Polypyrrole–polyaniline-water hyacinth leaf protein concentrate composite for the removal of Cr(VI) from aqueous solution: kinetics, isotherm and thermodynamic studies

ABSTRACT. This work focused on the extraction of “water hyacinth leaf protein concentrate” (WHLPC) and preparation of polypyrrole (PPy), polyaniline (PANI) and polypyrrole-polyaniline copolymer (PPy/PANI) coated WHLPC by in situ polymerization and investigate their application for the removal of Cr(VI) from aqueous solution. After optimizing the experimental conditions like pH, adsorbent dosage, contact time and initial concentration it was found that the kinetics and isotherm data were well fitted to the pseudo-second-order and Langmuir models, respectively. PPy/PANI/WHLPC was found to be an efficient material compared to the other polymer-coated adsorbents with maximum adsorption capacity of 230 mg/g. The presence of counter ions ((NO3-, Cl-, HPO42-, SO42+ and HCO3- ions) slightly decreases the Cr(VI) removal efficiency PPy/PANI/WHLPC. The thermodynamic study reveals that the adsorption of Cr(VI) onto PPY/PANI/WHLPC is endothermic, thermodynamically feasible, and spontaneous. In addition, reusability of the material indicated high removal efficiency for two adsorption cycles.   KEY WORDS: Polypyrrole, Polyaniline, Protein concentrate, Water hyacinth, Chromium Bull. Chem. Soc. Ethiop. 2022, 36(3), 571-584.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i3.

Quantification of lead in cooking utensils and vegetables using square wave anodic stripping voltammetry

A simple and sensitive voltammetric method using in-situ bismuth film modified glassy carbon electrode (BiFGE) and Nafion-coated bismuth film modified glassy carbon electrode (NC-BiFGE) were used to determine the amount of lead(II) present in locally produced (at Kombolcha, 376 km North of Addis Ababa, Ethiopia) and imported cooking utensils and vegetable samples before and after cooking with the utensils. The voltammetric method was validated using standard spectroscopic method and recovery tests. The amount of lead(II) found in the locally produced utensil (6.48 mg L−1) was very high compared to the imported utensil (0.007 mg L−1). Moreover, a 3–5 fold increase in the amount of lead(II) was found when different vegetables were cooked with the local utensil as a result of the leaching out of the lead(II) from the cooking utensil

Voltammetric Determination of Paracetamol with Poly(3,4-Ethylenedioxythiophene) Modified Glassy Carbon Electrode Analytical & Bioanalytical Electrochemistry

Abstract-This study describes the preparation and application of a poly(3,4-ethylenedioxythiophene) (PEDOT) modified glassy carbon electrode for paracetamol determination in pharmaceutical samples. The PEDOT modified electrode was prepared by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) on a glassy carbon electrode in a non-aqueous medium. The best performance of the PEDOT modified electrode in 0. , respectively. Finally, the proposed method was applied for paracetamol determination in commercial tablets with a mean recovery of (1016) %

Electrochemical Sensor for Determination of Fenitrothion at Multi-wall Carbon Nanotubes Modified Glassy Carbon Electrode

A sensor, based on multi-wall carbon nanotubes modified glassy carbon electrode (MWCNT/GCE), was developed for determination of fenitrothion. Determining the surface area of MWCNT/GCE showed that this surface is three times more active than that of a glassy carbon electrode. The experimental parameters, such as the amount of MWCNTs, pH of the fenitrothion solution, preconcentration potential and preconcentration time were optimized. Under these conditions, reduction current showed a linear relationship with the concentration of fenitrothion in a range of 0.01-5.0 mM, with a detection limit of 6.4 nM. The modified electrode also exhibited good stability and reproducibility. The effects of possible interferents were studied and found to be negligible, indicative of high selectivity of the electrode. This sensor was also successfully employed for determination of fenitrothion in soil and Teff samples with recovery values in the range of 88.0-93.3% and 86.7-91.4%, respectively

Stripping voltammetric determination of pyridine-2-aldoxime methochloride at iron (III) doped zeolite modified glassy carbon electrode

Trabajo presentado en el 4th Federation of African Chemical Societies (FASC) congress, celebrado en Marrakech (Marruecos) del 7 al 9 de mayo de 2013.An iron(III) doped zeolite modified glassy carbon electrode was constructed for the determination of pyridine-2-aldoxime methochloride. X-ray diffraction and chemical analysis were utilized to determine the optimum pH and chemical content for doping zeolite. Cyclic voltammetry was used to characterize the modified electrode and study the kinetics of the acid treated and untreated modified electrode. Acid treatment of the modified electrode showed a better electrochemical behavior compared to the untreated iron(III) doped zeolite modified electrode. Square wave anodic stripping voltammetry was employed to investigate the working pH and preconcentration time. The analytical performance of the modified electrode was evaluated, and a linear anodic stripping response for pyridine-2-aldoxime methochloride in the concentration range of 0.5–100.0 μM with a detection limit of 1.61 × 10−7 M was obtained. Finally, the developed method was successfully applied for the determination of pyridine-2-aldoxime methochloride in a biological sample.Peer Reviewe

Utilization of dual contraception method among reproductive age women on antiretroviral therapy in selected public hospitals of Northern Ethiopia

Abstract Background Sexually transmitted infections are highly prevalent among pregnant women in Africa. Among the incidence of HIV infection in children, 90% of the infection is attributable to their mothers. Ethiopia is one of the countries with an increasing risky sexual behavior and the most affected by the HIV epidemic. If prevention of mother to child transmission focuses on increasing contraception, it will prevent more than 29% of HIV infection at birth. Therefore, the aim of this study was to assess utilization of dual contraceptive  method and associated factors among reproductive age women on antiretroviral therapy in selected public hospitals of Mekelle town, Northern Ethiopia. Methods Institution based cross-sectional survey was conducted in selected public hospitals of Mekelle among women under antiretroviral therapy from March 1–April 31, 2016. We used a systematic sampling technique to select 331 women. A pretested interviewer administered questionnaire was used for data collection. The data were entered in to Epi data version 3.1 and exported to SPSS version 20 for analysis. Bivariate and multivariable logistic regression analysis was computed. Odds ratio along with 95% CI was computed to ascertain the association. Statistical tests at p-value of < 0.05 were considered as cut off point to determine statistical significance. Results Only 51(15.7%) of participants have utilized dual contraception method. Being single[AOR 5.43, 95% CI (1.61, 18.32)] and cohabitated [AOR 6.06; 95% CI: (2.16, 16.95)] in marital status, having HIV negative partner [AOR 4.44; 95% CI: (1.23, 16.04)], exposure to post diagnosis counseling [AOR 3.03; 95% CI: 1.34, 6.80], disclosed HIV status [AOR 6.06; 95% CI: (1.78, 20.87)] and discussing safer sex with partner [AOR 6.96; 95% CI: (2.75, 16.62)] were positively associated with utilization of dual contraceptive method. Conclusion The overall magnitude of dual contraceptive use is still low in this study. This will be a great concern on the transmission of the virus from mother to babies and partners and risk of complications following unintended pregnancy. This will continue to present as major public health problems in the region unless future interventions focuses on the barriers through tailored counseling and husband involvement in all aspects of the HIV/AIDS care