Chemically Activated Carbon Based on Biomass for Adsorption of Fe(III) and Mn(II) Ions from Aqueous Solution.

Rice husk was converted into activated carbon (AC) as a byproduct of agricultural waste in an electric furnace at 700 °C and chemically activated using three distinct processes: NaOH AC(C), acetic acid AC(C-1), phosphoric acid AC(C-2), and carbonization AC(C-3) without any chemical activation. To characterize the activated carbon and the removal efficiencies of Fe(III) and Mn(II) from aqueous solutions, various analytical tools were used. The results revealed that the capacities of the four adsorbents to adsorb Fe(III) or Mn(II) from an aqueous solution differ significantly. AC(C-3) was chosen for additional research. The impact of different operational factors, including pH, contact time, adsorbent dosage, starting metal ion concentration, interfering ions, and temperature, were investigated. The optimum pH values for Fe(III) and Mn(II) adsorption were found to be pH 3 and pH 6, respectively. The results obtained were utilized to assess the kinetics and thermodynamics of the adsorption process. The sorption of Fe(III) and Mn(II) ions was found to be a pseudo-second-order kinetic process, and the equilibrium data were fitted with the Langmuir isotherm. Additionally, the evidence suggests that an endothermic mechanism governs the adsorption process. The maximum adsorption capacities of Fe(III) and Mn(II) were 28.9 and 73.47 mg/g, respectively.

Menstrual changes after COVID-19 vaccination and/or SARS-CoV-2 infection and their demographic, mood, and lifestyle determinants in Arab women of childbearing age, 2021.

Background: By September 2, 2021, over 30,000 COVID-19-vaccinated females had reported menstrual changes to the MHRA's Yellow Card surveillance system. As a result, the National Institutes of Health (NIH) is urging researchers to investigate the COVID-19 vaccine's effects on menstruation. Therefore, this study was conducted to explore the menstrual changes after COVID-19 vaccination and/or SARS-CoV-2 infection and their interrelations with demographic, mood, and lifestyle factors in Arab women of childbearing age (CBA). Methodology: A cross-sectional study was conducted during October 2021 using an Arabic validated and self-administrated questionnaire. In total, 1,254 Women of CBA in the Arabic Population (15-50 y) with regular menstrual cycles were randomly selected from five countries (Saudi Arabia, Egypt, Syria, Libya, and Sudan). Results: The mean (SD) age of the 1,254 studied females was 29.6 (8.5) years old. In total, 634 (50%) were married, 1,104 (88.0%) had a University education or above, 1,064 (84.4%) lived in urban areas, and 573 (45.7%) had normal body weight. Moreover, 524 (41.8%) were COVID-19 cases and 98 women (18.7%) reported menstrual changes (MCs). The 1,044 (83.5%) vaccinated females reported 418 (38.5%) MCs after being vaccinated, and these MCs resolved in 194 women (55.1%) after more than 9 months. Statistically significant relationships were observed between the reported MCs and the following variables: age, marital status, level of education, nationality, residence, and BMI. MCs were reported at 293(80.6) after the 2nd dose, and were mainly reported after 482 (46.1) Pfizer, 254 (24.3) Astrazenica, and 92 (8.8) Senopharm. Conclusion: MCs among women of CBA after COVID-19 infection and vaccination are prevalent and complex problems, and had many determinates.

Tuning the structural and catalytic properties of copper(II)-based complexes containing pyridine-2,6-diimines.

Four mononuclear penta coordinated copper(II) chelates, [CuLnBr2] nH2O, containing the tridentate neutral ligands, pyridine-2,6-diimine (Ln), were prepared via the template technique. Analytical and several physicochemical methods have been used to characterize the prepared metal chelates. Square-pyramidal stereochemistry was described to the current copper(II) complexes. DFT technique has been applied to optimize the structure of the running diimines and their corresponding copper-based compounds. Ligand substitution study performed to link the catalytic potency of the candidate oxidase mimics and their lability characters. Spectral investigations reveal that nature of substituents of the chelated ligands effectively tuning the Lewis acidity of copper(II) centers. Biomimetics of redox proteins specifically containing copper were examined towards the aerobic oxidation of polyphenol. Kinetic studies with the stopped-follow technique showed a close association between the Lewis acidity of the copper(II) nuclei of the prepared chelates and their oxidase-like activity. The catalytic activity of the natural enzyme (catechol oxidase from sweet potatoes) measured and compared with that for the present CuII chelates. The thermodynamic parameter drive force (ΔG° or λ) of the performed oxidation processes was determined from the values of redox potential of the chemical species involved in these catalytic reactions. The proposed catalytic reactions pathways have been discussed based on the outcomes of the kinetic investigations.Communicated by Ramaswamy H. Sarma.

Nitrogen Graphene: A New and Exciting Generation of Visible Light Driven Photocatalyst and Energy Storage Application.

The synthesis of nitrogen, boron, and nitrogen-boron-codoped graphenes was attained via mixing solutions of GO with urea, boric acid, and a mixture of both, respectively, followed by drying in vacuum and annealing at 900 °C for 10 h. These materials were thoroughly characterized employing XRD, TEM, FTIR, Raman, UV-vis, XPS, IPCE%, and electrical conductivity measurements. The nitrogen-doped graphene (NG) showed an excellent supercapacitor performance with a higher specific capacitance (388 F·g-1 at 1 A·g-1), superior stability, and a higher power density of 0.260 kW kg-1. This was mainly due to the designated N types of doping and most importantly N-O bonds and to lowering charge transfer and equivalent series resistances. The NG also indicated the highest photocatalytic performance for methylene blue (MB 20 ppm, power = 160 W, λ > 420 nm) and phenol (5 ppm) degradation under visible light illumination with rate constants equal 0.013 min-1 and 0.04 min-1, respectively. The photodegradation mechanism was proposed via determining the energy band potentials using the Mott-Schottky measurements. This determined that photoactivity enhancement of the NG is accounted for by acquisition of nitrogen-oxy-carbide phases that shared in inducing a higher IPCE% (60%) and a lower band gap value (1.68 eV) compared to boron and nitrogen-boron-codoped graphenes. The achieved photodegradation mechanism relied on scavengers performance suggesting that •OH and electrons were the main reactive species responsible for the MB photodegradation.