Preparation and Characterization of Novel Polytitanium Tetrachloride Coagulant for Water Purification

Abstract

Polymeric metal coagulants are increasingly being used to improve coagulation efficiency, yet the research on the development of titanium and particularly polytitanium salts remains limited. This study is the first attempt in the synthesis, characterization, and application of polytitanium salts as coagulants. Polytitanium tetrachloride (PTC) solutions with different basicity values B (OH/Ti molar ratio) were prepared using a slow alkaline titration method. Jar tests were conducted to assess coagulation performance using both synthetic and real raw water samples, and the floc characteristics were monitored online using a laser diffraction particle size analyzer. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) was utilized to identify various Ti species, with the results providing strong evidence of the presence of various hydrolyzed Ti species in the titanium aqueous phase. Compared to titanium tetrachloride (TiCl4), higher or comparable turbidity and organic matter removal efficiency could be achieved by PTC with improved floc characteristics in terms of size, growth rate, and structure. Besides, the water pH after PTC coagulation was significantly improved toward neutral pH. This study indicates that PTC is an effective and promising coagulant for water purification. Besides, the PTC flocculated sludge was able to recycle and produce functional TiO2 photocatalyst.

Floc properties of polyaluminum ferric chloride in water treatment: The effect of Al/Fe molar ratio and basicity

“…The floc growth rate was calculated by the slope of the rapid growth region [16]. In this study, the highest floc growth rate was obtained when Al/Fe = 7:1 and B = 1.5, where the most negative zeta potential was found.…”

“…This behavior is known as reversible breakage, and the flocs are considered to be held by weak inter-particle bonds, such as van der Waals force [15]. However, some researchers have reported some irreversible breakage, which generally occurs when sweep coagulation is the dominant mechanism, and in that case, flocs could not achieve the initial floc size after breakage [16,17].…”

Improvement of wastewater sludge dewatering performance using titanium salt coagulants (TSCs) in combination with magnetic nano-particles: Significance of titanium speciation

“…It can be concluded that pre-hydrolysis was able to effectively improve the on sludge conditioning efficiency of TSCs, and moderate pre-hydrolyzed TSC (TSC 0.5 ) was more effective than other TSCs (Ti 4þ and high-polymeric species) in improving sludge dewatering performance. Zhao et al (2013) suggested that degree of polymerization reached the maximum by raising the B value to 1.5, while it would decrease due to decomposition of hydrolyzed products under alkaline conditions. It should be noted that sludge pH was sharply decreased to 2e3 after addition of TiCl 4 , which might affect the subsequent treatment and disposal of sludge, such as composting, land use and incineration.…”

Flocculation of copper(II) and tetracycline from water using a novel pH- and temperature-responsive flocculants

“…Nevertheless, little information is known so far about these species. Considering that the pre-hydrolyzed species of several metal ions have been proved to exert positive effect on flocculation (Liu et al, 2008;Zhao et al, 2013), it was speculated whether copper(II) also had similar effect, promoting the flocculation of TC. To verify this hypothesis, ESI-TOF-MS, a rapidly advancing technique (Feng et al, 2015), was employed.…”