Thin film microfluidic reactors in electrochemical advanced oxidation processes for wastewater treatment: A review on influencing parameters, scaling issues, and engineering considerations

Abstract

The use of microfluidic electrochemical reactors has been introduced several decades ago, but their application in the field of wastewater treatment is more recent (2010). The parallel development of electrochemical advanced oxidation processes (EAOPs) as promising technologies for effluent treatment make them good candidates to be implemented as thin film cells. This allows favoring the mass transfer, which is particularly interesting for heterogenous electro-oxidation. Moreover, the energy requirement is reduced, while there is possibility to treat low-conductivity solutions. This review intends to provide instructions on the main operating parameters to be optimized during the EAOPs treatment. Directions on engineering aspects have been given to overcome the main drawbacks of microreactors such as fouling, scaling and low treatment capacity, based on recent encouraging results given in literature. The promising development of hybrid processes that combine electro-separation with electro-conversion would also benefit from such reactor designs.

Efficient lignin depolymerization by continuous flow microreactor-assisted electrochemical advanced oxidation in water/co-solvent system

“…Therefore, the reaction rate in a continuous flow microreactor system is limited by the reactant concentration instead of the concentration of OH radicals. 24 As a result, the degradation behaviour of dealkaline lignin was expected to follow the pseudo-first-order kinetic model. 43,44 To confirm the hypothesis, the effect of the residence time of dealkaline lignin in different water/co-solvent systems was fitted to pseudo-firstorder kinetic model (eqn (5)).…”

“…Microreactors are microscale reactors that, compared to typical reactors, possess a high surface-to-volume ratio, low mass and heat resistances, simplified control over residence time, and greater control of reaction parameters. [24][25][26][27] Continuous flow is the preferred system over batch processing in this context due to its highly efficient mass and heat transfer capabilities, all of which contribute to improved performance. Previously, our group reported the degradation of diuron, a chemically persistent herbicide, via EAOP in a microreactor system.…”

Fabrication, Thermo-Mechanical, and Morphological Characterization of Hydroxyapatite-Reinforced Polyurethane Biocomposites as Dye Adsorbent for Effluent

“…These include coagulation−flocculation, 8 biodegradation, 9 electrochemical oxidation, 10 ion exchange, 11 Fenton oxidation, reverse osmosis, ozonation, electrocoagulation, and adsorptive treatments. 12 Social pressure is mounting on researchers to develop environmentally friendly and economically efficient techniques. 13 Physical or chemical forces bind particles to the adsorbent during adsorption.…”

“…In the past, dye waste has been treated in many ways. These include coagulation–flocculation, biodegradation, electrochemical oxidation, ion exchange, Fenton oxidation, reverse osmosis, ozonation, electrocoagulation, and adsorptive treatments . Social pressure is mounting on researchers to develop environmentally friendly and economically efficient techniques .…”

Roles of H2 evolution overpotential, materials porosity and cathode potential on mineral electro-precipitation in microfluidic reactor – New criterion to predict and assess interdependency

“…The use of microfluidic reactors in the field of water treatment has been proven promising owing to mass transfer promotion, reduction in specific power consumption whilst allowing to treat waste effluents possessing low electrical conductivity [28][29][30][31][32][33][34][35]. However, the influence of hydrogen evolution potential and more generally of the carbon-based materials compared to metal cathode on the cathodic scaling is still questioned in such microfluidic setup and has never been elucidated yet.…”