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

Lina Chi,Zhenjia Zhang,Yingjia Qian,Zheng Jiang,Boyu Zhang

doi:10.1007/s13203-016-0158-x

Lina Chi, Zhenjia Zhang + Show 3 more

Open Access

https://doi.org/10.1007/s13203-016-0158-x

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Abstract

Immobilization of nano-scaled TiO2 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 self-cleaning performance of the novel TiO2/PAA/PTFE UF membranes, which were coated via an innovative plasma-intensified coating strategy. Through careful characterizations, the enhanced engineering properties and the self-cleaning 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 TiO2/PAA/PTFE composite membranes could be recovered with simple hydraulic cleaning combined with UV irradiation. The mechanical properties and thermal stability of TiO2/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 TiO2 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.

Highlights

Polytetrafluoroethylene (PTFE) is featured with relatively high thermal stability, excellent chemical inertness, low surface tension, and small coefficient of friction, which endow PTFE with an excellent performance in diverse applications including low friction films, seals, electronic and biomedical devices
The mechanical properties and thermal stability of TiO2/polyacrylic acid (PAA)/ PTFE satisfy the practical application in water and wastewater treatments, despite that the original engineering properties were slightly influenced by PAA grafting and TiO2 coating
The surface roughness, mechanical strength, and selfcleaning capability of the TiO2/PAA/PTFE composite membrane fabricated with plasma-intensified coating process, were carefully investigated to evaluate its potential for practical wastewater ultrafiltration

Summary

Introduction

Polytetrafluoroethylene (PTFE) is featured with relatively high thermal stability, excellent chemical inertness, low surface tension, and small coefficient of friction, which endow PTFE with an excellent performance in diverse applications including low friction films, seals, electronic and biomedical devices. Porous PTFE membranes have found special importance in water treatment [1], separators of lithium-ion batteries [1, 2], pervaporation [3], and blood purification [4]. The presence of strong C–F bonding and water repellence makes the application of PTFE membranes in water treatment field less competitive because of the rather low water flux. Membranes are modified via five principal methods: (1) photo-initiated grafting and miscellaneous grafting; (2) plasma treatment; (3) physical coating/adsorption; (4) chemical reaction modification; (5) surface modification of membranes via nanoparticles impregnation [5]. The current trend is to coat or incorporate nano metal dioxide particles with the bulk membrane materials to enhance the performance of the membranes, such as hydrophilicity, permeate flux, photocatalytic activity, antifouling, water purification, and pollutant removal [6].

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