Preparation of aluminum-ferric-magnesium polysilicate and its application on oily sludge

Aluminum-ferric-magnesium polysilicate (PAFMS) was prepared by introducing aluminum, ferric and magnesium metal ions into Polymer silica acid solution. PAFMS was applied in the treatment of oily wastewater from treatment of oily sludge in this paper, and the coagulation performance was valued by the removal efficiency of turbidity and colority. The structure and morphology of PAFMS were characterized by the Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD) and Scanning Electronic Microscopy (SEM). The results indicated that mole ratios 6:4:15 of Al:Fe:Mg is beneficial to forming of Al-O-Si, Fe-O-Si and Mg-Si-O. Fe played main inhibition role among the three metals. XRD analysis showed that the addition of Al, Fe and Mg into Polysilicon acid did not produce a simple mixture, but resulted in the formation of new chemical structures. The intensity of peaks was influenced by the mole ratios of metals. SEM spectra presented that PAFMS appeared to be a spatial structure consisting of many irregular protuberant parts. The removal efficiency of turbidity and colority in oily water from the treatment of oily sludge was better when the mole ratio of (Al+Fe+Mg):Si was 0.5 and if the mole ratios of Al:Fe:Mg are kept at 6:4:15. Moreover, when the dosage of PAFMS was 1.4-1.8 % and the pH value in range of 8-9, the efficiency of turbidity and colority removal are up to 97.3 and 96.8%, respectively.