粉煤灰-粉煤灰合成沸石对Cs~+的固化

以电厂废弃物粉煤灰为原料、采用碱熔-水热法制备了粉煤灰合成A型沸石(以下简称沸石),再以沸石对溶液中的Cs+进行分离富集,最后在碱激发剂的作用下以粉煤灰和吸附后的沸石制得地聚合物固化体。对固化体的性能进行了评价,并探讨了固化机理。实验结果表明:在吸附温度25℃、初始Cs+质量浓度100 mg/L、固液比10.0 g/L的条件下,沸石对的Cs+的吸附率达98%,比粉煤灰提高了2倍以上;沸石掺量为20%~30%(w)时,固化体的抗压强度符合GB 14569.1—2011要求,固化体中Cs+的42 d浸出率和累计浸出分数均远优于GB 14569.1—2011限值,表现出优异的抗浸出性能。

Solidification of Cs+ in fly ash and zeolite synthesized from fly ash

The synthetic zeolite-A was prepared by alkali fusion-hydrothermal method using waste fly ash in power plant as raw material. The zeolite was used to isolate and enrich Cs+ in solution,and then to form geopolymer solidified body with fly ash under the effect of activator. The performances of the solidified body were evaluated and the soidificaton mechanism was discussed. The experimental results show that:Under the conditions of adsorption temperature 25℃, initial Cs+ mass concentration 100 mg/L and solid-liquid ratio 10.0 g/L,the equilibrium adsorption rate of Cs+ on the zeolite is reached 98%,which ismore than 2 times higher than that on fly ash;When the zeolite dosage is 20%-30%(w),the solidified body exhibits excellent leaching resistance performances,the compressive strength of the solidified body meets the requirement in GB 14569.1-2011,and the leaching rate and accumulated leaching fraction of Cs+ in the solidified body are far lower than the standard limits in GB 14569.1-2011.