Papers by Keyword: Anti Fouling

Abstract: Membrane surface modification is the important method to decrease membrane fouling. Recent efforts have been made to develop the hydrophilic modified ceramic membrane with nano-sized inorganic coating in our research group. In the modified membrane, the nano coating does not form a separating layer, just distributes uniformly on the surface of the membrane pore wall. It results in that: (1) if the feed is water, the water flux of the modified membrane is higher than that of the unmodified one despite the fact that the mean membrane pore size decreases after the modification; (2) if the feed is oily emulsion, the steady flux is obtained in a short time and keeps in the following time. The flux is far higher than that of the unmodified one because the hydrophilic nano coating prevents the cake from forming on the membrane surface. The nano-sized metal oxide modification application in the membrane technology not only expands the newly research area of the membrane technology but also makes the modified ceramic membrane have a good perspective application in the industry. This paper will introduce the development of the modified membrane with nano inorganic coating and give a clear future research direction.

Abstract: Biofouling prevention remains a major challenge to the chemists, and researchers around the world who are engaged in the development of antifouling paints that can prevent growth of organisms like barnacles, algae and tubeworms on the submerged structures. Growth of organisms on the surfaces exposed to marine and freshwater environment not only reduces the efficiency of such structures, e.g. reduction of heat transfer etc, but also causes structural damages. In order to prevent the growth of organisms on surfaces of the marine and freshwater environments, coatings containing biocides are generally used. However, use of biocides not only leads to the corrosion of the metallic structures in some cases, but it also inflicts severe damage to the aquatic ecosystem. It is thus necessary to develop anti-biofouling paints that are innocuous to both the environment and the structures. One alternative approach may be incorporation of nanoparticles, and preventing bacterial bio-film formation as well as the attachment of larger organisms. Various nanoparticles of metal and their oxides have been recognized to possess antibacterial properties. The development of such materials is a challenge to both the chemist and the biologist, where effective choice of methods that provide relevant information regarding application of the metal nanoparticles in anti-fouling materials, becomes the central objective. The present article is a short review in the area of nanoparticle doped antifouling paints. In addition, some aspects covering our experimental results on the selected bio-fouling paints with dispersed nanoparticles of ZnO, CuO, Al2O3, MgO, TiO2 and Co3O4. It also discusses the techniques used for the characterization of the nanoparticle-doped materials and methods for the determination of their efficacy against bio-film formation.

Abstract: In this paper, the in-situ exposure tests of 15 kinds of copper and its alloys were carried out in seawater at Zhanjiang Harbor for 12 months in order to study their anti-fouling abilities and anti-corrosion properties. In the same way, the in-situ anti-fouling tests of copper and bronze were performed in Qingdao for 8 years. Successively, the anti-fouling properties were analyzed combining with the electrochemical process of copper alloy corrosion and biology process of the adhesion. The chemical, physical and biological factors influencing the fouling properties of copper alloys were also investigated. The results showed that the coppers can equip themselves with antifouling performance by producing some toxic substances during the processes of chemical and electrochemical reaction. In addition, the antifouling ability was proved to relate to the exfoliation effect, which was the result of interaction between stain layer adhesion and spalling force of the attachments.

Abstract: As concerning the high toxicity of organotin paints, the need to develop new environment-friendly antifouling agents has been highlighted. The paper mainly focused on the synthesis of siloxane-acrylic resin and its antifouling performance. The antifouling properties of resins were carried through by the colonization of benthic diatoms (Nitzschia flosterium) and ocean plates of offshore platform. The paper also disclosed that the silicone oil (5.5%, w/w) introduced to siloxane-acrylic resin was significant positive effect for enhancing the antifouling performance in Qingdao ocean.

Abstract: Tourmaline has unique electrical properties originated from its crystal structure such as pyroelectricity, piezioelectricity and emission of anion. These properties can derivate the making of feeble current around 0.06 mA. This weak current enables to electrolyze continuously and to make the hydroxyl anion, which may play a role of surface active agent against fouling of ocean organism. Two kinds of the mixture, tourmaline-monazite-quartz and tourmaline-monazite-illite-zeolite, were tested for the filling materials of antifouling paints. As a whole, the anion emits actively, at least around 4000 negative ion/cc. This high emission property maintains constantly for long time over 500 days. This implies that the tourmaline mixture treated mechanochemically can emit anion over 4000 negative ion/cc for a long time. These results enable us to make possible for application of the tourmaline containing mixture as the filling materials of antifouling paint

Abstract: In this paper results of electrophoretically activated processes for domestic wastewater treatment in lab and field scale experiments are presented. The principal mechanisms of non-membrane and membrane based electrokinetic solid liquid separation by electrophoresis are described. In the case of non-membrane based electrokinetic wastewater treatment a modular processing scheme is suggested in order to achieve economically and ecologically suitable processing conditions based on colloidal wastewater characteristics. In the case of membrane based electrokinetic waste water treatment an effective anti-membrane fouling process is designed controlled by colloidal characteristics of the wastewater, especially zetapotential, as well as external field parameters and microfiltration module geometries. The specific energy input of the membrane based and non-membrane based electrophoretic waste water treatment methodologies are compared and future perspectives of electrokinetic activated waste water purification processes are proposed.