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
to

233 results found

Shmool TA, Martin LK, Jirkas A, Matthews RP, Constantinou AP, Vadukul DM, Georgiou TK, Aprile FA, Hallett JPet al., 2023, Unveiling the Rational Development of Stimuli-Responsive Silk Fibroin-Based Ionogel Formulations., Chem Mater, Vol: 35, Pages: 5798-5808, ISSN: 0897-4756

We present an approach for the rational development of stimuli-responsive ionogels which can be formulated for precise control of multiple unique ionogel features and fill niche pharmaceutical applications. Ionogels are captivating materials, exhibiting self-healing characteristics, tunable mechanical and structural properties, high thermal stability, and electroconductivity. However, the majority of ionogels developed require complex chemistry, exhibit high viscosity, poor biocompatibility, and low biodegradability. In our work, we overcome these limitations. We employ a facile production process and strategically integrate silk fibroin, the biocompatible ionic liquids (ILs) choline acetate ([Cho][OAc]), choline dihydrogen phosphate ([Cho][DHP]), and choline chloride ([Cho][Cl]), traditional pharmaceutical excipients, and the model antiepileptic drug phenobarbital. In the absence of ILs, we failed to observe gel formation; yet in the presence of ILs, thermoresponsive ionogels formed. Systems were assessed via visual tests, transmission electron microscopy, confocal reflection microscopy, dynamic light scattering, zeta potential and rheology measurements. We formed diverse ionogels of strengths ranging between 18 and 642 Pa. Under 25 °C storage, formulations containing polyvinylpyrrolidone (PVP) showed an ionogel formation period ranging over 14 days, increasing in the order of [Cho][DHP], [Cho][OAc], and [Cho][Cl]. Formulations lacking PVP showed an ionogel formation period ranging over 32 days, increasing in the order of [Cho][OAc], [Cho][DHP] and [Cho][Cl]. By heating from 25 to 60 °C, immediately following preparation, thermoresponsive ionogels formed below 41 °C in the absence of PVP. Based on our experimental results and density functional theory calculations, we attribute ionogel formation to macromolecular crowding and confinement effects, further enhanced upon PVP inclusion. Holistically, applying our rational development strategy enables the pr

Journal article

Verdía Barbará P, Abouelela Rafat A, Hallett JP, Brandt-Talbot Aet al., 2023, Purifying cellulose from major waste streams using ionic liquids and deep eutectic solvents, Current Opinion in Green and Sustainable Chemistry, Vol: 41, ISSN: 2452-2236

Cellulose is the main component in woody plant parts and a commodity industrial product, whose importance is set to increase as fossil hydrocarbons are phased out. Cellulose provided after a prior application can help secure stable, sustainable and cost-effective supplies of cellulosic glucose or cellulose fibers; however, the previous life poses additional challenges. Here, we discuss recent research efforts in recycling cellulose from waste biomass using ionic liquids and deep eutectic solvents, promising designer solvents for biopolymer separations. The review identifies large cellulosic waste streams that are not paper and cardboard waste, promising processing approaches employing ionic liquids and deep eutectic solvents to purify the waste cellulose, and discusses the opportunities and challenges in finding applications for the recovered cellulose. While the field of cellulosic waste recycling is relatively new, and hence decontamination and purification processes are at an early stage of development, further development has substantial potential to promote a more circular economy for cellulose.

Journal article

Al Ghatta A, Nakasu PYS, Hallett JP, 2023, Implementation of furan-based building blocks in commodity chemical production: An opinion on scientific progress and economic viability, Current Opinion in Green and Sustainable Chemistry, Vol: 41, ISSN: 2452-2236

The introduction of new green commodity chemicals is strongly dependent on developing new biobased building blocks from biomass that could allow a versatile molecular design to achieve high-performing end products. Aromaticity is one of the key features of the decision to tune the chemical and physical properties of materials and chemicals. Today, these are mostly derived from petroleum as benzene, toluene, and xylene (BTX). Furan-based alternatives are a renewable alternative and represent a topic of growing scientific interest with many publications that indirectly address this problem. However, the large-scale implementation needs of furanic compounds requires further development of several aspects within the biorefinery concept such as the integration of biomass streams, energy balance, separation and purification costs, economic feasibility, and waste disposal. In this work, we scrutinise the current scientific approach to implementing furan-based building blocks in the plastics and surfactants industry and identify areas where future research should be directed to develop a competitive and efficient biorefinery approach.

