Mr Junmeng Li - Student Seminar Presentation - June 26 2015

C5MPT Student Seminars

Mr. Junmeng Li

University of Alberta,

Chemical and Materials Engineering

June 26, 2015 | ETLC E2-001

1:00 PM

 

Lecture

ABSTRACT

 

 

Understanding the mechanism of interactions between elemental selenium and coagulant/flocculant in wastewater

 

Industrial approach of selenium management includes Fluidized Bed Bioreactor (FBR) technique, which reduces selenium oxyanions to generate elemental selenium with low solubility and bioavailability.  Coagulants and flocculants have been used to facilitate the precipitation of elemental selenium (SE0) particles.  In this work, precipitation and settling of selenium nanoparticles in wastewater were investigated with amorphous ferric oxyhydroxide(Fe(OH)3) as coagulant prepared from FeCl3 and polyacrylamide (PAM) as flocculant.  The effect of conditions (i.e., pH value and salinity) on the settling efficiency, and interactions of selenium nanoparticles, ferric oxyhydroxide, and PAM were investigated by Inductively Coupled Plasma (ICP), and settling experiments.  Our results suggested an optimal settling condition of pH 9.  The results from Quartz Crystal Microbalance with Dissipation (QCM-D), zeta potential, and Atomic Force Microscopy (AFM) indicate that the attachment of elemental selenium to ferric oxyhydroxide was governed by Derjaguin-Landau-Verwey-Overbeek (DLVO) forces.  The attachment was enhanced in high salinity due to the compression of electrostatic double layer, and the detachment was restrained because of the presence of polymer-like ferric oxyhydroxide.  PAM intertacted with ferric oxyhydroxide through polymer bridging, which in turn facilitated the settling and precipitation of selenium nanoparticles.