添加复合吸附剂对塿土吸附菲和Cr(Ⅵ)的影响

Effect of Adding Compound Adsorbent on Phenanthrene and Cr(Ⅵ)Absorption by Lou Soil

为了探究添加复合吸附剂对土吸附菲和Cr（Ⅵ）的影响,采用玉米秸秆生物炭和200%CEC十二烷基二甲基甜菜碱（BS-12）修饰膨润土（B200B）以质量比（1∶2）、（1∶1）和（2∶1）组配为3种复合吸附剂（CS（1∶2）、CS（1∶1）和CS（2∶1））,将其以不同添加量（2%、5%和10%）加入塿土,批处理法研究各土样对菲和Cr（Ⅵ）的等温吸附,并对比不同pH值和温度对吸附的影响.结果表明∶1添加复合吸附剂的土（CS塿土）对Cr（Ⅵ）的吸附量是CK（塿土）的3.02-13.61倍,且等添加量下Cr（Ⅵ）吸附量表现为CS（2∶1）〉CS（1∶1）〉CS（1∶2）〉CK.吸附为自发过程,表现为焓增（CS（1∶2）除外）、熵增的特征.不同CS塿土对菲的吸附量为CK的3.87-13.00倍.2%和5%添加量下,菲的吸附量表现为CS（1∶2）〉CS（2∶1）〉CS（1∶1）〉CK,而菲吸附量在10%添加量下为CS（1∶2）〉CS（1∶1）〉CS（2∶1）〉CK.吸附表现为自发、焓减和熵增的特征.210-30℃范围内,CK、CS（1∶1）和CS（2∶1）塿土对Cr（Ⅵ）的吸附量增加了5.84%、4.63%和8.22%,而CS（1∶2）塿土对Cr（Ⅵ）的吸附量降低2.70%.CK对菲的吸附量从10-30℃增加1.69%,CS（2∶1）、CS（1∶1）和CS（1∶2）土对菲的吸附量分别降低了10.55%、4.36%和12.81%.3pH值4-10,CK对Cr（Ⅵ）的吸附无显著变化,而各CS塿土对Cr（Ⅵ）的吸附量随pH值增大而降低.CK、CS（1∶2）和CS（1∶1）塿土对菲的吸附量在pH=4最大,而CS（2∶1）塿土对菲的吸附量在pH=7最大.4复合吸附剂中B200B比例越高,CS塿土对菲的吸附越佳,而生物炭比例越高,CS塿土对Cr（Ⅵ）的吸附越好.

To study the effect of the addition of compound adsorbent on the phenanthrene and Cr（ Ⅵ ） adsorption of Lou soil, biochar （made from corn stover） and B200R （Bentonite modified by BS-12, dodecyl dimethyl betaine with modified ratio of 200% CEC of Bentonite） were mixed at mass ratios of 1：2, 1：1 and 2：1 as the compound adsorbents （CS1：2, CS1：1 and CS2：1 ）. Different amounts （2%, 5% and 10% ） of these three compound adsorbents were added into Lou soil. Batch method was used to analyze the phenanthrene and Cr（ Ⅵ ） adsorption isotherms of different Lou samples, and compare the effect of environmental conditions such as pH value and temperature on the phenanthrene and Cr（Ⅵ ） adsorption. The results indicated： （1） Adsorption amounts of Cr（ Ⅵ ） on different Lou samples were 3.02 to 13.61 times higher than CK （ original Lou soil）. Under the same adding conditions （amount） , Cr（ Ⅵ ） adsorption showed the order of CS2：1 Lou 〉 CS1：1 Lou 〉 CS1：2 Lou 〉 CK. Cr（Ⅵ） adsorption was a spontaneous process with decreased enthalpy （except CS1：2 ） and increased entropy. Adsorption amounts of phenanthrene on different Lou samples were 3.87 to 13.00 times higher than CK. Phenanthrene adsorption presented the ranking of CS1：2 Lou 〉 CS2：1 Lou 〉 CS1：1 Lou 〉 CK at the adding amounts of 2% and 5% , while showed the order of CS1：2 Lou 〉 CS1：1 Lou 〉 CS2：1 Lou 〉 CK when 10% of the compound adsorbent was added. The adsorption was also a spontaneous process with decreased enthalpy and increased entropy. （2） When the temperature was 10-30℃ , the adsorption amount of Cr（Ⅵ ） increased by 5.84% , 4.63% and 8.22% on CK, CS1：1 and CS2：1 Lou soils, and reduced by 2.70% on CS1：2 Lou soils. Adsorption amount of phenanthrene increased by 1.69% of CK and reduced by 10. 55% , 4.36% and 12.81% of CS2：1 , CS1：1 and CS1：2 Lou soils respectively. （3） When the pH was 4-10, the Cr（Ⅵ） adsorption had no significant change for CK, while those for CS1：2, CS1：1 and CS2：7 Lou soils all reduced. Phenanthrene adsorption of CK, CS1：2 and CS1：1 Lou soils was all highest at pH = 4, and phenanthrene adsorption of CS2：1 Lou was highest at pH = 7. （4） The higher the ratio of B200B in compound adsorbent, the better the phenanthrene adsorption was. The higher the ratio of biochar in compound adsorbent, the better the Cr（ Ⅵ ） adsorption was.