Nanoremediation technologies for sustainable remediation of contaminated environments: Recent advances and challenges

A major and growing concern within society is the lack of innovative and effective solutions to mitigate the challenge of environmental pollution. Uncontrolled release of pollutants into the environment as a result of urbanisation and industrialisation is a staggering problem of global concern. Although, the eco-toxicity of nanotechnology is still an issue of debate, however, nanoremediation is a promising emerging technology to tackle environmental contamination, especially dealing with recalcitrant contaminants. Nanoremediation represents an innovative approach for safe and sustainable remediation of persistent organic compounds such as pesticides, chlorinated solvents, brominated or halogenated chemicals, perfluoroalkyl and polyfluoroalkyl substances (PFAS), and heavy metals. This comprehensive review article provides a critical outlook on the recent advances and future perspectives of nanoremediation technologies such as photocatalysis, nano-sensing etc., applied for environmental decontamination. Moreover, sustainability assessment of nanoremediation technologies was taken into consideration for tackling legacy contamination with special focus on health and environmental impacts. The review further outlines the ecological implications of nanotechnology and provides consensus recommendations on the use of nanotechnology for a better present and sustainable futur

Achievement of High-Response Organic Field-Effect Transistor NO2 Sensor by Using the Synergistic Effect of ZnO/PMMA Hybrid Dielectric and CuPc/Pentacene Heterojunction

High-response organic field-effect transistor (OFET)-based NO2 sensors were fabricated using the synergistic effect the synergistic effect of zinc oxide/poly(methyl methacrylate) (ZnO/PMMA) hybrid dielectric and CuPc/Pentacene heterojunction. Compared with the OFET sensors without synergistic effect, the fabricated OFET sensors showed a remarkable shift of saturation current, field-effect mobility and threshold voltage when exposed to various concentrations of NO2 analyte. Moreover, after being stored in atmosphere for 30 days, the variation of saturation current increased more than 10 folds at 0.5 ppm NO2. By analyzing the electrical characteristics, and the morphologies of organic semiconductor films of the OFET-based sensors, the performance enhancement was ascribed to the synergistic effect of the dielectric and organic semiconductor. The ZnO nanoparticles on PMMA dielectric surface decreased the grain size of pentacene formed on hybrid dielectric, facilitating the diffusion of CuPc molecules into the grain boundary of pentacene and the approach towards the conducting channel of OFET. Hence, NO2 molecules could interact with CuPc and ZnO nanoparticles at the interface of dielectric and organic semiconductor. Our results provided a promising strategy for the design of high performance OFET-based NO2 sensors in future electronic nose and environment monitoring

OPTIMIZING POLYMERS FOR USE IN ELECTRONIC ENVIRONMENTAL SENSORS

Electronic sensors are often an ideal choice for vapor and liquid environmental monitoring due to their highly adaptable structures, rapid testing time, and simplicity of use. Biomolecule sensors achieve selectivity to a particular analyte of interest through attachment of a specific antibody to a portion of the active device substrate. Sensors for gases such as ammonia do not have the option of a selective antibody, but must instead rely on monitored molecular interactions between the active surface and the atmosphere. In both of these cases, it is of utmost importance to design the recognition layer in such a way to allow for both high specificity and high sensor output response. We can modify these films in numerous ways to achieve optimum device performance. In the following projects, I investigated some chemical and physical attachment layer optimization methods that may be used to meet specific device requirements including flexibility, portability, and rapid speed. This dissertation is broadly divided into two sections: vapor sensing (Chapter 2) and biomolecule sensing (Chapters 3 and 4). For vapor sensors, many different methods allow for increased sensitivity to target gases. The addition of metal particles and controlled porosity to a conductive film provides for increased sensitivity to ethylene, which is typically poorly reactive due to its simple chemical structure. In a separate project, two electronic devices are used in tandem with an inverter geometry to increase selectivity for ammonia sensing. This device is fabricated entirely on a plastic, flexible substrate which can be conveniently worn by an individual at risk for ammonia exposure. The biomolecular sensors presented in this work can detect the small electronic shift that occurs from protein binding to a corresponding antibody in the sensing layer. However, this attachment produces a limited voltage or current change alone. While it is common to use secondary labels and additives to increase this signal, in the case of measuring antibiotic-resistant bacteria in the field, the design is required to be as simple and portable as possible, thus limiting the possibility of complicated additives or processing. For this reason, I developed a binding polymer layer with acid-labile side chains that deprotect in the presence of pH changes. When measuring this film with electrochemical impedance spectroscopy, it is possible to see the decrease in impedance that occurs upon complementary protein binding, as the hydrophobic polymer layer degrades and allows infiltration with water