freundlich isotherm. The maximum uptake capacities calculated from the Langmuir model are 15.82, 15.55 and 15.22 mg/g at 298, 308 and 318 K, respectively. Thermodynamic parameters reveals the spontaneous and exothermic nature of the adsorption. The FTIR study indicates that hydroxyl groups, NH4+ ions and NO3- ions on MKC surface play a key role in Cr(VI) adsorption. The Cr(VI) desorbability of 86.53% is achieved at a Na2CO3 solution. The results show that MKC is suitable as a low-cost adsorbent for Cr(VI) removal which has higher adsorption capacity and faster adsorption rate at pH close to that where pollutants are usually found in the environment.
Key words:kaolin clay; adsorption; Cr(VI); kinetics; isotherm; thermodynamics; desorption