ZnFe~Ⅲ类水滑石制备过程研究

以ZnSO4、FeSO4为原料,采用共沉淀和氧化的两步法合成了ZnFeⅢ二元类水滑石化合物,详细探讨了原料配比、pH及氧化处理条件等因素对合成产物物相的影响,借助XRD,FTIR,N2吸附等手段对合成物物化性能进行表征。研究结果表明:以Zn(NO3)2、Fe(NO3)3为原料,改变合成条件只能得到碱式碳酸锌或碱式硝酸锌;而以FeSO4、FeSO4为原料,采用共沉淀和氧化的两步法可得到晶相单一、结晶度良好的ZnFeⅢHTLcs。两步法制备ZnFeⅢ类水滑石的最适宜的条件为:n(Zn2+)/n(Fe2+)=2.0～3.0,pH=6.0～7.0,氧化温度为25℃,该条件下合成的ZnFeⅢHTLcs有较高的热稳定性,热分解温度为600℃;有较窄的粒径分布,中值粒径为1.24μm,平均粒径为1.28μm;吸附等温线类型为Ⅱ型,比表面积为23.08m2/g。

Research on the Preparation Process of ZnFe~Ⅲ HTLcs

ZnFeⅢ-hydrotalcite-like-compounds(ZnFeⅢHTLcs) were synthesized from ZnSO4 and FeSO4by two-step method,i.e.co-precipitation and subsequent oxidation by H2O2.The influence of the parameters such as ratio of materials,pH value and the oxidation condition,was discussed.Characterization of samples was carried out by XRD,FTIR,and N2-adsorption.The results show that basic zinc carbonate or alkaline zinc nitrate was obtained from Zn(NO3)2 and Fe(NO3)3 by changing the synthesis conditions.However,a single crystalline phase ZnFeⅢHTLcs with high crystallinity was obtained from ZnSO4 and FeSO4 by the two-step method.The optimized condition for the preparation of ZnFeⅢHTLcs by two-step method was,n(Zn2+)/n(Fe2+)=2.0~3.0,pH=6.0~7.0,and the oxidation temperature 25℃.The prepared ZnFeIIIHTLcs showed excellent thermal stability and narrow particle size distribution.The thermal decomposition temperature was 600℃.Median particle size was 1.24 μm and average particle size was 1.28 μm.The adsorption isotherms of the ZnFeⅢHTLcs belonged to Ⅱ-type and the specific surface area was 23.08 m2/g.