论文部分内容阅读
采用高场27AlNMR技术和Al-Ferron逐时络合比色法,系统地研究了总铝浓度(CAlT)对水解聚合铝溶液中Keggin结构的纳米Al13,Al30形态分布及其转化过程的影响.结果表明,在低温(80℃)及Al13的最佳制备碱化度(B)条件下,高总铝浓度的聚合铝溶液中生成的纳米Al13形态趋于进一步聚合转化为Al30或更高聚合形态,总铝浓度愈高,转化速度越快,当CAlT>0.75mol·L?1时,Al13含量急剧减少,Al30含量逐步增加,成为水解聚合铝溶液中的优势纳米聚合形态,但Al13并不定量转化为Al30形态.铝单体的存在是Al13转化为Al30形态的必要条件之一.当溶液CAlT升高或碱化度降低时,一方面Al13与铝单体水解聚合反应速率加快,另一方面溶液pH值降低,加快了Al13及Al30的酸性分解速率;低碱化度,高CAlT溶液中,后者占主导作用,导致Al30含量随CAlT的增大而减小.只有在CAlT<0.5mol·L?1和Al13的最佳制备B值条件下,才能制得高Al13含量(80%以上)的水解聚合铝溶液.
The effect of total aluminum concentration (CAlT) on the morphology distribution and transformation of nano-Al13, Al30 of Keggin structure in hydrolyzed polyaluminum solution was systematically studied by using high-field 27 AlNMR technique and Al-Ferron time-lapse complexometric method. It shows that the morphology of nano-Al13 formed in the polyaluminum solution with high total aluminum concentration tends to be further polymerized into Al30 or higher polymerized form under the optimal preparation alkalization degree (B) of Al13 at low temperature (80 ℃) When the concentration of total aluminum was higher, the conversion rate was faster. When CAlT> 0.75mol·L-1, Al13 content decreased sharply and Al30 content gradually increased, which became the predominant nano-aggregate morphology in hydrolyzed polyaluminum solution. However, Al13 was not quantitatively converted Al30 form the presence of aluminum monomer Al13 is transformed into the form of Al30 one of the conditions.When the solution CAlT increased or decreased alkalinity, on the one hand Al13 and aluminum monomer hydrolysis polymerization reaction rate, on the other hand, the solution pH value decreased, accelerating the acidic decomposition rate of Al13 and Al30; low alkalinity, high CAlT solution, the latter dominated, resulting in Al30 content decreases with increasing CAlT only CAlT <0.5mol · L ? 1 and Al13 best preparation B value conditions, in order to obtain high Al13 containing (Over 80%) of the hydrolyzed aluminum solution polymerization.