Studies On Preparation And Applications Of Doped Nano-α-FeOOH Flocculants

In the view of the organics mico-pollutants in surface water, the preparations of nano-iron oxide flocculant doped with aluminum or silicon elements, was discussed in this paper. From the aspect of strengthening conventional coagulation unit process, the performance and mechanisms of humic acid removal,was studied as well. Taking the slight polluted water in Cetian Reservoir as an example, the actual processing efficiency of the nano-iron oxide coagulant doped with aluminum, silicon was demonstrated and the main results are as follows:1. Preparation of nano a-FeOOH doped with of aluminum and silicon of different blending ratios. Nano a-FeOOH particles doped with Aluminum is needle-shaped and spindle-shaped, particle size is of 0-100nm, and dispersant in the absence of external circumstances in a good dispersion; nano a-FeOOH particles doped with silicon is spindle-shaped and particle size is of 8-12nm. Nano a-FeOOH added with sodium silicate synthesis in the late time, reaction rate obviously increases.2. Different Blends of nano a-FeOOH doped with aluminum has a high removal rate on the PFOS. The results show that when the dosage is 30mg/L, Al3+/Fe2+molar ratio of 0.15 has the best removal rate of 90.49 percent and acidic environment is conductive to the removal of PFOS. Nano-a-FeOOH doped with Silicon has a high removal rate on PFOS and when the ratio of Si4+/Fe2+is 0.01, the removal rate is much higher.Salinity has a great influence on the adsorption of PFOS.3. Flocculation experiments is made to humic acid simulation water and water from Cetian reservoir with doped a-FeOOH as flocculants.Results show that:nano a-FeOOH doped with aluminum with a A13+/Fe2+ratio of 0.15 has the best removal rate on the humic acid while nano-a-FeOOH doped with silicon in with a Si4+/Fe2+ ratio of 0.01 has the best removal rate. Also,they both have good effect on the removal of pollutants from Cetian reservoir, with a CODmn removal rate of 67.5% and Mn2+ 72%.4. Flocculation experiments are made to water from Cetian reservoir with dopedα-FeOOH and PDADMAC as flocculants. Results show that:TOC removal rate reach 75% when PDADMAC dosage is 1mg/L and doped a-FeOOH nano-aluminum dosage 300mg/L; TOC removal efficiency reach 67% when nano-a-FeOOH doped with silicon dosage is 400 mg/L.