Extent Of Reaction Research Articles

Insight into the kinetic analysis of acid mine drainage treated by carbonate rock

ABSTRACT Acid mine drainage (AMD) has caused a great impact on soil, surface water, groundwater, plants or other organisms in the mining environment because of its high acidity, high sulphate content, and contains a variety of heavy metals. AMD treated by carbonate rocks have been regarded as a feasible technology for pollution control and applied widely in mine area. However, to date, the kinetics of the reaction between carbonate rock and AMD have not been investigated, resulting in the lack of systematic theoretical guidance for the implementation of this technology. In this study, effects of carbonate particle sizes and reaction temperature on AMD treatment were investigated. The dissolution efficiency of Ca2+ was used to quantitatively reflect extent of reaction, and the leaching kinetics was analysed based on the shrinking core model. The results showed that carbonate rocks with a particle size of 0.5–1.0 mm had the best pH-enhancing performance for AMD and highest removal efficiency for Fe3+ (>98.00%), while the Mn2+ and SO4 2− were temperature sensitive. The diffusion of solid product layer was the controlling step of the leaching reaction, and the apparent activation energy of the reaction was 12.63 kJ·mol−1.

Activate nutrients access to plants as multiphase slow-release fertilizers by sintering reaction in K2O–MgO–Al2O3–SiO2 system using K-feldspar as a major source

The sintering reactions in K2O–MgO–Al2O3–SiO2 system using K-feldspar, magnesite, and potassium carbonate as the starting materials were studied to prepare potassium magnesium silicates and potassium aluminosilicates as multiphase slow-release fertilizers (SRFs). Effects of sintering temperature (850–1250 °C), time (1–5 h), and addition of K2CO3 (100 %–130%) on the reaction extents as well as the types of final products were investigated. Results showed that the multi-phases of K1.14Mg0.57Si1.43O4 and KAlSiO4 were prepared as stable products under the concerned conditions of 1050 °C for 2h, and K2MgSiO4 was obtained instead of K1.14Mg0.57Si1.43O4 under the situation of adding excessive K2CO3. Sintering experiments of five raw mixtures were designed to discuss reaction mechanism by comparing the Al-phases in final products. The results indicated that Al2O3 component favored to persist as potassium aluminosilicates (KAlSiO4 or KAlSi2O6), and three multiphase compounds, KAlSiO4 + K1.14Mg0.57Si1.43O4, KAlSiO4 + K2MgSi3O8, and KAlSi2O6 + K2MgSi3O8 were successfully prepared at optimal conditions and subsequently characterized. Solubility tests of sintered samples in water, 20 g/L critic acid solution, and 0.5 mol/L hydrochloric acid solution showed that the three samples exhibited increasing solubility orderly with consistent component soluble sequence of MgO > K2O ≥ Al2O3 > SiO2 in different solutions. K1.14Mg0.57Si1.43O4 is found to perform the best soluble behavior, while KAlSi2O6 shows a less soluble behavior. Present work proposed considerable approaches to make the inert elements in minerals (K-feldspar and magnesite) and the active element (K) in potassium carbonate accessible for plants in a slow-release route.

Isomerization of galactose to tagatose using arginine as a green catalyst

This work investigated the isomerization of galactose to tagatose, a low caloric rare sugar, using arginine as a catalyst. Galactose (5 % w/v) and arginine (0.10 mol/mol-galactose) in water were treated at 90–120 °C. The results showed that as the temperature and time increased, galactose was continuously consumed. Rare sugars namely tagatose, talose, and sorbose were formed with the highest yield of 16.8, 2.7, and 3.3 %, respectively at 120 °C, 20 min. High temperature and short time conditions resulted in lower Maillard reaction extent. The arginine concentrations at 0.05, 0.10, and 0.15 mol/mol-galactose resulted in a slight increase in tagatose yield while an increase of the initial galactose concentration from 5 to 20 % resulted in a decrease in tagatose yield, although the tagatose concentration increased. The highest tagatose productivity of 278 g/(L⋅h) was obtained using galactose of 20 % w/v and arginine of 0.10 mol/mol-galactose at 120 °C and 4 min.

