Unlü Nuri, Ersoz Mustafa
Department of Chemistry, Faculty of Arts and Sciences, University of Selcuk, Konya, Turkey.
J Hazard Mater. 2006 Aug 21;136(2):272-80. doi: 10.1016/j.jhazmat.2005.12.013. Epub 2006 Jan 25.
In this study, the adsorption conditions of Cu(II), Pb(II) and Cd(II) metal ions onto sporopollenin have been studied. The different variables effecting the sorption capacity such as pH of the solution, adsorption time, initial metal ion concentration and temperature have been investigated. Adsorption isotherms correlated well with the Freundlich type adsorption isotherm and adsorption capacities were found to be 0.0195, 0.0411 and 0.0146 mmol g(-1) for Cu(II), Pb(II) and Cd(II) metal ions, respectively. Experimental data were also evaluated to find out kinetic characteristics of the adsorption process. Adsorption processes for three target heavy metal ions were found to follow pseudo-second order type adsorption kinetics. Intraparticle diffusion was found to take part in adsorption processes but it could not be accepted as the primary rate-determining step. The mean free energies of adsorption (E) were found to be between 8 and 16 kJ mol(-1) for the metal ions studied and therefore adsorption mechanism for the adsorbent was explained as an ion-exchange process. But it was observed that chelating effect is also playing an important role in the adsorption of metal ions onto sporopollenin. Thermodynamic parameters, DeltaH degrees , DeltaS degrees and DeltaG degrees were also calculated from graphical interpretation of the experimental data. Standard heats of adsorption (DeltaH degrees ) were found to be endothermic and DeltaS degrees values were calculated to be positive for the adsorption of Cu(II), Pb(II) and Cd(II) ions onto the adsorbent. Negative DeltaG degrees values indicated that adsorption process for these three metal ions onto sporopollenin is spontaneous.
在本研究中，已对孢粉素对铜（II）、铅（II）和镉（II）金属离子的吸附条件进行了研究。已考察了影响吸附容量的不同变量，如溶液的pH值、吸附时间、初始金属离子浓度和温度。吸附等温线与弗伦德利希型吸附等温线相关性良好，发现铜（II）、铅（II）和镉（II）金属离子的吸附容量分别为0.0195、0.0411和0.0146 mmol g⁻¹。还对实验数据进行了评估，以找出吸附过程的动力学特征。发现三种目标重金属离子的吸附过程遵循准二级吸附动力学。发现颗粒内扩散参与了吸附过程，但不能将其视为主要的速率决定步骤。对于所研究的金属离子，发现吸附平均自由能（E）在8至16 kJ mol⁻¹之间，因此吸附剂的吸附机理被解释为离子交换过程。但观察到螯合效应在金属离子吸附到孢粉素上的过程中也起着重要作用。还通过对实验数据的图形解释计算了热力学参数ΔH°、ΔS°和ΔG°。发现吸附标准热（ΔH°）为吸热，对于铜（II）、铅（II）和镉（II）离子吸附到吸附剂上，计算出的ΔS°值为正值。负的ΔG°值表明这三种金属离子在孢粉素上的吸附过程是自发的。
