Green remediation of sulfide in oxidative dehairing of skin and correlation by mathematical model: An eco-friendly approach

• Oxidative dehairing with sodium-percarbonate replacing hazardous sodium sulfide investigated.
• Pollution reduction in BOD, COD, TSS were reduced up to the level of 56.3, 62.5, 68.1, and 52%.
• Model describing reaction–diffusion kinetics with monolayer adsorption using Langmuir.
• Improved color properties are obtained in experiments with comparable leather qualities.
• Reduction of total processing time in experiments by eliminating reliming and deliming processes.

The dehairing of goat skin using sodium percarbonate has been attempted in place of conventional dehairing using lime and sodium sulfide. Conventional dehairing generates huge pollution loads to the maximum level in leather processing. The present method is very simple that dehairs the goat skin with the help of 5% sodium percarbonate at an optimum level in combination with 4% sodium hydroxide and replaces hazardous material like sodium sulfide. The complete dehairing was achieved in 16 h duration. The pollution loads in terms of BOD, COD, Total Dissolved Solids (TDS), and Total Suspended Solids (TSS) were reduced up to the level of 56.3, 62.5, 68.1, and 52% in comparison with the control sample. Reduction of TOC values has been noticed. The advantage of the method lies with the fact that the processing time for leather making is considerably reduced by skipping reliming and deliming unit processes. A mechanistic mathematical model describing the diffusion reaction phenomena of dehairing agent through pores of skin has been developed that supports monolayer adsorption by Langmuir isotherm. Thermo gravimetric analysis and differential scanning calorimetry results explain that the present unit operation is dominated by exothermic process. Experimental samples show improved uptake of color with comparable leather qualities.

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