Capacity and Coulombic Efficiency Measurements Underestimate the Rate of SEI Growth in Silicon Anodes

Capacity measurements and related quantities are the first layer of information acquired during testing of Li-ion cells. It is generally considered that elevated values of coulombic efficiency and capacity retention are absolute indicators of the existence of a stable solid electrolyte interphase (SEI). Here, we challenge this notion by analyzing how the effect of side reactions on cell capacity depends on the choice of electrodes. More specifically, we demonstrate that the extent of measurable capacity fade due to SEI growth is modulated by the shape of the voltage profile of the cathode and anode at the end of charge and discharge half-cycles. This shape-dependency creates a mismatch between SEI growth and cell capacity loss, which is relatively small for graphite anodes but sizable for silicon-containing electrodes. We illustrate this point by showing that, at the same coulombic efficiency and capacity retention, cells containing silicon-based materials could actually exhibit rates of SEI growth that are as much as ≥ 40% higher than graphite cells. The main implication of this behavior is that, for certain systems, capacity measurements may be an unreliable source of information about the extent of reactions at the SEI, allowing other consequences of these side reactions (such as electrolyte depletion) to proceed unchecked while the cell appears to be stable.

New plasmonic sensor platform using a spatially controlled photochemical reaction and enhanced fluorescence

A plasmonic chip with a wavelength-size periodic structure coated with silver and silica layers has been applied to sensitive fluorescence observation under a microscope. In this study, to achieve more highly sensitive fluorescence detection in a spatially controlled area, an electric field enhanced with the Bull’s eye-type plasmonic chip was applied to not only the fluorescence enhancement but also the photochemical reaction field. Detecting the fluorescence signals simultaneously in-and-out of areas exposed to UV light in the single chip can improve the detection sensitivity and the accuracy. In order to construct the new sensor chip based on this concept, the surface of the chip was modified with a photoresponsive molecule 3-(2-formyl-3-methylphenyl)thio)propanoic acid (O-MBA). A plasmonic area comprising Bull’s eye patterns modified with O-MBA was exposed to ultraviolet [UV] light in the transmitted light system with an upright-inverted fluorescence microscope, and the plasmonic chip enhancement factor for the fluorescence (Ep) and the photochemical reaction promotion rate (Rp) were individually evaluated using a Cy5-Maleimide (Cy5-M), in order to indicate the essential functionality of our chip in the point of the new sensor chip. In Cy5-M, a maleimide substituent can react with intermediate of O-MBA formed photochemically and a fluorophore of Cy5 makes a roll of an indicator for extent of reaction. As the experimental results, Ep was determined to be 12.8, and the Bull’s eye pattern was found to have a twofold Rp compared with the nonpatterned area of the flat metal. The total enhancement factor above 20 and the spatial control of the area promoting a photochemical reaction will produce a highly sensitive biosensor platform.

Nonenzymatic Browning of Amorphous Maltose/Whey Protein Isolates Matrix: Effects of Water Sorption and Molecular Mobility

Nonenzymatic browning (NEB) reactions often affect the nutritional quality and safety properties of amorphous food solids. Developing a proper approach to control the NEB reaction has been of particular interest in the food industry. An NEB reaction in an amorphous maltose/Whey protein isolates (WPI) matrix containing L-lysine and D-xylose as reactants were studied at ambient temperatures aw ≤ 0.44 and 45~65 °C. The results indicated that the presence of NEB reactants barely disturbed the water sorption behavior of the matrix. The Guggenheim–Anderson–de Boer (GAB) constants and Qst values of the studied samples were affected by storage conditions as the migration of sorbed water among monolayers occurred. The rate of color changes and 5-hydoxymethylfurfural (5-HMF) accumulation on the matrix were accelerated at high ambient temperatures aw, reflecting the extent of NEB reaction increases. Since the strength concept (S) could give a measure of molecular mobility, the extent of the NEB reaction was governed by the molecular mobility of the matrix as the activation energy (Ea) of 5-HMF production minimized at solids with high S values. We found that the S concept had a considerable potential usage in controlling the NEB reaction on amorphous sugar–protein solids. This data set has practical significance in the comprehensive understanding of manipulating the diffusion-limited chemical reactions on low-moisture food solids.

