Remediation of hexachlorocyclohexanes by electrochemically activated persulfates

Wacławek, Stanisław; Antoš, Vojtech; Hrabák, Pavel; Černík, Miroslav; Elliott, Daniel

Remediation of hexachlorocyclohexanes by electrochemically activated persulfates

2016

Wacławek, Stanisław | Antoš, Vojtech | Hrabák, Pavel | Černík, Miroslav | Elliott, Daniel

Hexachlorocyclohexane (HCH) isomers represent a family of formerly widely utilized pesticides that are persistent, capable of undergoing long-range transport and tend to bioaccumulate in human and animal tissue. Their widespread global utilization coupled with a propensity to adversely impact human health and the environment translates into an urgent need to develop feasible methodologies by which to treat HCH-impacted groundwater and soil. The present study was conducted to evaluate the efficacy of two persulfate-based oxidants: peroxydisulfate (S₂O₈ ²⁻, PDS) and peroxymonosulfate (HSO₅ ⁻, PMS) activated by electrochemical processes (EC) to treat HCH-impacted environmental media. This research demonstrated that the optimal experimental conditions (oxidant dose and electrical current) were 2 mM PDS and 20 mA for an aqueous solution of 4 μM of summed HCHs (ΣHCH). GC/MS full scan analysis revealed the presence of 2,4,6–trichlorophenol as the only detectable intermediate formed during electro-activated PDS treatment of ΣHCH. The investigated method was tested on leachate from a known HCHs-impacted site in Hajek, Czech Republic which contained 106 μg/l of ΣHCH and 129 μg/l of chlorobenzenes. Results from batch treatment showed positive results for electro-activated PDS but only negligible effectiveness for electro-activated PMS. In addition to explaining the efficacy of the electro-activated PDS, this research also explored the basis for the differing reactivities of these two persulfates.

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