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

239 results found

Shikh Zahari S, Liu Y, Yao P, Samirah Ideris M, Azman HH, Hallett Jet al., 2023, OPEFB pretreatment using the low-cost N,N,N-dimethylbutylammonium hydrogen sulfate ionic liquid under varying conditions, Scientific Reports, Vol: 13, ISSN: 2045-2322

This study investigates the effects of temperature and period on the pretreatment of OPEFB using the low-cost N,N,N-dimethylbutylammonium hydrogen sulfate ionic liquid ([DMBA][HSO4] IL) with 20 wt% of water. The results demonstrate that higher pretreatment temperatures (120, 150, and 170 °C) and longer periods (0.5, 1, and 2 h) enhanced lignin recovery, resulting in increased purity of the recovered pulp and subsequently enhanced glucose released during enzymatic hydrolysis. However, at 170 °C, prolonging the period led to cellulose degradation and the formation of pseudo-lignin deposited on the pulps, resulting in a decreasing-trend in glucose released. Finally, the analysis of extracted lignin reveals that increasing pretreatment severity intensified lignin depolymerisation and condensation, leading to a decrease in number average molecular weight (Mn), weight average molecular weight (Mw) and polydispersity index (Đ) values.

Journal article

Castillo Castillo A, Brophy K, Hallett J, Brandt-Talbot A, von Holstein Iet al., 2023, Addressing plastic additives, London, Publisher: Institute for Molecular Science and Engineering, Briefing topic No. 10

Hundreds of chemicals with known toxicity to humans and the environment are still widely used as additives in plastics. The average consumer’s knowledge of what goes into plastic products is not sufficient to make informed choices about exposure. The data collection needed to make these choices often does not exist, especially for recycled products made of mixtures of existing plastics. Though data on the toxicology of single additives in isolation may be available, there is very little data on the interaction of multiple additives in real world situations, either within a single product or between many products in a single place. Most substances are not restricted until proven toxic. As a result, damage comes first and action second. Substance-by-substance testing often results in the substitution of one hazardous molecule by another with similar toxicology. Governments and consumers should demand the use of non-toxic chemicals for use in plastics, especially given the risk of admixture of toxic substances in recycled plastic products. Consumers and producers should demand full supply chain transparency on additive presence in plastic products. Understanding the toxicology of mixtures of additives requires the generation of substantial new datasets. This data should include biomonitoring to characterise the complexity of real-world exposures. Assessments of toxicity should not assume that a low dose always means a low risk. Hazardous substances should be regulated by group rather than one-by-one to avoid substituting one harmful chemical for another. A molecular science and engineering approach is crucial to finding chemical and functional alternatives to toxic additives, and also for developing new processes to better manage the toxicity of additives which cannot be replaced or omitted.

Report

Anuchi SO, Campbell KLS, Hallett JP, 2023, Effects of the Ionic Liquid Structure on Porosity of Lignin-Derived Carbon Materials., ACS Sustain Chem Eng, Vol: 11, Pages: 15228-15241, ISSN: 2168-0485

Converting lignin into advanced porous carbon materials, with desirable surface functionalities, can be challenging. While lignin-derived carbons produced by pyrolysis at >600 °C develop porosity, they also simultaneously lose nearly all their surface functional groups. By contrast, pyrolysis of lignin at lower temperatures (e.g., <400 °C) results in the formation of nonporous char that retains some surface functionalities. However, copyrolysis of lignin with some ionic liquids (ILs) at lower temperatures offers an opportunity to produce porous carbon materials with both large surface areas and an abundance of surface functional groups. This study investigates the effects of IL properties (solubility, thermal, and ionic size) on the specific surface areas of lignin-derived carbons produced by copyrolysis of lignin and ILs at 350-400 °C for 20 min. It was found that ILs that have bulky anions and small cation sizes can induce porosity in lignin-derived carbons with large surface areas. Among 16 ILs that were tested, [C2MIm][NTF2] demonstrated the best performance; the inclusion of it in the copyrolysis process resulted in lignin-derived carbons with ∼528 m2 g-1 and 0.48 cm3 g-1. Lignin-derived carbons produced using no IL, [C2MIm][NTF2], and [C4MIm][OTF] were further characterized for morphology, interfacial chemical, and elemental properties. The copyrolysis of lignin and [C2MIm][NTF2], and [C4MIm][OTF] resulted in doping of heteroatoms (N and S) on the porous carbon materials during pyrolysis reaction. The present findings contribute to a better understanding of the main property of ILs responsible for creating porosity in lignin carbon during pyrolysis.

