Detection Of Hexavalent Chromium Ion Content In The Dark Leather

Because of the influence from the color of dyestuffs, the determination of sexivalent chromium (Cr(VI)) in deep-colored leathers and wastewater is a difficult problem. No determination method may be recognized or accepted both at home and abroad.The toxicity of Cr(VI) is more than one hundred times of that of Cr(III). Sexivalent chromium may do harmful to the skins, and carcinogenesis or damage to the skins may be caused by sexivalent chromium. So the studies on the formation, determination, and prevention of Cr(VI) in finished leathers is one of the problems facing the leather industry. In the recent years, more and more strict regulations are applied for the soluble chromium in leathers by Western Europe and Australia. Generally, the need for soluble chromium in leathers is less than 10 ppm. In some more strict regulations, the need may be less than 2 ppm.China is a big country in leather-making. The problem of sexivalent chromium in leathers is widespread. With the entrance of WTO of China, leather export trade increases, and the detection and prevention of sexivalent chromium in leathers become more and more important and urgent.Nowadays, the commonly testing method of sexivalent chromium in leathers is IUC-18 standard method. There are still some disadvantages in the method, and one of them is that the result may be easily affected by the color of the extraction solutions. And, as a result, no exact value may be obtained. The reference value, which is 3mg/kg, is usually hard to achieve. Therefore, some modifications of the method should be done to get a new method, which may be more exact.In this paper, active carbon is employed as sorbent and de-coloring agent. The influencing laws of pH on the adsorption of active carbon for sexivalent chromium and dyestuff are discussed. When the pH is more than 11.0, the adsorption of active...