Removal of azo dyes from aqueous solutions by adsorption and electrosorption as monitored with in-situ UV-visible spectroscopy

ABSTRACT

Removal of three azo dyes, Acid Orange 8, Acid Yellow 14 and Acid Red 151 from aqueous solutions was investigated by adsorption and electrosorption techniques. The processes were monitored by in-situ UV-visible absorbance measurements. Activated carbon cloth (ACC) was used as an adsorbent in open circuit adsorption studies and as a working electrode in electrosorption studies. Electrosorption was seen to enhance the removal of dyes both in amount and in speed compared to adsorption. Kinetic data fitted to pseudo-second-order model better than pseudo-first-order model. Isotherm data fitted to the Freundlich model better than the Langmuir model.

KEYWORDS:

• Azo dye
• adsorption
• electrosorption
• activated carbon cloth
• in-situ UV-visible spectroscopy