Journal article

Baaqel HA, Bernardi A, Hallett JP, Guillén-Gosálbez G, Chachuat Bet al., 2023, Global sensitivity analysis in life-cycle assessment of early-stage technology using detailed process simulation: application to dialkylimidazolium ionic liquid production., ACS Sustainable Chemistry and Engineering, Vol: 11, Pages: 7157-7169, ISSN: 2168-0485

The ability to assess the environmental performance of early-stage technologies at production scale is critical for sustainable process development. This paper presents a systematic methodology for uncertainty quantification in life-cycle assessment (LCA) of such technologies using global sensitivity analysis (GSA) coupled with a detailed process simulator and LCA database. This methodology accounts for uncertainty in both the background and foreground life-cycle inventories, and is enabled by lumping multiple background flows, either downstream or upstream of the foreground processes, in order to reduce the number of factors in the sensitivity analysis. A case study comparing the life-cycle impacts of two dialkylimidazolium ionic liquids is conducted to illustrate the methodology. Failure to account for the foreground process uncertainty alongside the background uncertainty is shown to underestimate the predicted variance of the end-point environmental impacts by a factor of two. Variance-based GSA furthermore reveals that only few foreground and background uncertain parameters contribute significantly to the total variance in the end-point environmental impacts. As well as emphasizing the need to account for foreground uncertainties in LCA of early-stage technologies, these results illustrate how GSA can empower more reliable decision-making in LCA.

Journal article

Polesca C, Al Ghatta A, Passos H, Coutinho JAP, Hallett JP, Freire MGet al., 2023, Sustainable keratin recovery process using a bio-based ionic liquid aqueous solution and its techno-economic assessment, Green Chemistry, Vol: 25, Pages: 3995-4003, ISSN: 1463-9262

Keratin is a biopolymer with high potential for biomaterial production, being principally investigated in hydrogel and film forms for use in tissue-engineering applications. Aiming to find sustainable solvents and develop an efficient keratin recovery process, this work used an aqueous solution of bio-based ionic liquid (IL) for the dissolution of chicken feathers. Complete dissolution of chicken feathers in an aqueous solution of cholinium acetate ([N111(2OH)][C1CO2]) was conducted at a solid : liquid weight ratio of 1 : 20 w/w, 100 °C for 4 h. An experimental design was carried out to optimize the keratin recovery conditions, investigating coagulant solvent, solution : coagulant weight ratio, and time. Under the optimal conditions (20.25 wt% of ethanol in water, 5 h, and solution : coagulant ratio of 1 : 1.45 w/w), 93 wt% of keratin was recovered. The IL was shown to be reusable in four successive cycles, with a yield of around 95 wt% and no significant losses in the efficiency of keratin recovery. These results demonstrate that an aqueous solution of [N111(2OH)][C1CO2] can lead to effective keratin recovery, serving as the basis for the development of a more effective and environmentally friendly process to recover biopolymers from waste. Due to the relevance of the developed process, techno-economic assessment through a comprehensive sensitivity analysis was carried out, evaluating a virtual operating biorefinery and showing a pathway that can enable the commercialization of produced keratin by the developed process. According to the process simulation, the minimum selling price for keratin is 22 $ per kg, with a small positive CO2 emission (4.04 kgCO2 kgkeratin−1), making this process suitable for biomedical and cosmetic applications.

Journal article

Aravena RI, Hallett JP, 2023, Plant sterol precipitation in system composed by fatty acids using in-situ synthesized ionic liquids, Chemical Engineering Journal, Vol: 460, ISSN: 1385-8947

Plant sterols and stanols are bio-derived compounds used in functional foods because of their hypocholesterolemic effect. Currently, plant sterols and stanols are recovered from tall oil and vegetable oil waste streams by using high vacuum distillation and crystallization. The aim of this work was to explore the recovery and purification of plant sterols and stanols using ionic liquids. Particularly, in-situ protic ionic liquids were synthesized by mixing an amine and fatty/resin acids as a model system of tall oil and vegetable oil waste streams, then an anti-solvent precipitation was performed using alcohols and water. Precipitation temperature, alcohol concentration, water concentration, type of alcohol (methanol and ethanol) and structure of amine (triethylamine, butylamine, and methyldiethanolamine) strongly affect the precipitation from model systems. On the other hand, precipitation time (3–12 h) and type of fatty/resin acid (myristic acid, oleic acid, abietic acid) only slightly influence the precipitation. Results show that when myristic acid was used, the best combination of recovery and purity is reached using triethylamine and methanol with maximum experimental values of 79.9 % of purity and 99.4 % of recovery at 5 °C, 120 % alcohol, 30 % water, and 12 h. Unfortunately, the precipitation performance of plant sterols and stanols from tall oil (5.3 %) using triethylamine and methanol is significantly worse than the performance observed in model systems, achieving maximum experimental values of 70.5 % of recovery of and 76.5 % of purity. However, it was found that saponifying the tall oil before the precipitation significantly improve plant sterols and stanols recovery and purity.

