Removal of cationic dyes from aqueous solution by adsorption onto hydrophobic/hydrophilic silica aerogel A Physicochemical and engineering aspects

The hydrophobic (surface modified) silica aerogel (MSA) and hydrophilic (hydroxyl-group) silica aerogel (HSA) were prepared by ambient pressure drying method. The larger specific surface area was obtained in MSA (880.47m²g⁻¹) and HSA (628.52m²g⁻¹) compared with common silica aerogel. The ability of removal of Rhodamine B (RhB) and Methylene blue (MB) from aqueous solution was examined. Results showed that the maximum adsorptions of MB were 65.74mg/g, 47.21mg/g for MSA and HSA, respectively. The maximum adsorptions of RhB were 134.25mg/g and 185.61mg/g for MSA and HSA, respectively. Herein, the Langmuir, Freundlich isotherm models were employed to discuss the adsorption behavior. The results indicated that the equilibrium data were perfectly represented by the Langmuir isotherm. At the same time, Pseudo-first-order and pseudo-secondorder models were employed to analyze the kinetics data and the adsorption behavior can be better described by pseudo-second-order model. Silica aerogel as alternative adsorbent can be used for dye removal in wastewater treatment processes in the future environment governance.