High Exhaustion of Chrome Tan, Enhancement of Leather Properties and Reduction of Chrome Tanning Effluent Impact

THE LEATHER industry faces very challenging task because of the regulations enforced I by the various pollution control bodies to maintain the discharged norms of the chemical in the treated water. From an environmental stand point, one of the most significant waste is the chromium species because it posses a serious disposal problem to human health and the environment. Therefore, chrome tan effluent is critically analyzed for the harmful effects due to the incomplete exhaustion of the hazardous chrome cations in tanning bath. The paper has focused on the challenges/impacts of chrome tanning effluent and evaluates the alternative treatment options. Reducing agents namely; sodium bisulphite (NaHSO3), sodium thiosulphate (Na2S2O3) in connection with hydroxy carboxylic acids and /or basifying agents were used to enhance the exhaustion, fixation of chrome tan and shrinkage temperature as well as strength properties of the tanned leather. In addition, the leather quality is one of the important factors taking into consideration. The optimum conditions for exhaustion, fixation, shrinkage temperature as well as leather quality showed that both NaHSO3 and Na2S2O3 have a similar effect in connection with basic oxide of 1.5% magnesium oxide (most effective one) and the best modifying agent is tartaric acid (3%), temperature of 35 degrees C. The best results obtained are 93.51% exhaustion, 93.71% fixation and 121 degrees C shrinkage temperature in aqueous medium. The present work was devoted to change the primary condition of tanning process based on the modification of pelt to increase the high exhaustion of chrome tan which consequently, leads to lower the levels of unused chrome in the tanning effluent and minimized the deficit existing from the environmental point of view. The obtained results showed that, over 90% reduction of the chrome concentration in effluent and 80% reduction of the COD. The assessment was demonstrated that the modification process exhaust, and fixed of chrome tan, improve leather properties, reduced the environmental impact and at the same time saves energy and time than the traditional one.