Synthesis of Fe3O4/CdS-ZnS nanostructure and its application for photocatalytic degradation of chlorpyrifos pesticide and brilliant green dye from aqueous solutions.

Chlorpyrifos (CP) is an organophosphorus pesticide used to control pests in agriculture. Brilliant green (BG) is a cationic dye widely used in textile and dyeing industry. However, the presence of pollutants in the aquatic environment has harmful effects on the environment and humans. Photocatalytic degradation can be appropriate method for water purification. Therefore, the Fe3O4/CdS-ZnS magnetic nanocomposite was synthesized and characterized by Brunauer-Emmett-Teller (BET) surface area analysis, Energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), UV-Vis-diffuse reflectance spectroscopy (DRS), and field emission scanning electron microscopy (FESEM) analyses and was used to degrade pollutants such as chlorpyrifos pesticide and brilliant green dye under visible light with source 300 W. Parameters that may be effective on photocatalytic degradation include pH, photocatalyst amount, contaminant concentration, photocatalyst and contaminant contact temperature and duration, light intensity as well as distance of light source from the reaction vessel. In the present study, the parameters that have the most influence on the degradation process were experimentally optimized, including pH, photocatalyst amount, photocatalyst reuse, and initial concentration. The study of the photocatalytic degradation rate of chlorpyrifos and brilliant green in optimal conditions (pH = 7, the concentration of pollutants = 10 ppm, volume of pollutants = 5 mL, and photocatalyst amounts for CP and BG were 0.0100 and 0.0015 g respectively) was obtained by Langmuir-Hinshelwood model. According to this model, the kapp value for CP and BG were respectively 0.0315 and 0.0119 min-1 respectively. It has been concluded that the composition of CdS and ZnS caused inhibition of the recombination of photogenerated charge carriers, leading to high catalytic efficiency. Based on the results, the synthesized nanocatalyst showed that it has the ability to photocatalytic degradation of chlorpyrifos and brilliant green in aqueous solutions.

A microextraction procedure based on a task-specific ionic liquid for the separation and preconcentration of lead ions from red lipstick and pine leaves.

First, the extraction and preconcentration of ultratrace amounts of lead(II) ions was performed using microliter volumes of a task-specific ionic liquid. The remarkable properties of ionic liquids were added to the advantages of microextraction procedure. The ionic liquid used was trioctylmethylammonium thiosalicylate, which formed a lead thiolate complex due to the chelating effect of the ortho-positioned carboxylate relative to thiol functionality. So, trioctylmethylammonium thiosalicylate played the roles of both chelating agent and extraction solvent simultaneously. Hence, there is no need to use a ligand. The main parameters affecting the efficiency of the method were investigated and optimized. Under optimized conditions, this approach showed a linear range of 2.0-24.0 ng/mL with a detection limit of 0.0010 ng/mL. The proposed method was applied to the extraction and preconcentration of lead from red lipstick and pine leaves samples prior to electrothermal atomic absorption spectroscopic determination.

Application of a thiourea-containing task-specific ionic liquid for the solid-phase extraction cleanup of lead ions from red lipstick, pine leaves, and water samples.

Here, task-specific ionic liquid solid-phase extraction is proposed for the first time. In this approach, a thiourea-functionalized ionic liquid is immobilized on the solid sorbent, multiwalled carbon nanotubes. These modified nanotubes packed into a solid-phase extraction column are used for the selective extraction and preconcentration of ultra-trace amounts of lead(II) from aqueous samples prior to electrothermal atomic absorption spectroscopy determination. The thiourea functional groups act as chelating agents for lead ions retaining them and so, give the selectivity to the sorbent. Elution of the retained ions can be performed using an acidic thiourea solution. The effects of experimental parameters including pH of the aqueous solution, type and amount of eluent, and the flow rates of sample and eluent solutions on the separation efficiency are investigated. The linear dependence of absorbance of lead on its concentration in the initial solution is in the range of 0.5-40.0 ng/mL with the detection limit of 0.13 ng/mL (3(Sb)/m, n = 10). The proposed method is applicable to the analysis of red lipstick, pine leaves, and water samples for their lead contents.

Ionothermal synthesis of magnetic N-doped porous carbon to immobilize Pd nanoparticles as an efficient nanocatalyst for the reduction of nitroaromatic compounds.

