Studies On The Preparations Of Amphoteric-complex-modified Kaolin

In recent years, with the development of industrial and agricultural production, large quantities of pollutants are discharged into the environment, and the soil has become the ultimate recipient of these pollutants, soil organic matter, heavy metals contamination gradually become the main form of soil pollution. Since the hydrophilic clay mineral surface limit its adsorption of organic pollutants, hence, modified clay minerals had potential to control soil pollution. Kaolin as the main component of the soil clay mineral particles, it is of practical significance to investigate its amphoteric surface modification and amphoteric compound modified, and explore the amphoteric compound modified kaolin to absorb heavy metal and organic compound pollution.This paper using kaolin modifying the original soil and amphoteric surfactants sodium dodecyl dimethyl betaine(BS-12) modified kaolin as matrix, studied BS-12 modification of kaolin and cationic surface modifying agent Cetyltrimethyl ammonium bromide(CTMAB) to BS-12 gender-modified kaolin complex modifications and CTMAB in the complex process of modification of BS-12 modified kaolin stability in different pH, temperature, ionic strength under conditions of single factor. The aim is to explore the BS-12 and BS-12+CTMAB complex modification of kaolin and modification mechanism, so as to gender-cationic surface modifier complex to adsorb contaminants modified kaolin, and provide a theoretical basis.The main conclusions of the paper obtained as follows:Gender modified in BS-12 Preparation of kaolin,1. kaolin adsorption of BS-12 corresponded to the model of the Freundlich, which belonged to spontaneous reaction.2. Factors study showed that, in the same amount of adsorption equilibrium concentration, the trend of pH was pH4>pH6>pH7>pH8>pH10, under acidic conditions favor kaolin adsorption of BS-12. The adsorption equilibrium in the same concentration increased with temperature, 30℃>40℃>10℃>20℃, and the temperature rose in favor of kaolin adsorption of BS-12. Besides 0.5mol·L-1 with greater impact, ionic strength of kaolin of adsorption BS-12 showed less effect, 0.001molL-1>0.01 mol L-1>0.1mol L-1, but the difference was obvious.3. The best conditions for the preparation of amphoteric modified kaolin: pH 4.0, temperature 30℃, ionic strength 0.001 mol L-1.4. Under low concentrations, BS-12 mainly combined by electrostatic attraction of the surface modification of kaolin, with increasing concentration, gradually changed to a hydrophobic bonding mode kaolin surface modification.Cationic surface modifier complex CTMAB modified kaolin modified BS-12 study,1. BS-12 modified kaolin CTMAB adsorption kinetics curves also showed rapid adsorption and slow absorption features two stages of adsorption at 36 h basically balanced.2. BS-12 modified kaolin CTMAB of the Freundlich adsorption distribution model, the thermodynamic parameters ?G was less than zero, adsorption belonged to spontaneous reaction.3. Effect of different conditions on the BS in the modified kaolin CTMAB adsorption, pH Adsorption on CTMAB was not obvious, in low pH, CTMAB adsorption benefited. The trend of adsorption equilibrium concentration at the same temperature dependence was approximately 40℃>20℃>10℃>30℃. Overall, the adsorption CTMAB was beneficial to higher temperature. Ionic strength effects on adsorption BS-12 kaolin results showed 0.001mol·L-1>0.1 mol·L-1>0.01mol·L-1>0.5mol·L-1, the lower the ionic strength, more CTMAB adsorption.4.BS-12+CTMAB complex modification of kaolin optimum conditions were time 36 h, pH 4.0, ionic strength of 0.001 mol L-1KCl, temperature of 40℃.5. Under the same conditions, the adsorption of CTMAB original soil was always higher than the BS-12 modified kaolin. Under the same pH, ionic strength, 50 BS kaolin adsorption of CTMAB was higher than 100 BS kaolin, while at the same temperature, 100 BS kaolin adsorption of CTMAB was overall higher than 50 BS kaolin.In the desorption of kaolin BS-12’s complex modifiers gender modification of CTMABTemperature, pH, ionic strength conditions have little effect on the BS-12 desorption, as well as the CTMAB modified ratio, 6% less than the maximum desorption. BS-12 modifiers and kaolin solidly combined, and the kaolin surface adsorption was irreversible. CTMAB in complex modification process was difficult to cause the desorption of BS-12.