Electrosorptive removal of organic water constituents by positively charged electrically conductive UF membranes

Publikationstyp
Journal Article
Date Issued
2021-08-01
Sprache
English
Author(s)
Mantel, Tomi Jonathan  orcid-logo
Jacki, Elena  
Ernst, Mathias  orcid-logo
Institut
Wasserressourcen und Wasserversorgung B-11  
TORE-URI
http://hdl.handle.net/11420/9690
Journal
Water research  
Article Number
117318
Citation
Water Research 201: 117318 (2021-08-01)
Publisher DOI
10.1016/j.watres.2021.117318
Scopus ID
2-s2.0-85107815415
Publisher
Elsevier Science
Negatively charged electrically conductive ultrafiltration (UF) membranes have been intensively investigated for fouling mitigation and rejection enhancement in recent years. This study reports the novel approach of applying positive charge (+2.5 V cell potential) to a conductive membrane to induce electrosorption of negatively charged substances onto the membrane. Subsequently, desorption of negatively charged substances is achieved by changing the potential periodically (e.g., after 30 min) to negative charge (-2.5 V cell potential). For this purpose, sputter deposition of ultra-thin gold layers (40 nm) is used to generate electrically conductive gold-polymer-gold flat sheet membranes by coating the active and the support layer of two commercial polymer UF membranes (polyethersulfone UP150, polyamide M5). When M5 membrane was charged positively during filtration (+2.5 V), Suwannee River NOM, Hohloh lake NOM, humic acid and Brilliant Blue ionic dye showed removal rates of 70 %, 75% and 93% and 99%, respectively. Whereas, when no potential was applied (0 V) removal rates were only 1 – 5 %. When a positive potential was applied to the active membrane layer and a negative potential was applied to the support layer (cell potential 2.5 V), a significant increase of flux with 25 L/(m² h) was observed due to the induction of electro-osmosis. Electrosorption was only observed for M5 membrane (ζ: +13 mV, pH 7) and not with UP150 membrane (ζ: -29 mV, pH 7). Due to a low current density of 1.1 A/m² at a flux of 100 L/(m² h), the additional energy consumption of electrosorption and desorption process was low with 0.03 kWh per m³ of permeate. This study delivered the proof of concept for the novel process of electrosorptive UF with energy consumption between microfiltration and ultrafiltration but NOM removal rates of nanofiltration membranes.
Subjects
Electrically conductive membrane
Electrosorption
NOM
DDC Class
500: Naturwissenschaften
530: Physik
540: Chemie
600: Technik
620: Ingenieurwissenschaften