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Pharmaceutical residues have been increasingly detected in the aquatic environment and are considered important contaminants of emerging concern. This study examines the photo assisted electrochemical degradation of the Hydrochlorothiazide by using CdSe quantum dots decorated SnO2 nanotubes. The characteristic devices such as Scanning electron microscopy, X-ray diffraction, UV-vis diffuse reflectance Transmission electron Microscopy were used to analyze information structure of CdSe QDs/SnO2 nanotubes. All the experiments were perform with influence of the current density (10-60mAcm-2) and sodium chloride (0.02-0.10molL-1) in the supporting electrolyte composition was analyzed. The results showed that the Hydrochlorothiazide and TOC removal was achieved in the current density range used. As expected, the degradation kinetics presented a pseudo first order behavior. Comparison of the efficiencies of the photocatalytic, electrochemical (EC) and photo-assisted electrochemical (PAEC) techniques verified that the combined process showed a synergism for HCT and TOC removal.

Pure and zinc-doped CdO NPs (Zn-CdO NPs) were synthesized through a facile co-precipitation method. The structural, morphology, chemical composition, optical and antibacterial activity of the NPs were studied with respect to pure and Zn-doped CdO concentration (0–7.5 mol.%). Scanning electron microscope (SEM) images reveal that pure and Zn-doped CdO NPs were in the nano-scale regime with different crystalline morphology. The energy dispersive X-ray spectroscopy (EDS) spectrum predicts the presence of Cadmium (Cd), Zinc (Zn) and Oxygen (O) in the prepared samples. Optical studies divulge that Zn2+ doping CdO decreases the band gap energy (Eg) (3.36–3.02 eV) with an increase in Zn2+ doping concentration. Optical absorption spectrum of CdO red-shifted as the Zn concentration varied from 2.5 mol.% to 7.5 mol.%. PL spectra displayed a strong UV emission peak at 380 nm. Enhanced Visible emission at 430 and 522 nm with Zn2+ doping interprets the defect density in CdO by occupying Cd2+ vacancies with Zn2+ ions. Photocatalytic studies revealed that 7.5% Zn-doped CdO NPs show maximum degradation for atrazine (ATZ) as herbicide pollution under UV irradiation. Antibacterial studies against (Gram positive) and (Gram negative) bacteria's authenticate that Zn2+ doped CdO nanostructures exhibit excellent antibacterial activity against all bacteria's with an increase in doping concentration.

Magnetic graphene oxide (MGO) nanocomposites have been synthesized by the co-precipitation route. The surface structure of MGO nanocomposites were analyzed by XRD, TEM, SEM, VSM and nitrogen adsorption-desorption instrumental technique. Response surface methodology was used to optimize the removal of methadone by MGO nanocomposites in aqueous solution. Experiments were conducted based on Box-Behnken design (BBD). The influence of three parameters on the removal of methadone was examined using the response surface methodological approach. The significance of independent variables and their interactions were tested by analysis of variance (ANOVA). The optimum pH, adsorbent dose and temperature were found to be 6.2, 0.0098g and 295.7K, respectively. Under these conditions, removal efficiency of methadone was found to be 87.20mg/g.

Graphene quantum dots have been synthesized using the microwave-assisted hydrothermal route. The surface textural and morphological structure of synthesized adsorbent i.e. graphene quantum dots was analyzed using various analytical techniques such as X-ray diffraction, Transmission electron Microscopy, Atomic Force Microscopy and N2 adsorption-desorption instrumental techniques. The application of graphene quantum dots as an adsorbent for the removal of noxious pesticide compound i.e. oxamyl from aqueous solutions was well investigated and elucidated. The impact of several effective parameters such as effect of agitation speed, pH, adsorbent dose, contact time, temperature and initial concentration on sorption efficiency was studied and optimized using batch adsorption experiments. The optimized pH for maximum oxamyl adsorption was found to be 8.0 and for the maximum adsorption rates the adsorbent dose of 0.6g was found to be optimum to carry out the adsorption with in less than 25min of contact time. From the results obtained, it is clear that for all contact times, an increase in oxamyl concentration resulted in increase in the percent oxamyl removal. The adsorption equilibrium and kinetic data were well fitted and found to be in good agreement with the Langmuir isotherm and pseudo-second-order kinetic model.

In this study, the photocatalytic degradation of Strychnine was investigated by ZnS quantum dots and doped with silver in UV systems. ZnS and Ag-ZnS quantum dots were synthesized by chemical method and characterized by powder X-ray diffraction, transmission electron microscopy, UV-vis spectra and photoluminescence. The charge transfer process on the semicon-ductor/electrolyte interface was investigated via electrochemical impedance spectroscopy (EIS) and time-resolved photoluminescence. The average diameters of ZnS and Ag doped ZnS QDs were 3.0-5.0nm and 3.0-5.3nm, respectively. The band gap of ZnS and Ag-ZnS QDs was computed as 3.47 and 3.1eV, respectively. The surface area values of ZnS and Ag-ZnS QDs have been found as 78.25 and 89.54m2/g, respectively. The influences of key operating parameters such as initial pH, catalyst dosage, UV radiation intensity, reaction time as well as the effect of initial Strychnine concentration on mineralization extents were studied. The results of the study showed that the maximum removal efficiency of Strychnine had been achieved by un-doped and Ag-doped ZnS QDs at radiation intensity of 100W/m2, at time of 60min, pH of 3 and initial Strychnine concentration of 20mg/ml. Also the observations clearly showed that the photocatalysis process with Ag doped ZnS QDs are more effective than un-doped ZnS QDs.

The studies of kinetics and thermodynamics of adsorption of Ethidium bromide in aqueous solutions on single-walled carbon nanotube (SWCNT) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces were by UV–Vis spectroscopy. The adsorption kinetics for SWCNT-COOH and SWCNTs were well described by a intra-particle diffusion model, while Langmuir, Freundlich, Harkins–Jura, and Halsey isotherms described the adsorption isotherms, and the adsorption thermodynamic parameters of equilibrium constant ( K 0 ), standard free energy (Δ G 0 ), standard enthalpy (Δ H 0 ), and standard entropy changes (Δ S 0 ) were measured. The maximum surface coverage for SWCNTs is 36.10% and for SWCNT-COOH is 38.42%. The values of Δ H 0 and Δ G 0 suggested that the adsorption of EtBr on SWCNT-COOH and SWCNTs was endothermic and spontaneous. The adsorption of EtBr on SWCNT-COOH is more than SWCNTs surfaces.