两性与两性复配修饰膨润土增强塿土吸附Cr(VI)的研究

Enhanced absorption of Cr(VI) on Lou soil by amphoteric and amphotericcationic modified bentonite

为了证实添加修饰黏土对塿土吸附Cr(VI)的增强作用,分别将2%、5%、8%和10%(质量分数)的200%CEC BS-12(十二烷基二甲基甜菜碱)修饰膨润土(B200B)和100%CEC BS-12+100%CEC DTAB(十二烷基三甲基溴化铵)复配修饰膨润土(B100B/100D)加入到天然塿土,以批处理法研究供试土样对Cr(VI)的等温吸附特征,并对比了p H值、温度和离子强度(I)对Cr(VI)吸附的影响.结果表明:不同B100B/100D塿土(B100B/100D混合塿土)和B200B塿土对Cr(VI)的吸附量分别是CK(塿土)的1.52~4.28和1.99~5.12倍,且等添加比例下B200B塿土对Cr(VI)的吸附量高于B100B/100D塿土.10~30℃范围内,CK、2%B100B/100D和2%B200B塿土对Cr(VI)的吸附呈增温正效应;当修饰土添加比例大于2%时,温度效应由增温正效应向负效应转变.CK对Cr(VI)的吸附量在不同p H值(4~7)处理下差异不显著,而B100B/100D和B200B塿土对Cr(VI)的吸附量均随p H值升高而降低.CK和B100B/100D塿土对Cr(VI)的吸附量均随离子强度(I)的增大而降低,B200B塿土对Cr(VI)的吸附量以I=0.1 mol·L^(-1)时最高,以I=0.5 mol·L^(-1)时最低.B100B/100D和B200B塿土吸附Cr(VI)是自发的物理过程,随修饰土添加比例的增大,吸附表现为焓增、熵减特征.

To examine whether the addition of modified clays can increase the adsorption ability of Cr（ VI） on Lou soil,B200B（ Bentonite modified by 200%CEC BS-12（ dodecyl dimethyl betaine）） and B100 B / 100D（ Bentonite modified by 100% CEC BS-12 and 100% CEC DTAB（ dodecyl trimethyl ammonium Bromide）） were added into Lou soil with the mass fraction of 2%,5%,8% and 10%,respectively. The adsorption characteristics of Cr（ VI） by different Lou samples were studied by batch methods.The effects of p H value,temperature and ionic strength（ I） on Cr（ VI） adsorption were compared.The results indicated that the adsorption capacities of Cr（ VI） on B100 B / 100DLous（ Lou soil mixed with B100 B / 100D） and B200 BLous increased by 1.99 ~ 5.12 and 1.52 ~4.28 times,respectively,as compared with the one of CK（ original Lou soil）. With the same adding proportion,B200 BLous showed higher adsorption capacity t of Cr（ VI） than B100 B / 100 DLous.CK,2% B200 BLou and 2% B100 B / 100 DLou all presented positive temperature effect on Cr（ VI） adsorption in the range of 10 to 30 ℃.When the adding proportion reached 5%,the temperature effect changed from positive to negative. p H had no significant effect on Cr（ VI） adsorption by CK in the p H range of 4 ~ 7,while increasing p H reduced the adsorption capacities of Cr（ VI） by B100 B / 100 DLous and B200 BLous.Besides,increasing I weakened the adsorption capacities of Cr（ VI） by CK and B100 B / 100 DLous,but the highest and lowest capacities of Cr（ VI） adsorption by B200 BLous were obtained at I = 0.1 mol·L^（-1）and I = 0.5 mol·L^（-1）,respectively.Cr（ VI） adsorption by B100 B / 100 DLous and B200 BLous was a spontaneous physical process.The enthalpy increased and entropy decreased with the increase of adding proportion.