Carbon materials play important roles as catalysts or catalyst supports for reduction reactions owing to their high porosity, large specific surface area, great electron conductivity, and excellent chemical stability. In this paper, a mesoporous N-doped carbon substrate (exhibited as N-C) has been synthesized by ionothermal carbonization of glucose in the presence of histidine. The N-C substrate was modified by Fe3O4 nanoparticles (N-C/Fe3O4), and then Pd nanoparticles were stabilized on the magnetic substrate to synthesize an eco-friendly Pd catalyst with high efficiency, magnetic, reusability, recoverability, and great stability. To characterize the Pd/Fe3O4-N-C nanocatalyst, different microscopic and spectroscopic methods such as FT-IR, XRD, SEM/EDX, and TEM were applied. Moreover, Pd/Fe3O4-N-C showed high catalytic activity in reducing nitroaromatic compounds in water at ambient temperatures when NaBH4 was used as a reducing agent. The provided nanocatalyst's great catalytic durability and power can be attributed to the synergetic interaction among well-dispersed Pd nanoparticles and N-doped carbonaceous support.

Preparation of magnetic biochar functionalized by polyvinyl imidazole and palladium nanoparticles for the catalysis of nitroarenes hydrogenation and Sonogashira reaction.

Catalysts are essential materials in biotechnology, medicine, industry, and chemistry. On the other hand, recycling and using waste materials is important in economic efficiency and green chemistry. Thus, biochar was prepared from the stem and roots of the Spear Thistle to recover waste. After magnetizing the biochar, its surface was modified with polyvinyl imidazole. Finally, this modified biochar was decorated with Pd nanoparticles and used as a selective and recyclable nanocatalyst in the hydrogenation of nitroarenes and the Sonogashira reaction. The structure of this organic-inorganic nanocatalyst has been characterized by FESEM-EDS, XRD, FT-IR, TEM, and VSM techniques. In the hydrogenation reaction with the amount of 30 mg of nanocatalyst, the temperature of 50 °C in the water solvent, the reaction efficiency reached 99% for 30 min. In addition, under optimal conditions for the Sonogashira reaction: 1.0 mmol iodobenzene, 1.2 mmol phenylacetylene, 20 mg MBC-PVIm/Pd, 2 mmol K2CO3 in H2O at 50 C for 15 min, the reaction efficiency reached 95%. The recyclability of magnetic nanocatalysts was investigated and recognized this nanocatalyst can be used several times without notable loss of its activity.

The preparation of polyvinyl imidazole-functionalized magnetic biochar decorated by silver nanoparticles as an efficient catalyst for the synthesis of spiro-2-Amino-4H-pyran compounds.

The silver nanoparticle was synthesized by developing poly (1-vinylimidazole) on the surface of magnetized biochar (the stem and roots of Spear Thistle) (biochar/Fe3O4/PVIm/Ag). This nanocomposite was characterized by Fourier-transformed infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), and transmission electron microscopy (TEM). The SEM and TEM images of the nanocatalyst, biochar/Fe3O4/PVIm/Ag-NPs, confirmed the observation of microscopic sheets of biochar. The catalytic activity of these Ag NPs was tested via multicomponent reaction plus reusing to successful formation of 2-amino-4H-pyran and functionalized spirochromen derivatives. The prepared nanocatalyst was easily separated by an external magnet and reused in repeating coupling reaction cycles four times without remarkable activity loss. The catalyst showed great efficiency and reusability, thus making it an ideal candidate for catalytic purposes in several organic transformations.

WO3 nanoplates decorated with polyaniline and CdS nanoparticles as a new photocatalyst for degradation of imidacloprid pesticide from water.

This study focused on the photocatalytic degradation of imidacloprid (IM) in water as the model pesticides. The effective division of photogenerated charge carriers is important in the photocatalytic reactions. So, a new PANI/WO3-CdS photocatalyst was synthesized by a simple method. The prepared PANI/WO3-CdS nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy compatible with energy dispersive spectroscopy (FESEM-EDS), and X-ray diffraction (XRD). Degradation of IM pesticide under visible light irradiation was carried out to investigate the photocatalytic efficiency of the prepared nanocomposite. The effect of operational parameters on the degradation performance of pesticides was studied by response surface methodology (RSM). The optimum conditions for photocatalytic degradation of IM (94.7%) were found to be 10 ppm of IM, 150 mg of PANI/WO3-CdS, and pH = 3.0. The apparent rate constant of IM photodegradation over PANI/WO3-CdS was 0.016 min-1. According to results, PANI/WO3-CdS can serve as an efficient, and recyclable photocatalyst for imidacloprid degradation in an aqueous media.

