The influence of solution matrix on the photocatalytic removal of color from natural waters

Abstract

Photocatalytic color removal of humic acid was studied in the presence of common inorganic anions; namely, chloride, nitrate, sulfate and phosphate ions at pH 6.8. Color removal rates were explained in terms of pseudo-first order and Langmuir-Hinshelwood kinetics. The Freundlich adsorption data were also evaluated to assess a relationship between the adsorption data and the reaction kinetics. The presence of chloride, nitrate and sulfate ions exhibited different trends when the rate is expressed as pseudo-first order reaction kinetics. In case of Langmuir-Hinshelwood kinetics, the decolorization rates were decreased in the order of the anions as, chloride, nitrate and sulfate. The presence of phosphate ions strongly inhibited the color removal rate.

Heterogeneous Photocatalysis: Recent Advances and Applications

“…TiO 2 as a semiconductor photocatalyst, has excellent pigmentary properties, high ultraviolet absorption and high stability which allow it to be used in different applications such as electro-ceramics, glass and in the photocatalytic degradation of chemicals in water and air. It has been used in the form of a suspension, or a thin film in water treatment [22,23] and has different crystalline forms, the most common forms being anatase and rutile while the third, brookite, is uncommon, unstable and hence does not feature in discussion of catalyst materials.…”

“…The environmental applications of heterogeneous photocatalysis include removing heavy metals such as (Hg), chromium (Cr), lead (Pb), Cadmium (Cd), lead (Pb), Arsenic (As), nickel (Ni) copper (Cu). The photoreducing ability of photocatalysis has been used to recover expensive metals from industrial effluent, such as gold (Au), platinum (Pt) and silver (Au) [22].…”

“…Water contaminated by oil can be treated efficiently by photocatalytic reaction. Herbicides and pesticides that may contaminate water such as 2,4,5 trichlorophenoxyacetic acid, 2,4,5 trichlorophenol, S-triazine herbicides and 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) have also been successfully degraded [22].…”

“…Inorganic species such as bromate, or chlorate, azide, halide ions, nitric oxide, palladium and rhodium species, and sulfur species can be decomposed. Metal salts such as AgNO 3 , HgCl and organometalic compound (e.g., CH 3 HgCl) can be removed from water as well as cyanide, thiocyanate, ammonia, nitrates and nitrites [22].…”

Heterogeneous Photocatalytic Oxidation an Effective Tool for Wastewater Treatment – A Review

“…Photocatalytic degradation studies utilizing Degussa P25 have been well documented due to its chemical stability, readily availability, reproductive ability, and activity as a catalyst for oxidation process (Bekbolet et al, 1998;Bekbolet & Balcioghu, 1996;Saravanan et al, 2009). Vigorous activities and researches are in process to further develop the existing Degussa P25 or synthesizing new materials, which can initiate photocatalysis using solar energy and hence reduce the cost and shortening the total time needed for the degradation.…”