Functionalized bentonites for dye adsorption: Depollution and production of new pigments

Abstract

In this work, functionalized bentonites were obtained by silylation under microwave heating at 50 °C for 5 min and then subsequently reacted with glutaraldehyde. Violet 5R, an organic dye, was adsorbed onto the hybrid bentonites for environmental applications and for producing new pigments. Infrared spectroscopy was used to monitor the grafting process, while the degree of functionalization was calculated by using CHN elemental analysis. X-ray diffraction and transmission electron microscopy (TEM) were carried out to evaluate the changes in the basal spacings. Zeta potential measurements were indicated that their surfaces were positively charged below pH 3. The influences of the pH, dosage of adsorbents, contact time and initial concentration of the organic dye were thoroughly investigated. Studies on the stability/photodegradation of the dye amino-imino bentonite composites were performed by using spectrophotocolorimetric analysis. Aging tests revealed the high stabilities of the prepared pigments even after 450 h of light exposure. The results suggested that the organobentonites are good adsorbents for Violet 5R dye and their resulted composites behaved as stable pigments.