磁性多壁碳纳米管吸附亚甲基蓝和铜(Ⅱ)

Adsorption of Methylene Blue and Cu(Ⅱ) by synthesized magnetic multi-walled carbon nanotubes

针对实际废水中有机物和重金属离子往往同时存在,吸附处理后吸附剂难分离2个问题,采用化学共沉淀的方法制备了磁性多壁碳纳米管(MMWCNT),研究了亚甲基蓝(MB)和铜(Ⅱ)在MMWCNT上的单一和竞争吸附。考察了一元体系中吸附动力学、吸附热力学及p H值对吸附性能的影响。探究了吸附剂的循环利用能力、回收率以及二元体系中MB和Cu(Ⅱ)之间的竞争吸附现象。结果表明,一元体系中,在4 h时内对MB和Cu(II)的吸附达到平衡,吸附过程符合准二级动力学模型,等温吸附数据符合Langmuir模型,最大吸附量分别为46.03 mg·g-1和27.74 mg·g-1。p H值是影响吸附效果的重要因素。5次解吸循环实验后,MMWCNT吸附性能仍然良好,表明MMWCNT有望运用于实际水处理中。竞争吸附过程中MB优先吸附,当MB吸附平衡后,随着吸附剂量的增加,Cu(Ⅱ)的吸附效率从11%增到73%。

Organic matter and heavy metals often coexist in wastewater, and the co-pollutants are usually removed with an adsorption process. However, the conventional adsorbents suffer from inconvenient separation methods following wastewater treatment. In this study, magnetic multi-walled carbon nanotubes （MMWCNT） were synthesized by a chemical co-precipitation method, and were used as adsorbents for the adsorption of meth- ylene （MB） and Cu（ Ⅱ ） in both single and binary systems. Adsorption kinetics, isotherms, and the effects of pH on the adsorption were also discussed. Furthermore, an intensive study was conducted to investigate the reus- ability and recovery of MMWCNT adsorbents, and the competitive adsorption between MB and Cu（Ⅱ）. Results indicated that 4 h was required to reach equilibrium for both the MB and Cu （ Ⅱ ） adsorbed onto MMWCNTs, and that the sorption processes coincided with a pseudo-second-order kinetic model. The sorption isotherm was fitted with a Langmuir model, and the maximum adsorption was 46.03 mg· g-1 and 27.74 mg · g-1 for MB and Cu（ Ⅱ ） , respectively. The pH value played an important role in the adsorption efficiency. The adsorption be- havior of MMWCNT remained after five desorption cycles, and this indicated that MMWCNT had potential appli- cation in wastewater treatment. Compared with Cu （Ⅲ） , MB favored adsorption onto MMWCNT in competitive adsorption process. Upon reaching the adsorption equilibrium for MB, the adsorption efficiency of Cu（Ⅱ ） in- creased from 11% to 73% with the increase of MMWCNT dosage.