Solar-energy-enabled photocatalysis degrades persistent contaminants and promotes sustainable water treatment by reducing energy and chemical demand for water treatment. Graphitic carbon nitride (g-C3N4) has emerged as a novel polymeric photocatalyst because of its response to visible light and utilization of more renewable solar energy (up to 40% of solar energy), facile synthesis from earth abundant materials, great thermal and chemical stability, and little to none-existent toxicity; however its application in water purification is largely underexplored. Here, we developed supramolecule-based g-C3N4 from melamine, cyanuric acid, and barbituric acid with significantly improved surfaced area and charge separation compared to bulk g-C3N4 synthesized only from melamine. The photocatalytic degradation kinetics was evaluated for the removal of a model contaminant, phenol, and persistent contaminants, atrazine, carbamazepine, and sulfamethoxazole under visible light irradiation in a model aqueous system, simulated complex water matrices, and water samples representing different stages of water/wastewater treatment. The supramolecule-based g-C3N4 showed an improved reactivity up to 10 folds compared to the bulk g-C3N4 for atrazine degradation. The chemistries of simulated natural water and partially treated water/wastewater had little to no inhibition on atrazine degradation kinetics compared to the model buffer system. Moreover, we performed atrazine degradation on g-C3N4 under light emitting diode (LED) irradiation to evaluate the feasibility of using energy-efficient, artificial light sources for photocatalytic water treatment, and a comparable photocatalytic activity was achieved under multichromatic white LED irradiation and Xenon lamp irradiation (&gt; 400 nm). The increase of photocatalytic activity under irradiation at a shorter wavelength is in agreement with the optical absorption spectrum of g-C3N4. In summary, visible-light-responsive g-C3N4 is promising for the removal of persistent contaminants under both solar and LED irradiation, and its application will pave a new avenue for addressing the challenges in water sustainability.

Achieving sustainable water purification: Visible light-responsive, graphitic carbon nitride for the removal of persistent contaminants

251st National Meeting (2016)

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