Showing papers by "Tawfik A. Saleh published in 2015"

Isotherm, kinetic, and thermodynamic studies on Hg(II) adsorption from aqueous solution by silica- multiwall carbon nanotubes

Abstract: Silica combined with 2% multiwall carbon nanotubes (SiO2-CNT) was synthesized and characterized. Its sorption efficacy was investigated for the Hg(II) removal from an aqueous solution. The effect of pH on the percentage removal by the prepared material was examined in the range from 3 to 7. The adsorption kinetics were well fitted by using a pseudo-second-order model at various initial Hg(II) concentrations with R (2) of >0.99. The experimental data were plotted using the interparticle diffusion model, which indicated that the interparticle diffusion is not the only rate-limiting step. The data is well described by the Freundlich isotherm equation. The activation energy (Ea) for adsorption was 12.7 kJ mol(-1), indicating the process is to be physisorption. Consistent with an endothermic process, an increase in the temperature resulted in increasing mercury removal with a ∆H(o) of 13.3 kJ/mol and a ∆S(o) 67.5 J/mol K. The experimental results demonstrate that the combining of silica and nanotubes is a promising alternative material, which can be used to remove the mercury from wastewaters.

Mercury sorption by silica/carbon nanotubes and silica/activated carbon: a comparison study

Abstract: Nanocomposites of silica incorporated with carbon nanotubes (silica/CNT) and activated carbon (silica/AC) were synthesized and characterized by scanning electron microscopy (SEM), element mapping, energy dispersive X-ray spectroscopy (EDX), thermogravimetric analyzer (TGA) and Fourier transform infrared spectroscopy (FTIR). Silica/CNT and silica/AC were investigated for efficient removal of mercury ions from aqueous solutions. The adsorbents have been analyzed on the basis of adsorption capacity, reusability, and their application in packed columns. The effects of experimental parameters, like pH, contact time and initial concentrations on the adsorption of mercury ions, were optimized. The kinetic data for the adsorption process obeyed a pseudo-second-order kinetic model with R2 of 0.999. Fitting the data to an intraparticle diffusion model indicated that surface adsorption and intraparticle diffusion were concurrently operating. In addition, this study used the Langmuir, Freundlich and Temkin isotherms to describe the behaviour of equilibrium adsorption. The equilibrium adsorption of the studied mercury ions is best fitted using the Freundlich isotherm, with silica/CNT of higher capacity than silica/AC. The silica/CNT showed better performance than silica/AC indicating silica/CNT has better efficiency.

Applying Nanotechnology to the Desulfurization Process in Petroleum Engineering

Abstract: Description: As regulations push the fossil fuel industry toward increasing standards of eco-friendliness and environmental sustainability, desulfurization (the removal of SO2 from industrial waste byproducts) presents a new and unique challenge that current technology is not equipped to address. Advances in nanotechnology offer exciting new opportunities poised to revolutionize desulfurization processes. Applying Nanotechnology to the Desulfurization Process in Petroleum Engineering explores recent developments in the field, including the use of nanomaterials for biodesulfurization and hydrodesulfurization. Readers: The timely research presented in this volume targets an audience of engineers, researchers, educators as well as students at the undergraduate and postgraduate levels.

Synthesis of exfoliated polystyrene/anionic clay MgAl-layered double hydroxide: structural and thermal properties

Abstract: Exfoliated polystyrene/layered double hydroxide (PS/LDH) nanocomposites were prepared by direct intercalation of PS into MgAl LDH at 60 °C. The MgAl LDH as the nanofiller was modified via the precipitation of the salt mixture of magnesium and aluminum metals by sodium dodecyl sulfate (SDS). Various techniques, Fourier Transformed Infrared Spectroscopy (FTIR), X-Ray-diffraction (XRD), Filed Emission Transmission Electron Microscopy (FETE) and thermo gravimetric analyses (TGA) were employed for structural properties and thermal stability of the nanocomposites. FTIR spectra indicated the presence of both functional groups of SDS–LDH and PS. XRD patterns and TEM images indicated the formation of amorphous dispersed and exfoliated nanocomposites. Increase in thermal stability with SDS–MgAl LDH content was observed by TGA and DTG through the T0.5 (T0.5 the degradation temperature at 50%) and Tmax (Tmax the maximum rate of change) with a maximum obtained for a loading of 2 and 4 wt%.

