Shameem Hasan

Adsorption characteristics of Cu and Ni on Irish peat moss

Peat has been widely used as a low cost adsorbent to remove a variety of materials including organic compounds and heavy metals from water. Various functional groups in lignin allow such compounds to bind on active sites of peat. The adsorption of Cu(2+) and Ni(2+) from aqueous solutions on Irish peat moss was studied both as a pure ion and from their binary mixtures under both equilibrium and dynamic conditions in the concentration range of 5-100mg/L. The pH of the solutions containing either Cu(2+) or Ni(2+) was varied over a range of 2-8. The adsorption of Cu(2+) and Ni(+2) on peat was found to be pH dependent. The adsorption data could be fitted to a two-site Langmuir adsorption isotherm and the maximum adsorption capacity of peat was determined to be 17.6 mg/g for Cu(2+) and 14.5mg/g for Ni(2+) at 298 K when the initial concentration for both Cu(2+) and Ni(2+) was 100mg/L, and the pH of the solution was 4.0 and 4.5, respectively. Column studies were conducted to generate breakthrough data for both pure component and binary mixtures of copper and nickel. Desorption experiments showed that 2mM EDTA solution could be used to remove all of the adsorbed copper and nickel from the bed.

Adsorption of Chromium(VI) on Chitosan‐Coated Perlite

Chitosan‐coated perlite beads were prepared by drop‐wise addition of a liquid slurry containing chitosan and perlite to an alkaline bath. The beads were characterized by SEM and EDS x‐ray microanalysis. The chitosan content of the beads was 23%, as determined by a pyrolysis method. Adsorption of hexavalent chromium from aqueous solutions on chitosan‐coated perlite beads was studied under both equilibrium and dynamic conditions. The effect of pH on adsorption was also investigated. The data were fitted to the Langmuir adsorption isotherm. The adsorption capacity of chitosan‐coated perlite was found to be 104 mg/g of adsorbent from a solution containing 5000 ppm of Cr(VI). On the basis of chitosan, the capacity was 452 mg/g of chitosan. The capacity was considerably higher than that of chitosan in its natural and modified forms, which was in the range of 11.3 to 78 mg/g of chitosan. The beads loaded with chromium were regenerated with sodium hydroxide solution of different concentrations. A limited number of adsorption‐desorption cycles indicated that the chitosan‐coated beads could be regenerated and reused to remove Cr(VI) from waste streams.

Microfiltration of water-based paint effluents

Abstract The major hurdle associated with water recycling in water-based paint manufacturing processes is microbial contamination and related deterioration of product quality and shelf life. The common problems associated with microbial degradation are change in viscosity, pH, colour and loss of surface adhesion properties. Owing to these reasons, water recycling is not widely practised in water-based paint manufacturing processes. The present study focuses on tertiary treatment of effluent by chemical coagulation and cross-flow microfiltration (0.2 μm pore size) to produce water of sufficient quality for reuse in various stages of water-based paint manufacturing. The coagulation and flocculation were carried out in a ‘jar test’ rig at a controlled pH, and coagulant dosage was optimised by turbidity and zeta potential measurements. The filtrate was subjected to cross-flow microfiltration and permeate was tested for necessary quality attributes. Screening of aerobic microbes and fungi were conducted by streaking the samples on nutrient agar and malt extract agar, respectively. Iron sulfide agar tubes were used for screening anaerobic microbes or the sulfate reducing bacteria. The tests showed that permeate was free from microorganisms. The process was implemented in a paint manufacturing plant in Malaysia, which resulted in 55% reduction in water consumption.

