Highly efficient activation of sulfite by surface oxidized pyrite for atrazine degradation: Experimental and DFT study

Surface oxidized pyrite (SOPy-90) was synthesized via calcination and showed much higher catalytic ability for sulfite than the pristine pyrite to degrade atrazine (ATZ). The impacts of SOPy-90 dosage, sulfite doses, and dissolved O2 on the ATZ elimination by SOPy-90/sulfite system were studied. Furthermore, & beta;-FeOOH was generated on the surface of oxidized pyrite, which played a significant role in the catalysis of sulfite by SOPy-90. The reaction pH (4.0-7.0) was acidified to 4 by adding SOPy-90, which was beneficial for the sulfite activation by both material and dissolved Fe2+ to produce SO3 & BULL; . The generated SO3 & BULL; was further oxidized by dissolved O2 to form SO4 & BULL; as the predominant species, confirmed by the quenching experiments and EPR analysis. Besides, the Fe(II)/Fe(III) cycle was accelerated by the low-valent S( II) on the SOPy-90 surface, thus enhancing the SOPy-90 catalysis capacity. The density functional theory (DFT) calculations revealed that Fe(II) was more likely to activate HSO3  to generate SO3 & BULL; on the SOPy-90 surface. The SOPy-90/sulfite system has good reusability and showed excellent performance to decompose ATZ in real water treatment.

Automated summary

Surface oxidized pyrite (SOPy-90) synthesized by calcination displayed higher catalytic ability than pristine pyrite in degrading atrazine (ATZ) through sulfite. The effects of SOPy-90 dosage, sulfite doses, and dissolved O2 on ATZ elimination were investigated. Moreover, β-FeOOH was formed on the surface of oxidized pyrite, playing a significant role in the catalysis of sulfite by SOPy-90.