Photocatalytic decolourization of Rhodamine-B dye by visible light active ZIF-8/BiFeO3 composite.

In this work, preparation of ZIF-8 supported BiFeO3 photocatalyst by ultrasound cavitation technique was reported. The synthesized materials were characterized using solid UV absorption spectroscopy, Raman Spectroscopy, and SEM. The catalytic function of synthesized photocatalyst under ultraviolet and visible light was examined for the decolourization of Rhodamine-B (Rh-B) dye. To understand the action of the photocatalyst on Rh-B decolorization, the influence of different operating parameters such as wt% of ZIF-8 in composite, catalyst dosage, initial dye concentration, initial solution pH, and source of light was examined. The obtained results show that 40.7 wt% of ZIF-8/BiFeO3 composite exhibited the highest possible photocatalytic behaviour against decolorization of Rh-B dye. The acidic pH of the solution had shown greater effectiveness in removing Rh-B dye. The tests and study demonstrate that the hybrid ZIF-8/BiFeO3 has a stronger photocatalytic activity for decolorization of the Rh-B dye relative to the ZIF-8 MOF and BiFeO3. The synthesized ZIF-8/BiFeO3 demonstrated outstanding photocatalytic behaviour in the presence of ultraviolet and visible light towards the removal of Rh-B dye from the aqueous media.

Tannery wastewater treatment by cavitation combined with advanced oxidation process (AOP).

Studies on the degradation of organic pollutants (phenolic, tannins etc.,) present in the wastewater released from tannery industry have been carried out in this work. The combined effect of cavitation and magnetic stirring with the advanced oxidation processes (AOPs) has been compared. The different parameters that affect the chemical oxidation process of the tannery wastewater, like pH, ultrasound irradiation time and dosage of hydrogen peroxide (H2O2) were studied. The samples were treated by two different approaches by varying these parameters. In the first approach, wastewater was treated in the presence of cavitation using ultrasound probe sonicator and in the second approach in the presence of magnetic stirring using magnetic stirrer was used. In both the cases, the suspended total organic carbon (TOC) was measured before and after varying the parameters to ensure the destruction of organic pollutants present in the wastewater sample. The optimum conditions obtained with ultrasonic cavitation was further used in hydrodynamic cavitation set-up in order to increase the efficiency. The experimental results show that the combination of cavitation and H2O2gives a higher reduction in suspended TOC values of tannery wastewater than with addition of only hydrogen peroxide (H2O2).

Investigation of TiO2 photocatalyst performance for decolorization in the presence of hydrodynamic cavitation as hybrid AOP.

In this article, an acoustic cavitation engineered novel approach for the synthesis of TiO2, cerium and Fe doped TiO2 nanophotocatalysts is reported. The prepared TiO2, cerium and Fe doped TiO2 nanophotocatalysts were characterized by XRD and TEM analysis to evaluate its structure and morphology. Photo catalytic performance of undoped TiO2 catalyst was investigated for the decolorization of crystal violet dye in aqueous solution at pH of 6.5 in the presence of hydro dynamic cavitation. Effect of catalyst doping with Fe and Ce was also studied for the decolorization of crystal violet dye. The results shows that, 0.8% of Fe-doped TiO2 exhibits maximum photocatalytic activity in the decolorization study of crystal violet dye due to the presence of Fe in the TiO2 and it may acts as a fenton reagent. Kinetic studies have also been reported for the hybrid AOP (HAOP) that followed the pseudo first-order reaction kinetics.