Adsorption of uranium on a novel bioadsorbent-chitosan-coated perlite

Chitosan was coated on an inert substrate, perlite, and was prepared as spherical beads for adsorption of uranium from aqueous solutions. The uptake capacity of chitosan-coated perlite beads for uranium varied from 98.9 to 149 000 μg/g when the equilibrium concentration of uranium in the solution ranged from 11 ppb (11 μg/l) to 1000 ppm (10 × 106 μg/l) and the solution pH was 5. The adsorption capacity of chitosan-coated perlite beads for uranium decreased by 75% in the presence of 0.45 M NaCl, whereas the adsorption capacity decreased by 55% when TiO2 was added to the beads during their preparation. The adsorption capacity of TiO2-containing chitosan beads for uranium was found to be in the range of 2.5 to 40 μg of uranium per gram of beads when the concentration of uranium was 39 to 734 μg/l in the presence of 0.45 M NaCl. It was in the range of 18 to 302 μg of uranium per gram of beads when the concentration was 990 to 47 000 μg/l in the presence of 0.45 M Na2CO3. Chitosan-coated beads were found to preferentially adsorb uranium, Cd, and Cr from a mixture containing these ions along with Sr and Cs. Only a negligible amount of Sr and Cs was adsorbed by chitosan-coated beads. The data suggest that the chitosan-coated beads can be used for both extraction of uranium from waste streams and also from a highly acidic medium such as a reprocessing stream that uses nitric acid.

Preparation and evaluation of Fuller's Earth Beads for removal of Cesium from waste streams

Abstract Fullers earth beads and cylinders were prepared using chitosan and sodium silicate as binders, respectively, for removal of cesium ion from aqueous solutions. The cost of the adsorbent is expected to be significantly lower as the raw materials are low cost materials and readily available. The adsorbents were characterized by SEM, EDS, and x‐ray microanalysis. Adsorption capacity of the beads was evaluated under both batch and dynamic conditions. The adsorption capacity for Fullers earth beads was found to be 26.3 mg/g of adsorbent at 293 K when the liquid phase concentration of cesium was 1000 mg/L. The adsorption capacity of Fullers earth cylinder was found to be higher than that of beads, however, it was concluded that the alkaline nature of the cylinder precipitated out cesium increasing its capacity. The capacity of Fullers earth beads decreased by almost 62% when 1 mol/L NaCl and 2.25 mmol/L of strontium were present in the solution. The Freundlich, the Langmuir isotherm equations, and a modified Polanyis equation were used to correlate the data. The isosteric heats of adsorption suggested the heterogeneity of the surface and multilayer coverage. The first order reversible kinetic model adequately described the dynamic system during the adsorption process. The adsorption (k1) and desorption (k2) rate constants were evaluated from the dynamic model.

On-Chip Initiation and Burn Rate Measurements of Thermite Energetic Reactions

Burn rates of various nano-energetic composites were measured by two techniques; on-chip method and conventional optical method. A comparison is presented to confirm the validity of on-chip method. On-chip initiators were prepared using platinum heater films and nanoenergetic composites. Thin film Pt heaters were fabricated with different dimensions and ignition delay was studied using a nano-energetic composite of CuO nano-rods and Al-nano-particles. The ignition delay as a function of electrical power is presented for the same energetic composite. Heater with smaller surface area is found to be more efficient, which may be due to the lower heat losses.

Dispersion of FeOOH on Chitosan Matrix for Simultaneous Removal of As(III) and As(V) from Drinking Water