Binderless ZrO2/HZSM-5 fibrillar composites by electrospinning as catalysts for the dimethyl ether-to-olefins process

The upscaling of zeolitic materials to technical catalysts implies the formulation of the active phase with additives that can affect catalytic performance. As an alternative, we herein present fibrillar ZrO2/HZSM-5 composites prepared by electrospinning where HZSM-5 zeolite aggregates are joint through inert ZrO2 fibers. For zeolite loadings of 5, 10 and 20 wt% and SiO2/Al2O3 ratios of 30, 50 and 80, well-dispersed zeolite aggregates smaller than 1.5 μm have been observed. The ZrO2/HZSM-5 composites were tested as catalysts in the dimethyl ether-to-olefins (DTO) process. The maximum olefin selectivity (ca. 70%) but fastest deactivation was observed for a zeolite loading of 5 wt%, with side reaction extent being promoted when increasing zeolite loading or density of acid sites. A comparison with a technical catalyst suggested that secondary reactions are limited due to the homogeneous distribution of the zeolite in the fibrillary material and to the higher accessibility of zeolite crystals.

Evolution of the Reaction and Alteration of Granite with Ordinary Portland Cement Leachates: Sequential Flow Experiments and Reactive Transport Modelling

The construction of a repository for the geological disposal of radioactive waste will include the use of cement-based materials. Following closure, groundwater will saturate the repository, and the extensive use of cement will result in the development of a highly alkaline porewater, pH > 12.5; this fluid will migrate into and react with the host rock. The chemistry of the fluid will evolve over time, initially with high Na and K concentrations, evolving to a Ca-rich fluid, and finally returning to the natural background groundwater composition. This evolving chemistry will affect the long-term performance of the repository, altering the physical and chemical properties, including radionuclide behaviour. Understanding these changes forms the basis for predicting the long-term evolution of the repository. This study focused on the determination of the nature and extent of the chemical reaction, as well as the formation and persistence of secondary mineral phases within a granite, comparing data from sequential flow experiments with the results of reactive transport modelling. The reaction of the granite with the cement leachates resulted in small changes in pH and the precipitation of calcium aluminium silicate hydrate (C-(A-)S-H) phases of varying compositions, of greatest abundance with the Ca-rich fluid. As the system evolved, secondary C-(A-)S-H phases redissolved, partly replaced by zeolites. This general sequence was successfully simulated using reactive transport modelling.

In Situ Investigation of Deformation Mechanisms Induced by Boron Nitride Nanotubes and Nanointerphases in Ti–6Al–4V Alloy

There is a need to augment the mechanical strength of titanium alloys to take advantage of their low mass density for structural applications. Herein, the reinforcement potential of boron nitride nanotube (BNNT), a high‐aspect‐ratio nanomaterial with exceptional strength and thermal stability, to engineer nanocomposites based on Ti–6Al–4 V alloy, is interrogated. The stress‐transfer behavior at the matrix/filler interface is programmed by tweaking the extent of chemical reactions during sintering. A twofold improvement in indentation resistance after integrating BNNTs in the alloy due to the crack bridging mechanism is reported. There is a further 50% enhancement in hardness and stiffness as the sintering temperature is raised from 750 to 950 °C. This improvement is attributed to the escalated formation of TiN and TiB phases due to matrix–nanotube interfacial reactions at elevated temperatures. A novel indentation‐based in situ trench testing technique is employed to study the subsurface deformation mechanisms activated in the bulk of the composite specimen. The ceramic interphases promote the indentation resistance by acting as crack deflectors in the microstructure, which promotes the dissipation of mechanical work. These insights can be applied to designing Ti‐BNNT microstructures with desired mechanical properties and deformation characteristics.

(Digital Presentation) Measuring Thermal Behavior of Lithium Metal Solid State Microcells with Differential Scanning Calorimetry

Research efforts in developing solid-state batteries with lithium metal anode have been on the rise owing to the high specific energy density cells using lithium metal. An all solid-state battery is often assumed to be safer compared to a Li-ion battery with an organic liquid electrolyte. If the energy density of a cell is increased through the introduction of Li metal, the potential temperature rise of the cell also increases, leading to a reduction in cell safety. In particular, during self-heating Li metal has the potential to react with the cathode itself and/or oxygen released from the cathode upon heating, as well as the solid electrolyte. The rate and extent of exothermic reactions in a specific battery chemistry and configuration determine whether self-heating could be created in a cell, as well as its onset temperature and rate. To quantify the thermal behavior of the reactions that occur within a Li metal solid state cell upon heating, we use differential scanning calorimetry (DSC). For the DSC measurements, we assemble all cell layers inside hermetically sealed stainless sealed pans, which allows us to carry out the analysis in an inert environment. With this platform, multiple cell chemistries and configurations can be tested, and the calorimetry of the reactions taking place among all cell components can be quantified. In this presentation, we will discuss our DSC measurements on select cell chemistries including with LiCoO2 and LiNi0.8Mn0.1Co0.1O2 cathodes at different states of charge, Li7La3Zr2O12 and Li3PS4 solid electrolytes, and a Li metal anode.

