NER: Separtation of Nano-Sized Aquatic Particles by Electrically Assisted Tangential Flow Filtration: System Evaluation and Metal Speciation

University Of Delaware, Newark DE

Investigators

Abstract

0209246 Huang This proposal was received in response to the Nanoscale Science and Engineering Initiative NSF 01-157, category NER. Aquatic particulates, regardless of their chemical composition, have two very important properties that are closely related to water quality: particle size and surface charge. Chemical species, e.g., metal ions, are readily accumulated at the solid-water interface, which can affect the assessment (or determination) of "soluble" concentrations of chemical species in waters. Currently, the "insoluble" and "soluble" chemical species are determined by filtering water samples through 0.45-um filters; things that pass through the filter are "soluble" and things that are retained by the filter are considered insoluble". Accurate assessment of "soluble" or total chemical concentrations in waters requires an effective solid-water separation technique. As water quality standard becomes increasingly stringent, demand for effective separation of nano-sized particles from waters or wastewaters will increase. This will over-burden the current filtration practice of filtration with 0.45-um filters and render it ineffective. The proposed research project will test two hypotheses: (1) Electrically assisted tangential flow (EATF) filter can perform independently of membrane selection; (2) The distribution of metal ions in natural waters is affected not only by the particle size but also by the surface charge condition of naturally occurring particulates. The following specific objectives are to be achieved with carefully designed laboratory experiments: (1) design and evaluation of the performance of an electrically assisted tangential flow filtration system; (2) separation of selected nano-sized aquatic particulates both naturally occurring particles and pathogenic microorganisms, exemplified by Cryptosporidium, by EATF filtration, and (3) elucidation of the effect of surface charge and particle size of naturally occurring particulates on the distribution and speciation of selected meal ions. Success of this project will (1) contribute to theoretical development of EATF filtration process, (2) lead to the development of an innovative process for the separation of aquatic particles according to their size and surface charge conditions, (3) gain insight into the effect of particle size and surface charge conditions on the speciation of metals in natural waters, and (4) train two doctoral students with a multi-disciplinary program. The proposed research has the potential to eliminate or minimize membrane-fouling, promote reuse of electronic chip processing wastewater, and enable nano-scaled metal speciation.