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Shawky H.A.,Duke University | Shawky H.A.,Water Treatment and Desalination Unit | Chae S.-R.,University of Sydney | Lin S.,Duke University | Wiesner M.R.,Duke University
Desalination | Year: 2011

Multi-wall carbon nanotube (MWCNT)/aromatic polyamide (PA) nanocomposite membranes were synthesized by a polymer grafting process. Surface morphology, roughness, and mechanical strength of the resultant nanocomposite membranes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and micro-strain analysis, respectively. SEM and AFM images showed that MWCNTs were well dispersed in the PA matrix. Measurements of mechanical properties of this composite showed increasing membrane strength with increasing MWCNT content with monotonic increases in Young's modulus, toughness, and tensile strength. The addition of MWCNTs also improved the rejection of both salt and organic matter relative to the 10% PA membrane base case. The nanocomposite membrane synthesized with 15. mg/g MWCNT in a 10% PA casting solution rejected NaCl and humic acid by factors of 3.17 and 1.67 respectively relative to the PA membrane without MWCNTs, while membrane permeability decreased by 6.5%. © 2010 Elsevier B.V. Source

Shawky H.A.,Water Treatment and Desalination Unit
Journal of Applied Polymer Science | Year: 2011

The aim of this study is to explore naturally occurring sorbents that have high affinity for heavy metal treatment. In this respect, series of polymer-clay composite beads that consists of Na-alginate and montmorillonite clay were prepared using CaCl2 as crosslinker. The prepared composite bead was characterized by scanning electron microscope (SEM). Removal of lead from aqueous solution using this bead was then studied in batch adsorption experiments. The amount of lead removed was found to increase as the percent of Na-alginate increase in the composite beads. The experimental results also showed that the equilibrium contact time was obtained within ∼ 100 min with (t1/2) of 50% adsorption in less than 10 min. Lead adsorption was found to be strongly pH-dependent and display a maximum uptake capacity (244.6 mg/g) at pH 6 and minimum uptake (76.6 mg/g) at pH 1. Maximum lead adsorption was found to increase with increasing initial lead concentration in the feed solution and with decreasing temperature of experiment. Based on alginate-montmorillonite beads packed columns, a highly efficient method for Pb(II) removal from aqueous solution was developed. The effect of flow rate on adsorption of 100 mg/L Pb(II) in the packed-bed column was investigated by changing the flow rate between 0.5 and 2.5 mL min-1. The recovery of 100 mg/L Pb(II) in the packed-bed column was found to be 100% at flow rates 0.5 and 1 mL min-1 then lowered to be 93% and 84% at flow rates 1.5 and 2.5 mL min-1, respectively. The effect of Pb(II) flow concentration ranging from 10 to 1000 mg/L on the adsorption of lead ions at constant flow rate 1.0 mL min-1 was also studied using column procedure. Technical feasibility for the uses of the prepared composite beads for the treatment of actual polluted wastewater samples collected from some industrial cities in Egypt was investigated. The evaluation of the system was performed by a complete analysis of heavy metals in the wastewater samples before and after the treatment process. The results showed a promising possibility for producing wastewater of better quality using such prepared beads. © 2010 Wiley Periodicals, Inc. Source

Said M.M.,Water Treatment and Desalination Unit | El-Aassar A.H.M.,Water Treatment and Desalination Unit | Kotp Y.H.,Water Treatment and Desalination Unit | Shawky H.A.,Water Treatment and Desalination Unit | And 2 more authors.
Desalination and Water Treatment | Year: 2013

This study aims to enhance the performance of the flat sheet thin-film composite (TFC) polyamide-polysulfone reverse osmosis (RO) membranes. Composite RO membranes with high salt rejection were fabricated by treating a porous polysulfone (PS) support sequentially with a di-amine and then with a polyfunctional acid chloride, thereby forming a thin film of polyamide (PA) on the PS support. In order to establish conditions for the development of suitable thin-film composite (PS/TFC) membranes, various parametric studies were carried out which included varying the concentration of reactants, reaction time, curing temperature, and curing time for thin-film formation by the interfacial polymerization technique. By suitable combination of these factors, 2.0 wt.% MPD, 0.5 wt.% TMC, 60-s reaction time, 80°C curing temperature, and curing time 10 min., a desired thin film of PA with improved performance for groundwater desalination could be obtained. Further, a combination of scanning electron microscopy (SEM), attenuated total reflectance infrared (ATR-IR), X-ray diffraction (XRD) was utilized to confirm the existence and to examine the morphology of the PS/TFC membrane. Pilot-scale RO filtration unit was used to study the performance of the fabricated membranes for desalinating brackish, saline groundwater of Red Sea coastal area. Salt rejections percent for various feeds were found to be in the range of 90.6-98.5. © 2013 Copyright Balaban Desalination Publications. Source

Shawky H.A.,Water Treatment and Desalination Unit | Shawky H.A.,Nile University | El-Aassar A.H.M.,Water Treatment and Desalination Unit | Abo-Zeid D.E.,Desert Research Center
Journal of Applied Polymer Science | Year: 2012

Composite beads composed of chitosan (CS) with different carbon nanotubes (CNTs) were prepared by the incorporation of single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), and carboxylic multiwalled carbon nanotubes (MWCNT-COOHs). A protected crosslinking method was used for the preparation of the CS/CNTs beads by the reaction of the beads with Hg(II) as the protector. Scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis were used to characterize the prepared beads. The adsorption performance of the prepared beads was investigated for the removal of Hg(II). The results show that beads prepared by the protected crosslinking technique removed 2.5 times more Hg(II) from solution than beads prepared by normal crosslinking. The maximum Hg(II) removal values were 148.7, 183.2, 167.5, and 172.7 mg/g by CS, MWCNT-COOH-impregnated CS beads, MWCNT-impregnated CS beads, and SWCNT-impregnated CS composite beads, respectively. The optimum removal conditions were pH = 4, contact time = 40 min, and temperature = 70°C. The equilibrium adsorption isotherm data of the beads exhibited a better fit to the Langmuir isotherm model. The reusability of Hg(II) sorption by the prepared beads was investigated to evaluate their repeated availability performance in water treatment. Quantitative removal of mercury from industrial wastes was demonstrated. A statistical analysis of the replacement cost of these sorbents revealed that SWCNTs, MWCNTs, and MWCNT-COOH could possibly be cost-effective sorbents in water treatment, regardless of their high unit cost at this time. © 2011 Wiley Periodicals, Inc. Source

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