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ABSTRACTHere, we report the stable and surfactant-free CuxAg1−xS composites as nanorod clusters was fabricated by a simple hydrothermal method for the degradation of pesticides including malathion (MLT), monocrotophos (MCP), and chlorpyrifos (CPS) under ultraviolet (UV) light. The degradation of MLT, MCP, and CPS using Cu0.5Ag0.5S were up to 97% after 1 h of UV irradiation. The Cu0.5Ag0.5S nanorods displayed enhanced photocatalytic activity and the rate of degradation was higher than that of pure CuS and Ag2S due to an efficient electron transfer process. The stability and reusability assays indicated that the Cu0.5Ag0.5S retained more than 90% of activity after five cycles of use. The photocatalytic mechanism was explored from the obtained results of enhanced photocatalytic activity of CuxAg1−xS nanorod clusters.

Here, we report the stable and surfactant-free CuxAg1-xS composites as nanorod clusters was fabricated by a simple hydrothermal method for the degradation of pesticides including malathion (MLT), monocrotophos (MCP), and chlorpyrifos (CPS) under ultraviolet (UV) light. The degradation of MLT, MCP, and CPS using Cu0.5Ag0.5S were up to 97% after 1?h of UV irradiation. The Cu0.5Ag0.5S nanorods displayed enhanced photocatalytic activity and the rate of degradation was higher than that of pure CuS and Ag2S due to an efficient electron transfer process. The stability and reusability assays indicated that the Cu0.5Ag0.5S retained more than 90% of activity after five cycles of use. The photocatalytic mechanism was explored from the obtained results of enhanced photocatalytic activity of CuxAg1-xS nanorod clusters.

Zero-valent iron nanoparticles (ZVIN) are widely synthesized by several methods in the last decades because it offers indisputable advantages to almost every area of expertise, heavy metal ions removal, environmental remediation including for the wastewater treatment. Herein, we report for the first time, the green and eco-friendly synthesis of phytogenic ZVIN using reproducible Catharanthus roseus(CR) flower extract for the removal of heavy metal ions including Cr(VI) by adsorption isotherms. The synthesized stable ZVIN were characterized by UV-visible absorption spectroscopy (UV-vis), Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The FT-IR analysis reveals that the polyphenolic compounds that are present in the CR flower extract may be responsible for the reduction and stabilization of the ZVIN. The XRD and SEM-EDX analyses confirmed the phase, composition of elements and morphology of the ZVIN. The synthesized low-cost and non-toxic ZVIN used for the adsorption removal of Cr(VI) from contaminated water; and the Langmuir and Freundlich adsorption isotherms are used to study the adsorption process by the experimental equilibrium adsorption data. The maximum removal of Cr(VI) (98.28%) was observed using optimal conditions of 1.6 g/L of ZVIN concentration, 10 ppm of Cr(VI) concentration, and pH = 4.3 of the initial solution. The adsorption removal of Cr(VI) using the synthesized ZVIN as follows pseudo-second-order kinetic equation with a corresponding correlation coefficient of (R2= 0.99).

We report the simple synthesis of zinc sulfide nanoparticles (ZnS NPs) by a co-precipitation method using Schiff base, (2-[(4-methoxy-phenylimino)-methyl]-4-nitrophenol) as a capping agent. The formation of ZnS NPs and their optical, structural, thermal properties and morphologies were studied by means of UV–vis DRS, PL, FTIR, XRD, SEM, TEM, and TGA. The optical properties and quantum confinement effect of the products were confirmed by means of spectroscopic measurements. We have accessed the photocatalytic ability of the prepared ZnS and Schiff base capped ZnS NPs in the degradation of chlorpyrifos under UV light irradiation for the prevention of environmental pollution. The prepared ZnS NPs exhibited a selective probe detection of Fe3+, Cr2+and Cd2+ions by fluorometrically and the emission band which disappears in the presence of increasing concentrations of Fe3+, Cr2+and Cd2+ions. Our work suggested that the synthesized Schiff base capped ZnS NPs could be a potential selective photocatalyst for the degradation of toxic pollutants and a selective probe sensor for the detection of heavy metal ions.

Among the admired photocatalysts, metal sulphide-based semiconductors are most prominent photocatalysts for the degradation or decomposition of dyes in wastewater industries with low cost, environment-friendly and sustainable treatment technologies for the environmental protection. In recent years, the environmental pollution poses a serious threat to the environment and public health. To overcome the environmental pollution, doped and heterojunction based semiconductor metal sulfide nanostructures (MSNSs) are developed as photocatalysts for the purpose of photocatalytic degradation or removal of large organic dyes in an eco-friendly and sustainable fashion. This comprehensive review starts with a brief overview on dyes as pollutants, dyes classification, dyes decolorization or degradation strategies and focuses on the mechanisms involved in comparatively well understood MSNSs photocatalysts such as ZnS, CdS, CuS, Ag2S, Bi2S3, CoS, FeS, and PbS etc. It particularly discusses the recent advancements to enhance photocatalytic degradation of toxic dyes by using various MSNSs to make it a flexible and cost-effective commercial dye treatment technology. In addition, we have focused on the treatment of organic dyes using different types of MSNSs by photocatalysis and the effects of various parameters such as dopants, heterojunctions, band gap, size, light intensity, surface area, reaction time, and degradation efficiency, etc., are highlighted.

