Degradation of acrylic copolymers by Fenton’s reagent Carsten Mai a, *, Andrzej Majcherczyk b , Wiebke Schormann b ,AloysHu¨ttermann b a Institute of Wood Biology and Wood Technology, Bu ¨sgenweg 4, 37077 Go ¨ttingen, Germany b Institute of Forest Botany, University of Go ¨ttingen, Bu ¨sgenweg 2, 37077 Go ¨ttingen, Germany Received 17 May 2001; received in revised form 25 July 2001; accepted 4 August 2001 Abstract The degradation of different copolymers of acrylamide and acrylic acid by Fenton’s reagent was studied. The polymers tested were either homopolymers or copolymers containing lignin sulfonate, guaiacol or 3,4-dihydroxylbenzoic acid, respectively. Acryl- amidecopolymers(PAAm)weredegradedfasterthanpolymersofacrylicacid(PAA).AmongthePAAm,thecopolymersoflignin sulfonateandguaiacolweredegradedatasignificantlyhigherratethanthecorrespondinghomopolymer,whereasamongthePAA, therateofdegradationwashighestwithcopolymersofguaiacoland3,4-dihydroxylbenzoicacid.ThedecreaseofH 2 O 2 ,i.e.therate ofhydroxylradicalproductioninthepresenceofacertainpolymer,didnotcorrelatewiththerateofitsdegradation.Itwascon- cluded that the incorporation of lignin and certain phenolic compounds into an acrylic chain may accelerate the decay of these polymers by wood decaying fungi, which reportedly produce hydroxyl radicals extra-cellularly, and through the use of advanced oxidation systems applied in sewage cleaning. # 2001ElsevierScienceLtd.Allrightsreserved. Keywords: Fenton’s reagent; Lignin copolymer; Acrylic; Degradation 1. Introduction Water soluble, poly(acrylic acid) and polyacrylamide are highly resistant to biodegradation. One method of enhancing the degradability of such non-hydrolyzable macromolecules entails grafting components which are readily degradable into the main polymer backbone. Several attempts have been made in which some natu- rally occurring polymers of plant or microbial origin, such as lignin [1–13], starch [14], cellulose [15], and poly(hydroxylbutyric acid) [16] were introduced into a synthetic polymer structure. The naturally occurring fractions of the resulting products have shown appre- ciable biodegradibility. The main property of macromolecules which compli- cates biodegradation by microorganisms is their high molecular weight. It prevents the passage of the poly- mers through the plasma membrane of microbial cells so that a preceding extra-cellular reduction to small pieces prior to intra-cellular mineralization is necessary. This extra-cellular degradation step can be brought about by extra-cellular enzymes or chemically, e.g. by reducedoxygenspecies,suchashydroxylradicals. In the present study, the decomposition of acrylic copolymerswhichcontainligninsulfonateorlignin-like monomeric phenolics by Fenton’s reagent was investi- gated.Thehydroxylradicalpossessesanextremelyhigh redox potential for the one-electron reduction to water [17]: HO  þ H þ þ e  ! H 2 O E 0 ¼þ2180 mV Any oxidant with a higher redox potential would react with water forming hydroxyl radicals. For this reason, the hydroxyl radical is the strongest oxidant in biological systems. It has been suggested that hydroxyl radicals are involved in the degradation of both lignin (by white-rot fungi) and cellulose (by brown-rot fungi). The degradation of 14 C-labeled lignin by UV/H 2 O 2 , Fenton’s reagent, photosensitized rivoflavin as well as byUV-and g-irradiation has been previously described [18]. Both 14 C-methoxy labeled lignin and ring- and side-chain lignins were extensively degraded by both photosensitized rivoflavin and UV/H 2 O 2 . A rapid, nearly complete degradation was observed with Fenton’s reagent. 0141-3910/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII:S0141-3910(01)00209-9 Polymer Degradation and Stability 75 (2002) 107–112 www.elsevier.com/locate/polydegstab * Corresponding author. Tel.: +49-551-393484; fax: +49-551- 392705. E-mail address: cmai@gwdg.de (C. Mai).