Preparation and characterization of cross-linked graphene oxide-based composites for adsorption-based applications
Sabzevari, Mina 1988-
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Increasing activities in industry have resulted in wastewater generation that contains contaminants. Therefore, several methodologies have been developed to manage wastewater pollutants in which adsorption technology using graphene-based materials may offer an approach for efficient wastewater remediation. This Ph.D. thesis describes the synthesis and characterization of graphene oxide (GO)-based composites for adsorption-based applications. In the present study, chitosan (CTS) and aluminum ions (Al3+) as cross-linkers were utilized to enhance physical properties, mechanical performance and adsorption properties of GO by use of a solution-based method. The adsorption properties of samples were studied in solution and in the gas phase. Also, structural, morphological, physical, ion permeability, and mechanical properties of the GO and GO-based composites were studied using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), ion permeability determination and dynamic mechanical analysis (DMA), respectively. Mechanical properties of GO upon addition of cross-linkers were analyzed statistically by means of analysis of variance (ANOVA). Interaction of CTS and Al3+ ions with functional groups of GO sheets were supported by changes in surface charge of the GO sheets and spectroscopy techniques. SEM results showed that cross-linking of GO changes its porosity and layered morphology. The TGA results revealed that the GO-based composites exhibited a gradual weight loss which started at higher temperatures as compared with GO due to cross-linking effects. In addition, it was found that the swelling degree of GO reduced and was demonstrated to be more stable in water upon cross-linking. The sorption properties of GO in solution and the gas phase were found to remarkably improve upon formation of a GO-based composite. The results of Ion permeability tests indicated that GO composites had variable ion transport characteristics according to the changes in inter-layer spacing of GO sheets upon cross-linking. Additionally, the use of cross-linkers led to an increase in the mechanical properties of GO-based composites as compared with pure GO. ANOVA revealed that GO-based composites have a statistically significant enhancement in mechanical properties over pure GO. Therefore, GO-based composites prepared via cross-linking GO sheets have great potential for use as an alternative adsorbent and/or membrane for adsorption-based applications.
DegreeDoctor of Philosophy (Ph.D.)
CommitteeTabil, Lope; Szpunar, Jerzy; Oguocha , Ike; Fotouhi , Reza
Copyright DateJune 2019