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In the present study, titanium oxide (TiO2) nanoparticles, chitosan, and several nanocomposites containing different mass dosages of TiO2 and chitosan have been applied as the adsorbent for COD removal from the industrial wastewater (Bouali Sina Petrochemical Company, Iran). The FESEM, XRD, and FTIR tests have been employed to characterize TiO2 nanoparticles, chitosan, and fabricated nanocomposites. Then, the effect of adsorption parameters, including TiO2–chitosan mass ratio (1:1, 1:2, and 2:1), adsorbent content (0.25–2.5 g), temperature (20–50 °C), pH (3–11), solution volume (100–500 mL), and contact time (30–180 min) on the COD reduction has also been monitored both experimentally and numerically. The Box–Behnken design of the experiment approves that TiO2–chitosan (1:1), adsorbent content of 2.5 g, temperature = 20 °C, pH 7.4, solution volume of 100 mL, and contact time = 180 min are the condition that maximizes the COD removal (i.e., 94.5%). Moreover, the Redlich–Peterson and Pseudo-second order models are the best isotherm and kinetic scenarios to describe COD removal's transient and equilibrium behaviors. The maximum monolayer COD adsorption capacity of the TiO2–chitosan nanocomposite is 89.5 mg g−1. The results revealed that the industrial wastewater COD is better to remove using the TiO2–chitosan (1:1) at temperature = 20 °C. [ABSTRACT FROM AUTHOR]

In this paper, effervescence‐assisted dispersive liquid–liquid microextraction (EADLLME), based on hydrophobic deep eutectic solvent (HDES) was developed as a green, simple, fast, and sensitive method for the extraction and preconcentration of captopril (CAP) from tablet and urine samples, followed by UV–Vis spectrophotometry. Initially, acetic acid was added to the green extraction solvent (HDES) at μL‐level. This mixture was then transferred by a syringe into bicarbonate fortified sample (contains complex of Ni [II] with CAP); an effervescence reaction occurred immediately between the acetic acid (AA) and sodium bicarbonate. The produced CO2 bubbles led to the dispersion of HDES into the sample. The resulting fine droplets from extractant dispersion facilitated the phase separation. After that, the absorbance of upper phase (HDES rich phase) was measured at 340 nm. Under optimized conditions, we achieved a desirable linearity in the range of 0.07–30 μg/L and low limits of detection of 0.04 μg/L. This developed method was successfully applied for the analysis of tablet and urine samples. [ABSTRACT FROM AUTHOR]

In this research, a simple and sensitive electrochemical technique based on using nanocomposite of (AgNP/CuMOF/PPy–rGO) modified carbon paste electrode for determination of metronidazole (MTZ) is described. Polypyrrole (PPy) hemispherical molecules coated reduced graphene oxide (PPy–rGO) was combined with CuMOF, a typical metal–organic framework, by hydrothermal method. AgNP/CuMOF/PPy–rGO was simply fabricated by creating AgNP inside and on the surface of the nanocomposite. The composition and morphology of the synthesized nanocomposite were investigated by SEM, FT‐IR, EDX, and XRD. Cyclic voltammetry and ASSWV were utilized to determine the electrocatalytic activity of the sensor regarding the reduction of MTZ. Interestingly, some outstanding properties of the nanocomposite including high surface area of CuMOF, good conductivity of PPy–rGO, and the catalytic activity of AgNPs could result in the enhancement of the electron transfer rate, electrochemical behavior, and the reduction of peak currents at the surface of the proposed sensor. Sensitive, promising, and stable electrochemical sensor exhibited linear detection range of 0.08–160 μM at pH 5.0 with detection and limit of 24 nM (S/N = 3). The system was validated for precision with standard deviation less than 2.0%. Moreover, its feasibility was successfully assessed through analysis of tablet and human urine. [ABSTRACT FROM AUTHOR]

