Investigation of 60Co Gamma Irradiation as a Technique for Leather Processing

Abstract

Leather industry is considered an eco-friendly industry because it converts meat by-products which would have otherwise been thrown into other landfills, into precious eco-benign products. Environmental implications related to this industry during processing present bleak prospects. However, green chemistry has been earmarked as a potential measure to curtail pollution though the quality of the resultant leather is inferior to that of synthetic processing. Therefore, measures to enhance the viability of green chemistry leather processing are necessary. Gamma radiation coupled with vegetable tanning agents is a viable processing method to improve leather properties and strength. Proper preservation and processing of hides and skins in the tannery determines the quality of the final product. In this study, seven samples (100 g) were cut, and one sample was preserved with bactericide, while the other six were irradiated with different doses of gamma radiation (0, 10, 20, 30, 40, and 50 kGy) using 60Co gamma irradiator Model GC 220E. Isolation of bacterial load was done for all samples and colony-forming units (CFU) were counted using plate count method. The remaining hide proceeded for processing up to pickling stage where the hide was cut into two halves along the backline. Both halves were cut into equally smaller samples for irradiation and then tanned using mimosa tannins and chromium salts. Dog-bone-shaped samples cut parallel and perpendicular to the backline from the irradiated pelt were tested for tensile properties using the Instron Testing Machine, Model 1101. The effect of sampling direction, tanning agents, and gamma radiation on the tensile properties was determined. Leather samples of dimension 30 mm 9.3 mm 0.93 mm were aged in a heat-adjustable cabinet at 80 for 24 hours and UV- cabinets (UV-C, 254 nm) for 144 hours and conditioned for 48 hours in a normal atmosphere before Dynamic Mechanical Analysis tests. The effect of gamma radiation on viscoelastic properties and photo and thermal stability of both chrome and mimosa-tanned leather was determined. The microbial load of hide treated with bactericide was reduced and when irradiated at 10 kGy of radiation, there was a significant reduction. The tensile strength was increased up to 30 kGy dose of radiation for both chrome and mimosa-tanned leather. On the other hand, the thermal and photostability of both leathers showed some variation with increasing doses of radiation. Gamma radiation as compared to bactericide reduced the microbial load of hides significantly contributing to a cleaner preservation approach of hides and skins in tanneries. Doses of up to 30 kGy induce additional crosslinks to the leather thus enhancing the strength and stability of the processed leather. Thus, this study recommends the incorporation of gamma radiation during leather processing.