Synthesis, purification and characterization of polyaluminum ferric chloride (PAFC) with high (Al + Fe)b content

Taking blast furnace dust and aluminum dross as raw material, PAFC with high (Al + Fe)b content was prepared via optimizing Al/Fe molar ratio and basicity condition in this study. Separation, purification and characterization of (Al + Fe)b were further investigated. The results showed that the (Al + Fe)b content in PAFC peaked at 36.67% with Al/Fe = 7:3 and basicity(B)=1.8. The optimal conditions for purifying (Al + Fe)b by the organic solvents precipitation method were determined as follows: organic solvents (ethanol, propylene glycol and acetone mixed solution) volume ratio = 2:1:7. An organic mixed solution in measures of 50 mL, 100 mL and 50 mL was added into 10 mL of 0.3 M PAFC solution to extract (Al + Fe)c, (Al + Fe)b and (Al + Fe)a, respectively. The (Al + Fe)b content in the separated samples reached over 75% with the yield higher than 50% of the total PAFC. The infrared spectrum of the extracted (Al + Fe)b, PAFC, and commercial PAC showed that the content of hydroxyl bridge linked aluminum/iron in the extracted (Al + Fe)b sample was higher than those in PAC and PAFC. The transmission electron microscope images of the extracted (Al + Fe)b suggested a 3D network structure of the (Al + Fe)b with rough surfaces, which benefits adsorption and sweep of contaminants. Coagulation tests showed that the extracted (Al + Fe)b achieved better coagulation performance than PAFC and commercial PAC.