Effect of functional groups on sludge for biosorption of reactive dyes
CAI Junxiong , CUI Longzhe , WANG Yanxin , LIU Chengfu
DOI:
Received May 13, 2008,Revised June 27, 2008, Accepted , Available online
Volume 21,2009,Pages 534-538
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The sludge, which was collected from a biological coke wastewater treatment plant, was used as a low-cost adsorbent in the removal
of reactive dyes (Methylene Blue (MB) and Reactive Red 4 (RR4)) from aqueous solution. The pH of dye solution played an important
role on the dye uptake. With the solution pH increase, the MB uptake increased; whereas the RR4 uptake decreased. The maximum
uptake of RR4 by protonated sludge was 73.7 mg/g at pH 1, and the maximum uptake of MB by sludge was 235.3 mg/g at pH 9. Three
functional groups, including carboxyl, phosphonate, and amine group, were identified by potentiometric titration, fourier transform
infrared (FT-IR) spectrometry, and X-ray photoelectron spectroscopy (XPS). The anionic functional groups, phosphonate and carboxyl
group, were identified as the binding sites for the cationic MB. Amine groups were identified to bind RR4. The main mechanism of the
reactive dyestu s adsorption is electrostatic interaction.
