DETERMINATION OF THE LEVELS OF LEAD IN THE ROADSIDE SOILS OF ADDIS ABABA, ETHIOPIA

Contamination of the roadside soils of Addis Ababa city by lead, most likely originationg from vehicular exhaust, has been investigated. To this end, soil samples were collected from 14 roadside sites; i.e., 2 samples for shorter and 5 samples for longer roads. Determination of lead was carried out on a total of 45 samples and a control sample collected from a relatively remote area of the city, Entoto Mountains, which was assumed to be free of anthropogenic lead sources. The levels of lead in all the samples were determined using flame atomic absorption spectrometer. The concentration of lead obtained from majority of the sample sites surpassed the maximum limit of the metal in soil recommended by WHO (100 μg/g). The average concentrations of lead in the roadside soils were found to be 418.6 ± 3.4 μg/g. Similarly, the concentration of lead in the control soil sample was 18.8 ± 0.5 μg/g. Although at present the lead content of the gasoline used in the country is 0.013 g/L, the use of leaded gasoline during the past decades is thought to be responsible for the high concentration of lead in the roadside soils of Addis Ababa

Al2O3/Fe3O4/ZrO2 ternary oxide sorbent: Synthesis, characterization and sorption behavior to fluoride and phosphate ions from aqueous solution

ABSTRACT. Excess quantities of fluoride and phosphate in water bodies can lead to fluorosis and eutrophication problems, respectively. In search of a promising adsorbent targeting these ions, Fe3O4/Al2O3/ZrO2 ternary oxide was synthesized via co-precipitation method and characterized by X-ray diffraction (XRD), Fourier transform-infrared (FTIR) and Brunauer-Emmer-Teller (BET). Its specific surface area was found to be 205 m2/g. The effects of solution pH, adsorbent dose, contact time, agitation speed and initial fluoride and phosphate concentrations were also investigated and the optimum values were 4, 0.5 g, 12 h, 100 rpm and 20 mg/L, respectively, for fluoride and 5, 0.1 g, 8 h, 100 rpm and 10 mg/L, respectively, for phosphate. Fluoride and phosphate adsorptions fitted well with Freundlich and Langmuir isotherm models, respectively and their kinetic data correlated well with the pseudo-second order model. Desorbability study revealed that maximum desorption was achieved at pH 12. Thermodynamics study on the other hand showed that adsorption of fluoride was nonspontaneous and endothermic whereas that of phosphate was spontaneous and exothermic. Application on real water sample decreased the concentration of fluoride from 4.92 to 1.97 mg/L in ground water and phosphate from 1.7 to 0.35 mg/L lake water showing its potential as a promising adsorbent.   KEY WORDS: Adsorption, Fluoride, Phosphate, Ternary oxide sorbent, Isotherm models   Bull. Chem. Soc. Ethiop. 2022, 36(3), 555-569.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i3.6                                                         &nbsp

Preparation and sorption property study of Fe3O4/Al2O3/ZrO2 composite for the removal of cadmium, lead and chromium ions from aqueous solutions

Fe-Al-Zr ternary mixed oxides composite was synthesized via co-precipitation method for the removal Pb(II), Cd(II) and Cr(VI) ions from aqueous solutions. The as-synthesized materials were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope hyphenated with energy dispersive X-ray diffraction (SEM-EDX) and Fourier transform infrared (FTIR) techniques. The pH at the point of zero charge (pHpzc) of the sorbent and effect of ionic strength on sorption were also determined. The batch tests were conducted to optimize the various sorption parameters such as pH, adsorbent dose, contact time, speed of agitation and initial metal concentration. The experimental results showed that the adsorbed amounts of Pb(II), Cd(II) and Cr(VI) tend to decrease with increase in pH. Freundlich isotherm model fits better the equilibrium data for the adsorbent. Kinetic data correlated better with both pseudo first order and pseudo second order kinetic models. The spontaneous nature of the adsorption process was also confirmed from thermodynamic grounds. The nanosized adsorbent exhibited an adsorption efficiency of 96.65%, 96.55% and 97.2% for Cd(II), Cr(VI) and Pb(II), respectively, at optimum condition. Experimental results showed that the nanocomposite was effective for the removal of the title heavy metals from aqueous solution.   Bull. Chem. Soc. Ethiop. 2020, 34(1), 105-121. DOI: https://dx.doi.org/10.4314/bcse.v34i1.1

