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  • Author or Editor: M. Chaudhry x
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Abstract  

The sorption of chromium(III) onto Haro river sand has been investigated as a function of sorptive solution composition, amounts of sorbent (10–500 mg) and sorbate (4.33·10−8–5.17·10−6 M), shaking time (I-60 minutes) and temperature (15–35°C). Maximum sorption has been achieved from 0.001 M HCI solution using 50 mg of the sand and 20 minutes shaking time. The sorption data followed Freundlich and D-R isotherms. The sorption capacity of 0.4 μmole·g−1 and of sorption energy of 9.9 kJ·mole−1 have been computed from D-R parameters. Thermodynamic parameters ΔH=84.4 kJ·mole−1, ΔS=284.5 J·mole−1·K−1 and ΔG=−3.32 kJ·mole−1 at 298 K have been evaluated. Fe(II), Al(III), citrate, borate, oxalate, tartrate and carbonate ions reduce the sorption significantly. Under similar experimental conditions Tc(VII), Re(VII), Sb(V) and Co(II) have very low sorption (<1%) and trivalent Eu and Sm have large distribution ratios. Haro river sand can be used to preconcentrate or to remove micro or submicro amounts of Cr(III) from very dilute solution and for the separation of Tc, Re and Sb from Cr, Eu and Sm.

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Abstract  

An instrumental neutron activation analysis method based on the measurement of239Np has been developed for the determination of uranium in ores. The samples after 5 sec irradiation were cooled for 3 days and the gamma-ray spectra were measured with a 30 cm3 Ge(Li) detector. The precision and accuracy of the proposed method were determined by analysing IAEA Standard Uranium Ore samples.

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Abstract  

The concentration of 15 elements in various brands of cigarette tobacco and cigarette wrapping paper were determined using instrumental neutron activation analysis. The paper of some of the brands contains higher concentrations of toxic elements than the tobacco. The cigarette filter and the ash were also analyzed to determine the adsorption of toxic elements on the filter and their transference in smoke. The toxic effects of some of the elements have been briefly discussed.

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Abstract  

Potassium iron(III)hexacyanoferrate(II) supported on poly metylmethacrylate has been synthesized and investigated for the strontium(II) removal from HNO3 and HCl solutions. The ion exchange material characterized by different techniques and found to be stable in 1.0–4.0 M HNO3 solutions, has been used to elaborate different parameters related to ion exchange and sorption processes involved. The data collected suggested its use to undertake removal of Sr(II) from more acidic active waste solutions. Thus the material synthesized had been adjudged to present better chances of application for Sr(II) removal as compared to other such materials.

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Abstract  

A sensitive radiochemical procedure has been developed for the separation and determination of Dy, Sm, Gd, Eu, La and Lu in high purity uranium. The method is based on quantitative extraction of uranium using NPy/benzene as an extractant from 7M HCl solution. Rare earth elements (REE) remaining in the aqueous phase were subsequently determined by INAA.

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The elements Cd, Cr, Cu, Mn, Ni, Pb and Zn were determined in dust samples collected from air conditioner (AC) filters from 15 commercial sites of Lahore using flame atomic absorption spectroscopy (FAAS). The elements Cr, Mn and Zn were also determined using instrumental neutron activation analysis (INAA). The results obtained showed that higher amounts of these metals were measured in these dust samples than normally found in soil. This was especially true for Cd, Cu, Pb and Zn. Generally the amounts of Cd, Cr and Mn did not vary throughout the city of Lahore but the amounts of the traffic related Cu, Pb and Zn elements had the more variable ranges of 30–140, 30–230 and 74–2810 mg/kg respectively. The concentrations obtained for Cr, Mn and Zn by INAA were found to be higher than those obtained using FAAS. Analysis of the data obtained showed the digestion procedure employed to be the possible cause for this occurrence. It was also found that Mn was being over-estimated by INAA due to the interference from the Mg peak.

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Abstract  

Potassium iron(III) hexacyanoferrate(II) supported on poly methyl methacrylate, has been developed and investigated for the removal of lithium, rubidium and cesium ions. The material is capable of sorbing maximum quantities of these ions from 5.0, 2.5 and 4.5 M HNO3 solutions respectively. Sorption studies, conducted individually for each metal ion, under optimized conditions, demonstrated that it was predominantly physisorption in the case of lithium ion while shifting to chemisorption with increasing ionic size. Distribution coefficient (K d) values followed the order Cs+ > Rb+ > Li+ at low concentrations of metal ions. Following these findings Cs+ can preferably be removed from 1.5 to 5 M HNO3 nuclear waste solutions.

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Abstract  

INAA and AAS techniques have been employed to determine 40 elements in soil of a municipal waste dump in sector H-11, Islamabad. Background soil was also analyzed to study the extent of contamination of the dump site soil. Most of the major elements in these soils represented the geochemical composition of the soil in this area. The enrichment factors for quantified elements identified high Sb and Mg contents that could be attributed to the presence of PET and food materials in the waste. Geo-accumulation Index (I geo), Pollution Index (PI) and the Integrated Pollution Index (IPI) have also been calculated for all elements. The values for these indices show that municipal waste has distorted the soil ambiance and the soil of waste dump site is slightly to moderately polluted as compared to the background soil. The dump soil was found to be moderately polluted by the elements Ba, Br, Ga, Rb, Zn, Ni and Pb. Significantly high Cu, Mg and Sb contamination was observed for the waste soil that is likely to pose an environmental issue if current waste disposal procedures are continuously employed.

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Abstract  

The concentration of 32 elements was determined in phosphate rock samples from the Hazara phosphate deposits of Pakistan using instrumental neutron activation analysis (INAA) technique employing different irradiation protocols. These included 23 major, minor and trace elements (Al, As, Ba, Br, Co, Cr, Cs, Fe, Ga, Hf, K, Mn, Na, Rb, Sb, Sc, Sn, Ta, Th, U, V, Zn and Zr) and 9 rare earth elements (REEs) namely Ce, Eu, Ho, La, Lu, Nd, Sm, Tb and Yb. The results have been compared with the global values of these elements. The concentrations for most of the elements studied are lower than the concentrations reported in the literature whereas the concentrations of As, Co, Fe, K, Mn, Na and Sb are comparable. Two samples namely HR-4 and HR-5 have the highest concentrations for majority of the REFs with high enrichment factors. The quality assurance of data was performed through the concurrent use of Lake Sediment (SL-1) and GSJ-JR-1 (Rhyolite) reference materials. The acquired data will serve as a reference for the follow-up studies to assess the agronomic effectiveness of the Hazara phosphate rocks.

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Abstract  

Specific activity of natural radionuclides; 226Ra, 232Th and 40K were measured in the agricultural soil of eastern salt range of Pakistan using gamma ray spectrometry. The soil samples were collected within the ploughing region (up to 12 cm depth) and processed before analysis. The average specific activities of different radionuclides in the dry mass of soil samples were: 40K, (666 Bq/kg), 226Ra (51 Bq/kg), and 232Th (59 Bq/kg). The average outdoor terrestrial absorbed dose rate in air from gamma radiation one meter above ground surface was found to be 93 nGy/h.

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