adsorption isotherms, kinetics, thermodynamics and desorption

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  • VOL. 6, NO. 11, NOVEMBER 2011 ISSN 1819-6608

    ARPN Journal of Engineering and Applied Sciences

    2006-2011 Asian Research Publishing Network (ARPN). All rights reserved.

    www.arpnjournals.com

    ADSORPTION ISOTHERMS, KINETICS, THERMODYNAMICS

    AND DESORPTION STUDIES OF REACTIVE ORANGE16 ON ACTIVATED CARBON DERIVED FROM

    Ananas comosus (L.) CARBON

    Parimalam Ramachandran1, Raj Vairamuthu2 and Sivakumar Ponnusamy31Department of Chemistry, Sri Meenakshi Government College for Women, Madurai, Tamil Nadu, India

    2Department of Chemistry, Periyar University, Salem, Tamil Nadu, India 3Department of Chemistry, Arignar Anna Government Arts College, Namakkal, Tamil Nadu, India

    E-Mail: pari_ramachandran@yahoo.co.in ABSTRACT

    The study describes the results of batch experiments on removal of reactive orange16 from aqueous solution onto activated carbon prepared from Ananas Comosus leaves. The adsorbent has been studied as a function of contact time, temperature, pH and initial dye concentration by batch experiments. The pH 2-3 was found suitable for maximum removal of RO16. A dye adsorption capacity of activated carbon for the RO16 is 147.05 mg/g of adsorbent. Langmuir, Freundlich, Tempkin, Dubinin-Raduskevich isotherm models were applied for the analysis of isotherm data. Thermodynamic treatment of adsorption data showed an exothermic nature of adsorption. The dye uptake process was found to follow second order kinetics. Keywords: reactive Orange16, Ananas comosus L., activated carbon, adsorption, kinetics. 1. INTRODUCTION

    Various industries such as dye manufacturing, pulp and paper, tanneries, cosmetics, coffee pulping pharmaceuticals, food processing, electro plating and distilleries spew out colored and toxic effluents to water bodies rendering them murky, dirty and unstable for further use. Among these industries, the textiles industries rank first in consume larger volumes of water and chemicals for the wet processing of textiles. Reactive dyes are extensively used in textile industry, which are usually characterized by nitrogen to nitrogen double bonds (N=N azo bonds). The color of the azo dye is due to this azo bond and the associated chromophores. The dyes are first adsorbed onto the cellulose and then react with the fiber. The reaction occurs by the formation of a covalent bond between the dye molecule and the fiber, which is much more resistant to unusual condition of use than the physic-chemical bond between other classes of dyes and cellulose (Al-Degs et al., 2000). These characteristics facilitate the interaction with the fiber and reduce energy consumption (Camp and Sturrock, 1990).

    The reactive system of these dyes react with ionized hydroxyl groups on the cellulose substrate but the hydroxyl ions present in the dye bath , due to the alkaline dyeing condition, compete with cellulose substrate, resulting in a percentage of hydrolyzed dyes no longer able to react with the fiber (Low et al., 2000). Thus approximately 10-50% of the initial dye load will be present in the dye bath, giving rise to a highly colored effluent (Easton, 1995). Reactive dyes are in general, the most problematic among other dyes, as they tend to pass through conventional treatment systems unaffected. Various physical, chemical and biological methods have been used for the treatment of dye containing wastewater. Some chemical oxidations, such as Fenton reagent, ozone, UV plus H2O2 or NaOCl, result in aromatic ring cleavage,

    which may generate chemical sludge or by-products that are likely to be even more toxic (Robinson. et al., 2001). Municipal aerobic treatment systems, dependent on biological activity were found to be ineffective in the removal of these dyes (Moran. et al., 1997) but anaerobic bioremediation enables water soluble dyes to be decolorized (Carliell. et al., 1996).

    Although ion exchange resins can be regenerated easily, the high cost hinders their wide application for the treatment of dye-bearing waste water. Consequently, various types of (bio) sorbents which are able to bind dye molecules and be easily regenerated have been extensively searched and tested (Robinson. et al., 2001 and Won. et al., 2004). Potential areas for practical application of sorbents are in the final decolorization of pretreated mixed waste water or dye removal from rinsing waters (after dyeing processes) for direct water recycling. A suitable sorbent has to meet the following criteria (Karcher. et al., 2001): (i) high affinity and capacity for target compounds, (ii) regeneration possible, (iii) safe and economically viable treatment/disposal of regenerate, (iv) tolerance for wide range of waste water parameters, and (v) usable for all or nearly all- reactive dyes.

