| dc.description.abstract |
The increasing concern for environmental sustainability has led to enhance interest in
developing efficient, sustainable, and cost-effective methods for wastewater treatment.
As industrialization and urbanization accelerate, the complexity and diversity of
pollutants present in industrial, agricultural, and municipal wastewater have rendered
traditional water purification methods insufficient. Conventional methods such as
coagulation, filtration, and chemical oxidation are often ineffective against a wide
range of contaminants, including Persistent Organic Pollutants (POPs), dyes, heavy
metals, and pharmaceutical residues. These pollutants pose significant threats to
ecosystems and public health, necessitating the development of advanced water
treatment technologies. Among the emerging solutions, photocatalysis has garnered
significant attention due to its ability to harness solar or artificial light energy to drive
oxidative and reductive reactions, leading to the degradation of harmful substances into
non-toxic by-products, primarily water and carbon dioxide. Cerium Oxide (CeO2), a
rare earth metal oxide, has been recognized for its outstanding photocatalytic and
catalytic properties, which are mainly attributed to its redox behavior, high Oxygen
Storage Capacity (OSC), and its ability to generate Reactive Oxygen Species (ROS).
In particular, intrinsic ability of CeO2 to absorb UV light and generate electron-hole
pairs under irradiation has shown promise in decomposing organic pollutants.
However, to achieve higher efficiency under visible light crucial for practical
applications given the broad solar spectrum CeO2 needs to be modified through doping
or by creating composite materials with enhanced photocatalytic performance.
This research work investigates the photocatalytic activity and magnetic properties
of pure CeO2 nanoparticles and its doped variants with Europium (Eu), Gadolinium
(Gd), Activated Carbon (AC), and nanofiber composites. The goal of this research is to
enhance the UV light driven photocatalytic efficiency of CeO2 while simultaneously
improving its magnetic properties. Doping with Eu and Gd was chosen based on their
electronic configurations and proven ability to shift bandgap of CeO2 toward the UV
light region. Europium and gadolinium, both rare earth elements, can introduce
intermediate energy states within band structure of CeO2, thereby promoting the
utilization of UV light photons for more efficient pollutant degradation. Additionally,
their presence enhances charge separation by preventing the rapid recombination of
photo-generated electron-hole pairs, a common issue that limits the photocatalytic
performance of undoped CeO2. This improved charge separation leads to a higher
quantum yield of reactive oxygen species such as hydroxyl radicals, which are highly
effective in breaking down organic molecules in wastewater. Our research revealed that
both Eu- and Gd-doped CeO2 showed a significant increase in the degradation rate of
organic dyes such as Rose Bengal (RB) dye under UV light irradiation, compared to
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pure CeO2. The magnetic properties of doped CeO2 are of particular interest due to
their potential application in the magnetic separation techniques. By inducing the
ferromagnetism through doping, the photocatalyst can be easily recovered from the
treated water via an external magnetic field, reducing operational costs and preventing
secondary contamination. Our findings demonstrate that Eu- and Gd-doped CeO2
exhibit enhanced magnetic properties, facilitating their separation from solution
post-treatment without compromising their photocatalytic efficiency.
The incorporation of Activated Carbon (AC) and nanofiber composites further
amplifies the photocatalytic activity and stability of the CeO2 based materials.
Activated carbon, known for its large surface area and excellent adsorption
capabilities, serves as a support material that enhances the adsorption of pollutants
onto the catalyst surface, thus increasing the availability of contaminants for
photocatalytic degradation. Moreover, activated carbon helps in trapping the
photo-generated electrons, further mitigating electron-hole recombination and
boosting photocatalytic efficiency. Nanofiber composites, on the other hand, contribute
to structural integrity and mechanical stability, which are critical for the longevity of
the photocatalyst. The nanofiber framework not only offers additional surface area but
also improves the dispersion of CeO2 particles, thereby facilitating better light
absorption and reaction kinetics. The hybridization of CeO2 with nanofibers and
activated carbon offers a multifunctional material with superior performance in
wastewater treatment applications. In conclusion, the development of CeO2 based
materials doped with europium, gadolinium, and integrated with activated carbon and
nanofibers represents a significant advancement in the field of photocatalysis. These
multifunctional materials not only exhibit superior photocatalytic efficiency under UV
light but also offer the practical advantage of magnetic recovery, making them highly
suitable for sustainable and scalable wastewater treatment solutions. This research
highlights the potential of tailored photocatalytic materials to meet the growing
demand for clean water and contribute to global efforts toward environmental
protection. |
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