新型树脂对氯酚类物质的吸附研究

Adsorption of chlorophenols on acetyl modified hypercrosslinked resins

合成了乙酰氯修饰树脂NDA-O,与Purolite公司的MN-200相比,合成的树脂比表面积较小,但酸性官能团较多。用两种树脂吸附2-氯酚、4-氯酚和2,4-二氯酚发现,吸附结果可以用Langmuir和Freundlich等温吸附方程很好地模拟,合成的NDA-O对3种氯酚类物质的吸附能力优于MN-200。两种树脂对氯酚类物质的吸附量随着温度的升高而减少,表明吸附是放热过程,同时对氯酚类物质的吸附焓变随着吸附量的增大而减小。对同一种树脂来说,吸附量随着氯代程度的增加而增加,取代氯数相同的时候,吸附量与吸附质的Kow成正相关。进一步研究了pH对吸附的影响,在pH大于9时,3种氯酚类物质的吸附量均急剧减少。

A novel acetyl modified hypercrosslinked resin （NDA-O） was synthesized. Its adsorptive capacities for 2-chlorophenol,4-chlorophenol and 2,4-dichlorophenol were determined and compared with those of a commercial resin. Although the popular Purolite MN-200 had a larger specific surface area and a greater micropore volume, NDA-O exhibited higher capacities because of its higher acid exchange capacity or more polar oxygenated functional groups on the surface. The adsorption isotherm data were well represented by both the Langmuir model and the Freundlich model. The adsorption capacities decreased with increasing the temperature within the range of 25 - 55 ℃, they were lower at a more basic pH as chlorophenols were mostly in anionic forms which were far less well adsorbed on the negatively charged adsorbent surface.