Journal of Environmental Biology

Evaluation of adsorption potential of adsorbents: A case of uptake of cationic dyes

Nityanand Singh Maurya¹, Atul Kumar Mittal*¹ and Peter Cornel²

¹Environmental Engineering Laboratory, Department of Civil Engineering, Indian Institute of Technology Delhi,

Hauz Khas, New Delhi-110 016, India

²Institute WAR, Technische Universitat Darmstadt, Petersenstra?e-13, 64287, Darmstadt, Germany

(Received: April 13, 2006 ; Revised received: October 05, 2006 ; Accepted: November 13, 2006)

Abstract: Adsorption potential of a commercial activated carbon (FS300) has been evaluated for the uptake of cationic dyes namely methylene blue (MB) and rhodamine B (RB). Though, there are numerous studies in literature which report the sorption of MB (more than 40 studies) and RB (more than 10), however none of these use a common parameter to report the capacity of the sorbent. A protocol, based on the equilibrium dye concentration has been proposed to measure the sorption potential of a sorbent. The Langmuir model can very well describe the experimental equilibrium data for both dyes (coefficient of correlation > 0.999). MB (Q_m= 312.5 mg g^-1) is more adsorbable than the RB (Q_m = 144.9 mg g^-1). Molecular weight and chemical structure of dye molecules seem to affect the dye uptake. The effect of pH on dye uptake has also been evaluated by varying pH from 3 to 11. Uptake of MB increases with pH, wherein RB removal decreases with pH. Dyes could not be desorbed either by distilled water (0.06 and 0.11 % for MB and RB respectively) ,or by 0.1 N HCl (0.136 and 3.0% for MB and RB respectively) indicating, chemical adsorption type of adsorbent-adsorbate interactions.

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