Medhat Mohamed El-Moselhy

Carminic acid modified anion exchanger for the removal and preconcentration of Mo(VI) from wastewater

Removal and preconcentration of Mo(VI) from water and wastewater solutions was investigated using carminic acid modified anion exchanger (IRA743). Various factors influencing the adsorption of Mo(VI), e.g. pH, initial concentration, and coexisting oxyanions were studied. Adsorption reached equilibrium within <10 min and was independent of initial concentration of Mo(VI). Studies were performed at different pH values to find the pH at which maximum adsorption occurred and was determined to be at a pH between 4.0 and 6.0. The Langmuir adsorption capacity (q(max)) was found to be 13.5mg Mo(VI)/g of the adsorbent. The results showed that modification of IRA743 with carminic acid is suitable for the removal of Mo(VI), as molybdate, from water and wastewater samples. The concentration of Mo(VI) was determined spectrophotometrically using bromopyrogallol red as a complexation reagent. This allows the determination of Mo(VI) in the range 1.0-100.0 μg/mL. The obtained material was subjected to efficient regeneration.

Silica coating and photocatalytic activities of ZnO nanoparticles: effect of operational parameters and kinetic study.

Silica-coating ZnO nanoparticles were prepared using the hydrothermal method. The prepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray Spectroscopy (EDX). It was found that ultrafine core/shell structured silica-coating ZnO nanoparticles were successfully obtained. TEM analysis revealed a continuous and uniform silica coating layer of about 8nm in thickness on the surface of ZnO nanoparticles. The photocatalytic performance of silica-coating ZnO core/shell nanoparticles in methylene blue aqueous solution was investigated. The effects of some operational parameters such as pH value, nanocatalyst loading and initial MB concentration on the degradation efficiency were discussed. Kinetic parameters were experimentally determined and a pseudo-first-order kinetic was observed. Thus, the main advantage of the coating is the stability of the photocatalysts and the better performance in acidic or alkaline solutions. Compared to ZnO the maximum apparent rate constant is obtained at pH 8.5 (pH 11.5 in case of bare ZnO). Moreover, the Langmuir adsorption model was applied to describe the equilibrium isotherm at different MB concentration. The applicability of the Langmuir isotherm suggests monolayer coverage of the MB onto surface of silica-coating ZnO nanoparticles. The kinetics of the adsorption with respect to the initial dye concentration, were also investigated. The pseudo-first-order and second-order kinetic models were used and the rate constants were evaluated. The kinetic studies revealed that the pseudo-second-order kinetic model better represented the adsorption kinetics, suggesting that the adsorption process may be chemisorption.

Structural modification of mordenite zeolite with fe for the photo-degradation of edta

Fe(2+) was incorporated inside mordenite through ion exchange technique in aqueous solution. The amount of Fe loading was 25-100 wt %, using FeSO(4).7H(2)O as precursor and Na-mordenite starting material Na-M. The Fe incorporated (Fe-M) thus prepared was characterized by XRD, FTIR and N(2) adsorption measurements. It was found that Fe mordenite retained the same structure as that for Na-mordenite which may indicate that Fe well dispersed into mordenite channels. BET indicated that Fe-M samples possessed higher surface area compared to the parent Na-M. Photocatalytic degradation of EDTA was carried out in presence of the prepared Fe-M catalysts. Effects of catalyst concentration and temperature were also studied. Thermodynamic parameters calculated for 50% Fe-M showed the highest catalytic activity toward EDTA degradation.

Photo-degradation of acid red 44 using Al and Fe modified silicates.

Al and Fe modified silicates were synthesized using the hydrothermal method. The obtained materials were calcined at different temperatures (250, 500 and 750 degrees C) and characterized using XRD, FTIR, UV and SEM spectroscopy. The obtained materials were applied for the photo-decolorization of acid red 44 as a member of azo dye family, in aqueous medium using UV irradiation (lambda=254 nm) under different experimental conditions. The effect of calcination temperature, catalyst concentration and pH on the decolorization of acid red 44 dye were investigated. The decolorization of acid red 44 dye and the decreasing in concentration of the formed intermediates have been followed using UV-vis spectrophotometry and high performance liquid chromatography (HPLC). Results showed that the addition of Al and Fe-silicate to the dye solution as well as pH change greatly enhanced the rate of degradation. The decolorization followed the pseudo first order kinetics model and a significant mineralization of AR44 was observed.

