Removal of perfluorooctanoic acid in simulated and natural waters with different electrode materials by electrocoagulation

Abstract

Increasing attentions have been paid on widespread perfluorooctanoic acid (PFOA) contaminations in the environment globally, especially in the industrial wastewaters and natural water bodies. In order to perform the treatment of PFOA simulated solution effectively with periodically reverse electrocoagulation (PREC), intensive studies were implemented on the conditions of treatment and adsorption mechanism. The optimal conversion rate of 1 mg L−1 PFOA treatment could be achieved 99.6% with Al-Zn electrode, when the voltage and stirring speed were set to 9 V and 500 rmp. The energy consumption of treating PFOA simulated aqueous solution at 20 min using Al-Zn electrodes was 43.93 kWh kg−1. In addition, the PREC technique was further applied to eliminate the PFOA contaminations in the natural groundwater, generating the conversion rate up to 79.4% at 60 min. Moreover, it was verified that PFOA contamination was adsorbed on the flocs of Zn0.61Al0.39(OH)2(CO3)0.195·xH2O by the detection of X-ray diffraction spectra (XRD) and Fourier transform infrared (FTIR) spectrum, the mainly mechanism was adsorption bringing and enmeshment, primarily resulting from the hydrophobic interaction of PFOA and Al-Zn hydroxide flocs.