Abstract
In the present study, we demonstrated that the presence of cysteine could remarkably enhance the degradation of atrazine by Fe(3)O(4)/persulfate system. The results of electron paramagnetic resonance (EPR) spectra confirmed the combination of cysteine and Fe(3)O(4) exhibited much higher activity on activation of persulfate to generate more SO(4)(•-) and •OH than Fe(3)O(4) alone. At pH of 3.0, SO(4)(•-) and •OH contributed to about 58.2 % and 41.8 % of atrazine removal respectively, while •OH gradually dominated the oxidation of atrazine from neutral condition to alkaline condition. The co-existing Cl(-) and HCO(3)(-) could quench SO(4)(•-), resulting in the inhibition of atrazine degradation. The presence of low natural organic matters (NOM) concentration (0-2 mg L(-1)) could enhance the atrazine removal, and high concentration (>5 mg L(-1)) of NOM restrained the atrazine degradation. During the Cysteine/Fe(3)O(4)/Persulfate process, cysteine served as a complexing reagent and reductant. Through acidolysis and complexation, Fe(3)O(4) could release dissolved and surface bound Fe(2+), both of which contributed to the activation of persulfate together. Meanwhile, cysteine was not rapidly consumed due to a regeneration process, which was beneficial for maintaining Fe(2+)/Fe(3+) cycle and constantly accelerating the activation of persulfate for atrazine degradation. The reused Fe(3)O(4) and cysteine in the Cysteine/Fe(3)O(4)/Persulfate process exhibited high stability for the atrazine degradation after three cycles. The degradation pathway of atrazine included alkylic-oxidation, dealkylation, dechlorination-hydroxylation processes. The present study indicates the novel Cysteine/Fe(3)O(4)/Persulfate process might be a high potential for treatment of organic polluted water.