Characteristics of cationic Red X-GRL biosorption by anaerobic activated sludge

Anaerobic activated sludge (AAS) was employed for the adsorption of cationic Red X-GRL (X-GRL) from aqueous solutions. The X-GRL uptakes decreased with increases in temperature and salinity, while it was improved with increase in pH. The adsorption of X-GRL by AAS had a better agreement with a fractal-like Langmuir isotherm than a typical Langmuir isotherm. The adsorption rate coefficients at different time had a power-law relationship with time. The surface dimension was positively related to the X-GRL uptakes. The X-GRL uptake by the EPS accounted for only similar to 19% of the total adsorption. The X-GRL adsorption was therefore largely attributed to the active groups on the cell wall. FTIR analysis showed that -CH2 and -NH2 groups were not responsible for the adsorption, which indicated chemical adsorption was negligible. (C) 2011 Elsevier Ltd. All rights reserved.