ZIF-8低温碳化改性及其吸附性能研究

Study of low-temperature carbonization modification of ZIF-8 and its adsorption performance

高浓度、高排放和高毒性的有机染料废水对水体环境和人体危害极大,开发具有高吸附量、优良循环利用性和选择性吸附的新型吸附剂十分重要。锌有机框架材料ZIF-8具有高比表面积、优良稳定性、低成本和丰富活性位点,可针对有机染料进行有效吸附。本文对ZIF-8进行低温碳化处理,通过X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)、热重(TG)和Zeta电位等表征其结构变化。结果表明550℃碳化处理后的材料(CZ-550)具有高吸附酸位点、高比表面积和表面正电荷(+24 mV)以及较高吡啶N含量。在较宽pH范围(pH=3-13)内对甲基橙具有高吸附性能,最大饱和吸附量为1100 mg·L^(-1),具有对阴离子型有机染料的选择性吸附。吸附动力学研究表明其符合伪二级动力学模型,与Langmuir、Freundlich和Temkin三种等温吸附模型具有较好相关性,吸附机理为物理和化学吸附。因而低温碳化处理的CZ-550在阴离子吸附领域具有良好的应用前景。

Organic dye wastewater with high concentration,high discharge and high toxicity posed harm to the water environment and human health.It was important to develop new adsorbents with high adsorption capacity,excellent recycling ability,and selective ad-sorption materials.Zinc organic framework material ZIF-8 have high specific surface area,excellent stability,low cost and rich active site,which can effectively adsorb organic dyes.This article conducted low-temperature carbonization treatment on ZI F-8,and char-acterized its changes of structure through X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),X-ray photoe-lectron spectroscopy(XPS),thermogravimetry(TG),and Zeta potential.The results indicated that the sample(CZ-550),which was carbonization treatment at 550℃,had highadsorption acid sites,highspecific surfacearea,positivesurfacecharge(+24mV),and high pyridine N content.It had high adsorption performance for methyl orange over a wide range of pH(pH=3-13),with a maximum saturated adsorption capacity of 100 mg·L^(-1),and selective adsorption for anionic organic dyes.The study of adsorption kinetics showed that it conformed to the pseudo second-order kinetic model and had good correlation with Langmuir,Freundlich,and Temkin isothermal adsorption models.The adsorption mechanisms were physical and chemical adsorption.Therefore,CZ-550 treated with low-temperature carbonization had good application prospects in the field of anion adsorption.