Photocatalytic activity evaluation of TiO2 nanoparticles based on COD analyses for water treatment applications: a standardization attempt

• Published in: International journal of environmental science and technology (Tehran) Vol. 13; no. 4; pp. 1077 - 1088
• Main Authors: EL-Mekkawi, D. M., Galal, H. R., Abd EL Wahab, R. M., Mohamed, W. A. A.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-04-2016
• Subjects: Aquatic Pollution; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Science and Engineering; Original Paper; Soil Science & Conservation; Waste Water Technology; Water Management; Water Pollution Control; Chemical oxygen demand (COD); Photocatalytic activity; Water treatment; Organic pollutants; Nanosized TiO; Standard test method
• ISSN: 1735-1472; 1735-2630
• DOI: 10.1007/s13762-016-0944-0

Evaluation of the photocatalytic activities of TiO
2
nanomaterials based on the chemical oxygen demand (COD) analyses under identical experimental conditions was not previously reported. In this work, COD has been selected as an adequate industrial water quality measure toward the establishment of a representative standard test method. The initial COD values of six organic pollutants representing dye, surfactants, phenols and alcohol were set at 30 ± 2 mg/L. Ten of different commercial and synthesized TiO
2
samples representing anatase, rutile and mixed phases were used and characterized. The data of photocatalytic processes were compared to that obtained using the commonly widespread Degussa-P25 TiO
2
(TD). The COD of all pollutants was completely removed by TD at UV exposure dose ≤9.36 mWh/cm
2
. Consequently, the maximum irradiation dose was set at this value in all experiments. The percentages of COD removal as well as the values of the accumulated UV doses required for complete removal of pollutants were measured using the different TiO
2
samples. TiO
2
samples show different performance abilities toward the various pollutants compared to TD. Based on the obtained data, TiO
2
photocatalysts were divided into two categories according to the hydroxyl radical formation rates. Comparison with previous studies reveals that the photocatalytic efficiency evaluation depends on the method of measurement. COD is recommended to be used as an adequate technique of analysis that meets the purpose of water treatment applications.