蒙脱石电渗微观机理试验研究

Experimental study on micro-mechanism of electro-osmosis using montmorillonite

为了在微观上探究电渗的作用机理,以单一矿物成分的蒙脱石为电渗对象,采用自制金属电极和EKG电极,设计4组平行试验,探讨土体离子迁移、电学参数、膨胀性能等物理化学方面的变化.试验结果表明,Al^(3+)迁移能力远大于Cu^(2+)和Fe^(2+),后两者难以在电场力的作用下移动,电极反应生成的金属离子对电渗排水基本没有促进作用;电渗削弱了蒙脱石的乙二醇膨胀性,且除铜电极外,铝、铁、EKG电极下电渗对靠近阴极的土的膨胀性抑制作用更强;电渗作用降低了蒙脱石的zeta电位绝对值;铝电极下Al^(3+)的渗入严重降低了Ca^(2+)的排出量,铁电极下Fe^(3+)和Fe^(2+)的渗入束缚了阳极附近土体中Na^+的迁移;铁电极和EKG电极对土体有酸化作用,而铜电极、铝电极则不然.

Single mineral montmorillonite was taken as electro-osmosis object to explore the microcosmic mechanism of electro-osmosis.Four sets of parallel tests were designed using self-made metal electrodes and EKG(electro-kinetic geosynthetics)electrodes.The results of electro-osmosis were analyzed;the changes of the physicochemical aspects such as ion migration,electrical parameters and swelling properties were discussed.The experimental results show that Al^(3+) migration ability is much greater than Cu^(2+) and Fe^(2+),the latter two are difficult to move under the action of electric field force,the metal ions produced by the electrode reaction have little effect on the electro-osmotic drainage;the electro-osmosis weakened the ethylene glycol expansibility of montmorillonite,and in addition to the copper electrode,electro-osmosis under the aluminum,iron,EKG electrode has stronger inhibition on the expansion of soil near the cathode;the electro-osmotic effect reduced the absolute value of zeta potential of montmorillonite;the infiltration of Al^(3+) in the aluminum electrode seriously reduced the emission of Ca^(2+),and the infiltration of Fe^(3+) and Fe^(2+) in the iron electrode constrained the migration of Na^+ in the soil near the anode.The iron electrode and the EKG electrode have acidification effect on the soil,while the copper and aluminum electrodes are not so.