改性褐煤吸附酸性矿山废水中Cu^(2+)、Zn^(2+)的试验研究

Experimental study on adsorption of Cu^(2+) and Zn^(2+) in acid mine wastewater by modified lignite

针对酸性矿山废水(Acid Mine Drainage,AMD)中的Cu^(2+)、Zn^(2+)含量高,褐煤吸附能力有限等问题,以褐煤为原材料,采用球红假单胞菌对褐煤进行改性制备微生物改性褐煤,探究褐煤和微生物改性褐煤对AMD中Cu^(2+)、Zn^(2+)的吸附特性和吸附稳定性。同时,利用SEM、BET和FTIR等手段,揭示褐煤、微生物改性褐煤对Cu^(2+)、Zn^(2+)的吸附机理。结果表明,与褐煤相比,微生物改性褐煤对Cu^(2+)、Zn^(2+)的吸附去除率均提高15%以上;且微生物改性褐煤对Cu^(2+)、Zn^(2+)的吸附饱和容量分别为22.625 mg/g和21.825 mg/g,较原褐煤分别提高了20.66%和19.92%;脱附试验表明,褐煤及改性褐煤对金属离子的吸附具有较高的稳定性。褐煤、微生物改性褐煤对Cu^(2+)和Zn^(2+)的吸附均符合准二级动力学模型,说明吸附过程为化学吸附,主要为离子交换作用;褐煤、微生物改性褐煤吸附Cu^(2+)、Zn^(2+)两种金属离子的等温线均属于Langmuir模型,吸附符合单分子层吸附过程。由SEM、BET和FTIR测试可知,褐煤经球红假单胞菌改性后表面结构遭到破坏,比表面积大幅增加,部分官能团溶解导致褐煤表面孔隙增加;同时,褐煤分子结构发生改变,含有C=0的烯烃及环状烃中的主链、支链断裂、褐煤中—CHO和C=0等含氧官能团会出现分解,从而产生较小的羟基类和醇基类等小分子有机物,—OH、—COOH等含氧官能团大量增加,吸附点位增多,提高了褐煤的吸附能力。

In view of the problems of high content of Cu^(2+) and Zn^(2+) in acid mine drainage(AMD),and limited adsorption capacity of lignite,the lignite was used as raw material and pseudomonas aeruginosa was used to modify lignite to prepare microbial modified lignite,so as to explore the adsorption characteristics and adsorption stability of Cu^(2+) and Zn^(2+) in AMD.At the same time,the adsorption mechanism of Cu^(2+) and Zn^(2+) on lignite and microbially modified lignite was revealed by means of SEM,BET and FTIR.The results show that compared with lignite,the adsorption and removal rates of Cu^(2+) and Zn^(2+) by microbial modified lignite were all increased by more than 15%,and the adsorption saturation capacity of microbially modified lignite for Cu^(2+) and Zn^(2+) is 22.625 mg/g and 21.825 mg/g,respectively,which were 20.66% and 19.92% higher than that of the original lignite,and the desorption test shows that lignite and modified lignite have high stability in adsorption of metal ions.The adsorption of Cu^(2+) and Zn^(2+) by lignite and microbially modified lignite conform to the pseudo-second-order kinetic model,,indicating that the adsorption process is chemical adsorption and mainly ion exchange.The isothermal adsorption line fitting of adsorption Cu^(2+) and Zn^(2+) by lignite and modified lignite is more in line with the Langmuir model,and the adsorption conforms to the single-molecule layer adsorption process.From SEM,BET and FTIR tests,it can be seen that the surface structure of lignite modified by Pseudomonas aeruginosa is destroyed,the specific surface area is greatly increased,and some functional groups are dissolved,which leads to the increase of surface pores of lignite.At the same time,the molecular structure of lignite changes,the main chain and branch chains in olefins containing ■ and cyclic hydrocarbons are fractured,and oxygen-containing functional groups such as—CHO and ■ in lignite will decompose,resulting in the production of smaller hydroxyl groups.And the small molecular organics such as alcohol bases,and oxygen-containing functional groups such as —OH and —COOH are greatly increased,the adsorption sites are increased,and the adsorption capacity of lignite is improved.