KrCl and XeCl excilamps and LP-Hg lamp for UV and UV/H₂O₂decolourization of dyes in water

Abstract

In the present study, the decolourization efficiencies of LP-Hg lamp, XeCl and KrCl excilamps at the same power density were compared for the decolourization of dyes in water by UV and UV/HO processes in a batch reactor. Laboratory prototypes of XeCl and KrCl excilamps and a commercial LP-Hg lamp were studied as UV sources. Methylene Blue and Eliamine Blue dyes were used as model pollutants. The effect of the initial concentrations of dye and HO in the TOC removal and kinetic parameters were also studied. The ratio of dye decolourization to the electric power consumption of the KrCl excilamp and LP-Hg lamp for the decolourization of Methylene Blue and Eliamine Blue were evaluated. As a result, the KrCl excilamp showed significantly higher decolourization efficiencies than LP-Hg lamp and XeCl excilamp, but the dye removal rate was significantly slower for Methylene Blue than for Eliamine Blue with this lamp. The KrCl lamp can be an alternative to conventional LP-Hg lamp for the decolourization of dyes by photodegradation, but it depends on the type of dye treated. The addition of HO in a concentration between 0.05 and 0.09%v/v increases significantly the efficiency of the decolourization of Methylene Blue, and further increase does not lead to a higher increase in conversion. The experimental data were fitted to the one phase decay kinetic model with good agreement and the kinetic parameters were reported.

Adsorption of Cadmium Using Biochars Produced from Agro-Residues

“…BET surface areas were estimated from nitrogen adsorption, and desorption isotherms were performed at 77 K in a surface area and pore size analyzer (Nova2200e, Quantachrome Instruments). The biochar samples were previously degassed at 120 °C for 5 h. Methylene blue adsorption measurements were used for a more accurate determination of the surface area for liquid adsorption applications. , The morphology of biochars was analyzed through SEM (JEOL JSM-6490LV). The elemental composition of the biochar samples was analyzed by an X-EDX-ray microprobe (INCA PentaFETx3 Oxford Instruments).…”

Recent Achievements in Dyes Removal Focused on Advanced Oxidation Processes Integrated with Biological Methods

“…Measurements of cytotoxicity, mutagenicity and phytotoxicity changes, proposal of degradation mechanism, comparison of different UV sources [80][81][82][83][84][85] Photocatalytic oxidation Synthesizing nanoparticles, efficient under visible light or difunctional catalysts, green methods of catalyst synthesis [86][87][88][89][90][91]…”

Enhanced Direct Photolysis of Organic Micropollutants by Far-UVC Light at 222 nm from KrCl* Excilamps

“…KrCl* excilamps are also promising to be applied in advanced oxidation processes (AOPs) to remove organic micropollutants (OMPs) in water, due to increased formation of reactive oxygen species from common oxidants at 222 nm. − Enhanced AOP by KrCl* excilamps with hydrogen peroxide (H 2 O 2 ) has been reported for monochlorophenols, ,, 4-chlorobenzoic acid, ceftriaxone, dyes (e.g., methylene blue, , eliamine blue, and Congo red), and linear alkylbenzenesulfonate . The molar absorption coefficient (ε) of H 2 O 2 at 222 nm (ε 222 = 99 M –1 ·cm –1 ) is 5.4 times higher than that at 254 nm (ε 254 = 18.5 M –1 ·cm –1 ), while the quantum yield (Φ) is similar at the two wavelengths (Φ 222 = 1.1 ± 0.1; Φ 254 = 1.15 ± 0.05).…”

“…Hence, the fluence-normalized steady-state concentration of hydroxyl radical by KrCl* excilamps was reported to be 9.4 times higher than that by LPUV. 17 Therefore, the AOP with H 2 O 2 at 222 nm increased the degradation of 4-chlorobenzoic acid 17 and methylene blue 19 by 9 and 3 folds, respectively, compared to LPUV/H 2 O 2 at similar conditions. KrCl* excilamps also enhanced AOP with persulfate.…”