Environmental Research Institute - Journal Articles
Permanent URI for this collection
Browse
Recent Submissions
Item Acidogenic fermentation of Ulva in a fed-batch reactor system: tubular versus foliose biomass(Elsevier Ltd., 2025-01-08) Lawrence, James; Oliva, Armando; Murphy, Jerry D.; Lens, Piet N. L.; Science Foundatin IrelandThe present study proposes a biorefinery of the macroalgae Ulva, focusing on evaluating two different morphologies of the species (foliose and tubular) during acidogenic fermentation in fed-batch reactors. Stage 1 of the study evaluates lyophilised foliose and tubular Ulva, whilst Stage 2 analyses the impact of ulvan extraction on volatile fatty acids yield and changes in carbohydrate availability. Acetic, propionic, and butyric acids were produced from each substrate, with peak concentrations of total VFAs recorded at 2179.5 mg HAc/L (foliose Ulva) and 2029.3 mg HAc/L (tubular Ulva) when ulvan was present. After ulvan extraction, the acidogenic fermentation of the foliose morphotype was negatively affected, reaching at most 315.3 mg HAc/L. In contrast, the extraction showed no influence on the tubular morphotype, peaking at 2165.0 mg HAc/L. Additional variations were noted in the availability of carbohydrates in each substrate during the acidogenic fermentation process. The ulvan-extracted tubular morphotype exhibited the highest peak in carbohydrate concentration (9.8 g glucose/L), whilst the ulvan-extracted foliose morphotype yielded up to 8.5 g glucose/L. This study highlights the biorefinery potential of Ulva biomass, proposing a multiple cascading approach linking multiple energy and biomolecule applications to maximise the valorisation of the biomass.Item A low-carbon electricity transition for small island developing states: The case of Mauritius(Elsevier Ltd., 2024-12-20) Jaggeshar, Doorgeshwaree; Mao, Xianqiang; Guo, Zhi; Zusman, Eric; Tu, Kevin; Chen, Xing; Ma, Zhiyuan; Global Energy Interconnection GroupA clean energy transition can not only help rebuild the energy landscape of small island developing states (SIDS) but also boost their resilience and long-term development prospects. This study employs the Open-Source Energy Modeling System (OSeMOSYS) model to analyze low-carbon transition pathways for Mauritius, which are aligned with its nationally determined contribution (NDC) objectives to increase renewable energy to 60 % and phase out coal by 2030. The study applied key performance indicators to assess this pathway against energy self-sufficiency, economic, environmental and social criteria. The study showed that renewable energy sources, namely, solar, biomass, wind and waste-to-energy, can be game-changers for the island. The optimal transition pathway would achieve a renewable target of 76.8 % and reduce CO2 emissions by more than 67 % across the modeling period at an estimated cost of 1.94 billion USD by 2040. Finally, the study evaluated the implications of Mauritius' clean transition in terms of its effects on green jobs as well as whether there is sufficient infrastructure, administrative and financial capacity and energy pricing policies to support the optimal pathway. The study concludes that the experience modeling a low-carbon transition pathway for Mauritius could also offer useful lessons for other SIDS contemplating similar transitions.Item Rapid and high-precision cavity-enhanced spectroscopic measurement of HONO and NO2: Application to emissions from heavy-duty diesel vehicles in chassis dynamometer tests and in mobile monitoring(Elsevier B.V., 2025-12-16) Wang, Meng; Liu, Wenyang; Ding, Xiang; Liu, Tao; Zhou, Wenxin; Lou, Shengrong; Venables, Dean S.; Varma, Ravi; Huang, Cheng; Chen, Jun; National Natural Science Foundation of China; National Key Research and Development Program of China; Science Foundation IrelandNitrous acid (HONO) is crucial in atmospheric chemistry as it is a major precursor for hydroxyl radicals (OH), the dominant atmospheric oxidant. Hydroxyl radicals are essential in the formation of secondary air pollutants like ozone and particulate matter. This study presents a newly developed Incoherent Broadband Cavity Enhanced Absorption Spectroscopy (IBBCEAS) system for precise and rapid measurements of