有机修饰(土娄)土对CrO_4^(2-)吸附特征的初步研究

CrO_4^(2-) ADSORPTION CHARACTERISTICS OF LOU SOILS MODIFIED WITH ORGANIC SUBSTANCES

以CTMAB(十六烷基三甲基溴化铵)单一修饰和CTMAB+SDS(十二烷基磺酸钠)混合修饰土耕层、粘化层土样,从修饰比例、土层、温度角度探讨了有机修饰土对CrO42-的平衡吸附特征。结果表明,各供试土样中CrO42-平衡吸附量均随CrO42-平衡浓度增高而增大,有机修饰土对CrO42-的吸附等温线呈现L型等温线形式,原土土样的吸附等温线基本上类似于S型吸附等温线形式,两层次各土样对CrO42-的吸附量呈现100CB>120CS>50CB>CK的顺序(100,120,50分别表示修饰比例为100,100+20,50;CB为CTMAB修饰;CS为CTMAB+SDS修饰;CK为未修饰原土);随着平衡浓度的增大,耕层原土对CrO42-的吸附能力增加较快而粘化层原土增加较慢,土粘化层修饰土样对CrO42-的平衡吸附量均高于土耕层土样,但修饰比例增高导致两层次土样对CrO42-吸附亲和力的差异减小;未修饰原土对CrO42-吸附呈现增温效应,粘化层CK土样增温效应高于耕层CK土样,表明增温促进粘粒矿物对CrO42-的专性吸附。随平衡浓度的增大,修饰土样CrO42-吸附温度效应比值均变化不大,耕层各修饰土样对CrO42-吸附呈现增温负效应,而粘化层修饰土样对CrO42-吸附的温度效应则与修饰剂和修饰比例有关。

From the angles of modification rate, soil layers, and temperature, CrO4^2- adsorption characteristics were studied of the soil samples gathered from the tillage layer （TLLS） and clay layer of lou soil （CLLS） modified with cetyhrimethylammonium bromide （CTMAB） and cetyhrimethylammonium bromide ＋ sodium dodecylsulphonate （ CTMAB ＋ SDS） mixture at various rates. The results show that CrO4^2- equilibrium adsorption amounts （EAA） in the soil samples increased with the CrO4^2- equilibrium concentration; the adsorption isotherms appeared in the shape of L in the modified soils and of S in the unmodified soil. In terms of adsorption of CrO4^2- the soil samples from both layers were in the order of 100CB 〉 120CS 〉 50CB 〉 CK. CrO4^2- adsorption in unmodified TLLS increased faster than that in unmodified CLLS with the increase in CrO4^2- equilibrium concentration. The EAA of CrO4^2- in modified CLLS were higher than that in modified TLLS, however, the difference in soil affinity to CrO4^2- between modified CLLS and modified TLLS decreased with the increase in modification rate. CrO4^2- adsorption in unmodified soils increases with the temperature, and the effect was stronger on unmodified CLLS than on unmodified TLLS, indicating increase in temperature promotes CrO4^2- special adsorption on clay mineral. The CrO4^2- adsorption rate from 20℃to 40℃ on modified soils did not vary much with the increase in CrO4^2- equilibrium concentration. With rise in temperature, CrO4^2- adsorption on modified TLLS decreased while the CrO4^2- adsorption on modified CLLS was related to both modifier and modification rate.