Abstract
Photocatalytic reduction of toxic Cr(VI) was successfully achieved using carbon modified titanium oxide (CM-n-TiO2) nanoparticles under natural sunlight illumination. Modification of titanium oxide by carbon significantly enhanced the photocatalytic reduction of Cr(VI) under natural sunlight irradiation. The effects of various experimental parameters such as catalyst dose, initial concentration of Cr(VI), and solution pH on the reduction rate of Cr(VI) were investigated. The highest reduction rate of Cr(VI) was obtained at the optimal conditions of pH 5 and 2.0 g·L?1 of CM-n-TiO2. Interestingly, in the presence of phenol, as a sacrificial electron donor, the rate of Cr(VI) reduction was nearly 1.7 times higher than in its absence. The solar photoreduction of Cr(VI) in aqueous solution using CM-n-TiO2 obeyed a pseudo-first order kinetics according to the Langmuir-Hinshelwood model.
Highlights
The discharge of toxic heavy metals into aquatic environment has been known to cause serious pollution problems
Visible light active carbon modified titanium dioxide (CM-n-TiO2) nanoparticals were synthesized by a sol-gel method using titanium butoxide (Ti[O(CH2)3CH3]4, Fluka, 97%), a carbon-containing precursor, as a molecular precursor of TiO2 as well as a carbon source
It is clearly observed that the photocatalytic activity of CM-n-TiO2 is higher than that of n-TiO2 under sunlight irradiation
Summary
The discharge of toxic heavy metals into aquatic environment has been known to cause serious pollution problems. Among these pollutants, chromium possesses the most severe environmental concern due to its high toxicity, potential carcinogenicity, and high mobility in water [1,2]. Different techniques have been reported for the treatments of Cr (VI), such as ion exchange [6], membrane separation [7], physical and biological adsorption [8,9,10], and electrocoagulation [11,12] Most of these techniques have several limitations and drawbacks, and they require either high energy or massive use of reducing agents. Most of the studies on heterogeneous photocatalytic reduction of Cr(VI) using n-TiO2 were performed under illumination of UV light. The effect of presence of phenol, as a sacrificial electron donor, on the photocatalytic reduction of Cr(VI) was investigated
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