Synthesis and photocatalytic activity of porous ZnO stabilized by TiO2 and Fe3O4 nanoparticles: investigation of pesticide degradation reaction in water treatment.

The present research studies the photocatalytic degradation of a pesticide using TiO2 and Fe3O4 nanoparticles supported on ZnO mesoporous (mZnO) substrate. Chlorpyrifos is an organophosphate pesticide with a C9H11Cl3NO3PS chemical formula. It is broadly utilized in agricultural fields to control product pests. The chlorpyrifos toxicity is acute and still dangerous to any aquatic organisms. The mZnO/TiO2-Fe3O4 material was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), and N2 adsorption and desorption (Brunauer-Emmett-Teller; BET). In order to optimize three important operating parameters, i.e., chlorpyrifos concentration, mZnO/TiO2-Fe3O4 nanocomposite amount, and pH, for photocatalytic degradation of chlorpyrifos, response surface methodology (RSM) was applied. The central composite design (CCD) including 20 experiments was used to conduct experiments. The highest photodegradation performance of about 94.8% was obtained for a chlorpyrifos concentration of 8 ppm, a pH of 10, and an amount of mZnO/TiO2-Fe3O4 nanocomposite of 60 mg. The degradation of chlorpyrifos using mZnO/TiO2-Fe3O4 presented good performance (more than 94%). The photocatalytic reaction followed pseudo-first-order kinetics with a rate constant of 0.058 min-1 for chlorpyrifos degradation. The results propose that mZnO/TiO2-Fe3O4 nanocomposite is a suitable alternative for the degradation of chlorpyrifos in aqueous solution. The improved photocatalytic efficiency could be attributed to the effective separation of electron-hole pairs via a Z-scheme mechanism.

Silver nanoparticle-decorated on tannic acid-modified magnetite nanoparticles (Fe3O4@TA/Ag) for highly active catalytic reduction of 4-nitrophenol, Rhodamine B and Methylene blue.

Tannic acid, as a humic-like substance with phenolic hydroxyl and carbonyl functional groups, can modify the surface of Fe3O4 nanoparticles (NPs). Moreover, it can improve surface properties and capacity of Fe3O4 for adsorption and reduction of silver ions through complexing with them, in aqueous solutions. Therefore, Fe3O4@TA NPs have potential of reducing, stabilizing and immobilizing silver nanoparticles to generate novel magnetic silver nanocatalyst. The nanocatalyst was characterized by several techniques such as Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP), Transmission electron microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDS), Vibrating Sample Magnetometer (VSM) and Fourier-transform infrared spectroscopy (FTIR). The results of characterization showed that the Fe3O4@TA/Ag nanocatalyst was successfully synthesized. It was observed that the Fe3O4@TA/Ag NP is the useful and recyclable, which can catalyze the reduction of different dyes, including 4-nitrophenol (4-NP), Rhodamine B (RhB), and Methylene blue (MB) in the presence of NaBH4 in the aqueous medium at room temperature. With the help of UV-Vis spectroscopy, catalysis reactions were controlled. According to results, these reactions followed the pseudo-first-order rate equation.

Ag-4-ATP-MWCNT electrode modified with dsDNA as label-free electrochemical sensor for the detection of daunorubicin anticancer drug.

This paper describes the synthesis of Ag-4-ATP-MWCNT nanocomposite and its use as a modifier of working electrode. The surface of the electrochemical Ag-4-ATP-MWCNT electrode was modified with a double-stranded DNA (dsDNA) to detect daunorubicin-DNA interactions. Differential pulse voltammetry was applied to develop an electroanalytical procedure for the determination of daunorubicin and evaluate its interaction with dsDNA immobilized on the electrode surface. After the optimization of operational parameters, the linear dependence of the peak current on the daunorubicin concentration was observed in the range of 0.10×10-8 to 1.00×10-5molL-1, with the detection and quantification limits of 3.00×10-10 and 1.00×10-9molL-1, respectively. The proposed biosensor was successfully applied to validate its capability for the determination of daunorubicin in human serum and urine samples.