Imperial College London

Prof Jason P. Hallett

Faculty of EngineeringDepartment of Chemical Engineering

Professor of Sustainable Chemical Technology
 
 
 
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Contact

 

+44 (0)20 7594 5388j.hallett Website

 
 
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Location

 

228bBone BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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218 results found

Brandl P, Bui M, Hallett JP, Mac Dowell Net al., 2022, A century of re-exploring CO<inf>2</inf> capture solvents, International Journal of Greenhouse Gas Control, Vol: 120, ISSN: 1750-5836

Absorption-based separation processes date back over 120 years, and are recognized as being integral to the delivery of deep decarbonisation. Thousands of new solvents have been proposed but have not yet delivered the level of cost reduction which has been widely anticipated. For much of the past 50 years, the scientific community has focused on developing novel aqueous blends of amines. Whilst they outperform benchmark technologies, they ultimately fail to address the fundamental performance limiting issue; the solvents overwhelmingly consist of water. In this contribution, we present a thought-experiment that uses a hypothetical solvent to identify the limit of available cost reductions to 65% over current performance benchmarks, reaching a cost limit of $26/tonCO2 for gas-power.

Journal article

Shmool TA, Martin LK, Matthews RP, Hallett JPet al., 2022, Ionic Liquid-Based Strategy for Predicting Protein Aggregation Propensity and Thermodynamic Stability, JACS Au, ISSN: 2691-3704

Journal article

Clarke CJ, Baaqel H, Matthews RP, Chen Y, Lovelock KRJ, Hallett JP, Licence Pet al., 2022, Halometallate ionic liquids: thermal properties, decomposition pathways, and life cycle considerations, GREEN CHEMISTRY, Vol: 24, Pages: 5800-5812, ISSN: 1463-9262

Journal article

Hennequin LM, Kim S, Monroe EA, Eckles TP, Beck N, Mays WD, Fennell PS, Hallett JP, George A, Davis RWet al., 2022, Reclamation of nutrients, carbon, and metals from compromised surface waters fated to the Salton Sea: Biomass production and ecosystem services using an attached periphytic algae flow-way, ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS, Vol: 66, ISSN: 2211-9264

Journal article

Augusto FF, Francisco M, Stephen E, Jason H, van der Wielen L, Geert-Jan W, Bruno FMet al., 2022, Physicochemical Characterization of Two Protic Hydroxyethylammonium Carboxylate Ionic Liquids in Water and Their Mixture, JOURNAL OF CHEMICAL AND ENGINEERING DATA, Vol: 67, Pages: 1309-1325, ISSN: 0021-9568

Journal article

Shmool TA, Constantinou A, Jirkas A, Zhao C, Georgiou TK, Hallett Jet al., 2022, Next generation strategy for tuning the thermoresponsive properties of micellar and hydrogel drug delivery vehicles using ionic liquids, Polymer Chemistry, Vol: 13, Pages: 2340-2350, ISSN: 1759-9954

Amongst the greatest challenges in developing injectable controlled thermoresponsive micellar and hydrogel drug delivery vehicles include tuning the cloud point (CP) and reducing the gelation temperature (Tgel), below 37 °C, without compromising stability and solubility. Here, a unique strategy is employed using ionic liquid (IL) matrices to produce stable micellar and hydrogel delivery vehicles of distinct thermoresponsive properties. Each formulation includes the in-house synthesised polymer OEGMA30020-b-BuMA22-b-DEGMA11 with FITC-IgG. Both micellar-IL and hydrogel-IL formulations exhibit enhanced stability following 120 days of storage under 4 °C compared to in phosphate buffered saline (PBS). Visual tests demonstrate that the CP of the micellar-IL carriers can be finely tuned (31- 46 °C). Rheology measurements show that hydrogel strength is significantly increased and Tgel is reduced, from 40 °C in PBS to 30 °C with IL. Finally, a unique stabilisation mechanism is proposed, triggered by the synergetic action of the excipients and IL in each system

Journal article

Anuchi S, Campbell K, Hallett J, 2022, Effective pretreatment of lignin-rich coconut wastes using a low-cost ionic liquid, Scientific Reports, Vol: 12, ISSN: 2045-2322

