Hiroshi MACHIDA, Ryosuke TAGUCHI, Yoshiyuki SATO, Louw J. FLOURUSSE, Cor J. PETERS, Richard L. SMITH
Frontiers of Chemical Science and Engineering
2009,
Volume 3,
Issue 1,
Pages 12-19
doi:10.1007/s11705-009-0151-3
Abstract:
Ionicliquids combined with supercritical fluid technology hold great promise as working solvents for developing compact processes. Ionic liquids, which are organic molten salts, typically have extremely low volatility and high functionality, but possess high viscosities, surface tensions and low diffusion coefficients, which can limit their applicability. CO , on the other hand, especially in its supercritical state, is a green solvent that can be used advantageously when combined with the ionic liquid to provide viscosity and surface tension reduction and to promote mass transfer. The solubility of CO in the ionic liquid is key to estimating the important physical properties that include partition coefficients, viscosities, densities, interfacial tensions, thermal conductivities and heat capacities needed in contactor design. In this work, we examine a subset of available high pressure pure component ionic liquid PVT data and high pressure CO - ionic liquid solubility data and report new correlations for CO -ionic liquid systems with equations of state that have some industrial applications including: (1) general, (2) fuel desulfurization, (3) CO capture, and (4) chiral separation. New measurements of solubility data for the CO and 1-butyl-3-methylimidazolium octyl sulfate, [bmim][OcSO ] system are reported and correlated. In the correlation of the CO ionic liquid phase behavior, the Peng-Robinson and the Sanchez-Lacombe equations of state were considered and are compared. It is shown that excellent correlation of CO solubility can be obtained with either equation and they share some common characteristics regarding interaction parameters. In the Sanchez-Lacombe equation, parameters that are derived from the supercritical region were found to be important for obtaining good correlation of the CO -ionic liquid solubility data.
Yu Yang, Hassan Javed, Danning Zhang, Deyi Li, Roopa Kamath, Kevin McVey, Kanwartej Sra, Pedro J.J.
Frontiers of Chemical Science and Engineering
2017,
Volume 11,
Issue 3,
Pages 387-394
doi:10.1007/s11705-017-1657-8
Abstract:
Heavy hydrocarbons (HHCs) in soils impacted by crude oil spills are generally recalcitrant to biodegradation due to their low bioavailability and complex chemical structure. In this study, soils were pretreated with varying concentrations of ultraviolet radiation A (UVA) or ultraviolet radiation C (UVC) activated titanium dioxide (TiO ) (1%–5%) under varying moisture conditions (0%–300% water holding capacity (WHC)) to enhance biodegradation of HCCs and shorten remediation timeframes. We demonstrate that pretreatment of impacted soils with UVC-activated TiO in soil slurries could enhance bioremediation of HHCs. ?Total petroleum hydrocarbon (TPH) removal after 24 h exposure to UVC (254 nm and 4.8 mW/cm ) was (19.1±1.6)% in slurries with 300% WHC and 5 wt-% TiO . TPH removal was non-selective in the C15-C36 range and increased with moisture content and TiO concentration. In a 10-d bioremediation test, TPH removal in treated soil increased to (26.0±0.9)%, compared to (15.4±0.8)% for controls without photocatalytic pre-treatment. Enhanced biodegradation was also confirmed by respirometry. This suggests that addition of UVC-activated TiO to soil slurries can transform recalcitrant hydrocarbons into more bioavailable and biodegradable byproducts and increase the rate of subsequent biodegradation. However, similar results were not observed for soils pretreated with UVA activated TiO . This suggests that activation of TiO by sunlight and direct addition of TiO to unsaturated soils within landfarming setting may not be a feasible approach. Nevertheless, less than 1% of UVA (7.5 mW/cm ) or UVC (1.4 mW/cm ) penetrated beyond 0.3 cm soil depth, indicating that limited light penetration through soil would hinder the ability of TiO to enhance soil bioremediation under land farming conditions.
Frontiers of Chemical Science and Engineering
2016,
Volume 10,
Issue 2,
Pages 178-185
doi:10.1007/s11705-016-1558-2
Abstract:
Ribozymes are widespread, and catalyze some extremely important reactions in the cell. Mechanistically most fall into one of two classes, using either metal ions or general acid-base catalysis. The nucleolytic ribozymes fall into the latter class, mostly using nucleobases. A sub-set of these use a combination of guanine base plus adenine acid to catalyze the cleavage reaction. New ribozymes are still being discovered at regular intervals and we can speculate on the potential existence of ribozymes that catalyze chemistry beyond phosphoryl transfer reactions, perhaps using small-molecule coenzymes.
Abstract:
Throughout history mankind has sought to improve its economic and even its spiritual development through the creation of gargantuan and awe-inspiring infrastructure projects. The twenty-first century has seen the rapid growth of the use of this type of project in providing society’s needs: such projects are widely referred to as “mega-projects”. Mega-projects are extremely large-scale infrastructure projects typically costing more than $1 billion. Mega-projects include power-plant (conventional, nuclear or renewable), oil and gas extraction and processing projects and transport projects such as highways and tunnels, bridges, railways, seaports and even cultural events such as the Olympics. Mega-projects are united by their extreme complexity (both in technical and human terms) and by a long record of poor delivery. What to do in the face of this dilemma is a question that is still being asked by mega-project practitioners and academics alike. This paper presents the unique work of the MEGAPROJECT COST Action which brings together a multi-disciplinary network of over 80 researchers from 24 countries to respond to this dilemma. Mega-project’s aim involves capturing the existing performance of large infrastructural mega-projects and understanding how their delivery can be improved. In order to do this, the investigation has gathered together the MEGAPROJECT Portfolio. The Portfolio contains meta-data on a wide range of mega-projects from across countries and sectors and acts as a firm empirical foundation for the investigation’s activities. Having assembled the MEGAPROJECT Portfolio, this paper shows how analyzing the Portfolio shatters myths of mega-project management and identifies new areas of fruitful investigation. Mega-project’s findings downplay the importance of formal project management tools and techniques in insuring successful delivery. Instead mega-project highlights the need to concentrate on the impact of financing on project governance, the technical modularization of the project and the devastating roles that eternal stakeholders can have on mega-project delivery. Most importantly, it discusses how we can effectively learn across mega-projects in order to maximize their value to their stakeholders and to society as a whole.
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