Photo-induced changes in the Langmuir adsorption constants of metal oxide layers in self-cleaning cation sensors.

Abstract

For the first time, we have used a metal oxide-coated quartz crystal microbalance (QCM) to measure Cs + adsorption onto illuminated and un-illuminated mesoporous TiO 2 (m-TiO 2 ) films by microgravimetric means in-situ. In the simplest case, such experiments yield two parameters of interest: K, the Langmuir adsorption coefficient and m max the maximum mass of adsorbate to form a complete monolayer at the m-TiO 2 -coated quartz crystal piezoelectric surface. Importantly, we have found that illumination of the m-TiO 2 film with ultra bandgap light results in an increase in m max i.e. illumination allows for greater adsorption of substrate to occur than in the dark. Our studies also show that under illumination, K also increases indicating a higher affinity for surface adsorption. The photoinduced change in m max and K are thought to be due to an increase in surface bound titanol groups, thus increasing the number of available adsorption sites -and so providing evidence to support the notion of photoinduced adsorption processes in photocatalytic systems. These findings have implications for the development of a reversible adsorption based microgravimetric sensor for Cs + .

Real-Time Nanogravimetric Monitoring of Corrosion in Radioactive Environments

“…Recent advances in Quartz Crystal Nanobalance technology [65] offer a means of avoiding the above disadvantages and of measuring the corrosion rates in real time and potentially in-situ.…”

Real Time Nanogravimetric Monitoring of Corrosion for Nuclear Decommissioning

“…∆f = -C f ∆m [1] Where ∆f is the change in resonant frequency (Hz), ∆m is the mass change (g) and C f is the sensitivity constant. Using the Sauerbrey equation (11) the value of C f can be determined from the resonant frequency and electroactive area of the crystals and is found to be 0.226 Hz (ng cm -2 ) for the 10 MHz crystals employed here (vide infra).…”