Chemical thermodynamics of aqueous electrolyte systems for industrial and environmental applications

This thesis consists of studies of chemical thermodynamics of aqueous electrolytes for industrial and environmental applications. Calculations have been used to represent vapor-liquid-solid equilibria and chemical equilibria for aqueous systems including solubility of gases. Modern simulation methods combined with experiments provide a useful tool for the research and design of new processes as well as evaluating changes in the operational conditions of chemical processes. The Gibbs energy minimization methods ChemSage, and ChemSheet have been used along with activity coefficient models including Pitzer ion interaction model. The calculated results were compared if possible with experiments or with reference data. Further this work consists of studies on oxygen-pressurized peroxide bleaching, which is an important sequence of total chlorine free (TCF) bleaching for environmental reasons. The solution properties like pH have been measured and modelled both in pure H2O2-NaOH-H2O system and in bleaching conditions. Further, the thermodynamic multicomponent model was used with kinetic constraints for pH calculations in reactive solution. The knowledge of the pulp- and solution properties along with the results of the model calculations could be used for optimisation of the bleaching process with respect to reaction time and temperature. Thermodynamics provides a practical tool for the estimation of the chemical states of pulp and paper solutions as well as in hydrometallurgical applications. Such a fundamental approach relates to the chemical energy, chemical reactions, solubility of gases and salts, and an important online process parameter pH. The Gibbs energy approach was further applied to equilibrium and reaction dynamic studies of multiphase CO2-CaCO3-H2O system.reviewe

Studies of ionic liquids in lithium-ion battery test systems

In this work, thermal and electrochemical properties of neat and mixed ionic liquid - lithium salt systems have been studied. The presence of a lithium salt causes both thermal and phase-behavior changes. Differential scanning calorimeter DSC and thermal gravimetric analysis TGA were used for thermal analysis for several imidazolium bis(trifluoromethylsulfonyl)imide, trifluoromethansulfonate, BF{sub 4}, and PF{sub 6} systems. Conductivities and diffusion coefficient have been measured for some selected systems. Chemical reactions in electrode - ionic liquid electrolyte interfaces were studied by interfacial impedance measurements. Lithium-lithium and lithium-carbon cells were studied at open circuit and a charged system. The ionic liquids studied include various imidazolium systems that are already known to be electrochemically unstable in the presence of lithium metal. In this work the development of interfacial resistance is shown in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell as well as results from some cycling experiments. As the ionic liquid reacts with the lithium electrode the interfacial resistance increases. The results show the magnitude of reactivity due to reduction of the ionic liquid electrolyte that eventually has a detrimental effect on battery performance

Mercury Removal from Concentrated Sulfuric Acid by Electrochemical Alloy Formation on Platinum

Mercury is a highly toxic heavy metal, and improved removal processes are required in a range of industrial applications to limit the environmental impacts. At present, no viable removal methods exist commercially for mercury removal of aqueous solutions at high acidic conditions, such as concentrated sulfuric acid. Herein, we show that electrochemical mercury removal based on electrochemical alloy formation on platinum, forming PtHg4, can be used to remove mercury from concentrated sulfuric acid. Thin platinum film electrodes and porous electrodes with supported platinum are used to remove more than 90% of mercury from concentrated acid from a zinc smelter with an initial mercury concentration of 0.3-0.9 mg/kg, achieving high-quality acid (<0.08 mg/kg) within 80 h. The removal process is carried out in 50 mL laboratory-scale experiments and scaled up to a 20 L pilot reactor with retained removal efficiency, highlighting excellent scalability of the method. In addition, the removal efficiency and stability of different electrode substrate materials are studied to ensure high-quality acid and a long lifetime of the electrodes in harsh chemical conditions, offering a potential method for future large-scale mercury decontamination of sulfuric acid

Ionic liquids for rechargeable lithium batteries (Preliminary report, Sept. 21, 2005)

Abstract We have investigated possible anticipated advantages of ionic-liquid electrolytes for use in lithium- Introduction A general trend in modern chemical engineering is to move to environmentally friendly processes. New chemical processes should be designed to reduce or eliminate generation of hazardous wastes. Ionic liquids are expected to provide alternatives for a variety of industrial-scale applications and for electrochemical devices. Numerous ionic liquids are known but only a small number has been investigated; for most of them, only a few properties have been studied. Because ionic liquids are nonvolatile at ordinary temperatures, and because they are non-flammable, they provide potential environmental advantages relative to conventional solvents. Properties and applicability of ionic liquids are not easily predicted. Solutes, impurities, undesired or desired reaction products alter the physical, chemical, and electrochemical behavior of a particular system. Interactions of ionic liquids with materials, or unwanted chemical reactions can eliminate the anticipated advantages in industrial applications. Knowledge of pure-component properties of ionic liquids is essential but not sufficient

Ionic liquids for rechargeable lithium batteries

We have investigated possible anticipated advantages of ionic-liquid electrolytes for use in lithium-ion batteries. Thermal stabilities and phase behavior were studied by thermal gravimetric analysis and differential scanning calorimetry. The ionic liquids studied include various imidazoliumTFSI systems, pyrrolidiniumTFSI, BMIMPF{sub 6}, BMIMBF{sub 4}, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF{sub 4}-LiBF{sub 4}, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured for various ionic-liquid lithium-salt systems. We show the development of interfacial impedance in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell and we report results from cycling experiments for a Li|BMIMBF{sub 4} + 1 mol/kg LIBF{sub 4}|C cell. The interfacial resistance increases with time and the ionic liquid reacts with the lithium electrode. As expected, imidazolium-based ionic liquids react with lithium electrodes. We seek new ionic liquids that have better chemical stabilities

