Biodegradation of Leather Waste by Enzymatic Treatment

The treatment of shavings,trimmings and splits of leather waste from tanneries has a potential to generate value-added products. In this study enzymatic treatment of leather waste was performed. This method utilizes alkaline protease produced by Bacillus subtilis in our laboratory by submerged fermentation. Optimum conditions of pH,time duration,temperature and concentration of enzyme were determined for maximum degradation of leather waste. The amount of degradation was measured by the release of amino acid hydroxyproline. Amino acid composition in the hydrolysate obtained by the enzyme hydrolysis was determined. This relative simple biotreatment of leather waste may provide a practical and economical solution.

Leather waste as precursor to prepare bifunctional catalyst for alkaline and neutral zinc-air batteries

Carbon materials derived from biomass waste are considered as potential electrocatalysts for applications in zinc-air batteries(ZABs)due to their low cost and good catalytic activity.Here,we reported the preparation of gel-based catalysts through utilizing hydrolyzed waste leather powder cross-linked with metallic salt solutions.After calcination,iron-nickel alloy anchored in nitrogen-doped porous carbon catalysts(Fe Ni@NDC)was achieved.Compared with commercial Pt/C catalyst,Fe Ni@NDC-800 exhibited lower E_(1/2)(0.77 V)and better durability.More importantly,the resulting Fe Ni@NDC-800-based alkaline ZABs achieved power density of 93.01 m W/cm^(2) and open circuit voltage of 1.45 V,which the Fe Ni@NDC-800-based neutral ZAB displayed a charge/discharge cycle stability of 275 h.This work opens up the possibility of rational design and preparation of low-cost and high-performance electrocatalysts from recyclable leather waste.

Regenerating leather waste for flexible pressure sensing applications

Pressure sensor can be applied in a wide range of fields,such as voice recognition,human motions detection and artificial electronic skin,the sensing of which is greatly influenced by the flexibility and stretchability of substrate materials.Here,based on the piezoresistive effect,new kinds of flexible pressure sensors have been realized from a pair of flexible and biocompatible collagen films:one is coated by silver nanowires(Ag NWs)and the other by interdigital electrode,respectively.The collagen films are regenerated from leather waste and could bring economic benefits to society.The prepared pressure sensors are applied for voice recognition and human motion detection.

Utilization of leather fibrous wastes for the production of reconstituted fibric materials:heavy metal determination and removal

Incomprehension concerning heavy metal containing finished solid leather wastes leads to environmental pollution.Conversion of these solid leather waste into energy and resource efficient products proves to be challenging.However,leather microfibres(LMF)were isolated from these heavy metal containing finished solid leather wastes.These heavy metal contain LMF further processed into metal reduction LMF.The metal reduction LMF were investigated for their heavy metal removal efficiency and toxicity analysis.The Cr(III)and Cr(VI)content of LMF was<1000μg/mL and<800μg/mL,respectively.Toxicity estimation was proved that the LMF had less than 1%.The study attempt to prepare reconstituted fibric materials(RFM)from metal reduction LMF and cellulose nanofibres(CNF).RFM were characterized for their physicochemical and mechanical properties.Hence,the study has proved a novel concept of RFM production which is recyclable,environmental friendly and cost effective.

Research progress on resource utilization of leather solid waste

Leather making is the process of converting raw hides into leather.Amounts of solid waste containing hazardous and high value components are generated during this process.Therefore,the elimination of the potential pollution and resource utilization of leather solid waste are the primary research hotspots.Herein,we comprehensively review the recent advances in the resource utilization of leather solid waste generated from chrome tanning including the utilization of tannery hair waste,untanned solid waste,chrome-containing leather solid waste,tannery sludge and finished leather waste,emphasizing on the general and novel utilization approaches.Finally,the remaining challenges and perspectives were summarized,in order to accelerate the development of resource utilization of leather solid waste.

Research on the composite and functional characteristics of leather fiber mixed with nitrile rubber

The recycling of leather solid waste not only involves resource utilization and environmental protection but also has important significance for the sustainable development of the leather industry.In this paper,the leather waste was crushed into fibers,which were stabilized and mixed with nitrile-butadiene rubber(NBR).The mixture was milled and vulcanized and a composite NBR-SLF(Stabilized Leather Fiber)is prepared for sealing material.The physical and mechanical properties,water resistance,oil resistance and aging resistance of NBR-SLF were tested and analyzed.It is found that the optimized NBR-SLF not only reduces the cost of raw material,but also changes the physical and mechanical performance of NBR.As a sealing material,it satisfies the substitution of NBR in terms of hardness and thermal stability.Especially the anti-aging ability is better than NBR.