Nagwa A. Badawy

Effect of ionic strength on the adsorption of copper and chromium ions by vermiculite pure clay mineral.

It is important to assess the effects of ionic strength when studying adsorption of metal ions on clay mineral because the background salt may complex metals and compete for adsorption sites. The sorption behavior of vermiculite pure clay mineral has been studied with respect to copper and chromium as a function of ionic strength in single metal ion solutions. Background electrolytes used in these experiments were KCl, NaCl and NH4Cl. The studies were conducted by a batch method at temperature 25 degrees C. The adsorption capacity and adsorption energy for each metal ion were calculated from the Langmuir adsorption isotherm. Also the competitive adsorption behavior of some heavy metal ions such as Cr(III), Cu(II), Ni(II) and Co(II) by vermiculite pure clay mineral was studied. The result shows the competition between coexisting heavy metal cations for the same adsorption sites of an adsorbent. However, when trivalent metal was added to the solution it competitively replaced divalent ions that had been previously adsorbed onto the vermiculite pure clay mineral, resulting in the desorption of these metals into the solution.

Purification of wet process phosphoric acid by decreasing iron and uranium using white silica sand.

Natural white silica sand as an adsorbent has been developed to reduce the concentration of iron and uranium ions as inorganic impurities in crude Egyptian phosphoric acid. Several parameters such as adsorbate concentration, adsorbent dose, volume to weight ratio and temperature, were investigated. Equilibrium isotherm studies were used to evaluate the maximum sorption capacity of adsorbent. Thermodynamic parameters showed the exothermic nature of the process and the negative entropy reflects the affinity of the adsorbent material towards each metal ion.

Chromatographic separations and recovery of lead ions from a synthetic binary mixtures of some heavy metal using cation exchange resin.

A simple solid phase extraction procedure on cation exchange resin Purolite C100 is presented. The procedure based on a column technique for separation and recovery of lead ions from synthetic binary mixtures. Equilibrium distribution coefficient, k(d) for the different metal ions such as Al(III), Fe(III), Ba(II) and Pb(II) in the presence of nitric acid and ammonium acetate solutions of variable concentrations was determined at 25 degrees C. The values of separation factor, alpha were evaluated. Quantitative separation of lead ions from a synthetic binary mixtures are based on the fact that ammonium acetate is a good elute for lead ions but fails to elute the other cations.

Titania modified activated carbon prepared from sugarcane bagasse: adsorption and photocatalytic degradation of methylene blue under visible light irradiation

ABSTRACT Activated carbon (AC), prepared from sugarcane bagasse waste through a low-temperature chemical carbonization treatment, was used as a support for nano-TiO2. TiO2 supported on AC (xTiO2–AC) catalysts (x = 10, 20, 50, and 70 wt.%) were prepared through a mechano-mixing method. The photocatalysts were characterized by Raman, X-ray diffraction analysis, FTIR, SBET, field emission scanning electron microscope, and optical technique. The adsorption and photo-activity of the prepared catalysts (xTiO2–AC) were evaluated using methylene blue (MB) dye. The photocatalytic degradation of MB was evaluated under UVC irradiation and visible light. The degradation percentage of the 100 ppm MB at neutral pH using 20TiO2–AC reaches 96 and 91 after 180 min under visible light and UV irradiation, respectively. In other words, these catalysts are more active under visible light than under UV light irradiation, opening the possibility of using solar light for this application.

Visible light sensitive activated carbon-metal oxide (TiO2, WO3, NiO, and SnO) nano-catalysts for photo-degradation of methylene blue: a comparative study

Abstract Four composites of metal oxide doped with activated carbon with a metal oxide weight of 20% were prepared using mechano-mixing method. The nano-catalysts were characterized by N2-adsorption–desorption, X-ray diffraction analysis, transmission electron microscopy, Fourier-transform infrared spectroscopy, UV-diffuse reflectance, and photoluminescence spectroscopy. Photo-catalytic degradation of methylene blue dye under UV 254  nm and visible light was examined. In general, prepared catalysts are more active for degradation of dye under visible light than UV, reaching 96% within 180 min irradiation using the SnO catalyst. Photo-degradation of methylene blue followed pseudo first order reaction mechanism with a rate constant of 14.8 × 10−3 min−1, and the time required for removal of 50% of dye was 47 min.

In vitro evaluation of mucoadhesive and self-disinfection efficiency of (acrylic acid/polyethylene glycol)-silver nanocomposites for buccal drug delivery

A mucoadhesive drug delivery system can improve the effectiveness of a drug, allowing targeting and localization at a specific site. According to this assumption, γ-irradiation as eco-friendly technique was employed to synthesize (acrylic acid/polyethylene glycol) copolymer hydrogel of different compositions. Silver nanoparticles were prepared within (acrylic acid/polyethylene glycol) hydrogel network by means of in situ reduction of silver nitrate using sodium borohydride as a reducing agent. Swelling characteristics in distilled water and simulated saliva solution were studied as a function of copolymer composition and preparation irradiation dose. (Acrylic acid/polyethylene glycol) hydrogels and their developed Agº nanocomposites have been characterized using scanning electron microscope, thermogravimetric analysis, transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Mucoadhesive strength as well as self-disinfection efficiency expressed as antibacterial activity against different bacterial strains was evaluated. Propranolol HCl as model drug was used to evaluate the potential efficiency of the obtained (acrylic acid/polyethylene glycol)-Agº nanocomposites as mucoadhesive drug carrier. The obtained results showed that the (acrylic acid/polyethylene glycol)-Agº nanocomposites show a promising self-disinfection property, and the propranolol HCl–loaded composites were able to deliver the loaded drug in a sustainable manner that lasts for about 600 min.

Radiation fabrication of Xanthan-based wound dressing hydrogels embedded ZnO nanoparticles: In vitro evaluation

Depending on the biocompatibility of Xanthan, polyvinyl alcohol and the antibacterial efficiency of zinc oxide nanoparticles (ZnO), a series of (Xanthan-polyvinyl alcohol)/ZnO nanocomposite hydrogels were prepared as wound dressing using eco-friendliness 60Co γ-ray irradiation facility. ZnO nanoparticles were characterized using X-ray diffraction, UV-vis spectroscopy, transmission electron microscopy and energy dispersive X-ray analysis. The size of ZnO nanoparticles was ranged between 15 and 25 nm. The presence of ZnO nanoparticles reconstructed the internal structure of the hydrogel network which aid in a homogenous porous structure as indicated by scanning electron micrographs. Such adequate porosity along with the presence of ZnO nanoparticles controls the fluid uptake ability, water retention and water vapor transmission rate. The fluid uptake ability in pseudo-extracellular fluid and water ranged between (554-664%) and (1281-1603%), respectively. After exposure to air for 6 h, ZnO dressings kept about 50-65% of their water content which makes them more suitable for moderate exudating wounds. Water vapor transmission rate ranged between 167 and 184 (g/(m2 h) which is sufficient to keep wounds surface moist. ZnO dressings show an efficient microbial barrier potency and profound antimicrobial activity against Staphylococcus aureus, Escherichia coli and Candida albicans. In vitro cytotoxicity and haemolytic potency evaluation showed their biocompatibility.