摘要
预脱硅-碱石灰烧结法在大幅提高高铝粉煤灰提铝效率的同时副产多孔轻质硅酸钙,而含137Cs+/90Sr2+放射性废水的处理是我国当前核废物处理处置的难题之一。研究了高铝粉煤灰提铝副产物活性硅酸钙对含137Cs+/90Sr2+放射性废水的吸附性能,考察了pH值、活性硅酸钙加入量、时间、温度、137Cs+/90Sr2+初始浓度对吸附率的影响,并对其吸附稳定性进行了详细研究。结果表明,活性硅酸钙对137Cs+/90Sr2+具有较高的吸附性,吸附量随硅酸钙加入量、137Cs+/90Sr2+初始浓度的增加及吸附时间的延长而增大。多孔活性硅酸钙也具有较宽的pH值适应范围,pH值为2~9时,137Cs+的分配系数基本保持不变,约为3 100 mL/g,而90Sr2+分配系数在pH值为1~11时基本保持在1 900 mL/g。活性硅酸钙热稳定性较差,低于500℃时,晶型保持较为完整,600℃保持2 h后非晶化现象严重,700℃后出现新的衍射峰。活性硅酸钙易溶于强酸,其抗浸出性较差。因此,虽然活性多孔硅酸钙对137Cs+/90Sr2+具有较强的吸附性和较强的pH值适应范围,但其稳定性差,不宜用于含137Cs+/90Sr2+放射性废水的处理处置。
Byproduct, porous calcium silicate, will be generated greatly, though A1 extraction rate of high- alumina fly ash can be increased effectively by the pre-desiliconizing and soda-lime-sintering process. On the other hand, the disposal of 137Cs 9~Sr2＋-containing radioactive waste water is one of the tough issues that China has been facing with. Based on these two considerations, in this paper, the adsorption ability of the porous calcium silicate on removing 137Cs＋// 9St2＋ from nuclear waste water was studied, using Cs＋/Sr2＋ to simulate 137Cs＋/9~Sr2＋~ The effect of pH, calcium silicate adding amount, time, tempera- ture, ~37 Cs ＋/9~Sr2 ~ initial concentration were discussed in details and the stability of 137 Cs ~/ 9~Sr2＋ ad- sorbed calcium silicate was also investigated. The results indicate that calcium silicate shows a higher ad- sorption to 137Cs ~/~~Sr2~ , and its adsorption amount increases as the increase of time, calcium silicate adding amount and 137Cs ＋/9~Sr2 ~ initial concentration. Calcium silicate also possesses a wide pH adapta- tion. The distribution coefficient of 137Cs＋ and 9Sr2 is 3 100 mL/g and 1 900 mL/g in the range of 2 -9 and 1 - 11, respectively. Calcium silicate phases keep well when the temperature is lower than 500℃. At 600 ℃, it shows a non-crystal phenomenon. When the temperature is higher than 700 ℃, new diffraction peaks emerge, indicating the formation of new phases. Calcium silicate can be totally dissolved in strong acid. GB 7023 -86 results prove that calcium silicate shows a considerably low anti-leaching stability. Therefore, though the activated, porous calcium silicate show a relati,Jely high adsorption to 137 Cs ＋/90 Sr2 ＋ , it is not feasible to disposal 137 Cs ＋/90Sr2-containing radioactive waste water by this byproduct.
出处
《西南科技大学学报》
CAS
2013年第3期1-6,15,共7页
Journal of Southwest University of Science and Technology
基金
国家自然科学基金项目(21007052)
关键词
活性硅酸钙
放射性废物
吸附
稳定性
Activated calcium silicate
Nuclear waste
Adsorption
Stability
