Studies On The Complex Modification Of Bentonite With BS-12+Tween

With the development of industry and agriculture, water pollution presents the trends that with heavy metals and organic compound contamination. The amphoteric modified bentonite which is modified by BS-12 has the effect to the simultaneous adsorption of heavy metals and organic compounds. As the adsorption effect of amphoteric compound modified soil is better, the researchments that studied the modified the conditions and mechanism by modified bentonite to BS-12 and Tween class of nonionic modifier complex modifications have the practical significance.This paper made a high degree of swelling and a high specific surface bentonite as the substrate to study the absorption efficiency and the adsorption mechanism of the BS-12, and the batch processing isothermal balance adsorption method was used to study it in different pH, temperature and ionic strength conditions. And it made the BS-12 amphoteric modified bentonite. The BS-12 amphoteric modified bentonite characterized the physical and chemical properties by TOC, BET, XRD and FTIR; Batch processing method was used to research the adsorption that BS-12 organic modified bentonite to Tween 20, Tween 40 and to Tween 80. Meanwhile, the influence of pH, temperature and ionic strength on adsorption was investigated. The purpose was to through the adsorption isotherm; the adsorption properties and modification mechanism of amphoteric-nonionic compound modification under different modification ratios and various conditions were discussed, to provide a theoretical and practical basis for organic modified bentonite’s adsorption of pollutants.The paper obtained conclusion was as follows:(1) The results of BS-12 bentonite’s compound modification of XRD, BET and FTIR showed that the characteristics of the structure by the BS-12 after the modification of bentonite, BS-12 had entered into between the layers of bentonite. In different modified proportion, the amphoteric surface BS-12 had two different ways to modify the bentonite: When the proportion of modification was less than 100%CEC, BS-12 mainly through electrostatic adsorption and cation exchange effect by intercalating into bentonite clay interlayer; With modified ratio increased, BS-12 to intercalated into the interlayer was no longer the major modification of bentonite, there were more BS-12 in the solution combine the BS-12 that was adsorbed on bentonite by hydrophobic key form, then it adsorbed on the external surface of the bentonite in turn. Both of the content of organic carbon, organic modified soil specific surface area and layer spacing have the relationship with the proportion of modification amphoteric modifier: with the increasing of BS-12, the content of organic carbon, soil modified kind of layer spacing was increasing while the specific surface area was decreasing.(2)The results showed that the adsorption quantity increases with the rise of equilibrium concentration which conforms to Langmuir Model. When pH was higher, the adsorption that bentonite to BS-12 was lower; and a higher temperature made the adsorption higher; a larger ionic strength can inhibited the increase of the bentonite adsorption. The optimum condition of BS-12 adsorption on bentonite was at more than 3 h, pH was 1.0, temperature was 40℃ and ionic strength was 0.001 mol·L-1.(3)The results of BS-12 bentonite’s compound modification of Tween 20 showed that the equilibrium adsorption capacity of amphoteric modified bentonite of Tween 20 was negatively correlated with the modification ratio of BS-12. BS-12 modified bentonite showed that the adsorption isotherms of Tween 20, in pH 2.0 on Tween higher adsorption capacity of 20; temperature had little effect on the adsorption quantity of Tween 20, temperature was slightly promote the adsorption of Tween 20, 40℃ was the best modification temperature; increasing ionic strength had an inhibitory effect on the adsorption of Tween 20. The optimum concentration of KNO3 was 0.01 mol·L-1. The adsorption isotherm of BS-12 bentonite of Tween 20 indicated that when pH 2.0, the adsorption of BS-12 bentonite of Tween 20 was the most; temperature had little effect on the adsorption quantity of Tween 20, temperature will be slightly promote the adsorption of Tween 20,40℃ was the optimum modification temperature; A larger ionic strength can inhibit the increase of Tween 20 adsorption. The concentration of KNO3 was the optimum modification concentration. The adsorption quantity of BS-12 bentonite of Tween 20 and Tween 80 increased with the rise of equilibrium concentration conformed to Langmuir Model. and on the adsorption of Tween 40 was increased firstly and then decreased, with the BET model. In 50 BS and 100 BS bentonite adsorption on the order of Tween 20 > Tween 80 > Tween 40, sequential adsorption in 150 BS bentonite was Tween 80 > Tween 20 >Tween 40.