Adsorption Characteristics of Mercury(II) Ions from Aqueous Solution

Jul 2, 2015 - The modified sorbent had good adsorption and desorption performance with respect to reusability after 10 repeated cycles. The thermodyna...
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Adsorption characteristics of mercury (II) ions from aqueous solution onto chitosan-coated diatomite Necmettin Caner, Ahmet SARI, and Mustafa Tuzen Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.5b01293 • Publication Date (Web): 02 Jul 2015 Downloaded from http://pubs.acs.org on July 7, 2015

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Industrial & Engineering Chemistry Research

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Adsorption characteristics of mercury (II) ions from aqueous solution onto chitosan-

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coated diatomite

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Necmettin Canera*, Ahmet Sarıb, Mustafa Tüzenb a

Department of Chemistry, Eskişehir Osmangazi University, 26480, Eskişehir, Turkey b Department of Chemistry, Gaziosmanpasa University, 60250, Tokat, Turkey

Abstract The prepared chitosan-coated diatomite (CCD) was characterized using FTIR spectroscopy

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and SEM techniques. The effects of pH, contact time, sorbent dosage, metal concentration,

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and temperature on the adsorption (%) of mercury (Hg(II)) from aqueous solution using the

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CCD sorbent were studied systemically. The monolayer sorption capacities of raw diatomite

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and CCD sorbents at pH 5 were found to be 68.1 and 116.2 mg/g, respectively. The mean

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adsorption energy (8.2 kJ/mol) calculated from the Dubinin–Radushkevich (D–R) model

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indicated that the sorption process occurred via chemisorption. The modified sorbent had

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good adsorption and desorption performance with respect to reusability after 10 repeated

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cycles. The thermodynamic calculations revealed that the sorption was viable, spontaneous

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and exothermic in nature under the conditions studied. The kinetic calculations indicated that

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the sorption mechanism was well explained by pseudo-second-order model. All results

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demonstrated that the prepared CCD is an effective sorbent for the removal of Hg(II) from

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aqueous solution.

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Keywords: Chitosan-coated diatomite, Mercury, Adsorption, Thermodynamics, Kinetics.

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*Corresponding author: Necmettin Caner; E-mail addresses: [email protected] (N. Caner)

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Industrial & Engineering Chemistry Research

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1. Introduction

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The water pollution resulted from the casual discharge of heavy metals has been causing

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global concerns for the last few decades. Some metals undoubtedly can have toxic effects on

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several types of living organisms.1

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Mercury found in the global environment has been widely known for centuries to be

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one of the most toxic heavy metals. This mercury is harmful to nature. Inhaled mercury vapor

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enters the blood stream via the lungs and spreads throughout the body. Symptoms of mercury

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poisoning are observed mainly in the form of neuronal disorders, but exposure to this metal

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will also damage the cardiovascular system, kidneys, liver, bones, etc.2-4 Three basic sources

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of mercury emissions are known: natural, anthropogenic and re-emitted sources.5 Controlling

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the concentrations of heavy metals in waste before it is discharge is therefore very important.

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Membrane separation, ion exchange, electrodeposition and chemical precipitation are among

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the most common methods for the elimination of heavy metals.6-8 However, these techniques

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are costly and especially ineffective for removing trace amounts of heavy metals.9 Another

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disadvantage of these methods is the formation of sludge, which requires the additional

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processes of disposal and confinement.10 The adsorption methods can be used to effectively

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remove contaminants from wastewater with high solute loadings, even at dilute

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concentrations (