氨基酸接枝和二氧化硅包覆纳米碳酸钙的合成研究

发布时间：2018-02-17 01:44

  本文关键词： 纳米CaCO_3 表面改性 氨基酸 活化度 耐酸性 CaCO_3/SiO_2复合物　出处：《南昌大学》2015年硕士论文　论文类型：学位论文

【摘要】：纳米碳酸钙(CaCO3)是一种应用广泛的无机填料,但由于粒度小、表面能高、亲水性强、耐酸性差等缺陷,在应用过程中必须对其进行表面改性。本实验选取氨基酸和二氧化硅对纳米CaCO3进行改性研究,制备改性纳米CaCO3,对反应过程中的条件进行了探索和优化。通过在纳米CaCO3浆液中加入氨基酸,在纳米CaCO3表面引入羧基、氨基等活性基团实现表面改性,并用FTIR. XRD和TGA等手段对改性机理进行研究。结果表明,L-赖氨酸、谷氨酸是以化学键合的形式接枝到纳米CaCO3表面；谷氨酸改性优于L-赖氨酸；改性前后没有出现新的衍射峰；氨基酸改性后纳米CaCO3的衍射峰强度明显降低,且谷氨酸改性样的衍射峰强度低于L-赖氨酸改性样强度。碳化法制得纳米CaCO3,CaCO3平均粒径55nm左右,方解石结构,晶型结构较好,结晶度较高。L-赖氨酸接枝纳米CaCO3最佳工艺条件为：超声分散1h,水为改性溶剂,CaCO3料浆浓度8～10wt%,L-赖氨酸用量m(L-赖氨酸)：m(纳米CaCO3)=10wt%,改性温度70℃,改性时间70min,搅拌速率80Orad/min。在此优化工艺条件下,改性纳米CaCO3的活化度46.9%,吸油值42.37g/100g。谷氨酸改性纳米CaCO3最佳工艺条件为：CaCO3料浆浓度10wt%,m(谷氨酸)/m(CaCO3)=10wt%,改性温度90℃,改性时间100min。优化条件下,改性纳米CaCO3的活化度86.07%,吸油值23.64g/100g。以氨水、纳米CaCO3和磷肥工业副产物氟硅酸为原料,制备了CaCO3/SiO2复合物。实验确定了SiO2包覆CaCO3的适宜条件：反应温度60℃,配料比m(SiO2)/m(CaCO3)=8wt%,反应终点pH值9.0,陈化时间8h以上,优化条件下,浸泡CaCO3/SiO2复合物24h的缓冲溶液c(Ca2+)=0.014mol/L,耐酸性能好,包覆后纳米CaCO3的耐酸性能明显提高。对适宜条件下的包覆产品进行FTIR、XRD和粒度分析,结果表明：SiO2与CaCO3发生了化学键合作用,SiO2以无定型态包覆于纳米CaCO3表面,包覆后纳米CaCO3粒径变小,平均粒径44.67nm。
[Abstract]:Nano calcium carbonate (CaCO3) is a widely used inorganic filler, but due to its small particle size, high surface energy, strong hydrophilicity, poor acid resistance, etc. In this experiment, amino acid and silica were selected to modify the surface of CaCO3. The modified nano-CaCO _ 3 was prepared, and the reaction conditions were explored and optimized. The surface modification was realized by adding amino acids to the nano-CaCO _ 3 slurry, introducing carboxyl groups, amino groups and other active groups on the surface of nano-CaCO _ 3. The modification mechanism was studied by FTIR. XRD and TGA. The results showed that L- lysine and glutamic acid were grafted to the surface of nano-#en2# in the form of chemical bonding, the modification of glutamate was superior to that of L- lysine, and there were no new diffraction peaks before and after modification. The diffraction peak intensity of CaCO3 modified by amino acid was obviously decreased, and the diffraction peak intensity of glutamic acid modified sample was lower than that of L- lysine modified sample. The average diameter of nano-CaCO3 / CaCO3 was about 55 nm, and the calcite structure and crystal structure were better than that of L- Lysine modified sample. The optimum technological conditions of high crystallinity. L- lysine grafted nanocrystalline CaCO3 were as follows: ultrasonic dispersion for 1 hour, water as the modified solvent for 8 ~ 10 wts, L- L- lysine dosage ML-L- 1: M (nano-CaCO3 + 10wt), modification temperature 70 鈩，

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