Assessment of brain age in posttraumatic stress disorder: Findings from the ENIGMA PTSD and brain age working groups

Background: Posttraumatic stress disorder (PTSD) is associated with markers of accelerated aging. Estimates of brain age, compared to chronological age, may clarify the effects of PTSD on the brain and may inform treatment approaches targeting the neurobiology of aging in the context of PTSD. Method: Adult subjects (N = 2229; 56.2% male) aged 18–69 years (mean = 35.6, SD = 11.0) from 21 ENIGMA-PGC PTSD sites underwent T1-weighted brain structural magnetic resonance imaging, and PTSD assessment (PTSD+, n = 884). Previously trained voxel-wise (brainageR) and region-of-interest (BARACUS and PHOTON) machine learning pipelines were compared in a subset of control subjects (n = 386). Linear mixed effects models were conducted in the full sample (those with and without PTSD) to examine the effect of PTSD on brain predicted age difference (brain PAD; brain age − chronological age) controlling for chronological age, sex, and scan site. Results: BrainageR most accurately predicted brain age in a subset (n = 386) of controls (brainageR: ICC = 0.71, R = 0.72, MAE = 5.68; PHOTON: ICC = 0.61, R = 0.62, MAE = 6.37; BARACUS: ICC = 0.47, R = 0.64, MAE = 8.80). Using brainageR, a three-way interaction revealed that young males with PTSD exhibited higher brain PAD relative to male controls in young and old age groups; old males with PTSD exhibited lower brain PAD compared to male controls of all ages. Discussion: Differential impact of PTSD on brain PAD in younger versus older males may indicate a critical window when PTSD impacts brain aging, followed by age-related brain changes that are consonant with individuals without PTSD. Future longitudinal research is warranted to understand how PTSD impacts brain aging across the lifespan

Recovery of critical and other raw materials from mining waste and landfills

The transition to a more circular economy is essential to develop a sustainable, low carbon, resource efficient, and competitive economy in the EU. In this context Critical Raw Materials (CRM) are defined as those which are of particularly great importance to the EU economy and at the same time there is a high risk of supply disruptions. First and foremost, improving the circular use of CRM is a key strategy in improving the security of supply and not surprisingly is an objective of various policy documents. This report delivers on action #39 of the Circular Economy Action Plan: "Sharing of best practice for the recovery of critical raw materials from mining waste and landfills". It builds on discussions held during two 2018 workshops and gathers together six examples of existing practices for the recovery of critical, precious, and other materials from extractive waste and landfills, highlighting technological innovation and contributions that have been made to a more comprehensive knowledge-base on raw materials. The report also provides various estimates of potential recovery of certain materials compared to their current demand. Lessons learnt from the practices include awareness that it is very unlikely that recovery processes can target one or just a few specific materials of great interest and disregard other elements or bulk matrixes. Especially in case of very low concentrations, most of the mineral resources and other bulk materials in which they are embedded must be valorised in order to increase economic viability and minimise waste disposal. As recovery processes can be very energy intensive, environmental and land use related aspects are also particularly relevant even though environmental gains may also occur and, moreover, land space can be liberated and reused for new purposes and services. Finally, availability of data and information on secondary materials as well as a harmonized legislative framework within the EU appear to be crucial for the large-scale deployment of recovery practices.JRC.D.3-Land Resource

Assessment of Brain Age in Posttraumatic Stress Disorder: Findings from the ENIGMA PTSD and Brain Age Working Groups

Background Posttraumatic stress disorder (PTSD) is associated with markers of accelerated aging. Estimates of brain age, compared to chronological age, may clarify the effects of PTSD on the brain and may inform treatment approaches targeting the neurobiology of aging in the context of PTSD. Method Adult subjects (N = 2229; 56.2% male) aged 18–69 years (mean = 35.6, SD = 11.0) from 21 ENIGMA-PGC PTSD sites underwent T1-weighted brain structural magnetic resonance imaging, and PTSD assessment (PTSD+, n = 884). Previously trained voxel-wise (brainageR) and region-of-interest (BARACUS and PHOTON) machine learning pipelines were compared in a subset of control subjects (n = 386). Linear mixed effects models were conducted in the full sample (those with and without PTSD) to examine the effect of PTSD on brain predicted age difference (brain PAD; brain age − chronological age) controlling for chronological age, sex, and scan site. Results BrainageR most accurately predicted brain age in a subset (n = 386) of controls (brainageR: ICC = 0.71, R = 0.72, MAE = 5.68; PHOTON: ICC = 0.61, R = 0.62, MAE = 6.37; BARACUS: ICC = 0.47, R = 0.64, MAE = 8.80). Using brainageR, a three-way interaction revealed that young males with PTSD exhibited higher brain PAD relative to male controls in young and old age groups; old males with PTSD exhibited lower brain PAD compared to male controls of all ages. Discussion Differential impact of PTSD on brain PAD in younger versus older males may indicate a critical window when PTSD impacts brain aging, followed by age-related brain changes that are consonant with individuals without PTSD. Future longitudinal research is warranted to understand how PTSD impacts brain aging across the lifespan