New Hibiscus Sabdariffa L petals extract based Green synthesis of zinc oxide nanoparticles for photocatalytic degradation of Rhodamine B dye under solar light
Hassan Abbas Alshamsi, Abeer A. Jaffer
Abstract
The current research reports an easy green, cost effective and efficient route for synthesis of Zinc Oxide nanoparticles (ZnO NPs) using the petals extract of Hibiscus Sabdariffa L .Different masses of Zn(NO3)2.6H2O were adopted to produce a series of ZnO NPs samples ;Z1,Z2,Z3 and Z4.The crystalline structure, optical properties, surface topography, morphology, elemental composition ,thermal stability ,surface area and porosity, and chemical composition of ZnO NPs were done through various techniques such as X-ray diffraction(XRD), diffuse reflectance spectroscopy(DRS),atomic force microscopy(AFM) , field emission scanning electron microscopy(FESEM) , energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis -differential scanning calorimetry (TGA-DSC), Brunauer–Emmett–Teller/ Barrett-Joyner-Halenda method( BET/BJH), and Fourier-transform infrared spectroscopy (FTIR) .The results of FTIR indicate the appearance of main bands of zinc oxide. In addition, the XRD results demonstrated the phase purity of ZnO NPs. The SEM analysis indicate that the most ZnO NPs had a spherical and quasi-spherical shapes with mean average size ranging from 58 - 70 nm.AFM shows thickness and roughness increase when the mass of Zn precursor (ZP) was increasing . BET and BJH results indicate that Z4 sample possess the highest surface area (20.82 m2/g) and mean pore diameter (83.09 nm). Thermal analysis of ZnO NPs samples (before annealing) revealed three endothermic peaks around 200 °C, 310 °C and 595 °C. The EDX analysis shows that the synthesized ZnO samples include only zinc and oxygen.DRS confirms a slight optical red shift in the energy gap as the ZP mass is increased. The photocatalytic activity of the ZnO NPs was investigated using aqueous solution of Rhodamine B dye. A remarkable degradation efficiency of 80.13 % was achieved after 300 min sunlight irradiation. Recycling of ZnO NPs (Z4 catalyst) was also investigated with a percentage photodegradation of Rh.B dye (69 %) after 5 successive cycles.