Process Safety and Environmental Protection, Vol.100, 36-48, 2016
Green remediation of sulfide in oxidative dehairing of skin and correlation by mathematical model: An eco-friendly approach
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. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Keywords:Oxidative dehairing;Sodium percarbonate;Mathematical modeling;Reduction of pollution loads;Replacement of hazardous chemical of sodium sulfide