Comparison Analysis On Characterization Of Polyamide Composite Reverse Osmosis Membrane

During the past decade a variety of "new generation" water treatment membranes have been developed. These polymeric films may generally be divided into two categories. The first consists of dense polymers with high salt rejection for reverse osmosis (RO) processing of seawater and brackish water. The second category of films is appropriate for nanofiltration (NF) and ultrafiltration (UF) systems. In both categories, the membranes have been vastly improved. Despite these improvements, a decline in membrane performance over time results from membrane fouling. Since the interaction of organic and inorganic colloidal substances with membrane surfaces in aqueous media is dependent on the charge of the membrane surface, determination of the zeta potential of the membrane surface is critical to membrane fouling research.In this thesis, the zeta potential is introduced in theory firstly, and the application of zeta potential on the membranes both at home and abroad is too. At home, the research upon zeta potential is focused on nanofiltration (NF) and ultrafiltration (UF) systems, and the field of reverse osmosis (RO) is blank. The technology of reverse osmosis is weaker than it is abroad. But we can see that the research of zeta potential in theory and the technology of analysis on it are both improved, the improvements of which can be transplanted into the reverse osmosis (RO), and the improvements have established a few steady basis. The technologies on the analysis of zeta potential abroad have been very mature, and the applications of reverse osmosis have been got more and deeper successes.The formation and causes of surface potential are expounded in detail in this paper, addition to it, some approaches to measure it are enumerated. An electrochemical method to measure the surface potential on membranes is introduced in this paper. In results, we can understand that the property of the solutions which affects the surface potential on the membranes strongly. The different properties, concentrations and pH all can affect the surface potential on membranes seriously. The electrochemical method can measure the surface potential on membranes under some conditions, and afford some relative data for the applications and researches of membranes in various fields, which can direct some ways for the improvements of membranes' performance levels.To know the discriminations of our company's products comparing to the products of other overseas companies, we do the analysis of scanning electron microscope to theproducts of our company and that of Dow chemical (USA). As a result, in the whole technical processing of production, the varieties are due to the varieties of the layer of polysulfone about the sectional structure, the entire trends of which are from close to loose. The sectional structure of the membranes produced by our company are like sponge, like as that by Dow chemical, but our products are looser than Dow chemical's obviously. Seen from the surface of the membranes, the layer of PA is spinal. The finally products of our company are different from which of Dow chemical, through some characters of them are similar, such as the shape of the PA , and all of these differences are due to the varieties of the protective layers. See to the tests upon the compaction properties of the membranes, the processing about pressing the membranes to close chiefly occurs on the loose layers of the polysulfone. The results of the flush tests prove that our products' protective layers are washed away mostly as which of the Dow chemical.