Characterization and coagulation–flocculation performance of a composite coagulant: poly-ferric-aluminum-silicate-sulfate

Abstract

2014): Characterization and coagulation-flocculation performance of a composite coagulant: poly-ferric-aluminum-silicatesulfate, Desalination and Water TreatmentTo link to this article: http://dx. A B S T R A C TComposite coagulant has received widespread attention and research for its excellent coagulation performance in recent years. In this study, a new composite coagulant poly-ferric-aluminum-silicate-sulfate was synthesized using water glass, FeSO 4 ·7H 2 O, Al 2 (SO 4 ) 3 ·18H 2 O, and NaClO 3 , their structures and morphologies were characterized and compared by X-ray diffraction, infrared spectra, and scanning electron microscopy. In addition, to obtain the optimum synthetic conditions resulting in the maximum turbidity removal efficiency, single-factor method was used to examine the parameters such as Si/[Al+Fe], Al/Fe, and aging time by municipal wastewater treatment. The coagulation-flocculation process showed that chemical oxygen demand and turbidity removal efficiency could achieve 77 and 99.4%, respectively, when the optimum synthesis conditions were Si/[Al+Fe], Al/Fe, OH/[Al+Fe], aging time, and reaction temperature of 0.4:1, 3:7, 0.3, 24 h, and 80˚C, respectively. In addition, when the Si/[Al+Fe] of coagulant was 0.2 and 0.4, the coagulant produced lower sludge volume. The result showed that PFASS exhibit superior flocculation effect, and the main mechanisms in reducing the surface charge of colloids are neutralization and adsorption/bridging coagulation-flocculation.

Synthesis and optimization of a novel poly‐silicic metal coagulant from coal gangue for tertiary‐treatment of coking wastewater

“…However, many small crystal particles about 1 µm or less were shown. The aforementioned conclusion is consistent with XRD analysis and both suggest that the new coagulation reagent possesses both amorphous and crystalline phases, which may depend on the Al/Fe/Si molar ratio applied …”

“…In addition, a strong adsorption peak was present at 845 cm ‐1 , which was attributed to the characteristic peaks of Al‐OH‐Al and Fe‐OH‐Fe. The band located at 1103 cm ‐1 was associated with the symmetrical stretching vibrations of Si–O–Al and Si–O–Fe . From the above analysis, the conclusion can be drawn that new chemical species were formed in the PAFSiC samples and the PAFSiC coagulant was a covalently bound complex of iron, aluminum and silicon.…”

“…Figure records the FTIR spectra of the synthesized coagulant under optimized conditions, and the possible chemical bonds present in the coagulants can be identified. The spectra showed that PAFSiC exhibited characteristic bonds at 3500–3000 cm ‐1 and 1631 cm ‐1 , which were assigned to the ‐OH stretching vibration and the vibration of water absorbed, polymerized and crystallized in the coagulants . The peaks at lower wavenumbers (613, 548 and 465 cm ‐1 ) could be assigned to the combination of the bending vibrations of Si‐O, Fe‐O and Al‐O bonds.…”

“…The characterization and coagulation behaviour of these coagulants were also studied. But investigations of the synthesis and optimization of PAFSiC from coal gangue are limited . To the best of our knowledge, the fabrication of a composite coagulant of PAFSiC customized for the tertiary‐treatment of coking wastewater has not been reported.…”

Preparation of an Aluminum and Iron‐Based Coagulant From Fly Ash for Industrial Wastewater Treatment

“…The spectrum exhibited two characteristic bonds at 3435 and 1636 cm −1 , which could be attributed to the stretching vibration of −OH and the vibration of absorbed or complexed water in the coagulant. More importantly, a strong SiOSi peak at 1060.03 cm −1 and SiO peaks related to SiOH at 882.39 and 851.07 cm −1 clearly indicated the solubilization of SiO 2 during acid leaching . The introduction of silicic acid and corresponding hydrolytic forms via polymerization increase the molecular weight of prepared coagulant.…”