RESUMO
The anhydrite and gypsum are the main sulfate minerals during evaporation of seawater or lake.They record the information about relative hydrogeology and the composition of mother liquor.Boron is diffluent element, and often occurs in all kinds of evaporites.Presently, the boron isotope has been applied widely in mineral deposits forming, geochemistry and palaeoenvironment.However, there is little research about characteristic of boron isotope in anhydrite and gypsum minerals, because of the low content of boron and micro-solubility in water and hydrochloric acid.This study developed a method of extracting and purifying boron in anhydrite and gypsum by phase transformation and ion-exchange.Firstly, the samples were mixed with ammonium hydrogen carbonate to transform the calcium sulfate to calcium carbonate.And diluted hydrochloric acid (1 mol/L) was added to resolve calcium carbonate.The percent conversion was about 85%in the first stage, and up to complete resolution by repeating this process.Secondly, boron specific ion-exchange resin ( Amberlite IRA 743 ) was used to gather the boron ions fully and further refined the samples with more than 1 μg of boron by anionic and cationic resin mixed by Ion Exchange Ⅱ and Dowex 50 W × 8.Finally, according to the modified method by He, the values of boron isotope were determined by TIMS.The boron content is analytically pure gypsum was 3.501 ± 0.128 μg/g ( n=12 , RSD=3.6%) and the average recovery was 100.47%.Besides, the δ11B value of analytically pure gypsum added with NIST SRM 951 was 17.98‰±0.21‰ (n=3, RSD=1.2%).This method has good repeatability and can meet the requirements of boron isotopic measurement of anhydrite and gypsum.
RESUMO
Objective To select an efficient ion exchange resin to purify the 60Co contaminated well-water for storing radioactive source and to ensure the radioactivity of 60Co in treated well-water below 10 Bq/L.Methods The radioactivity of 60Co in the water samples was measured by using the potassium cobaltinitrite coprecipitation-β counting method.The treatment efficiencies of two different ion exchange resins for the simulated 60Co-bearing waste water were compared to select a better one to dispose of the 60Co contaminated well-water.Results The treatment efficiency of MBD-15-SC mixed ion exchange resin was about 5.8 times higher than ZGCNR50 strong-acid cation exchange resin.The radioactivity of 60Co in the contaminated well-water could be reduced from 4.16 × 105 Bq/L to 1.16 Bq/L by two-stage sorption of MBD-15-SC mixed ion exchange resin.Conclusions Using several times of two-stage MBD-15-SC mixed ion exchange resin could effectively purify the 60Co contaminated well-water.The quality of the treated well-water could meet the sewage discharge standards.