Evaluation of AC/ZnO composite for sorption of dichloromethane, trichloromethane and carbon tetrachloride: kinetics and isotherms

Abstract: The present work reports on the efficiency of activated carbon loaded with zinc oxide nanoparticles (AC/ZnO) for removing dichloromethane, trichloromethane and carbon tetrachloride from aqueous solutions Waste tires were used as a raw material for the production of activated carbon (AC) by thermo-chemical process Zinc oxide nanoparticles were loaded into AC by using Zn(NO3)26H2O The AC/ZnO composite has been characterized by BET analyzer, scanning electron spectroscope, energy dispersive X-ray spectroscope, FTIR spectrophotometer, and X-ray diffraction Batch experiments were conducted under various adsorbent dosages, initial concentrations and contact time Rapid adsorption was observed with adsorption capacity of 667 mg/g for dichloromethane, 1191 mg/g for chloroform and 1610 mg/g for carbon tetrachloride The equilibrium was obtained in 20 min of contact time The adsorption of these pollutants onto AC/ZnO was described well by the pseudo second-order model, and the hydrophilic fraction adsorption fitted the intraparticle diffusion model Freundlich and Langmuir models were used to evaluate the process, and the Langmuir adsorption isotherm model fitted the data better than other models The reusability of the composite was proved when no significant decrease in its adsorption capacity was observed even after several times of regeneration

Synthesis of a unique cross-linked polyzwitterion/anion with an aspartic acid residue and its use for Pb2+ removal from aqueous solution

Abstract: In this work, a unique cross-linked polyzwitterion/anion with an aspartic acid residue was synthesized via butler's cyclopolymerization protocol involving N,N-diallylaspartic acid hydrochloride, 1,1,4,4-tetraallylpiperazinium dichloride and sulfur dioxide in the presence of azoisobutyronitrile. The structure and morphology of the polymer were characterized by using FTIR, TGA, EDX and SEM. The adsorption performance of the resin was evaluated using lead Pb(II) as a model. The effect of various parameters such as contact time, pH, initial concentration and temperature were investigated to arrive at optimum conditions. An optimum pH of 6.0 and dosage of 1.5 g L−1 were obtained. The mechanism of adsorption was investigated using kinetic, diffusion, isotherm and thermodynamic models. The adsorption kinetic data were described well by the pseudo-second order model with R2 of 0.999. The activation energy (Ea) of the adsorption process was calculated as 39.29 kJ mol−1. The negative ΔGo values indicate a spontaneous adsorption process while the negative ΔHo (−43.87 kJ mol−1) suggests an exothermic reaction. Adsorption data were described well by the Langmuir and Temkin models. EDX analysis confirmed the adsorption of Pb2+ on the polymer. The overall results suggest that the polymer could be employed as an efficient adsorbent for the adsorption of toxic Pb2+ from polluted aqueous solutions.

Evaluation of micro- and nano-carbon-based adsorbents for the removal of phenol from aqueous solutions

Abstract: This work reports on the adsorption efficiency of two classes of adsorbents: nano-adsorbents including carbon nanotubes (CNTs) and carbon nanofibers (CNFs); and micro-adsorbents including activated carbon (AC) and fly ash (FA). The materials were characterized by thermogravimetric analysis, transmission electron microscopy, Brunauer–Emmett–Teller (BET) specific surface area, zeta potential, field emission scanning electron microscopy, and UV spectroscopy. The adsorption experimental conditions such as pH of the solution, agitation speed, contact time, initial concentration of phenol, and adsorbent dosage were optimized for their influence on the phenol. The removal efficiency of the studied adsorbents has the following order: AC > CNTs > FA > CNFs. The capacity obtained from Langmuir isotherm was found to be 1.348, 1.098, 1.007, and 0.842 mg/g of AC, CNTs, FA, and CNFs, respectively, at 2 hours of contact time, pH 7, an adsorbent dosage of 50 mg, and a speed of 150 rpm. The higher adsorption of phenol on ...

Cross-linked diallyl quaternary ammonium salt tetrapolymers and methods thereof

Abstract: Cross-linked tetrapolymers made up of different diallyl zwitterionic diallyl quaternary ammonium salt monomers, with one of them functioning as a cross-linking monomer The cross-linked terpolymers include a repeating unit with multiple ligand centers that different metal ions can bind to The cross-linked tetrapolymers are cationic, zwitterionic and anionic, and can be in either an acidic form or a basic form A method of removing metal ions from an aqueous solution with these cross-linked tetrapolymers is also described

Cross-linked copolymers and methods thereof

Abstract: Cross-linked cyclocopolymers made up of one or more quaternary ammonium salts and sulfur dioxide as monomers. One of the quaternary ammonium salts is also an aspartic acid derivative. The cross-linked copolymers include a repeating unit with multiple chelating centers that different metal ions can bind to. The cross-linked copolymers are zwitterionic or anionic, and can be in either an acidic form or a basic form. A method for removing metal ions from an aqueous sample with these cross-linked copolymers is also described.