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The degradation of disperse V-26 in solution using UV; UV/H2O2, UV/H2O2/TiO2and UV/H2O2/ZnO were investigated. The impacts of various key parameters i.e. initial pH, concentration of hydrogen peroxide (H2O2) dose and the dye concentration effect on degradation were studied. The maximum degradation of 93 % was optimized using UV/H2O2/TiO2at pH 3 in 60min. Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GCMS) were applied to check the products obtained after complete degradation. The removal of peaks of certain groups present in dye molecule assured the maximum degradation of dispersive V-26. In biological treatment, cytotoxicity reduction and Ames test were used to check the toxicity level of products. Certain water parameters i.e. dissolved oxygen (DO), chemical oxygen demand (COD) and biological oxygen demand (BOD) were also performed to ensure the maximum degradation of DV-26. DO was increased up to 82 %. The COD and BOD were reduced considerably owing to the treatment of disperse dye Violet 26 at optimum settings of process variables. The degradation of disperse dye V-26 with UV/H2O2/ZnO was 90.1 % which increased up to 93 % with the alternative photo-catalyst UV/H2O2/TiO2.

The present study describes the potential use of 3D MnO2nanofibrous mesh as photocatalyst for removal of organic dye. The MnO2nanofibrous mesh has synthesized through facile, one-pot and cost-effective hydrothermal approach without using any template or other structure directing compounds. 3D MnO2patterns clearly depict the well-dispersed nanofibers having diameter in the range of 10–25nm, and several microns in length; the unique mesh morphology offers a large surface area to promote enhanced photocatalytic activity, and also provided a macro porous network that supported efficient oxidation. Moreover, the strong electronic cloud and high aspect ratio (HAR) MnO2nanofibers facilitated the fast oxidation of dyes molecule in a very short period of time. The designed nanostructured material was found to possess heterogeneous photocatalytic potential against the oxidative degradation of Crystal Violet (CV) dye taken as model pollutant. The photocatalytic performance of these materials was evaluated under ultra-violet as well as visible light. Best photocatalytic performance was achieved under visible light with almost complete degradation (97%) exhibited within 90min of irradiation time. Furthermore, the degradation efficiency of prepared photocatalyst was determined in presence and absence of initiator, hydrogen peroxide, and under different pH conditions. Finally, this technique can be easily scaled-up for removal of various polycyclic organic wastes that might be of potential industrial and environmental interests.

A facile green synthesis route was employed for the fabrication of Ag-Zn doped TiO2nano-catalyst and utilized for the remediation of dyes. Nicotiana tabacumleaves extract was used to prepare the Ag-Zn doped TiO2nano-catalyst by utilizing TiO2as precursor and AgNO3, ZnNO3as doping agents. A strong UV-Vis spectra peak confirmed the Ag-Zn doped TiO2formation. Furior transformed infrared spectroscopy analysis revealed the role of phenolics in the Nicotiana tabacumleaves extract for the formation of Ag-Zn-doped TiO2nano-catalyst. Moreover, Ag-Zn doped TiO2nano-catalyst formation was confirmed by X-ray diffraction analysis, which reveals the cubic and tetragonal geometries with average size of 5.66 nm. The scanning electron microscopy analysis also confirmed the poly-morphological structure of prepared Ag-Zn doped TiO2nano-catalyst. The nano-catalyst was used for the remediation of dyes and conditions were optimized for maximum removal of dyes using NaBH4reducing agent. The catalytic activity results revealed that Ag-Zn doped TiO2showed promising features versus individual counterparts, which is correlated with reduced bandgap of doped nano-catalyst. The Nicotiana tabacumleaves extract efficiently stabilized Ag-Zn doped TiO2nano-catalyst that exhibited remarkable catalytic activity and have potential to treat the dyes in wastewater.