酸性条件下壳聚糖改性粉煤灰的制备及其对水中Cr(VI)的吸附机理

Preparation of chitosan modified fly ash under acid condition and its adsorption mechanism for Cr(VI)in water

以壳聚糖和粉煤灰为原料,经乙酸和硫酸交联改性,采用酸浸-包覆法制备壳聚糖包覆粉煤灰(CWF)。利用扫描电子显微镜(SEM)和X射线衍射(XRD)测试了CWF的微观结构,通过吸附实验研究了CWF对水中Cr(VI)的去除效果,结合吸附模型、扩散模型和动力学模型探讨了吸附机理。结果表明:实验制备的复合材料具有孔隙结构,并在粉煤灰表面形成类似SiO_(2)和壳聚糖链状涂层的晶体结构;新型改性材料具有较大的表面粗糙度、比表面积和更多的吸附通道;改性材料通过CrO_(4)^(2−)、CrO_(7)^(2−)和-NH_(3)^(+)基团之间的静电吸引以及表面酸官能团的多组分吸附功能吸附Cr(VI);Cr(VI)在溶液中的运动是液相主体向液膜表面扩散的过程。

Chitosan-coated fly ash(CWF)was prepared by the acid leaching-coating method.Chitosan and fly ash were crosslinked in the solution of acetic acid and sulfuric acid.The microstructure of CWF was conducted by scanning electron microscope(SEM)and X-ray diffraction(XRD).The removal of Cr(VI)from water by CWF was studied by adsorption experiments.The composite prepared by the experiment developed a pore structure and a crystal structure similar to SiO_(2) and chitosan chain-like coating was formed on the surface of fly ash.The new modified material has larger surface roughness,specific surface area and more adsorption channels.The Cr(VI)was enriched in modified materials by electrostatic adsorption between CrO_(4)^(2−)、CrO_(7)^(2−)and-NH_(3)^(+) group and surface acid functional groups.The movement of Cr(VI)in solution is a diffusion process from the main body of the liquid phase to the surface of the liquid film.