VIJAYALAKSHMI RADHAKRISHNAN
Abstract
Copper oxide nanoparticles are prepared adopting green synthesis route by using Aloe vera plant extract instead of synthetic and polymeric stabilizing agents in mild alkaline aqueous conditions. The synthesised CuO nanoparticles (CuO nps) are characterised by Powder XRD and HR-TEM measurements. Using ...
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Copper oxide nanoparticles are prepared adopting green synthesis route by using Aloe vera plant extract instead of synthetic and polymeric stabilizing agents in mild alkaline aqueous conditions. The synthesised CuO nanoparticles (CuO nps) are characterised by Powder XRD and HR-TEM measurements. Using the as –synthesized CuO nps and reduced graphene oxide (rGO), nanocomposites comprising CuO nps- rGO are prepared by hydrothermal and ultrasonic methods. Nano composites are characterized using Powder XRD, HR-TEM and FE-SEM data. The fabricated CuO nps - rGO nanocomposites are coated onto glassy carbon electrode (GCE) for facile detection and electro oxidation of water polluting dyes such as the Ponceau 4R (P4R) and Alizarin Red (AR) using cyclic voltammetry . Electro oxidation of the dyes occurred at appreciably lower oxidation potentials like 0.45 V and 0.6 V for P4R and AR respectively along with the decoloration of the dyes. The absorbance of the analyte dye solutions are measured at intervals of time of progress of electro oxidations. The overall first order rate coefficient values for dye degradations are found out from absorbance time variance data. The results indicate that CuO nps - rGO nanocomposites decorated GCE acted as an efficient electrode surface for sensing and degradation applications for the chosen dye solutions. P4R azo dye degradation response was found to be better than AR anthroquinon dyes.
Subramanian Kanchana; Radhakrishnan Vijayalakshmi
Abstract
Photocatalysis mediated by metal nanoparticles is emerging as an effective method for removal of hazardous dye pollutants in natural aquatic bodies. Nanoparticles of Cu, Ni and Ag were synthesized by chemical method using PEG and PVP polymers as capping agents. Experimental photocatalyis was carried ...
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Photocatalysis mediated by metal nanoparticles is emerging as an effective method for removal of hazardous dye pollutants in natural aquatic bodies. Nanoparticles of Cu, Ni and Ag were synthesized by chemical method using PEG and PVP polymers as capping agents. Experimental photocatalyis was carried out in a one pot batch reactor using metal nanoparticle catalysts for degradation of crystal violet (CV), bromocresol green (BCG) and methylene blue (MB) in aqueous solution in the presence of NaBH4 reductant independently under solar and UV irradiations at 25oC. Metal nanoparticles caused the removal of BCG and CV in 90-120 min and MB in 30-60 min. Linear relationship between the irradiation time and the absorbance were recorded and the kinetic plots exhibited pseudo-first order kinetic. The trend of dye degradation among the nanoparticles based on the catalytic efficiency (c) and rate coefficient (k) values was Cu>Ag>Ni. Mineralization experiment indicated 94, 91 and 90% of TOC removal ratio (R) respectively for CV, MB and BCG dyes. Nanoparticles stabilized using PEG demonstrated better catalytic efficiency than those with PVP. Solar irradiation showed superior augmenting effect on the nanoparticle catalysts than the UV irradiation. The electron-hole pair mediated reduction mechanism was proposed as a basis for photocatalytic degradation of dyes.