Aqueous mercury adsorption by activated carbons.

Microwave synthesis of a novel magnetic imprinted TiO2 photocatalyst with excellent transparency for selective photodegradation of enrofloxacin hydrochloride residues solution

Heterogeneous photocatalysis is a promising technology especially for environmental remediation. Despite more than a decade of worldwide research in developing photocatalytic efficiency improving techniques, many questions regarding the large scale application of photocatalytic reactors still remain unanswered. Recently, improving the photocatalytic efficiency has gained scientific attention because it might lead to more economical and robust photocatalytic operation for environmental remediation. In this review, fundamental and comprehensive assessments of the photocatalytic concepts and their applications for environmental remediation are reviewed. The existing challenges and strategies to improve the photocatalytic efficiency are discussed. Further, recent developments and future research prospects on photocatalytic systems for environmental applications are also addressed.

Photocatalytic systems as an advanced environmental remediation: Recent developments, limitations and new avenues for applications

Inorganic-framework molecularly imprinted TiO2/WO3 nanocomposites with molecular recognitive photocatalytic activity were first prepared successfully by a facile one-step sol-gel method using 2-nitrophenol and 4-nitrophenol as template molecules, and tetrabutyl orthotitanate as titanium source as well as the precursor of functional monomer which could complex with template molecules. The template molecules could be completely removed by means of high-temperature calcination, avoiding the traditional extraction procedures that are time- as well as solvent-consuming. Compared to nonimprinted TiO2/WO3, the molecularly imprinted TiO2/WO3 shows a much higher adsorption capacity and selectivity toward the template molecules. The enhancement in terms of adsorption capacity and selectivity can be attributed to the chemical interaction between target molecules and imprinted cavities, as well as size matching between imprinted cavities and target molecules. The photocatalytic activity of molecularly imprinted TiO2/...

Facile One-Step Synthesis of Inorganic-Framework Molecularly Imprinted TiO2/WO3 Nanocomposite and Its Molecular Recognitive Photocatalytic Degradation of Target Contaminant

An intensive study on the magnetic effect of mercapto-functionalized nano-magnetic Fe3O4 polymers and their adsorption mechanism for the removal of Hg(II) from aqueous solution

The photocatalytic removal of Hg(II) from aqueous solutions of HgCl 2 using TiO 2 as catalyst was studied. The influence of pH and the addition of methanol, formic acid and oxalic acid as sacrificial additives on the extent of Hg(II) adsorption and photocatalytic reduction was investigated. The results showed that the overall process strongly depended on pH, being enhanced as the pH was increased. At pH 10, an efficient removal of Hg(II) was achieved even in the absence of organic additives, attaining final mercury concentrations in solution at trace levels (μg L −1 ). In acidic conditions, the addition of sacrificial organic molecules significantly increased the rate and extent of aqueous Hg(II) removal. The nature and distribution of mercury products deposited on the catalyst was dependent on the reaction conditions. In the absence of additives, Hg 2 Cl 2 and Hg 0 were respectively identified in acidic and neutral/alkaline media as main reduced species on the titania surface. The addition of organic additives enhanced the photocatalytic reduction to Hg 0 . Comparison between adsorption and reaction results evidenced that it cannot be established a direct correlation between Hg(II) dark adsorption on the TiO 2 surface and the efficiency of Hg(II) photoreduction achieved.

R. Pascual

Papers

Mercury removal from aqueous solutions of HgCl2 by heterogeneous photocatalysis with TiO2