Coconut husks and shells are underutilised agricultural feedstocks in the bio-based industry. These biomass wastes have a higher lignin content than other woody biomass and have excellent potential as raw materials for the production of lignin-based materials. This work demonstrates the performance of a low-cost protic ionic liquid, N,N,N-dimethylbutylammonium hydrogen sulfate ([DMBA][HSO4]), for ionoSolv pretreatment of coconut husk and shell at 150 °C for 45 – 90 minutes and 170 °C for 15 - 60 minutes. Optimum pretreatment conditions were observed at 170 °C and 45 minutes for both feedstocks. At these conditions, [DMBA][HSO4] was able to remove almost 77 wt.% of the lignin from the husk; leaving a cellulosic rich pulp behind, which released 82 % of the theoretical maximum glucose after enzymatic saccharification. The pretreated shell, by comparison, achieved 82 wt.% lignin removal and 89 % glucose yield and these higher values could be attributed to the highly porous structure of coconut shell cell walls. The cleavage of the β-O-4 aryl ether linkages of lignin followed by extensive C-C condensation in the lignin at longer pretreatment times was shown by HSQC NMR analysis. This extensive condensation was evidenced by molecular weights > 10 000 g/mol exhibited by lignin precipitated after pretreatment at high temperature and long times. The high degree of lignin removal and high glucose release from both feedstocks demonstrate that [DMBA][HSO4] is an excellent ionic liquid for fractionation of very lignin-rich biomass.

Journal article

Bahzad H, Fennell P, Shah N, Hallett J, Ali Net al., 2022, Techno-economic assessment for a pumped thermal energy storage integrated with open cycle gas turbine and chemical looping technology, Energy Conversion and Management, Vol: 255, Pages: 1-23, ISSN: 0196-8904

Pumped thermal energy storage offers a high energy density, potentially resulting in a relatively low cost per unit of energy stored. In this study, two novel energy storage systems were developed. The first system was developed by integrating pumped thermal energy storage and chemical looping technologies, whereas the second was formed by merging the first system with an open cycle gas turbine. Both systems used an oxygen depleted stream as a working fluid and iron-based oxygen carriers from a chemical looping water splitting process storage material for the pumped thermal energy storage system. In addition, hydrogen from the chemical looping process was employed for the gas turbine in the second system. Both systems were evaluated thermodynamically via the determination of the roundtrip efficiency. The results presented here indicate that the roundtrip efficiency of both systems developed was 77%. Furthermore, the capital requirements, operating costs, and daily profits from electricity generation were calculated for both systems over several days within the year. The capital and operating costs for the several days that were simulated for the integrated pumped thermal energy storage system were lower than that of a gas turbine based system. Consequently, the daily profit was estimated and found to be between 4.9% and 72.9% higher for the integrated pumped storage relative to the gas turbine based system. Moreover, an economic sensitivity analysis was performed to identify the factors that strongly affect the daily profits of the gas turbine system relative to the pumped storage system. Based on the analysis, the optimal hydrogen fuel percentage fed to the open cycle gas turbine was calculated for the days simulated. Finally, the impact of % error on the estimated capital and fuel production costs on daily profits were investigated. The outcome revealed a higher impact of computational errors on the fuel costs relative to the costs of the capital.

Journal article

Nakasu PYS, Barbara PV, Firth AEJ, Hallett JPet al., 2022, Pretreatment of biomass with protic ionic liquids, TRENDS IN CHEMISTRY, Vol: 4, Pages: 175-178

Journal article

Santos Klienchen Dalari BL, Giroletti CL, Malaret FJ, Skoronski E, Hallett JP, Matias WG, Puerari RC, Nagel-Hassemer MEet al., 2021, Application of a phosphonium-based ionic liquid for reactive textile dye removal: Extraction study and toxicological evaluation, JOURNAL OF ENVIRONMENTAL MANAGEMENT, Vol: 304, ISSN: 0301-4797

Journal article

Shmool T, Bhamra A, Chen R, Hallett Jet al., 2021, Stable composition

Patent

Baaqel H, Hallett JP, Guillen-Gosalbez G, Chachuat Bet al., 2021, Sustainability assessment of alternative synthesis routs to aprotic ionic liquids: the case of 1-Butyl-3-methylimidazolium tetrafluoroborate for fuel desulfurization, ACS Sustainable Chemistry and Engineering, Vol: 10, Pages: 323-331, ISSN: 2168-0485

Advantages of ionic liquids (ILs) over volatile organic solvents in chemical processes include no or negligible evaporative losses and high tunability. However, the conventional production of aprotic ILs via metathesis can be unattractive (both economically and environmentally) because of its high complexity, while the performance of other synthesis routes remains unclear. Existing life-cycle assessments furthermore fail to combine the production and use phases of these solvents, leading to erroneous conclusion about their sustainability credentials. This paper compares a one-pot, halide-free production route to 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4] against metathesis and two conventional fuel desulfurization solvents, namely, acetonitrile and dimethylformamide (DMF). Halide-free synthesis is predicted to reduce the cost and environmental impacts associated with the production of [BMIM][BF4] by 2–5-fold compared to metathesis. Upon including the use phase of the solvents in fuel desulfurization and accounting for the uncertainty in background data, halide-free [BMIM][BF4] consistently presents the lowest cost and environmental impacts, while DMF is the worst in class. As well as exemplifying the importance of synthesis routes of ILs on their sustainability, these results highlight the need to include the use phase of solvents for more comprehensive life-cycle assessments.

