DOI: 10.17632/bhv9srhswm.1
title: “Comparative Investigation on Synthesis, Characterisation, Photocatalytic decolouration of Crystal Violet dye by TiO2 and ZnO Metallic Nanoparticles under Ultraviolet, Solar and Infrared radiations”

description: The current research focuses on the synthesis, characterization of metal nanoparticles (TiO2, ZnO), optimization of nanoparticles at different pH, concentration, time, rpm, and decolorization of crystal violet dye by use of TiO2 and ZnO under three different Radiation (UV, solar, infrared). The effect of acidity and alkalinity function on photocatalytic degradation of crystal violet dye with pH ranges of 3, 6, 9, 12 and experimental conditions (10mg ZnO and TiO2 catalyst, for 2, 4, 6, 8, 10mg/L dye concentration) was investigated. The most decoloration was obtained at pH 9 for all dye concentrations, with the most decoloration at 2mg/L dye concentration. pH 12 experiment was also carried out, not taking it to account as the loss of color due to the addition of NaOH. The initial dye concentration was also referred during pH optimization by selecting the concentration range of 2, 4, 6, 8, 10mg/L where degradation decreased with increasing concentration. The effective amount of ZnO catalyst for crystal violet dye was determined at different catalyst and dye concentration from 5mg - 30mg. By increasing the ZnO catalyst concentration initially from 5mg-20mg there was increase in the dye decolouration whereas for TiO2 Nano catalyst By increasing the catalyst concentration initially from 5mg-10mg there was increase in the dye decolouration further analysis decrease in the decolouration was observed.  The equilibrium point for ZnO catalyst was 150 minutes and that of TiO2 catalyst was 120 minutes at 120 optimized rpm. The highest decoloration was seen in UV > SUNLIGHT > IR. 2ppm dye was removed completely in 2hrs with 10mg dose of TiO2 nanoparticle under UV light, whereas removal under solar irradiation was 60% and removal under infrared radiation was 17%. Under UV light, 4ppm dye was eliminated 100% in 3hrs with 10mg dose of TiO2 nanoparticle, whereas removal under solar light was 61% and removal under infrared light was 26%. The dye decoloration of 6, 8 and 10ppm was 96%, 95%, and 93% in 3hrs with 10mg catalytic loading of TiO2 nanoparticle under UV light measured at OD 690nm. Whereas under UV light, 2ppm dye was eliminated 100% in 3hrs with 20mg catalytic loading of ZnO nanoparticle, removal under sun irradiation was 58% and removal under infrared radiation was 26%. 4ppm dye was eliminated 100% in 3hrs with 20mg catalytic loading of ZnO nanoparticle under UV light, while removal under solar irradiation was 52% and removal under infrared radiation was 23%. The dye elimination of 6, 8, and 10ppm was 94%, 89% and 84% in 3hrs with 20mg dose of ZnO nanoparticle under UV radiation. When TiO2 and ZnO Nano catalysts for crystal violet dye are compared, TiO2 Nano catalyst is more efficient than ZnO. The findings of this pilot study can be used to establish benchmark, practical, and decisive recommendations for Crystal Violet dye decoloration using synthetic metallic nanoparticles at regional, national and global scales.