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A Comparative Study of Ag(I) Adsorption on Raw and Modified Spent Grain: Kinetic and Thermodynamic Aspects
Author(s) -
Li Qingzhu,
Chai Liyuan,
Yang Zhihui,
Wang Qingwei,
Wang Yunyan
Publication year - 2010
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143010x12681059116978
Subject(s) - adsorption , endothermic process , exothermic reaction , exothermic process , chemistry , langmuir adsorption model , kinetic energy , monolayer , aqueous solution , kinetics , activation energy , gibbs free energy , thermodynamics , chemical engineering , organic chemistry , physics , biochemistry , quantum mechanics , engineering
The capability of modified spent grain (MSG) to adsorb silver (I) [Ag(I)] from aqueous solution was investigated and compared with raw spent grain (RSG) regarding their adsorption isotherms, kinetics, and thermodynamics. The monolayer adsorption capacity was 30.28 mg/g for RSG and 158.23 mg/g for MSG according to the Langmuir isotherm. The Ag(I) adsorption on MSG was approximately 4 times higher than that on RSG. The pseudo‐second‐order kinetic model provided the best description of Ag(I) adsorption on the two adsorbents. The calculated activation energy ( E a ) implies that the adsorption of Ag(I) on RSG is a physical adsorption and on MSG is of a chemical nature. Thermodynamic results suggest that the adsorption of Ag(I) is an exothermic process for RSG and an endothermic process for MSG, whereas both adsorption processes are spontaneous in nature.