Covalent modification of graphene oxide: water remediation and carbocatalysis

The objective of this thesis is the application of new materials derived from the functionalization of graphene oxide in the fields of water remediation and CO2 utilization. Chapter 4.1 reports the synthesis and characterization of the graphene oxide (GO) modified with branched polyethyleneimine (GOPEI) material. This polymer was then functionalized with a fluorescent dye to monitor its purification through UV-vis spectroscopy. This process also allowed for a better understanding of the mechanisms underlying purification by microfiltration. By studying adsorption isotherms and formulating theoretical models, the kinetics, efficiency, and adsorption mechanism of GOPEI towards two pollutants, arsenic and lead, were discussed. Chapter 4.2 presents the study of the adsorption properties of a family of GO-based composites, covalently modified with three amino acids: L-Lysine, L-glutamic acid, and L-methionine (GO-Lys, GO-Glu, and GO-Met). Along with synthesis, the purification protocol was also improved to be faster and more efficient than previously reported, and their complete characterization was performed through XPS analysis. Finally, these materials were used as adsorbents towards a mixture of selected contaminants including pharmaceuticals, polymer additives, and dyes. Finally, in Chapter 4.3, a new synthesis of a GO-arginine composite (GO-Arg) and its utilization in carbon capture and utilization processes was reported. In the first part, the efficacy of CO2 fixation through the selective opening of epoxides to cyclic carbonates was demonstrated. The reported protocol was found to be applicable to a wide range of substrates, and its reusability was tested for up to 5 cycles. Furthermore, the application of this material in an ICCC process was discussed. It was shown that the material can capture CO2 from both high-purity atmospheres and low-concentration mixtures (such as the atmosphere) and converting it into cyclic carbonates when exposed to reaction conditions. The entire process was thoroughly studied and rationalized through computational and spectroscopic analyses.