Selective adsorption of organic dyes by porous hydrophilic silica aerogels from aqueous system.

Hydrophilic silica aerogel (HSA) was obtained by sol-gel method and dried at ambient conditions and further studied for the removal of organic dyes in water. Silica aerogel was characterized by its morphology, porous structure, specific surface area and particle size distribution by scanning electron microscopy, Brunauer-Emmett-Teller and pore size distribution. The HSA after calcination had a specific surface area of 888.73 m2/g and an average particle size of 2.6341 nm. Moreover, adsorption properties of the HSA toward organic dyes - adsorption conditions, kinetics data, and equilibrium model - were investigated. The removal rate of cationic dyes (rhodamine B (RhB), methylene blue (MB) and crystal violet (CV)) by HSA was up to 90%, while the removal rate of anionic dye (acid orange 7) was not more than 30%. The maximum adsorptions were: RhB 191.217 mg/g, MB 51.1601 mg/g and CV 24.85915 mg/g, respectively. Based on the adsorption mechanism of HSA for cationic/anionic dyes, the conclusion confirmed the prospect of HSA as effective adsorbent to treat cationic dyes wastewater.