| The research on resin adsorption and desorption of industrial caffeine wastewater was discussed, and the conditions for adsorption and desorption were optimized.Several types of resins, with different properties, were used for industrial caffeine wastewater adsorption and desorption. XDA-8 resin, which had the maximum adsorption quantity and was easy to elute, was determined to be the adsorbent. Static adsorption and elution research of XDA-8 resin for pure caffeine showed that caffeine could be well adsorbed on XDA-8 resin, at pH6～7 which was the same to industrial caffeine wastewater. Langmuir equation, which was used for single layer adsorption, fit the process very well and the maximum theoretical quantity was 432.9 mg/g dry resin. Thermodynamic analysis showed that higher temperature lowered the adsorption quantity, and dynamic analysis showed that the adsorption process was controlled by liquid film diffusion at earlier stage while by particle inside diffusion at later stage. Desorption study showed that 60% ethanol was the best desorption agent, and the optimum elution temperature was 70 centigrade.Dynamic adsorption experiment was carried through with a column, which had a 10mm inner diameter and was filled with 25mL XDA-8 resin; industrial caffeine wastewater flowed passed this column. The experiment optimized the parameters of the process. When the wastewater passed by 2.0～3.0BV/h, the optimum adsorption speed, 150mL could be well adsorbed. More than 97% caffeine could be washed off the resin column by approximately 80mL 60% ethanol, at 70 centigrade.After adsorption and desorption, the resin column must be regenerated. Dynamic study showed the resin column could be well simply regenerated by 6BV caffeine wastewater, which was previously adsorbed by the resin, with the flow speed 3BV/h. When the resin was continuously regenerated for 5 times, it must be intense regenerated by strong acid and strong alkali. |
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