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Synthesis of Prussian blue-embedded porous polymer for detection and removal of Cs ions
Namgung, Ho,Gwon, Young Jin,Kim, Jongho,Jang, Geunseok,Pepper, Sarah E.,Ogden, Mark D.,Whittle, Karl R.,Harwood, Laurence M.,Lee, Taek Seung Elsevier 2018 Polymer Vol.158 No.-
<P><B>Abstract</B></P> <P>A Prussian blue (PB)-embedded coordination polymer (COP) was prepared by simple incorporation of PB into a COP composed of 1,1,2,2-tetrakis(4-carboxyphenyl)ethane and the Zn ion during the synthesis of COP. The PB-COP was prepared as micro-sized particles with green emission (490 nm) from the strongly fluorescent tetraphenylethene group in the solid state through aggregation-induced emission. The PB-COP showed particle shape with sizes ranging from 1 to 6 μm. As the PB in PB-COP efficiently adsorbed Cs ions, the microstructure of PB-COP was degraded to smaller particles, along with a concomitant decrease in the green fluorescence of the PB-COP. Such a decrease in the green emission of PB-COP was used as a signal for the presence of Cs ions, in which the limit of detection for Cs ions was found to be 73.8 ppb. The hybridized material of the PB-COP can be used as both an efficient adsorbent and a sensor for Cs ions, achieving simultaneous removal and detection.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hybrid material was prepared with coordination polymer (COP) and Prussian blue (PB). </LI> <LI> COP was prepared by ionic interaction between COOH of organic molecules and Zn ions. </LI> <LI> The hybrid materials could remove efficiently Cs ions via adsorption on PB. </LI> <LI> The fluorescence of COP in hybrid materials also decreased upon exposure to Cs ions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Cobalt and nickel uptake by silica-based extractants
Pepper, Sarah E.,Whittle, Karl R.,Harwood, Laurence M.,Cowell, Joseph,Lee, Taek Seung,Ogden, Mark D. M. Dekker 2018 Separation science and technology Vol.53 No.10
<P>The pK(a)s of ethyl/butyl phosphonate silica (EBP-Si) have been determined, and the removal of cobalt and nickel from solution was investigated as a function of various parameters and compared with those of Purolite S950. pH uptake experiments suggested a combination of ion exchange and acid dissociation of the surface occurring. Isotherm data, fitted using the Langmuir and Dubinin-Radushkevich (D-R) models, indicated that stronger complexes formed with S950 than with EBP-Si. Kinetic data, fitted using a pseudo-second-order model, suggested that the rate-determining process is the reaction of metal ions with the chelating functionality of the resin. Uptake by EBP-Si is two to three times faster than that on S950.</P>
J.T.M. Amphlett,S.E. Pepper,A.L. Riley,L.M. Harwood,J. Cowell,K.R. Whittle,T.S. Lee,M.D. Ogden 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.82 No.-
Decommissioning is one of the most important phases in the life of a nuclear reactor, having a majorinfluence on public perception of such technology. Therefore, development of technologies that makedecommissioning more safe, effective and efficient is integral to the success of the nuclear industry. Inthis paper, phosphonic acid functionalised silica has been studied to determine its suitability for treatingnuclear decommissioning effluents produced in the HYBRID process, developed in South Korea. Cu2+recovery from HCl media in both static and dynamic modes was investigated, as well as the effect of Cu2+on Co2+ and Ni2+ recovery in a column loading system. Isothermal loading studies predicted a maximumloading capacity for Cu2+ of 22.82 mg g 1, however complex loading behaviour was observed. Cu2+sorption followed pseudo-second order kinetics with rapid uptake. Thermodynamic parameters havebeen extracted from collected kinetic data. Cu2+ outcompetes both Co2+ and Ni2+ for binding to the silicain column studies, which has implications for the use of phosphonic acid functionalised silica in treatingdecommissioning effluents. This work presents initial lab scale experiments, but shows the potential of Sibased extractants for use in metals recovery in the nuclear industry.
Double-row transport in quantum wires of shallow confinement
Hew, W.K.,Thomas, K.J.,Pepper, M.,Farrer, I.,Anderson, D.,Jones, G.A.C.,Ritchie, D.A. North-Holland 2010 Physica E, Low-dimensional systems & nanostructure Vol.42 No.4
The bifurcation of the electron system in a quantum wire has been observed in the form of the suppression and disappearance of the quantised conductance plateau at 2e<SUP>2</SUP>/h. We now present low-temperature transport measurements of a top-gated split-gate quantum wire that serve to further characterise this double-row regime of transport. A small distortion of the confinement caused by asymmetrical biasing of the split gates gives rise to a radical change in the conductance characteristics of the wire, beginning with the introduction of a plateau at G=e<SUP>2</SUP>/h which rises to around 0.7x2e<SUP>2</SUP>/h with greater differential bias between the split gates. DC source-drain bias measurements in this regime show a split zero-bias peak at low conductances merging into a single peak around G=0.7xe<SUP>2</SUP>/h, which then persists up to the plateau at 4e<SUP>2</SUP>/h.
Coupled double-row formation in a quasi-1D wire
Smith, L.W.,Hew, W.K.,Thomas, K.J.,Pepper, M.,Farrer, I.,Anderson, D.,Jones, G.A.C.,Ritchie, D.A. North-Holland 2010 Physica E, Low-dimensional systems & nanostructure Vol.42 No.4
We investigate one-dimensional (1D) quantum wires in the weak confinement regime, where, at certain densities, the 1D system of electrons bifurcates into two rows. We show that the two rows are coupled, forming bonding and antibonding states, and that the coupling persists in magnetic fields from 0 to 16 T. In order for a double row to form, the Coulomb interactions in the channel must overcome the confining potential, which can be achieved by tuning the density and confinement. Using a split-gate device with a top gate and back gate, we observe a transition from single-row to double-row behaviour in the weak confinement regime. We further probe the characteristics of the coupled double row regime with dc source-drain bias measurements.
Coulomb Blockade Oscillations as a Noninvasive Probe of Screening
R. Nemutudi,C. G. Smith,C.-T. Liang,D. A. Ritchie,G. A. C. Jones,I. Farrer,M. Pepper,M. J. Murphy 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.48 No.6
Noninvasive measurement techniques utilize the fact that the local conditions in an electrical circuit can affect a nearby, but electrically isolated circuit. Such a technique can be used to measure the screening ability of an electron system. In this work, we study non-invasively the screening characteristics of a one-dimensional (1D) channel in close lateral proximity to a quantum dot that forms a separate and electrically isolated circuit. We use a one-dimensional (1D) channel to screen and in-plane electric field between the gate and the lateral quantum dot. The Coulomb blockade oscillations we observe through the quantum dot circuit and the corresponding variation in their periodicity at different gate voltage regions are a signature of the screening characteristics of a 1D channel both at zero magnetic field and in the quantum Hall region. The screening ability of the 1D channel is found to be approximately two orders of magnitude smaller than that of an ungated GaAs two-dimensional electron system.