Development of microextraction methods for the determination of sulfamethoxazole in water and biological samples: modelling, optimization and verification by central composite design

This study aimed to preconcentration of sulfamethoxazole (SMX) in water and biological samples. Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and ultrasound-assisted dispersive solid-phase microextraction (UA-DSPME) methods paired with spectrophotometry were applied to extraction and preconcentration of SMX. ZnFe2O4 nanoparticles were prepared as adsorbent in UA-DSPME method by hydrothermal method. The scanning electron microscopy (SEM) technique showed that the adsorbent had symmetrical, bullet-shaped particles with uniform size. The results of the X-ray diffraction (XRD) showed the successful synthesis of the ZnFe2O4 nanoparticles. Effective parameters in extraction, including ultrasonication time, disperser solvent volume, adsorbent amount, extraction solvent volume, eluent volume, and pH were investigated and optimized. The practical and optimal conditions of the process were determined by the central composite design (CCD). The optimal conditions were 0.024 g of adsorbent, 535 µL of disperser solvent volume, 7.5 min of ultrasonication time, 235 µL of eluent volume, pH of 5, and 185 µL of extraction solvent volume. Linear ranges and detection limits were 20–1,200 μg L−1 and 6 μg L−1 for UA-DSPME and 10–800 μg L−1 and 3 μg L−1 for UA-DLLME. Relative standard deviation (RSD) of less than 4% were obtained for UA-DSPME and UA-DLLME methods. The reusability showed that the ZnFe2O4 adsorbent could extract SMX up to five cycles of adsorption/desorption without significant reduction in its efficiency. Also, interference studies showed that the presence of different cations and anions did not significantly interfere in the extraction of SMX. The outcomes of real-time samples analysis showed that the extraction of SMX for both methods was in the range of 92.44%–99.12%. The results showed the developed methods are simple, sensitive, and suitable for SMX preconcentration in environmental water and biological samples

The Effect of Plasticizers on the Polypyrrole-Poly(vinyl alcohol)-Based Conducting Polymer Electrolyte and Its Application in Semi-Transparent Dye-Sensitized Solar Cells

In this work, the quasi-solid-state polymer electrolyte containing poly(vinyl alcohol)-polypyrrole as a polymer host, potassium iodide (KI), iodine (I2), and different plasticizers (EC, PC, GBL, and DBP) was successfully prepared via the solution casting technique. Fourier transform infrared spectroscopy (FTIR) was used to analyze the interaction between the polymer and the plasticizer. X-ray diffraction confirmed the reduction of crystallinity in the polymer electrolyte by plasticizer doping. The ethylene carbonate-based polymer electrolyte showed maximum electrical conductivity of 0.496 S cm−1. The lowest activation energy of 0.863 kJ mol−1 was obtained for the EC-doped polymer electrolyte. The lowest charge transfer resistance Rct1 was due to a faster charge transfer at the counter electrode/electrolyte interface. The polymer electrolyte containing the EC plasticizer exhibited an average roughness of 23.918 nm. A photo-conversion efficiency of 4.19% was recorded in the DSSC with the EC-doped polymer electrolyte under the illumination of 100 mWcm−2

Kinetics of Electrocatalytic Oxygen Reduction Reaction Over an Activated Glassy Carbon Electrode in an Alkaline Medium

Hydrogen peroxide is a promising substitute for fossil fuels because it produces non-hazardous by-products. In this work, a glassy carbon GC was anodized in sulphuric acid at +1.8 V to prepare the working electrode. It was utilized to investigate the oxygen reduction reaction (ORR) in a basic medium containing 0.1 M NaOH as a supporting electrolyte. The objective of this investigation was to synthesize hydrogen peroxide. X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), linear polarization, cyclic voltammetry (CV), and rotating disk electrode voltammetry (RDE) were performed for characterization and investigation of the catalytic properties. The RDE analysis confirmed that oxygen reduction reactions followed two electrons’ process at an activated GC electrode. Hence, the prepared electrode generated hydrogen peroxide from molecular oxygen at a potential of around −0.35 V vs. Ag/AgCl (sat. KCl), significantly lower than the pristine GC surface. The transfer coefficient, standard reduction potential, and standard rate constant were estimated to be 0.75, −0.27 V, and 9.5 × 10−3 cm s−1, resectively

Nitrogen and phosphorus co-doped carbocatalyst for efficient organic pollutant removal through persulfate-based advanced oxidation processes

Carbocatalysts doped with heteroatoms such as nitrogen or sulphur have been reported to be useful in persulfate-based advanced oxidation processes for organic pollutant removal. However, there is limited research on the effect of doping with phosphorus atoms on degradation performance. In this work, a new nitrogen and phosphorus-doped carbocatalyst (N, P-HC) was designed using hydrothermal carbonization followed by pyrolysis at 700 °C, with olive pomace as a carbon source, to degrade organic pollutants in the presence of peroxydisulfate (PDS). Experimental results showed that N, P-HC, with its large specific surface area (871.73 m2.g−1), high content of N-pyridinic and N-pyrrolic groups, and the presence of P-O-C and O-P-C bonds, exhibited high degradation performance (98% degradation of Rhodamine B (RhB) in 40 min, with an apparent rate constant (kapp) of 0.055 min−1 and an excellent turnover frequency (TOF) of 0.275 min−1). Quenching study and EPR analysis revealed that singlet oxygen generation (1O2) and direct electron transfer were the main reaction pathways for the non-radical pathway in the degradation of RhB. The improved catalytic efficiency in the N, P-HC/PDS/RhB system can be attributed to the synergistic effect between N and P atoms in the graphitic structure of the carbocatalyst, its high surface area, and the presence of oxygenated functional groups on the surface of the N, P-HC. The used N, P-HC carbocatalyst can also be efficiently recovered by heat treatment at 500 °C. Overall, this study presents a simple and environmentally friendly method for synthesizing a high-performance N, P co-doped olive pomace-based carbocatalyst for water decontamination through PS-AOPs processes

Exposure to heavy metals and neurocognitive function in adults: a systematic review

Abstract Exposure of individuals to heavy metals (HMs) is a growing concern with far-reaching implications for human health. HMs encompass a diverse range of elements that, when present in excess or in particular chemical forms, have the potential to elicit adverse effects on the central nervous system and cognitive function. This systematic review aims to comprehensively investigate the relationship between exposure to HMs and neurocognitive function in adults. The methodological framework for this review adheres rigorously to the Meta-analyses Of Observational Studies in Epidemiology (MOOSE) guidelines. A meticulous and extensive search strategy was executed within PubMed and Web of Science, specifically targeting articles published in the English language until the cutoff date of December 5, 2023. The evaluation of the retrieved studies was systematically conducted by employing the assessment approach outlined by (Gascon et al. in Environ Int 86 60 67, 2016). The initial search yielded a substantial pool of 1573 articles, culminating in a refined selection comprising eight pertinent studies, collectively enrolling a participant cohort totalling n = 1,828,126. Notably, the studies under review predominantly manifested a cross-sectional or cohort design and were geographically situated within the continents of North America and Asia. Furthermore, it is imperative to underscore that a predominant and recurring observation emanating from the majority of the scrutinized investigations underscores a significant correlation between exposure to cadmium (Cd) and mercury (Hg) and deleterious neurocognitive outcomes in the adult population. In summary, our systematic review postulates that exposure to HMs through various routes of exposure harbors the potential for adverse effects on adult neurocognitive function; however, it is incumbent upon future research endeavors to validate and corroborate these findings through further empirical exploration