Photocatalytic Mechanisms for Peroxymonosulfate Activation through the Removal of Methylene Blue: A Case Study

Jorge Rodríguez-Chueca, Esther Alonso and Devendra Narain Singh
Additional contact information
Jorge Rodríguez-Chueca: Department of Industrial Chemical & Environmental Engineering, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, Calle José Gutiérrez Abascal 2, 28006 Madrid, Spain
Esther Alonso: Department of Industrial Chemical & Environmental Engineering, Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, Calle José Gutiérrez Abascal 2, 28006 Madrid, Spain
Devendra Narain Singh: Department of Civil Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076, India

IJERPH, 2019, vol. 16, issue 2, 1-13

Abstract: Industrial activity is one of the most important sources of water pollution. Yearly, tons of non-biodegradable organic pollutants are discharged, at the least, to wastewater treatment plants. However, biological conventional treatments are unable to degrade them. This research assesses the efficiency of photocatalytic activation of peroxymonosulfate (PMS) by two different iron species (FeSO 4 and Fe 3+ -citrate) and TiO 2 . These substances accelerate methylene blue removal by the generation of hydroxyl and sulfate radicals. The required pH and molar ratios PMS:Fe are crucial variables in treatment optimization. The kinetic removal is reduced by the appearance of scavenger reactions in acidic and basic conditions, as well as by the excess of PMS or iron. The best performance is achieved using an Fe 3+ -citrate as an iron catalyst, reaching the total removal of methylene blue after 15 min of reaction, with a molar ratio of 3.25:1 (1.62 mM of PMS and 0.5 mM Fe 3+ -citrate). Fe 3+ -citrate reached higher methylene blue removal than Fe 2+ as a consequence of the photolysis of Fe 3+ -citrate. This photolysis generates H 2 O 2 and a superoxide radical, which together with hydroxyl and sulfate radicals from PMS activation attack methylene blue, degrading it twice as fast as Fe 2+ (0.092 min −1 with Fe 2+ and 0.188 min −1 with Fe 3+ -citrate). On the other hand, a synergistic effect between PMS and titanium dioxide (TiO 2 ) was observed ( S PMS/TiO2/UV-A = 1.79). This synergistic effect is a consequence of PMS activation by reaction with the free electron on the surface of TiO 2 . No differences were observed by changing the molar ratio (1.04:1; 0.26:1 and 0.064:1 PMS:TiO 2 ), reaching total removal of methylene blue after 80 min of reaction.

Keywords: sulfate radicals; peroxymonosulfate; iron activation; TiO 2 activation; dye; synergistic effect (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

Downloads: (external link)
https://www.mdpi.com/1660-4601/16/2/198/pdf (application/pdf)
https://www.mdpi.com/1660-4601/16/2/198/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jijerp:v:16:y:2019:i:2:p:198-:d:197026

Access Statistics for this article

IJERPH is currently edited by Ms. Jenna Liu

More articles in IJERPH from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().