title: Engineering of a highly efficient Xe₂*-excilamp (xenon excimer lamp, λmax=172 nm, η=40%) and qualitative comparison to a low-pressure mercury lamp (LP-Hg, λ=185/254 nm) for water purification.
abstract: Excilamps are mercury-free gas-discharge sources of non-coherent VUV or UV radiation with high radiant power and a long lifetime. The most efficient excilamp that is currently available on the market is a VUV xenon excilamp system (Xe2(*)-excimer lamp, λ(max) = 172 nm) with a stated radiant efficiency η of 40% at an electrical input power P(el) of 20 W, 50 W or 100 W. In this paper, the use of this highly efficient Xe2(*)-excilamp (P(el) = 20 W) for water treatment is demonstrated using a recirculating laboratory photoreactor system with negative radiation geometry. The efficiency in the 172 nm initiated bleaching of aqueous solutions of Rhodamine B is compared to that initiated by a common low-pressure mercury (LP-Hg) lamp (185 nm, TNN 15/32). The dependence of the pseudo zero order rate constant k´ of decolorization of RhB on the flow rate and on the initial concentration of RhB was investigated. Both lamps exhibited dependences of k´ on the initial concentration of RhB, which represents a typical saturation kinetical behavior. The saturation kinetics was very prominent in the case of the Xe2(*)-excilamp. Also, the Xe2(*)-excilamp treatment exhibited a significant influence on the flow rate of the RhB aqueous solution, which was not the case during the LP-Hg lamp initiated bleaching of RhB. The results of this paper demonstrate that Xe2(*)-excilamps can be used for VUV-initiated water purification. However, to reach the maximum efficacy of the Xe2(*)-excilamp for photo-initiated water purification further engineering optimization of the photoreactor concept is necessary.
authors.affiliation: German Jordanian University, Chemical-Pharmaceutical Engineering Department, School of Applied Medical Sciences, 35247, Amman, 11180, Jordan. Electronic address: samer.gharabli@gju.edu.jo.
authors.forename: Samer
authors.initials: S
authors.lastname: Al-Gharabli
authors.affiliation: Hochschule Furtwangen University, Campus Villingen-Schwenningen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany.
authors.forename: Patrick
authors.initials: P
authors.lastname: Engeßer
authors.affiliation: Hochschule Furtwangen University, Campus Villingen-Schwenningen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany.
authors.forename: Diana
authors.initials: D
authors.lastname: Gera
authors.affiliation: Hochschule Furtwangen University, Campus Villingen-Schwenningen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Klein
authors.affiliation: Hochschule Furtwangen University, Campus Villingen-Schwenningen, Jakob-Kienzle-Str. 17, 78054 Villingen-Schwenningen, Germany. Electronic address: op@hs-furtwangen.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Oppenländer
mesh_terms: D019281:Dimerization; D004738:Engineering; D008628:Mercury; D055668:Photochemical Processes; D011312:Pressure; D055618:Radiation Equipment and Supplies; D012235:Rhodamines / Q000737:chemistry / Q000302:isolation & purification; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry; D018508:Water Purification / Q000295:instrumentation*; D014978:Xenon / Q000737:chemistry*
chemical_list: D012235:Rhodamines; D014867:Water; D014978:Xenon; D008628:Mercury; C029773:rhodamine B
keywords: 172 nm; AOP; Excilamp; Rhodamine B; Xenon-excimer lamp