Extraction of Oil from Tannery Fleshings for Chamois Leather Tanning

Abstract

The process of leather manufacturing produces vast amounts of solid waste annually (8.5 million tons worldwide), and most of the solid waste (80%) is produced in pre-tanning operations. The fleshing operation to remove flesh, subcutaneous tissue and natural fat from the flesh side of hide/skin (fleshings) accounts for 50-60% of total solid waste. Attempts to extract oil from the fleshings have been made, however, the application of the oils from fleshings in tanning has not been explored. The oil tanning process takes about 12 days (compared to chrome tanning which takes approximately 6 hours), and this explains why the technology is not commonly used. The objective of the research was to discover whether the fleshing oil could be used for chamois leather tanning. The oil was extracted from goat fleshings and characterised using Soxhlet extraction and chemical methods. The fat content, iodine value, acid value, percentage free fatty acid and saponification value of green fleshings were 27.56 ± 0.40%, 73.79 ± 0.34, 7.38 ± 0.13mg/g, 3.71 ± 0.06 and 187.08 ± 0.22 mg/g respectively while that of limed fleshings was 17.48 ± 0.55%, 67.40 ± 0.35, 6.08 ± 0.02mg/g, 3.06 ± 0.06 and 184.66 ± 0.33mg/g respectively. The results of the study show that the physical and organoleptic properties of fleshing oil-tanned leather were similar to those of cod oil-tanned leather. Tensile strength, elongation, tear strength and water absorption of the chamois leather were 27.88 ± 0.07N/mm2, 55.75 ± 0.17%, 56.64 ± 0.29N/mm, 211% respectively. The physical and organoleptic properties of the leathers resulting from this study suited the requirements for chamois leather.