Development of bench and full-scale temperature and pH responsive functionalized PVDF membranes with tunable properties

Abstract

Temperature and pH responsive polymers (poly(N-isopropylacrylamide) (PNIPAAm), and polyacrylic acid, PAA) were synthesized in one common macrofiltration PVDF membrane platform by pore-filling method. The microstructure and morphology of the PNIPAAm-PVDF, and PNIPAAm-FPAA-PVDF membranes were studied by attenuated total reflectance Fourier transform infrared (ATR-FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The membrane pore size was controlled by the swelling and shrinking of the PNIPAAm at the temperature around lower critical solution temperature (LCST). The composite membrane demonstrated a rapid and reversible swelling and deswelling change within a small temperature range. The controllable flux makes it possible to utilize this temperature responsive membrane as a valve to regulate filtration properties by temperature change. Dextran solution (Mw=2,000,000g/mol, 26 nm diameter) was used to evaluate the separation performance of the temperature responsive membranes. The ranges of dextran rejection are from 4% to 95% depending on the temperature, monomer amount and pressure. The full-scale membrane was also developed to confirm the feasibility of our bench-scale experimental results. The full-scale membrane also exhibited both temperature and pH responsivity. This system was also used for controlled nanoparticles synthesis and for dechlorination reaction.

Stimuli responsive and low fouling ultrafiltration membranes from blends of polyvinylidene fluoride and designed library of amphiphilic poly(methyl methacrylate) containing copolymers

“…As a result, fluxes of the membranes decrease. The temperature responsive behaviour of PNIPAM was described elsewhere [18,21,22,37]. It is seen that the effect of temperature is more pronounced in PVDF-C1 (117% flux enhancement from temperature 25 1C to 35 1C, plot c) than that of AC1 (30% flux enhancement plot a 0 ) and BC1 (ca.…”

“…On the other hand, PVDF-B1 (plot b) and PVDF-BC1 (plot b 0 ) exhibited positive effect on permeate flux (flux enhancement 62-65%) when feed pH was lowered from 7 to 5. At lower pH, the PMMA-co-PAA and PMMA-co-PAA-co-PNIPAM in the PVDF-B1 and PVDF-BC1 undergo compaction due to de-ionization of AA units [18,21]. Thus at lower pH the pore opening takes place in the membranes containing PAA as one of the polymer component.…”

Layer-by-Layer-Assembled Laccase Enzyme on Stimuli-Responsive Membranes for Chloro-Organics Degradation

“…1–2 Recently-developed functionalized membranes with porous support and functional polymer matrices provide the possibility of tuning the membrane pore structure, selectivity, and reactivity. 3–5 Moreover incorporation of stimulus-responsive materials into the pores expands the applicability of the membranes into areas such as separation, biosensors, delivery systems etc. 6–8 Introduction of functional polymers into the membrane pores enables deliberate immobilization of biological molecules such as enzymes within the polymer matrix, thus allowing catalytic remediation of toxic organics in water.…”

Engineered iron/iron oxide functionalized membranes for selenium and other toxic metal removal from power plant scrubber water

“…We recently reported the development of full-scale polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) membrane with iron/iron oxide nanoparticles for combined reductive and oxidative degradation of polychlorinated biphenyls (PCBs) in groundwater [23–24]. The same redox chemistry and membrane approach can be used for selenium removal from coal-fired power plant scrubber water, as iron has been reported to reduce selenate (VI) and selenite (IV) to elemental selenium (Se 0 ) and selenide (-II) [25–27].…”