Sugarcane Bagasse Fibers Derivatives and Their Application in Chitosan-Based Composite Films for NPK Fertilizer Release

Encapsulation and release of NPK fertilizer by composite films were systematically demonstrated by casting dispersions of chitosan (CS) and sugarcane bagasse (SCB) derivatives (holocellulose (HC), cellulignin (CL), and cellulose (CEL)) fibers under varied CS-to-NPK and CS-to-SCB derivatives mass ratios. SCB derivatives were obtained from sugarcane bagasse as agricultural waste by following the alkali dissolution (4% NaOH, 70 °C for 5 min), sodium chlorite delignification (1.4% NaClO2, pH 3.5, 70 °C, 5 h), or from a combination of both. Nutrientadsorption capacity can be tunable by the chemical composition of SCB derivatives, i.e., fibers with noncellulosics exhibited higher adsorption capacities while the absence of noncellulosics lessened their adsorption capacity. Oven-drying (60 °C, 5 h) of optimal 1:0.5 CS/NPK film-forming solution produced highly uniform films with shape with 0.31 ± 0.02 mm thickness while increasing fiber content in the solution to 25 or 50% prevents films retraction effect. The release of highly water-soluble NPK fertilizer from these composite films was lower with hemicelluloses (52-82%) or lignin (55-92%) contents in SCB fiber than in noncellulosics absence (71-100%), thus could be tuned by varying the chemical composition SCB derivative, followed by a quasi-Fickian diffusion mechanism in water.