Water Resources Research Act Program

Details for Project ID 2018PA236B

Photocatalytic Water Purification Under Visible Light: A New Direction For Water Treatment Process

Institute: Pennsylvania
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $22,000 Total Non-Federal Funds: $44,017

Principal Investigators: Dipendu Saha

Abstract: The largest source of water pollution is attributed to different types of organic substances that originate from both industrial and household sources. In the state of Pennsylvania, besides common organic pollutants, several unique varieties of pharmaceutical compounds, hormones and other contaminates of emerging concerns have been detected in different sources and it possesses a serious need for removal of those pollutants. Different water treatment processes that are used to purify water from these organic pollutants possess slow kinetics, and often require large facilities and high set-up and operating costs. Compared to those processes, photocatalytic water purification is a novel and unique technique in which the organic mater is completely disintegrated onto harmless CO2, H2O or other elemental oxides, if they are present, irrespective of their molecular structure. A photocatalyst is a type of semiconductor material with moderate bandgap energy. Upon incidence of a light, usually of ultraviolet (UV) in nature, the electrons from valence band of the material jump to the conduction band thereby creating excess negative charge in the conduction band and holes or positive charge in the valence band. These holes can come in contact with the organic matter to dissociate the corresponding molecules. Titania or titanium dioxide (TiO2) is the most well known photocatalyst, however, as mentioned earlier, it can be activated by UV light only, thereby requiring the additional cost, set-up and complexity of the process. Compared to titania, carbon nitride (C3N4) is a newly discovered photocatalyst that can be activated by visible light only due to its low bandgap energy and hence can be employed with much ease and simple fashion without requiring any additional set up of UV source. Furthermore, carbon nitride is very easy to synthesize, highly stable, inert and non-toxic. The objective of the proposed is to investigate the photocatalytic decomposition of organic pollutants in water as a function of their chemical structure by carbon nitride under visible light irradiation. In the course of pursuing this objective, four representative types of organic pollutants will be chosen, (i) Non-halogenated aromatic molecule, (ii) Halogenated aromatic molecule, (iii) Non-halogenated aliphatic molecule, (iv) Halogenated aliphatic molecule. In order to further enhance the photocatalyst activity of carbon nitride, a photoinitiator will also be introduced in the system and the disintegration of the organic pollutant will be monitored. The other tasks of the project include measuring the dissociation kinetics, mathematical model fitting of the kinetics, detecting the molecular fragments of the organic pollutants and monitoring the structural stability of carbon nitride under this process. Upon successful completion of the project, such can be used anywhere, like in open sun outside or even in indoor facilities by the presence of regular light source and hence can be installed very easily in both industrial and household sectors. The visible light photocatalysis of carbon nitride to dissociate organic pollutant may provide a new direction in the water treatment process.