Surface engineering and self-cleaning properties of the novel TiO2/PAA/PTFE ultrafiltration membranes

Abstract

Immobilization of nano-scaled TiO 2 onto polymeric ultrafiltration (UF) membrane offers desirable antifouling and self-cleaning properties to the membrane, which is practical in wastewater purification only if the mechanical strength and long-term self-cleaning durability are realized. This paper reported the surface roughness, mechanical properties, thermal stability, and recycling selfcleaning performance of the novel TiO 2 /PAA/PTFE UF membranes, which were coated via an innovative plasmaintensified coating strategy. Through careful characterizations, the enhanced engineering properties and the selfcleaning performance were correlated with the surface chemical composition and the creative coating technique. In the recycling photocatalytic self-cleaning tests in photodegradation of methylene blue (MB) solution, about 90 % MB photocatalytic capability of TiO 2 /PAA/PTFE composite membranes could be recovered with simple hydraulic cleaning combined with UV irradiation. The mechanical properties and thermal stability of TiO 2 /PAA/ PTFE also satisfy the practical application in water and wastewater treatments, despite that the original engineering properties were slightly influenced by PAA grafting and TiO 2 coating. The changed properties of the composite UF membrane relative to PTFE are reasonably attributed to the variation of the surface chemical species and chemical bonding, as well as the thickness and evenness of the surface functional layers.

Efficient Photocatalytic Degradation of Organic Pollutant in Wastewater by Electrospun Functionally Modified Polyacrylonitrile Nanofibers Membrane Anchoring TiO2 Nanostructured

“…The highest surface roughness of PAN_Coa NFs membranes is attributed to the synergy of chemical treatment and random deposition of TiO 2 NPs on the membrane surface. Similar results indicating increased surface roughness of the membrane due to the chemical modification of the membrane and the random deposition of TiO 2 NPs on the membrane surface have been reported in the literature [ 46 , 47 ]. The increased surface roughness of the PAN_F and PAN_Co NFs membranes compared to the PAN_P NFs membrane could be explained by the chemical modification of the membrane ((PAN_F) as mentioned earlier) and the random dispersion of TiO 2 NPs in the polymer matrix(PAN_Co) [ 32 ].…”

Novel g-C3N4/TiO2/PAA/PTFE ultrafiltration membrane enabling enhanced antifouling and exceptional visible-light photocatalytic self-cleaning

“…Recently, we established a novel and effective 3-step successive manufacturing protocol for tightly binding TiO2 layer onto PTFE UFM [16,17] : First, the strong C-F and C-C bonds of PTFE surface were broken by active plasma to generate free radicals on the membrane surface, which immediately transformed to relatively stable peroxy radicals once exposed to air. In the following second step, as the plasma-treated PTFE immersed into acrylic acid (AA) solution, the peroxy radicals would initiate in-situ polymerization of AA to form ultra-thin yet strong bonded poly acrylic acid (PAA) film on PTFE.…”

“…Although the surface TiO2 functional layer can greatly improve the hydrophilicity and antifouling properties of the PTFE UFMs, their self-cleaning ability can only be realised under energy-intensive UV illumination owing to the large band gap energy (3.2 eV) of TiO2 [17,23] . Therefore, it is vital to coat visible-light-responsive TiO2 on to the PTFE UFMs for better use of the larger portion of the sunlight and thus further reducing operation costs in energy consumption and maintenance [24,25] .…”

“…A 3-step modification methodology was developed to modify the PTFE membranes, including the successive processes [17] . : plasma pre-treatment of PTFE, graft polymerization of AA onto pre-treated PTFE to form PAA/PTFE, and TiO2 self-assembly onto the PAA/PTFE to obtain the composite membranes.…”

Surface hydrophilizing modification of polytetrafluoroethylene/glass fiber fabric through oxidant-induced polydopamine deposition

“…Polytetrafluoroethylene (PTFE) is a kind of material with excellent chemical stability, thermal resistance, high mechanical strength, and erosion resistance [1]. Due to these characteristics, it has been extensively utilized in the field of water treatment [2], separators of lithium-ion batteries [3], pervaporation [4], and blood purification [5]. Glass fiber (GF) fabric has the advantages of high strength and good thermal stability.…”