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The purification of spent chromium plating solutions using an electrolytic system.

机译：使用电解系统纯化废铬电镀液。

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EPA's pollution prevention and waste reduction policies encourage the regeneration and recycling of spent chromium plating baths. One approach used successfully in the past is electrolytic regeneration. The efficiency of this process depends on the efficiency of the removal of contaminants from anolyte, which depends on the type of electrode used, the amount of applied current, and the types of separators used. Among these factors, the type of separator used is most important because transport of the impurity through the separator is crucial for the electrolytic regeneration processes to be successful.; The transport properties of the impurities (Cu(II), Ni(II), and Fe(III)) through the separators used in these processes are poorly understood. Therefore, in this research, studies of the transport properties (diffusivity, conductivity, and mobility) of contaminants through the separators (Nafion 117 membrane and ceramic diaphragm) were investigated. The partition coefficients of the contaminants in the separators were also determined since they impact their transport rate. For the Cu(II), Ni(II), and Fe(III) in the Nafion membranes, their partition coefficients were 0.6, 0.59, and 0.51, respectively in single ion partitioning experiments; 0.57, 0.58, and 0.40, respectively in multiple ion partitioning experiments. The partition coefficients of bisulfate and Cr(VI) in the Nafion membrane were about 0.21 and 0.14, respectively.; It was found that partitioning was well characterized by a Freundlich isotherm. In the Nafion membrane, cationic partitioning decreased with decreasing pH. The partition coefficients of the three impurity species in the ceramic diaphragm were approximately the same (0.4). Trivalent impurity cations had a higher affinity for the Nafion membrane than divalent cations. This partly accounted for that the trivalent cation (Fe(III)) having smaller diffusion coefficients than the divalent cations. The diffusivities measured were in the order of Cu(II) > Nii(II) > Fe(III) in both separators. For the Nafion membrane, they were 1.04 × 10−6, 8.36 × 10−7, and 4.24 × 10−7 cm 2/sec, respectively in single ion diffusion experiments; 1.18 × 10−6, 1.09 × 10−6, and 5.56 × 10−7 cm2/sec, respectively in multiple ion diffusion experiments. For the ceramic diaphragm, they were 3.64 × 10−6, 3.04 × 10−6, and 1.68 × 10−6 cm2/sec, respectively in multiple ion diffusion experiments. The diffusion coefficients of bisulfate and Cr(VI) through the Nafion membrane were 1.08 × 10−6 and 8.06 × 10−7 cm2/sec, respectively. Temperature did not affect on the cation partitioning in the Nafion membrane; however, increasing temperature increased diffusivity according to the Arrehnius equation. The impurity cation diffusivity also increased with decreasing pH. (Abstract shortened by UMI.)
机译：EPA的污染预防和减少废物政策鼓励废铬镀液的再生和再循环。过去成功使用的一种方法是电解再生。该过程的效率取决于从阳极电解液中去除污染物的效率，这取决于所用电极的类型，施加的电流量以及所用隔板的类型。在这些因素中，所用分离器的类型最为重要，因为杂质通过分离器的传输对于电解再生过程的成功至关重要。杂质（Cu（II），Ni（II）和Fe（III））通过这些工艺中使用的隔板的传输特性了解得很少。因此，在这项研究中，研究了污染物通过分离器（Nafion 117膜和陶瓷膜片）的传输特性（扩散率，电导率和迁移率）。还确定了分离器中污染物的分配系数，因为它们会影响其传输速率。对于Nafion膜中的Cu（II），Ni（II）和Fe（III），在单离子分配实验中它们的分配系数分别为0.6、0.59和0.51。在多次离子分配实验中分别为0.57、0.58和0.40。 Nafion膜中硫酸氢根和Cr（VI）的分配系数分别约为0.21和0.14。发现以弗氏等温线很好地表征了分区。在Nafion膜中，阳离子分配随着pH的降低而降低。陶瓷隔膜中三种杂质的分配系数大致相同（0.4）。三价杂质阳离子对Nafion膜的亲和力高于二价阳离子。这部分地解释了具有比二价阳离子小的扩散系数的三价阳离子（Fe（III））。在两个隔板中测得的扩散率的顺序为Cu（II）> Nii（II）> Fe（III）。对于Nafion膜，它们分别为1.04×10 -6 ，8.36×10 -7 和4.24×10 -7 cm 单离子扩散实验中分别为2 / sec； 1.18×10 −6 ，1.09×10 −6 和5.56×10 −7 cm 2 /秒，分别在多个离子扩散实验中。对于陶瓷膜片，它们是3.64×10 -6 ，3.04×10 -6 和1.68×10 -6 cm 在多次离子扩散实验中分别为2 / sec。硫酸氢根和Cr（VI）在Nafion膜上的扩散系数为1.08×10 -6 和8.06×10 −7 cm 2 /秒。温度不影响Nafion膜中的阳离子分配；但是，根据Arrehnius方程，增加温度会增加扩散率。杂质阳离子的扩散率也随着pH的降低而增加。 （摘要由UMI缩短。）

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