Degradation of pyrene in cetylpyridinium chloride-aided soil washing wastewater by pyrite Fenton reaction

• Both pyrene and CPC were effectively degraded in 180 min by pyrite Fenton reaction.
• Iron was dissolved continuously and reacted with H2O2 to produce OH.
• CPC was degraded to CO2 and ammonium as main degradation products.
• No oxy-pyrenes were accumulated during pyrene degradation in pyrite Fenton system.

Degradation of pyrene by pyrite Fenton reaction in synthetic cetylpyridinium chloride (CPC)-aided soil washing wastewater (SWW) was investigated in a closed batch reactor. Pyrene in the presence of CPC was gradually degraded in the pyrite Fenton system by 96% in 180 min at initial pH 7 showing pseudo-first-order reaction kinetics (0.0194 min−1), while the concentration of pyrene in the absence of CPC decreased abruptly by 91% in 5 min and then did not significantly decrease by the end of sampling time (180 min). In a classic Fenton system, pyrene in the presence of CPC was degraded by 35% in 180 min at initial pH 3. The sustainable reactivity of pyrite Fenton was attributed to slow but continuous dissolution of Fe(II) from the pyrite surface leading to continuous production of reactive radicals during the reaction. Pyrene in the presence of CPC was mainly degraded by OH radicals. Its product study showed that the pyrite Fenton system can successfully degrade pyrene in the CPC-aided SWW without accumulating toxic oxy-pyrenes such as 1,6-pyrenequinone and 1,8-pyrenequinone. CPC was also successfully degraded (95%) in the pyrite Fenton system, forming carbon dioxide and ammonium as main degradation products.