Evaluation of the Quality Assurance of Ultrafiltration Separation for Humic Substances by Chemical Probes

摘要

The characterization of the molecular size of natural organic matter (NOM) is a valuable tool when assessing the effect of this material on the performance of water treatment systems as well as its geochemical origin (1). Size fractionation is usually accomplished by size exclusion chromatography (SEC) or Ultrafiltration (UF). The UF separation uses membranes with different cutoffs (e.g., 1,5 and 10 kDa). Unfortunately, membrane manufacturing generates a range of pore sizes and many membrane manufacturers use molecular weight cutoff (MWCO) metrics based on a 90% retention of given solute after specified duration of filtration (2). Present calibration studies are incomplete and differ by manufacturer: usually a single brand of membranes and a limited number of shaped and charged molecular probes are used (3-6). Thus, MWCOs are subjective and depend upon the shape and charge properties of the solutes used.