Publications by authors named "Ahmed A Abdeltawab"

5 Publications

  • Page 1 of 1

Phosphonium-based Ionic Liquid Modified Activated Carbon from Mixed Recyclable Waste for Mercury(II) Uptake.

Molecules 2019 Feb 5;24(3). Epub 2019 Feb 5.

Advanced Materials Research Chair, Chemistry Department P. O. Box 2455, College of Science, King Saud University, Riyadh 11451, Saudi Arabia.

The contamination of water surfaces by mercury is a dangerous environmental problem due to its toxicity, which leads kidney damage. Activated carbon from mixed recyclable waste modified by phosphonium-based ionic liquid (IL-ACMRW) was therefore prepared and evaluated for Hg(II) remediation. The activated carbon used in this study was prepared from mixed waste, including cardboard, papers and palm wastes as cheap raw materials. The mixed Recyclable Waste Activated Carbon was combined with trihexyl(tetradecyl)phosphonium Bis2,4,4-(trimethylpentyl)phosphinate (Cyphos IL 104) ionic liquid to form an adsorbent with organic-inorganic content, in order to improve the Hg(II) uptake from aqueous solutions. FTIR confirms the presence of P, C=O and OH after this modification. The adsorption process was investigated and the evaluated results showed that the capacity was 124 mg/g at pH 4, with a contact time of 90 min, an adsorbent dose of 0.4 g/L, and a Hg(II) concentration of 50 mg/L. This Hg(II) adsorption capacity is superior than that reported in the literature for modified multiwall carbon nanotubes. The adsorption of Hg(II) on the modified activated carbon from mixed recyclable waste was found to follow the pseudo second-order kinetics model. Isotherms of adsorption were analyzed via Freundlich and Langmuir models. The results indicated that Freundlich is the best model to describe the process, suggesting multilayer adsorption.
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http://dx.doi.org/10.3390/molecules24030570DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6384760PMC
February 2019

Pretreatment of wheat straw using basic ethanolamine-based deep eutectic solvents for improving enzymatic hydrolysis.

Bioresour Technol 2018 Sep 4;263:325-333. Epub 2018 May 4.

Beijing Key Laboratory of Membrane Science and Technology & College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China. Electronic address:

A series of ethanolamine based deep eutectic solvents (DESs), which have strong basicity, were firstly applied in wheat straw pretreatment. Typically, choline chloride: monoethanolamine (C:M) as the best solvent among these DESs can remove 71.4% lignin and reserve 93.7% cellulose (70 °C, L/S mass ratio of 20:1, 9 h), and improve the enzymatic hydrolysis of residue, i.e., 89.8% cellulose and 62.0% xylan conversion. The pretreatment capacity of C:M is comparable to other solvents while C:M has several advantages, e.g., lower cost with cheap materials and simpler preparation process, mild conditions and lower polysaccharide loss. The XRD, SEM and FT-IR results verified that the polysaccharide conversion and sugars yield were enhanced by the removal of lignin in the pretreatment process. The basic ethanolamine based DESs are promising solvents for industrial application of wheat straw pretreatment.
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http://dx.doi.org/10.1016/j.biortech.2018.05.016DOI Listing
September 2018

Cholinium amino acids-glycerol mixtures: New class of solvents for pretreating wheat straw to facilitate enzymatic hydrolysis.

Bioresour Technol 2017 Dec 4;245(Pt A):625-632. Epub 2017 Sep 4.

