Oxidative degradation of Triton X-45 using zero valent aluminum in the presence of hydrogen peroxide, persulfate and peroxymonosulfate

Abstract

Nanoscale zero-valent aluminum (nZVAl)-activated hydrogen peroxide (HP), persulfate (PS) and peroxymonosulfate (PMS) oxidation of Triton™ X-45 (TX-45), an octylphenol polyethoxylate, was investigated. Treatment performances were evaluated in distilled water (DW), raw surface water (SW), tap water (TW) and effluent from a domestic wastewater treatment plant (WW). Two different acute toxicity tests using Vibrio fischeri and Pseudokirchneriella subcapitata as well as the UMU-Chromo genotoxity test were undertaken to evaluate the ecotoxicological effects of TX-45 and its oxidation products. Poor TX-45 removals in the absence of nZVAl (mere HP, PS and PMS treatments) and oxidants (nZVAl/O2/H+ treatment) were obtained (5%-38%). Activation of HP, PS and PMS with nZVAl substantially enhanced TX-45 degradation. Complete TX-45 degradation occurred in DW with the nZVAl/PS and nZVAl/PMS treatment combinations after 90min and 60min, respectively, whereas only 76% TX-45 removal was obtained with nZVAl/HP after 120min (TX–45=2mg/L; nZVAl=1g/L; HP-PMS=0.25mM; PS=0.5mM; pH=3). In DW, the decreasing order of TX-45 removal efficiencies was obtained as follows; nZVAl/PMS≈nZVAl/PS>nZVAl/HP and as nZVAl/PMS>nZVAl/HP>nZVAl/PS in SW and WW. The nZVAl/PS-treated TX-45 samples did not exhibit toxic effects on V. fischeri; the relative inhibition increased from 15% to 26% in DW and decreased to practically non-toxic levels (<8%) in SW after 120min treatment. During the early stages of nZVAl/PS treatment, P. subcapitata toxicity of TX-45 increased from 35% to 44% and from 39% to 52% in DW and SW samples, respectively. After 120min treatment, it dropped back to 40% and 25% in DW and SW samples, respectively. The original and nZVAl/PS-treated TX-45 neither exhibited cytotoxic nor genotoxic effects.