Investigation of adsorption performance of graphene oxide/polyaniline reinforced hollow fiber membrane for preconcentration of Ivermectin in some environmental samples

Electrochemical Detection of Nitrite on PANI-TiO2/Pt Nanocomposite-Modified Carbon Paste Electrodes Using TOPSIS and Taguchi Methods

Platinum nanoparticles are widely used in electrocatalysis and sensors. In this work, a novel modified carbon paste electrode based on PANI-TiO2/Pt nanocomposites was developed electrochemically. To improve the performance of the PANI-TiO2/Pt composite-modified electrode, a Taguchi orthogonal array was used for experimental design, and the best values of factors affecting the performance were determined using the technique for order preference by similarity to ideal solution (TOPSIS) and Taguchi optimization methods. The electrochemical catalytic activities of the PANI-TiO2/Pt composite-modified electrode on the oxidation of nitrite was calculated by electrochemical analysis. The experimental results demonstrate that the PANI-TiO2/Pt electrode has pretty excellent electrocatalytic ability for the oxidation of nitrite. The sensing performances of the proposed electrode were evaluated, including linear detection range, sensitivity, LOD, selectivity, and stability for nitrite sensing.

Hybrid Nanocomposites Based on Poly(3,6-dianiline-2,5-dichloro-1,4-benzoquinone): Synthesis, Structure and Properties

Hybrid nanocomposites based on poly(3,6-dianiline-2,5-dichloro-1,4-benzoquinone) (PDACB) in salt form and graphene oxide (GO) have been obtained for the first time, and the significant influence of the preparation method on the composition and structure of nanocomposites and their functional properties has been demonstrated. Nanocomposites were prepared in three ways: via ultrasonic mixing of PDACB and GO; via in situ oxidative polymerization of 3,6-dianiline-2,5-dichloro-1,4-benzoquinone (DACB) in the presence of GO; and by heating a suspension of previously prepared PDACB and GO in DMF with the removal of the solvent. The results of the study of the composition, chemical structure, morphology, thermal stability and electrical properties of nanocomposites obtained via various methods are presented. Nanocomposites obtained by mixing the components in an ultrasonic field demonstrated strong intermolecular interactions between PDACB and GO both due to the formation of hydrogen bonds and π-stacking, as well as through electrostatic interactions. Under oxidative polymerization of DACB in the presence of GO, the latter participated in the oxidative process, being partially reduced. At the same time, a PDACB polymer film was formed on the surface of the GO. Prolonged heating for 4 h at 85 °C of a suspension of PDACB and GO in DMF led to the dedoping of PDACB with the transition of the polymer to the base non-conductive form and the reduction of GO. Regardless of the preparation method, all nanocomposites showed an increase in thermal stability compared to PDACB. All nanocomposites were characterized by a hopping mechanism of conductivity. Direct current (dc) conductivity σdc values varied within two orders of magnitude depending on the preparation conditions.

Conductive Polymer-Based Nanocomposites as Powerful Sorbents: Design, Preparation and Extraction Applications

Conductive polymers as composite materials have been attracted tremendous attention due to their versatile and excellent features such as tunable conductivity, facile synthesis and fabrication, high chemical and thermal stability etc. These characteristics make them versatile and let them being used in numerous fields including microelectronics, optics and biosensors. Throughout the mentioned fields, conductive polymers particularly perform as effective sorbents. Although tremendous efforts have been put into this topic, to the best of our knowledge, a comprehensive up-to-date review on the applications of conductive polymers as efficient sorbents has not been reported. The main objective of this paper is to make a significant contribution to the recent literature toward the synthesis and extraction applications of conductive polymers as efficient sorbents.

Miniaturized green sample preparation approaches for pharmaceutical analysis

The development of green sample preparation procedures is an extremely important research field in which more and more applications are constantly being proposed in different areas, including pharmaceutical analysis. This review article is aimed at providing a general overview of the development of miniaturized green analytical sample preparation procedures in the pharmaceutical analysis field, with special focus on the works published between January 2017 and July 2021. Particular attention has been paid to the application of environmentally friendly solvents and sorbents as well as nanomaterials or high extraction capacity sorbents in which the solvent volumes and reagents amounts are drastically reduced, with their subsequent advantages from the sustainability point of view.

A critical review on environmental presence of pharmaceutical drugs tested for the covid-19 treatment

On March 11, 2020, the World Health Organization (WHO) declared COVID-19 a pandemic. The outbreak caused a worldwide impact, becoming a health threat to the general population and its professionals. To date, there are no specific antiviral treatments or vaccines for the COVID-19 infection, however, some drugs are being clinically tested. The use of these drugs on large scale raises great concern about their imminent environmental risk, since the elimination of these compounds by feces and urine associated with the inefficiency of sewage treatment plants in their removal can result in their persistence in the environment, putting in risk the health of humans and of other species. Thus, the goal of this work was to conduct a review of other studies that evaluated the presence of the drugs chloroquine, hydroxychloroquine, azithromycin, ivermectin, dexamethasone, remdesivir, favipiravir and some HIV antivirals in the environment. The research indicated the presence of these drugs in the environment in different regions, with concentration data that could serve as a basis for further comparative studies following the pandemic.