    Among the various available water treatment technique adsorption is the most reliable and efficient technique for discoloration, in which the recovery and recycling of the adsorbent materials can be achieved along with the distinct advantages of non production of any toxic sludge cost effectiveness. This has encouraged the development of adsorbent that abundantly available and economical. Now a days numerous low cost adsorbents are available including products of agriculture origin such as wood dust, sugarcane, fruit peel (Senthilkumaar. et al., 2006), Wheat straw and apple pomance (Hana. et al., 2006). Certain other low cost adsorbent materials of industrial origin such as activated slag (Srivastava. et al.,

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  • VOL. 6, NO. 11, NOVEMBER 2011 ISSN 1819-6608

    ARPN Journal of Engineering and Applied Sciences

    2006-2011 Asian Research Publishing Network (ARPN). All rights reserved.

    www.arpnjournals.com

    1997), and bagasse fly ash (Gupta. et al., 1998), have also been employed in the recent past. Various types of sludge like waste works sludge, sewage sludge, digested sludge and leachate sludge (Sung Wook Won et al., 2006) and Zeolite from fly ash are employed to remove reactive orange dye (Denise Alves Fungaro et al., 2008).

    However, still there arises a great need to explore new low cost adsorbent materials with high adsorption capacity. Thus in the present study, keeping the toxic effect in view, attempts have been made to develop an efficient and cost effective technique for the removal of dye from waste water by employing carbon from waste material namely Ananas comosus leaves which is easily and abundantly available. The characterization of this carbon is done by X-ray diffraction (XRD) and BET surface area analysis, FT-IR Spectral and SEM analysis. Influence of temperature, pH of the dye solution, effect of contact time and initial dye concentration are studied under stirred condition. Thermodynamic parameters are calculated to know the nature of adsorption. Four different kinetic models for the adsorption of dye are presented. The equilibrium data are tested with Langmuir, Freundlich, Tempkin, Dubinin-Raduskevich isotherm models. This fundamental study will be helpful for further application in designing a batch adsorption for the treatment of dye containing effluent coming out from dye industries. 2. MATERIALS AND METHODS 2.1 Adsorbate

    All chemicals used in this study were of analytical grade. Reactive Orange 16 (RO 16) having molecular formula C20H17N3O11S3Na2 (Mol. Wt: 617.53, max = 496) with CI. No.17757, (E. Merck, India) was used as a model reactive dye in this work. As shown in Figure-1, RO16 has two sulfonate groups which have negative charges in aqueous solution (Figure-1).

    Figure-1. Structure of reactive orange 16. 2.2 Preparation of adsorbent (ACC)

    Raw material (Ananas comosus leaves) used for the preparation of activated carbon was collected locally, cut into pieces of 1cm to 2cm size, dried in sunlight for 7 days. The dried material soaked in a boiling solution of 10% H3PO4 for 1h and kept at room temperature for overnight, then the material were separated, air dried and carbonized in muffle furnace at 400oC for 20 min. The carbonized material was powdered, activated in a muffle furnace at 600oC for a period of 10 min. Then the material

    was washed with plenty of distilled water to remove residual acid, dried, sieved 45 m to 300 m size and stored in a tight lid container for further adsorption studies (Table.1). 2.3 Characterization

    X-ray diffraction patterns of the activated carbon sample were studied using DELL GX 270 and the patterns were recorded over a 2-theta (2) range of 10-75. The FT-IR spectra of the activated carbon sample were scanned by placing KBr pellets in the Parkin Elmer 16 PC spectrometer. The KBr pellets were prepared by mixing the carbon samples with KBr powder, grounding it in an agate mortar and then shaping it into pellets under hydraulic pressure. SEM photograph of the carbon sample were examined by scanning electron microscope (Hitachi S-3400N). 2.4 Adsorption studies

    Adsorption characteristics were determined with the help of primary analysis. To study the effect of important parameters such as effect of initial concentration, pH, agitation time, temperature, batch studies were performed by taking 100ml of dye solution in 250ml volumetric flasks at 30, 40, and 50 C. 100mg of suitable mesh size activated carbon was chosen and added into each flask with intermittent shaking. The mixture was withdrawn at specified interval then centrifuged using electrical centrifuge (Universal make) at 3000 rpm for 10 minutes and unabsorbed supernatant liquid was analyzed for the residual dye concentration using Elico make Bio-UV

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