Sorbent-modified biodegradation studies of the biocidal cationic surfactant cetylpyridinium chloride.

Author(s) Timmer, N.; Gore, D.; Sanders, D.; Gouin, T.; Droge, S.T.J.
Journal Ecotoxicol Environ Saf
Date Published 2019 Oct 30
Abstract

Biodegradability studies for the cationic surfactant cetylpyridinium chloride (CPC) are hampered by inhibitory effects on inoculum at prescribed test concentrations (10-20 mg organic carbon/L). In this study, we used C labeled CPC in the 28 d Headspace Test (OECD 310) and demonstrated that CPC was readily biodegradable (10->60% mineralization within a 10 day window) at test concentrations 0.006-0.3 mg/L with CPC as single substrate. Biodegradation efficiency was comparable over this concentration range. CPC inhibited degradation at 1 mg/L and completely suppressed inoculum activity at 3 mg/L. In an extensive sorbent modified biodegradation study we evaluated the balance between CPC bioaccessibility and toxicity. A non-inhibitory concentration of 0.1 mg/L CPC was readily biodegradable with 83% sorbed to SiO, while biodegradation was slower when 96% was sorbed. SiO mitigated inhibitory effects of 1 mg/L CPC, reaching >60% biodegradation within 28 d; inhibitory effects were also mitigated by addition of commercial clay powder (illite) but this was primarily reflected by a reduced lag phase. At 10 mg/L CPC SiO was still able to mitigate inhibitory effects, but bioaccessibility seemed limited as only 20% biodegradation was reached. Illite limited bioaccessibility more strongly and was not able to sustain biodegradation at 10 mg/L CPC.

DOI 10.1016/j.ecoenv.2019.109417
ISSN 1090-2414
Citation Timmer N, Gore D, Sanders D, Gouin T, Droge ST. Sorbent-modified biodegradation studies of the biocidal cationic surfactant cetylpyridinium chloride. Ecotoxicol Environ Saf. 2019;182:109417.

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