Photoelectrocatalytic advanced oxidation of perfluoroalkyl substances in groundwaters of the Veneto Region, Italy
Alessandro Pietro Tucci, Sapia Murgolo, Cristina De Ceglie, G. Máscolo, Massimo Carmagnani, Paolo Ronco, Massimiliano Bestetti, Silvia Franz
Abstract
Photoelectrocatalysis (PEC) was applied for the degradation of PFASs in natural groundwater collected from two wells located in the Veneto Region (Italy) where a massive contamination of the aquifer was discovered. Out of 48 monitored species, up to 9 PFASs were detected. On average, the degradation rate followed the order: PFOA>PFHpA>PFHxA≈PFPeA>PFBA and PFOS>PFHpS; the concentration of PFBS and PFHxS did not change during the tests. The overall PFASs concentration decreased by 63 % in well 1 and by 65 % in well 2. PEC tests of PFOA solutions ([PFOA] = 2 μg/l; [K 2 SO 4 ] = 4 mM] induced the transient formation of PFHpA, followed by PFHxA, PFPeA and PFBA, confirming the reaction pathway consisting of decarboxylation followed by a stepwise losing of CF 2 units, transiently forming shorter chain intermediates. PEC efficiency was compared to photolysis. According to electrical energy per order of magnitude, PEC outperforms conventional photolysis and most of the other advanced oxidation processes reported in literature. • PFAS-contaminated groundwater of the Veneto Region was successfully treated by PEC. • The overall PFAS removal was 63 % in well 1 and 65 % in well 2. • The degradation rate was in the order: PFOA>PFHpA>PFHxA≈PFPeA>PFBA; PFOS>PFHpS. • Reaction pathway involves decarboxylation followed by a stepwise loss of CF2 units. • Based on EEO, PEC energy costs are comparable to or lower than those of known AOPs.