Utilizing eco-friendly kaolinite-biochar composite adsorbent for removal of ivermectin in aqueous media

Several emerging contaminants are currently used in an unregulated manner worldwide, resulting in their increasing stringent limits in water by regulatory bodies. Thus, more viable and cheap treatment technologies are required. Recently, synergistic combinations of low-cost adsorbents have shown huge potential for aqueous toxic metals adsorption in water treatment processes. However, there is dearth of data on their potential for emerging contaminant removal. Here, low-cost kaolinite (KAC) clay was synergistically combined with blended Carica papaya or pine cone seeds, and calcined to obtain composites of KAC-Carica papaya seeds (KPA) and KAC-pine cone seeds (KPC). These adsorbents were characterized and evaluated for ivermectin adsorption at varying operating times (15-1440 min), pH (3-11), concentration (100-600 μg/L), and temperature (19.5-39.5 °C), as well as testing adsorbents' reusability. The composites exhibited marked property differences including over 250% cation exchange capacity increases and ≥50% surface area decreases, but unchanged KAC clay primary lattice structure. Ivermectin adsorption data were explained using kinetics and adsorption isotherm models. The rate of adsorption on KAC decreased over time, while rates for KPA and KPC increased until equilibrium at 180 min; the presence of biomaterials in the composites conferred better ivermectin adsorption and retention under continuous agitation. The adsorbents exhibited dual adsorption peaks one each at the acidic and alkaline pH regions as solution pH changed from 3 to 11. The rate data fitted (≥0.9232) the homogeneous fractal Pseudo-Second Order (FPSO) better than any other kinetics model, as well as the Freundlich adsorption isotherm model (≥0.9887); these indicate complex interactions between ivermectin and the adsorption sites of both composites. Ambient temperature increase up to ≈30 °C caused higher ivermectin adsorption but beyond this temperature there was drastic drop in adsorption. The KPA and KPC adsorption capacities are 105.3 and 115.8 μg/g, respectively. The KPC was better at reducing ivermecitn in low-concentration solution (≈75 μg/L) to less than 5.0 μg/L compared with KPA with ≈20.0 μg/L. Though KPC showed better efficiency in adsorption capacity and lowering concentration in low-concentration solutions, KPA exhibited better reusability with 83.5 and 67.5% initial adsorption strengths remaining in the second and third adsorption cycles, respectively, compared to the 73.8 and 58.8% for the KPC. These results indicate that KPA and KPC composites have the economic potential for application in water treatment processes.

An in-silico layer-by-layer adsorption study of the interaction between Rebaudioside A and the T1R2 human sweet taste receptor: modelling and biosensing perspectives

The human sweet taste receptor (T1R2) monomer-a member of the G-protein coupled receptor family that detects a wide variety of chemically and structurally diverse sweet tasting molecules, is known to pose a significant threat to human health. Protein that lack crystal structure is a challenge in structure-based protein design. This study focused on the interaction of the T1R2 monomer with rebaudioside A (Reb-A), a steviol glycoside with potential use as a natural sweetener using in-silico and biosensing methods. Herein, homology modelling, docking studies, and molecular dynamics simulations were applied to elucidate the interaction between Reb-A and the T1R2 monomer. In addition, the electrochemical sensing of the immobilised T1R2-Reb-A complex with zinc oxide nanoparticles (ZnONPs) and graphene oxide (GO) were assessed by testing the performance of multiwalled carbon nanotube (MWCNT) as an adsorbent experimentally. Results indicate a strong interaction between Reb-A and the T1R2 receptor, revealing the stabilizing interaction of the amino acids with the Reb-A by hydrogen bonds with the hydroxyl groups of the glucose moieties, along with a significant amount of hydrophobic interactions. Moreover, the presence of the MWCNT as an anchor confirms the adsorption strength of the T1R2-Reb-A complex onto the GO nanocomposite and supported with electrochemical measurements. Overall, this study could serve as a cornerstone in the development of electrochemical immunosensor for the detection of Reb-A, with applications in the food industry.

Combining graphite with hollow-fiber liquid-phase microextraction for improving the extraction efficiency of relatively polar organic compounds

In this study, we have developed a simple and effective hybrid extraction method based on the incorporation of raw carbon nanosorbents and octanol in the pores of a hollow-fiber membrane for improving the extraction efficiency of relatively polar organic compounds. Trihalomethanes (THMs) were used as model analytes. Three types of carbon nanosorbents (graphite, graphene, and multi-walled carbon nanotubes) were studied. The carbon sorbent incorporating membrane was used in a two-phase mode liquid-phase microextraction, with 1-octanol as the acceptor solution. Using a graphite-reinforced hollow-fiber membrane and an extraction time of 10 min, enrichment factors of 40-71 were obtained for trichloromethane, bromodichloromethane, bromoform, and chlorodibromomethane. Linear working ranges of 0.2-100 μg L^-1 and limits of detection ranging from 0.01 μg L^-1 (for CHCl₂Br and CHClBr₂) to 0.1 μg L^-1 (for CHCl₃) were achieved. The minimum detectable concentrations were far below the maximum concentration levels (60-200 μg L^-1) set by the WHO for drinking water. The carbon-sorbent-reinforced hollow-fiber liquid-phase microextraction afforded higher extraction efficiency and shorter extraction time compared with conventional hollow-fiber liquid-phase microextraction. Finally, the method was applied to the analysis of real water samples, such as drinking water, tap water, and swimming pool water samples.