Synthesis and characterization of silica xerogel from corn husk waste as cationic dyes adsorbent

Background: High corn production and consumption in Indonesia have led to massive corn husk waste. To increase the economic value of corn husk waste, innovations have utilized its silica content as an alternative source for the synthesis of multifunctional silica compounds. Methods: In this research, silica xerogel was successfully synthesized from corn husk via the sol-gel method. Its physical properties and capabilities as an adsorbent to remove cationic dyes such as crystal violet and methylene blue in wastewater were investigated for the first time. Results: The as-synthesized silica xerogel possesses an amorphous crystal structure with an average pore diameter of 6.35 nm, a Brunauer, Emmett, and Teller (BET) surface area of 363.72 m (2)/g, and particle size ranging from 80 to 250 μm. The optimum contact times of silica xerogel are 90 minutes for crystal violet and 120 minutes for methylene blue adsorptions. While at the same time, the dye removal efficiencies are as high as 98.539% and 96.184%, respectively. The adsorption of both crystal violet and methylene blue on silica xerogel follows the Langmuir isotherm model and exhibits a high monolayer capacity of 69.44 mg/g and 59.17 mg/g, respectively. Conclusions: These findings suggest the great potential of silica xerogel synthesized from corn husk as a low-cost and effective cationic dye adsorbent.