Flocculant containing silicon, aluminum, and starch for sewage treatment

In the present study, a novel combined flocculant comprising starch-capped Na2SiO3·9H2O and Al2(SO4)3·18H2O was successfully synthesized by a process of polymerization and coating. The novel flocculant exhibited high efficiency and ecofriendliness. Experiments on the flocculation of simulated water showed that the flocculant prepared from starch-capped poly-aluminum silicate exhibited excellent performance. The product was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction to analyze its structure and performance. A comparison of its coagulation efficiency in terms of the removal of turbidity and chroma was conducted in experiments. The results show that the flocculant exhibited the highest coagulation efficiency when the aluminum/silicon molar ratio was 1, the starch/Si mass ratio was 1.5, the pH was 1.5, the reaction temperature was 35°C, and the reaction time was 120 min. The rates of removal of turbidity and chroma exceeded 99% and 98%, respectively, under the optimal conditions. © 2020 Society of Chemical Engineers, Japan. All rights reserved.