Polyethylene oxide (PEO) was chemically linked to natural rubber (NR) segments to form a block copolymer (BC), which proved to be a suitable material for complexing with selected first row transition metal ions in aqueous solution through batch adsorption method under noncompetitive mode. Optimum conditions for sorption were found to be 20 mmol/L initial concentration, pH at 6, ambient temperature, and 24 h. The order of decreasing adsorption capacity obtained is Mn(II) > Co(II) > Zn(II) > Ni(II) > Cu(II) > Fe(III). Freundlich isotherm shows the best fit indicating that the adsorption is of heterogeneous in nature. The complexation follows pseudo second‐order kinetics. Exothermic character of the complexation was confirmed by thermodynamic study. For all metal ions, the standard free energy change values are negative for the different temperatures studied, which confirms the spontaneous character of the process. At ambient temperature, the free energy change lies between −2.35 and − 7.83 kJ/mol for all complexes. Values of activation energy for all the metal ion complexation is within the range 11–25 kJ/mol, which indicates chemical interaction via activated physico–chemical adsorption. Variation in stability constant of the complexes also follows the same order as given above. POLYM. ENG. SCI., 60:661–672, 2020. © 2020 Society of Plastics Engineers

中文翻译：

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水性介质中3d过渡金属离子与NR / PEO嵌段共聚物的络合研究

将聚环氧乙烷（PEO）化学连接至天然橡胶（NR）链段以形成嵌段共聚物（BC），事实证明该嵌段共聚物是在非竞争模式下通过分批吸附法与水溶液中选定的第一行过渡金属离子络合的合适材料。发现最佳吸附条件为初始浓度20 mmol / L，6，环境温度和24 h下的pH。所获得的吸附能力降低的顺序为Mn（II）> Co（II）> Zn（II）> Ni（II）> Cu（II）> Fe（III）。Freundlich等温线显示最佳拟合，表明吸附本质上是异质的。络合遵循伪二级动力学。通过热力学研究证实了络合物的放热特征。对于所有金属离子，对于所研究的不同温度，标准自由能变化值是负的，这证实了该过程的自发特性。在环境温度下，所有配合物的自由能变化在-2.35和-7.83 kJ / mol之间。所有金属离子络合的活化能值在11-25 kJ / mol的范围内，这表明化学相互作用通过活化的理化吸附。配合物的稳定性常数的变化也遵循上述相同的顺序。POLYM。ENG。SCI。，60：661–672，2020.©2020塑料工程师协会