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Zinc oxide and gold-zinc oxide (Au-ZnO) nanostructures with multiple rods (multipods) morphology were successfully prepared. Au-ZnO nanostructures were synthesized via a simple precipitation route method in the presence of oligoaniline-coated gold nanoparticles. The Au-ZnO catalyst obtained was applied for the degradation of methyl orange in an aqueous solution under UV irradiation. Effects of the operational parameters such as the solution pH, amount of photocatalyst, and dye concentration on the photocatalytic degradation and decolorization of methyl orange were studied. Detailed studies including kinetic study and regeneration of catalyst were carried out on the optimal conditions for the photodegradation of methyl orange by Au-ZnO multipods in aqueous solution. Effect of foreign species on the photodegradation of methyl orange was also studied. An enhancement of the photocatalytic activities for photodegradation of methyl orange was observed when the gold nanoparticles were loaded on the zinc oxide multipods. The proposed catalyst was applied for the degradation of methyl orange in synthetic wastewater samples with satisfactory results.

A new, simple, rapid, selective, and environmentally friendly method is proposed for the determination of Cu(II) ions based on the formation of the complex between these ions and salophen as the ligand followed by the dispersive liquid-liquid microextraction of the neutral hydrophobic complex formed in the organic phase and flame atomic absorption spectrophotometric detection. Various factors including the pH of the sample solution, concentration of salophen as the complexing reagent, type and volume of the extraction and disperser solvents, and extraction time affecting the extraction efficiency of Cu(II) ions and its subsequent analytical signal were studied and optimized. Under the optimized experimental conditions, the detection limit (3σ) and the enrichment factor were obtained to be 0.60 μg L −1 and 49, respectively, for 10.0 mL of the sample solution. The consumptive index was 0.20 mL and the calibration graph was linear in the range of 3.0-120 μg L −1. The relative standard deviations for six replicate measurements of 5.0, 20.0, and 50.0 μg L −1 of Cu(II) ions were 4.1%, 1.5%, and 1.8%, respectively. The proposed method was also successfully applied for the extraction and determination of Cu(II) ions in different water and food samples with satisfactory results.

A fast, sensitive, and convenient technique consisting of a miniaturized solid-phase extraction method named microextraction in packed syringe coupled with gas chromatography and mass spectrometry was developed for the preconcentration and determination of some pesticides, including hexachlorobenzene, heptachlor, alachlor, aldrine, and metolachlore, in natural water samples. Carboxyl-purified multiwalled carbon nanotubes were used as a sorbent in microextraction in packed syringe. Based on this technique, 6.0 mg of multiwalled carbon nanotubes was inserted in the syringe between two polypropylene frits. The analytes would be adsorbed on the solid phase, and would subsequently be eluted using organic solvents. The influence of some important parameters involved including the solution pH, type, and volume of the organic desorption solvent, and amount of the multiwalled carbon nanotubes sorbent on the extraction efficiency of the selected pesticides were investigated. The proposed method showed a good linearity in the range of 0.1-25.0 ng/mL and low limits of detection in the range of 0.02-0.19 ng/mL using the selected ion-monitoring mode. Reproducibility of the method was in the range of 3.3-8.5% for the studied pesticides. Also to evaluate the matrix effect, the developed method was applied to the preconcentration and determination of the selected pesticides in different water samples.