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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 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]

Background: Tetracyclines (TCs) are a group of broad-spectrum antibiotics that may be used to control bacterial diseases in humans or are applied as feed additives to enhance growth in farm animals. TCs are released into the aquatic environment via different pathways. Many analytical methods combined with a preconcentration step have been introduced for the determination of TC in various environmental samples. Objective: The objective this paper is developing reliable analytical methods for determination of TC trace in various environmental samples. Method: In the present work, combined ultrasound-assisted and dispersive liquid-liquid microextraction according to the solidification of floating organic drop as a sample preconcentration procedure for determining TC hydrochloride HPLC in water and serum samples was used. Results: A series of parameters, including the type and volume of disperser and extraction solvents, salt effect, extraction time, and pH of solution influencing the extraction efficiency of UA-DLLME-SFO was examined. Enrichment factors were in the range of 125-137 for TC hydrochloride under optimum conditions. The linear range was calculated from 0.005 to 3 mg/L and LOD at 0.002 mg/L. RSDs were in the range of 2.7 to 3.2 (n=5). The UA-DLLME-SFO method used in water and serum samples revealed good extraction recoveries with RSD of 2.7-4.3%. Conclusions: This method significantly decreased the organic solvent volume from 3mL to 90 mL, also LOD and linear ranges were lower than or almost close to levels obtained in other research studies. In this procedure, an ultrasound bath enhanced the mixing and contact between the sample solution and the extraction solvent. [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]

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]