Slaked lime with ultrafine particles could be efficiently adsorbing hydrogen chloride gas, which was discharged from the garbage incineration plants. This study was made to investigate about the synthetic condition and formation mechanism of slaked lime with ultrafine particles formed by adding saccharides solution to quick lime. Slaked lime with ultrafine particles was synthesized by adding saccharides solution to quick lime with particle size of 300-500 μm. The sample was characterized by means of X-ray diffraction, measurements of specific surface area and particle size distribution. The hydration rate of quick lime was controlled by adding saccharides into water. The specific surface area of slaked lime formed under the condition controlled most hydration was attained to high value. For example, the specific surface area of slaked lime which was formed under synthetic condition of sucrose /CaO mass ratio 0.03 was approximately 43 m2. g-1. The slaked lime with ultrafine particles was formed aggregate with diameter of 2.6 μm. The aggregate had pore size distribution with 2-4 nm and range of 30-100 nm. Also, the formation mechanism of slaked lime with ultrafine particles by adding saccharides solution was discussed.
Synthesis of sodium magnesium phosphates by an oxidative decomposition method of EDTA-metal chelate with hydrogen peroxide were investigated. Three new compounds and trimagnesium phosphate pentahydrate (TMP5) were obtained. These compounds are NaMg7 (PO4) 5·12H2O (described as NNa-1), NaMg2 (PO4) (HPO4) ·3H2O (described as NNa-2) and NaMg4 (PO4) 3·6H2O (described as NNa-3), and these structures are orthorhombic, monoclinic and orthorhombic (or monoclinic), respectively. These compounds are obtained by controlling the concentrations of Na+, Mg2+ and oxo-phosphate ions as mono phase of each compound. NNa-1 was successfully obtained by allowing to react the solution with the conditions of high pH, R value (Mg2+ /PO43- molar ratio) =1.0 and lower concentration of sodium ion, NNa-2 was obtained under the condition of R value = 0.1, and NNa-3 was obtained under the conditions of R value=1.0 and higher concentration of sodium ion.
Regeneration methods of Mg-Al-Cl form hydrotalcite-like ion exchanger for selective adsorption of phosphate anion were investigated. It was possible to regenerate the reusable exchanger with high efficiency by the two-step regeneration method consisting of the treatment with a mixture of 0.25 mol ·kg-1-NaOH and 6.00 mol·kg-1 NaCl solution at the first step, followed by that with 3.68 mol·kg-1 MgCl2 solution. The exchanger could be used for removal of phosphate ion with regeneration ratio of 50% even after nine times reuse. The regeneration ratio of the exchanger with granular form was examined in a flow system and found to be almost equal to 100% using the two-step regeneration method. The break-through capacity of the flow system was more than those of well-known zirconium ferrite type adsorbents even after six times runs.
Several organic ultraviolet (UV) -absorbents such as 4-hydroxy-3-methoxybenzoic acid (HMBA), 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (HMBSA), 4-hydroxy-3-methoxycinnamic acid (HMCA), 4, 4'-diaminostilbene-2, 2'-disulfonic dcid (DASDSA), p-aminobenzoic acid (PABA) and urocanic acid (UA) were intercalated into Zn2Al layered double hydroxides (Zn2Al-LDHs) by anion-exchange and/or co-precipitation and the photochemical properties of the nanocomposites materials obtained were investigated. The UV ray absorption ability of the organic UV absorbents increased and their catalytic activity for the air oxidation of castor oil greatly decreased when they were intercalated into the interlayer spaces of the Zn2Al-LDHs.