磁性壳聚糖/氧化石墨烯吸附材料的制备及其对Pb(II)的吸附

以壳聚糖(CS)和改进的hummers法制备的氧化石墨烯(GO)为原料,采用化学交联法合成出CS-GO复合材料,再通过化学共沉淀法制备出磁性壳聚糖/氧化石墨烯(MCSGO)复合吸附材料。采用X射线衍射仪(XRD)和傅里叶变换红外光谱仪(FT-IR)对MCSGO的结构和官能团进行表征,并研究了MCSGO吸附水体中Pb(II)的吸附性能和吸附机理。结果表明,GO和CS以NH-CO键交联,通过负载Fe₃O₄成功赋予CS-GO磁性;室温下,当Pb(II)初始质量浓度为50mg/L、吸附剂用量为0.04g、pH值为5时,吸附90min达平衡,平衡吸附量为60.99mg/g,拟二级动力学模型和Langmuir等温吸附模型可以用来描述MCSGO对Pb(II)的吸附行为,说明该吸附过程属于均匀表面的单分子层化学吸附。在外加磁场下对MCSGO进行磁分离,表明MCSGO具有很好的磁分离性能。以盐酸作为解吸剂对MCSGO进行再生,MCSGO吸附材料循环再生使用6次后,吸附量仅下降16.72%,说明MCSGO具有优异的循环再生吸附性。

Preparation of magnetic chitosan/graphene oxide composites and its adsorption performance to Pb(II)

The chitosan (CS) and graphene oxide (GO) synthesized with the modified hummers method were used as raw material to prepare CS-GO composites by chemical crosslinking. Then the magnetic chitosan/graphene oxide (MCSGO) composite absorbent material was prepared by chemical co-precipitation method. The structure and functional groups of MCSGO were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The adsorption property and adsorption mechanism of Pb(II) in water on MCSGO were studied. The results showed that CS was cross-linked with GO via NH-CO bond. The CS-GO was successfully endowed magnetic property by loading Fe₃O₄. The adsorption equilibrium could be reached at room temperature within 90 min under the following conditions: the initial mass concentration of Pb(II) was 50mg/L, the dosage of adsorbent was 0.04g and the pH was 5. The equilibrium adsorption capacity was 60.99mg/g. The adsorption behavior of Pb(II) on MCSGO could be described using pseudo-second-order kinetics model and Langmuir isotherm model. It indicated that this adsorption process was the chemical monolayer adsorption of homogeneous surface. The experimental results of magnetic separation under external magnetic field showed that MCSGO had good magnetic recyclability. Hydrochloric acid was used as desorption reagent for the regeneration of MCSGO. The adsorption capacity of Pb(II) on MCSGO only decreased by 16.72% after recycling for six times, indicating the MCSGO had excellent performance of regeneration.