Journal article

Chambon CL, Verdía P, Fennell PS, Hallett Jet al., 2021, Process intensification of the ionosolv pretreatment: effects of biomass loading, particle size and 100-fold scale-up, Scientific Reports, Vol: 11, Pages: 1-15, ISSN: 2045-2322

Background: The ionoSolv process is one of the most promising technologies for biomass pretreatment in a biorefinery context. In order to evaluate the transition of the ionoSolv pretreatment of biomass from bench-scale experiments to biorefinery scale, there is a need to get better insight in process intensification. In this work, the effects of biomass loading, particle size, pulp washing protocols and 100-fold scale up for the pretreatment of the grassy biomass Miscanthus giganteus with the IL triethylammonium hydrogen sulfate, [TEA][HSO4], are presented. Results: At the bench scale, increasing biomass loading from 10 wt% to 50 wt% reduced glucose yields from 68% to 23% due to re-precipitation of lignin onto the pulp surface. Omitting the pulp air-drying step maintained saccharification yields at 66% at 50 wt% loading due to reduced fiber hornification. 100-fold scale-up (from 10 mL to 1 L) improved the efficacy of ionoSolv pretreatment and increasing loadings from 10 wt% to 20 wt% reduced lignin reprecipitation and led to higher glucose yields due to the improved heat and mass transfer caused by efficient slurry mixing in the reactor. Pretreatment of particle sizes of 1–3 mm was more effective than fine powders (0.18–0.85 mm) giving higher glucose yields due to reduced surface area available for lignin re-precipitation while reducing grinding energy needs.Conclusion: Stirred ionoSolv pretreatment showed great potential for industrialization and further process intensification after optimization of the pretreatment conditions (temperature, residence time, stirring speed), particle size and biomass loading. Pulp washing protocols need further improvement to reduce the incidence of lignin precipitation and the water requirements of lignin washing.

Journal article

Hennequin LM, Tan S-Y, Jensen E, Fennell P, Hallett JPet al., 2021, Combining phytoremediation and biorefinery: Metal extraction from lead contaminated Miscanthus during pretreatment using the ionoSolv process, INDUSTRIAL CROPS AND PRODUCTS, Vol: 176, ISSN: 0926-6690

Journal article

Abouelela AR, Al Ghatta A, Verdia P, Koo MS, Lemus J, Hallett JPet al., 2021, Evaluating the Role of Water as a Cosolvent and an Antisolvent in [HSO4]-Based Protic Ionic Liquid Pretreatment, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 10524-10536, ISSN: 2168-0485

Journal article

Upcraft T, Tu W-C, Johnson R, Finnigan T, Van Hung N, Hallett J, Guo Met al., 2021, Protein from renewable resources: mycoprotein production from agricultural residues, GREEN CHEMISTRY, Vol: 23, Pages: 5150-5165, ISSN: 1463-9262

Journal article

Shmool TA, Martin LK, Bui-Le L, Moya-Ramirez I, Kotidis P, Matthews RP, Venter GA, Kontoravdi C, Polizzi KM, Hallett JPet al., 2021, An experimental approach probing the conformational transitions and energy landscape of antibodies: a glimmer of hope for reviving lost therapeutic candidates using ionic liquid, Chemical Science, Vol: 12, Pages: 9528-9545, ISSN: 2041-6520

Understanding protein folding in different environmental conditions is fundamentally important for predicting protein structures and developing innovative antibody formulations. While the thermodynamics and kinetics of folding and unfolding have been extensively studied by computational methods, experimental methods for determining antibody conformational transition pathways are lacking. Motivated to fill this gap, we prepared a series of unique formulations containing a high concentration of a chimeric immunoglobin G4 (IgG4) antibody with different excipients in the presence and absence of the ionic liquid (IL) choline dihydrogen phosphate. We determined the effects of different excipients and IL on protein thermal and structural stability by performing variable temperature circular dichroism and bio-layer interferometry analyses. To further rationalise the observations of conformational changes with temperature, we carried out molecular dynamics simulations on a single antibody binding fragment from IgG4 in the different formulations, at low and high temperatures. We developed a methodology to study the conformational transitions and associated thermodynamics of biomolecules, and we showed IL-induced conformational transitions. We showed that the increased propensity for conformational change was driven by preferential binding of the dihydrogen phosphate anion to the antibody fragment. Finally, we found that a formulation containing IL with sugar, amino acids and surfactant is a promising candidate for stabilising proteins against conformational destabilisation and aggregation. We hope that ultimately, we can help in the quest to understand the molecular basis of the stability of antibodies and protein misfolding phenomena and offer new candidate formulations with the potential to revive lost therapeutic candidates.

