Artificial Neural Network (ANN) Method for Modeling of Sunset Yellow Dye Adsorption Using Nickel Sulfide Nanoparticle Loaded on Activated Carbon: Kinetic and Isotherm Study

In this paper, the NiS nanoparticles are prepared and characterized by x-ray powder diffraction and scanning electron microscopy. The NiS nanoparticles showed the excellent adsorption properties toward sunset yellow (UA) dye. The effect of solution pH, adsorbent dosage (0.005–0.020 g), contact time (0.5–30 minutes), and initial UA concentration (5–40 mg L^?1) on the extent of adsorption was investigated and modeled by artificial neural network. The experimental equilibrium data was analyzed by Langmuir, Freundlich, Tempkin, and D–R isothermal models. It was seen that the data was well presented by Langmuir model with a maximum adsorption capacity of 333.3 mg g^?1 at 26°C. Kinetic studies at various adsorbent dosages and initial UA concentrations show that high removal percentage (>90%) was achieved within 15 minutes. The adsorption of UA follows the pseudo-second-order rate model. The experimental data were applied to train the multilayer feed-forward neural network with three inputs and one output with Levenberg–Marquart algorithm and different numbers of neurons in the hidden layer. The minimum mean square error of 0.0003 and determination coefficient of (R²) 0.99 were found.     

Application of an optimized dispersive nanomaterial ultrasound‐assisted microextraction method for preconcentration of carbofuran and propoxur and their determination by high‐performance liquid chromatography with UV detection

An extraction method based on dispersive nanomaterial ultrasound‐assisted microextraction was used for the preconcentration of carbofuran and propoxur insecticides in water samples prior to high‐performance liquid chromatography with UV detection. ZnS:Ni nanoparticles were synthesized based on the reaction of the mixture of zinc acetate and nickel acetate with thioacetamide in aqueous media and then loaded on activated carbon (ZnS:Ni‐AC). Different methods were used for recognizing the properties of ZnS:Ni‐AC and then this nanomaterial was used for extraction of carbamate insecticide as new adsorbent. The influence of variables on the extraction method (such as amount of adsorbent (mg: NiZnS‐AC), pH and ionic strength of sample solution, vortex and ultrasonic time (min), ultrasound temperature and desorption volume (mL) was investigated by a screening 2^7–4 Plackett–Burman design. Then the significant variables were optimized by using a central composite design combined with a desirability function. At optimum conditions, this method had linear response >0.0060–10 μg/mL with detection limit 0.0015 μg/mL and relative standard deviations <5.0% (n = 3).     

Solid phase extraction and spectrophotometric determination of trace amounts of thiocyanate in real samples

A simple, selective and rapid method for solid phase extraction and spectrophotometric determination of thiocyanate using a manganese (III) tetrakis (p-sulfonatophenyl) porphyrin, [Mn (TPPS) OAC] bound to Amberlite IR-400 has been developed. The influence of pH, amount of solid phase, sample matrix, type and amount of eluting agent and flow rates i.e. variables affecting the efficiency of the extraction system were evaluated and conditions of the sample, eluting solution and active phase were optimized. The maximal capacity was found to be as 1.16 microg mL(-1) for 1200 mL. Thiocyanate ions can be eluted quantitatively with 8 mL 0.3 M ferric chloride. The enrichment factor was 150. The linear range of the determination is between 0.4-2.0 microg mL(-1) for preconcentration method with a limit of detection of 2.8 ng mL(-1). The method has been successfully applied for determination of trace amounts of thiocyanate in tap water, saliva sample and a synthetic mixture.     

Sensitized spectrophotometric determination of Cr(III) ion for speciation of chromium ion in surfactant media using alpha-benzoin oxime

A simple and accurate micellanized spectrophotometric method for determination of trace amounts of Cr(III) ion in tab and top water and a synthetic mixture has been described. The micellar method is based on effect of organized molecular assemblies such as micelles in spectrophotometric measurement due to their effect on the systems of interest. The ability of micellar system in solubilizing of sparingly soluble ligand or complexes has been used for increasing figures of merit of an analytical method. Due to solubility increasing in aqueous media requirement for a primary extraction can be eliminated. Using the alpha-benzoin oxime (alpha-BO) spectrophotometric determination of Cr(III) ion has been performed and results are compared. The spectrophotometric determination of Cr(III) ion using alpha-BO in the presence of non-ionic surfactant Triton X-100 has been performed. The influence of type and amount of surfactant, pH, complexation time and amount of ligand were examined. Finally, the repeatability, accuracy and the effect of interfering ions on the determination of Cr(III) ion was evaluated. The proposed methods successfully with recovery yield of almost 100% have been applied to the rapid and simple determination of Cr(III) ion in the real samples. There is a good agreement between methods and atomic absorption spectrometry. The Beers law is obeyed over the concentration range of 0.1-13.7 microg mL(-1) for micellar media. The detection limit is 0.8 ng mL(-1). The molar absorptivity of complex is 5350 L mol(-1) cm(-1).     