Journal article

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, CHEMISTRY OF MATERIALS, Vol: 35, Pages: 5798-5808, ISSN: 0897-4756

Journal article

Shmool TA, Hallett JP, 2023, A novel biophysical-based approach to understand the stabilisation and suppressed aggregation of protein therapeutics in ionic liquid formulations, Publisher: SPRINGER, Pages: S105-S105, ISSN: 0175-7571

Conference paper

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

Journal article

Barbara PV, Rafat AA, 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

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

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

Qu S, Hadjittofis E, Malaret F, Hallett J, Smith R, Campbell KSet al., 2023, Controlling simonkolleite crystallisation <i>via</i> metallic Zn oxidation in a betaine hydrochloride solution, NANOSCALE ADVANCES, Vol: 5, Pages: 2437-2452, ISSN: 2516-0230

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

The valorization of sugars and cellulose into high value-added compounds represents a promising alternative to petrochemical processes to produce biobased chemicals. This approach can increase sustainability and improve the environmental impact of the chemical industry. The petroleum fraction BTX, composed of benzene, toluene and the isomers of xylene, provides a large variety of bulk chemicals which are used for myriad applications, most notably for polymers and surfactants. The high demand for bioderived products which are carbon neutral has pushed research toward seeking alternative routes to replace BTX-derived compounds at large scale. Much research has been focused on lignin valorization due to its high aromatic content which can release BTX through hydrocracking, but the development of this process is limited by the low theoretical yield of useful aromatics. Cellulose and hemicellulose represent a valid alternative with the potential to synthesize a large variety of new furanic compounds which can replace aryl compounds derived from BTX. 5-HMF and furfural derived from the dehydration of sugars are the key platform chemicals for a large variety of reactions which lead to different intermediate molecules that can replace BTX with molecules that deliver the same performance or even the same molecule. 2,5-Furandicarboxylic acid (FDCA), caprolactam, phthalic anhydride, furan, maleic anhydride and alkylfurans can be derived from these molecules and can substitute petrochemical resins to obtain the resin polyethylene furoate (PEF), nylon 6,6, plasticizers and surfactants. Much research activities have been focused on the development of catalytic pathways for the efficient valorization of these molecules at high yield but few chemical routes are commercially viable. In this paper, the state of the art in obtaining valuable biobased chemical intermediates to replace BTX will be reviewed by analyzing the synthesis of 5-HMF and furfural and their further transformation

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

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

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

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

Aromatic functionality is an important feature for the design of new molecules with specific properties. Today fossil fuel feedstocks provide aryl building blocks with well-known chemistry, which can be implemented in different products for different applications. Furan building blocks are biobased chemicals derived from biomass, which have the potential to be implemented in different end products such as polymers and surfactants, substituting petrochemicals. The success in implementing furan-based compounds is strongly dependent on an efficient chemical pathway, which can give low operating costs and high yields. In this paper, we study the production of furoic acid starting from furfural through a base assisted oxidation with hydrogen peroxide. Specifically, we report a strategy to efficiently produce furoic acid and integrate this with the production of the intermediate alkyl furoate for surfactant production. Further evaluation was done on the recovery and valorisation of the co-products (sodium sulfate and amine oxide) showing that the economics of the process can be further improved. This approach can provide high reaction yield (99%) and an efficient separation of the final product, providing a valuable competitive building block for surfactant synthesis.

Journal article

Costa JM, Forster-Carneiro T, Hallett JP, 2023, Progress in the applications of biocompatible ionic liquids: renewable commodity production, catalytic and pharmaceutical approaches - a review, Green Chemistry, ISSN: 1463-9262

Millions of tons of solvents are consumed annually in various industrial sectors, such as pharmaceuticals, chemical synthesis, textiles, coatings, paints, and others. Ionic liquids (ILs) are pairs of ions in the liquid form synthesized at temperatures below 100 °C that meet specific demands of processes, replacing organic solvents that are harmful to the environment. They offer exceptional prospects as advanced solvents owing to their unique attributes and remarkable recyclability. However, alkyl imidazolium-based ILs have proven to be flammable when exposed to heat, and cytotoxicity and phytotoxicity were observed for many traditional ILs. Therefore, with a focus on negligible toxicity, biocompatibility, straightforward preparation, and sustainability, biocompatible ionic liquids (Bio-ILs) have emerged with huge potential in many different fields of chemistry. These solvents are specifically designed to be derived from naturally occurring compounds. Their physical-chemical properties, modulated according to the application, make them an attractive green technology. Therefore, this review addresses the recent advances in Bio-ILs that include the production of renewable commodities and approaches in catalysis and the pharmaceutical field. Likewise, patents and future perspectives are discussed, demonstrating the great potential of Bio-ILs as green and sustainable compounds.

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 CO<sub>2</sub> capture solvents, INTERNATIONAL JOURNAL OF GREENHOUSE GAS CONTROL, Vol: 120, ISSN: 1750-5836

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

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., 2022, 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

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