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" Functional Graphene-Based Nanohybrids and Aerogels for Water Treatment and Emerging Contaminant Removal "
Masud, Arvid Mohammad
Aich, Nirupam
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Latin Dissertation
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| Language of Document
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English
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| Record Number
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1111321
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TLpq2497958903
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| Main Entry
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Aich, Nirupam
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Masud, Arvid Mohammad
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| Title & Author
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Functional Graphene-Based Nanohybrids and Aerogels for Water Treatment and Emerging Contaminant Removal\ Masud, Arvid MohammadAich, Nirupam
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| College
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State University of New York at Buffalo
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| Date
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2021
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| student score
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2021
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| Degree
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Ph.D.
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| Page No
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160
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| Abstract
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Many emerging micropollutants evade conventional wastewater treatment processes and contaminate the receiving water bodies. Pharmaceuticals and personal care products (PPCPs) and per- and polyfluoroalkyl substances (PFASs) are two such emerging micropollutants which are mostly aromatic and fluorinated aliphatic organic compounds, respectively. These two emerging micropollutants pose environmental and human health risks either through bio-accumulating in the food chain or contaminating the source of drinking water. Engineered nanomaterials with multifunctionalities and surface reactivity have the potential to treat these emerging micropollutants detected at trace concentration in water. Two-dimensional carbonaceous nanomaterial graphene and its derivatives have emerged as a platform for pollutant removal from water due to their abilities to adsorb both organic and inorganic pollutants, abilities to support metal nanoparticles on planar surfaces, high charge transfer properties that can help catalysis for pollutant degradation, and abilities to create hierarchical porous structures. The first part of this dissertation investigates the performance of a graphene-based nanohybrid, namely reduced graphene oxide-nanoscale zero-valent iron (rGO-nZVI NH), in removing PPCPs and PFASs from water. The rGO-nZVI NH synergistically performed adsorption and advanced oxidation against PPCPs and PFASs. PPCPs have different chemical structures, hydrophobicity, and charge across different therapeutic classes that affect their removal from water. Therefore, the efficiency of rGO-nZVI NH for PPCP removal was tested against a mixture of diverse PPCPs representing different therapeutic classes. Furthermore, one of the features of emerging micropollutants are their trace level prevalence in the aquatic environment; therefore, the performance of rGO-nZVI NH was investigated against sub-ppm level concentrations of PPCPs. The rGO-nZVI NH performed as an adsorbent and heterogeneous Fenton catalyst to remove PPCPs from water and yielded better performance (26-91% more removal) than the parent nanomaterials, rGO and nZVI. The chemical properties of PFASs are dictated by differences in their chain length and functional head groups. Therefore, the removal efficiency of rGO-nZVI NH for PFAS removal was tested with a mix of PFASs with different chain lengths and head groups. The rGO-nZVI NH resulted in better removal of longer chain PFASs compared to the shorter chain ones. To identify the PFAS degradation products after rGO-nZVI NH mediated treatment, liquid chromatography with high-resolution mass spectroscopy (LC-HRMS) was performed for non-target detection of any unknown PFAS byproducts. This resulted in identification of two unique partially degraded PFAS-iron complexes. This further enabled the identification of possible PFAS degradation pathways initiated by rGO-nZVI NH. The second part of this dissertation focused on removing barriers for practical application of graphene-based nanomaterials for water treatment. One of the most important challenges for practical application of graphene (or other nanomaterials) in water treatment are the risk of their release into treated water due to their colloidal stability. To resolve this issue, graphene-based aerogels have emerged which are macroscopic structures with hierarchical porosity and can retain the contaminant adsorption capacity of nano-scale graphene. These aerogels can be easily separated from water minimizing the risk of graphene release. However, control over the bulk design of graphene-based aerogels is required for their integration into geometrically optimized modular treatment devices. This dissertation is one of the first systematic efforts to use scalable synthesis methods for graphene-based aerogel fabrication with control over the bulk design. At first, a 3D printed mold assisted freeze casting method was used to synthesize graphene-polydopamine (G-PDA) aerogel. PDA cross-linked the graphene sheets reinforcing the material network within the aerogel, and thus, provided mechanical stability in water. Furthermore, PDA enabled the conjugation of catalytic nanomaterials (e.g., nZVI, TiO2) within the G-PDA aerogel making the aerogel catalytically reactive against contaminants. Secondly, a direct ink writing (DIW) approach was adopted to directly 3D print graphene-polydopamine-bovine serum albumin (G-PDA-BSA) aerogel with architectural flexibility. The bio-inspired polymers, PDA and BSA, provided the graphene-based ink with required viscoelasticity and shear thinning property for DIW printability. In both fabrication methods, the bio-inspired polymers modified the graphene with additional functional groups confirmed by the change of their surface charge. Both G-PDA and G-PDA-BSA aerogels were tested against a wide range of contaminants including heavy metals, dyes, organic solvents, and oil. Furthermore, a filtration study with a 3D printed fit-for-design G-PDA-BSA aerogel integrated in a 3D printed bottle cap filter was demonstrated as a proof of concept for point-of-use filter.The dissertation showed the prospect of a graphene-iron nanohybrid in treating PPCPs and PFASs through multiple synergistic removal mechanisms and revealed the scope for further tuning graphene-based nanohybrids for targeted removal of emerging micropollutants. Furthermore, this dissertation spearheaded the research on scalable fabrication of shape controllable graphene-based aerogels that pave the way for their practical application in modular treatment devises.
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Environmental engineering
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Nanoscience
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Water resources management
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