混合脂肪酸钠辅助制备硫酸钙晶须

硫酸钙晶须应用范围广、综合性能优异、性价比高，具有良好的应用前景。以氯化钙为主要原料，添加油酸钠、硬脂酸钠以及油酸钠与硬脂酸钠的混合物作为改性剂，采用常压酸化法制备了长径比高、疏水性能好的硫酸钙晶须。探究了氯化钙浓度、反应时间、反应温度、油酸钠和硬脂酸钠及其混合物的用量等因素对制备的硫酸钙晶须长径比及疏水性的影响，确定了最佳制备条件。采用扫描电镜（SEM）、接触角测量仪、X射线衍射仪（XRD）、红外光谱（FT-IR）及Zeta电位分析等对产品进行了表征。通过实验得到制备硫酸钙晶须的最佳工艺条件：氯化钙溶液质量浓度为0.11 g/mL时，添加与氯化钙等物质的量的浓硫酸4.8 mL，加入4%油酸钠和6%硬脂酸钠混合物（以质量分数计）作为改性剂，在140 ℃油浴锅中加热搅拌1 h。在此工艺条件下，制备的硫酸钙晶须长径比为32~106，接触角可达120.2°。XRD结果表明，所得硫酸钙晶须为半水硫酸钙晶须和二水硫酸钙晶须的混合物。红外光谱和Zeta电位分析表明，油酸钠和硬脂酸钠以化学吸附的形式吸附在晶须表面。当加入油酸钠和硬脂酸钠混合物时，油酸钠和硬脂酸钠共吸附于晶须表面，使得晶须表面吸附的脂肪酸更多，晶须疏水性更强。

Preparation of calcium sulfate whiskers assisted by mixed sodium fatty acid

Calcium sulfate whiskers have merit of wide range of applications，excellent comprehensive performance and cost?effective，resulting in good application prospects.Calcium chloride was used as the main raw material，sodium oleate，sodium stearate，and a mixture of sodium oleate and sodium stearate were used as crystal growth promoters.The normal pressure acidification method was used to prepare whiskers of high aspect ratio and good hydrophobicity.The influence of calcium chloride concentration，reaction time，reaction temperature，the amount of sodium oleate，sodium stearate and their mixture on aspect ratio and hydrophobicity of calcium sulfate whisker was studied，and the optimal preparation conditions were determined.The products were characterized by scanning electron microscopy（SEM），contact angle measuring instrument，X-ray diffraction（XRD），infrared spectroscopy（FT-IR），and Zeta potential analysis.The optimal conditions for the preparation of calcium sulfate whiskers were listed as follows：mass concentration of calcium chloride solution of 0.11 g/mL，adding 4.8 mL of concentrated sulfuric acid in the amount of calcium chloride，adding the mixture of 4% sodium oleate and 6% sodium stearate（calculated by mass fraction） as modifier，stirring in oil bath at 140 ℃ for 1 h.Under this optimal conditions，the aspect ratio of prepared calcium sulfate whiskers was ranged from 32 to 106，and the contact angle reached 120.2°.XRD results showed that the obtained calcium sulfate whiskers were a mixture of hemihydrate calcium sulfate whiskers and dihydrate calcium sulfate whiskers.Infrared spectroscopy and Zeta potential analysis showed that sodium oleate and sodium stearate were adsorbed onto the surface of whiskers in the form of chemical adsorption.When the mixture of sodium oleate and sodium stearate was added，sodium oleate and sodium stearate were co?adsorbed on the whiskers surface，which made the surface of whisker adsorb more fatty acids and the hydrophobicity of whisker stronger.