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Degradation of diphenhydramine pharmaceutical in aqueous solutions by using two highly active TiO2 photocatalysts: Operating parameters and photocatalytic mechanism

Paper ID Volume ID Publish Year Pages File Format Full-Text
46699 46445 2012 7 PDF Available
Title
Degradation of diphenhydramine pharmaceutical in aqueous solutions by using two highly active TiO2 photocatalysts: Operating parameters and photocatalytic mechanism
Abstract

In the present work the efficiency of a new TiO2 catalyst (ECT), synthesized by means of an optimized sol–gel method, is studied for degradation of an important pharmaceutical water pollutant, diphenhydramine (DP). Its activity is compared to P25, the benchmark catalyst, produced by Evonik Degussa Corporation, under different catalyst loadings (up to 2.00 g L−1) and initial solution pH (3.0–11.0). The results show that DP is very stable under non-catalytic conditions but complete degradation and considerable mineralization (ca. 60–70%) under near UV to visible irradiation (∼50 mW cm−2) can be achieved in 60 min by selecting the appropriate TiO2 loading. ECT is significantly more active than the benchmark catalyst for loadings higher than 1.00 g L−1 while the pseudo-first order rate constant increased with the initial solution pH from 3.0 to 11.0. The highest rate constant was obtained with ECT at pH 11 (173 × 10−3 min−1 against 116 × 10−3 min−1 for P25). Scavenger agents were used as a diagnostic tool for the analysis of the photocatalytic mechanism and it was possible to prove that holes were crucial active species participating in the photocatalytic mechanism as well as that ECT has a higher availability than P25 to generate reactive radicals, such as hydroxyl (HO•) and hydroperoxyl (HOO•) radicals.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Diphenhydramine pharmaceutical is photorecalcitrant in the absence of a catalyst. ► Heterogeneous photocatalysis leads to its complete conversion in 60 min. ► ECT is an excellent TiO2 photocatalyst for degradation of diphenhydramine. ► Photogenerated holes are the main responsible species in the catalytic process. ► ECT is more efficient than P25 to generate highly reactive oxidant radicals.

Keywords
Diphenhydramine (DP); Heterogeneous photocatalysis; Titanium dioxide; Kinetics; Scavengers for holes and radicals
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Degradation of diphenhydramine pharmaceutical in aqueous solutions by using two highly active TiO2 photocatalysts: Operating parameters and photocatalytic mechanism
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 113–114, 22 February 2012, Pages 221–227
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us