氯盐溶液对钠基膨润土垫层膨胀性能的影响

Influence of chlorine salt solution on swelling properties of sodium bentonite cushion

在废弃物渗透液中,复杂的化学物质能影响钠基膨润土垫层的吸水膨胀性能,研究不同价态及浓度的氯盐溶液对膨润土膨胀指数的影响,探究pH值及温度对膨润土膨胀性能的影响,利用X射线衍射仪及扫描电子显微镜对氯盐溶液处理后的膨润土进行表征分析。试验结果表明,高价态高浓度的氯盐溶液对膨润土的膨胀性能起抑制作用,膨胀指数最低为5 mL/2 g;单价态低浓度的NaCl溶液对膨润土的膨胀性能起促进作用,膨胀指数最高达到56 mL/2 g。XRD测试表明,氯盐溶液处理后的膨润土层间距由12.512A下降到11.856A;SEM测试分析发现,高价态氯盐溶液中的膨润土形貌由规则鳞片状转化为无规则絮凝状。在氯盐溶液浓度为0.04 mol/L、pH值为9及温度为90℃的条件下,膨胀指数提升近50%。在0.01 mol/L NaCl溶液、0.02 mol/L NaCl溶液和0.01 mol/L CaCl_(2)溶液中,膨润土吸水膨胀过程中凝胶态部分符合Fickian扩散模型,表明溶液水分子扩散速率小于膨润土凝胶态部分松弛速率。其他浓度氯盐溶液中,膨润土吸水膨胀过程中凝胶态部分符合non-Fickian溶胀过程,溶液水分子扩散速率与膨润土凝胶态部分松弛速率大致相同。

Since the complex chemical substances in the waste permeate can affect the water-absorbing swelling performance of the sodium bentonite cushion,this paper studies the influence of different valences and concentrations of chlorine salt solutions on the swelling index of bentonite.At the same time,the influence of pH value and temperature on the swelling performance of bentonite was explored,and the bentonite treated with chlorine salt solution was characterized and analyzed by X-ray diffractometer and scanning electron microscope.The test results show that the high-valence and high-concentration chlorine salt solution inhibits the swelling performance of bentonite,and the swelling index is at least 5 mL/2 g.The monovalent lowconcentration NaCl solution improves the swelling performance of bentonite,and the swelling index reaches a maximum of 56 mL/2 g.XRD test shows that the bentonite layer spacing after chlorine salt solution treatment decreases from 12.512A to 11.856A.SEM test analysis find that the morphology of bentonite in the highvalence chlorine salt solution changes from regular scaly to irregular flocculation.In 0.01 mol/L NaCl solution,0.02 mol/L NaCl solution and 0.01 mol/L CaCl_(2) solution,the gel state part of the bentonite in the process of absorbing water and swelling conforms to the Fickian diffusion model,it shows that the diffusion rate of water molecules in the solution is less than the relaxation rate of the gel state of bentonite.The gel part of bentonite in the swelling process of water absorption and swelling in chloride salt solutions of other concentrations conforms to the non-Fickian swelling process,and the diffusion rate of water molecules in the solution is approximately the same as the relaxation rate of the gel part of bentonite.