Synthesis, characterization, and functional evaluation of nanocomposites for water purification

The United Nations estimate that around 780 million people do not have access to clean and safe water and around 2.5 billion people do not have proper water sanitation. As a result, around 6–8 million people die each year due to water related diseases, such as cholera and dysentery, and disasters. As population increases the water problem will become more difficult to solve. Furthermore, climate change threatens to intensify water scarcity. The design of functional materials at the nanoscale offer unique solutions in molecular sorbents and catalytic systems that can develop into cost-effective solutions in water treatment by reducing the cost of the materials used and/or the energy consumption of the process. In this dissertation, the design, synthesis, characterization, and evaluation of function of nanocomposites is presented for (1) the efficient electrochemical generation of reactive oxygen species (ROS) for water treatment and sanitation using a novel composite of benzoyl-functionalized cotton cellulose and multi-walled carbon nanotubes (FC-MWCNT), and (2) a water permeable hydrogel with hyperactive metallic copper nanoparticles (NPs). The new FC-MWCNT nanocomposite, which utilizes functionalized cotton cellulose as a high-surface area support for pristine multi-walled carbon nanotubes, was characterized via scanning electron microscopy, infrared spectroscopy, thermographic analysis, Brunauer-Emmett-Teller surface area analysis, and cyclic voltammetry, exhibits high surface area (40 m2/g) and efficient electrocatalytic properties toward hydrogen peroxide. Furthermore, they were successfully applied toward the electrochemical degradation of methyl orange using only a -1.0 V potential, with optimal conditions at pH 3, 2.7 mM KCl, 0.219 M NaCl, in a treatment time of 4 minutes. The Cu-NPs nanocomposite, characterized by transmission electron microscopy, electron paramagnetic spectroscopy, energy-dispersive X-ray spectroscopy, dynamic light scattering, and inductively-coupled plasma-optical emission spectroscopy, were capable of chemoadsorbing arsenate, with a capacity of 5.3 g of As per gram of nanocomposite, and mineralizing it in large quantities out of water with little to no Cu leakage. By first coordinating Cu (II) ions to polymers capable of photopolymerizing into hydrogels, then reducing the ions to Cu (0), we were able to produce well dispersed, highly active Cu NPs that are capable of chemoabsorbing up to 90% of Arsenic from water in a wide range of pH levels. The development of functional nanocomposite materials offer new, more efficient methods for the purification of water. FC-MWCNT were synthesized and were capable of electrochemically degrading methyl orange. Furthermore, highly active Cu NPs dispersed and sequestered throughout water-permeable hydrogels were also synthesized and successfully removed 90% of As at a wide pH range