Enhanced photocatalytic degradation of nigrosine dye from its aqueous solution using La2Ce2O7 nanoparticles

Abstract

In the present work, removal of nigrosine dye from its aqueous solution via combined photocatalysis and adsorption has been reported using ternary catalyst lanthanum cerate under visible light. The catalyst has been synthesized by citric acid assisted sol-gel method. XRD graph reveals that the average crystallite size of sample is found to be approximate 4.0 nm having cubic fluorite structure. There is 64.45% oxygen. 17.76% lanthanum and 17.79% cerium atoms present in the material, as observed by EDS result. FESEM results shows that obtained particles are in the form of rice grain shape arranged densely in homogeneous manner. TGA curve shows that there is a evaporation of moisture, nitrate and carbon. Two exothermic peaks are observed at about 170°C and 200°C in the DTA curve. The UV-Visible spectrum gives the band gap of lanthanum cerate and it is 3.0 eV. A spectrophotometer has been used to follow the photocatalytic degradation of nigrosine dye at specific intervals of time. The effect of various parameters such as pH, concentration of dye, photocatalyst dosage and light intensity has been studied on the rate of degradation. A tentative mechanism for degradation of nigrosine has been proposed involving superoxide and hydroperoxyl radicals as main oxidizing species.