Mathematical modeling of bovine hides swelling behavior by response surface methodology for minimization of sulfide pollution in leather manufacture

Excessive utilization of such sulfides as sodium sulfide always results in serious wastewater pollution in the liming processing of leather manufacture, and thus the critical or optimal consumption of sodium sulfide is necessary. In this work, it was found that the swelling behavior of bovine hides is highly dependent on the liming time as well as temperature and the sodium sulfide concentration. In order to understand the swelling mechanism and optimize the swelling condition, a mathematical model was built based on the response surface methodology (RSM). As a result, the predicted values (Pva) were in good agreement with the experimental values (Eva) by analyzing the absolute as well as relative errors, and the optimized operation conditions were found to be performed in 0.85 wt% Na2S solution at 25 °C for 895 min, by which the polysaccharides in hair follicle are dissolve completely and meanwhile the collagen fiber bundles are swollen and disperse very well.