Journal article

Qu S, Hadjittofis E, Malaret F, Hallett J, Smith R, Campbell KSet al., 2023, Controlling simonkolleite crystallisation via metallic Zn oxidation in a betaine hydrochloride solution, NANOSCALE ADVANCES, ISSN: 2516-0230

Journal article

Abouelela AR, Nakasu PYS, Hallett JP, 2023, Influence of Pretreatment Severity Factor and Hammett Acidity on Softwood Fractionation by an Acidic Protic Ionic Liquid, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN: 2168-0485

Journal article

Aravena RI, Hallett JP, 2023, Protic ionic liquids based on fatty acids: A mixture of ionic and non-ionic molecules, JOURNAL OF MOLECULAR LIQUIDS, Vol: 373, ISSN: 0167-7322

Journal article

Al Ghatta A, Perry JM, Maeng H, Lemus J, Hallett JPet al., 2023, Sustainable and efficient production of furoic acid from furfural through amine assisted oxidation with hydrogen peroxide and its implementation for the synthesis of alkyl furoate, RSC Sustainability, Vol: 1, Pages: 303-309

<jats:p>Furan based building blocks have potential of introducing new commodity chemicals at low cost with low carbon impact.</jats:p>

Journal article

Al Ghatta A, Hallett JP, 2023, Bioderived furanic compounds as replacements for BTX in chemical intermediate applications, RSC Sustainability, Vol: 1, Pages: 698-745

<jats:p>Aromatic building blocks are essential chemicals to deliver high performances for a defined application. The implementation of biobased alternatives is a crucial factor for the reduction of carbon emissions and sustainability.</jats:p>

Journal article

Piercy E, Verstraete W, Ellis PR, Banks M, Rockström J, Smith P, Witard OC, Hallett J, Hogstrand C, Knott G, Karwati A, Rasoarahona HF, Leslie A, He Y, Guo Met al., 2022, A sustainable waste-to-protein system to maximise waste resource utilisation for developing food- and feed-grade protein solutions, Green Chemistry, Vol: 25, Pages: 808-832, ISSN: 1463-9262

A waste-to-protein system that integrates a range of waste-to-protein upgrading technologies has the potential to converge innovations on zero-waste and protein security to ensure a sustainable protein future. We present a global overview of food-safe and feed-safe waste resource potential and technologies to sort and transform such waste streams with compositional quality characteristics into food-grade or feed-grade protein. The identified streams are rich in carbon and nutrients and absent of pathogens and hazardous contaminants, including food waste streams, lignocellulosic waste from agricultural residues and forestry, and contaminant-free waste from the food and drink industry. A wide range of chemical, physical, and biological treatments can be applied to extract nutrients and convert waste-carbon to fermentable sugars or other platform chemicals for subsequent conversion to protein. Our quantitative analyses suggest that the waste-to-protein system has the potential to maximise recovery of various low-value resources and catalyse the transformative solutions toward a sustainable protein future. However, novel protein regulation processes remain expensive and resource intensive in many countries, with protracted timelines for approval. This poses a significant barrier to market expansion, despite accelerated research and development in waste-to-protein technologies and novel protein sources. Thus, the waste-to-protein system is an important initiative to promote metabolic health across lifespans and tackle the global hunger crisis.

Journal article

Brandl P, Bui M, Hallett JP, Mac Dowell Net al., 2022, A century of re-exploring CO2 capture solvents, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 120, ISSN: 1750-5836

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

Al Ghatta A, Aravenas RC, Wu Y, Perry JM, Lemus J, Hallett JPet al., 2022, New Biobased Sulfonated Anionic Surfactants Based on the Esterification of Furoic Acid and Fatty Alcohols: A Green Solution for the Replacement of Oil Derivative Surfactants with Superior Proprieties, ACS SUSTAINABLE CHEMISTRY & ENGINEERING, ISSN: 2168-0485

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

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