title: Formation of Chlorination Byproducts and Their Emission Pathways in Chlorine Mediated Electro-Oxidation of Urine on Active and Nonactive Type Anodes.
abstract: Chlorination byproducts (CBPs) are harmful to human health and the environment. Their formation in chlorine mediated electro-oxidation is a concern for electrochemical urine treatment. We investigated the formation of chlorate, perchlorate, and organic chlorination byproducts (OCBPs) during galvanostatic (10, 15, 20 mA · cm(-2)) electro-oxidation of urine on boron-doped diamond (BDD) and thermally decomposed iridium oxide film (TDIROF) anodes. In the beginning of the batch experiments, the production of perchlorate was prevented by competing active chlorine and chlorate formation as well as by direct oxidation of organic substances. Perchlorate was only formed at higher specific charges (>17 Ah · L(-1) on BDD and >29 Ah · L(-1) on TDIROF) resulting in chlorate and perchlorate being the dominant CBPs (>90% of initial chloride). BDD produced mainly short chained OCBPs (dichloromethane, trichloromethane, and tetrachloromethane), whereas longer chained OCBPs (1,2-dichloropropane and 1,2-dichloroethane) were more frequently found on TDIROF. The OCBPs were primarily eliminated by electrochemical stripping: On BDD, this pathway accounted for 40% (dichloromethane) to 100% (tetrachloromethane) and on TDIROF for 90% (1,2-dichloroethane) to 100% (trichloromethane) of what was produced. A post-treatment of the liquid as well as the gas phase should be foreseen if CBP formation cannot be prevented by eliminating chloride or organic substances in a pretreatment.
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Hanspeter
authors.initials: H
authors.lastname: Zöllig
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Annette
authors.initials: A
authors.lastname: Remmele
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Cristina
authors.initials: C
authors.lastname: Fritzsche
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Morgenroth
authors.affiliation: Eawag, Swiss Federal Institute of Aquatic Science and Technology, Überlandstrasse 133, 8600 Dübendorf, Switzerland.
authors.forename: Kai M
authors.initials: KM
authors.lastname: Udert
mesh_terms: D001895:Boron / Q000737:chemistry; D002704:Chlorates / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D002713:Chlorine; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D005025:Ethylene Dichlorides / Q000737:chemistry; D054879:Halogenation; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000737:chemistry*; D007495:Iridium / Q000737:chemistry; D010084:Oxidation-Reduction; D010472:Perchlorates / Q000737:chemistry; D014556:Urine / Q000737:chemistry*
chemical_list: D002704:Chlorates; D002712:Chlorides; D005025:Ethylene Dichlorides; D006843:Hydrocarbons, Chlorinated; D010472:Perchlorates; C044458:iridium oxide; D007495:Iridium; D002713:Chlorine; C024565:ethylene dichloride; D001895:Boron; C494474:perchlorate