Journal article

Asim AM, Uroos M, Muhammad N, Hallett JPet al., 2021, Production of Food-Grade Glucose from Rice and Wheat Residues Using a Biocompatible Ionic Liquid, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 8080-8089, ISSN: 2168-0485

Journal article

Muazzam R, Asim AM, Uroos M, Muhammad N, Hallett JPet al., 2021, Evaluating the potential of a novel hardwood biomass using a superbase ionic liquid, RSC ADVANCES, Vol: 11, Pages: 19095-19105

Journal article

Hennequin L, Sas E, Frémont A, Jerbi A, Legault N, Lamontagne J, Fagoaga N, Sarrazin M, Hallett J, Fennell P, Barnabé S, Labrecque M, Brereton N, Pitre Fet al., 2021, Biorefinery potential of sustainable municipal wastewater treatment using fast-growing willow, Science of the Total Environment, ISSN: 0048-9697

Journal article

Hallett J, 2021, Rhododendron and Japanese Knotweed: invasive species as innovative crops for second generation biofuels, RSC Advances: an international journal to further the chemical sciences, Vol: 11, Pages: 18395-18403, ISSN: 2046-2069

We investigated the potential of two terrestrial biomass invasive species in the United-Kingdom as lignocellulosic biofuel feedstocks: Japanese Knotweed (Fallopia japonica) and Rhododendron (Rhododendron ponticum). We demonstrate that a pretreatment technique using a low-cost protic ionic liquid, the ionoSolv process, can be used for such types of plant species considered as waste, to allow their integration into a biorefinery. N,N,N-Dimethylbutylammonium hydrogen sulfate ([DMBA][HSO4]) was able to fractionate the biomass into a cellulose-rich pulp and a lignin stream at high temperatures (150–170 °C) and short reaction times (15–60 minutes). More than 70–80% of the subsequent cellulose was hydrolysed into fermentable sugars, which were fermented into the renewable energy vector bioethanol.

Journal article

Clarke CJ, Morgan PJ, Hallett JP, Licence Pet al., 2021, Linking the the Thermal and Electronic Properties of Functional Dicationic Salts with their Molecular Structures, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, Vol: 9, Pages: 6224-6234, ISSN: 2168-0485

Journal article

Tan S-Y, Bedoya-Lora FE, Hallett JP, Kelsall GHet al., 2021, Evaluation of N,N,N-Dimethylbutylammonium methanesulfonate ionic liquid for electrochemical recovery of lead from lead-acid batteries, Electrochimica Acta, Vol: 376, Pages: 1-9, ISSN: 0013-4686

Physicochemical and electrochemical properties of N,N,N-dimethylbutylammonium methanesulfonate, [DMBA][MS], ionic liquid (IL) have been determined, and the potential application for electrochemical recovery of lead from lead-acid batteries is discussed. To optimise the transport properties of the IL, the dependences were measured of conductivity, density and viscosity with varying amounts of excess acid with water as a diluent in the electrolyte mixture. Molar conductivities obtained from the molar concentration and ionic conductivity measurements were used to quantify the ionicities of these IL mixtures. The solubility of PbII from PbCO3 was also shown to depend strongly on the IL composition. Preliminary results of the electrochemical kinetics of PbII reduction showed fast Pb deposition and potential-controlled electrodeposition morphologies of Pb, which may be advantageous for the design of up-scaled lead electrowinning processes.

