Removal of Tannery Dye from Aqueous Solution Using Papaya Seed as an Efficient Natural Biosorbent
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Removal of Tannery Dye from Aqueous Solution Using Papaya Seed as an Efficient Natural Biosorbent Caroline Trevisan Weber & Edson Luiz Foletto & Lucas Meili
Received: 18 August 2012 / Accepted: 18 December 2012 # Springer Science+Business Media Dordrecht 2013
Abstract Papaya seed was used as biosorbent for removal of tannery dye (Direct Black 38) from aqueous solution. The papaya seed was characterized, and it posseses macro/mesoporous texture, large pore size, and a surface containing various organic functional groups. The initial dye concentration, contact time, and pH significantly influenced the adsorption capacity. Equilibrium data were analyzed by the Langmuir and Freundlich isotherm models. The equilibrium data were best represented by the Langmuir isotherm, with a high adsorption capacity of 440 mgg−1. Adsorption kinetic data were fitted using the pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Boyd models. The adsorption kinetics for the dye onto papaya seed was best described by second-order kinetic equation. The adsorption process mechanism was found to be controlled by both external mass transfer and pore diffusion, but the external diffusion was the dominating process. Papaya seeds showed to be a promising material for adsorption of Direct Black 38 dye from aqueous solution. Keywords Papaya seed . Adsorption . Dye . Kinetic . Equilibrium . Mechanism
C. T. Weber : E. L. Foletto (*) : L. Meili Department of Chemical Engineering, Federal University of Santa Maria, 97105-900 Santa Maria, Brazil e-mail: [email protected]
1 Introduction A wide range of technologies has been employed for the treatment of dye wastewater such as flotation, filtration, biological treatment, coagulation–flotation, electrochemical process, adsorption, advanced oxidation process, and ion-exchange membrane (Shakir et al. 2010; Kariyajjanavar et al. 2011; Labanda et al. 2011; Foletto et al. 2012a, b; Collazzo et al. 2012a, b). Because of the high cost and disposal problems, many of these methods for treatment of dye wastewater have not been widely applied at large scale (Demirbas 2009). Among various methods, the adsorption process is one of the effective techniques that have been successfully employed for dye removal from wastewater, and activated carbon is the absorbent material most commonly applied for this purpose. Adsorption method offers significant advantages like the low cost, availability, profitability, ease of operation, and efficiency, in comparison with methods especially from economical and environmental points of view (Demirbas 2009). Adsorption also does not result in the formation of harmful substances (Crini 2006). However, the use of activated carbon as an adsorbent is disadvantageous because it is relatively expensive (Crini 2006), and, for this reason, a number of nonconventional low-cost materials have recently been tested and proposed as alternative absorbent to activated carbon for the removal of dyes from aqueous solutions. Adsorbent can be considered low-cost since it is abundant
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