Biomass based carbon-carbon nanocomposite for water purification

Abstract

As the human population grows, our industrialization expansion and agricultural footprint increases as well, putting at risk the quality of freshwater bodies available due to contaminants as dyes, heavy metal ions, organic pollutants, etc. Several methods of water purification have been developed to satisfy the need for drinking water, but it is becoming harder to remove the wide variety of pollutants present now, due to their concentration and size, nano contaminants and emerging contaminants are a new potential threat. Porous carbon structures have been widely studied for their properties, such as large surface area, high porosity, high electrical conductivity, low thermal conductivity, among others, which makes them an interesting material for many areas, like supercapacitors, chemical sensors, energy storage and water purification, given that their properties can be tuned and that few materials have a good performance in all those attributes. Porous carbon structures, derived from biomass byproducts or polymers, have been used as meshes, membranes, or individual adsorbents for different pollutants. Here, the use of fruits’ pulp is proposed as a carbon source, as roughly 45% of cultivated fruits and vegetables are rejected before reaching consumers, which could render them an inexpensive raw material. Freeze drying of fruit pulp results in a very porous material, which can be pyrolyzed into a porous carbon material. To increase further the surface area and improve its adsorption properties, this project proposed the use of Chemical Vapor Deposition (CVD), for the catalytic-assisted growth of carbon nanostructures, in order to increase the removal of pollutants in water. In this case, affinity for methylene blue and copper ions adsorption were considered as the model systems to use. Our results show how the porous structure is maintained during the freeze-drying and pyrolysis process, as well as that catalyst particles can be formed in situ during pyrolysis by treating the freeze-dried fruit with iron containing precursor solutions. Due to time and quarantine limitations CVD experiments were not possible, thus the proposed final steps are discussed as expected results on the basis of the literature, and the steps to follow are presented, for when the experimental work can be resumed, as well as the possible future work.