Adsorption of Phenol by Super Hydrophobic Phenol- Formaldehyde/Silica Hybrid Aerogel

Phenol-formaldehyde/silica hybrid gel with hydrophobic character, high porosity, and the small pore size mean was prepared via sol-gel polymerization under solvent saturated vapor atmosphere and was dried by ambient drying method. The silica sols were prepared based on Tetraethoxysilane (TEOS) and Methyltrimethoxysilane (MTES) as hydrophilic and hydrophobic precursors, respectively. Phenol-formaldehyde resin was used as organic phase to achieve suitable physical properties. The contact angle of this aerogel was about 147˚ and it is a result of formation of CH3 groups on the pore walls. The results of FESEM and nitrogen adsorption indicated that the structure of this aerogel is highly porous, uniform, and colloid like network. The Phenol-formaldehyde/silica hybrid aerogel was used for removal of phenol from aqueous solution. The study was carried out as functions of contact time, pH and initial phenol concentration. The experiments demonstrated that maximum phenol removal was obtained at neutral pH in unbuffered condition and it takes 40 min to attain equilibrium. Langmuir, Freundlich and Temkin isotherm models were applied to fit adsorption equilibrium data. The best-fitted data was obtained with the Langmuir model and the adsorption capacity was 97.09 mg g−1. Kinetic studies indicated that the adsorption process was described better by pseudosecond- order model.