Photoelectrocatalytic microreactor for seawater decontamination with negligible chlorine generation

Abstract

Decontamination of seawater is of particular importance for the waste seawater treatment before its drainage. However, some mature methods to clean waste fresh water cannot be employed to treat waste seawater due to its high slat concentration. Besides, excessive chlorine generation during the seawater decontamination process is toxic for sea creatures. In this work, a microfluidic reactor is designed and fabricated to enable the photoelectrocatalytic effect for highly-efficient seawater decontamination with negligible chlorine production. The fabricated microreactor consists of three layers: a blank indium tin oxide glass (ITO) slide serves as the cover, another ITO glass slide coated with the BiVO4 nanoporous film works as the substrate, and in between is an epoxy layer with a planar reaction chamber (10 × 10 × 0.1 mm3) and a tree-shape microchannel array. Different bias potentials are applied across the reaction chamber to decompose the methylene blue in the saline water. With the bias of ±1.8 V, the degradation rate reaches as high as about 5.3 s−1 for the negative bias and about 4.7 s−1 for the positive bias while the generated chlorine is negligible with bias up to 2.2 V. The high decontamination efficiency and elimination of chlorine generation suggest that the photoelectrocatalytic microreactor device has high potential to be scaled up for industrial applications. This also provides us an ideal platform to study the underling mechanisms and kinetics of seawater decontamination.