Flow-Through Electrochemical Activation of Persulfate for Efficient Wastewater Treatment using Ti₄O₇ Reactive Electrochemical Membranes

Abstract

Herein, a flow-through reactive electrochemical membrane (REM) system was reported for the complete activation of S 2 O 8 2− upon a single-pass through the Ti 4 O 7 REM cathode with less than 10 s of residence time. The kinetic constant for S 2 O 8 2− activation was observed at 21−109 × 10 −5 m s −1 , which is 1−2 orders of magnitude higher than the reported conventional batch/ flow-by electrochemical systems even with the addition of activators. The Ti 4 O 7 REM electrode exhibited good stability in activating S 2 O 8 2−, and the efficiency decreased by only ∼5% after 5 h of continuous operation due to scaling in a wastewater treatment plant (WWTP) effluent sample. As a proof-of-concept, the REM−persulfate system, i.e., integration of both anodic electrooxidation and cathodic persulfate-based advanced oxidation process, was successfully applied to treat both antibiotics-spiked WWTP effluent and reverse osmosis (RO) concentrate of pretreated coking wastewater. A single-pass of the REM−persulfate system achieved over 95% removal of 6 antibiotics (each 10 μg L −1 ) from WWTP effluents. As compared with the REM system without persulfate, the addition of 10 mM S 2 O 8 2− for treating RO concentrate of pretreated coking wastewater resulted in a significant increase in total organic carbon removal from 51.5 to 78.9%. However, it also resulted in the formation of chlorinated byproducts, including ClO 3 − , ClO 4 − , and absorbable organic chlorine. Techno-economic analysis with an RO concentrate of pretreated coking wastewater showed that the REM−persulfate system featured a 50% lower initial capital cost than the REM system without persulfate. Results of this study indicate the REM−persulfate system may be potentially a promising wastewater treatment technology.

Mxene-Cu Electrified Membranes with Confined Lamellar Channels for the Flow-through Electrochemical Reduction of Nitrate to Ammonia

“…Significantly, as separation devices, EMs are inherently very rich in permeation channels, such as nanofluidic or microfluidic ones, which are well suited to improve the mass transport of reactants in a flow-through mode. Meanwhile, different from common flow-through electrodes with unimpeded pathways, − the channels in EMs are relatively narrow and confined, which would not only better increase the opportunity for contact between the permeable substances and the electrode materials but also regulate the residence time of reactants in the electrodes; thus, it is good for the electrochemical reactions within the EMs. − Also, from another perspective, the unique retention function of EMs could serve to protect the catalytic centers especially those inside the membrane electrodes from interference by other species, − which will be extremely beneficial for maintaining the catalytic performance of electrodes in complex environments. Thus, the use of EMs as flow-through electrodes could emerge as a promising alternative to overcome the limitations of conventional electrocatalysts.…”