粉末活性炭处理酚类突发性水污染的应用研究

以苯酚和多种氯酚(CPs)为代表的酚类是一类重要的有机污染物。针对饮用水突发性酚类污染物控制,考察了粉末活性炭(PAC)吸附工艺对苯酚及CPs的去除效果,并讨论了主要影响因素。结果表明,对CPs和苯酚的吸附反应可在10~60 min、300 min内完成,吸附速率从快到慢依次为TCP、MCP、DCP、PCP和苯酚。由于酚羟基(Ar—OH)电离作用受到影响,在3~11范围内去除率随pH值升高而降低。少量腐殖酸对吸附影响不大,但TOC质量浓度超过10 mg/L时腐殖酸可产生明显竞争吸附作用。热力学拟合表明,吸附反应符合Freundlich和Langmuir吸附等温式,苯酚/CPs在PAC上的吸附过程以物理吸附为主,且为放热反应,较低温度有利于吸附反应的进行。相比于准一级反应和孔内扩散反应,准二级动力学方程可较好地描述吸附过程。将PAC用于中山市某饮用水源的模拟突发性污染应急处理,投加10 mg/L的PAC即可有效去除原水中超过饮用水标准3~5倍的CPs类污染物,同时水处理成本仅有少量增加。

On the control of sudden water contamination by CPs-phenol with the powdered activated carbon

The present paper intends to introduce its study on how to control the unexpected water contamination by CPs-phenol with the powdered activated carbon phenols,including phenol and chlorophenols (CPs),a kind of important organic pollutant.To deal with the sudden water pollution or contamination caused by the phenols,we have developed such methods,as the advanced oxidation,bio-degradation and new adsorption materials.The above said methods we have developed have been founded for their convenience and reliability due to the characteristic advantages of the powdered activated carbon (PAC) recommended by the U.S.Environmental Protection Agency (EPA) for removing such organic pollutants from the water.For the above said purpose,we have made exploration of the adsorption characteristics and the main influential factors on PAC.The results of our study indicate that it is possible to finish the adsorption reactions of phenols to PAC from 10 min to 300 min,respectively.We have also found that the adsorption speed is also related with the content concentration of the chlorine substitution substance in an order from the top to bottom as TCP,MCP,DCP,PCP,and phenol.In addition,it is also possible for us to describe the adsorption process the Freundlich and Langmuir adsorption isotherms in an appropriate manner.For example,no evident effects can be found on the adsorption when there were small amounts of organic mixtures such as humic acid (HA).Nevertheless,if the concentration is over 10 mg/L,the HA would bring obvious competitive components and restrain its adsorption for CPs,for the reason that the effect of HA on the electroionization of the phenolic hydroxyl group (Ar—OH) due to the depression of the balance adsorption capacity when pH is added.However,if the ionization degree fails to keep its proportion to the adsorptions,the electrostatic adherence would fail to be the dominant factor affecting the adsorption of CPs.Therefore,the thermodynamic analysis tends to reveal that △H stands between-40-0 kJ/mol and the adsorption reaction can be attributed to the exothermic physical reactions,for which lower temperature turns to be favorable.As compared with the first-order reaction and pore-diffusion reaction,the nature of the adsorption tends to follow the second-order reaction model.