Polytitanium sulfate rich with dominant-flocculated-species prepared by electrodialysis towards ceramic membrane fouling control

Abstract

Ceramic membrane has always been of concern due to its high flux, fouling-resistance, and chemical-resistance. Membrane fouling is always an ever-lasting problem, and pre-coagulation is a high-recognized very effective and common methodology for membrane fouling control. Herein, a kind of high-efficient polytitanium sulfate (E-PTS) rich with dominant-flocculated-species was firstly developed by electrodialysis towards membrane fouling control. Electrodialysis well controlled the rate of polymerization among Ti-species and hydroxyl by regulating directed migration of electron through micro-interface. Both Ti-ferron and electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) demonstrated the production of Tib and Tic as dominant-flocculated-Ti-species, accounting for 41.36 % and 42.18 %, respectively. The E-PTS had strong coagulation capability for the removal of biopolymer (BP), humic substance (HS), low molecular weight acid (LMWA), and low molecular weight neutral (LMWN) as proved by SEC-OCD-OND test. This was the very reason for the ca. 20 % higher removal efficiency of E-PTS coagulation over conventional polyaluminum chloride (PAC) and polyferric sulfate (PFS). Strong capability of coagulation with E-PTS enabled the follow-up filtration with ceramic membrane yielded large flux up to 361.0 LMH. More notable was that, continuous operation of membrane filtration for 30 h saw a stable high flux with no membrane fouling. The E-PTS pre-coagulation coupled with ceramic membrane filtration, a compact flow route, could realize both high-efficient water purification and membrane fouling control.