Adsorption of hexavalent chromium onto kaolin clay based adsorbent

作者：Deng Lin; Shi Zhou^*; Luo Lu; Chen Shi-yang; Yang Ling-fang; Yang Xiu-zhen; Liu Li-shan

来源：Journal of Central South University (English Edition), 2014, 21(10): 3918-3926.

DOI：10.1007/s11771-014-2379-4

• kaolin clay
• adsorption
• Cr(VI)
• kinetics
• isotherm
• thermodynamics
• desorption

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.

• 出版日期2014-10
• 单位湖南大学