Optimization of purity and yield of amorphous bio‐silica nanoparticles synthesized from bamboo leaves

The fallen yellowish bamboo leaves around bamboo crops are always overlooked even though they contain high silica in their ash. Bamboo leaf valorization consequently has the potential to be a green process for synthesizing amorphous silica. Unfortunately, the optimum process parameters have not been widely disclosed. Hence, this study intends to optimize the synthesis of amorphous bio‐silica nanoparticles from bamboo leaves using Box–Behnken design (BBD). Bamboo leaves were initially washed with HCl, followed by combustion at 700°C, and then ash washing, extraction of silica with NaOH (sol–gel method), gelation, and drying. According to the results, optimum conditions occur under no acid washing of leaves, solvent‐to‐feed ratio = 5 mL/g, and extraction duration = 1.5 h. The optimum conditions give the highest purity (94.1 wt.%) and yield (42.33%) as well as the highest surface area (328.61 m 2 /g), smallest pore diameter (8.69 nm), and largest pore volume (0.71 cc/g) of bio‐silica nanoparticles. Furthermore, bio‐silica nanoparticles are amorphous, spherical‐shaped aggregates, and have a white powdered colour.