This study reports on the adsorption of Hexavalent Chromium from aqueous solutions using activated carbon prepared from bamboo (Oxytenanthera abyssinica) waste by KOH activation heating in an electrical furnace at 1073 K for 3 hrs. Batch adsorption experiments were also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage, and temperature of the solution. Kinetic studies of the data showed that the adsorption follows the pseudo-second-order kinetic model. Thermodynamic parameters showed that adsorption on the surface of BWAC was feasible, spontaneous in nature, and exothermic between temperatures of 298 and 318 K. The equilibrium data better fitted the Freundlich isotherm model for studying the adsorption behavior of Hexavalent Chromium by BWAC. IR spectrum for loaded and unloaded BWAC was obtained using FT-IR spectrophotometer. Adsorption efficiency and capacity of Hexavalent Chromium were found to be 98.28% at pH 2 and 59.23 mg/g at 300 K.

Ethiopian traditional alcoholic beverages namely tella, tej and areki are very common drinks in the country. Ten (10) alcohol vending houses were considered in the study by considering two from each five sub-cities, purposely for 'filtered' tella sampling and five for the unfiltered tella, tej and areki samples. The alcoholic contents of filter-tella, tej and areki were measured and found in the range of 3.84 to 6.48, 8.94 to 13.16 and 33.95 to 39.9% v/v ethanol, respectively. Difference in pH values and ethanol levels among all samples was significant (p<0.05). Variations within samples of each vending houses, coefficient of variation (CV>10%) among all samples were significant, though the variation in pH of the alcohols studied were analyzed and found at drinking range or according to European Brewery Convention. Finally, sensory responses which were taken from the community (people drinking these alcohols), indicated that they are high in aroma (bitterness for tella than other drinks reported).

This study reports on the adsorption of 2-chlorophenol from an aqueous solution using activated carbon prepared by H 2 SO 4 activation of the pericarp of Ricinus communis (RCAC). The pericarp was carbonized and activated by treating with H 2 SO 4 solution followed by heating in an oven at 105°C for 12 hrs. Batch adsorption experiments were carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature of the solution. Kinetic data were best fit to a pseudo-first-order rate equation for the adsorption of 2-chlorophenol on RCAC. Thermodynamic parameters ΔH o , ΔS o and ΔG o for the adsorption were also determined which shows that adsorption on the surface of RCAC was spontaneous in nature, and exothermic between temperatures of 20°C and 80°C. The equilibrium data better fit the Langmuir isotherm model for 2-chlorophenol adsorption on RCAC. IR spectrum for loaded and unloaded RCAC was obtained and found to be in good agreement. ARTICLE HISTORY

Polyaniline (PANI) in its emeraldine salt form was synthesized by chemical method from aniline monomer in the presence of HCl mixed with LiCl and ammonium persulfate as oxidant. Then, a portion of sample was dedoped with NH 3 solution and another equal portion was separately postdoped with secondary dopants, such as H 2 SO 4 and HClO 4 , respectively. Finally, the dried samples of PANI prepared in all its three different forms (emeraldine salt form, undoped emeraldine base, and the two secondary doped forms of PANI) were characterized by UV-visible spectroscopy, cyclic voltammetry (CV) techniques, Fourier transform infrared (FT-IR) spectroscopy, and electrical conductivity measurement. The cyclic voltammograms of PANI in its emeraldine base (PANI-EB) determined the electrochemical behavior and the growth mechanisms of the polymer. The FT-IR and UVvis spectra confirmed the expected structural modification up on doping, undoping, and postdoping processes of the polymer. Their measured electrical conductivities were from 0.02 for undoped, 156 for primary doped form, and increasing from 158 to 257 S/cm for those secondary doped PANI. The influence of secondary doping on the electrical conductivity was also investigated from their spectroscopic data which shows dramatic rise in conductivity. The result also shows that secondary doping increased the π conjugation.

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Present study discusses the removal of heavy metal contaminants from an aqueous solution using orthophosphoric acid activated pumpkin seed shells derived activated carbon (PSS-AC). The activation was done by heating the mixture in an electrical furnace at 800 °C for 3 h. Adsorption experiments were carried out as a function of pH, contact time, initial Cu (II) and Cd (II) ion concentrations, adsorbent dosage and temperature of the solution for the metal ion removal. The equilibrium and kinetic studies data were fitted better for the Langmuir isotherm model and pseudo-second order model respectively. Thermodynamic parameter obtained for Cu (II) and Cd (II) ions adsorption suggests the reaction to be non-spontaneous, feasible; and endothermic between temperatures of 25 °C and 45 °C.