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  • Modeling electrochemical oxidation and reduction of sulfamethoxazole using electrocatalytic reactive electrochemical membranes.

Modeling electrochemical oxidation and reduction of sulfamethoxazole using electrocatalytic reactive electrochemical membranes.

Journal of hazardous materials (2019-11-07)
Saurabh N Misal, Meng-Hsuan Lin, Shafigh Mehraeen, Brian P Chaplin
ABSTRACT

In this research, degradation of the antibiotic sulfamethoxazole (SMX) was studied using electrochemical reduction and oxidation in single pass, flow-through mode using porous titanium suboxide (Ti4O7) reactive electrochemical membranes (REMs) and Pd-Cu doped Ti4O7 REMs (Pd-Cu/Ti4O7 REMs). Electrochemical reduction of SMX increased from 3.8 ± 0.3% for the Ti4O7 REM to 96.1 ± 3.9% for the Pd-Cu/Ti4O7 REM at -1.14 V/SHE and at a permeate flux of 300 L m-2 h-1 (LMH) (liquid residence time: ∼1.8 s). By contrast, electrochemical oxidation using Ti4O7 REMs achieved 95.7 ± 1.0% removal of SMX at 2.03 V/SHE and a permeate flux of 300 LMH (liquid residence time: ∼9.0 s) without the catalyst addition. We developed a reactive transport mathematical model and calibrated it to the SMX experimental data. The calibrated model predicted SMX permeate concentrations at fixed potentials and as a function of permeate flux. Based on products from SMX reduction, we proposed that SMX was reduced by a hydrogen atom transfer reaction that was mediated by the Pd-Cu/Ti4O7 REM. Toxicity tests indicated that electrochemical oxidation/reduction lowered solution toxicity. The results of this work indicate that a tandem electrochemical reduction/oxidation approach using the REM-based technology is a potential treatment strategy for sulfonamide-contaminated pharmaceutical wastewater.

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Sodium perchlorate, ACS reagent, ≥98.0%