Search for: hexavalent-chromium
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    Hybrid nano-adsorbent supported carbon dots for removal of chromium from aqueous solution

    , Article Desalination and Water Treatment ; Volume 103 , 2018 , Pages 221-231 ; 19443994 (ISSN) Eslami, A ; Borghei, S. M ; Rashidi, A ; Takdastan, A ; Sharif University of Technology
    Desalination Publications  2018
    In this study, hybrid nano adsorbent supported carbon dots was prepared and used for removing Cr(VI) from aqueous solution. Carbon dots were synthesized from sugarcane molasses under microwave irradiation. Hybrid nano adsorbent was prepared by impregnating carbon dot with H3PO4 in a ratio of 2:1 and introducing 0.01 M FeCl3 into the slurry. The carbon dot hybrid was activated via a conventional thermal method under N2 flow. The physico-chemical properties of the synthesized material were investigated using X–ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption, and field emission scanning electron microscopy (FESEM). Chromium adsorption was studied... 

    Effects of Additives on Chromium Coating in Trivalent Chromium Bath

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Ghasem (Author) ; Dolati, Abolghasem (Supervisor)
    In this work, effects of different additives on trivalent Chromium bath and Chromium coating has been investigated. Malonic acid wich had been used as a complexing agent of the bath improved current efficiancy and coating quality obviously. Effects of Magnesum, zinc, Tin, Aluminium sulfates, Molybdic acid, TiO2 nano particles, Sodium hypophospite, formaldehead and mixtures of these compositions on hexavalent Chromium concentration of the bath were also studied. Concentration of Cr6+ ion decreased by 18 ppm due to adding these materials. Using Ti/ TiO2/ RuO2 Anode also could decrease Cr6+ concentration by 78 ppm. Remarkable results had been recorded in current efficiency and coating... 

    Gold, Palladium and Gold-Palladium Nanoparticles Electrodes Electrodeposited on Indium Tin Oxide and Titanium Oxide for Direct Determination and Reduction of Hexavalent Chromium

    , Ph.D. Dissertation Sharif University of Technology Siavash Moakhar, Roozbeh (Author) ; Dolati, Abolghasem (Supervisor) ; Ghorbani, Mohammad (Supervisor)
    Hexavalent chromium ions (Cr(VI)) is one of the most dangerous heavy ions for the environment, humans and other living organisms. Hence, finding new ways to determine and reduction to the much less toxic trivalent chromium (Cr(III)) is highly important. In this thesis, electrochemical and photoelectrochemical methods have been employed for the direct detection and reduction of Cr (VI). For this purpose, the indium tin oxide (ITO) electrode decorated with gold-palladium bimetallic nanoparticles (AuPd) was used for the determination and reduction of Cr(VI) via electrochemical route. These AuPd decorated electrodes exhibited a wide linear concentration range of 0.001-100 µM, a very low... 

    Development of Polymerization Method to Produce Spherical Polymer Particles with Nanoscale Porosity in Packed Beds

    , M.Sc. Thesis Sharif University of Technology Karimi, Mehdi (Author) ; Shojaei, Akbar (Supervisor) ; Abd Khodaei, Mohammad Jafar (Supervisor) ; Nematollah Zadeh, Ali (Co-Advisor)
    Porous polymeric particles have the extensive application in various sciences and various methods have been introduced for production of these particles. Depending on method of production, porous polymeric beads can be produced in diverse shapes, pore size, pores interconectivity, surface morphology and chemical properties. In common methods for production of porous polymeric particles, tuning the size and porosity is difficult or even impossible. Porous polymeric beads with the vast surface area and good functionality have been applied for adsorption of various materials. The purpose of this study is therefore to investigate a new procedure for the production of porous polymeric... 

    Pulse Electrodeposition of Chromium Coating From Trivalent Bath and Studying it’s Properties

    , M.Sc. Thesis Sharif University of Technology Araban, Vahid (Author) ; Ghorbani, Mohammad (Supervisor) ; Dolati, Abolghasem (Supervisor)
    Trivalent chromium plating has been known as a very promising technology to replace hexavalent chromium which is so toxic. The coatings obtained from tivalent chromium baths have lower thickness and Hardness and higher corrosion rate in comparison with deposits obtained from hexavalent chromium baths.A few studies on pulse plating of trivalent chromium as an effective way to enhance the coating properties have been published.
    In this research glycine was chosen as complexing agent.The results have shown that in pulse plating at 1 Hz, Duty cycle 50%, peak current density 0/2 A/Cm2 and after 30 minutes, thickness achieves 13 µm which is much greater in comparison with coatings obtained in... 

    Synthesis and Characterization of a Composite of ZIF-8 and TiO2 NPs as a Photocatalyst Material for Water Treatment

    , M.Sc. Thesis Sharif University of Technology Sedighi, Omid (Author) ; Dolati, Abolghasem (Supervisor) ; Abachi, Parvin (Supervisor)
    During the past few years, hexavalent chromium (Cr(VI)) is of environmental concern due to its high toxicity and mobility. Therefore, removing it from industrial wastewater is of chief significance. In this research, efficient photocatalyst materials (xµLTiO2NPs@ZIF-8) for the reduction of Cr(VI) from water resources were firstly synthesized. This composite was prepared by an in situ method with zeolitic imidazolate framework-8 as the matrix. TiO2 and ZIF-8 were selected for their excellent stability in aqueous media, high photoactivity, non-toxicity, and high surface area. The structure of the as-synthesized materials was characterized by X-ray powder diffraction (XRD), scanning electron... 

