Greener synthesis of biopolymer-inorganic nanocomposite beads and membranes for use in water purification

Abstract: In South Africa, the unavailability of clean drinking water is a life-threatening problem, especially in the rural areas. Millions of people living in rural areas rely on water directly from the source (surface and groundwater) for drinking, cooking and other domestic purposes without any prior treatment. These sources of water are known to be affected by contaminants from untreated wastewater, industrial effluent, agricultural runoffs and domestic waste. The exposure of humans to these polluted water bodies results in infection and waterborne diseases which sometimes result in death. This has a direct consequence to the productivity of the people living in these communities and has cost implications to the government. This study was aimed at determining the potential pollutants present in drinking water sources in Lochiel, a small community in the Mpumalanga province, eastern part of South Africa, and to develop efficient and cost effective materials (beads and membranes) that could be used in the rural communities to provide safe and clean water for consumption. The application of adsorption materials (e.g. in the form of beads) and filtration materials (e.g. membranes) has attracted great interest in water purification. This is because they have several advantages over the conventional methods. These advantages include but are not limited to low capital and operations costs, low energy requirements (especially when chemically modified) and ease of operation. In this study chitosan (CTs) was chosen to prepare novel and environmentally benign nanocomposite materials either in the form of beads or flat sheet using greener solvents. In an attempt to prepare biopolymer-ceramic nanofiltration composite membranes, small amounts of multiwalled carbon nanotubes (MWCNTs) (5 wt%) and alumina (Al) (20 wt%) were added to CTs in pH controlled aqueous media near room temperature. The resulting nanocomposite was found to readily form insoluble beads...M.Sc. (Chemistry