Liquid–liquid equilibria of an aqueous two-phase system consisting of poly­(ethylene oxide) 1500, sodium nitrate, and water at 293.15, 313.15, and 333.15 K were studied. Binodal data and a complete phase diagram with equilibrium liquid-phase compositions were obtained by using conductometry and refractometry techniques. The equilibrium data for aqueous two-phase systems were correlated using the UNIQUAC model, and new binary interaction parameters were calculated.

No abstract

No abstract

No abstract

No abstract

Aqueous two-phase extraction (ATPE) is a green separation technique which uses mixtures of water and environmentally benign polymers such as polyethylene glycol (PEG) as solvents. One of the challenges in implementing this extraction on an industrial scale is finding a suitable method for the isolation of target compounds from water-polymer solutions after the extraction, without diminishing ecological benefits of the method. In this paper, we propose using another green separation technique, supercritical fluid extraction (SFE), for the back-extraction of low molecular weight medium polarity compounds from ATPE solutions. Experiments with two model compounds, caffeine and benzoic acid, showed principal applicability of SFE for this task. Pressure (100–300 bar) and temperature (35–75 °C) of supercritical carbon dioxide play a major role in defining extraction capability. Extraction ratios of 35% for caffeine and 42% for benzoic acid were obtained at high fluid pressure and moderate temperature at 1:6 volume phase ratio. That gives an estimation of 10–20 theoretical steps required for complete exhaustive extraction from the ATPE solution, which is readily achievable in standard counter-current column SFE. Combining these two green methods together not only serves as an environmentally friendly method for the isolation of valuable low molecular weight compounds from diluted water solutions, but also allows for simple, energy effective recuperation of ATPE solvents.

No abstract

Making holes in soft rocks is an important aspect of mining, reclamation, and irrigation activities. Explosion techniques are effective methods of hole formation. All kinds of equipment are used to carry out microblasts with a controlled frequency at the hole face. With these techniques, soft rocks can be effectively compacted by breaking solid inclusions, enhancing borehole stability, and reducing water inflow.