Cavaco Sofia A, Fernandes Sandra, Augusto Cátia M, Quina Margarida J, Gando-Ferreira Licínio M
Department of Chemical Engineering, University of Coimbra, Pólo II, 3030-790 Coimbra, Portugal.
J Hazard Mater. 2009 Sep 30;169(1-3):516-23. doi: 10.1016/j.jhazmat.2009.03.129. Epub 2009 Apr 5.
In this study two chelating resins containing iminodiacetic acid groups (Amberlite IRC 748 and Diaion CR 11) and a chelating resin based on sulfonic and diphosphonic acid groups (Diphonix) were investigated in order to separate Cr(III) from industrial effluents produced in hard and decorative electroplating. Samples of two industrial plants were characterized during a period of about one year and a half in terms of the metals content (Cr, Cu, Na, Ca, Fe and Ni), Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Chemical Oxygen Demand (COD) and pH. Some of the physical properties of the resins, namely the moisture content, apparent density, intraparticle porosity and the particle size distribution were also evaluated. To quantify the sorption capacity of the resins, batch experiments were performed using synthetic solutions of Cr(III), as well as solutions of Fe in the case of Diphonix. The Langmuir and Langmuir-Freundlich isotherms enabled a good description of the ion-exchange equilibrium data, and the maximum sorption capacity determined for Amberlite and Diaion was 3.6 mequiv./g(dry resin). For Diphonix that parameter was 3.4 mequiv./g(dry resin). The Diphonix resin exhibits a high selectivity for transition metals (Fe, Ni) over the chromium trivalent. Therefore, it was screened as the most suitable for selectively removing those metal impurities from chromium electroplating effluents. For this resin, the sorption capacity is strongly dependent on the initial pH of the solution. Though, high regeneration efficiencies of Diphonix for stripping Cr(III) were found by using a mixture of NaOH/H(2)O(2). The mathematical model tested for describing the dynamics of the process allowed a good fitting to the experimental data and enabled the estimation of effective pore diffusivity of Cr(III). The saturations of Diphonix with industrial effluents demonstrated that the breakthrough capacity of the resin is affected by the presence of other species in solution, such as Fe and Ni. Nevertheless, these effluents may be treated with this resin, being possible to separate Cr(III) from other transition metallic ions in solution.
在本研究中，对两种含亚氨基二乙酸基团的螯合树脂（Amberlite IRC 748和Diaion CR 11）以及一种基于磺酸和二膦酸基团的螯合树脂（Diphonix）进行了研究，目的是从硬铬电镀和装饰性电镀产生的工业废水中分离出Cr(III)。在大约一年半的时间里，对两家工厂的样品进行了金属含量（Cr、Cu、Na、Ca、Fe和Ni）、总悬浮固体（TSS）、总溶解固体（TDS）、化学需氧量（COD）和pH值的表征。还评估了树脂的一些物理性质，即含水量、表观密度、颗粒内孔隙率和粒度分布。为了量化树脂的吸附容量，使用Cr(III)的合成溶液以及Diphonix树脂在Fe存在情况下的溶液进行了批量实验。Langmuir等温线和Langmuir-Freundlich等温线能够很好地描述离子交换平衡数据，Amberlite和Diaion树脂的最大吸附容量为3.6 mequiv./g（干树脂）。Diphonix树脂的该参数为3.4 mequiv./g（干树脂）。Diphonix树脂对过渡金属（Fe、Ni）的选择性高于三价铬。因此，它被筛选为最适合从镀铬废水中选择性去除这些金属杂质的树脂。对于这种树脂，吸附容量强烈依赖于溶液的初始pH值。不过，通过使用NaOH/H₂O₂混合物发现Diphonix树脂对Cr(III)的再生效率很高。用于描述该过程动力学的数学模型与实验数据拟合良好，并能够估算Cr(III)的有效孔扩散率。用工业废水使Diphonix树脂饱和的实验表明树脂的穿透容量受溶液中其他物质（如Fe和Ni）的影响。然而，这些废水可以用这种树脂处理，从而有可能从溶液中的其他过渡金属离子中分离出Cr(III)。
