We examined Karl Fischer titration as a method for accurately quantifying the moisture content of salt. To date, there has been no method for accurately quantifying the moisture content of salt, so the loss on drying and the loss on heating methods have been used to provide an indicative value. In spite of Karl Fischer titration being a useful method for quantifying moisture content, it has not been possible to apply it to salts. Specifically, Karl Fischer titration relies on the extraction of moisture, but salt does not dissolve in this reagent and sufficient moisture can not be extracted. Against this background, we attempted to dissolve salt in the Karl Fischer reagent. We found that the salt could dissolve in ethylene glycol. Therefore, for titration we used a mixed solution obtained by adding 40 mL of ethylene glycol to 100 mL of the Karl Fischer reagent. Using this method, the moisture content of a standard reagent could be accurately quantified. Two types of samples were used for the Karl Fisher titration flask. Using this method, the moisture content of salt can be quantified accurately.

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The partitioning at the active layer/aqueous interface is one of the key phenomena of the solute transport process across reverse osmosis/nanofiltration（RO/NF）membranes. The objective of this study was to develop methodologies to determine solute partition coefficients using Rutherford Backscattering Spectrometry（RBS）. This objective was accomplished by depositing a thin film of polyester material on top of the active layer and equilibrating these layers with an aqueous solution of the target contaminant. The distribution ratio of target contaminants between the polyester - polyamide active layer（K_PA-PE）was determined using RBS. The distribution coefficient of contaminants between water - polyester（K_PE-w）was independently determined using the conventional bottle-point technique. Then, K_PA-PE and K_PE-w were used to calculate the contaminant partition coefficients between the water - polyamide phases（K_PA-w）. The results showed that the partition coefficient of arsenious acid, dimethylarsinic acid, and iohexol into polyamide ESNA1-LF NF membrane are greater than unity, thus demonstrating that chemical interactions between solutes and membrane materials play a role in solute partitioning into RO/NF membranes. Also, the partition coefficient of ionized species（H₂AsO₃^－）was significantly lower than that of the conjugate neutral molecule.

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An iminodiacetate-type chelating fiber（IDA fiber）was prepared by means of radiation-induced graft polymerization of an epoxy-group-containing monomer, glycidyl methacrylate, onto a commercially available 6-nylon fiber and subsequent conversion of the epoxy group into an iminodiacetate group capable of removing radioactive strontium ions from seawater. Adsorption isotherms of the IDA fiber for three kinds of alkaline earth-metal group ions, i.e., Sr^2＋, Ca^2＋, and Mg^2＋, in artificial seawater were found to be well described by ternary-component Langmuir adsorption isotherms. We proposed a strontium removal technique for the immersion of the fiber with a divided amount rather than an undivided amount into seawater in a closed area. The reduction in the amount of fiber required for an identical removal percentage of strontium was demonstrated in a batch mode. Experimental adsorption-equilibrium data as a function of the number of divided immersions agreed well with the curves calculated from the ternary-component Langmuir adsorption isotherms and mass-balance equations for each alkaline earth-metal ion.

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The fouling behavior of Neosepta AMX and ASM was investigated in batch and flow electrodialysis systems, using humic acid（HA）and sodium dodecylbenzene-sulfonate（DBS）as foulants by measuring the voltage drop between probe electrodes. DBS fouled AEMs; however, in the case of HA, the voltage drop of the batch system increased while that of the flow system did not change. This is because the increase in the voltage drop in the batch system was caused not by fouling of HA, but by the increase in the solution resistance. From these results, the fouling test using the flow system indicated clearly that HA does not significantly foul AMX and ASM.

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A large reverse electrodialysis（RED）power generation system based on a commercial electrodialysis stack was built. The system has 200 pairs of cation- and anion-exchange membranes whose effective membrane area was 1000 cm². The performance test of the RED system was performed with model seawater（0.5 M NaCl）and model fresh water（various concentrations of NaCl）. The power density and gross power output of the system had a maximum value of 0.45 W/m² and 17.8 W, respectively, using 0.02 M and 0.5 M NaCl solutions. The calculated pumping energy was 2.76 W; hence, the net power of the system was 15.1 W.

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We fabricated osmotic agents（OAs）with controlled lower critical solution temperature（LCST）for the PRO system utilizing low-grade heat. In this experiment, several kinds of copolymers were synthesized as OAs from hydrophilic and hydrophobic tertiary amine monomers. The LCSTs of the copolymer solutions were controlled from 23.5 to 41.0 ℃ by changing the copolymer composition. The osmotic pressures of the obtained OA solutions dramatically increased in the presence of CO₂. The optimum copolymer composition of OA was suggested by the standpoints of LCSTs, high osmotic pressure and easy release of CO₂.

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