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Using Fractionated Natural Organic Matter to Study Ozonation By-Product Formation
Published in A. Minear Roger, L. Amy Gary, Disinfection By-Products in Water Treatment, 2017
The materials isolated locally were characterized by ultraviolet (UV) absorption (254 and 270 nm) and elemental analyses. FT-IR spectra were obtained from cast films of the isolated material. Average molecular weights were determined by vapor pressure osmometry. 13C NMR analyses were performed on selected samples. Similar data characterizing the Suwannee River fulvic acids were obtained from the IHSS where available, or from Aiken et al.44
Measurement of Molecular Weight and Its Distribution
Published in Anil Kumar, Rakesh K. Gupta, Fundamentals of Polymer Engineering, 2018
where PA is the vapor pressure of the pure solvent at temperature T. This lowering in vapor pressure is utilized for the measurement of molecular weight in the technique known as vapor-pressure osmometry.
Dimerization of 2-Ethylhexylphosphonic Acid Mono-2-ethylhexyl Ester (HEH[EHP]) as Determined by NMR Spectrometry
Published in Solvent Extraction and Ion Exchange, 2021
Ashleigh Kimberlin, Kenneth L. Nash
Much of the challenge impacting more detailed characterization of these systems arises from the complexity of solvent extraction phenomena. After the extraction reaction is completed, the organic phase can be considered to contain the diluent, monomerized extractant, aggregated extractant, the extracted metal complex(es), any aggregations of the metal complex, extracted acid, and some amount of water. Most of these components must be neglected in order to simplify the system sufficiently for analysis. In most cases, this is not an issue, as some species only become relevant under extreme conditions (i.e. coordination polymers).[11] However, for more common species, this can cause differences in apparent solution behavior depending on how the data set is collected. For example, most of the dimerization constants reported for organophosphorus extractants have been collected either via acid/base titration in ethanol/water mixtures or through the partitioning of the extractant across the interface.[12] Both methods probe the pKa and the dimerization constant simultaneously, which can lead to the two constants being coupled in the analysis. IR spectroscopy can be used to probe organic-phase interactions; however, due to the limit of detection, high concentrations of the ligand are needed, limiting the scope of any investigations utilizing this technique. Vapor pressure osmometry has also been used for this purpose but is limited to use in very volatile solvents and it has the same concentration issue as IR spectroscopy.[13,14]