Microdevice for the Reduction of Nitrate Ions Using Copper Micro-Tubular Carriers

抄録

The present study introduces a simple and inexpensive microdevice for the reduction of nitrate ions using copper micro-tubular carriers with outer and inner diameters of 0.5 and 0.2 mm, respectively. Three units consisting of seven pieces of carriers of lengths 35 mm were layered in a series in a square channel with side 2 mm in the microdevice. The performance of the microdevice was evaluated by measuring the reduction of nitrate ions in aqueous nitric acid solutions of 2.5×10⁻³, 5×10⁻³, 1×10⁻², and 2×10⁻² mol/m³ using naphthylethylenediamine absorptiometry. The reduction efficiency in a solution of 2.5×10⁻³ mol/m³ nitric acid achieved 100% at reduction times longer than 22.7 min. The Langmuir adsorption isotherm suggests that the adsorption of the nitrate ions on the copper surfaces follows the Langmuir adsorption model. Adopting copper micro-tubular carriers without cadmium as a reductant could reduce environmental loads and easily optimize the channel structure of the microdevice.