The global population is constantly rising and with the consequent increase in demand for clean water, the planet is facing a looming freshwater shortage. At the current rate, cities around the globe could lose as much as two thirds of their freshwater supply by 2050. To tackle this, there has been a huge surge on the investigation of novel wastewater treatment technologies. Advanced oxidation processes (AOPs) have shown great promise in this regard. Recently using microwaves with AOPs has been proven to exhibit improved reaction rates and thus there is a push towards developing processes involving microwaves and AOPs to achieve high water treatment efficiencies. However no methodical studies have been conducted to the best of our knowledge, to take the lab scale improvements successfully on to the pilot scale wastewater treatment system. To design such a system by coupling microwaves with Fenton process is the objective of this microwave assisted catalytic treatment of wastewater (MICROCAT) research project. Multiphysics simulation was used for cavity design optimisation and common pesticides found in agricultural wastewater were used as candidate impurities. A heterogeneous Fenton catalyst was prepared by a multi-stage thermal and chemical treatment of polyacrylonitrile (PAN) mesh on polypropylene support structure in collaboration with De Montfort University (DMU). The PAN meshes, after each stage of the treatment process, have been characterised using the field emission gun scanning electron microscope (FEGSEM) and electron dispersive X-ray spectroscopy (EDX) for microstructure and composition. The catalyst was used to study the decomposition of a model compound (e.g., carbetamide) using microwave radiation as well as conventional heating. Two kinds of trials were carried out constant power and constant temperature to observe the effect of variation of process parameters on the reaction rates. It was seen that the use of microwave heating enhanced the rate of decomposition compared to conventional heating in both scenarios. Attempts were also made to modify the composition of the catalyst and the support structure using polyvinylidene fluoride (PVDF) and carbon based additives (graphite and carbon black) to improve the microwave absorption characteristics. The combination of additive and PAN/PVDF mixtures has the potential to help in designing a suitable fabric support for catalyst that could be more receptive to microwaves, thereby helping to improve the energy efficiency of the process. Thorough investigation of dielectric properties and microwave absorption characteristics of the catalyst and support materials were performed independently. The heating rates of the meshes were monitored using an infrared thermal imaging camera. The absorption efficiencies of materials commonly used to build water treatment reactors such as polypropylene (PP), Fibreglass reinforced plastic (FRP), polyvinyl chloride (PVC), glass, PTFE, and fused quartz were assessed by subjecting them to constant microwave power experiments to ascertain their utility for making the reactor parts To take the successful lab scale results (100 ml) to scalable levels (80000 ml) for field trails, a new microwave reactor system was designed and tested. The cavity design was aided by multiphysics simulation of the electromagnetic field and temperature distribution inside the cavity. The model was created using COMSOL and provided valuable insight in making several design choices and improvements. The material data used in the model was determined both from our characterisation results and from corroborative literature data. The cavity itself was fully constructed using aluminium and the internal components were made using polypropylene and PTFE within the project timeline. The cavity was commissioned and initial testing at end user sites involved experiments measuring the rate of decomposition of carbetamide and other pesticides the results again emphasising that microwave treatment improves the reaction rates both from lab scale and in pilot scale water treatment situations in comparison to conventional treatment systems. This augers well for the generic applicability of the microwave assisted catalytic reactor system and its potential for the efficient treatment of contaminated water from hard to treat agricultural. Industrial, medical and defence waste/pollutants in future. An added advantage is that the developed microwave treatment system is mobile (on an ISO-container) and hence can reach the remote, contaminated site and treat it then and there rather than transporting the contaminated fluid to the treatment plant in a faraway location.

Iron oxide nanoparticles (IONPs) have been widely studied for a variety of applications, from biomedical applications (e.g., cell separation, drug delivery, contrast agent for magnetic resonance imaging and magnetically mediated energy delivery for cancer treatment) to environmental remediations (e.g., heavy metal removal and organic pollutants degradation). It has been demonstrated that IONPs can induce the production of reactive oxygen species (ROS) via Fenton/Haber-Weiss reactions which has been shown to be one of the key underlying mechanisms of nanoparticles toxicity. This inherent toxicity of nanoparticles has been shown to enhance the efficacy of traditional cancer therapies such as chemotherapy and radiation. In addition, the generation of ROS induced by IONPs has been also studied as advanced oxidation processes (AOP) for wastewater treatment. Recent research has also shown that exposure to an alternating magnetic field can significantly enhance the generation of ROS induced by IONPs. Moreover, the coatings of IONPs play an important role on the surface reactivity of nanoparticles since it can prevent the generation of ROS via Fenton chemistries at the surface of the nanoparticles. In this work, co-precipitated IONPs were functionalized with small molecules including citric acid, sodium phosphate, amino silane and dopamine. The impact of coating on surface reactivity of the as-synthesized particles was studied using methylene blue dye degradation assay under AMF exposure. With the coatings of these small molecules, the IONPs induced ROS generation was significantly decreased because of the dense surface coverage. To study the effect of polymeric coatings, a degradable poly (beta amino ester) (PBAE) polymer coating was synthesized with dopamine as an anchor to bind to nanoparticles. The surface reactivity of the particles was expected to be recovered once the polymer coating was degraded. Furthermore, the impact of non-degradable PEG-based polymer coating on surface reactivity via ROS generation was also investigated using methylene blue decolorization assay with the presence of AMF. The retention of surface reactivity of PEG-based polymer coated IONPs shows promise for cancer treatment. The application of IONPs as heterogeneous catalyst for organic contaminant degradation was investigated. Bisphenol A (BPA) was used as a model compound, and Fenton reactions were induced by IONPs with the presence of hydrogen peroxide and hydroxylamine as well as alternating magnetic field exposure. The kinetics of BPA degradation under water bath and AMF exposure at 37oC was also studied, and the results showed potential applications of IONPs for organic pollutants remediation.

M.Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology / Water contaminated with non-biodegradable organics is becoming increasing problematic as it has a hazardous effect on human health and the aquatic environment. Therefore, the removal of organic contaminants is of importance and an active heterogeneous Fenton catalyst is thus required. The literature indicates that a bimetallic oxide Fenton catalyst is more active than an iron oxide catalyst. This study focused on increasing the activity of iron-based Fenton catalysts with the addition of transition metals such as manganese, cobalt and copper and optimizing the preparation method. In this study, bimetallic oxide (Fe-Cu, Fe-Mn, Fe-Co) and monometallic oxide (Fe, Cu, Mn,Co) catalysts supported on silica SiO2 where prepared by incipient wetness impregnation. The total metal oxide contents were kept constant. The catalysts where calcined in two different ways, in a conventional oven and in a microwave. These catalysts were characterized with XRD, XPS and CV and were tested for the degradation of methylene blue dye at 27°C. The catalysts calcined in a microwave oven had a higher catalytic activity than those prepared in a conventional oven. The bimetallic oxide catalysts outperformed the mono- metallic oxide catalysts in the degradation of methylene blue. The Fe2MnOx prepared by microwave energy were the most active catalyst yielding the highest percentage of degradation of methylene blue dye (89.6%) after 60 minutes. The relative amounts of manganese and iron oxide were varied while keeping the total metal content in the catalyst the same. The optimum ratio of Fe to Mn was 1:7.5 since it yielded the most active catalyst. A 96.6 % removal of methylene blue was achieved after 1 hour of degradation. Lastly this ratio 1Fe:7.5Mn was prepared by varying different microwave power (600, 700 and 800 W) and irradiation time (10, 20 and 30 min). The optimum microwave power and irradiation time was 800W and 10 min with the methylene blue percentage removal of 96.6 % after 1 hour of degradation.