Department of Mining Engineering and Natural Resources, Universitat Politècnica de Catalunya, Av. Bases de Manresa, 61-73, 08240, Manresa, Barcelona, Spain.
J Hazard Mater. 2012 Mar 30;209-210:343-7. doi: 10.1016/j.jhazmat.2012.01.036. Epub 2012 Jan 21.
Chromium plating used for functional purposes provides an extremely hard, wear and corrosion resistant layer by means of electrolytic deposition. Typical layer thicknesses range between 2.5 and 500 μm. Chromium electroplating baths contain high concentrations of Cr(VI) with chromium trioxide (CrO(3)) as the chromium source. When because of technical or economic reasons a bath gets exhausted, a waste containing mainly chromium as dichromate as well as other heavy metals is generated. Chromium may then be purified for use in other industrial processes with different requirements. In this work, a sustainable system for using galvanic wastes as reagents in the leather tanning industry, thus reducing quantity of wastes to be treated, is presented. Metal cations present in the chromium exhausted bath were precipitated with NaOH. Then, the solution containing mainly soluble Cr(VI) was separated. By means of sodium sulphite in acidic conditions, Cr(VI) was reduced to Cr(III) as chromium (III) sulphate. From chromium (III) sulphate a basic Cr(III) sulphate may be obtained, which is one of most used compounds in the tanning industry. Cr(III) concentration in the final solution allows its reuse without concentration, but with a slight dilution.
镀铬用于功能目的，通过电解沉积提供极其坚硬、耐磨和耐腐蚀的涂层。典型的层厚度在 2.5 到 500 微米之间。镀铬电解液含有高浓度的六价铬，其中三氧化铬 (CrO(3)) 是铬的来源。由于技术或经济原因，当镀液耗尽时，会产生一种主要含有重铬酸盐以及其他重金属的废物。然后，可以将铬纯化并用于其他具有不同要求的工业过程中。在这项工作中，提出了一种可持续的系统，将电镀废物用作制革工业中的试剂，从而减少需要处理的废物量。用氢氧化钠沉淀铬耗尽镀液中的金属阳离子。然后，分离出主要含有可溶性六价铬的溶液。在酸性条件下用亚硫酸钠将六价铬还原为三价铬，生成硫酸铬。从硫酸铬中可以得到碱式硫酸铬，它是制革工业中最常用的化合物之一。最终溶液中的铬 (III) 浓度允许其在不浓缩的情况下重复使用，但需要稍加稀释。
