Reactive Blue 19 dye removal by UV-LED/chlorine advanced oxidation process.

In recent years, advanced oxidation processes (AOPs) have indicated the greatest potential in the removal of stable organic compounds, including dyes. In this study, the ultraviolet light-emitting diodes (UV-LEDs) combined with chlorine was evaluated to remove Reactive Blue 19 (RB19) dye from aqueous solution. The effect of key experimental parameters including pH, initial chlorine concentration, initial dye concentration, and reaction time on the performance of UV-LED irradiation, UV-LED/chlorine, and the chlorination method for the removal of RB19 was studied in this research. Results showed that, more than 99% of RB19 was removed after 30 min of reaction time under optimized conditions (pH = 5, [chlorine] = 300 µM, and [RB19] = 20 mg L-1) with apparent kinetic rate constant (kapp) of 17.1 × 10-2 min-1 in UV-LED/chlorine process. However, for the chlorination method, removal efficiency was 64.7% (kapp = 3.41 × 10-2 min-1) with an apparent kinetic rate constant of 0.0341 min-1. Results also showed that UV-LED irradiation is not effective at all in removing RB19. The scavenging assay showed that OH• radicals (67.23%) had the highest contribution in RB19 removal in UV-LED/chlorine process while Cl• (17.82%) and [Formula: see text] (8.56%) had a minor role in the degradation of the dye. The RB19 degradation kinetics analysis revealed that the processes of UV-LED/chlorine and chlorination degradation followed the pseudo-first-order kinetic model. In this study, the impact of chloride, nitrate, bicarbonate, carbonate, sulfate, and sulfite anions on the performance of the process was investigated. It indicated that sulfite anion has the most negative impact on the RB19 removal process. By evaluating the synergistic effect between UV-LED lamp and chlorine, a synergy index of 5.0 was obtained for the UV-LED/chlorine process. The results presented that the UV-LED/chlorine process has a better performance than each of them alone and has the necessary efficiency for RB19 removal. Measuring COD reported its removal efficiency of 98% during the UV-LED/chlorine process under optimized conditions. Experiments continued with textile factory wastewater and indicated 30.9% of its COD removed after treatment when 1.0 µM chlorine was used.

Effect of phenytoin on retinal ganglion cells in acute isolated optic neuritis.

OBJECTIVE: Phenytoin has been shown to reduce the peripapillary retinal nerve fiber layer (pRNFL) loss in optic neuritis (ON). We evaluated the effects of phenytoin on retinal ganglion layers and visual outcomes of newly diagnosed acute ON. METHODS: A randomized, placebo-controlled trial was conducted in a tertiary referral eye hospital and patients with the first episode of typical demyelinating ON, without any history of multiple sclerosis were randomly assigned to phenytoin or placebo. The thickness of ganglion cell-inner plexiform layer (GCIPL) measured by optical coherence tomography (OCT) was considered as the primary outcome. RESULTS: One patient in the phenytoin group developed severe cutaneous rashes that progressed to Stevens-Johnson syndrome (SJS)/toxic epidermal necrosis (TEN), and further allocation of patients to the phenytoin group was stopped, and finally fifteen participants were included in the phenytoin group. Fifty-one patients were enrolled to the placebo group, from which four were excluded. Both visual acuity and field were not significantly different between the control and phenytoin groups after 1 and 6 months. Mean 3- and 6-mm macular GCIPL thicknesses decreased after 6 months to 73.6 ± 14.1 and 57.9 ± 7.5 µm, respectively, in the phenytoin group and to 71.6 ± 15.7 and 55.6 ± 6.6 µm, respectively, in the placebo group with no significant differences between the two groups (P = 0.77 and P = 0.26, respectively, linear multilevel model). CONCLUSION: Phenytoin is not probably safe and effective as neuroprotection after acute ON. Further investigation with other sodium channel inhibitors could be considered.