以天然菱镁矿为原料，采用尿素法制备纳米Mg-Al水滑石。考察了煅烧时间和温度对菱镁矿分解率的影响。结果表明，最佳条件为700℃下煅烧0.5 h。另外考察了尿素用量对水滑石形貌、尺寸、结晶度的影响，还有不同n( Mg)∶ n ( Al )对水滑石纯度的影响。用 XRD、SEM 对产物进行分析。 XRD 分析结果表明，当溶液中n(尿素)∶n(NO3-)=3∶1时，合成的水滑石样品具有较高的结晶度；n(Mg)∶n(Al)=2∶1时，合成的水滑石纯度可达到100%；随着尿素用量的增多，合成样品的粒径逐渐增大。 SEM分析结果表明，用菱镁矿合成的样品层比用硝酸镁试剂合成的样品层厚很多。%Natural magnesite were used as raw material to synthesis nanosized Mg-Al hydrotalcite by a u-rea homogeneous precipitation method. The effect of calcining time and temperature on the decomposition rate of magnesite was studied. The results show that the optimum conditions of calcination was 700 ℃ for 0. 5 h. In addition,the effect of the urea amount on hydrotalcite crystal size,appearance and crystallinity, and the effect of different Mg/Al molar ratio on purity. The hydrotalcite products were characterized by means of XRD and SEM. XRD analysis showed that when n(urea)∶n(NO3 -) was 3,the hydrotalcite had high crystallinity;and when n(Mg)∶n(Al) was 2,the purity can reach 100%;with the increase of urea amount,the particle size increased. SEM analysis showed that the crystal layer of the samples prepared from magnesite were much thicker than the samples prepared from magnesium nitrate.
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