Abstract
In recent years, dyes pollution has become one of the most serious environmental problems. Biosorption as a biotechnology for removal of dyes pollution from aqueous solutions has been extensively studied and most biosorption research mainly focused on the process kinetics and thermodynamics. Bacterial cellulose is receiving great attention and presently being widely investigated as a new type of cost-efficient biosorbent due to its nanofibers network, biocompatibility, nontoxicity, biodegradability and high water holding capacity. The aim of this study was to determine the thermodynamic and kinetic adsorption of direct blue 15 dye from aqueous solutions with bacterial cellulose as a biosorbent. The effects of pH, contact time and temperature on adsorption of direct dye by bacterial cellulose were also evaluated. Kinetic study of direct blue 15 on bacterial cellulose, were carried out under sorption conditions of pH 3.0, MLR 1:500 and an initial dye concentration 100 mg/L. Kinetic analyses were conducted using pseudo first- and second-order models. The regression results showed that the adsorption kinetic was more accurately represented by a pseudo second-order model. Changes in free energy of adsorption (ΔG#), enthalpy (ΔH#) and entropy (ΔS#) as well as the activation energy (Ea) were determined. ΔH#, ΔS# and Ea with pH control were -26.5, -230 and 43.5 kJ/mol. The result showed that the bacterial cellulose could be employed as an effective sorbent for the removal of direct dye from aqueous solution and the values of ΔH#, ΔG# and Eaindicate that the adsorption of direct dye onto bacterial cellulose was a physisorption process. Key words: Acetobacter xylinum, biosorbent, kinetic, thermodynamic, bacterial cellulose
Highlights
Dyes are widely used in industries, such as textiles, paper, plastics and leather, etc., for the coloration of products
The result showed that the bacterial cellulose could be employed as an effective sorbent for the removal of direct dye from aqueous solution and the values of ∆H#, ∆G# and Ea indicate that the adsorption of direct dye onto bacterial cellulose was a physisorption process
These results suggested that the experimental data for the adsorption kinetics of dye on Bacterial cellulose (BC) were fitted by the pseudo second-order kinetic model
Summary
Dyes are widely used in industries, such as textiles, paper, plastics and leather, etc., for the coloration of products. The high cost of removal of dyes from aqueous solutions using adsorption on commercial activated carbons though very effective has motivated the search for alternatives adsorbents. Such alternatives include: waste metal hydroxide sludge (Santos et al, 2008), oil palm trunk fibre (Hameed and El-Khaiary, 2008a), broad bean peels (Hameed and El-Khaiary, 2008c), biomass fly ash (Pengthamkeerati et al, 2008), rice straw-derived char (Hameed and El-Khaiary, 2008b), durian (Durio zibethinus Murray) peel (Hameed and Hakimi, 2008), chitosan bead (Bekc et al, 2008), rice husk (Han et al, 2008) and palm kernel fibre (Augustine and Yuh-Shan, 2007). Of the different biological methods, bioaccumulation and biosorption have been demonstrated to possess good potential to replace conventional methods for the removal of dyes (Volesky et al, 2003)
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