Reduction of p-nitrophenol in an airlift electrochemical reactor with iron electrodes

AbstractThe electrocatalytic nitrogen (N2) reduction reaction (NRR) relies on the development of highly efficient electrocatalysts and electrocatalysis systems. Herein, we report a non-loading electrocatalysis system, where the electrocatalysts are dispersed in aqueous solution rather than loading them on electrode substrates. The system consists of aqueous Ag nanodots (AgNDs) as the catalyst and metallic titanium (Ti) mesh as the current collector for electrocatalytic NRR. The as-synthesized AgNDs, homogeneously dispersed in 0.1 M Na2SO4 solution (pH = 10.5), can achieve an NH3 yield rate of 600.4 ± 23.0 μg h−1 mgAg−1 with a faradaic efficiency (FE) of 10.1 ± 0.7% at −0.25 V (vs. RHE). The FE can be further improved to be 20.1 ± 0.9% at the same potential by using Ti mesh modified with oxygen vacancy-rich TiO2 nanosheets as the current collector. Utilizing the aqueous AgNDs catalyst, a Ti plate based two-electrode configured flow-type electrochemical reactor was developed to achieve an NH3 yield rate of 804.5 ± 30.6 μg h−1 mgAg−1 with a FE of 8.2 ± 0.5% at a voltage of −1.8 V. The designed non-loading electrocatalysis system takes full advantage of the AgNDs’ active sites for N2 adsorption and activation, following an alternative hydrogenation mechanism revealed by theoretical calculations.

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Design methodology for mass transfer-enhanced large-scale electrochemical reactor for CO2 reduction

Chemical Engineering Journal ◽

10.1016/j.cej.2021.130265 ◽

2021 ◽

pp. 130265

Author(s):

Byungchan Jung ◽

Seongho Park ◽

Chulwan Lim ◽

Woonghee Lee ◽

Youngsub Lim ◽

...

Keyword(s):

Mass Transfer ◽

Design Methodology ◽

Large Scale ◽

Co2 Reduction ◽

Electrochemical Reactor

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Arsenic Removal by Advanced Electrocoagulation Processes: The Role of Oxidants Generated and Kinetic Modeling

Catalysts ◽

10.3390/catal10080928 ◽

2020 ◽

Vol 10 (8) ◽

pp. 928

Author(s):

Micah Flor V. Montefalcon ◽

Meliton R. Chiong ◽

Augustus C. Resurreccion ◽

Sergi Garcia-Segura ◽

Joey D. Ocon

Keyword(s):

Kinetic Modeling ◽

Arsenic Removal ◽

Fold Increase ◽

Electrochemical Treatment ◽

Promising Alternative ◽

Iron Electrodes ◽

Removal Capacity ◽

Naturally Occurring ◽

Treatment Technologies

Arsenic (As) is a naturally occurring element in the environment that poses significant risks to human health. Several treatment technologies have been successfully used in the treatment of As-contaminated waters. However, limited literature has explored advanced electrocoagulation (EC) processes for As removal. The present study evaluates the As removal performance of electrocoagulation, electrochemical peroxidation (ECP), and photo-assisted electrochemical peroxidation (PECP) technologies at circumneutral pH using electroactive iron electrodes. The influence of As speciation and the role of oxidants in As removal were investigated. We have identified the ECP process to be a promising alternative for the conventional EC with around 4-fold increase in arsenic removal capacity at a competitive cost of 0.0060 $/m3. Results also indicated that the rate of As(III) oxidation at the outset of electrochemical treatment dictates the extent of As removal. Both ECP and PECP processes reached greater than 96% As(III) conversion at 1 C/L and achieved 86% and 96% As removal at 5 C/L, respectively. Finally, the mechanism of As(III) oxidation was evaluated, and results showed that Fe(IV) is the intermediate oxidant generated in advanced EC processes, and the contribution of •OH brought by UV irradiation is insignificant.

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