褐煤对苯酚的吸附性能及机制研究

酚类废水是一种有毒且排放量较大的有机废水,排放之前必须进行有效处理。以污染物苯酚为研究对象,褐煤为吸附剂,基于实验室小试,在正交试验的指导下,采用振荡平衡法研究了褐煤对苯酚的吸附效果,确定了褐煤用量、振荡吸附时间、温度、pH值对苯酚模拟废水吸附效果的影响。结果表明:在褐煤用量为10 g、振荡时间为1.5 h、温度为25℃、pH值为6的条件下,对100 mL质量浓度为100 mg/L的苯酚模拟废水处理效果最佳,苯酚的去除率可达70.86%。在最佳吸附条件下,一方面结合吸附苯酚前后褐煤比表面积及孔隙结构的变化进行分析,另一方面利用FT-IR对褐煤吸附苯酚前后表面官能团的变化进行了对比分析。褐煤内部孔隙发达,存在多类孔,以50 A以下的孔居多数,表明其微孔结构较复杂,且吸附行为致使孔隙面积缩小至近1/3,微孔减少明显,表明微孔对吸附过程影响很大;褐煤表面含有丰富的含氧官能团,为吸附苯酚提供了条件,在吸附苯酚的过程中物理吸附与化学吸附同时存在,褐煤主要表面宫能团—COOH、酚羟基及苯环结构骨架在化学吸附苯酚方面发挥着重要作用。这两方面从微观角度很好地解释了褐煤的吸附机理。

Adsorptive inclination of lignite and its mechanism for phenol adsorption

In this paper,we have managed to conduct a series of orthogonal experiments in hoping to make assessment over the adsorption feature of phenol from the phenol simulated sewage with lignite through oscillation balance.As is known,it is necessary for the organic sewage with phenol compounds to be treated by a series of efficient treating procedure due to their enormous emission and being highly toxic.It is just for this purpose that we have also made an investigation of the effect of lignite dosage,oscillation time,temperature as well as the pH value necessary for the mimic phenol solutions for phenol removing.The results of our investigation and experiments show that the optimal conditions for treating the 100 mL simulative phenol sewage at a concentration of 100 mg/L should be set up as follows:10 g of lignite,1.5 hours of oscillation time,at the temperature of 25 ℃ with pH value being 6.Under the optimal adsorption conditions,it would be possible for the removal rate of phenol to be as high as 70.86％.Under the optimized condition,the pore structure of lignite can be analyzed with the low-temperature nitrogen adsorption method,which is characteristic of the change of pore size distribution,pore volume and specific areas pre-&-post lignite adsorption of phenol.The results of our experiments demonstrate that there remains rich inner pore structure and multiple categories of pore in lignite.Moreover,it can be seen that the main size distribution of the lignite pore before and after the adsorption can still be kept below 50 (A).On the other hand,the adsorptive behavior that results from the pore size reduction tends to be left about one-third with micro pores,indicating that the micro porous structure proves to be affected by the adsorption process.On the other hand,an analysis of the change of lignite surface functional groups with FT-IR spectra may help to reveal that there may still exist rich oxygenic functional groups in the surface of lignite,which allows for the adsorption of phenol.Further comparison of the spectra pre-&-post the adsorption can help us to find that there may coexist the physical adsorption and chemisorptions in the lignite adsorption process of phenol,in which the main surface of the functional groups,that is,the —COOH,phenolic hydroxyl vibration absorption groups and the benzene skeleton characteristic peak may still play an important role in the chemical adsorption.