Recovery of nanosized silica and lignin from sugarcane bagasse waste and their engineering in fabrication of composite membrane for water purification.

Environmental benign catalytic process was developed for the valorisation of sugarcane bagasse into functional nanomaterials. Bagasse saccharification was carried out with an acid catalyst (HSO 0.5%, wt/wt) to separate sugars after pre-treatment of biomass with ethanol. Subsequently, a combination of peroxide and base (0.5% HO, wt/wt and 1% NaOH, wt/wt) was stacked to concurrently synthesise SiO (35 nm with 5.65% yield) and lignin (20 nm with 10.15% yield) from bagasse slurry. In the final step, precipitation using catalyst was completed to separate highly pure functional materials in powdered form. Zeta potential (ζ) of the synthesised materials was found to be - 35.6 mV for SiO and - 13.1 mV for lignin. Obtained silica and lignin nanomaterials were used in the fabrication of strong as well as flexible functional membrane for purification of solute particles and gases. The adsorption/desorption curve of the developed functional membrane showed type II isotherm with a H3 hysteresis loop. The observed Brunauer-Emmett-Teller surface area of the membrane was 400.3 m/g. The pore size and pore volume as recorded by Barrett-Joyner-Halenda method was 25.5 nm and 0.624 cm/g, respectively. Hence, the developed simple and sustainable process could be highly suitable for filtration of contaminated water and air purification.