侵蚀性淋滤液作用下HPMC改性膨润土的防渗性能

Hydraulic performance of HPMC modified bentonites against aggressive solution

使用羟丙基甲基纤维素(HPMC)对天然钠基膨润土进行改性,以提高其对侵蚀性淋滤液的防渗性能.开展渗透试验和膨胀指数试验,以5000mg/L的Cu SO_(4)和0.5mol/L的H_(2)SO_(4)模拟侵蚀性淋滤液,研究侵蚀性溶液对HPMC改性膨润土的渗透系数和膨胀指数的影响.渗透试验结果表明:CuSO_(4)溶液作用下,添加2%和5%的HPMC可使膨润土的渗透系数降低32.28%~77.40%;而H_(2)SO_(4)溶液作用下,添加2%和5%的HPMC可使膨润土的渗透系数降低73.42%~92.83%.膨胀指数试验结果显示,添加2%的HPMC无法提高膨润土在侵蚀溶液中的膨胀指数,但添加5%的HPMC可使膨润土在侵蚀性溶液中的膨胀指数增大2倍左右.HPMC改性可以显著增强膨润土对侵蚀性溶液的防渗性能.孔隙填充是膨润土防渗性能增强的主要机制.

Hydroxypropyl methylcellulose (HPMC) was used to enhance the hydraulic performance of natural sodium bentonite to aggressive solution.Hydraulic conductivity and free swell tests using 5000mg/L CuSO_(4) and 0.5mol/L H_(2)SO_(4) solution were conducted to test the hydraulic performance and swell ability of the HPMC modified bentonite.The hydraulic conductivity test results show that the hydraulic conductivity of the bentonite to CuSO_(4) solution decreased by 32.28%to 77.40%after modification with 2%and 5%HPMC,respectively.Whereas,when permeated with H_(2)SO_(4) solution,the hydraulic conductivity of the bentonite decreased by 73.42%to 92.83%when the mass loading of HPMC was 2%and 5%,respectively.When the HPMC loading reached2%,the swell ability of the bentonite cannot be improved,whereas when the HPMC loading was up to 5%,the swell ability of bentonite can be enhanced by 2factors.These data illustrate that modification with HPMC could improve the hydraulic performance of bentonite to the aggressive solution,and the higher HPMC mass loading the higher hydraulic performance of bentonite.The improvement in the hydraulic performance should be attributed mainly to the clogging of the pore of the bentonite specimens.