Quantum mechanics

Reaction rate constant

Catalysis

Ultraviolet

Carbamazepine

Process (computing)

Engineering

Neuroscience

Biology

Photochemistry

Materials science

Nuclear physics

Water treatment

Operating system

Telecommunications

Computer science

Visible spectrum

Environmental engineering

Physics

Organic chemistry

Irradiation

Epilepsy

Degradation (telecommunications)

Environmental chemistry

Environmental science

Ultraviolet light

Radical

Kinetics

Chemistry

Alkalinity

Photocatalysis

Advanced oxidation process

Optoelectronics

Chlorine

Photodissociation

Environmental Science & Technology

Photolysis of free chlorine (HOCl/ClO–) is an advanced oxidation process (AOP) to produce hydroxyl (HO•) and other radicals for refractory micropollutant degradation. However, HOCl/ClO– is only conducive to activation and production of radicals by ultraviolet (UV) light. For the first time, we show the use of visible light (>400 nm) to produce HO• and ClO•, through use of graphitic carbon nitride (g-C3N4) and photogenerated hvb+, ecb–, and O2•– in the presence of HOCl/ClO–, which was termed visible light g-C3N4-enabled chlorine AOP (VgC-AOP). The VgC-AOP increased the pseudo first-order degradation rate constant of a model micropollutant, carbamazepine, by 16 and 7 times higher than that without g-C3N4 and HOCl/ClO–, respectively, and remained active over multiple use cycles. Effects of water quality [pH, alkalinity, Cu(II), and natural organic matter (NOM)] and the operational conditions (g-C3N4 and HOCl/ClO– concentrations, irradiation wavelength, and dose) were investigated. Of particular significance is its superior performance in the presence of NOM, which absorbs less light at visible light wavelengths and scavenges less surface-bonded reactive species, compared against UV/TiO2 or UV/chlorine AOPs. The VgC-AOP is practically relevant, feasible, and easily implementable and it expands the potential types of light sources (e.g., LEDs and solar light).

Novel Visible Light-Driven Photocatalytic Chlorine Activation Process for Carbamazepine Degradation in Drinking Water