Chrome tanning is one of the popular tanning methods followed globally that generates considerable level of chromium pollution in the resulting e uent. The existing conventional chrome tanning system has to be modi ed to increase the exhaustion level of chromium in the tanning process. In the present investigation, a protein based product has been developed from raw trimming wastes and applied in chrome tanning process to enhance the exhaustion level of chromium. The experiment conducted using the product at the level of 6% exhibited chromium exhaustion at the level of 93% in the process. FT-IR analysis revealed the presence of peaks for various functional groups namely carboxylic acids, aldehyde, amide and hydroxyl groups for the high exhaust chrome tanning. The shrinkage temperature of the experimental leather was found to be more than 100 o C. Results of microscopic studies from SEM-EDX revealed that enhanced adsorption of chromium up to a level of 5.24 weight % containing chromium with atomic % 1.27 in the sample of 6% co-polymer. AFM images also show increase in adsorption of chromium with increased amount of co-polymer in the solution. Increased interactions between active sites of collagen-complex and chromium resulted into improved exhaustion of chromium as revealed from higher intensities of XRD images. CD spectra revealed that the addition of protein based product increased the ellipticity of the collagen in the experimental sample as compared to control sample. The crust leather showed improved colour, organoleptic and comparable strength properties of the experimental leather.

A method of dehairing of goat skins using oxidative chemicals and protease enzyme has been attempted. Dehairing process is one of the important and essential steps in the leather making, where hair is removed by lime and sodium sulphide in the conventional process. This conventional dehairing system generates higher amount of pollution problem as compared to the other unit operations and unit processes. In this work, dehairing of the goat skins through oxidative agent namely magnesium peroxide and protease enzyme were useful for dehairing of goat skins. For this, protease have been produced from Bacillus sp. at laboratory level and the activity was found out. The dehairing of goat skins takes place for the duration of 14–16 hours. The leather produced with the experimental sample showed comparable organoleptic and strength properties with the conventional sample. This method paved the way for reduction of pollution loads especially BOD, COD and TDS to the level of 59, 27 and 77% respectively in comparison with the control sample. The reaction kinetics for the formation of the ligand-macromolecular complex is found from the Isothermal titration calorimetry (ITC) experiment and mathematical model has been formulated. The dyed crust leather showed comparable colour properties. In addition to that, there is reduction in processing time for leather making through skipping reliming and deliming processes which is said to be another advantage of this method. The physical strength properties of the experimental leather were also comparable with conventionally produced leather.