Preparation and Characterization of a Composite Coagulant: Polyferric Titanium Sulfate

Abstract

In this study, a novel composite coagulant polyferric titanium sulfate (PFTS) was synthesized and the kaolin-fulvic acid simulated water was employed to verify the coagulation efficiency. To obtain the optimal conditions for preparing the composite coagulant, the parameters affecting the coagulation performance such as Ti/Fe, P/Fe, OH/Fe, and oxidizer dosage were evaluated by single factor experiments and response surface methodology. The structure and morphology of PFTS were investigated by some conventional methods and those affecting coagulation-flocculation behaviors such as coagulant dosage, water sample initial pH, were also examined. Flocs properties of PFTS were investigated by Mastersizer 2000. The results indicated that PFTS presented a porous and a compacted gel network structure, in which some major phase structure and chemical bonds were discovered. The jar tests demonstrated the superior coagulation performance at coagulant dosage of 20-30 mg/L and the optimum pH range of 7-8. The optimum synthetic conditions were Ti/Fe, P/Fe, OH/Fe molar ratio and oxidant adding speed of 0.13, 0.25, 0.29, and 4 mL/min, respectively. Under the optimal condition, the residual turbidity, (Dissolved organic matter) DOC removal and residual iron of 0.82, 53 %, and 0.08 mg/L, respectively, could be acquired by PFTS. The flocs analysis results manifested that the dominant mechanism in flocs growth is absorption-bridging and sweeping coagulation, while charge neutralization mechanisms is the primary in the formation of compact flocs.

Structure, Morphological, and Physicochemical Characteristics of a New Composite Coagulant Made From Polyaluminium Chloride and Agro-waste of Tapioca Peel

“…In PAC, the tridecamer of Al 13 [69,70]. Nevertheless, the peak of Al 13 species in PAC products could not be proven without any modi cation;…”

“…It is assumed that high molecular weight coagulants are more effective in improving the bridge formation capability among colloidal particles [10] due to the intrinsic unity of relation among the oc properties under various coagulation mechanisms. The newly developed composite coagulants also imposed functional groups that are useful as coagulating agents as studied by Yang et al [11], Wang et al [12], Chen et al [13], Li et al [14], Chen et al [15], and Huang et al [9]. Table 1 highlights the characteristics of new composite coagulants of the identi ed functional groups through FTIR analysis from previous studies.…”

“…Based on the observation in Figure 9, it is clear that the spectrum of PACTPPg is slightly similar to TPP but not the complete combination of PAC and TPP spectra, which has broader and denser intense bands, especially in the range of 3500-2500 cm -1 . The broader and denser intense band is due to the intermolecular stretching vibration of dissociative -OH [9,13,75], since PACTPPg was prepared through the dilution of PAC and TPP in distilled water, and then dried for the adsorption spectrum analysis. The functional group consists of -OH is one of the important factors to indicate the e ciency of coagulants [13].…”

“…The broader and denser intense band is due to the intermolecular stretching vibration of dissociative -OH [9,13,75], since PACTPPg was prepared through the dilution of PAC and TPP in distilled water, and then dried for the adsorption spectrum analysis. The functional group consists of -OH is one of the important factors to indicate the e ciency of coagulants [13]. Next, it is observed that the peak of 3231.46 cm -1 belongs to the wide-ranging bands of 3600-3100 cm -1 and 3500-3100 cm -1 that respectively assigned to alcohols, phenols, and amines-secondary functional groups [25,44], which appear with strong O-H stretching and medium N-H bend intensities, respectively.…”

“…Next, near the 1400 cm -1 wavelength, the absorption peaks appeared on PACTPPg and TPP, but it did not appear in PAC. According to Chen et al [13], who developed a new composite coagulant of polyferric-aluminium-silicate-sulphate, it could be deduced that the peaks were assigned to Al-O-Al bond stretching and bending vibration. Simultaneously, the peaks between 1359.32 and 1151.24 cm -1 (Appendix) could indicate the sign of Si-O-Si bonds [9].…”