Irreducible IrO2 Anode Co-Catalysts for PEM Fuel Cell Voltage Reversal Mitigation and Their Stability Under Transient Operation Conditions

The cell voltage reversal that can occur during the transient operation of a proton exchange membrane fuel cell (PEMFC) stack leads to a substantial degradation of the anode catalyst. During cell reversal, the anode potential increases (>>1 V vs. the reversible hydrogen electrode potential (RHE)), causing severe oxidation of the anode catalyst carbon support, which leads to a collapse of the anode catalyst layer and to cell failure. One strategy to mitigate the damages of H2 starvation is the addition of a co-catalyst to the anode electrode, which catalyzes the oxygen evolution reaction (OER), so that the non-damaging OER rather than the damaging carbon oxidation reaction (COR) takes place. A commonly used anode co-catalyst to favor the OER over the COR during cell reversal events is iridium oxide (IrO2).1 Recent findings show that the near-surface layer(s) of IrO2 can be completely reduced to metallic Ir upon exposure to H2, e.g., under the operating conditions of a PEMFC anode.2, 3 Such alteration of the near-surface layer(s) of IrO2 drastically affects its stability during the anode potential transients that occur during start-up/shut-down (SUSD) events, where our recent study showed that the dissolution of metallic Ir and crossover of the dissolved Irn+ species through the membrane to the cathode electrode cause iridium deposition on the Pt/C cathode catalyst.3 Such iridium-based contamination on the cathode catalyst surface deteriorates the oxygen reduction reaction (ORR) activity of Pt and results in a significant performance loss during the normal operation of the fuel cell. At the same time, SUSD transients also cause an OER activity loss of the anode co-catalyst, which was shown to be mainly due to the redeposition of Pt dissolved from the anode hydrogen oxidation reaction (HOR) catalyst onto the reduced IrO2 anode co-catalyst, blocking its OER active sites.3 Since these degradation mechanisms are caused by the chemical reduction of the typically employed IrO2 anode co-catalysts in the PEMFC anode, a reduction-resistant OER catalyst would be required.In this contribution, we introduce an unprecedented approach to synthesize IrO2 catalysts that are not reduced in the PEMFC anode environment. The preparation of such irreducible IrO2 (Irr-IrO2) catalysts is based on an industrially scalable procedure consisting of a high-temperature (650-1000 ᵒC) heat treatment step followed by a deagglomeration step and a post annealing step to prepare catalyst powders with specific surface areas of ~25 m2/g. Figure 1 shows the thermogravimetric analysis (TGA) according to our previously proposed evaluation protocol3 under 3.3 vol.% H2/Ar of an as-received commercial benchmark catalyst (IrO2/TiO2 (Umicore)), a self-made IrO2 catalyst heat-treated near the conventional temperature of 500 °C (IrO2-500 °C), and a stabilized IrO2 catalyst prepared by a procedure introduced in this contribution (Irr-IrO2). It can be seen that the temperature that corresponds to the reduction of 20% of the IrO2 phase (α = 20%) of the Irr-IrO2 catalyst is ~38 °C and ~53 °C higher than those of the IrO2-500 °C and the IrO2/TiO2 (Umicore) catalysts, respectively. Considering the fact that all of these catalysts have a specific surface area of ~25 m2/g, the observed reductive stability improvement of Irr-IrO2 catalyst is due to its intrinsic structural distinctions from the typically synthesized IrO2 and the commercial benchmark IrO2 catalysts. As will be shown, this higher stability is reflected by the observation that SUSD cycling of MEAs with the Irr-IrO2 as anode co-catalyst does not result in iridium dissolution and the associated iridium poisoning of the ORR activity of the cathode catalyst. Furthermore, while its OER activity is lower than that of conventional IrO2 catalysts, it still dramatically increases the cell reversal tolerance time of a conventional Pt/C anode. References T. R. Ralph, S. Hudson, and D. P. Wilkinson, ECS Transactions, 1 (8), 67-84 (2006).P. J. Rheinländer and J. Durst, Journal of the Electrochemical Society, 168 (2), 024511 (2021).M. Fathi Tovini, A. M. Damjanovic, H. A. El-Sayed, J. Speder, C. Eickes, J.-P. Suchsland, A. Ghielmi, and H. A. Gasteiger, Journal of The Electrochemical Society, 168 (6), 064521 (2021). Figure 1. TGA (5 K min-1) experiments under 3.3 vol.% H2/Ar with the as-received IrO2/TiO2 (Umicore), the IrO2-500 °C, and the Irr-IrO2 catalyst powder samples (following a drying/cleaning step; see Ref. 3 for further details). The y-axis represents the fraction of the IrO2 phase in the catalyst powder samples that is reduced to metallic Ir (α). The black horizontal dashed line illustrates a reaction extent of α= 20%, to compare the stability of different samples in a H2-containing atmosphere. Figure 1