Beijing Key Laboratory of Membrane Science and Technology & College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China. Electronic address:

New solvents for pretreating wheat straw, mixtures of cholinium amino acids ionic liquids ([Ch][AA] ILs) and glycerol, were developed. As a typical result, 50% cholinium alanine-glycerol is capable of removing 67.6% lignin while reserving 95.1% cellulose (90°C, L/S mass ratio of 20:1, 6h) and the conversions of cellulose and xylan are 89.7% and 70.9%, respectively, which is comparable to the pretreatment capability of other solvents, while [Ch][AA]-glycerol mixtures have desirable advantages, e.g., biocompatibility, lower cost with adding glycerol than pure IL, much lower pretreatment temperature (typically <100°C) than that by glycerol (typically >200°C). Lignin removal and polysaccharide conversion are dependent on [Ch][AA] content and pH of pretreatment solvents. [Ch][AA] not only remove lignin in wheat straw effectively but also swell cellulose while not remarkably dissolve cellulose with high cellulose reservation, favoring the enzymatic hydrolysis. Such mixtures of ILs and co-solvents are potential solvents for pretreating biomass.
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http://dx.doi.org/10.1016/j.biortech.2017.08.209DOI Listing
December 2017

Elimination of the azeotropic point of acetone and methanol by 1,3-dimethylimidazolium dimethylphosphate: an ab initio calculation study.

J Mol Model 2017 Mar 15;23(3):74. Epub 2017 Feb 15.

Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.

1,3-Dimethylimidazolium dimethylphosphate ([Cmim][DMP]) was observed experimentally to be able to eliminate the atmospheric azeotropic point of acetone and methanol, which is an important azeotrope generally encountered in furfural production and the Fischer-Tropsch process. Here, we employed ab initio calculation to understand the underlying mechanism of [Cmim][DMP] in eliminating the azeotropic point of acetone and methanol. Structure, energy and interaction in binary-, ternary- and quaternary-clusters composed of methanol, acetone, [Cmim] or/and [DMP]‾ were calculated. The σ-hole, AIM and NBO analyses were performed to understand intermolecular interaction with electron density, electron occupancy, charge transfer and molecular orbital interaction. Hydrogen bond interaction plays a key role in azeotropic point elimination; due to the much stronger hydrogen bond interaction between methanol and [Cmim][DMP] than that between acetone and [Cmim][DMP], [Cmim][DMP] prefers to interact with methanol rather than acetone, and the original interaction between methanol and acetone is separated by [Cmim][DMP]. The hydrogen bond is from the orbital interaction between O lone-pair-electron orbitals of the hydrogen bond acceptor and σ * (C-H) or σ * (O-H) anti-bonding orbitals of the hydrogen bond donor, where remarkable electron or charge transfer occurs. These theoretical calculation results are in agreement with the experimental observation that [Cmim][DMP] eliminates the azeotropic point of methanol and acetone. This work shows that ab initio calculation may be employed to rationalize the design or synthesis of ionic liquids for separating azeotropes. Graphical Abstract Elimination of azeotropic point of acetone and methanol by [Cmim][DMP].
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http://dx.doi.org/10.1007/s00894-017-3218-yDOI Listing
March 2017

Computational fluid dynamics study on mixing mode and power consumption in anaerobic mono- and co-digestion.

Bioresour Technol 2016 Mar 15;203:166-72. Epub 2015 Dec 15.

Beijing Key Laboratory of Membrane Science and Technology & College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China. Electronic address:

Computational fluid dynamics (CFD) was applied to investigate mixing mode and power consumption in anaerobic mono- and co-digestion. Cattle manure (CM) and corn stover (CS) were used as feedstock and stirred tank reactor (STR) was used as digester. Power numbers obtained by the CFD simulation were compared with those from the experimental correlation. Results showed that the standard k-ε model was more appropriate than other turbulence models. A new index, net power production instead of gas production, was proposed to optimize feedstock ratio for anaerobic co-digestion. Results showed that flow field and power consumption were significantly changed in co-digestion of CM and CS compared with those in mono-digestion of either CM or CS. For different mixing modes, the optimum feedstock ratio for co-digestion changed with net power production. The best option of CM/CS ratio for continuous mixing, intermittent mixing I, and intermittent mixing II were 1:1, 1:1 and 1:3, respectively.
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http://dx.doi.org/10.1016/j.biortech.2015.12.023DOI Listing
March 2016
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