An Experimental Investigation of Ionic Vibration Potential Sensing in Electrolytes

Passing of an ultrasonic wave through an ionic solution results in distortion in electric balances between anion and cation ions, generating Ionic Vibration Potential (IVP) signals in solution for various electrolytes. In previous work, methods of Colloid Vibration Potential (CVP) imaging for characterization of nano-particle suspensions have been reported. This paper reports the further work on effect of IVP for various 1-1, 1-2 and 1-3 electrolytes, including NaCl, KCl, RbCl, CsCl, MnCl2, CuCl2, FeCl2 and FeCl3. Transition metals were chosen to understand the effect of different valences but also to understand how IVP signals change due to the closeness of atomic weight of these metals. Concentration and electrical conductivity effects were also measured. Group 1 chlorides were used to compare non-invasive imaging results with invasive imaging results from previous work. Two different valences of iron were used to investigate the effect of the number of anions on signal amplitude

Restoring earth surface processes through landform design. A 13-year monitoring of a geomorphic reclamation model for quarries on slopes

The application of geomorphic principles to land reclamation after surface mining has been reported in the literature since the mid-1990s, mostly from Australia, Canada and the USA. This paper discusses the reclamation problems of contour mining and quarries on slopes, where steep gradients are prone to both mass movement and water erosion. To address these problems simultaneously, a geomorphic model for reclaiming surface mined slopes is described. Called the ‘highwall–trench– concave slope’ model, it was fi rst applied in the 1995 reclamation of a quarry on a slope (La Revilla) in Central Spain. The geomorphic model does not reproduce the original topography, but has two very different sectors and objectives: (i) the highwall–trench sector allows the former quarry face to evolve naturally by erosion, accommodating fallen debris by means of a trench constructed at the toe of the highwall; (ii) the concave-slope base sector, mimicking the landforms of the surrounding undisturbed landscape, promotes soil formation and the establishment of self-sustaining, functional ecosystems in the area protected from sedimentation by the trench. The model improves upon simple topographic reconstruction, because it rebuilds the surfi cial geology architecture and facilitates re-establishment of equilibrium slopes through the management and control of geomorphic processes. Thirteen years of monitoring of the geomorphic and edaphic evolution of La Revilla reclaimed quarry confi rms that the area is functioning as intended: the highwall is backwasting and material is accumulating at the trench, permitting the recovery of soils and vegetation on the concave slope. However, the trench is fi lling faster than planned, which may lead to run-off and sedimentation on the concave slope once the trench is full. The lesson learned for other scenarios is that the model works well in a twodimensional scheme, but requires a three-dimensional drainage management, breaking the reclaimed area into several watersheds with stream channels

Performance Studies of Multifunctional Pt/Pd Monolithic Catalysts for Hydrocarbon Oxidation Emission Control

The catalytic aftertreatment of combustion engine exhaust is critically important to their continued use from both environmental and economic standpoints. This dissertation investigates the performance of multifunctional Pt/Pd monolithic oxidation catalysts for hydrocarbon emission control. This is accomplished through several related yet distinct studies. First, addition of zeolite beta was investigated with aim of improving cold-start performance. Focus was placed on hydrocarbon (HC) storage and light-off behavior. Dodecane (C12) and carbon monoxide (CO) were used as representative pollutants. Individual reactant feeds, co-feeds, and pre-storage experiments provided insight into the effects of additional zeolite on catalyst performance. Increased zeolite loading subsequently increased the C12 storage capacity. The zeolite did not have a notable effect on the light-off behavior for single component feeds. Pre-storing HC had an inhibitory effect on the CO-light-off and the co-feed of C12 and CO increased the CO light-off temperatures even further. Next, the construction of a spatially resolved capillary-inlet sampling system for in-channel concentration measurements is described. A study on propylene oxidation was conducted and the newly built sampling technique was utilized. A monolith reactor model was used to simulate the propylene oxidation reaction system in terms of effluent conversions and propylene concentration profiles. The model and data show good agreement. Evaluation of third party proprietary catalysts (oxidation and NSCR) was performed utilizing a more complex feed stream. The performance of these metallic substrate catalysts was compared to the model Pt/Pd catalyst, followed by additional experiments to develop a more fundamental understanding. For NSCR testing, the optimum O2 feed to convert both NOx and HC/CO was dependent on temperature. Increased methane conversion at low O2 feed concentrations prompted further investigation. Finally, methane oxidation by Pt/Pd monolith was examined over a wide range of temperatures and oxygen feed concentrations. A clockwise hysteresis loop exists in the rich regime consisting of two stable steady-states of methane conversion. The high steady-state conversion branch is eclipsed by multiple higher methane conversion branches that are transient in nature. The methane consumption observed under lean conditions is insensitive to the oxygen concentration and is classical lean methane oxidation on PdO. Spatially resolved capillary-inlet mass spectrometry (SpaciMS) measurements were utilized to reveal oxidation and partial oxidation reaction zones within the monolith catalyst. During operation in the rich regime, a front oxidative zone and downstream partial oxidation/reforming zone co-exist.Chemical and Biomolecular Engineering, Department o

Synthesis and characterization of chromium doped boehmite nanofibres

Thermogravimetric and differential thermogravimetric analysis has been used to study synthesised chromium doped boehmite. The dehydroxylation temperature increases significantly from 0% to 5% doping, after which the dehydroxylation temperature shows a small steady increase up to the 20% doping level. The temperature of dehydroxylation increases with time of hydrothermal treatment. Chromium doped boehmite nanofibres were also characterised by X-ray diffraction and transmission electron microscopy. Hydrothermal treatment of doped boehmite with chromium resulted in the formation of nanofibres over a wide dopant range. Nanofibres up to 500 nm in length and between 4-6 nm wide were produced