The user safety assessment of a selenized yeast feed additive

Purpose: Of the several selenized yeasts authorised for use as feed additives in the EU, Saccharomyces cerevisiae CNCM I-3060 inactivated’ (Sel-Plex®), was the first to be approved for use, in 2006. The additive has a concentration of selenium between 2000 and 2400 mg/kg and a selenomethionine content greater than 63%. Previous toxicological and safety studies have shown Sel-Plex® to be safe for use for target animal species, consumers, users and the environment. A new formulation of Sel-Plex® was recently developed however, with a minimum selenium content of 3000 mg/kg. The increase in selenium in this product, Sel-Plex® 3000, presented the need to assess the risk for workers and users and to establish if there would be any eye and/or skin irritancy and skin sensitisation effects associated with the product. The purpose of this paper is to present the methodology and results of the user safety skin and eye studies performed on Sel-Plex® 3000. Materials & Methods: In vitro skin and eye models were used to assess skin and eye irritancy, while skin sensitisation was examined using an in vivo method. The acute eye irritation was evaluated using a Reconstructed human Cornea-like Epithelium (RhCE) model, which followed the OECD guideline 492. The skin irritation was assessed based on its ability to induce cell death in a commercial reconstructed human epidermis (RhE) model (EPISKIN™) according to the OECD Guideline No. 439. The skin sensitising potential was evaluated in the Guinea pig in line with OECD Guideline 406, and measured the extent and degree of skin reaction to a challenge exposure following previous topical exposure of a substance on the skin. Results: The skin and eye irritation test results showed that Sel-Plex® 3000 was a non-irritant in both cases. The skin sensitisation study showed that the additive did not generate a sensitisation response in the guinea pig and should not be considered a skin sensitiser. Conclusion: These results indicate that Sel-Plex® 3000 is safe to use for workers in an industrial setting when handling the product and the studies may be further used to support regulatory compliance in respective markets.

Self-Reported and Physiologic Reactions to Third BNT162b2 mRNA COVID-19 (Booster) Vaccine Dose.

Despite extensive technological advances in recent years, objective and continuous assessment of physiologic measures after vaccination is rarely performed. We conducted a prospective observational study to evaluate short-term self-reported and physiologic reactions to the booster BNT162b2 mRNA (Pfizer-BioNTech, https://www.pfizer.com) vaccine dose. A total of 1,609 participants were equipped with smartwatches and completed daily questionnaires through a dedicated mobile application. The extent of systemic reactions reported after the booster dose was similar to that of the second dose and considerably greater than that of the first dose. Analyses of objective heart rate and heart rate variability measures recorded by smartwatches further supported this finding. Subjective and objective reactions after the booster dose were more apparent in younger participants and in participants who did not have underlying medical conditions. Our findings further support the safety of the booster dose from subjective and objective perspectives and underscore the need for integrating wearables in clinical trials.

Effect of Nuclear Radiation Generated Thermal Spike on Degradation Reaction Kinetics of a Polymer SSNTD and Its Impact on Track Diameter

It has been extensively studied that high polymer form an important group of materials used for solid state nuclear track detectors (SSNTD). The radiation induced damage not only leave tracks for microscopic examination but also change other physical properties of the material. One of them being the average molecular mass of the polymer. The change in this parameter which is induced by the radiation exposure can be studied and can give an estimate of the number of polymer chain scission, which has a direct influence on the track diameter and can give an estimate of the energy of radiation deposited inside the sample. From this the energy of the incoming particle flux can be calculated. In this paper a relationship between polymer degradation as given by the extent of the depolymerization reaction, the track diameter and energy of the incoming particle is sought.

