Sarawud (Juy) Saleesongsom

Aerosol acidity, iron redox kinetics and pH measurement at the extremes of the scale.

Postdoctoral Researcher, Environmental Science Research Center (ESRC), Faculty of Science, Chiang Mai University, Thailand

Google Scholar ORCID ResearchGate GitHub LinkedIn YouTube
SS

Welcome

I am an environmental geochemist working at the boundary between aqueous chemistry and atmospheric science. My research asks how acidic an aerosol particle really is, how much water it holds, and what that means for the reactions that happen inside it, with a particular interest in the oxidation of iron(II).

Since July 2026 I have been a postdoctoral researcher at the Environmental Science Research Center of Chiang Mai University, where I study the chemistry of transboundary biomass-burning haze in Northern Thailand. I estimate size-resolved aerosol pH and aerosol liquid water content (ALWC) with thermodynamic models such as E-AIM, ISORROPIA and AIOMFAC, with the aim of improving how these models represent haze-period aerosol.

I completed my PhD in Environmental Geochemistry at Imperial College London in 2026, where I quantified how pH, temperature and speciation jointly control Fe(II) oxidation kinetics in oxygenated solutions. Along the way I developed a temperature-dependent nonlinear calibration for glass pH electrodes that extends reliable measurement to negative pH. I remain a visiting researcher at Imperial, collaborating on negative-pH chemistry and advising PhD students on computational atmospheric modelling.

I am always happy to hear from potential collaborators, students, or anyone curious about aerosol acidity. Please get in touch.

Education

PhD in Environmental Geochemistry

Oct 2021 – Mar 2026 Department of Earth Science and Engineering, Imperial College London, UK

Thesis: Quantifying the Co-dependencies of pH, Temperature, and Speciation on Iron(II) Oxidation Kinetics in Oxygenated Aqueous Solutions: Analytical Advances and Environmental Implications (DOI).

MSci Geology

Sep 2017 – Jun 2021 Department of Earth Science and Engineering, Imperial College London, UK

Thesis: Biogeochemical Modelling of Arsenic Species in Oceans. Awarded the highest MSci thesis mark in the department.

News

Research

My work combines laboratory experiments, thermodynamic and kinetic modelling, and field aerosol measurements. Four threads run through it.

Aerosol acidity and liquid water during biomass-burning haze

Every dry season, agricultural and forest fires blanket Northern Thailand in haze. I measure size-resolved aerosol composition in Chiang Mai during haze and non-haze periods and use thermodynamic models to estimate particle pH and aerosol liquid water content. Because pH controls which reactions can proceed inside a particle, these estimates matter for secondary aerosol formation, metal solubility and health-relevant chemistry. A central goal is to test and improve how current thermodynamic models handle haze-period aerosol.

E-AIM · ISORROPIA · AIOMFAC · size-resolved sampling

Fe(II) oxidation kinetics across pH and temperature

The oxidation of ferrous iron by dissolved oxygen is one of the most pH-sensitive reactions in environmental chemistry, yet rate laws for very acidic, sulphate-rich conditions have been poorly constrained. My PhD produced a coupled pH–temperature logistic rate law for Fe(II) oxidation in sulphuric acid media spanning pH −1.5 to 8.0 and 5 to 65 °C, and an experimental–computational framework for how ligands and acid systems alter the kinetics. The results feed into models of iron bioavailability in atmospheric aerosol and of sulphate-rich waters such as acid mine drainage.

UV–Vis colorimetry · PHREEQC · MINTEQ · HySS · DFT (Gaussian)

Measuring pH where the scale breaks down

Glass pH electrodes become nonlinear in concentrated acids and alkalis, which has limited quantitative work at negative pH. I developed a temperature-dependent nonlinear calibration, improved the statistical treatment of acid and alkaline errors over pH −4.5 to 15.5, and derived transferable correction factors so that other laboratories can apply the method without re-deriving it. This work includes open calibration software presented at Goldschmidt 2025.

ion-selective electrodes · Metrohm Titrando · Python · MATLAB

Adsorption kinetics of arsenic on metal oxides

As an undergraduate researcher (UROP) at Imperial College London I co-authored a study that revised the widely used pseudo-second-order (PSO) kinetic model for adsorption so that it explicitly accounts for changes in both adsorbate and adsorbent concentrations, rather than assuming a fixed excess of one over the other. To test the model, I extracted and meta-analysed 36 rate constants from 14 independent studies of arsenic adsorption onto Fe2O3 and TiO2, giving a quantitative picture of kinetic variability across systems. The work was published in Langmuir (ACS, 2021) and the dataset is openly available on Zenodo.

kinetic modelling · meta-analysis · Langmuir 2021 · Zenodo dataset

Earlier work: a global biogeochemical analysis of arsenic speciation in the oceans drawing on more than 10,000 observations (MSci thesis, Imperial College London; departmental Centenary Prize).

