Valorization of rice straw for valuable materials: towards a zero-waste recovery process

• Published in: Biomass conversion and biorefinery 2024, Vol.14 (23), p.29901-29910
• Main Authors: Vo, Nhi T., Pham, Co D., Ly, Tuyen B., Dang, Minh D.T., Do, Nga H.N., Le, Phung K.
• Format: Article
• Language: English
• Subjects: Agricultural wastes; Aqueous solutions; Biotechnology; Black liquor; Cellulose; Energy; Greenhouse gases; Hydrolysis; Lignin; Materials recovery; Methylene blue; Original Article; Renewable and Green Energy; Silicon dioxide; Waste management; Water consumption
• ISSN: 2190-6815; 2190-6823
• DOI: 10.1007/s13399-023-04681-0

Rice straw is an abundant agricultural waste, especially in Asian countries, of which a large amount is still open burnt. This leads to the emission of greenhouse gases (CH 4 , N 2 O, etc.) causing huge environmental impacts and is a waste of a cellulose, lignin, and silica source, which are highly valuable compounds. In this work, nanocellulose (CNC) was produced from rice straw using chemical method, together with waste stream utilization. The acid waste from the hydrolysis and the black liquor from cellulose isolation were used to recover a hybrid material of lignin and silica (LS), which was then applied to remove methylene blue from water. CNC was prepared using acid hydrolysis presented as rod-like particles with a crystallinity of 85% and a diameter of 20–30 nm in width and 200–400 nm in length, which was of high quality and suitable for further applications. The LS hybrid performed well in adsorbing methylene blue in aqueous solution, with the trapping capacity of 68 mg/g. Subsequently, a pilot-scale integrated process to produce CNC and LS hybrid was proposed to reduce the chemical and water usage in treating waste stream and move towards the “zero-waste” concept and circular economy principle. The process is a possible solution for facile and feasible large-scale transformation of rice straw into value-added products. Graphical abstract