MMA体系注凝成型低成本制备氧化铝陶瓷膜及其分离特性研究

发布时间：2018-10-25 10:44

【摘要】：膜分离技术主要包括微滤、超滤、纳滤和反渗透等方法,由于其具有分离效率高、操作方便、能耗低、工作环境安全、无污染等诸多优点,在食品、医药、冶金、能源、化工、环保等领域有着十分广泛的应用。根据膜制备材料的不同,可将其分为两大类:有机膜和无机膜。无机膜以陶瓷膜为主导,具有耐高温、耐酸碱、使用寿命长等优点,拥有十分广阔的发展前景。目前,商品化的陶瓷膜一般为非对称形式,在制备过程中需要进行多次的烧结和涂膜,不仅过程繁琐,而且消耗大量的能源,导致陶瓷膜制备成本居高不下。对于这种状况,本文以两种不同的成型工艺制备支撑体和分离层,进行一次性共烧结得到陶瓷膜。为探究其分离能力,用染料进行过滤性能测试,最后采用有机无机复合膜提高对染料的去除率。针对支撑体烧结温度过高的问题,对其进行低温烧结的研究。向骨料中加入复合助烧剂(NaSiO3+TiO2+CaCO3+MgO)降低支撑体的烧结温度。探讨了Na Si O3的加入量对支撑体各性能的影响,发现NaSiO3的添加对支撑体低温烧结由明显的促进作用,但加入量需要控制得当。通过正交实验确定nasio3含量,成孔剂含量、粘结剂含量和保温时间的最优方案为4%、6%、0.6%和2h。在此最优条件下,重点研究温度的影响,在较低的温度区间1400-1450℃得到的陶瓷膜各性能较优,适宜作为更精密的分离层载体使用。对传统注凝成型工艺进行改进,以mma作为有机单体,通过本体聚合后得到预聚液与粉体骨料混合制成涂膜液,涂覆在支撑体生坯上干燥后形成凝胶层,随后进行共烧结得到非对称陶瓷膜。实验结果表明:当引发剂用量为0.1%,于90℃水浴中加热11.5min,得到的预聚液粘度为350mpa?s左右,流动性良好。可与氧化铝粉体混合作为涂膜液使用。涂膜液中粉体粒径越小、浆料固相体积分数越大,烧结温度越高,得到的陶瓷膜纯水通量、孔隙率和孔径越小。为了得到孔径小,且分布更均匀的陶瓷膜,选择平均粒径为4.49μm的原料,控制浆料固相体积分数和烧结温度为50%和1420℃。通过对两种不同染料进行过滤后发现,mma注凝成型制得的陶瓷膜比传统注浆成型制得支撑体过滤性能更好,说明mma体系注凝成型工艺在分离层制备方向具备一定的应用价值。为了进一步强化膜过滤性能,选择以低成本的有机膜负载于陶瓷膜上,通过相转化制得有机/无机复合膜。探究聚醚砜浓度、浸渍时间、浸渍温度和凝固浴温度对复合膜性能的影响。结果表明聚醚砜浓度和浸渍温度越高,复合膜纯水通量越低,对直接染料去除率越高。凝固浴温度越高,水通量越高,对直接染料去除率降低。浸渍时间则几乎没有影响。通过控制变量法在聚醚砜浓度为15%,浸渍时间为1h,浸渍温度为40℃、凝固浴温度为20℃时,得到的复合膜性能最佳,此时膜纯水通量为416.8 L?m-2?h-1,对直接染料去除率可以达到94.12%。
[Abstract]:Membrane separation technology mainly includes microfiltration, ultrafiltration, nanofiltration and reverse osmosis. Because of its advantages of high separation efficiency, convenient operation, low energy consumption, safe working environment, no pollution and so on, it is widely used in food, medicine, metallurgy, energy, chemical industry, etc. Environmental protection and other fields have a very wide range of applications. According to the different preparation materials, the membrane can be divided into two categories: organic membrane and inorganic membrane. Inorganic membrane, which is dominated by ceramic membrane, has the advantages of high temperature resistance, acid and alkali resistance and long service life. At present, the commoditized ceramic membrane is usually in the form of asymmetric, and it is necessary to sintering and coating many times in the process of preparation, which is not only cumbersome but also consumes a lot of energy, which leads to the high cost of ceramic membrane preparation. In this paper, support and separation layer were prepared by two different molding processes, and ceramic membranes were prepared by one-time co-sintering. In order to study its separation ability, the filtration performance was tested with dyes, and the removal rate of dyes was improved by organic inorganic composite membrane. Aiming at the problem of high sintering temperature of the support, the low temperature sintering of the support was studied. The sintering temperature of the support was reduced by adding a composite sintering aid (NaSiO3 TiO2 CaCO3 MgO) to the aggregate. The effect of Na Si O3 addition on the properties of the support was discussed. It was found that the addition of NaSiO3 promoted the sintering of the support at low temperature obviously, but the addition amount needed to be controlled properly. The optimum scheme of nasio3 content, pore-forming agent content, binder content and holding time was determined by orthogonal experiment. Under the optimum conditions, the effect of temperature on the ceramic membrane was studied. The ceramic membrane obtained at 1400-1450 鈩，

本文编号：2293477