Sodium alginate–silica composite aerogels from rice husk ash for efficient absorption of organic pollutants

Sodium alginate–silica (SAS) composite aerogels with excellent absorption capacity were synthesized from rice husk ash through a sol-gel process and freeze drying. The physical and chemical properties of the SAS aerogels were fully characterized using field emission scanning electron microscopy , N 2 adsorption–desorption isotherms, thermogravimetric analysis , Fourier transform infrared spectroscopy, and other techniques. The silica-based composite aerogel containing 18% sodium alginate (18-SAS) had the largest specific surface area of 205.1 m 2  g −1 , the highest pore volume of 0.953 cm 3  g −1 , and the maximum organic-solvent absorption capacity of 6–14 g g −1 . Such an environmentally friendly, low-cost aerogel material with excellent performance is a promising candidate for organic-pollutant absorption.