Bio-inorganic chitosan based spherical shaped beads were prepared by dispersing rod-shaped FeOOH nanoparticles into a chitosan matrix for the removal of pure As(III) and As(V) from aqueous media, such as drinking water. A homogeneous mixture of chitosan and ferric nitrate, ferric chloride was prepared respectively with or without oxalic acid. The mixture was added dropwise in to a NaOH bath, where iron salts reacted with NaOH to form FeOOH particles. The scanning electron microscopy (SEM) showed that rod shaped FeOOH particles were distributed homogenously in the chitosan matrix. Diffuse reflective UV-vis (DRUV) spectra revealed that hydrated iron oxide formed a complex with functional groups in chitosan. Adsorption of As(III) and As(V) on different iron salt based bead was found to be pH dependent. The bead prepared from iron nitrate showed better performance for arsenic removal from aqueous solution over the bead that was prepared using iron chloride salt. The bead prepared using chitosan and iron-FeOOH is known as a chitosan-iron oxyhydroxide (CFOH) bead. The CFOH beads were found to be more efficient in removing As(III) from the solution compared to As(V). The adsorption of As(III) and As(V) from aqueous solution on CFOH beads was studied under equilibrium conditions in the concentration range of 1 mg/L to 50 mg/L in the presence of 0.05 M NaNO3 at pH 6.5 and 298 K temperature. The maximum adsorption capacity of the CFOH bead was found to be 5.4 mg/g for As(V) and 7.2 mg/g for As(III) using the Langmuir equation. The presence of sulphate, phosphate, and silicate in aqueous solution had no effects on adsorption of either As(III) or As(V) on CFOH beads but decreased significantly at pH> 8.

SYNTHESIS OF URANIUM OXIDE NANOPARTICLES IN AQUEOUS SOLUTIONS

Abstract Uranium oxide nanoparticles can be used as a catalyst for a number of chemical reactions, including gas-phase destruction of organic chemicals. These particles can also be used in high-temperature catalytic applications such as the decomposition of water. In this paper we present a method for preparation of uranium oxide nanoparticles at room temperature using a surfactant templating-crystal growth technique. The size and shape of the particles were controlled by selecting appropriate surfactant micelles. Hexagonal-shaped particles were obtained when PEG-400 was used as the surfactant, whereas particles were rodlike shaped when Pluronic-123 was employed. Particles were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), and ultraviolet-spectrometric analysis. They were found to be 500 to 1000 nm in length for hexagonal particles and 100 to 500 nm in length and 20 to 40 nm in width for rodlike particles. The FTIR spectra taken in diffuse reflectance infrared Fourier transform mode showed an infrared band at 910 cm-1 corresponding to asymmetric U=O stretching vibration of uranyl species. When the sample was heated at 600°C, four bands—at 353, 412 to 475, 745, and 805 cm-1—were observed in the Raman spectrum. The bands in the range of 412 to 475 cm-1 and at 745 cm-1 could be attributed to U3O8 and UO2+2 (uranyl) species that are present in the sample.

Synthesis of Silica-Coated Uranium Oxide Nanoparticles by Surfactant-Templated Sol-Gel Process for Use as Catalysts

Uranium oxide (U3O8) nanoparticles were synthesized and coated in situ with porous, mesostructured silica using a modified sol-gel method for use as a catalyst. The catalytic property of coated U3O8 nanoparticles was evaluated by exposing them to an aqueous solution of benzene at 500 mg/l at room temperature. The presence of benzene was not detected by an ultraviolet (UV)-visible (UV-vis) spectrometer after 6 weeks of exposure to coated uranium oxide nanoparticles, indicating the particles’ potential as a catalyst. Based on the results of the benzene destruction, it may be suggested that the coated U3O8 nanoparticle-based catalyst has the potential to destroy hydrocarbons, aromatics, and various toxic substances such as perchlorates and 1,4-dioxane from groundwater. However, further experiments are necessary to explore the full potential of the catalyst. Pluronic-123, n-butanol, and 2-propanol were used as surfactant, cosurfactant, and continuous phase, respectively, for the synthesis of the U3O8 nanoparticles, which were formed through nucleation, growth, and subsequent aggregation in the solution phase. The nanoparticles were coated in situ using an aqueous solution of tetraethyl orthosilicate. The coated particles were characterized using transmission electron microscopy, diffuse reflectance infrared Fourier transform spectroscopy, nitrogen physisorption, X-ray diffraction, and diffuse reflectance UV-vis spectroscopy. These measurements revealed that U3O8 particles ranging from 4- to 10-nm were distributed exclusively inside the silica matrix.