The non-edible and disposable parts of oyster mushroom, as novel adsorbent for quantitative removal of atrazine and its degradation products from synthetic wastewater

In this study, the non-edible part of oyster mushroom was utilized for quantitative removal of the most commonly used s-triazine herbicide; atrazine and its breakdown products including deethylatrazine (DEA), hydroxyatrazine (ATOH) and deisopropylatrazine (DIA) from aqueous samples. The functional groups available on the oyster mushroom were studied applying FTIR before and after adsorption. Experimental parameters influencing the uptake process including acidity, sorbent mass, sorption time, initial analyte quantities, and agitation speed were analysed and the maximum removal was found at 4, 0.3 g, 120 min, 0.5 mg L−1, and 150 rpm, respectively. Accordingly, the adsorption capacities of 0.994, 1.113, 0.991 and 1.016 mg g−1 were obtained for DIA, DEA, ATOH and atrazine, respectively. The adsorption characteristics were discussed utilizing Langmuir and Freundlich isotherm models. The fundamental characteristic of the Langmuir isotherm, which can be elaborated using separation factor or equilibrium parameter, RL, and coefficient of variation, R2, were (0.761, 0.996), (0.884, 0.975), (0.908, 0.983) and (0.799, 0.984) for DIA, DEA, ATOH and Atrazine, respectively. These findings showed that all analytes' adsorption processes were fitted well to the Langmuir adsorption isotherm, indicating that the adsorbent surface was covered in a monolayer. The kinetics was also evaluated using the pseudo-first and pseudo-second order models. The coefficient of determination, r2, were found to be 0.09703, 0.9989, 0.9967 and 0.9998 for DIA DEA, ATOH and atrazine, respectively, for pseudo-second order, signifying that, all analytes were found to follow the pseudo-second order rate model showing that the rate limiting step is chemisorption in the sorption process. Based on these findings, the non-edible and disposable part of the oyster mushrooms can be utilized as a preferred alternative biosorbent for the uptake of the target compounds analysed and other pollutants possessing comparable physicochemical characteristics occurring in various water bodies

Impact of source water quality on total organic carbon and trihalomethane removal efficiency in a water treatment plant: A case study of Upper Awash, Ethiopia

This study addresses the limited understanding of factors affecting the efficiency of water treatment plants in reducing trihalomethane (THM) formation through total organic carbon (TOC) removal, highlighting significant challenges in improving treatment effectiveness. The aim of this study was to examine the influence of water quality on the efficiency of water treatment plants to remove TOC and reduce THM formation. Linear regression and correlation analyses were conducted to examine the relationship between water quality parameters and THM concentrations. The results showed that there was a negative relationship between turbidity, metals, and TOC concentration with TOC removal efficiency. Positive correlations were found between parameters and the formation of THMs in water. Of these parameters, water temperature was observed to have relatively less influence on THM formation. It was observed that seasonal variations in water quality affect the efficiency of TOC removal and THM content in treated water. THM levels in chlorinated water were found to be within the permissible range of the World Health Organization's drinking water quality guidelines. However, it is still important to maintain continuous monitoring and take measures to reduce THMs. The model demonstrated a strong correlation (R2 = 0.906) between predicted and measured THM values. HIGHLIGHTS The variability of water sources’ qualities such as turbidity, water temperature, metallic concentration, and total organic carbon strongly affects the performance of the water treatment plant in removing total organic carbon, and this leads to an increase in trihalomethane formation and variation in chlorinated drinking water supply.; The model developed from the analysis of water quality parameters accurately predicts the variation and formation of THMs (trihalomethanes) in drinking water.

