Optical microscopy study of the sorption surface of nanofiltration membranes OPMN-P and OFAM-K

Abstract

Literature review of research data of surface morphology of porous semipermeable membranes is presented in this article. The main goal of this work is optical and microscopy research of microstructural heterogeneities of nanofiltration membranes surface. Types of researched membranes (OFAM-K and OPMN-P) are choosen and this choice is based on literature review and main goal of research. Also main parameters (pressure, minimal productivity, selectivity, work range of pH, maximal temperature) of this membranes are presented in this paper. Besides it, the method of optical microscopy research of microstructural heterogeneities of membranes surface, which were choosed, is reviewed. This method includes several stages: optical research with fixating of images, data export to AutoCAD 16 and choice of three square zones with size 10000 μm² , description of dark microstructural heteroheneities on the active layer of membranes by diameter sizes, data extract by using standard AutoCad 2016 functions and the implementation of a three-table sample, calculation of the square of dark and clear surfaces, contamination coefficient, analysis of received data by using Microsoft Excel 2010, histograms creating (scope determination, splitting the received range of the sample to several intervals, determination of the interval width), the definition of key parameters (in data analysis) Excel (average diameter, microstructural heterogeneities, the standard error calculation, standard deviation and skewness), creating of the function of normal diameters distribution of the microstructural heterogeneities of the membranes. In addition, a discussion of the results about the characterization of the main parameters of microstructural inhomogeneity of the membranes, based on the processing of the experiment, methods of mathematical statistics and literature data, has been carried out in this work. The regularity has been revealed, that sample membrane OFAM-K has a smoother texture compared to the more relief texture of OPMN-P, that probably affects the fouling of the membrane surface. In conclusion it is possible to say that the method of optical microscopy in conjunction with the using of AutoCAD 2016 and Microsoft Excel 2010 allows to explore with good accuracy the microstructural heterogeneity of the original samples of nanofiltration membranes OFAM-K and OPMN-P.