Green synthesis of nickel nanoparticles using Ocimum sanctum and their application in dye and pollutant adsorption

Nickel nanoparticles as an eco-friendly adsorbent was biosynthesized using Ocimum sanctum leaf extract. The physiochemical properties of green synthesized nickel nanoparticles(Ni Gs) were characterized by UV–Vis spectroscopy(UV–Vis), Fourier Transform Infrared Spectroscopy(FTIR), X-ray diffraction(XRD), Scanning Electron Microscope(SEM) and Transmission Electron Microscope(TEM). Ni Gs were used as adsorbent for the removal of dyes such as crystal violet(CV), eosin Y(EY), orange II(OR) and anionic pollutant nitrate(NO3-), sulfate(SO42-) from aqueous solution. Adsorption capacity of Ni Gs was examined in batch modes at different p H, contact time, Ni G dosage, initial dye and pollutant concentration. The adsorption process was p H dependent and the adsorption capacity increased with increase in contact time and with that of Ni G dosage, whereas the adsorption capacity decreased at higher concentrations of dyes and pollutants. Maximum percentage removal of dyes and pollutants were observed at 40, 20,30, 10 and 10 mg·L-1initial concentration of CV, EY, OR, NO3-and SO42-respectively. The maximum adsorption capacities in Langmuir isotherm were found to be 0.454, 0.615, 0.273, 0.795 and 0.645 mg·g-1at p H 8, 3, 3, 7and 7 for CV, EY, OR, NO3-and SO42-respectively. The higher coef ficients of correlation in Langmuir isotherm suggested monolayer adsorption. The mean energies(E), 2.23, 3.53, 2.50, 5.00 and 3.16 k J·mol-1for CV, EY, OR, NO3-and SO42-respectively, calculated from the Dubinin–Radushkevich isotherm showed physical adsorption of adsorbate onto Ni Gs. Adsorption kinetics data was better fitted to pseudo-second-order kinetics with R2 N 0.870 for all dyes and pollutants. Ni Gs were found to be an effective adsorbent for the removal of dyes and pollutants from aqueous solution and can be applied to treat textile and tannery ef fluents.

Plastic supported platinum modified nickel electrode and its high electrocatalytic activity for sodium borohydride electrooxidation

A novel plastic/multi-walled carbon nanotube（MWNTs）-nickel（Ni）-platinum（Pt） electrode（PMNP） is prepared by chemical-reducing Pt onto the surface of Ni film covered plastic/MWNTs（PM） substrate. The MWNTs are adhered by a piece of commercial double faced adhesive tape on the surface of plastic paper and the Ni film is prepared by a simple electrodeposition method. The morphology and phase structure of the PMNP electrode are characterized by scanning electron microscopy,transmission electron microscope and X-ray diffractometer. The catalytic activity of the PMNP electrode for Na BH4 electrooxidation is investigated by means of cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the plastic paper and exhibits a good stability. MWNTs serve as both conductive material and hydrogen storage material and the Ni film and Pt are employed as electrochemical catalysts. The PMNP electrode exhibits a high electrocatalytic performance and the oxidation current density reaches to 10.76 A/（mg·cm） in 0.1 mol/dm3 Na BH4at0 V,which is much higher than those in the previous reports. The using of waste plastic reduces the discarding of white pollution and consumption of metal resources.