International Journal of New Chemistry

14-29

Authors: Meaza Dejene; Kassim Kedir; Seblework mekonen; Abera Gure

In this study, the level of selected organophosphorus and organochlorine pesticide residues from water samples of Gilgle Gibe (I) hydroelectric dam reservoir and its potential tributaries, Jimma zone, Ethiopia, was determined by gas chromatography-electron capture detector (GC-ECD). Low density based dispersive liquid-liquid microextraction (LD-DLLME) using toluene (as extractant) and acetonitrile (as disperser) was used for extraction of pesticide residues from the samples. Calibration curves constructed at six concentration points have good linearity with coefficient of determination (r2) ranging from 0.995 - 0.999. The limits of detection (LOD) and quantification (LOQ) of the method which were determined as 3 and 10 times the signal-to-noise ratio were ranging from 0.0001 - 2.5810 µg/L and 0.0005 - 8.6050 µg/L, respectively. The efficiency of the method was also evaluated using recovery studies by spiking the water samples with known concentrations of the analytes. The obtained recoveries were ranging from 67 - 105% with relative standard deviations of 0.79 - 12.5%. The findings revealed that the studied water samples contain significant amount of the target pesticides, but endrin was not detected in any of the water sample. Methidathion was also detected only in Nada Qalla and Nada Gudda river water samples. The detected residual concentrations of the target pesticides were above the maximum residue limits, except DDT in acute toxic level. The finding indicated that the studied water samples contain considerable amount of the studied residual pesticides that can influence the health of aquatic organisms and other consumers.

47-59

Authors: Tesfa Bedassa; Medhanit Desalegne

In this paper, Qeera wastewater containing stream, found in Bakkee-Jamaa district of Nekemte town, was assessed for selected metals and physico-chemical properties. The metals were determined by flame atomic absorption spectrophotometry (FAAS). Additional water samples collected from Dangi spring water, which is found about 10 km far away from the town, and Chalalaqi waste water containing stream were also assessed for reference. Analysis of concentration of Pb, Cd, Cr, Ca, and Ni metals were carried out using FAAS. For metal analysis good linearity were obtained with coefficient of determination (R2) 0.998 or better. The LOD for the metals were in the range of 0.003 to 0.018 mg L−1 and LOQ, 0.010 to 0.06 mg L−1. Recovery studies ranged from 92 % to 104 % for the metals. The study shows that Ca, Cd and Ni are quantified in all the three water bodies. Overall, the level of the metals studied is higher in the urban area streams than that of Dangi spring in the rural area. The average concentrations (in mg/L) of Ca, Cd and Ni were found to be 9.56., 0.22 and 0.38, respectively. When compared with international guide lines for the quality of irrigation water, Cd and Ni are above permissible levels and show significant pollution of the water. The data obtained from the study of selected physico-chemical properties (EC, TDS, pH, TSS and Cl¯) of the water samples were found to be within the recommended level except TSS.

74-86

Authors: Sheila Kumer; Maryam Ebrahimikia; Mohammad Yari

In this study 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) interaction with carbon nanocone(NC) and nanocone Sheet (NCS) was evaluated by density functional theory. The calculated thermodynamic parameters including Gibbs free energy changes and Enthalpy alterations showed the interaction of TATB with the both nanostructures are exothermic, spontaneous, experimentally possible and irreversible. The specific heat capacity values proved the heat sensitivity of TATB decline after its adsorption on the surface of carbon nanocone and nanocone sheet. The effect of temperature on this process was also investigated and the results indicated 300 K is the optimum temperature for the interaction of TATB with the nanostructures. The frontier molecular orbital analysis was also employed and the findings indicated the reactivity and energetic traits of TATB have enhanced significantly after its interaction with carbon nanocone and nanocone sheet. Indeed, both of the nanostructures cause a substantial improvement in energetic features and a tangible decrease in the heat sensitivity.