A critical literature review suggests that carbonaceous compounds react with (CO2 +H2O) mixture through thermal, photochemical, and sonochemical/sonophysical routes. A biochar was selected for studying these effects at 60°C and 1 atm for its potential benefits on power generation and CO2 capture. All treatments remove sizable minerals (K, Na, and Si) detrimental in power generation, and introduce carbon (up to 16% of original carbon in biochar) into the biochar matrix. Most treatments show increased hydrogen (up to 24%). Treatments lead to notable increased heating value of biochar (up to 50%). Treated biochars show increase (up to 19 fold) in internal surface area. The ultrasound energy output is a fraction of the increased heating value. Thus, pretreatment is potentially attractive for increasing the energy efficiency in combustion and gasification. Moreover, better understandings of the salient reactions of these processes will be advantageous for the development of advanced adsorbents for CO2 capture. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1054–1065, 2014

The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO 2 system was studied at 25 and 40 °C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO 2 pressure is increased, the homogeneous THFWater solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure.The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS) [1][2][3][4] . For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather accurate and reproducible measurements in a timely fashion. Video LinkThe video component of this article can be found at

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