    A novel screen-printed TiO2 photoelectrochemical sensor for direct determination and reduction of hexavalent chromium

    , Article Electrochemistry Communications ; Volume 61 , 2015 , Pages 110-113 ; 13882481 (ISSN) Siavash Moakhar, R ; Goh, G. K. L ; Dolati, A ; Ghorbani, M ; Sharif University of Technology
    Elsevier Inc  2015
    A novel and simple photoelectrochemical (PEC) sensor to detect Cr(VI) based on screen-printed TiO2 modified with gold nanoparticles is presented. The proposed PEC sensor showed a very low detection limit (S/N = 3) of 0.004 μM, over a wide linear concentration range from 0.01 μM to 100 μM with a high sensitivity of 11.88 μA.μM-1 Cr(VI). Results also indicated good anti-interference and superb recovery in natural media application for Cr(VI) sensing  

    Nano-scale modification of polysulfone membrane matrix and the surface for the separation of chromium ions from water

    , Article Chemical Engineering Journal ; Volume 267 , May , 2015 , Pages 306-316 ; 13858947 (ISSN) Habibi, S ; Nematollahzadeh, A ; Mousavi, S. A ; Sharif University of Technology
    Elsevier  2015
    In this study, aiming at hexavalent chromium removal from aqueous solutions, different strategies were proposed for developing hydrophilic and surface functional polysulfone (PSf) membrane. In addition to PSf membrane, three different types of membranes were prepared by addition of SiO2 nano-particles to the dope solution and/or by deposition of polydopamine (PDA) layer on the surface of the membranes. The membranes (i.e. PSf, PSf/PDA, PSf/SiO2 and PSf/SiO2/PDA) were characterized by different techniques. The membranes' transport properties and the separation performance were studied using a filtration unit operated at a continuous dead-end flow mode. The kinetics and the separation... 

    Au-Pd bimetallic nanoparticle electrodes for direct electroreduction of hexavalent chromium complexes

    , Article Australian Journal of Chemistry ; Volume 69, Issue 4 , 2016 , Pages 423-430 ; 00049425 (ISSN) Moakhar, R. S ; Hariri, M. B ; Kushwaha, A ; Dolati, A ; Ghorbani, M ; Goh, G. K. L ; Sharif University of Technology
    CSIRO  2016
    This paper reports a simple, low-cost, and effective electrochemical technique for sensing and reducing CrVI based on a Au-Pd bimetallic nanoparticle (BNP)-decorated indium tin oxide (ITO) conducting glass electrode. It was observed that the Au-Pd BNP-decorated ITO electrode could significantly boost the electrochemical reduction of CrVI when compared with either Au nanoparticle- or Pd nanoparticle-decorated ITO electrodes. These BNP-decorated electrodes exhibited a wide linear concentration range of 0.001-100 μM, a very low detection limit (signal-to-noise ratio = 3) of 0.3 nM, and a high sensitivity of 1.701 μA μM-1. From electrochemical impedance spectroscopy, it was revealed that this... 

    Sunlight-driven photoelectrochemical sensor for direct determination of hexavalent chromium based on Au decorated rutile TiO2 nanorods

    , Article Applied Catalysis B: Environmental ; Volume 201 , 2017 , Pages 411-418 ; 09263373 (ISSN) Siavash Moakhar, R ; Goh, G. K. L ; Dolati, A ; Ghorbani, M ; Sharif University of Technology
    Elsevier B.V  2017
    A highly sensitive and selective sunlight-driven photoelectrochemical sensor for the direct detection and reduction of chromium(VI) was developed based on single crystal rutile titanium dioxide nanorods decorated with gold nanoparticles. Under sun simulator illumination via the amperometric technique, these Au decorated TiO2 photoelectrodes exhibited the highest sensitivity (13.94 μA μM−1) ever reported among Au-based electrodes for Cr(VI) detection, with a very low detection limit (S/N = 3) of 0.006 μM and wide linear concentration range from 0.01 μM to 50 μM. Measurements in real water samples such as laboratory and river water also showed excellent anti-interference and recovery... 

    Removal of chromium from aqueous solution using polyaniline - Poly ethylene glycol composite

    , Article Journal of Hazardous Materials ; Volume 184, Issue 1-3 , December , 2010 , Pages 248-254 ; 03043894 (ISSN) Riahi Samani, M ; Borghei, S. M ; Olad, A ; Chaichi, M. J ; Sharif University of Technology
    The adsorption of chromium compounds from solutions by a composite of polyaniline/poly ethylene glycol (PANi/PEG) was investigated in this study. Experiments were conducted in batch mode under various operational conditions including agitation time, solution pH, PANi/PEG dose and initial concentration of chromium salts. Results showed that concentration of PEG at synthesizing stage has a significant effect on the capacity of produced composite for removal of chromium. Morphologically, PANi/PEG composite is closely dependent on the concentration of PEG. Maximum removal of hexavalent chromium was experienced when 2. g/L of PEG was used in synthesis of PANi/PEG. Removal of hexavalent chromium...