Recycling of tannery fleshing waste by a two step process for preparation of retanning agent

Abstract Discharge of huge quantities of fleshing wastes by leather industries has raised serious concerns on account of their environmental impacts. Limed fleshings, a hazardous solid waste produced from leather making process is rich in proteins and lipids. Currently, fleshing waste is not properly utilized and disposed off in unsecured manner. Utilization of fleshings for preparation of value added chemicals provide practically feasible and economically viable solution. This study investigates the feasibility of using fleshings as resource material for preparation of retanning agent by a two step process aiming at recycling of the waste. The fleshings was initially hydrolysed using Bacillus subtilis protease followed by polymerization with methacrylic acid. The performance of the resulting fleshings hydrolysate-acrylic polymer (FHAP) was assessed as retanning agent. The FHAP treated leather exhibited better fullness, grain tightness and smoothness than control leather and also improved the strength properties of the leather. SEM results revealed that the treated leather showed more cemented fiber bundles due to the efficient filling of interfibrillar space of the leather, which was confirmed by air permeability analysis. Thus, preparation of FHAP for retanning application offers sustainable solution to the problem of fleshing waste management and also an appropriate strategy for circular economy.