Three chelating resins (RNHs) based upon the low-crosslinked poly (acrylonitrile-co-divinylbenzene) have been prepared by the reaction with hydroxylamine in methano I at 80°Cfor 2 h. The base copolymers (RNs) were synthesized by a suspension polymerization using divinylbenzene (DVB, 5mol%) as a crosslinkingreagent and benzoyl peroxide (BPO, 40 and 180 mmol dm-3 monomer) or azobisisobutyronitrile (AIBN, 180 mmol dm-3 monomer) as a polymerizatioll initiator in the presence of toluene (100 vol%) as a diluent. Despite having superficially similar physical pore structures and chemical properties, thechelating resins derived from the low-crosslinked acrylonitrile-divinylbenzene copolymer beads whichwere synthesized using AIBN (180mmol dm-3 monomer) showed remarkably enhanced adsorption ratefor ufanium from seawater. The adsorption abilities of RNHs for uranium were examined as a hmctionof pore structure in swollen state. As expected from the literature, the diffusion of uranium was remarkably hastened.by the alkaline treatmentthrough micropore formation and chemical structura I changes as well. Here, it is important tonote that tbe mechanical strength of these nomina11y 5% crosslinked chelating resins was good enoughfor handling even after the treatment with a solution of NaOH (1 mol dm-3) at 30°C for 72 h. Asuperior adsorption rate as high as 130 mg of u/dm-3-resin/10 days (650mg of U/kg-resin/10 days) was achieved in a large-scale columnar adsorption test (resin 50cm-3, SV 650 h-1, seawater temperature 25-28°C).
Four kinds of spinel-type manganese oxides were prepared by the acid treatment of lithiummanganates which were obtained with different methods and conditions. Their bulk and surfaceproperties were investigated by chemical, X-ray, DTA-TG analyses, and nitrogen adsorption-desorptionat-196°C. Although their X-ray diffraction patterns resembled each other, the DTA-TGcurves and surface characteristics varied widely depending on the preparation conditions. The adsorptive properties of the manganese oxide adsorbents for lithium ions were investigatedin the brine of Daquidham salt lakes and in NH4Cl-NH3(aq) buffer solutions containing LiCl. Lithium uptake from the brine varied between 1.4 and 25.9 mg/g depending on the preparationconditions. The lithium uptake by the adsorbent was well correlated with its weight loss between 100 and 300°C in the TG curve. This correlation suggests that the lithium ion adsorption takesplace not on the redox-type sites but on the Li-specific ion-exchange sites of the spinel-type manganese oxide.
The effects of the number of nozzles on the change of nonequilibrium temperature differencewere investigated for the spray flash desalination plant. Superheated water at about 30°C is injectedinto a low pressure chamber through cylindrical nozzles. This temperature is nearly equal tothe temperature of the surface seawater, and lower than that of conventional desalination plant. The number of nozzles was changed from 2 to 6 and the range of the flow rate was from 0.5to 4.0 t/h. The reduction of the nonequilibrium temperature difference (NETD) and phenomenaof the spray flash evaporation are shown. In the case where the flow rate is high, NETD is affectedby the number of nozzles. On the other hand, when the flow rate is low, the effect of the number of nozzles is not observed.
A salt-making facility A in the U.S.A. produces common salt (>99.85%) and pure salt (estimated>99.99%), which are made from brine obtained by solution mining from a bed of rock salt. Onthe other hand, salt is produced by eight facilities in Japan. Seven of them use the brine concentrated sea water by ion-exchange membrane electrodialysis method and one uses the brine dissolved solar salt. In this paper, we made the flow sheet of the salt-making process of facility A based on someoperating data, and attemped to clear some differences of producing techniques, compositions ofthe brine and the bittern and efficiencies of production among facility A, domestic reproductivefacility (facility B) and four dometic facilities with quardruple-effects system. The results wereas follows. 1) The method of using the waste heat is different between facility A and domestic facilities. 2) The apparatuses for dehydrating and drying products are different. 3) The operation of crystallization process is controlled under the standard according to the composition of brine, because it changes by the method of producing the brine and the grade ofpurifying it. 4) Facility A produces common salt on low concentration of impurities in the mother liquid. On the other hand, facility B produces the same grade salt as refined salt with purification ofbrine. 5) In the comparison of the energy cost of crystallization, from least to most expensive in orderwere facility B, facility A and then the domestic facilities of quadruple-effects system. Thisis greatly affected by the number of effects and the concentration of brine. 6) When the energy cost was calculated by taking the number of effects and the concentration ofthe brine into consideration, the result was different. From least to most expensive in orderwere the domestic facilities of quadruple-effects system, facility A and then facility B. How ever there was little difference in cost among the facilities.