Journal article

Yao JG, Tan S-Y, Metcalfe P, Fennell PS, Kelsall GH, Hallett JPet al., 2021, Demetallization of Sewage Sludge Using Low-Cost Ionic Liquids, ENVIRONMENTAL SCIENCE & TECHNOLOGY, Vol: 55, Pages: 5291-5300, ISSN: 0013-936X

Journal article

Clarke CJ, Matthews RP, Brogan APS, Hallett JPet al., 2021, Controlling surface chemistry and mechanical properties of metal ionogels through Lewis acidity and basicity, Journal of Materials Chemistry A, Vol: 9, Pages: 4679-4686, ISSN: 2050-7488

Ionogels are emerging as soft materials with remarkable physical properties that can be tuned to suit application requirements. The liquid component—ionic liquids—are effectively involatile, which provides new opportunities to explore gel surfaces with UHV based analytical techniques. Here, we exploit the highly solvating nature of ionic liquids to fabricate poly(ethylene glycol) based ionogels with high concentrations of zinc, and then investigate their surfaces to show that tunability extends beyond the bulk to the interface. A unique relationship between Lewis acidity and basicity and the surface concentration of metal was revealed. Chemical state analysis and molecular dynamics showed that Lewis acidic metals templated polymers to give new architectures reduced brittleness and increased flexibility, while Lewis basic metals improved polymer uniformity and strengthened gels. Therefore, bulk structure, surface composition, and metal speciation were all found to be intimately related and dependent upon the coordination strengths of ionic liquid anions. Importantly, the highly controllable surface and structural properties of metal ionogels allow fine-tuning across a broad design space, which presents new opportunities for gel based applications.

Journal article

Al Ghatta A, Zhou X, Casarano G, Wilton-Ely J, Hallett Jet al., 2021, Characterization and valorization of humins produced by HMF degradation in ionic liquids: a valuable carbonaceous material for antimony removal, ACS Sustainable Chemistry and Engineering, Vol: 9, Pages: 2212-2223, ISSN: 2168-0485

The processing of biomass in ionic liquids has demonstrated many benefits compared to organic solvents. This includes the maximization of 5-hydroxymethylfurfural (HMF) yield from sugars through the suppression of byproducts, such as formic acid and levulinic acid. Inefficiencies still exist due to the low stability of HMF at high temperature, leading to side reactions which ultimately result in the undesirable formation of humins. Valorization of this polymeric side product is thus needed to improve the economics of the biorefinery and could lead to humins being viewed as valuable materials for various applications. However, a much better understanding is needed of how humins form from HMF in the various ionic liquids proposed for the biorefinery. In this contribution, humin formation is probed by a range of analytical techniques, including FT-IR, SEM, solid-state 13C NMR, MS, GPC, and XPS analyses. This reveals that the structure and morphology of the humins formed does not resemble those reported in the literature and that the material displays a number of unique aspects. The hydrogen bonding proprieties of the ionic liquids employed exert a strong influence on the chemical functionality of the humins, and this is used to demonstrate their potential as functional materials. To demonstrate this, the humins produced in various ionic liquid environments are applied to metal extraction and compared with commercial activated carbon. This reveals that humins are superior for the extraction of antimony ions from wastewater, showing promise as an adsorbent additive for water purification.

Journal article

Cuellar-Franca RM, Garcia-Gutierrez P, Hallett JP, Mac Dowell Net al., 2021, A life cycle approach to solvent design: challenges and opportunities for ionic liquids - application to CO2 capture, REACTION CHEMISTRY & ENGINEERING, Vol: 6, Pages: 258-278, ISSN: 2058-9883

Journal article

Brandl P, Bui M, Hallett JP, Mac Dowell Net al., 2021, Beyond 90% capture: Possible, but at what cost?, International Journal of Greenhouse Gas Control, Vol: 105, Pages: 1-16, ISSN: 1750-5836

Carbon capture and storage (CCS) will have an essential role in meeting our climate change mitigation targets. CCS technologies are technically mature and will likely be deployed to decarbonise power, industry, heat, and removal of CO2 from the atmosphere. The assumption of a 90% CO2 capture rate has become ubiquitous in the literature, which has led to doubt around whether CO2 capture rates above 90% are even feasible. However, in the context of a 1.5 °C target, going beyond 90% capture will be vital, with residual emissions needing to be indirectly captured via carbon dioxide removal (CDR) technologies. Whilst there will be trade-offs between the cost of increased rates of CO2 capture, and the cost of offsets, understanding where this lies is key to minimising the dependence on CDR. This study quantifies the maximum limit of feasible CO2 capture rate for a range of power and industrial sources of CO2, beyond which abatement becomes uneconomical. In no case, was a capture rate of 90% found to be optimal, with capture rates of up to 98% possible at a relatively low marginal cost. Flue gas composition was found to be a key determinant of the cost of capture, with more dilute streams exhibiting a more pronounced minimum. Indirect capture by deploying complementary CDR is also assessed. The results show that current policy initiatives are unlikely to be sufficient to enable the economically viable deployment of CCS in all but a very few niche sectors of the economy.

Journal article

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