氨法制备球形氧化镁粉体及其应用研究

发布时间：2018-01-24 22:01

  本文关键词： 氢氧化镁 球形氧化镁 苯酚降解 臭氧氧化　出处：《北京化工大学》2015年硕士论文　论文类型：学位论文

【摘要】：本论文以氨水及硫酸镁为原料,研究纯度较高、单体分散性较好的球形氧化镁制备工艺。本文采用静态挥发实验,即在密闭容器中,通过氨水挥发的氨气与硫酸镁溶液经气液接触反应,制备出花球形氢氧化镁颗粒,然后对花球形氢氧化镁颗粒进行NaOH溶液洗涤,得到表面较为光滑且纯度较高的球形氢氧化镁,经过对球形氢氧化镁进行煅烧得到球形氧化镁颗粒。期间考察了各实验参数,如反应温度、反应时间、初始反应物浓度等,对花球形氢氧化镁产品微观形貌及结构的影响,研究了制备过程的工艺条件；经过对产品进行SEM、XRD、TG-DTG等测试及表征,并通过将晶体生长理论与氢氧化镁晶体结构相结合,对产物的生长机理做出了探讨。此外,还考察了煅烧温度对球形氧化镁粉体的柠檬酸活性值及形貌的影响,并将球形氧化镁应用于臭氧氧化处理苯酚废水实验,考察反应过程中球形氧化镁的作用。研究结果表明：以不同镁盐作为实验原料时,只有硫酸镁利于合成结构完整的球形氢氧化镁前驱体颗粒；室温条件下,当硫酸镁溶液浓度为0.5 mol/L,反应时间为24 h时,与挥发的氨气进行反应,能够得到球形完整、单体分散较好、粒径大小在7-8 um左右的球形氢氧化镁前驱体颗粒：将球形氢氧化镁前驱体进行4次洗涤,洗涤条件为：将球形氢氧化镁前驱体颗粒加入到30℃下浓度为0.2 mol/L的NaOH溶液中搅拌2 h,然后过滤干燥,可以得到纯度较高且表面较为光滑的球形氢氧化镁产品。对球形氢氧化镁产品在600℃下煅烧2 h,得到表面较为光滑、结构完整的球形氧化镁。在臭氧氧化降解苯酚实验中,分别将不同的碱性物加入到苯酚模拟废水溶液中搅拌1h后,通入臭氧进行氧化反应,反应结束时,添加球形氧化镁的苯酚溶液中的苯酚降解速率比添加适量NaOH要高13.1%,比轻烧镁高18.8%,比空白实验高33.7%,说明添加球形氧化镁对于臭氧氧化降解苯酚废水实验具有更强的促进作用。此外,添加球形氧化镁还有其他优点,例如不增加废水盐度,不会产生二次污染等。
[Abstract]:In this paper, ammonia water and magnesium sulfate were used as raw materials to study the preparation process of spherical magnesium oxide with high purity and good monomer dispersion. In this paper, static volatilization experiment was carried out, that is, in a closed vessel. The spherical magnesium hydroxide particles were prepared by the gas-liquid contact reaction between ammonia and magnesium sulfate solution, and then washed with NaOH solution. Spherical magnesium hydroxide with smooth surface and high purity was obtained. After calcination of spherical magnesium hydroxide, spherical magnesium hydroxide particles were obtained. The experimental parameters, such as reaction temperature and reaction time, were investigated. The effect of initial reactant concentration on the microstructure and morphology of spherical magnesium hydroxide was studied. The growth mechanism of the product was discussed by combining the crystal growth theory with the crystal structure of magnesium hydroxide. The effect of calcination temperature on citric acid activity and morphology of spherical magnesium oxide powder was also investigated, and spherical magnesium oxide was used in ozone oxidation treatment of phenol wastewater. The effect of spherical magnesium oxide in the reaction process was investigated. The results showed that when different magnesium salts were used as raw materials, only magnesium sulfate was beneficial to the synthesis of spherical magnesium hydroxide precursor particles with intact structure. At room temperature, when the concentration of magnesium sulfate solution is 0.5 mol / L and the reaction time is 24 h, the reaction with volatile ammonia can obtain spherical integrity and better dispersion of monomer. Spherical magnesium hydroxide precursor particles with particle size of 7-8 um: the spherical magnesium hydroxide precursor was washed for 4 times. The washing conditions were as follows: the spherical magnesium hydroxide precursor was added to the NaOH solution at 30 鈩，

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