Abstract
The contamination of water by synthetic dyes has become a significant environmental issue, attracting increasing attention due to the harmful effects of dye-contaminated wastewater on aquatic ecosystems and human health. This has driven the development of advanced materials and technologies aimed at effectively removing dyes from water. Adsorption and catalytic degradation are two promising approaches for this purpose, offering both efficiency and sustainability. To achieve these goals, this work focuses on the synthesis of metal-organic frameworks (MOFs) using a controlled synthesis method and a sustainable synthesis technique, followed by their conversion into porous carbon materials for enhanced dye removal.A novel controlled synthesis method for MOF-235 was developed to increase the adsorption capacity for methyl orange. A yield of 166.7% was achieved compared to conventional methods. The synthesised MOF-235 exhibits a uniform octahedral shape with a narrow size distribution. Adsorption studies showed a maximum capacity of 1257.7 mg·g-1 , surpassing both the traditionally synthesised MOF-235 (477 mg·g-1 ) and other MOFs. Physical adsorption was confirmed as the primary mechanism, with optimal adsorption conditions identified.
In addition, Fe@C-350, a highly porous carbon adsorbent, was obtained by carbonisation of MOF-235 under an argon atmosphere and showed an increased surface area and pore size. This material showed advanced adsorption efficiency for methyl orange over a wide pH range with a maximum adsorption capacity of 1666.7 mg·g-1 . Kinetic analysis revealed a fast adsorption rate with a rate constant of 0.025 g·mg-1 ·min-1 , which can be attributed to the pore characteristics and abundant active sites. Remarkably, Fe@C-350 retained over 98% of its initial adsorption capacity after 10 regeneration cycles, confirming physical adsorption as the main mechanism. To further improve the removal efficiency of methyl orange while reducing the cost of material development, a carbon nanocomposite catalyst (PD-Fe@Cx) was synthesised using terephthalic acid from pyrolysed PET plastic waste, which can be used as a heterogeneous Fenton-like catalyst for methyl orange degradation. PD Fe@Cx exhibited optimal catalytic activity at a pyrolysis temperature of 350°C and effectively degraded methyl orange in the presence of hydrogen peroxide. The reaction parameters, including initial dye concentration, H2O2 dosage and pH, were optimised, with PD-Fe@C350 achieving 99.9% methyl orange degradation at a rate constant of 1.171 min-1 under optimal conditions. This approach not only utilises the properties of MOF carbons, but also promotes sustainability through the reuse of PET waste for environmental remediation.
In summary, this study makes an important contribution by developing highly efficient MOF-based porous carbon materials and PET-based catalysts for the effective removal and degradation of synthetic dyes and provides a sustainable solution to water pollution. Further work is needed to optimise the synthesis processes for industrial applications, in particular to improve material stability and scalability. In addition, the extension of this approach to other environmental pollutants will be crucial to advance the sustainability and efficiency of these materials in real-world applications.
| Date of Award | 15 Jul 2025 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Tao Wu (Supervisor), Xiang Luo (Supervisor) & Chenggong Sun (Supervisor) |