Preparation and Characterization of Titanium Dioxide (TiO₂) from Sludge produced by TiCl₄Flocculation with FeCl₃, Al₂(SO₄)₃and Ca(OH)₂Coagulant Aids in Wastewater

Abstract

In this study, TiCl 4 coagulant together with coagulant aids such as FeCl 3 , Al 2 (SO 4 ) 3 , and Ca(OH) 2 were investigated to improve the photoactivity of titanium dioxide (TiO 2 ) produced from sludge and to increase the resulting low pH value. After TiCl 4 flocculation with three coagulant aids, the settled floc (sludge) was incinerated at 600 C to produce TiO 2 doped with Fe, Al, and Ca elements. Fe-, Al-, and Ca-doped TiO 2 was characterized in terms of structural, chemical, and photo-electronic properties. All the coagulant aids used together with Ti-salt flocculation effectively increased the pH values. The surface area of TiO 2 -WO (without any coagulant aids), Fe=TiO 2 , Al=TiO 2 , and Ca=TiO 2 was 122 m 2 =g, 77 m 2 =g, 136 m 2 =g and 116 m 2 =g, respectively. The TiO 2 -WO, Fe=TiO 2 , Al=TiO 2 , and Ca=TiO 2 was found to be of anatase phase. The XRD pattern on the Fe=TiO 2 included an additional peak of hematite (a-Fe 2 O 3 ). The majority of gaseous acetaldehyde with TiO 2 -WO and Ca=TiO 2 for photocatalytic activity was completely removed within 40 minutes under UV irradiation.

Effect of shear force, solution pH and breakage period on characteristics of flocs formed by Titanium tetrachloride (TiCl4) and Polyaluminum chloride (PACl) with surface water treatment

“…In addition, the main drawback of the flocculation process using aluminum salt coagulants is a large amount of sludge produced, which still needs to be disposed of either into landfills or dumped into the ocean. To resolve the problem of sludge disposal, Shon et al used TiCl 4 as a coagulant and the Ti-salt flocculated sludge was recycled to produce valuable by-product namely TiO 2 [20,21]. TiO 2 was the most widely used metal oxide for environmental applications as photocatalyst, cosmetics, paints, electronic paper, and solar cells [20,22,23].…”

Coagulation characteristics of titanium (Ti) salt coagulant compared with aluminum (Al) and iron (Fe) salts

“…To resolve the sludge disposal problem, a novel process has been recently developed by Shon et al [10]. Titanium tetrachloride (TiCl 4 ) was used as a coagulant, the most significant advantage of which is the possibility of recovering the sludge to produce a valuable by-product namely titanium dioxide (TiO 2 ) [11]. TiO 2 is the most widely used metal oxide, whose applications include photocatalysts, cosmetics, paints, electronic paper, and solar cells [12,13].…”

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

“…TSC exhibited better hydrolytic stability and coagulation performance for NOM and turbidity removal (Tomaszewska et al, 2004). In addition, the residuals produced from titanium salt coagulation can be converted into TiO 2 materials through high-temperature calcination (Shon et al, 2009a(Shon et al, , 2009bKim et al, 2011), which is known to be an environmentally friendly photocatalyst. Nano materials, especially nano oxides have exhibited excellent physical and chemical properties and have many advantages over traditional adsorption materials, so they attracted much attention in recent years (Liang et al, 2004).…”

“…And it has many advantages of larger floc, low dosage and more settleable than traditional iron and aluminum salts coagulation etc. (Shon et al, 2009a(Shon et al, , 2009b. Due to its strongly hydrolytic and acidic properties, addition of TiCl 4 would cause serious acidification of water.…”