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A laboratory-scale packed column was positioned on a six degree of freedom swell simulation hexapod to emulate the hydrodynamics of packed bed scrubbers/reactors onboard offshore floating systems. The bed was instrumented with wire mesh capacitance sensors to measure liquid saturation and velocity fields, flow regime transition, liquid maldistribution, and tracer radial and axial dispersion patterns while robot was subject to sinusoidal translation (sway, heave) and rotation (roll, roll 1 pitch, yaw) motions at different frequencies. Three metrics were defined to analyze the deviations induced by the various column motions, namely, coefficient of variation and degree of uniformity for liquid saturation fluctuating fields, and effective P eclet number. Nontilting oscillations led to frequency-independent maldistribution while tilting motions induced swirl/zigzag secondary circulation and prompted nonuniform maldistribution oscillations that deteriorated with decreasing frequencies. Regardless of excited degree of freedom, a qualitative loss of plug-flow character was observed compared with static vertical beds which worsened as frequencies decreased.

Factors affecting carbon dioxide fixation in chrysotile mining residues (CMR) under environmental conditions were studied by reproducing mineral dissolution and carbonation in laboratory columns packed with CMR particles. Carbonation is very sensitive to water saturation and watering frequency of the CMR porous media. CO 2 uptake by dry residues subjected to dry CO 2 flow for several days at ambient temperature was below 0.02%. However, an increase by a factor of 20 in CO 2 uptake was achieved by periodic addition of small amounts of water with respect to a moistened CO 2 stream over dry CMR samples. The highest MgCO 3 conversion resulted in nearly 22 mg of CO 2 captured per gram of residue, revealing that up to 93% of Mg remained noncarbonated because of surface obstructing processes. Magnesium leaching from CMR was hindered by two concomitant passivation phenomena limiting the residue's CO 2 storage capacity. A unique cyclic voltammetry technique using oxic and anoxic aqueous solutions contacted with CMR fixed beds was implemented to assess the relative importance from CMR-borne iron electrochemical passivation and silica-deposit nonelectrochemical passivation. Passivation around the dissolving CMR particles by iron hydroxide precipitation was found to develop very rapidly in comparison to silica gel polymerization.■ EXPERIMENTAL SECTION Material Characterization. Chrysotile mining residues (CMR) as received from the Black Lake mine (Thetford Mines,

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