UV/TiO2 and UV/TiO2/chemical oxidant processes for the removal of humic acid, Cr and Cu in aqueous TiO2 suspensions

• Published in: Environmental technology 2009-03, Vol.30 (3), p.225-232
• Main Authors: Jung, J.-T., Choi, J.-Y., Chung, J., Lee, Y.-W., Kim, J.-O.
• Format: Article
• Language: English
• Subjects: Applied sciences; Catalysis; Catalytic reactions; Chemical engineering; Chemistry; Chromium - chemistry; Copper - chemistry; Equipment Design; Exact sciences and technology; General and physical chemistry; hazardous heavy metals; Humic Substances; hydrogen peroxide; Hydrogen-Ion Concentration; Kinetics; Metals, Heavy - chemistry; Oxidants - chemistry; ozone; Photochemical Processes; Pollution; Reactors; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Titanium - chemistry; Ultraviolet Rays; UV/TiO
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330802503750

The objective of this study was to investigate the treatment efficiency of UV/TiO 2 and UV/TiO 2 /chemical oxidant processes for the removal of humic acid and hazardous heavy metals in aqueous TiO 2 suspensions. The reaction rate (k) of humic acid and hazardous heavy metals by UV/TiO 2 was higher than that of UV illumination alone or TiO 2 alone. The removal efficiency for humic acid and Cr(VI) at acid or neutral pH values was higher than that at basic pH values. However, the removal efficiency for Cu(II) at acid pH values was smaller compared with that at neutral or basic pH values. The reaction rate (k) of humic acid and hazardous heavy metals in the TiO 2 concentration range of 0.1-0.3 g l −1 increased with increasing TiO 2 dosage. However, amounts higher than a TiO 2 dosage of 0.3 g l −1 reduced the removal efficiency for humic acid and hazardous heavy metals because of the shielding effect on the UV light penetration in the aqueous solution caused by the presence of excessive amounts of TiO 2 . The addition of oxidants to the UV/TiO 2 system showed an increase in degradation efficiency for the treatment of humic acid and hazardous heavy metals. The optimal concentration of oxidants was: H 2 O 2 50 mg l −1 , O 3 20 g m −3 and K 2 S 2 O 8 50 mg l −1 , respectively. The degradation efficiency of UV/TiO 2 /oxidant systems for the removal of humic acid and hazardous heavy metals was much greater when H 2 O 2 was used as the oxidant.