A. (Aljosha) Hupje

Research description

Selective Removal of Hydroxylamine by induced Electric Field through Nanojunctions

Ion concentration polarization due to an applied electric field and electrical double layer overlap is a fundamental transport phenomenon which is proven in the field of desalination [1], and can be also an effective method for the separation of hydroxylamine from ammonia. To implement this approach, a microfluidic device will be used for the continuous separation of hydroxylamine. The challenge is to divide the reaction mixture into two streams, one with a high ionic conductivity mainly composing of ammonium, and the other one including neutral hydroxylamine. During operation, charged species will be pushed away from the array of nanoslots.

A glass-glass microfluidic device is designed and optimized according to this concept. The micro and nano channels are fabricated on Borofloat glass wafers by standard lithography followed by wet etching. The electrodes (Ta/Pt/Ta) are patterned on Schott glass wafers by ion beam etching. Two kinds of electrodes were designed; the voltage delivery electrodes, and conductivity measurement electrode pairs. The measurement electrodes are designed to be contactless with the electrolyte solution flowing in the micro-channels by burying them under a SiO₂ layer, whereas the voltage delivery electrodes have direct contact with solution, as DC voltage will be applied during operation. The surface of the electrode side wafers are planarized and polished prior to thermal bonding with the channel side glass wafer.

In this concept,