Positions

Postdoctoral Researcher

Jul 2026 – present Environmental Science Research Center (ESRC), Chiang Mai University, Thailand

Atmospheric aerosol chemistry of transboundary biomass-burning haze in Northern Thailand; aerosol pH and ALWC estimation using E-AIM, ISORROPIA and AIOMFAC.

Visiting Researcher

Oct 2026 – present Department of Earth Science and Engineering, Imperial College London, UK

Collaborative research on negative pH, atmospheric pollution and thermodynamic modelling.

Transition to Zero Pollution PhD student (Cohort 3)

Sep 2021 – Oct 2025 NERC Science and Solutions for a Changing Planet DTP, Grantham Institute, Imperial College London, UK

Selected as one of 10 PhD students across the College to join the Transition to Zero Pollution initiative.

UROP Research Assistant

2019 – 2020 Imperial College London, UK

Co-authored a revised pseudo-second-order adsorption kinetic model (Langmuir, 2021) and a meta-analysis of arsenic adsorption rate constants.

Awards & scholarships

Earth Science and Engineering Centenary Prize

Jun 2021 Imperial College London, UK

Departmental prize for the highest-scoring MSci thesis of the year.

TZP UROP Scholarship Scheme

Jun – Sep 2021 Imperial College London, UK

Competitive undergraduate research scholarship for independent research on marine arsenic biogeochemistry.

Development and Promotion of Science and Technology Talents Project (DPST) scholarship

May 2012 – Oct 2025 Royal Thai Government, Thailand

National scholarship fully funding education from high school through PhD, including sponsorship for overseas study.

Publications

Peer-reviewed

Under review

Thesis

Conference presentations

Data

Teaching & supervision

Research project co-supervisor

2021 – 2026 Department of Earth Science and Engineering, Imperial College London

Co-supervised six students (three UROP, two MSci and one MSc) on Fe(II) oxidation and analytical Fe(II) measurement; two achieved First-Class marks and one a high 2:1. Most recently guided an MSc project on post-rainfall PM2.5 declines in Singapore from idea development through thesis feedback.

Graduate teaching assistant

2021 – 2023 Department of Earth Science and Engineering, Imperial College London

Supported undergraduate modules in Geological Reactive Transport, Chemistry for Geoscientists and Mathematics for Geoscientists, and led Fe(II) oxidation laboratory sessions for the Environmental Geochemistry and Climate module.

Laboratory manager

Jul – Dec 2023 Environmental Geochemistry Laboratory, Imperial College London

Managed laboratory operations and inventory and trained new researchers in safety, experimental procedures and analytical instruments (UV–Vis spectrometers, Metrohm Titrando).

Seminar coordinator

Jan – Jun 2022 Department of Earth Science and Engineering, Imperial College London

Organised the departmental Environmental Science seminar series.

Science communication

Environmental Geochemistry Teaching Corner

Mar 2026 – present youtube.com/@EnvGeoChemTeachingCorner

Short explainers on current environmental geochemistry research, aimed at students and the curious public.

Science content developer

Jan – Jun 2026 Nexrise Partners Co., Ltd., Bangkok (remote)

Developed science curriculum materials across more than 180 modules in Earth science, physics and technology.

Climate science and AI evaluation

May – Dec 2025 Remote research assistant

Evaluated and refined AI-generated climate science responses across eight projects, contributing annotated data to the CLINB climate benchmark study (arXiv:2511.11597).

Skills

Modelling

  • Thermodynamic & geochemical modellingE-AIM, ISORROPIA, AIOMFAC, PHREEQC, MINTEQ, HySS, DFT (Gaussian)

Programming & data

  • Python, MATLAB, HPCData analysis, kinetic fitting, calibration software

Analytical

  • UV–Vis colorimetry (Fe, As)Ion-selective and dissolved O2 electrodes; automated titration (Metrohm Titrando)

Contact

Email
sarawudsaleesongsom@hotmail.com
Office
Environmental Science Research Center, 7th floor, 30 Years Building, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand
Profiles
Google Scholar · ORCID 0000-0002-0243-238X · ResearchGate
Elsewhere
GitHub · LinkedIn · YouTube