Heterogeneous degradation of toxic organic pollutants by hydrophobic copper Schiff-base complex under visible irradiation

A hydrophobic complex of Cu2+[bis-salicylic aldehyde-o-phenylenediamine],Cu-SPA,was prepared and used as a heterogeneous photocatalyst to degrade organic pollutants in water under visible irradiation(420 nm)at neutral pH.The structure of complex was characterized by using nuclear magnetic resonance(NMR),elemental analysis,IR and UV-vis spectrometries.Degradation of Rhodamine B(RhB),Sulforhodamine B(SRB)and Benzoic acid(BA)in water were used as model reactions to evaluate the photocatalytic activities of Cu-SPA.The results indicated that RhB and SRB were easily adsorbed on the hydrophobic surface of Cu-SPA from aqueous solution(the maximum adsorption amount:Qmax=11.09 and 8.05μmol/g,respectively).Under visible irradiation,RhB and SRB were decolorized completely after 210 and 240 min,respectively,and BA was removed completely after 5 h.The efficiency of H2O2was>95%,in contrast to that of the reaction without catalyst or light(<20%).In water soluble medium,the hydrophobic Cu-SPA can be used more than 6 cycles.ESR results and the behavior of cyclic voltammetry showed that,in the reaction process,Cu2+-SPA was reduced to intermediate state Cu+-SPA firstly,which was extremely unstable and reacted rapidly with H2O2,leading to high reactive oxygen species(·OH radical)to degrade the substrate.

A hydrophobic complex of Cu2＋[bis-salicylic aldehyde-o-phenylenediamine], Cu-SPA, was prepared and used as a heterogeneous photocatalyst to degrade organic pollutants in water under visible irradiation （λ≥420 nm） at neutral pH. The structure of complex was characterized by using nuclear magnetic resonance （NMR）, elemental analysis, IR and UV-vis spectrometries. Degradation of Rhodamine B （RhB）, Sulforhodamine B （SRB） and Benzoic acid （BA） in water were used as model reactions to evaluate the photocatalytic activities of Cu-SPA. The results indicated that RhB and SRB were easily adsorbed on the hydrophobic surface of Cu-SPA from aqueous solution （the maximum adsorption amount： Qmax = 11.09 and 8.05 μmol/g, respectively）. Under visible irradiation, RhB and SRB were decolorized completely after 210 and 240 min, respectively, and BA was removed completely after 5 h. The efficiency of H202 was 〉 95%, in contrast to that of the reaction without catalyst or light （〈 20%）. In water soluble medium, the hydrophobic Cu-SPA can be used more than 6 cycles. ESR results and the behavior of cy- clic voltammetry showed that, in the reaction process, Cu2＋-SPA was reduced to intermediate state Cu＋-SPA firstly, which was extremely unstable and reacted rapidly with H2O2, leading to high reactive oxygen species （.OH radical ） to degrade the substrate.