Remediation of soil contaminated with PAHs and γ-HCH using Fenton oxidation activated by carboxymethyl cellulose-modified iron oxide-biochar

The remediation of soil contaminated with hydrophobic organic pollutants has attracted great public concern. In the present study, a novel catalyst using biochar supported ferro ferric oxide modified by carboxymethyl cellulose (CMC-Fe 3 O 4 /BC) was developed to activate the Fenton reaction for hazardous hydrophobic organic pollutants , and the degradation mechanisms were analyzed in terms of free radicals , electron transfer pathways and degradation intermediates. The results showed that the CMC-Fe 3 O 4 /BC-activated H 2 O 2 system degraded nearly 100% of pyrene in the aqueous system after a 1440-min reaction. The catalyst was also applied to remediate industrial field soil contaminated with PAHs and γ-HCH. The removal rate of the total pollutants reached 61.1% after a 10-day reaction, which was higher than that of Fe 3 O 4 /BC without modification. CMC enabled the Fe 3 O 4 particles to more equably distribute on the BC surface, further effectively activating H 2 O 2 to generate more ⋅OH and forming different degradation products compared to the Fe 3 O 4 /BC. Additionally, the CMC-Fe 3 O 4 /BC-activated H 2 O 2 system obviously enhanced electron transfer on the BC surface. Thus, the PAHs and γ-HCH could be degraded via electron transfer pathways.