Nanoscale Pac Preparation And Purification Separation

Based on the previous research achievements in this laboratory, the preparation, characterization, and purification of Alo were investigated in detail in this thesis. Various methods have been carried out on the preparation of PAC, which has been characterized for the speciation distribution by using Perron assay. Further experiments were then carried out on the optimum separation of the most important species-Al13 in PAC. The main results have been reached as following:1. The PAC samples were prepared using alkalinity titration method under normal laboratory conditions. The speciation and quantity of Al13 were decided largely by basicity. It was also favorable for the yield of Al13 under slow titration rate by avoiding the local high concentration of alkalinity. As result, the base drop could be dissolved rapidly without forming A1(OH)3 precipitation. It is observed that the quantity of Alb could be largely improved at B=2.5 under moderate high temperature (80@). The low speed reaction part in PAC during Perron assay is formed through aggregation of Alb instead of Al(OH)3.2. The basicity exhibits significant role in the reaction of PAC with sulfate. Increase the basicity, the speed of precipitation/crystallization is largely increased. The SO42-7/Al in the solids formed decreases with the increase of basicity. The morphology of solids formed differs markedly among the various PAC. The various species in PAC exhibit quite different ratio in reacting with sulfate. It is therefore possible to separate the various species in PAC by reacting with sulfate. It is observed that the SO4/Al ratio of 1:1 is optimum for the separation of Al13 from the B=2.2 PAC.3. The complicated components of PAC species result in the complicated reaction pathways of sulfate with PAC and reaction products as well. The purification of Al13 is then different for the subsequent reaction of Ba with the various precipitates. The mole ratio of Ba2+/SO42-, ultrasonic reaction time, temperature and dispersion of precipitates have significant influence on the yield of Al13. The wet method exhibits some efficiency against the power method. A Ba2+/SO42" ratio of 1:1 is enough to separate the Al13 in the precipitates.