title: A comparative study of Ag(I) adsorption on raw and modified spent grain: kinetic and thermodynamic aspects.
abstract: 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 (Ea) 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.
authors.affiliation: School of Metallurgical Science and Engineering, Central South University, Changsha, PR China.
authors.forename: Qingzhu
authors.initials: Q
authors.lastname: Li
authors.forename: Liyuan
authors.initials: L
authors.lastname: Chai
authors.forename: Zhihui
authors.initials: Z
authors.lastname: Yang
authors.forename: Qingwei
authors.initials: Q
authors.lastname: Wang
authors.forename: Yunyan
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D002523:Edible Grain / Q000737:chemistry*; D007700:Kinetics; D012834:Silver / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D012834:Silver