Fe-Al-Mn ternary oxide nanosorbent: Synthesis, characterization and phosphate sorption property

In the present work, nanocrystalline Fe-Al-Mn ternary oxide nanosorbent was synthesized via impregnation method. X-ray diffraction (XRD), scanning electron microscope coupled with energy dispersive x-ray spectroscopy (SEM/EDX), Brunauer–Emmett–Teller (BET) technique and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the as-synthesized nanomaterials. The XRD result indicates the crystalline nature of the ternary oxide with BET surface area of 49.53 m2 g−1. The optimum operating conditions to carry out sorption study such as pH, adsorbent dose, contact time, speed of agitation and initial phosphate concentration were found to be 3, 0.1 g, 16 h, 100 rpm and 30 ppm, respectively. Both Freundlich and Langmuir isotherm models fit the equilibrium data well with the latter model providing more fit to the experimental data. Kinetic data correlated well with the pseudo-second-order and Elovich models suggesting chemisorptions as the prevailing mechanism of phosphate sorption onto the nanosorbent. Thermodynamic studies resulted negative ΔG values indicating the spontaneity of the sorption process. The Fe-Al-Mn ternary nanocomposite sorbent showed a sorption capacity of 38.46 mg g−1 at pH 3. The sorption efficiency of the nanosorbent was found to be 99.5%. This adsorbent, with large sorption capacity and efficiency, is therefore a promising adsorbent for the removal of phosphate ions from aqueous systems.ID is grateful to CSIC for her research leave at AAU and HU. The financial support from the Spanish Research Council CSIC I-COOP+-2014 (COOPB20082) is acknowledged for funding. This work has also been funded from Projects MAT2015-65767-P (MINECO) and MAT2016-77496-R (AEI/FEDER, UE). The Research and Extension Office of Haramaya University (HURG-2014-03-03), School of Graduate Studies and Chemistry Department of HU are also acknowledged.Peer reviewe

First-line antiretroviral treatment failure and associated factors in HIV patients at University of Gondar Teaching Hospital, Gondar, Northwest Ethiopia

Mohammed Biset Ayalew,1 Dawit Kumilachew,2 Assefa Belay,3 Samson Getu,4 Derso Teju,4 Desalegn Endale,4 Yemisirach Tsegaye,4 Zebiba Wale4 1Department of Clinical Pharmacy, 2Department of Pharmaceutics, 3Department of Pharmacology, 4School of Pharmacy, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia Background: Antiretroviral therapy (ART) restores immune function and reduces HIV-related adverse outcomes. But treatment failure erodes this advantage and leads to an increased morbidity and compromised quality of life in HIV patients. The aim of this study was to determine the prevalence and factors associated with first-line ART failure in HIV patients at the University of Gondar Teaching Hospital.Patients and methods: A retrospective study was conducted on 340 adults who had started ART during the period of September 2011 to May 2015. Data regarding patients’ sociodemographics, baseline characteristics, and treatment-related information were collected through review of their medical charts. Data were analyzed using SPSS version 21. Descriptive statistics, cross-tabs, and binary and multiple logistic regressions were utilized. P<0.05 was used to declare association.Results: Among the 340 patients enrolled, 205 were females (60.3%). The mean age at ART initiation was 34.4 years. A total of 14 (4.1%) patients were found to have treatment failure. The median duration of treatment failure from initiation of treatment was 17.5 months (8–36 months). Poor adherence to treatment and low baseline CD4 cell count were found to be significant predictors of treatment failure.Conclusion: The prevalence of first-line ART failure was 4.1%. Treatment failure was most likely to occur for the patients who had poor drug adherence and those who were delayed to start ART till their CD4 cell count became very low (<100 cells/mm3). Keywords: treatment failure, antiretroviral drugs, risk factor, adherenc