Spectroscopic Tools to Investigate the Electrochemical Doping Kinetics and Efficiency in Organic Semiconductors

Understanding the electrochemical doping of organic semiconductors plays a crucial role in the current development of organic electronics. In this short review, we present how temperature- and time- dependent visible-near-infrared (Vis-NIR) spectro-electrochemistry and terahertz spectroscopy, combined with multivariate curve resolution analysis, can inform on the fundamental mechanisms governing the doping kinetics and efficiency of two archetypal semiconducting polymers (PEDOT and P3HT). We highlight the experimental procedures and data analysis performed to access (i) the thermodynamic parameters driving the extent and dynamics of electrochemical reactions in doped systems and (ii) how the density and nature of charged species (polarons, bipolarons) impact the charge carrier delocalization, effective THz mobility and hence short-range conductivity.

Ammonia production from nitrogen-rich biomass gasification: Nitrogen transformation from model amino acids

Ammonia (NH3) is currently being explored as a sustainable energy carrier. Ammonia production from nitrogen-rich biomass gasification provides a sustainable, distributed, and flexible process to efficient storage and conversion of renewable energy. Nitrogen is primarily in the form of proteins (amino acids) in biomass. Three amino acids, glutamic acid (Glu), glycine (Gly), and phenylalanine (Phe), with distinct structures, were screened as N-containing model compounds to assess the effects of operating conditions on nitrogen chemistry. Results indicate that chemical structure has asignificantimpact on thermal decomposition properties and N-conversion selectivity of amino acids. Gly possesses the highest NH3-N yield (∼56.4%), because the simple amino structure easily detaches as NH3. Nevertheless, Phe, as the representative of aromatic amino acids, has the lowest NH3/HCN ratio. Additionally, it is interesting to find some phenomena in common for the aromatic amino acids and aliphatic amino acids. The introduction of steam is proven to enhance the hydrogenation of char-N, the thermal cracking of tar-N, and the hydrolysis of HCN into NH3, thus promoting the NH3 selectivity. The NH3-N yield increases initially and then suppresses at 700–900 °C, which is impacted by the extent of NH3 decomposition reaction. High steam content can contribute to the enhanced availability of H radicals, consequently resulting in significant release of NH3.

Effect of re-modified nanoclays on the extent of transesterification in poly (ethylene terephthalate)/poly (ethylene 2,6-naphthalenedicarboxylate) blend nanocomposites

In the present work, the extent of transesterification reaction was investigated in the poly (ethylene terephthalate) /poly (ethylene 2,6-naphthalenedicarboxylate) (PET/PEN) (90/10 and 75/25 w/w) blends filled with three nanofillers, i.e., an organo-modified nanoclay (NC), a transition metal ion re-modified NC (TMI-NC), and a [3-(glycidyloxy)propyl]trimethoxysilane re-modified NC (GPTMS-NC). FTIR test confirmed the successful re-modification of NC. The results of the wide-angle X-ray scattering (WAXS) test revealed that the PET/PEN (75/25 w/w) blend containing 3 phr TMI-NC indicated the best intercalation. Also, the proton nuclear magnetic resonance (1 H NMR) demonstrated that the extent of transesterification was decreased by incorporating the nanofillers into the PET/PEN blend. The 75/25 blend containing 3 phr GPTMS-NC showed the highest decrement. In addition, thermogravimetric analysis (TGA) revealed that the 75/25 blend containing 3 phr TMI-NC showed the best thermal stability.

The Importance of Physiochemical Processes in Decarbonisation Technology Applications Utilizing the Subsurface: A Review

The Earth’s subsurface not only provides a wide range of natural resources but also contains large pore volume that can be used for storing both anthropogenic waste and energy. For example, geothermal energy may be extracted from hot water contained or injected into deep reservoirs and disused coal mines; CO2may be stored within depleted petroleum reservoirs and deep saline aquifers; nuclear waste may be disposed of within mechanically stable impermeable strata; surplus heat may be stored within shallow aquifers or disused coal mines. Using the subsurface in a safe manner requires a fundamental understanding of the physiochemical processes which occur when decarbonising technologies are implemented and operated. Here, thermal, hydrological, mechanical and chemical perturbations and their dynamics need to be considered. Consequently, geoscience will play a central role in Society’s quest to reduce greenhouse gas emissions. This contribution provides a review of the physiochemical processes related to key technologies that utilize the subsurface for reducing greenhouse gas emissions and the resultant challenges associated with these technologies. Dynamic links between the geomechanical, geochemical and hydrological processes differ between technologies and the geology of the locations in which such technologies are deployed. We particularly focus on processes occurring within the lithologies most commonly considered for decarbonisation technologies. Therefore, we provide a brief comparison between the lithologies, highlighting the main advantages and disadvantages of each, and provide a list of key parameters and properties which have first order effects on the performance of specific rock types, and consequently should be considered during reservoir evaluation for decarbonising technology installation. The review identifies several key knowledge gaps that need to be filled to improve reservoir evaluation and performance prediction to be able to utilize the subsurface efficiently and sustainably. Most importantly, the biggest uncertainties emerge in prediction of fracture pattern development and understanding the extent and timescales of chemical reactions that occur within the decarbonising applications where external fluid or gas is cyclically injected and invariably causes disequilibrium within the system. Furthermore, it is clear that whilst geoscience can show us the opportunities to decarbonise our cities and industries, an interdisciplinary approach is needed to realize these opportunities, also involving social science, end-users and stakeholders.

