Cellulose acetate-Sn(IV) molybdophosphate: A biopolymer supported composite Exchanger for the removal of selected heavy metal ions

Cellulose acetate-tin(IV) molybdophosphate (CATMP) composite exchanger was prepared by mixing biopolymer celluloseacetate with its inorganic counterpart tin(IV) molybdophosphate (TMP) using sol‑gel method. The physical characterization of the as synthesized exchanger was carried out by FTIR, XRD, BET, TGA-DTG and SEM-EDX techniques. Chemical properties such as ion exchange capacity, chemical stability, pH and distribution behavior were carried out. The average IEC of the composite material, as determined by batch equilibrium, was found to be 2.43 meq/g for Na+ ion; higher than its inorganic counterpart, i.e. 1.41 meq/g. This exchanger was also found to be stable in water, acids and organic solvents, but unstable in basic medium. The distribution study (Kd) of the exchanger in different solvent systems showed promising separation potential of the exchanger towards metal ions of analytical interest from a given mixture of toxic heavy metal ions. The sorption studies revealed that the material was selective for Cr(III) and Cd(II) ions and moderately selective for Co(II) ion in solvents employed in this work. Its selectivity was examined by achieving some important binary separations of metal cations on its column indicating its promising application in environmental pollution abatement.                     KEY WORDS: Cation exchanger, Biopolymer, Organic-inorganic hybrid, Sol–gel method, Binary distribution   Bull. Chem. Soc. Ethiop. 2020, 34(2), 259-276 DOI: https://dx.doi.org/10.4314/bcse.v34i2.

Lead accumulation in the roadside soils from heavy density motor way towns of eastern Ethiopia

The levels of lead pollution in the roadside soils of the heavy density motor ways of Eastern Ethiopia, in particular; Modjo, Bishoftu and Adama towns were studied. Soil samples were collected from a total of 22 sampling sites while the control samples were obtained from places about 1 km away from the main roads of each town. Concentrations of lead, in soil samples, were determined using flame atomic absorption spectrometer and the average concentrations of lead were found to be 93.3 ± 1.0, 79.4 ± 0.6 and 80.6 ± 0.4 μg/g for Modjo, Bishoftu and Adama towns, respectively. The concentrations of lead in soils sampled 1 km away from the main road for each town were: 13.5 ± 0.3, 19.6 ± 0.7 and 20.8 ± 0.8 μg/g for Modjo, Bishoftu and Adama towns, respectively. The contamination factors for the average lead concentrations of Modjo, Bishoftu and Adama towns were 6.9, 4.0 and 3.8, respectively. Besides, the correlations between the lead level and the traffic density of the corresponding roads were found to be r (4) = 0.82, p < 0.05 for Modjo, r (5) = 0.32, p < 0.05 for Bishoftu and r (9) = 0.81, p < 0.05 for Adama. KEY WORDS: Gasoline, Lead, Roadside soils, Traffic density, Vehicular emission, Ethiopia Bull. Chem. Soc. Ethiop. 2014, 28(2), 161-176.DOI: http://dx.doi.org/10.4314/bcse.v28i2.

Preparation and Adsorption Behavior of Ce(III)-MOF for Phosphate and Fluoride Ion Removal from Aqueous Solutions

The discharge of inorganic pollutants like phosphate and fluoride is a cause of mounting concern to the world due to the substantial environmental and human health risk. Adsorption is one of the most common and affordable technologies widely utilized for removing inorganic pollutants such as phosphate and fluoride anions. Investigating efficient sorbents for the adsorption of these pollutants is extremely important and challenging. This work aimed at studying the adsorption efficiency of the Ce(III)-BDC metal-organic framework (MOF) for the removal of these anions from an aqueous solution using a batch mode. Powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDX) techniques evidenced the successful synthesis of Ce(III)-BDC MOF in water as a solvent without any energy input within a short reaction time. The outstanding removal efficiency of phosphate and fluoride was exhibited at an optimized pH (3, 4), adsorbent dose (0.20, 0.35 g), contact time (3, 6 h), agitation speed (120, 100 rpm), and concentration (10, 15 ppm) for each ion, respectively. The experiment on the effect of coexisting ions demonstrated that SO42- and PO43- ions are the primary interfering ions in phosphate and fluoride adsorption, respectively, while the HCO3- and Cl- ions were found to have interfered less. Furthermore, the isotherm experiment showed that the equilibrium data fitted well with the Langmuir isotherm model and the kinetic data correlated well with the pseudo-second-order model for both ions. The results of thermodynamic parameters such as ΔH°, ΔG°, and ΔS° evidenced an endothermic and spontaneous process. The regeneration of the adsorbent made using water and NaOH solution showed the easy regeneration of the sorbent Ce(III)-BDC MOF, which can be reused four times, revealing its potential application for the removal of these anions from aqueous environment. © 2023 The Authors. Published by American Chemical Society.The authors acknowledge the research grant obtained from Haramaya University (HURG-2016-03-02 and HURG-2020-03-02-75). The authors also acknowledge the Spanish Research Council, CSIC, for funding through the project i-COOP+2018 (COOPA20271). The authors are also indebted to the Institute of Catalysis and Petroleum Chemistry (ICP), Spain, Addis Ababa University and Adama Science and Technology University, for the support afforded to characterize the as-synthesized Ce-MOFs.Supporting InformationPeer reviewe

Generalized cure rate model for infectious diseases with possible co-infections

Abstract This research mainly aims to develop a generalized cure rate model, estimate the proportion of cured patients and their survival rate, and identify the risk factors associated with infectious diseases. The generalized cure rate model is based on bounded cumulative hazard function, which is a non-mixture model, and is developed using a two-parameter Weibull distribution as the baseline distribution, to estimate the cure rate using maximum likelihood method and real data with R and STATA software. The results showed that the cure rate of tuberculosis (TB) patients was 26.3%, which was higher than that of TB patients coinfected with human immunodeficiency virus (HIV; 23.1%). The non-parametric median survival time of TB patients was 51 months, while that of TB patients co-infected with HIV was 33 months. Moreover, no risk factors were associated with TB patients co-infected with HIV, while age was a significant risk factor for TB patients among the suspected risk factors considered. Furthermore, the bounded cumulative hazard function was extended to accommodate infectious diseases with co-infections by deriving an appropriate probability density function, determining the distribution, and using real data. Governments and related health authorities are also encouraged to take appropriate actions to combat infectious diseases with possible co-infections