Abstract
A novel chlorine-free coagulant of polyferric-silicate-acetate (PFSA) with varying Si/Fe molar ratios was applied to treat Congo red (CR) dye wastewater in order to determine its coagulation ability and performance. Images obtained from Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR) analysis revealed the functional group and morphology of PFSA. The results showed that the CR removal efficiency was the best at the Si/Fe molar ratio 1:1. According to the analysis of FTIR and SEM, PFSA was a polymeric complex containing polyferric-silicate-acetate polymer and hydroxyl iron oxide, which presented closely clustered rod shaped with many particles on its surface. Compared with polyferric acetate (PFC) and polysilicic acid (PSA), PFSA was more efficient and had a broader pH range of 5.5–10. The highest CR removal efficiencies recorded for PFSA, PFC and PSA were 93.6%, 88.3% and 70.4%, respectively. In addition, PFSA and PFC had wider range of temperature at optimal conditions. The analysis of coagulation properties revealed that the mechanisms of adsorption-bridging and enmeshment coagulation acted a crucial role in the coagulation process of PFSA. Therefore, PFSA will be a promising green-coagulant for treating actual wastewater containing refractory dyes, which can reduce environmental risk.
Published Version
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