A systematic investigation of the photocatalytic activity (PCA) of nanostructured ZnO films showed how this is directly affected by the films' morphology at different scales, from the macroscale morphology of films (e.g. thickness and surface area), to the microscale feature arrangement (e.g. aligned vs. randomly oriented structures or interpenetrated ones), to the nanoscale structure (e.g. crystal size and orientation). The interest in immobilizing photocatalysts in water treatment stems from concerns about the potential toxicity of their slurry form, which requires expensive downstream removal. Immobilisation, though, leads to a reduction in PCA, generally attributed to a lower surface area. By reducing the films' feature size to the nanoscale, an immobilized photocatalyst with high surface area can be achieved. At this scale, however, feature structuring and morphology become important as they determine the interaction between light and the photocatalytic material. In this work, nanostructured ZnO films with different morphology, arrangement and structure were produced by electrochemical anodization of zinc and were tested using the degradation of phenol in a batch reactor as a model system. Results show that the PCA for immobilized catalysts can be optimised by controlling microscale arrangement (light absorbance capacity) and nanoscale structure (crystal size and orientation) rather than macroscale morphology (surface area). These results provide a clear direction to maximising the photocatalytic activity of immobilised photocatalysts for the removal of organic pollutants from water.

Oil-in-water nanoemulsions (NEs) were produced in a dead-end stirred cell setup for the first time using bespoke anodic alumina membranes (AAMs). The regular pore structure and narrow pore size distribution of AAMs enabled the formation of NEs with narrow size distributions. Rotational speed and membrane pore size were the key parameters in controlling the droplet size, with droplets as small as 144 ± 18 nm obtained using a membrane with a pore size of 58 ± 6 nm. Low values of the droplet diameter-to-pore diameter ratio, ranging from 1.8 to 3.5 were obtained, compared to typical literature values of ~10. Literature droplet size prediction models for microemulsions overestimate results by up to ~ 600 %, whereas a model developed by the authors for NEs is much closer to experimental values. These results show that stable and controlled NEs can be produced for a variety of applications-ranging from consumer products to materials manufacturing-and, potentially, at large scale.

Advanced fertilizers are one of the top requirements to address rising global food demand. This study investigates the effect of bare and polyethylene glycol-coated FeO nanoparticles on the germination and seedling development of Phaseolus vulgaris L. Although the germination rate was not affected by the treatments (1 to 1 000 mg Fe L), seed soaking in FeO-PEG at 1 000 mg Fe L increased radicle elongation (8.1 ± 1.1 cm vs 5.9 ± 1.0 cm for the control). Conversely, Fe/Fe and bare FeO at 1 000 mg Fe L prevented the growth. X-ray spectroscopy and tomography showed that Fe penetrated in the seed. Enzymatic assays showed that FeO-PEG was the least harmful treatment to α-amylase. The growth promoted by the FeO-PEG might be related to water uptake enhancement induced by the PEG coating. These results show the potential of using coated iron nanoparticles to enhance the growth of common food crops.

Worldwide energy costs have grown in recent years due to the dwindling global fossil fuel resources and the increased reliance on them for global energy production. This is a common scenario in many nations, including Sri Lanka. As a developing country, Sri Lanka should encourage the diversification of its renewable energy supplies using locally available resources. In this regard, Sri Lanka can promote the use of agricultural residues for energy generation. The present work explores the energy potential of the solid waste generated by the rice industry: rice straw (RS) and rice husk (RH). A new approach was developed using statistical data on rice production and paddy cultivation in each district of the island. The obtained data were integrated into a geographic information system (GIS) to provide geo-referenced results. A physico-chemical characterization of the RS and RH was conducted to correlate the properties of raw materials to their potential energy generation. As an energy generation technology, the grate-fired combustion boiler accompanied by steam turbine cycle (GFC/ST) was selected. Our findings show that the total energy capacity using by-products of the rice industry is estimated to be 2129.24 ktoe/year of primary energy, with a capacity of 977 Mwe, producing 5.65 TWh of electricity annually. An economic analysis shows ten districts have a high profit index (PI > 1). The districts with the highest PI values are Anuradhapura, Ampara, Polonnaruwa, and Kurunegala, with annual energy potentials of 286 ktoe, 279 ktoe, 231 ktoe, and 160 ktoe, respectively. This work aims to aid future policy decisions by identifying potential districts in which to develop infrastructure for energy generation using agricultural waste, thus reducing net greenhouse gas emissions (GHG) of Sri Lanka.