title: Adsorption of cesium from aqueous solution using agricultural residue--walnut shell: equilibrium, kinetic and thermodynamic modeling studies.
abstract: A novel biosorbent derived from agricultural residue - walnut shell (WS) is reported to remove cesium from aqueous solution. Nickel hexacyanoferrate (NiHCF) was incorporated into this biosorbent, serving as a high selectivity trap agent for cesium. Field emission scanning electron microscope (FE-SEM) and thermogravimetric and differential thermal analysis (TG-DTA) were utilized for the evaluation of the developed biosorbent. Determination of kinetic parameters for adsorption was carried out using pseudo first-order, pseudo second-order kinetic models and intra-particle diffusion models. Adsorption equilibrium was examined using Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms. A satisfactory correlation coefficient and relatively low chi-square analysis parameter χ(2) between the experimental and predicted values of the Freundlich isotherm demonstrate that cesium adsorption by NiHCF-WS is a multilayer chemical adsorption. Thermodynamic studies were conducted under different reaction temperatures and results indicate that cesium adsorption by NiHCF-WS is an endothermic (ΔH° > 0) and spontaneous (ΔG° < 0) process.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Dahu
authors.initials: D
authors.lastname: Ding
authors.forename: Yingxin
authors.initials: Y
authors.lastname: Zhao
authors.forename: Shengjiong
authors.initials: S
authors.lastname: Yang
authors.forename: Wansheng
authors.initials: W
authors.lastname: Shi
authors.forename: Zhenya
authors.initials: Z
authors.lastname: Zhang
authors.forename: Zhongfang
authors.initials: Z
authors.lastname: Lei
authors.forename: Yingnan
authors.initials: Y
authors.lastname: Yang
mesh_terms: D000327:Adsorption; D000383:Agriculture; D002586:Cesium / Q000302:isolation & purification*; D004055:Differential Thermal Analysis; D004058:Diffusion; D005295:Ferrocyanides / Q000737:chemistry; D031324:Juglans; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D008962:Models, Theoretical; D009532:Nickel / Q000737:chemistry; D017711:Nonlinear Dynamics; D012996:Solutions; D013816:Thermodynamics; D013818:Thermogravimetry; D013997:Time Factors; D014866:Waste Products / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D005295:Ferrocyanides; D012996:Solutions; D014866:Waste Products; D014874:Water Pollutants, Chemical; C027325:nickel ferrocyanide; D002586:Cesium; D009532:Nickel