Development of efficient method for preconcentration and determination of copper, nickel, zinc and iron ions in environmental samples by combination of cloud point extraction and flame atomic absorption spectrometry

A cloud point extraction procedure for the preconcentration of copper, nickel, iron and zinc ions in various samples has been described. Analyte ions in aqueous phase are complexed with 3-((indolin-3-yl)(phenyl)methyl)indoline (IYPMI) and following centrifugation quantitatively extracted to the aqueous phase rich in Triton X-114. The surfactant-rich phase was dissolved in 2.0 mol L⁻¹ HNO₃ in methanol prior to metal content determination by flame atomic absorption spectrometry (FAAS). The effects of some parameters including, the concentrations of IYPMI, Triton X-114 and HNO₃, bath temperature, centrifuge rate and time were investigated on the recoveries of analyte ions. At optimum conditions, the detection limits of (3 SDb m⁻¹) of 1.6, 2.8, 2.1 and 1.1 ng mL⁻¹ for Cu²⁺, Fe³⁺, Ni²⁺ and Zn²⁺ along with preconcentration factors of 30 and enrichment factor of 48, 39, 34 and 52 for Cu²⁺, Ni²⁺, Fe³⁺ and Zn²⁺ respectively, were obtained. The proposed cloud point extraction has been successfully applied for the determination of metal ions in real samples with complicated matrix such as biological, soil and blood samples with high efficiency.      

Highly selective and sensitized spectrophotometric determination of iron (III) following potentiometric study

A simple, selective and sensitized spectrophotometric method for determination of trace amounts of Fe3+ ion in tap and waste water solutions has been described. The spectrophotometric determination of Fe3+ ion using Ferron in the presence of N,N-Dodecytrimethylammonium bromide (DTAB) has been carried out. The Beer's law is obeyed over the concentration range of 0.05-2.6 microg mL(-1) of Fe3+ ion with the relative standard deviation (RSD %) <0.2% and the molar absorptivity of complexes in pH 3.5 is 3.8 x 10(3) L mol(-1) cm(-1). Potentiometric pH titration has been used for prediction of protonation constants of ferron, and evaluating its stoichiometry and respective stability constant with Fe3+ ion. As it is obvious the most likely species of ferron alone and its complexes are LH (log = 7.64), LH2 (logK = 10.52), LH3 (logK = 11.74) and ML2 (logbeta = 23.68), ML3 (logbeta = 23.68), ML3H (logbeta = 23.68), ML3H2 (logbta = 23.68) and ML(OH)2 (logbeta = 23.68) respectively.     

Highly selective and sensitive spectrophotometric determination of trace amounts of silver ion in surfactant media using 2-mercaptobenzoxazole

A simple and accurate spectrophotometric method for determination of trace amounts of silver ion in tap and wastewater solution and photographic solutions has been described. The spectrophotometric determination of silver ion using 2-mercaptobenzoxazole (MBO) in the presence of Triton X-100 as nonionic surfactant has been carried out. The Beer's law is obeyed over the concentration range of 0.1-9.0 microg mL(-1) of Ag+ ion with the detection limits of 1.6 ng mL(-1). The influence of type and amount of surfactant, pH, complexation time and amount of ligand on sensitivity of method were optimized. Finally the repeatability, accuracy and the effect of interfering ions on the determination of silver ion were evaluated. There is a good agreement between results of proposed method and atomic absorption spectrometry.     

Ionic‐liquid‐based surfactant‐emulsified microextraction procedure accelerated by ultrasound radiation followed by high‐performance liquid chromatography for the simultaneous determination of antidepressant and antipsychotic drugs

In the present work, an efficient and environmental friendly method of ionic‐liquid‐based emulsified microextraction procedure accelerated by ultrasound radiation has been developed. Subsequently, its performance was compared with dispersive liquid–liquid microextraction and ultrasound‐assisted surfactant‐based emulsification microextraction methods. The optimization of experimental conditions was carried out by combination of central composite design and response surface methodology. The optimum conditions of variables were set as follows: 50 μL of 1‐hexyl‐3‐methylimidazolium hexafluorophosphate (extracting solvent), 10 min ultrasound time, and 10 min vortex time for agitating 6 mL sample solution in pH 3 in the presence of 4 mg sodium dodecyl sulfate without addition of salt and 200 μL of methanol as diluent solvent. Under these conditions, the responses are linear for doxepin and perphenazine in the range of 0.3–1000 and 5–1000 μg/L, respectively. The limits of detection were 0.1 μg/L for doxepin and 1 μg/L for perphenazine. Relative standard deviations were lower than 3.5 for the determination of both species. Finally, the method was used for the preconcentration and determination of doxepin and perphenazine in urine sample with relative recoveries in the range of 89–98%.     

Construction of molecularly imprinted nanoparticles by employing ultrasound waves for selective determination of doxepin from human plasma samples: Modeling and optimization

In this work, molecularly imprinted nanoparticles (MINPs) were applied as selective adsorbent for ultrasound‐assisted micro‐solid‐phase extraction (UAMSPE) of doxepin (DP) from human plasma samples, which was then cleaned up, pre‐concentrated and subjected to HPLC. The MINPs were synthesized based on a non‐covalent approach by precipitation polymerization utilizing methacrylic acid and styrene as functional monomers, DP as template, ethylene glycol dimethacrylate as cross‐linker and 2,2‐azobisisobutyronitrile (AIBN) as initiator. The obtained MINPs were characterized by Fourier transform‐infrared and field emission scanning electron microscopy. Factors influencing the efficiency of UAMSPE such as sonication time, volume of eluent solvent and amount of sorbent were investigated using a central composite design and the optimal points were identified as 4 min of sonication time, 380 μL of eluent solvent and 30 mg of sorbent. Under optimized conditions, the proposed method has linear responses in the range of 0.2–2000 ng mL^–1, with a satisfactory limit of detection of 0.04 ng mL^–1 and limit of quantification of 0.11 ng mL^–1.