| dc.description.abstract | Pharmaceuticals are a recent category of pollutants that have had a substantial influence on both the environment and public health. The presence of Pharmaceuticals in groundwater, seawater, and wastewater treatment plants have been extensively covered. Emerging contaminants (ECs) such as organic dyes are among the top organic pollutants that need remediation. The main objective of this thesis is to develop and produce a 2D environmentally friendly adsorbent materials for the purpose of removing ECs (such as Atenolol-AT, Ciprofloxacin-CPF, Gemfibrozil-GMF, Diclofenac-DFN, Carbamazepine-CB, Ibuprofen-IBU, Methyl Orange-MeO, Methyl Red-MeR, and Rhodamine B-RD) from water. This thesis involved the synthesis of five green adsorbents using environmentally friendly methods. The adsorption performance of these adsorbents was then assessed against these ECs.
For the purpose of water treatment applications, five adsorbents were selected based on key criteria such as high specific surface area, physical and chemical stability, regeneration ability, and adsorption capacity. In addition, their eco-friendly synthesis processes contributed significantly to their selection. Carbon-based adsorbents, including porous graphene and activated carbon, were chosen due to their outstanding hydrophobicity, low toxicity, significant specific surface area, and good regeneration ability. These properties ensure effective removal of pollutants from water. Furthermore, their chemical stability makes them an ideal adsorbent materials for water treatment. Covalent Organic Frameworks (COFs) with imine linkages were selected for their superior stability compared to other linkages. These COFs possess the highest specific surface area among the considered adsorbents, making them suitable candidates for water treatment applications in this thesis work. Transition Metal Dichalcogenides (TMDs) exhibit exceptional chemical stability, making them suitable for various environmental conditions. TMDs have a large surface area, providing numerous adsorption sites. They also display excellent electronic properties, such as high carrier mobility and direct bandgap transitions, which can be advantageous for adsorption processes. In conclusion, these adsorbents were selected for their eco-friendly synthesis processes and their ability to effectively address the key criteria required for efficient water treatment applications. Their unique properties make them promising candidates for the focus of this research.
The first part of this thesis developed a greener PG synthesis method. This thesis presents initial findings on efficiently oxidising graphite using ferrate (VI) compounds via encapsulation. Encapsulated ferrate (VI) compounds were used to achieve green graphite oxidation and resolve the ferrate (VI) oxidation capability conundrum by reducing graphene oxide (GO) synthesised from this near green approach with Vitamin-C to obtain greener PG. The greener PG was tested against MeO, MeR, RD, CPF, AT, IBU, and CB to demonstrate its adsorption potential. High PG dosages achieved over 90% Removal Efficiency (R.E) against MeO and IBU. Overall R.E was higher for greener PG than commercially purchased PG for all the seven ECs.
The second part of this thesis investigated the room-temperature synthesis of modified 2D imine-linked covalent organic framework-COF (M-COFLZU1) with a specific surface area (SSA) of 1889 m2/g. Small angle X-Ray Diffraction showed that M-COFLZU1 is crystalline, and batch tests showed that the adsorbent performed well even in difficult conditions, eliminating several ECs - CPF, CB, GMF, DFN, MeO, and MeR with a 96% R.E. COF-MG, another eco-friendly adsorbent, was synthesised using M-COFLZU1 and greener GO. SSA increased significantly for COF-MG compared to greener PG. The batch test results for the COF-MG showed that monolayer physisorption mainly contributed to removal of ECs. COF-MG's recyclability showed more reuse cycles for efficient EC removal. The combination of M-COFLZU1 and greener GO encourages the development of many green composites or matrices for ECs removal.
The third section of the thesis developed a non-carbon-based 2D adsorbent material named Molybdenum disulfide nanoflowers (MoS2 NFs). This material was synthesised utilising an environmentally benign hydrothermal method and tested for EC adsorption, including MeO, MeR, RD, and CPF. The high SSA of 185.5 m2/g MoS2 NFs achieved a 96% R.E. for RD and an 85% R.E. for CPF. Several morphological and phase identification analyses confirmed the material's high crystallinity and its NF structure. The batch test showed that enthalpy-driven adsorption is exothermic, physisorption-controlled, and fast-kinetics. The MoS2 NF's ability to regenerate more than four times proved its adsorption potential.
A porous Green Activated Carbon made from Aubergine peels (Green AuGAC), via a green synthesis, was tested as an adsorbent for CPF removal, in the fourth section of this thesis. The activation of Biochar Carbon derived from Aubergine peels was confirmed by several characterisations. This activation process involved salt intercalation followed by thermal activation at low temperature. The study found that Green AuGAC's BET SSA was 72.7 m2/g. Green AuGAC was tested for CPF removal, highlighting its potential as an environmentally friendly adsorbent. The lowest dosage of Green AuGAC yielded an R.E. over 85%. Green AuGAC showed fast kinetics with physisorption and chemisorption-controlled adsorption. Further thermodynamic simulations proved the exothermic nature of enthalpy driven and physisorption regulated adsorption. The findings suggested that the aubergine peel has the potential to be used as a precursor for synthesising several eco-friendly adsorbents.
In summary, this thesis contributed to the development of eco-friendly adsorbent materials by synthesising them via novel green approaches. It also offers a foundation for guiding future research in the constantly evolving field of cleaner and more sustainable environments. | en_GB |
