The Fermi level is referred to as the electrochemical potential and plays an important role in the band theory of solids. When metal and semiconductor are in contact, electron migration from photoirradiated semiconductor to the deposited metal occurs at the interface until two Fermi levels equilibrate and enhanced the photocatalytic activity of semiconductor photocatalyst. Ni2+ having more negative reduction potential (−0.25 eV) than the CB of TiO2 imparts negligible co-catalytic activity to TiO2 photoreaction. It also revealed that loading of Au3+ ions displayed higher degradation rate of pyrene than Au photodeposition. Furthermore, when the amount of dissolved Fe+3 and Au3+ ions gradually increases from 0.1 to 2 wt.%, the pyrene photodecomposition rate also become faster.

Abstract:The sorption of diesel, lubricant and castor oils onto different parts (root, stem and leaf) of the dry biomass water hyacinth was studied at the laboratory scale. The parts of the aquapyte water hyacinth (Eichhornia Crassipes) were characterized by physico-chemical methods and the characteristics were used to elucidate the oil sorption process. Hydrophobicity, wettability (capillarity), buoyancy and sorption capacity of oils in the presence/ absence of water were studied to evaluate the suitability of the sorbent for application. In all the three sorbents, the oil sorption capacity increases with the increase of oil film thickness. However of the three parts, the stem has a greater sorption capacity of 9.3, 7.8 and 11.08 g/g for the three oils such as diesel, lubricant and castor oils respectively, even though the root of water hyacinth showed a higher hydrophobicity and surface area. These sorption capacities are comparable with widely used commercial oil sorbent such as nonwoven polypropylene which has a sorption capacity in the range of 10-16 g/g.