Intensification of Rhodamine-B dye removal using hydrodynamic cavitation coupled with hydrogel adsorption

Abstract

In this work, decolorization of rhodamine-B (Rh-B) dye was investigated by using a hybrid treatment technique involving hydrodynamic cavitation (HC) and hydrogel adsorption. Halloysite nanoclay embedded poly-acrylic acid (PAA) nanocomposite hydrogel was prepared by using the ultrasound polymerization technique. Halloysite nanoclay and the synthesized hydrogels were further characterized by using TEM analysis were carried out in order to confirm the structure and morphology of the respective materials. Decolorization of Rh-B dye was carried out by HC followed by adsorption of dye molecules on the hydrogel nanocomposite. Effect of different operating parameters such as inlet pressure to the cavitation device, effect of clay content in the hydrogel, effect of hydrogel loading in adsorption column, the effect of pH on Rh-B dye removal was tested. The individual effects of HC and hydrogel adsorption on Rh-B dye removal were also studied. It was found that the HC assisted hydrogel nanocomposite adsorption shows the decolorization of 65% at the optimized operating conditions such as, pH 7.62, 0.5 g clay loaded nanocomposite hydrogel, and 25 g of hydrogels loading in adsorption column. Addition of H2O2 into the hybrid system further enhances the decolourization of Rh-B dye to 72.85% with 45% of total organic carbon removal at the optimum conditions.