Synthesis and characterization of hybrid iron oxide silicates for selective removal of arsenic oxyanions from contaminated water

A series of hybrid silicates containing iron oxides was synthesized by adding various amounts of iron into silica on the basis of using post precipitation mechanism from aqueous solutions in order to form hydrated iron oxide species (HFO). The obtained materials were characterized by XRD, SEM, TEM, FTIR, Zeta potential and low temperature nitrogen sorption. XRD analysis confirmed that HFO-Si was amorphous and iron oxide crystals in the silica cannot be detected due to the lower size of HFO, which is the probability of its occupied interstitial positions in the silicate matrix. However, TEM image showed the presence of nano-sized HFO located inside the silicate matrix. The adsorption properties and selective efficiency of the synthesized materials were examined with respect to the removal of As(V) and As(III) species from contaminated water under different experimental conditions and in the presence of competing anions. Increasing iron loading enhanced the arsenic adsorption capacity of HFO-Si; the maximum level of arsenic removal was 300mg As/g HFO-Si after 5 successive loads.

Copper modified exchanger for the photodegradation of methyl orange dye

AbstractA Cu modified hybrid exchanger was synthesized by loading Cu(II) onto the sulfonic acid sites of the C-145 cation exchanger by passing CuSO4 solution followed by treatment with sodium hydroxide to deposit the copper hydroxide particles. Each hybrid sorbent particle is essentially a spherical macroporous cation exchanger bead within which agglomerates of nanoscale hydrated Cu oxide particles have been uniformly and irreversibly dispersed using a simple chemical–thermal treatment. The obtained material was characterized using X-ray diffraction, energy-dispersive X-ray spectroscopy and scanning electron microscope. The obtained materials were applied for the photo-decolorization of methyl orange as a member of the azo dye family, in an aqueous medium using UV irradiation (λ = 254 nm) under different experimental conditions. The effect of catalyst concentration and pH on the decolorization of methyl orange dye was investigated. The decolorization of methyl orange dye has been followed using UV–vis spe...

Binary Fe and Mn Oxide Nanoparticle Supported Polymeric Anion Exchanger for Arsenic Adsorption: Role of Oxides, Supported Materials,and Preparation Solvent

In this work, binary Fe/Mn oxide nanoparticles were incorporated onto the matrix of anion exchange resin, resulting in hybrid polymeric/inorganic nanoadsorbent named as A502P-Fe/Mn. During synthesis process, effects of various types of metal oxides, preparation solvent, supporting materials, and loading cycles were also investigated. To reduce the charge repulsion force between cationic Fe3+ and Mn4+ ions and fixed-positively charged quaternary amine (R4N+) functional groups of the anion exchange support, mixed solution containing DI/ethanol was introduced to dissolve metal salts during the preparation process. The data obtained by equilibrium batch test indicated that the A502P-Fe/Mn prepared from mixed 50:50 of DI and ethanol exhibited the highest As (V) sorption capacity. The synthesized material was further characterized by using scanning electron microscope (SEM) equipped with energy dispersive X ray spectroscopy (EDX) to verify the existence and distribution of elemental Fe, Mn, and As inside the polymeric beads. Equilibrium As (V) sorption isotherm, effect of solution pH, and point of zero charge of material were also evaluated. This A502P-Fe/Mn can have a promising potential for arsenic removal applications.

Trace Lead Removal in Drinking Water Using High Capacity Polymeric Supported Hydrated Iron Oxide Nanoparticles

Ferric oxide nanoparticles are environmentally benign and can be selective toward lead, especially in neutral to mildly alkaline pH of groundwater. However, due to very fine particles and low mechanical strength, it prevents these materials to apply in point of use filter or large scale fixed-bed adsorption. In this study, polymeric gel cation exchanger, Purolite C100, supported ferric oxide nanoparticles, C100-Fe, was synthesized, characterized, and tested with challenging water according to NSF standards 53. From SEM-EDX studies, it can imply that high concentration of iron can be doped and distributed within the gel phase structure of the C100 approximately 22% by mass. The TEM micrographs confirm the size of hydrated ferric oxide fall into the nanometer range about 10-60 mm. The fixed-bed adsorption experiments demonstrated that C100-Fe can remove lead below the stringent standard of 0.05 mg/L up to 15,000 BVs, whereas the GAC, GAC-Fe, and C100 can treat the same test water only 1200, 1700, and 3500 BVs, respectively. The results confirm that C100-Fe can be efficiently substituted to the traditional GAC for lead removal in drinking water.