Zinc oxide nano-enabled microfluidic reactor for water purification and its applicability to volatile organic compounds

• Published in: Microsystems & nanoengineering Vol. 4; no. 1; p. 17093
• Main Authors: Azzouz, Imadeddine, Habba, Yamina Ghozlane, Capochichi-Gnambodoe, Martine, Marty, Frédéric, Vial, Jérôme, Leprince-Wang, Yamin, Bourouina, Tarik
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.02.2018; Springer Nature B.V; Springer Nature
• Subjects: 639/166; 639/301/357; Benzene; Biodegradation; Catalysis; Chemical engineering; Chemical Sciences; Contaminants; Contamination; Decontamination; Dilution; Drinking water; Engineering; Environmental Engineering; Environmental protection; Environmental Sciences; Ethylbenzene; Evaporation; Microfluidics; Nanomaterials; Nanotechnology; Nanowires; Organic compounds; Photocatalysis; Photodegradation; Pollutants; Purification; Toluene; VOCs; Volatile organic compounds; Water flow; Water purification; Xylene; Zinc oxide; Zinc oxides; Ethylbenzene; Benzene; Toluene; water purification; o-Xylene (BTEX); volatile organic compounds (VOCs); m-p Xylenes; zinc oxide nanowires; microfluidic reactor
• ISSN: 2055-7434; 2096-1030; 2055-7434
• DOI: 10.1038/micronano.2017.93

This paper reports fast and efficient chemical decontamination of water within a tree-branched centimeter-scale microfluidic reactor. The microreactor integrates Zinc oxide nanowires (ZnO NWs) in situ grown acting as an efficient photocatalytic nanomaterial layer. Direct growth of ZnO NWs within the microfluidic chamber brings this photocatalytic medium at the very close vicinity of the water flow path, hence minimizing the required interaction time to produce efficient purification performance. We demonstrate a degradation efficiency of 95% in <5 s of residence time in one-pass only. According to our estimates, it becomes attainable using microfluidic reactors to produce decontamination of merely 1 l of water per day, typical of the human daily drinking water needs. To conduct our experiments, we have chosen a laboratory-scale case study as a seed for addressing the health concern of water contamination by volatile organic compounds (VOCs), which remain difficult to remove using alternative decontamination techniques, especially those involving water evaporation. The contaminated water sample contains mixture of five pollutants: Benzene; Toluene; Ethylbenzene; m–p Xylenes; and o-Xylene (BTEX) diluted in water at 10 p.p.m. concentration of each. Degradation was analytically monitored in a selective manner until it falls below 1 p.p.m. for each of the five pollutants, corresponding to the maximum contaminant level (MCL) established by the US Environmental Protection Agency (EPA). We also report on a preliminary study, investigating the nature of the chemical by-products after the photocatalytic VOCs degradation process. Microfluidics: Low-cost microreactors for purifying contaminated water A technique for making photocatalytic microfluidic reactors could lead to the faster and more efficient purification of contaminated water. Drinking water contaminated with pollution from the environment and waterborne agents of disease, including VOCs, is a major cause of ill health and death. The search for water-purification systems has led researchers to look to lab-on-chip technologies such as ultracompact optofluidic microreactors because of their low cost, rapid fabrication, easy flow control and large surface-to-volume ratios. Yamin Leprince-Wang, Tarik Bourouina and colleagues at the Université Paris-Est in France have developed such a microfluidic reactor that uses zinc-oxide nanowires as a photocatalytic nanomaterial layer for purifying water. By growing the nanowires in the microfluidic chamber, the photocatalytic medium is in close proximity to the path of the water flow, greatly increasing the efficiency of the purification process.