CdS nanoparticles (NPs) are synthesized by sonochemical method using tryptophan as a capping agent. The synthesis process is of one step, using biocompatible capping agent, which is nontoxic. The synthesized NPs are characterized by UV–Vis absorption, fluorescence, FTIR, XRD, TGA, DLS, SEM and TEM. The size of NPs is below 10 nm, as observed from XRD and TEM characterizations. Photocatalytic degradation of methyl orange (MO) dye by the CdS NPs as photocatalysts under sunlight irradiation has been studied. The kinetics of catalysis of synthesized CdS NPs with MO dye follows pseudo-first-order kinetics with reasonable apparent rate constants. A variation of dielectric constant as a function of frequencies of an alternating electric field has been observed with the prepared tryptophan-capped CdS NPs deposited at different concentrations. The electric conductivity of CdS NPs is found to increases with the concentration of tryptophan.

Here, we report the synthesis, characterization and catalytic evaluation of palladium nanoparticles (PdNPs) using xanthan gum, acting as both reducing and stabilizing agent without using any synthetic reagent. The uniqueness of our method lies in its fast synthesis rates using hydrothermal method in autoclave at a pressure of 15 psi and at 120 °C temperature by 10 min time. The formation and size of the PdNPs were characterized by UV–visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The catalytic activity of PdNPs was evaluated on the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride using spectrophotometry.

Stable silver nanoparticles were synthesized using chitosan acting as both reducing and stabilizing agent without using any toxic chemicals. This reaction was carried out in an autoclave at a pressure of 15 psi and 120 °C temperature by varying the time. The influence of different parameters such as time, change of concentration of silver nitrate and concentration of chitosan on the formation of silver nanoparticles were studied. The synthesized silver nanoparticles were characterized by UV–visible spectroscopy, Fourier transform infrared, X-ray diffraction and transmission electron microscopy. The results of catalytic reduction of 4-nitrophenol by sodium borohydride in the presence of green synthesized silver nanoparticles were presented. The antimicrobial activity of silver nanoparticles was tested against Escherichia coliand Micrococcus luteusand was found to be possessing inhibiting property.

Nowadays, the development of metal-metal sulfide interface semiconductors using green approach is best material for the photocatalytic and biological applications. Here, we provided for the first time, an environmentally friendly route to fabricate bovine serum albumin (BSA) assisted Ag@Bi2S3composites through a metal-metal sulphide interface via a simple hydrothermal method for the evaluation of photochemical and biological applications. The synthesized composites were characterized by UV–vis DRS, PL, XRD, TEM, and N2adsorption-desorption isotherms. The UV–vis DRS and PL spectra show that the obtained nano-sized Ag@Bi2S3composite displays enhanced visible-light absorption and a decreased fluorescence emission compared to that of Bi2S3nanorods (NRs). The photocatalytic performances of the synthesized composites were evaluated by the degradation of the single (RhB and MB) and mixed dye (RhB+MB) under sunlight irradiation. The results indicated that the Ag@Bi2S3composite exhibits superior photocatalytic activity (98.38%) than that of individual Ag NPs and Bi2S3NRs due to the synergistic effect of Ag and Bi2S3nanophases in the Ag@Bi2S3composite, which results in an effective charge separation, fast electron transfer from Ag to Bi2S3, and a low recombination of photo-induced electron-hole pairs. The Ag@Bi2S3composite also has good recycling stability up to 5 cycles and its mechanism also investigated. The evaluation of reactive species during the photocatalytic reaction was also carried out. Further, the effects of Bi2S3and Ag NPs on the antimicrobial and antioxidant activity of the resultant Ag@Bi2S3composite were also systematically investigated.

Herein, we report low-cost and stable CuO NPs from the Cu(II)-Schiff base complexes (Cu(II)-L1; Cu(II)-(3-((E)-(6-(trifluoromethoxy)benzo[d]thiazol-2-ylimino)methyl)benzene-1,2-diol, Cu(II)-L2; Cu(II)-(2-((E)-(6-(trifluoromethoxy)benzo[d]thiazol-2-ylimino)methyl)-5-methoxyphenol, and Cu(II)-L3; Cu(II)-(2-((E)-(6-(trifluoromethoxy)benzo[d]thiazol-2-ylimino)methyl)-4-bromophenol) via thermal decomposition method using an electric muffle furnace at 650 °C for 2 h. CuO NPs were characterized by XRD, TEM, UV–vis DRS, PL, and FTIR to investigate the phase, structure, morphological, and optical properties. It was found that the CuO NPs has a monoclinic phase with approximately 15–25 nm size in a spherical shape. The prepared CuO NPs exhibited more than 99% catalytic conversion in the reduction of 4-NP using NaBH4in 12 min of reaction time. The evaluation of pseudo-first-order rate constants in the reduction of 4-NP was also investigated. Moreover, CuO NPs can be reused for 5 cycles without significant loss of catalytic activity. In addition, CuO NPs were found as antioxidant and antimicrobial agents, these are evaluated by DPPH scavenging and paper disc methods, respectively.