Development of Biodegradable Agricultural Mulch Films from Wet Blue Leather Waste Processed Under Citric Acid Hydrolysis

Abstract The leather industry faces challenges in sustainably managing chromium-containing solid waste. This study aimed to develop a gelatin-based film from wet blue leather waste, using acid hydrolysis, to apply it as an agricultural mulching. The leather waste was analyzed for chromium and nitrogen content. Gelatin was extracted through citric acid hydrolysis, and polymeric films were produced with glycerol and starch using casting method. These films were characterized by their chemical structure (IR), thermal properties (TG and DTG), morphology (SEM), mechanical properties (elongation and tensile strength), water solubility, and degradability on soil. The leather waste contained 3.75% chromium oxide and 12% nitrogen. Hydrolysis reduced the chromium content in the gelatin by up to 71%. The resulting gelatin successfully enabled the production of films exhibiting elongation between 40.49 and 149.76%, and average tensile strengths ranging from 5.31 to 12.78 N/mm 2 . While none of the tested films fully satisfied all the mechanical performance criteria established by Brazilian and European standards for soil mulching, the results demonstrate significant potential for further development and optimization toward meeting these benchmarks. Degradability tests showed that the films are biodegradable, providing soil integration and agricultural efficiency while minimizing environmental impacts from non-degradable waste. Graphical Abstract