Statistical modelling for the Ultrasonic photodegradation of Rhodamine B dye using aqueous based Bi-metal doped TiO2 supported montmorillonite hybrid nanofluid via RSM

In this study, a novel aqueous based 10% w/w copper (Cu)-nickel (Ni) doped titania (TiO2) supported montmorillonite - k 10(MMT- k 10) clay based hybrid nanofluid at various mixing ratios (Cu: Ni) of 100:0, 75:25, 50:50, 25:75, and 0:100 are prepared using hydrothermal process. The photocatalyst activity has been analysed by degrading the Rhodamine B in a photoreactor under a visible-light source. The Diffuse reflectance spectrum results showed a maximum of 19% reduction in the TiO2 band gap energy by the addition of the metals in the ratio of 75:25. Furthermore, the clay addition improved the adsorption surface area and porosity of the photocatalyst. The effect of nanofluid concentration (1 to 2 vol%), ultrasonication time (before photocatalysis -15 to 30 min), reaction time (20 to 50 min) and the distance between reactant and the lamp (4 to 10 cm), on the photocatalytic degradation of dye solution are analysed using response surface methodology (RSM). The fine-tuning of the input parameters shows 97% photocatalytic degradation of the effluent within 60 min of reaction time. Simultaneously, Analysis of variance (ANOVA) study has been performed to understand the significant effect of the input parameters on the variation of response variable. Based on the results, a new quadratic correlation and a possible photocatalytic degradation mechanism are proposed.