Research advances in the fabrication of biosafety and functional leather: A way-forward for effective management of COVID-19 outbreak.

With the recent events following the pandemic COVID-19, global awareness about the use of biosafety materials has been in raise. Leather industry being a major commodity-driven sector, its role in addressing the issues concerning the safe use of leather products has become inevitable for the sustainability of the industry. A significant number of researches have been conducted to fabricate bio-safe leather by incorporating different types of antimicrobial agents during leather manufacturing. Besides, the increasing diversity in the development of synthetic materials and the impact of COVID-19 outbreak on automotive industry may create more demand from customers for incorporating different functionalities in leather without losing its inherent properties. Some of the key functionalities discussed include resistance to microbial growth, self-cleaning through superhydrophobicity and photocatalysis, thermal regulation, flame retardance and scented leather. This review focusses on the fabrication of such advanced functional leather materials over the past decade with special emphasis on antimicrobial leather. Some of the key factors elaborated in the review include the state of art approaches for the preparation of functional materials, mode of incorporation of the same into the leather matrix, the mechanism behind with a perspective on the challenges involved in fabrication for real-world applications. A major outcome of this review is that even though several kinds of cutting edge researches are happening in the field of leather manufacturing, most of them were not validated for its practical applicability and sustainability of the proposed solution. This could be majorly attributed to the cost involved in fabrication of such materials, which forms a crucial factor when it comes to a mass production industry such as leather. Also, the researchers should concentrate on the toxicity of the fabricated materials which can impede the process of adopting such emerging and need of the hour technologies in the near future. Knowledge obtained from this review on fabrication of bio-safety leather against bacteria, mold and fungi would help further to integrate the antiviral property into the same which is a global need. Also, fabrication of functionalized leather would open new avenues for leather manufactures to venture into the development of advanced leather products such as flexible electronics, radiation shielding and fire fighting garments etc.

Leather solid waste: An eco-benign raw material for leather chemical preparation - A circular economy example.

One of the long lasting problems associated with leather industry is to meet environmental standards for both liquid and solid wastes. Statistics show that one tonne of wet-salted hides/skins yields around 650 kg of solid waste. Among various wastes generated, trimmings for the most part have been underutilized. Collagen presents in trimmings waste are effectively used but hair goes unutilized or at the most as feed for boilers during gelatin manufacturing. Hence, newer technology is needed for complete and effective utilization of raw trimmings. In leather manufacture, formaldehyde condensates polymers are used as re-tanning agent to enhance the compaction of leather. However, these products are hard for biodegradation and also cause the release of free formaldehyde in leather, which is a known carcinogen. Here, there is a need for development of formaldehyde free re-tanning agent for eco-benign leather processing. In this work an attempt had been made to develop formaldehyde free biodegradable eco-benign re-tanning agent from raw trimming of tannery solid waste as a circular economy model. Alkaline (7.5%w/w NaOH) - hydrogen peroxide (10%w/w) pre-treatment followed by thermal hydrolysis at 100 °C for 5 h was an optimized method for effective hydrolysis of trimmings and the process of preparation of product results in the holistic utilization of raw trimmings. The developed product was characterized using Dynamic light scattering and FTIR techniques. The product prepared was further used in leather manufacture as a re-tanning agent and was found to impart multifunctional properties to leathers such as fullness, grain tightness and shade of dye brilliance. Product improves the mechanical strength characteristics of leather and also the exhaustion of post-tanning chemicals. SEM analysis shows that the experimental leather is more compact and flat than control. This novel strategy had not only solved the issue of solid waste but also resulted in a greener leather auxiliary leading to greener environment.

A logical and sustainable approach towards bamboo pulp bleaching using xylanase from Aspergillus nidulans.

Driven by the environmental benefits that bio-bleaching could bring, the interest in xylanase has received enormous attention and hence, the search of xylanase with properties like no cellulase activity, function at elevated temperatures and pH continues. The present study reports the production of extracellular xylanase from Aspergillus nidulans using waste agro-residues as substrate. The optimum temperature (60 °C) and pH (9.0), classified the xylanase as thermo and alkali tolerant. The addition of salt of Mn2+ increased the xylanase activity to almost double; however, these ions were unable to protect the enzyme from thermal inactivation. The FTIR spectra of bamboo pulp treated with this xylanase, revealed reduction in lignin as evident from reduced peak intensity coupled with the reduction in kappa number. The SEM image of enzyme treated pulp, exhibited dissociation in fibers exposing the internal structure with slight roughness. Swelling was also observed there by increasing its thickness which eventually helped in improving its physical properties. The bleaching efficacy of indigenous xylanase as indicated in this study, has established its competence as a promising candidate for pre-treating the bamboo pulp.

Effect of zirconium(IV) complexes on the thermal and enzymatic stability of type I collagen.

Understanding the mechanism of stabilization of collagen is an important area of research. Metal ions are known to interact with collagen and bring about the stability of the same. In the present investigation, the interaction of zirconium(IV) complexes with collagen was studied. The effect of zirconium(IV) complexes, namely zirconium oxychloride and zirconium oxalate on the enzymatic and thermal stability of collagen was investigated. Zirconium has been found to increase the hydrothermal stability of the rat tail tendon (RTT) collagen fibers to about 8-10 degrees C more than that of the native collagen. The order of stabilization of zirconium(IV) complexes is zirconium oxychloride>zirconium oxalate. This could be due to the differences in the type of interaction with collagen, which is also reflected in the differences in the conformational changes of collagen brought about by the two complexes. Zirconium oxychloride, which forms tetrameric species in solution, has been shown to have better crosslinking with collagen as seen from viscometry studies and hence provides better enzymatic stability to collagen than zirconium oxalate, which largely forms monomeric species in solution.