A new imidazole-2-thione based copper coordination polymer namely [Cu2(ebit)Br2]n (1) [ebit = 1,1′-(1,2-ethanediyl)bis(3-methyl-imidazole-2-thione)] was synthesized by a layer diffusion method, and [(C10H14N4S)CuBr3] (2) was a by-product of 1 and was obtained through redox processes between the ligand and metal ion. Polymer 1 was fully characterized by IR, CHNS, PL, TGA, PXRD and single crystal X-ray diffraction analysis. In polymer 1, the copper atom is coordinated by two bridging bromides and two sulfur atoms from two ebit ligands with a distorted tetrahedral geometry to form a 2D honeycomb network, while in 2, the copper atom is coordinated only by three bromide atoms to create the anionic part of the compound and stabilized by the cationic moiety of the ligand. Both compounds have expanded into 3D networks through intermolecular interactions. The adsorption ability of polymer 1 toward four dyes namely Congo Red (CR), Aniline Blue (AB), Malachite Green (MG) and Victoria Blue (VB) was investigated and the results indicated that the title polymer has excellent adsorption capacity towards these dyes. Adsorption kinetics and isotherms and the adsorption mechanism were also analyzed. Polymer 1 was converted to nanospheres 1 by an ultrasonic method and used as a precursor for the preparation of CuO nanospheres. The obtained metal oxide was characterized by SEM, TEM, EDX, PXRD and IR. The results of photocatalytic and antimicrobial tests revealed that the CuO nanospheres showed good performances for the degradation of Rhodamine B and good antibacterial activity. [ABSTRACT FROM AUTHOR]

To understand toxic effect of Zn oxide nanoparticles (ZnO NPs) on Chenopodium murale, 40-day-old plants were exposed to 10, 50, and 250 mg L−1 of NPs using hydroponic system under controlled light and temperature conditions. Aboveground parts and roots were harvested 3 and 6 days after treatments and evaluated for some growth and biochemical indices. By increasing the concentration of ZnO NPs, the content of Zn increased in the roots more than the shoots. Our findings showed that all ZnO NPs treatments resulted in a decrease in growth, total chlorophyll content and soluble proteins, while the content of carotenoids, lipid peroxidation, leaf hydrogen peroxide (H2O2), and leaf electrolyte leakage increased significantly compared with the control. These changes, along with increased proline content and catalase (CAT), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) activities in the treated plants, suggest that all concentrations of ZnO NPs used in this study strongly induced oxidative stress. A decline in growth-related indicators can be considered as an indicator of ZnO NPs phytoxicity in C. murale. Based on the concentration of Zn dissolved in the solution, the effects of Zn released into the nutrient solution may be greatly involved in induction of toxicity and retardation of growth at least under our experimental conditions. The results of this study suggest that an important mechanism of ZnO NPs phytotoxicity may be the exacerbation of oxidative stress and damage to biomembranes. [ABSTRACT FROM AUTHOR]

A new, simple, low cost, high efficiency, and rapid floating technique was developed for the determination of Sunset Yellow in beverage and effervescent vitamin C. The method is based on two main steps: 1)- formation of dye-surfactant complex by the addition of a cationic surfactant, cetyltrimethylammonium bromide, to the solution containing an anionic dye (Sunset Yellow) and 2)- flocculation of the dye-surfactant complex with the participation of sodium perchlorate as a coagulant followed by aggregation and enlargement of the flocs while floating at the top of the solution. After the extraction, separated and preconcentrated Sunset Yellow was investigated by spectrophotometric determination. IR spectrum, scanning electron microscopy (SEM), and light microscopy were used to characterise the flocs. The effects of different parameters such as pH, concentration of surfactant, concentration of sodium perchlorate, and temperature on the extraction of dye were investigated and optimized. Under optimum conditions, a linear calibration curve was obtained in the range of 0.05–5 mg L−1. The detection limit (3Sb/m) was 0.02 mg L−1 with a preconcentration factor of 25. The relative standard deviation (RSD) for 0.1 mg L−1 of Sunset Yellow was 2.6% (n = 10). The applicability of the method was evaluated by measuring the amount of dye in beverage and effervescent vitamin C. Interferences of typical cations and anions which may participate in the matrices were also checked. The amount of Sunset Yellow found in real samples was 1.32–3.89 mgL−1. [ABSTRACT FROM AUTHOR]