HONO and nitrogen dioxide (NO2) emissions. The instrument's optical cavity (formed by two mirrors separated by 96 cm and with reflectivity of 0.99955 at 378 nm) resulted in an effective optical path length of 1.4 km. With an integration time of 5 s, the 1σ measurement precisions for HONO and NO2 were 0.19 ppb and 0.48 ppb with overall measurement uncertainties of 10 % and 7 %, respectively. Comparative analysis of the IBBCEAS and a commercial cavity-attenuated phase shift (CAPS) systems under non-emission conditions demonstrated excellent agreement (slope = 1.01 and R2 = 0.98). The instrument was applied to study HONO and NO2 emissions from heavy-duty vehicles in chassis dynamometer tests and mobile monitoring. Chassis dynamometer tests revealed that HONO and NO2 emissions depend strongly on vehicle speed and driving conditions. We find a HONO/NOX ratio of 1.01 × 10−2 across the entire China-World Transient Vehicle Cycle (C-WTVC) driving cycle. Mobile monitoring in urban areas shows emission characteristics similar to those observed in chassis dynamometer tests. Frequent acceleration-deceleration patterns of diesel vehicles under congested traffic conditions lead to higher HONO and NO2 emissions compared to driving under steady speed conditions. Improving traffic flow conditions will help reduce HONO and NO2 emissions.Item Pseudo molecular doping and ambipolarity tuning in si junctionless nanowire transistors using gaseous nitrogen dioxide(Wiley, 2024) Vardhan, Vaishali; Biswas, Subhajit; Ghosh, Sayantan; Tsetseris, Leonidas; Ghoshal, Tandra; Hellebust, Stig; Georgiev, Yordan M.; Holmes, Justin D.; Horizon 2020Ambipolar transistors facilitate concurrent transport of both positive (holes) and negative (electrons) charge carriers in the semiconducting channel. Effective manipulation of conduction symmetry and electrical characteristics in ambipolar silicon junctionless nanowire transistors (Si-JNTs) is demonstrated using gaseous nitrogen dioxide (NO2). This involves a dual reaction in both p- and n-type conduction, resulting in a significant decrease in the current in n-conduction mode and an increase in the p-conduction mode upon NO2 exposure. Various Si-JNT parameters, including “on”-current (Ion), threshold voltage (Vth), and mobility (µ) exhibit dynamic changes in both the p- and n-conduction modes of the ambipolar transistor upon interaction with NO2 (concentration between 2.5 – 50 ppm). Additionally, NO2 exposure to Si-JNTs with different surface morphologies, that is, unpassivated Si-JNTs with a native oxide or with a thermally grown oxide (10 nm), show distinct influences on Ion, Vth, and µ, highlighting the effect of surface oxide on NO2-mediated charge transfer. Interaction with NO2 alters the carrier concentration in the JNT channel, with NO2 acting as an electron acceptor and inducing holes, as supported by Density Functional Theory (DFT) calculations, providing a pathway for charge transfer and “pseudo” molecular doping in ambipolar Si-JNTs.Item Nanowood: a unique natural nanomaterial that can be obtained using household chemicals(ACS Publications, 2024) Nedrygailov, Ievgen; O’Brien, Darragh.; Monaghan, Scott; Hurley, Paul K.; Biswas, Subhajit; Holmes, Justin D.; Department of Agriculture, Food and the Marine, Ireland; Horizon 2020At the nanometer scale, electrolyte solutions behave differently compared to their bulk counterparts. This phenomenon forms the basis for the field of nanofluidics, which is dedicated to studying the transport of fluids within and around objects with dimensions of less than 100 nm. Despite the increasing importance of nanofluidics for a wide range of chemical and biochemical applications, the ability to study this field in undergraduate laboratories remains limited due to challenges associated with producing suitable nanoscale objects. This article outlines a straightforward procedure, using easily accessible materials and chemical reagents, to create nanofluidic membranes, called nanowood, containing channels with diameters less than 100 nm. We describe the fabrication process of nanofluidic channels in wood and demonstrate the presence of these nanochannels based on conductance measurements using electrochemical impedance spectroscopy.