Experimental Study on Chrome Tanned Leather Shavings Modification-Properties and Prospective for Future Application

Chrome tanned leather shavings (CTLS) are considered one of the more difficult wastes to manage in the tanning industry. At the same time, this waste is an important source of good quality collagen. The few methods described in the literature for the valorization of these wastes usually require pre-treatment or activation. In this study, an attempt was made to see if raw chrome tanned leather shavings (CTLS) could be modified to obtain secondary raw materials with new physical properties. Glutaraldehyde, glycerol, EDCs, pectin, and tannins were selected for modification of the CTLS. The effectiveness of the processes carried out was confirmed by FTIR analysis of the materials obtained. Changes in the intensity of the characteristic collagen peak (amide I, amide II, and amide III) and changes in the position of the bands in the 1200-1000 cm-1 region were observed in the recorded spectra. The modifications introduced confirmed changes in the physical properties of samples M1-M5, including an increase in bulk density from 0.15 to 0.59 g cm-3, and improved tensile strength is some cases. The elemental content results of the samples tested showed the resulting modified CTLS were free of Cd, Hg, Pb, and Cr(VI). It was also confirmed tanning waste contained significant amounts of various valuable elements. The research also included preliminary tests to assess the environmental impact of the modified materials. In a phytotoxicity test conducted on modified CTLS, M1 with pectins showed the highest root stimulation (105%), while samples with glutaraldehyde and unmodified CTLS showed significant root inhibition (75%, 74%). Other samples showed moderate plant toxicity and seed germination was not significantly affected.