Effect of low pressure alkaline delignification process on the production of nanocrystalline cellulose from rice husk

Large scale production of nanocrystalline cellulose (NCC) remains a challenging task despite significant progress being made in the understanding of the production chemistry at a bench-scale. In this paper an attempt is made in looking into the scale-up option of a wellestablished chemistry to identify the bottlenecks involved in the scaleup process. For the production of NCC at a moderate volume of 2.5 liters using chemical modification steps (delignification, bleaching and hydrolysis), the estimated yield of < 30% has been reported in literature. This work found that inefficiencies in the delignification process prevented higher product yield. The low pressure alkaline delignification (LPAD) stage, which is used for the first time here, was found to enhance the pulping efficiency and subsequently increases the yield (>95%) of the NCC without compromising the quality of the end products. Analyses by FTIR, XRD, EDX, DLS, SEM, AFM, and TEM reveal that the product quality falls in the range of physical dimension as reported previously. The study suggests that a critical analysis of the reaction pathways from an engineering stand-point is essential for scaling-up of NCC production processes. The LPAD of RH using jacketed reactor enables the production of high quality pulp which might be a good approach for industrial production of NCC.