Chemistry / Kimya

Permanent URI for this collectionhttps://hdl.handle.net/11147/4072

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Author: search.filters.author.Shahwan, TalalInstitution Author: search.filters.institutionAuthor.Demir, Mustafa Muammer

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Now showing 1 - 3 of 3
  • Article
    Citation - WoS: 109
    Citation - Scopus: 119
    Synthesis of Amidoximated Polyacrylonitrile Fibers and Its Application for Sorption of Aqueous Uranyl Ions Under Continuous Flow
    (Elsevier Ltd., 2012) Horzum Polat, Nesrin; Shahwan, Talal; Parlak, Onur; Demir, Mustafa Muammer
    This study reports a feasible method for the removal of radioactive U(VI) ions from aqueous systems via column sorption under continuous flow. Electrospun polyacrylonitrile (PAN) fibers were used as sorbent materials in a homemade minicolumn. The nitrile groups on the fibers' surface were modified to amidoxime groups using hydroxylamine hydrochloride. Surface modification was observed to enhance the sorption capacity of PAN fibers toward uranium ions by more than 4-fold by virtue of the chelating ability of the amidoxime groups. The experiments investigated the effect of pH, initial concentration, and repetitive loading on the sorption properties of amidoximated PAN fibers. Based on the overall results, the surface-modified fibers seem to be a suitable potential sorbent material for applications in environmental cleanup, particularly for nuclear plants.
  • Article
    Citation - WoS: 109
    Citation - Scopus: 124
    Chitosan Fiber-Supported Zero-Valent Iron Nanoparticles as a Novel Sorbent for Sequestration of Inorganic Arsenic
    (Royal Society of Chemistry, 2013) Horzum Polat, Nesrin; Demir, Mustafa Muammer; Nairat, Muath; Shahwan, Talal
    This study proposes a new sorbent for the removal of inorganic arsenic from aqueous solutions. Monodispersed nano zero-valent iron (nZVI) particles were nucleated at the surface of electrospun chitosan fibers (average fiber diameter of 195 ± 50 nm) by liquid phase reduction of FeCl3 using NaBH4. The material was characterized using SEM, TGA, XPS, XRD, and FTIR. The diameter of iron nanoparticles was found to vary between 75-100 nm. A set of batch experiments were carried out to elucidate the efficiency of the composite sorbent toward fixation of arsenite and arsenate ions. The ion concentrations in the supernatant solutions were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The results revealed that the chitosan fiber supported nZVI particles is an excellent sorbent material for inorganic arsenic uptake at concentrations ranging from 0.01 to 5.00 mg L -1 over a wide range of pH values. Based on XPS analysis, As(iii) was found to undergo oxidation to As(v) upon sorption, while As(v) retained its oxidation state. By virtue of the successful combination of the electrospun fibers' mechanical integrity and the large reactivity of dispersed nZVI particles, the applicability of the resulting sorbent material in arsenic sorption holds broad promise.
  • Article
    Citation - WoS: 70
    Citation - Scopus: 82
    Sorption Efficiency of Chitosan Nanofibers Toward Metal Ions at Low Concentrations
    (American Chemical Society, 2010) Horzum Polat, Nesrin; Boyacı, Ezel; Eroğlu, Ahmet Emin; Shahwan, Talal; Demir, Mustafa Muammer
    Chitosan fibers showing narrow diameter distribution with a mean of 42 nm were produced by electrospinning and utilized for the sorption of Fe(III), Cu(II), Ag(I), and Cd(II) ions from aqueous solutions. The ion concentrations in the supernatant solutions were determined using inductively coupled plasma-mass spectrometry (ICP-MS). The filtration efficiency of the fibers toward these ions was studied by both batch and microcolumn methods. High efficiency in sorption of the metal ions was obtained in the both methods. The effects of sorbent amount (0.10−0.50 mg), shaking time (15−120 min), initial metal ion concentration (10.0−1000.0 μg·L−1), and temperature (25 and 50 °C) on the extent of sorption were examined. The sorbent amount did not significantly alter the efficiency of sorption; however, shaking time, temperature, and metal ion concentration were found to have a strong influence on sorption. By virtue of its mechanical integrity, the applicability of the chitosan mat in solid phase extraction under continuous flow looks promising.