A new electrochemical probe for detecting Isoniazid is proposed based on nanocomposite electrode modified with nanoceria particles (CeO2 NPs) as a catalytic amplifier. The main reason for the catalytic activity of CeO2 NPs attributed to their reversible dual oxidation states Ce(III)/Ce(IV) in that CeO2 NPs. Nanoceria nanoparticles have the ability to change redox states and surface properties when being in contact with electroactive compounds. Therefore, valence and defect structure of CeO2 NPs play a mainly role in this electrocatalytic reaction. Electrode surface area (A), electron transfer coefficient (α), and heterogeneous catalytic rate constant (Kh) were estimated by electrochemical techniques. The peak current is found to depend linearly on isoniazid concentration within the ranges of 5.0-140.0 µmol L-1. The limit of detection (LOD) for isoniazid is found to be 0.51 µmol L-1. Finally, the modified electrode receives many advantages such as notable catalytic activity, and acceptable reproducibility, the proposed method was used for determining isoniazid in urine and tablet samples successfully. [ABSTRACT FROM AUTHOR]

The presence of antibiotics in the environment threatens the health of humans and animals, seriously. In this respect, this study applies cerium oxide nanoparticles (CeO2 NPs) as an adsorbent to remove tetracycline (TC) from aqueous solutions and investigates the effects of various parameters on the adsorption reaction. The studied parameters include pH‚ electrolyte concentration‚ TC concentration, amount of the adsorbent, flow rate of the solution, and the presence of several coexisting ions. According to the obtained results, the CeO2 NPs are quite efficient for removal of TC at room temperature. Furthermore, adsorption of TC onto the CeO2 NPs is fast and the corresponding isotherms fit the Langmuir model, perfectly. The proposed adsorption method is successfully employed to remove TC from various aqueous solutions including surface and drinking water samples. [ABSTRACT FROM AUTHOR]

Herein, magnetically hollow zein nanoparticles were synthesized and used as a magnetic sorbent for the preconcentration of chlorpyrifos and its analysis by high-performance liquid chromatography (HPLC). Morphology of the sorbent was characterized by transmission electron microscopy (TEM). In this study, the effects of important parameters such as pH of the solution, adsorption and desorption time, type and volume of desorption solvent, and salt addition were investigated. Under optimized experimental conditions, the linear range was from 50 to 2000 μg mL−1, and an LOD of 25 μg L−1 was calculated. The relative standard deviations (RSD) varied from 3.8 to 5.1% (n = 5). The enrichment factors for 50 and 100 μg L−1 samples were calculated as 187 and 210, respectively. The developed method was successfully applied in soil and water samples and showed good extraction recoveries. [ABSTRACT FROM AUTHOR]

