University of Tehran/Springer International Journal of Environmental Research 1735-6865 9 1 2015 01 01 Thermodynamics ofCu2+Adsorption on soilHumin 43 52 872 10.22059/ijer.2015.872 EN C.L. Li College of Resource and Environmental Science, Jilin Agricultural University, Changchun, 130118,P.R. China S. Wang College of Plant Science, Jilin Agricultural Science and Technology College, Jilin, 132101, P.R. China F. Ji College of Resource and Environmental Science, Jilin Agricultural University, Changchun, 130118,P.R. China J.J. Zhang College of Resource and Environmental Science, Jilin Agricultural University, Changchun, 130118,P.R. China L.C. Wang Institute of Agricultural Resources and Environments, Jilin Academy of Agricultural Sciences, Changchun, 130124, P.R. China Journal Article 2014 12 30 The adsorption thermodynamic characteristic of Cu2+ from aqueous solution onto humin and<br />also humic acid from a typical black soil in northeast China were examined at three different temperatures<br />(298, 318 and 338 K) by batch isotherm experiments. Results showed that humin was structurally different<br />from humic acid. The increase of temperature had a positive effect on the adsorption process. Freundlich<br />equation described the equilibrium data better with respect to Langmuir equation. Thermodynamic parameters,<br />i.e. standard free energy changes (ΔGº), standard enthalpy change (ΔHº) and standard entropy change (ΔSº),<br />revealed that Cu2+ adsorption by humin and humic acid were a feasible, spontaneous and endothermic process<br />with an increase in disorder. The values of isosteric heat of adsorption (ΔHx) increased with increasing surface<br />Cu2+ loading, and the increase in ΔHx values was smaller for humin than for humic acid. The results indicated<br />that humin and humic acid possessed energetically heterogeneous surfaces. Humic acid had greater surface<br />heterogeneity than humin https://ijer.ut.ac.ir/article_872_1de1a6c3d3d364c7a36073184fb323fd.pdf