Recovery from Waste Streams: Working Towards a Sustainable Future

The overall aim of this project was to utilise green chemistry methodology to capture potentially harmful, toxic or valuable compounds from wastewater.
Novel mesoporous materials, Starbon®, prepared from naturally abundant polysaccharides, have demonstrated significant potential as adsorbents for the uptake of a range of dyes and phenols. Through the use of different polysaccharide starting materials (starch and alginic acid) and different preparation temperatures, six materials were produced. The resulting materials were characterised by techniques including: solid-state NMR, nitrogen porosimetry, FT-IR, x-ray photoelectron spectroscopy and electron microscopy. The experimental results revealed that the materials exhibited high efficiency to remove dyes and phenols from aqueous media due to their high mesoporous nature. The adsorption process was described well by the Langmuir, Freundlich and Dubinin-Radushkevich isotherms. Thermodynamic analysis of the results indicated that adsorption was a physical process.
Investigations into the capture of palladium from liquid waste and also greener methods of supported nanoparticle formation were also carried out. Biosorption of palladium by alginic acid and seaweed was highly successful, resulting in nanometer sized palladium deposits within the adsorbent. The catalytic activity of these materials was successfully demonstrated through the use of Heck and Suzuki reactions.
Preliminary work exploring the first use of living plants to recover palladium from water and in situ production of catalytically active palladium nanoparticles also is presented. This novel process eliminates the necessity for nanoparticle extraction from the plant and reduces the number of production steps compared to traditional catalyst palladium on carbon. These plant catalysts have demonstrated high catalytic activity in a range of C-C coupling reactions, outperforming traditionally used palladium catalysts.