Oxidation of aqueous organic pollutants using a stable copper nanoparticle suspension

Many applications of copper nanoparticles (Cu-NPs) have been suggested in recent years, although the potential for use of Cu-NPs in water treatment processes has received relatively little attention. This work highlights the preparation, characterization, and application of polyethylenimine capped copper nanoparticles for use in oxidative degradation of organic pollutants in aqueous solutions; atrazine was selected as a representative pollutant. A stable aqueous Cu-NP suspension was prepared, with polyethylenimine (PEI) as capping agent, under ambient conditions. The Cu:PEI ratio during Cu-NP synthesis has a significant influence on nanoparticle properties as well as on the degradation of atrazine. The synthesized Cu-NPs, which comprised a mixture of Cu-0 and Cu2O, induced rapid atrazine degradation (> 99 % in 1 h) and significantly superior performance over commercial nano-copper oxide powder. Mechanistic insight into the atrazine degradation, via electron spin resonance (ESR) measurements, demonstrated (i) that significant hydroxyl radicals were generated only in the presence of Cu-NPs, (ii) longevity of radical generation, and (iii) regeneration of hydroxide radicals. The efficiency of the Cu-NPs applied to oxidative degradation was further demonstrated on eight other representative organic water pollutants.