Microwave bentonite silylation for dye removal: Influence of the solvent

A series of bentonite silylated samples was prepared with aminopropyltrimethoxy silane over a short period of time (5 min), at 50 °C, using microwave irradiation. The influence of polar and non-polar solvents was investigated. The pristine and modified solids were characterized by structural, thermal and morphological techniques. It was demonstrated that the silylation of smectite using microwave irradiation is a very promising method at shorter times and showed higher functionalization degrees for silylation with a non-polar solvent or ethyleneglycol. The amino modified solids were used to remove Reactive Violet 5R, an anionic dye, from aqueous solutions. Key parameters such as pH, contact time and initial dye concentration on dye removal were investigated. The maximum retentions of reactive violet 5R on the silylated samples were 107.4, 59.7 and 31.5 mg g−1 for solids obtained in ethyleneglycol, hexane and toluene, respectively, at pH 2. In all cases, Langmuir isotherm fitted correctly the data and a pseudo second order kinetic defined clearly the kinetic parameters.