Removal of titanium dioxide nanoparticles by coagulation: effects of coagulants, typical ions, alkalinity and natural organic matters

To investigate the possibility of removing titanium dioxide nanoparticles (TiO2 NPs) from water by coagulation, as well as to find the optimal coagulant and experimental conditions for TiO2 NP removal, four types of coagulant were adopted: polyferric sulfate (PFS), ferric chloride (FeCl3), polyalumi...

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Bibliographic Details
Published in:Water science and technology 2013-01, Vol.68 (5), p.1137-1143
Main Authors: WANG, H. T, YE, Y. Y, QI, J, LI, F. T, TANG, Y. L
Format: Article
Language:English
Subjects:
Alkalinity
Alum
Alum Compounds - chemistry
Aluminum Hydroxide - chemistry
Aluminum sulfate
Applied sciences
Biocompatibility
Calcium chloride
Chlorides - chemistry
Coagulants
Coagulants - chemistry
Coagulation
Dosage
Exact sciences and technology
Ferric chloride
Ferric Compounds - chemistry
Humic acids
Hydroxyapatite
Ionic strength
Nanoparticles
Nanoparticles - chemistry
Organic matter
Pollution
Polyferric sulfate
Protective coatings
Removal
Sodium bicarbonate
Sodium chloride
Sodium sulfate
Sulphates
Surgical implants
Titanium
Titanium - chemistry
Titanium dioxide
Water quality
Water treatment and pollution
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Summary:To investigate the possibility of removing titanium dioxide nanoparticles (TiO2 NPs) from water by coagulation, as well as to find the optimal coagulant and experimental conditions for TiO2 NP removal, four types of coagulant were adopted: polyferric sulfate (PFS), ferric chloride (FeCl3), polyaluminum chloride (PACl), and alum (Al2(SO4)3). It was found that the removal of TiO2 NPs by coagulation was affected by ionic strength, alkalinity, as well as types and dosages of coagulants. PFS and FeCl3 achieved much higher removal efficiency of TiO2 NPs than PACl and Al2(SO4)3 did. For 30 mg/L TiO2 NPs, a dosage of 0.3 mM PFS (as Fe) achieved 84% removal after coagulation followed by 30 min settlement. Optimal ionic strength (0.1 M NaCl or 0.03 M CaCl2) is of vital importance for the performance of PFS. Na2SO4 is unfavorable for the performance of PFS. Optimal alkalinity (0.01-0.03 M NaHCO3) is necessary for FeCl3 to remove TiO2 NPs. Natural organic matter, as represented by humic acid (HA) up to 11 mg/L, reduces the removal of TiO2 NPs by coagulation. These findings indicate that coagulation is a good option for the removal of TiO2 NPs from water, and more attention should be paid to the effects of water quality when using coagulation to remove TiO2 NPs from aqueous matrices. This provides a possible solution to alleviate the potential hazard caused by TiO2 NPs.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2013.356