Afrinal Firmanda, Farah Fahma, Khaswar Syamsu, Rini Purnawati, Fery Haidir Irawan, Abdul Munif, Lisman Suryanegara, Melbi Mahardika, Ika Atsari Dewi, Colleen MacMillan
Transforming oil palm empty fruit bunches (OPEFB) waste into value-added cellulose as a reinforcement agent for eco-friendly slow-release fertilizer (SRF) composites is a strategy to achieve clean and sustainable production. OPEFB cellulose was isolated by alkalization (10 % w/v NaOH) for 1 h and bleaching (30 % v/v H2O2) for 1.5 h. The treatment increased the cellulose content to 80.88 %, reduced the non-cellulosic component, and improved the fiber crystallinity to 58.40 %. The hydrogel composite was cross-linked by blending urea in an OPEFB cellulose fiber (w/w) (0 %, 0.5 %, and 1 %) and sodium alginate (3 % w/w). Then, the wet beads were freeze-dried to fabricate SRF composites. Each material was evenly dispersed in the matrix, had a porous structure, and could bind total nitrogen up to 20.0 %, confirmed by the Kjeldahl method. Adding cellulose increased crystallinity (significant at 1 % w/w cellulose), decreased bulky density (significant at 0.5 % and 1 % w/w cellulose), increased swelling capacity (significant at 0.5 % w/w cellulose), and water-retention capacity. Reinforced composite with 0.5 % (w/w) cellulose released nitrogen into the soil (Fickian diffusion) following the Higuchi model (R2 = 0.957) with K = 0.0394 and equilibrium at around t1/2 = 1.8 h. Changing SRF composite properties are likely related to the porous structure loaded with urea crystals. © 2024 Elsevier B.V.
Department of Agroindustrial Technology, Faculty of Agricultural Engineering and Technology, IPB University, Indonesia; Department of Chemical Engineering, Faculty of Engineering, University of Indonesia, Depok, Indonesia; Department of Plant Protection, Faculty of Agriculture, IPB University, Indonesia; Research Center for Biomass and Bioproduct, National Research and Innovation Agency, Bogor, Indonesia; Department of Agroindustrial Technology, Faculty of Agricultural Technology, Universitas Brawijaya, Indonesia; Commonwealth Scientific and Industrial Research Organisation (CSIRO), Agriculture and Food, Canberra, 2601, ACT, Australia