| At present, Cr6+ in some life drinking water has far exceeded national standard level, sometimes as high as 0.1～3 mg/L according to the survey. It was largely because of industrial waste water pollution and the change of geological background. It has brought huge impact to the health and daily life of the local people. It can lead us poisoning when the. content of Cr6+ is more than 0.1 mg/L. Chromium has been identified as carcinogens.In this paper, first we used different methods to modify the adsorbent-activated carbon, zeolite and attapulgite. We compared the removal efficiency of Cr6+ which was adsorbed by the modified adsorbent and we found that modified activated carbon can remove Cr6+ better. Then we used different methods to modified activated carbon and found that the activated carbon which carbonized modification have the better adsorption effect to Cr6+than others. Through a series of experiments, we analyzed the various factors on the removal efficiency of Cr6+, and preliminarily studied on its adsorption mechanism.The results show that:comprehensively considering the factors of economic and adsorption effect, we choose carbonizing at 600℃ for 1.5 h as the best modified protocol. Through orthogonal experiment and the single factor experiment, we get the following conclusions:the influence of different factors on Cr6+ of modified activated carbon are in the order of PH>adsorption time>addition amount. The best adsorption conditions of Cr6+ by modified activated carbon is:adsorbent addtion amount is 3 g, pH is 2, and adsorption time is 4 h. At the best condition, the adsorption efficiency of Cr6+ can reach 99%, and the residues of Cr6+ can meet" Drinking Water Health Standards" (GB5749-2012).Then we completed the adsorption kinetics and isothermal adsorption experiment, we found that the dynamic process of Cr6+ adsorption by modified activated carbon better conformed to the secondary dynamics model, which fitting degree (R2) was 0.9827. The adsorption isotherm using modified activated carbon conformed well to both the Langmuir model and Freundlich model.But the Langmuir model can better describe the adsorption process. The fitting results show that the adsorption isotherm is:Ce=2.87052+1.46357Ce... |
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