This study was made to investigate about the effect of initial Li/Ca atomic ratio on improvement of afterglow time of Eu2+, Pr3+ codoped CaS. Eu2+, Pr3+ codoped CaS with Li (phosphor) was synthesized by reducing mixture of Li2CO3 and Eu3+, Pr3+ codoped CaSO4·2H2O. The lattice constant of the obtained phosphor expanded by incorporation of Li+ ion into CaS structure. This result was because Li+ ion invaded to the interstice of lattice. The phosphor emitted red by irradiation of black light and D65 lamp. The emission wavelength of phosphor was observed at 644 nm. In the case of initial Li/Ca atomic ratio of 0.04, the afterglow time of phosphor irradiated light of 486 nm was greatest 80 minutes. The afterglow time was prolonged to about 5 times by forming cation hole which could capture a lot of electron. The phosphor had the two kinds of cation hole formed by incorporation of Li+ ion and Pr3+ ion. The improvement in afterglow time was because depth of a trap of cation hole formed by addition of a Li+ ion was shallow. The depths of trap of cation hole formed by incorporation of Pr3+ ion and Li+ ion determined by the Hoogenstraaten method were 0.202 eV and 0.118 eV, respectively.
The present study was conducted on the chemical recycling by thermal degradation of recycled polyethylene terephthalate (PET) bottle by using calcium hydroxide that a species of hydration products of OPC. The mixture of PET and calcium hydroxide was depolymerized on salt bath under nitrogen at 300°C for from 15 io 180 minutes.The degradation at 300°C for 60 minutes gave 96.6% yield of terephthalic acid (TPA). When used inorganic materials, such as aluminum oxide, talc, aglmatlite, quartz and gypsum, except for calcium hydroxide, yield of TPA did not increase above 20%. From the results of thermal degradation of PET, it was proved that calcium hydroxide play an important role to depolymerization of PET bottle.
The Fe (III) compound, (2-) -o, o'-phosphonate iron (III) ethylphosphate, was prepared by the reaction of diethyl phosphonate with ferric nitrate in acetonitrile solvent at 100°C for 2 hour. The reaction of diethylphosphonate with ferric nitrate in water and acetonitrile solvent were studied, and the mechanism for the formation of Fe (III) compound was clarified. Fe (III) compound reacted with 1-naphthol derivatives such as 5-amino-1-naphthol, 2-nitroso-1-naphthol and 4-chloro-1-naphthol, and salicylic acid to produce color (λmax = 510 nm-565 nm). The evaluation as spectrophotometric determination reagent of Fe (III) compound toward these aromatic compound was investigated. Beer's law was obeyed in a concentration range of 2-10 mg/l of 1-naphthol derivatives and salicylic acid. The determination of 5-amino-1-naphthol and salicylic acid were not interfered up to 100 times concentration of o, m, p-cresol, and the determination of 2-nitroso-1-naphthol and 4-chloro-1-naphthol were not interfered up to 100 times concentration of p-nitrophenol and 2-naphthol in their presence, respectively. It was found that this iron (III) compound could be sufficiently applied at the spectrophotometric determination of 1-naphthol derivatives and salicylic acid.