Search Results

You are looking at 1 - 10 of 32 items for

  • Author or Editor: M. Rahman x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

A simple and sensitive method for the determination of some metalloids and heavy metals in water samples is presented. The method is based on the preconcentration of the attachment of chelating functionalities with metalloids and toxic metals irreversibly and targeted towards toxic metals adsorbed on modified activated carbon, activated carbon and red soil particles at pH 3.0–9.0±0.2, followed by quantitative determination using instrumental neutron activation analysis (INAA), on the absorbers. Attachment results from attraction that may be physical, chemical, electrical, or a combination of all three. The efficient removal of metalloids and toxic metals, especially arsenic, chromium and mercury is anticipated. The adsorption capacity of the chemically modified activated carbon materials was evaluated for the above mentioned metalloid and toxic metal ions in the presence of iron ions and simulated water samples. Red soil particles containing iron was utilized in the control of oxidation-reduction reaction with metalloids and toxic metals. The preconcentration of the elements of interest on red soil particles, activated carbon and modified activated carbon at different depths, pH and oxidation states was investigated. The results obtained showed good agreement with certified values giving relative errors of less than 10%.

Restricted access

Abstract  

Results are reported on lab-scale experiments on the removal of134Cs and60Co from liquid radioactive waste originating from Radioisotope Production Laboratory. Low cost and-simple nickel ferro-cyanide precipitation was applied for the separation of radionuclides from low-level radioactive liquid waste. Using the optimal nickel concentration of 0.75M and optimum cyanide concentration of 0.50M about 98% of the134Cs can be removed at an optimum pH of nearly 10. Furthermore, using the same method nearly 60% of60Co has been removed. The nickel ferrocyanide precipitation method could be used for removal of Cs from low level liquid waste.

Restricted access

Abstract  

A new filtering column has been developed on the covalent attachment of chelating functionalities to simple, highly hydrophilic adsorbent material, which can then complex heavy metal ions irreversibly and targeted towards toxic metals removal. The capacity of the chemically modified sorbent (modified charcoal) materials used in this work was evaluated for the above mentioned heavy metal ions in the presence of iron ions and simulated water samples. The methods are based on preconcentrations of the elements of interest on activated carbon and zirconium loaded activated carbon using specific conditions of pH and oxidation states followed by a final determination by neutron activation analysis (NAA). It has been investigated that zirconium loaded activated carbon is able to adsorb As (V), Se (VI), Cr (VI) and Hg (II) at any pH while activated carbon is able to adsorb As (III), Se (IV), Cr (III) and Hg(I) at higher pH.

Restricted access

The study presents an analysis of spatial and structural diversity of Sal ( Shorea robusta ), the dominant species of sal forests in Bangladesh by using a neighbourhood analysis approach. The simple field method permits relatively unskilled persons to collect data. Most of the indices can be calculated in the field and the data analysis is comparatively easy. Therefore, the applicability of the method was tested by using different setting of reference trees compared with the full sampling for each plot in the Madhupur sal forests. The results indicate that a group of one reference tree and its four neighbours can be used efficiently to describe the spatial and structural diversity in homogeneous young forests at low costs and in short time. The indices can be easily interpreted allowing quantitative comparisons between different types of forest stands. Sal can be considered as the dominant and comparatively faster growing species than other associate species.

Restricted access

Abstract  

Determination of toxic elements Cd, Pb and other heavy metals has been carried out for Rawalpindi - Islamabad region using the moss monitoring technique. The carpet moss samples (Hypnum Cupressiforme) were collected over an area of 196 km2 around lignite/coal-fired brick kilns for regular periods of time during 1997–1999. The elements were extracted into solution with multiacid digestion and then analyzed by atomic absorption spectrometry. The metal contents in moss samples from sites adjacent to coal-fired brick kilns was higher as compared to samples collected from the sites away from that sources. The results obtained by the "BIOMONITORING" technique, for the first time in this area, are presented.

Restricted access

This study examines types of compounds other than the Synthetic Genitive Construction (SGC) in Modern Standard Arabic (MSA) and Jordanian Arabic (JA), discussing the word class of the parts of the compound and identifying the head. The analysis reveals that there are four types of compounds in MSA, and three in JA. The Prep + Prep combination is missing from JA. I also argue that the word class of the parts of the compound of Arabic in general, and of MSA in particular, is not diverse. Regarding the head, I suggest that N + N compounds other than the SGC, Adj + Adj compounds and reduplicated compounds can be either semantically double-headed or headless

Full access

Abstract  

Membranes, based on tri-n-octylamine (TOA) xylene liquid, supported in hydrophobic microporous films have been used to study the transport of Pd(II) ions, after extraction into the membrane. Various parameters, such as the effect of hydrochloric acid concentration in the feed solution, TOA concentration in the membrane phase, effect of stripping agent like nitric acid concentration, and temperature on the flux of Pd(II) ions across the liquid membranes have been investigated. The optimum conditions of transport for these metal ions determined are, TOA concentration, 1.25 mol·dm–3, HCl concentration in the feed solution, 5 mol·dm–3, and concentration of nitric acid used as a stripping, agent 5 mol·dm–3. The maximum values of the flux and permeability determined under the optimum condition are 23·10–6 mol·m–2·s–1 and 2.40·103 m2·s–1 at 25°C. The results obtained have been used to elucidate the mechanism of palladium transport.

Restricted access

Abstract  

Целяу даннои работы является введение пространства последователяностеиces[(p n ), (q n )] и характериэация классов матриц (ces[(p n ), (q n )],ℓ) и (ces[(p n ), (q n )],c), где ℓ и с — пространства ограниченных и, соответственно, сходяшихся комплексных последователяностеи. При специаляном выборе последователяностеи {p n } и {q n } получаутся некоторые иэвестные следствия.

Restricted access

Abstract  

The influence of methyl metharcylate and gamma exposure dose on the physico-chemical and mechanical properties of polymer-alite composite have been investigated. The hardened alite samples were impregnated with a methyl methacrylate monomer and then subjected to γ irradiation doses from 10–50 KGy. The effect of polymer loading (%), compressive strength, bulk density and the microstructure (scanning electron microscopy SEM), in addition IR spectra were studied. The results indicate that, polymer loading, compressive strength and bulk density increase with increasing absorbed dose. This is attributed to the deposition of the polymer in the pores of the samples. SEM showed the voids between the particles in the samples before the impregnation, whereas, the formation of new products in the pores appeared after impregnation.

Restricted access