PVP与表面活性剂混合模板对CaCO3结晶的调控作用

聚乙烯吡咯烷酮(PVP)分别与十六烷基三甲基溴化铵(CTAB)、十二烷基硫酸钠(SDS)组成混合模板,在CaCl2、Na2CO3体系中调控合成CaCO3晶体,考察结晶温度对CaCO3晶体的影响。采用电导率法确定混合模板中表面活性剂的使用浓度。通过扫描电镜(SEM)、傅里叶变换红外光谱仪(FT-IR)及X线衍射仪(XRD)对晶体的形貌和结构进行表征。结果表明:SDS与CTAB结合到PVP长链上的浓度分别为2.4和1.1 mmol/L。在PVP-CTAB模板中,5℃时为方解石的层状CaCO3聚集体,25℃时有部分球形球霰石出现,90℃时得到了棒状文石晶体。在PVP-SDS模板中,5和25℃时均为方解石型球状CaCO3聚集体,90℃时得到棒状文石晶体。

Crystallization of CaCO3 induced by mixed template of PVP and surfactant

Calcium carbonate was prepared by the Na2CO3 with CaCl2 in polyvinylpyrrolidone(PVP) and surfactants(hexadecyl trimethyl ammonium bromide(CATB) or sodium dodecyl sulfate(SDS)) at different temperatures.The interaction between the polymer and surfactants was confirmed by the method of conductivity.The products were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR) and X-ray diffraction(XRD).Results showed that the plot of SDS binded to the long chain of PVP was 2.4 mmol/L and the CTAB was 1.1 mmol/L.In the PVP-CTAB system,the precipitations were layered aggregates of calcite at 5 ℃,and at 25 ℃ the spherical vaterite could be prepared,while at high temperature of 90 ℃,rod-like aragonite crystals were obtained.In the PVP-SDS system,the spherical aggregates of calcium carbonate could be prepared at 5 and 25 ℃ while rod-like aragonite crystals were obtained at 90 ℃.