Contribution of extracellular polymeric substances fractions to the adsorption of silver nanoparticles by activated sludge. Issue 5 (October 2022)

• Record Type: Journal Article
• Authors: Xu, Yanghui; Ou, Qin; He, Qiang; Wu, Zhengsong; Ma, Jun; Huangfu, Xiaoliu
• Is Part Of: Journal of environmental chemical engineering. Volume 10:Issue 5(2022)
• Publication Date: 2022-10
• Subjects: Silver nanoparticles -- Activated sludge -- Adsorption -- Extracellular polymeric substances; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2022.108316
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: The extracellular polymeric substances (EPS) from activated sludge played significant roles in the removal of nanoparticles from wastewater. A series of batch experiments were carried out to determine the adsorption mechanism of three nano-Ag by activated sludge, as well as the contributions of EPS fractions including dissolved EPS (DEPS), loosely bound EPS (LB-EPS) and tightly bound EPS (TB-EPS). The results demonstrated that the adsorption of nano-Ag by sludge biomass agreed with pseudo-second-order kinetic reaction model and Freundlich isotherm model. About 26.0–41.2% of nano-Ag was trapped by the bound EPS (BEPS) matrix of activated sludge (especially LB-EPS) and 42.5–52.6% of them was adsorbed onto the inner cells after the adsorption. Moreover, the interaction energy contributions of EPS fractions followed the order of EDE > 0 > ETB > ELB, suggesting DEPS in wastewater went against the removal of nano-Ag due to steric repulsion while LB-EPS and TB-EPS were positive to nano-Ag adsorption by modifying biomass surface and providing extensive binding sites. Besides, EPS fractions played significant roles in the adsorption of nano-Ag with low initial concentrations but had limited effect at high concentrations. Overall, this study investigated the effect of EPS fractions on the adsorption behaviors of nano-Ag by activated sludge biomass, which is meaningful to understand the removal mechanism of nanoparticles in sewage and the potential role of EPS fractions. Graphical Abstract: ga1 Highlights: The adsorption process fit pseudo-second order kinetic and Freundlich isotherm model. BEPS and inner cells captured 26.0–41.2% and 42.5–52.6% of nano-Ag respectively. The contribution of DEPS was negative while that of LB- and TB-EPS was positive. The removal effect of EPS fractions on high concentration nano-Ag was limited.