Thesis
Peeling a better future : development of microporous activated carbons derived from citrus waste for carbon dioxide capture
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2026
- Thesis identifier
- T18126
- Person Identifier (Local)
- 202255898
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- As worldwide reliance on fossil fuels refuses to subside, the importance of developing CarbonCapture and Storage (CCS) technologies grows. Within this field, there is a growing interestin reusable solid adsorbent materials that can be derived from sustainable sources. This studyinvestigates the production of microporous nitrogen-doped biochars and hydrochars fromsurplus citrus peels, contributing to a circular economy through valorisation of wastestreams, for use in carbon dioxide (CO?) capture systems.A robust Design of Experiments process was carried out for both biochar and hydrocharsynthesis routes to identify influential process parameters, and statistical optimisationmodels were produced, after being informed by material characterisation results. Thesemodels aimed to optimise the porosity and elemental characteristics of the materials toenhance their applicability to carbon capture technologies. The samples with the highestresponse metrics, from both synthesis routes, were then tested for their CO? adsorptionperformance and regenerative ability, under conditions analogous to industrial flue gas.Nitrogen doping, through inclusion of urea in the synthesis process, was found to successfullyincrease nitrogen content within carbonaceous chars, and activation of the chars using CO?was found to develop highly microporous materials. The highest performing sample in termsof CO? adsorption, BC Control Mandarin, exhibited CO? capacities of 0.61 mmol/g (0.1 bar)and 0.78 mmol/g (0.2 bar), at 60 °C. Meanwhile, the most effective nitrogen-doped char wasfound to be an optimised material, OPB Micropore Orange, with CO? capacities of0.48 mmol/g (0.1 bar) and 0.70 mmol/g (0.2 bar), at 60 °C. Microporosity, particularlyultramicroporosity, of the materials was found to be key to adsorption at low pressure(< 1 bar), while overall pore volume determined adsorption capacity at higher pressure (5 –19.5 bar). Meanwhile, increasing the nitrogen content of the samples was not seen to increase CO? adsorption in any meaningful way, contrasting with literature findings. Allsamples tested for their cyclic adsorption characteristics showed minimal loss in capacity,indicating high levels of regenerative ability.This study has provided a detailed and extensive comparison between two synthesis routesfor carbonaceous char sorbents, using two similar but distinct biological waste peelfeedstocks of orange and mandarin, which both descend from the Rutaceae family. Throughelemental and textural characterisation, it aims to provide an overview and assessment ofthe advantages and disadvantages of both char synthesis methods, and reaffirms the abilityof CO? to be used as an activating agent to promote micropore formation. By considering theproperties and adsorption performance of the carbonaceous char materials, it has beenestablished that Rutaceae peel-derived chars are sustainable and viable solid adsorbents forpost-combustion carbon capture applications. The Design of Experiment work in this studyalso provides a base level to progress from for further process optimisation of chars producedfrom such feedstocks.
- Advisor / supervisor
- Fletcher, Ashleigh
- Craig, Gavin
- Resource Type
- DOI
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PDF of thesis T18126 | 2026-09-08 | Public | Download |