Technical development of UV-C- and VUV-photochemically induced oxidative degradation processes

Abstract

Technical development work is presented, where the VUV photochemically induced oxidative degradation is used: (i) for analytic purposes, and (ii) for small to medium scale (< 10 m2/d) waste water treatment processes or ultrapure water production. In the first case, small Xe-excimer radiation sources with an integrated reaction space designed for optimal conditions, as far as incident photon flux density, turbulence and concentration of dissolved molecular oxygen are concerned, have been built and tested. Under conditions of exhaustive oxidation and/or mineralization of pollutants in a continuous regime, they may be used for sample pre-treatment modules prior TOC, TOX and electrochemical trace metal analysis. Under conditions of partial oxidation or mineralization, the same lamp/reactor combination may be used for functionalization purposes prior to e.g. GC or HPLC analyses. In the second case, mass transfer limitations between the non-irradiated bulk volume and the irradiated volume are overcome by the electrochemical generation of molecular oxygen within or close to the irradiated volume and by the design of the photochemical part of the reactor.

UV-based advanced oxidation processes for the treatment of odour compounds: Efficiency and by-product formation

“…This restricts the VUV irradiation to thin-film irradiation systems which are not economic for large-scale drinking water treatment plants and cause high capital costs. Other potential applications besides small-scale drinking water treatment systems for VUV irradiation or VUV/O 3 are the production of ultrapure water or analytical purposes (Braun et al, 2004). For this reason, the EE/O value is not qualified for the supply of data for the scale-up of the VUV advanced oxidation process.…”

Photochemical decomposition of perfluorooctanoic acid in aqueous periodate with VUV and UV light irradiation

“…In VUV systems, water photolyzes into • OH, hydrogen radicals (H • ) and aquated electrons (e aq − ) upon light excitation [20], result- ing in IO 4 − almost being scavenged by aquated electron (Eqs. (1) and (2)) [21] in VUV/NaIO 4 system.…”

Online TOC Analysis Based on Reagent-free Oxidation of Dissolved Organic Matter Using a Mercury Lamp-Pass-Through Photoreactor

“…12,[14][15][16]18 However, Xe-excimer lamps require high-frequency and high-voltage power supplies, which increase the costs and raise the necessary safety management levels. In some cases, rapid mineralization of the DOM requires additional oxygen gas because the The reagent-free mineralization of dissolved organic matter (DOM) in river water was achieved within 1 min using a lamp-pass-through photoreactor containing a narrow reaction tube (2 mm i.d.)…”

“…thickness of the portion of the solution in which • OH and the radicalized intermediates are produced is too low to react with the oxygen that is naturally present in a bulk solution as a result of the extremely strong absorption of 172 nm light. 15,16,18 Furthermore, for all VUV photoreactors, the decomposition efficiency of the DOM decreases in the presence of coexisting substances that absorb the VUV light and scavenge…”