[TG-FTIR analysis of thermal degradation of bischofite's crystals with aniline hydrochloride].

The dehydration of bischofite is the key to the use of magnesium resource. Double salts or complex method is an important way to prepare anhydrous magnesium chloride. The crystals of bischofite and aniline hydrochloride were prepared through lowering the temperature of the mixture's aquatic solution slowly. The pyrolysis of aniline hydrochloride, bischofite and the crystals was qualitatively analyzed by TG-FTIR under 400 degrees C. We infered the reaction process through qualitative detection of escaping gas of each decomposition step. The Experimental results showed that there were three steps in the thermal decomposition of bischofite. In the first step, nearly four crystallized waters decomposed, while hydrolysis and decomposition took place together in the next two steps, but hydrolysis was the main reaction at the lower temperature (205-235 degrees C), and comparative decomposition was the main one at the higher temperature (235-287 degrees C). In the experimental temperature range, aniline hydrochloride didn't decompose. Water and aniline hydrochloride left the crystals at different temperature, and no hydrolysis reaction occurred. Anhydrous magnesium chloride can be prepared though this way.

[Radiolysis of aqueous solution of thiocyanate by gamma-rays].

Radiolysis of aqueous solution of thiocyanate by 60Co gamma-rays was studied. In condition of pH = 1 and pH = 3,25 mg/L SCN- was decomposed under the dose of 6 kGy, with decomposition rate of 98.11% (pH = 1) and 95.97% (pH = 3) respectively. 25 mg/L SCN- (pH = 7) was decomposed under the dose of 9 kGy and the decomposition rate is 99.33%. In the alkaline condition, pH = 10 and pH = 12, the dose of 18 kGy was need, and the decomposition rate is 99.64% and 99.93% respectively. High SCN- concentration means that more radiation dose is need. From the comparison of before radiolysis and after radiolysis's TOC (total organic carbon) and TN (total nitrogen) of SCN- solution, little TOC and TN was removed. The determination of SO4(2-) and NO3- concentration indicated that sulfur element was removed and converted to SO4(2-), and nitrogen element rarely converted to NO3-, but converted to other forms of nitrogen.

[Radiolysis of aqueous thiocyanate and its complicated system].

We studied the 60Co gamma-ray radiolysis of thiocyanate aqueous solutions in the presence of free radical scavengers, determination of cyanide of radiated thiocyanate solutions, degradation of cyanide and thiocyanate complicated system and cyanide, thiocyanate and copper (I) cyanide complicated system. The presence of NaHCO3 and n-butanol made the degradation efficiency of thiocyanate decreased, in the radiation procession of thiocyanate, cyanide was produced; and the possible reaction equation is SCN(-) + 8*OH-->SO4(2-) + CN(-) +4H2O, in the cyanide and thiocyanate system, the thiocyanate degradation rate can obtained 30%, free cyanide degradation was little effected by coexistence of thiocyanate; and due to strong complex ability of copper (I), the main form of copper (I) cyanide is Cu(CN)3(2-), the total cyanide of the system can't be degraded completely and degradation rate is about 80%.