Study On Cr(Ⅵ) Adsorption Properties Of Gemini Surfactant-modified Activated Carbon Adsorbent

Involving chromium industry produce large amounts of highly toxic hexavalent chromium-containing industrial waste water every year. Untreated wastewater containing chromium into the environment pose a great risk to people and animals and plants, therefore, it’s very important to deal with wastewater containing chromium. However, the adsorption has a high removal efficiency, chemical sludge reduction, easy operation, temperature adaptability advantages. At present, the introduction of surfactant modified activated carbon was small, and Gemini surfactant modified activated carbon in China has not.Therefore,surfactants modified adsorbent for heavy metal adsorption applications, theoretical researchhave yet to be perfected.Proposed use of Gemini surfactant PDDDAB preparation technology of modified activated carbon, with their corresponding normal surfactant DTAB properties of modified activated carbon compare. Study results suggest that Gemini surfactant-modified activated carbon significantly enhanced activated carbon adsorption of chromium on. Major findings are as follows:1. Has prepared9types of modified activated charcoal, through experiments of their adsorption capacity of hexavalent chromium are: PDDDAB>PDODAB>DTAB>EDDDAB>EDODAB> not modified activated carbon>DPB>RS>SDS>HAPPE。Modified by Gemini surfactant PDDDAB activated carbon for the adsorption of chromium removal improves67.2%. General surfactant DTAB modified activated carbon for the adsorption of chromium removal improves41.3%.2. The concentration of the modifier is within the range of0.1%to10%.The gemini surfactant PDDDAB modified activated carbon adsorption of chromium removal rate increases linearly with the increase in the concentration of modifier;When the modifier concentration of5%, DTAB modified activated carbon adsorption removal of chromium increasing trend is very small.3. In the case of the same adsorbent concentration, the gemini surfactant PDDDAB modified activated carbon adsorption of chromium removal and adsorption is much higher than conventional surfactants DTAB modified activated carbon.And the adsorbent concentration is greater, the greater the removal rate of chromium, but the adsorption amount decreases continuously.4. Gemini surfactant modified activated carbon adsorption performance is more stable. The gemini surfactant PDDDAB modified activated carbon in the reaction for30minutes or so to achieve maximum removal rate of92%,The DTAB modified activated carbon in the reaction lmin maximum removal rate of70%;As the reaction proceeds, the two removal rate began to decline, the removal rate decreased by6%and20%.5. The chromium compound in the modified carbon surface subjected to ion exchange is the main mechanism of Cr (VI) anion can be removed;Two activated carbon adsorption of chromium removal rate decreased with increasing ionic strength solution.6. The gemini surfactant PDDDAB modified activated carbon are more able to adapt to changes in pH.When the PH value of3to4, the two adsorbents have the highest removal rate,With the pH value increases, the removal rate of decline.However, at any pH value, the effect of PDDDAB modified activated carbon always than DTAB modified activated carbon。 The rate of decline is slow than DTAB modified activated carbon。7. Langmuir, Freundlich isotherm model to fit the the two adsorbent experimental data.The results showed that the two adsorbent chromium adsorption isotherm is more in line with the Freundlich isotherm model, the two adsorbent adsorption of chromium uniform monolayer adsorption.8. Using lagergren pseudo-first order adsorption rate equation, Lagergren pseudo-second adsorption rate equation fit the experimental kinetic data of two adsorbent. The results show that the two modified activated carbon adsorbent for the adsorption of chromium more in line with the pseudo-second adsorption rate equation.