Adsorptive And Catalytic Functional Membranes And Water Purification

In order to protect the environment and human health, RO, NF or AOPs were used to remove micropollution to improve water quality. However, membrane fouling, oxidation by-products and their toxic side effect influence their application to some degree. The purpose of this paper is to develop a new cost-effective method to remove and mineralize trace organic pollutants containing multi-walled carbon nanotubes (MWNTs) and activated carbon fiber(ACF) and nano-sized TiO₂ particles, a combination of adsorbent and photo-catalyst functional membrane by using a sol-gel and dip coating method on Polyester (PET) membrane. Adsorption and then oxidation the micropollution on the seprated membrane. As the pollutants were mineralized, the oganic pollution of membrane effluent can be put an end.The prepared composite membranes and nano-TiO₂ particles were characterized by SEM, XRD,UV-Vis, FT-IR, et al.MWNTs were added to the sol gel solution derived from hydrolysis of Ti(OC₄H₉)₄ and doped with Ce³⁺, which was used to dip-coating polyester filter membrane, thus formed composite membrane was used to adsorb micropollutant from water statically. After adsorption reaching an equilibrium,the membrane were removed, to membrane saturated with pollutant bisphenol A, either photocatalysis or UV/Fenton reaction was applied to oxidize and degrade the adsorbed pollutant, to avoid by-product pollution of the purified water. The best adsorptive removal of BPA by MWNTs/TiO₂ composite membrane(MWNTs =46.00(wt.%)) was 71.5%, also measured was the repeated use of the membrane in pollutant adsorption removal and adsorption capacity regeneration using advanced oxidation(photo-catalysis). Compared with the initial adsorption removal rate, the adsorption restoration rate nearly doubled using 1h UV/Fenton oxidation than 2h UV alone 33% to 57%.Also, a series of composite functional membrane containing ACF powder (<240 mesh) and Ce³⁺-TiO₂, a combination of adsorbent and photo-catalyst on PET filter cloth, was prepared by using a sol-gel and dip coating method(drying at the temprature of 105℃). Both the static adsorption experiment and dynamic adsorption experiment were carried out. The results showed the following: The BPA adsorption removal rate by composite membrane with 11.33 and 29.87wt.% ACF in ACF/TiO₂ was 93% and 100%; The dynamic adsorption experiment showed that as high as 60% BPA removal was achieved in dynamic filtration /adsorption test, which removed 98.7% Koalinite solid suspends at the same time. Also measured was the repeated use in BPA removal and adsorption capacity regeneration using advanced oxidation(photo-catalysis). Compared with the initial adsorption removal rate, the adsorption restoration rate were 72% after 2h UV and Fenton reagents' oxidation for the second time adsorption. The adsorption process followed a first order kinetics. Introducing TEOS in the preparation of sol gel solution and subsequent coating to form composite membrane, improved membrane adsorption stability after regeneration treatment by UV-Fenton. 90% highest adsorption retoration was reached for SiO₂/TiO₂/ACF membrane.