Synthesis and Evaluation of Alkyd Resins from Underutilized (Delonix Regia and Theventia Peruviana) Seed Oils

The inedibility of delonix regia and theventia peruviana seeds represents a significant waste of resources. The physicochemical properties of underutilized seed oils after refinement were studied using Association of Officials of Analytical Chemists (AOAC, 1990) techniques in this study. The refined theventia peruviana oil (RTPO) has a yield of 40.55 %, but its long alkyd resin (LTPOAR) has iodine value of 80.12 (gI2/100g), viscosity 24.17 (30o C, m2/s), saponification value of 177.04 (mg/KOH/100g), and acid value of 9.53 (mg/KOH/g), while refined delonix regia oil (RFBO) has a yield of 52.71 %, with its long alky resin (LDROAR) having iodine value of 133.87 (gI2/100g), viscosity 21.15 (30o C, m2/s), saponification value of 266.42 (mg/KOH/100g), and acid value of 5.71 (mg/KOH/g). For both TPOAR and DROAR, six grades of alkyds were created at 25 % (short), 40 % (medium), and 60 % (long) oil lengths. The acid values of the aliquots for the reaction mixture at various time intervals were used to track the reaction's progress. At the initial stage of the reaction, the extent of reaction (% Pav) ranged from 78.5 to 80.8 %, indicating a significant degree of conversion. The average degree of polymerization (Dp) of the alkyds ranged from 1.03 to 5.20, indicating the synthesis of high molecular weight alkyds. The alkyd films were acid, brine, and water resistant, but not alkali resistant. All alkyd resins were characterized with surface drying and solubility times and were found to be around 2 hours in respect of the 60% oil length.

Product distribution from pyrolysis of large biomass particle: Effects of intraparticle secondary reactions

Thermochemical conversion provides promising approaches for utilization of agroforestry residues as energy sources in rural areas, such as decentralized biomass combustion and gasification. Understanding of the pyrolysis characteristics are crucial for the design of reactors and optimization of working conditions, but in these scenarios, utilization of centimeter-sized large fuel particles will bring challenges in predicting the evolution of pyrolytic products owing to the intraparticle secondary reactions. In this work, the product distribution of biomass pyrolysis was investigated in wide ranges of temperatures and particle sizes, and special attention was paid to the pyrolysis of centimeter-sized fuel particles under medium to high temperatures (500 °C – 900 °C). The yields of solid/liquid/gas-phase products were quantified, and the composition of tar and gas products were qualitatively and quantitatively evaluated, aiming at illustrating the effects of intraparticle secondary reactions. The results have shown that the differences between the product distribution of sawdust (<1 mm) and centimeter-sized wood cubes were significant over the whole temperature range, but the differences between wood cubes with varying sizes (1 cm, 1.5 cm and 2 cm) were dependent with the external temperature, indicating that the extent of intraparticle secondary reactions was simultaneously determined by external temperature and particle size. The evolution of tar composition indicated that the intraparticle secondary reactions could be divided into two distinctive steps. Increasing the particle size would firstly result in fast consumption of primary tar species and emergence of secondary tar species, while the second step would lead to the formation of simple phenols and aromatics, and large quantities of PAHs were released for centimeter-sized fuel particle under high temperatures (≥800 °C). Kinetic analysis further revealed that the first step was mainly transport controlled and sensitive to particle size, while the second step was jointly controlled by kinetics and transport, which appeared to be significant only if the particle size was large and simultaneously the temperature was sufficiently high.