Wavelength-dependent chlorine photolysis and subsequent radical production using UV-LEDs as light sources

Investigation of the efficacy of the UV/Chlorine process for the removal of trimethoprim: Effects of operational parameters and artificial neural networks modelling

“…Collectively, the UV-LED 275 systems triumphed all other UV systems in the application of chlorine photolysis of at alkaline pHs. The k f ′ trend obtained is not congruent with Yin et al's hypothesis (Yin et al, 2018) If chlorine photo decay rates were extremely dependent on their molar absorption coefficients (ε), the performance of chlorine photolysis would have been: UV(310)/Cl 2 > UV(275)/Cl 2 > UV(265)/Cl 2 > UV (254)/Cl 2 because ε OCl, 310 > ε OCl, 275 > ε OCl, 265 > ε OCl, 254 (Fig. S3).…”

“…7A shows that k f ′ had an upward trend as pH was increased -deviating from the trend observed at 254 nm. Yin et al (2018) propounded that the wavelength dependency of chlorine photolysis on its molar absorption coefficients were higher at alkaline pHs -indicating that (free) chlorine photo decay rates were more dependent on their molar absorption coefficients (ε) than their quantum yields (Φ). Since OClhas a higher molar absorption coefficient compared to HOCl at Table 5 The performance of the generated models with different hidden layer sizes and learning rates through 30 iterations.…”

“…This implies that chlorine photolysis could have a higher dependency on not only molar absorptivity, but also its quantum yields at higher pH. The trend in quantum yields of OClacross different wavelengths (Φ OCl, λ ) is the polar opposite to its molar absorption coefficient: Φ OCl, 254 = 1.058 > Φ OCl, 265 = 0.995 > Φ OCl, 275 = 0.937 > Φ OCl, 310 = 0.737 (Yin et al, 2018). Although OCl − at 275 nm does not have the highest molar absorption coefficient (as compared to 310 nm) nor does it have the highest quantum yield to decompose the most OClto form radical chlorine species upon UV irradiation (as compared to 254 nm), the UV(275)/Cl 2 systems provide a sweet spot for OClto have the best of both worlds.…”

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

“…The flow rate was 1.0 mL/min and the mobile phase was a mixture of water (pH 3, adjusted using phosphoric acid) and methanol (55/45, v/v %). 40 The detection limits of CBZ, NB and BA are 0.06, 0.10, 0.04 and 0.13 μM, respectively.…”

From Conventional Disinfection to Antibiotic Resistance Control—Status of the Use of Chlorine and UV Irradiation during Wastewater Treatment

“…However, it is known that HO • is >5-fold the concentration of Cl • and thus contributes more to the disinfection efficiency [41]. The photodecay rates during the UV/chlorine AOP are related to the wavelength-dependent molar absorption coefficient [42]. The photodecay rate of chlorine has also been shown to increase with increasing pH at any wavelength.…”