The authors report on the preparation of sol-gel coated magnetized carbon nanotubes whose surface were imprinted with Cd ions and the application of these materials on selective preconcentration of Cd ions in different water samples. FeO particles and tetraethyl orthosilicate were used as a magnetic ingredient and as a surface modifier for the carbon nanotubes, respectively. The Cd-imprinted polymer was prepared by grafting copolymerization of Cd ions as template, methacryloylsulfamethizole and 2-vinylpyridine as polymerizable ligands, methacrylic acid as functional monomer, and ethyleneglycoldimethacrylate as crosslinker. The resulting magnetic nanoparticles were characterized by Fourier transform infrared spectrometry, the Brunauer-Emmett-Teller method, and by scanning electron microscopy. Isothermal absorption, absorption kinetics and selectivity were studied in detail. The experimental conditions were optimized. Figures of merit include (a) a maximum adsorption capacity of 81 mg·g; (b) relative selectivity coefficients of 2.41, 2.36, 1.41, 1.66, and 1.70 for Cd/Ni, Cd/Co, Cd/Zn, Cd/Cu, and Cd/Pb, respectively; (c) a detection limit of 0.29 ng·mL, (d) an enrichment factor of 55.5; (e) an intra-day precisions of 1.13%; and (f) an inter-day precision of 1.39%. The method was successfully applied to the determination of cadmium in spiked samples including feed water of an ammonia production unit, tap water, industrial waste water from a petrochemical plant, river water from the Garrahi River, bay water from Khor Musa, and marsh water from the Shadegan wetland. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the behaviors and mechanisms of copper adsorption through highly efficient nanostructured superparamagnetic hydroxyapatite.

A new and simple hollow fiber liquid-phase microextraction was used in conjunction with HPLC for the extraction and quantitative determination of nalidixic acid (NA) in human urine samples. This study considers this technique an alternative to common methods of hollow fiber microextraction based on pH gradient and electromembrane extraction of NA in human urine samples. In this research, the drug was extracted from the source phase (donor phase) into a modified organic phase with Aliquat 336 (hydrophobic ion-pair reagent) as a carrier able to impregnate pores of the hollow fiber. In this study, the effects of several factors were tested on the extraction efficiency of the drug. Under optimum conditions, the linearity of the method was observed over the range 0.05-2.0 μg mL-1 with a correlation coefficient of r = 0.9983. The results of tests on the method determined a good sensitivity with a limit of detection of 0.008 μg mL-1. The intra-day relative standard deviation (n = 9) for 0.8 μg mL-1 was 6.2%, and the inter-day relative standard deviation (n = 5) for 0.8 μg mL-1 was 5.6%. This newstrategy was successfully applied to analyze a real urine sample with satisfactory results. [ABSTRACT FROM AUTHOR]

This study introduces a novel method of ultrasonic-assisted solid-phase extraction, pre-concentration, and reversed-phase high-performance liquid chromatography to determine nicotinamide (NAM) and nicotinic acid (NAC) from an aqueous solution using anthracite particles (ANTCs). Results demonstrated that ANTCs were quite efficient for use in extraction and pre-concentration of traces of NAM and NAC at 25 °C. Tests investigated the effects of the parameters: pH, buffer and its volume, electrolyte concentration, composition and volume of the desorbing solvent, accepted tolerable volume, amount of adsorbent, ultrasonic radiation time, and evidence of some co-existing ions on pre-concentration and determinations of NAM and NAC. The method showed good linearity for determination of these compounds in the range of 0.0025-10 μg mL with regression coefficients of 0.999. Evaluations for limits of detection were 6 × 10 and 7 × 10 μg mL for NAM and NAC, respectively. Intra- and inter-day relative standard deviations for 0.2 and 5 μg mL were below 3.5 % and 4.6 %, respectively. Samples of rice, coffee, spice, spaghetti, tea, and B-complex syrup with potential niacin content were used as real samples, and NAM and NAC in the samples and spiked samples were pre-concentrated and determined successfully. [ABSTRACT FROM AUTHOR]

Square-wave voltammetry is a fast technique used for determination of trace amounts of acrylamide. When cobalt(II) ions were added to the acrylamide solution, a catalytic peak at about -1.35 V vs. Ag/AgCl was observed, which was proportional to acrylamide concentration. The calibration curve showed good linearity in the range of 200-800 ng mL-1 of acrylamide with a regression coefficient of 0.9989. The limit of detection of the method was 3.52 ng mL-1, and the relative standard deviations for concentrations of 300 ng mL-1 and 700 ng mL-1 were 99.8% × 10-2 and 79.7% × 10-2, respectively. [ABSTRACT FROM AUTHOR]