Smart Photocatalytic Degradation of Textile Dyes Using Doped Visible-Light Titanium Dioxide Nanoparticles for Water Purification

Project Abstract

Smart photocatalytic degradation of textile dyes using doped visible-light titanium dioxide nanoparticles for water purification presents an efficient approach to mitigate dye-contaminated effluents from textile industries through enhanced photocatalytic activity under visible light. This study synthesizes doped TiO2 nanoparticles with non-metal and metal co-dopants (e.g., nitrogen, carbon, iron, and copper) to tailor band gaps, extend light absorption into the visible spectrum, reduce electron-hole recombination, and improve catalytic performance in aquatic environments. A green sol-gel and hydrothermal synthesis route was employed to produce uniformly dispersed doped TiO2 nanostructures with controlled crystallinity, surface area, and pore distribution. Comprehensive characterization using X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and BET surface area analysis confirmed phase stability in anatase/rutile mixtures, narrowed band gaps, and successful incorporation of dopants at strategic lattice sites, which enhance charge separation and dye adsorption. The photocatalytic efficacy was evaluated against a suite of representative textile dyes, including azo, anthraquinone, and triphenylmethane classes, under simulated solar and visible-light irradiation. Kinetic studies revealed pseudo-first-order degradation behavior with rate constants significantly higher than pristine TiO2 under identical conditions, while luminescence quenching and electrochemical impedance spectroscopy indicated substantially reduced recombination rates and improved charge transport. Mechanistic insights were gleaned from radical scavenging experiments, electron spin resonance, and intermediate identification via high-performance liquid chromatography-mass spectrometry, illustrating a multistep pathway driven by photoexcited doped TiO2 generating reactive oxygen species such as hydroxyl radicals, superoxide anions, and singlet oxygen. Adsorption experiments demonstrated that dopants modulated surface charge and hydrophilicity, enabling enhanced dye uptake—particularly for anionic dyes—thereby accelerating degradation kinetics. The study further investigates the influence of operational parameters, including catalyst loading, initial dye concentration, pH, ionic strength, and presence of natural organic matter, on photocatalytic performance and long-term stability. Reusability tests over multiple cycles showed minimal loss of activity, indicating robust catalyst durability suitable for practical deployment. A pilot-scale evaluation using a packed-bed reactor under continuous flow conditions demonstrated consistent dye mineralization with satisfactory degradation efficiencies and minimal leaching of dopants. Life cycle assessment and techno-economic analysis were conducted to compare the environmental footprint and cost-effectiveness relative to conventional treatment methods, highlighting noteworthy reductions in energy consumption and chemical usage when leveraging visible-light-driven doped TiO2. This research provides a validated framework for the design of visible-light-active photocatalysts with tunable properties that address the persistent challenge of dye pollution in water bodies, offering a scalable, sustainable solution for textile wastewater treatment. The findings elucidate the optimal dopant combinations, synthesis parameters, and operational conditions necessary to achieve high degradation efficiency, mineralization, and catalyst stability in real-world settings.

Project Overview

What This Project Is About

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The project explores using specially prepared titanium dioxide nanoparticles that are doped with other elements to work effectively under visible light to break down dyed fabrics in water. It looks at how this photocatalytic process can clean water by removing harmful dyes with sunlight or ordinary indoor light.

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The Problem It Addresses

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Textile dyes commonly end up in water sources, causing color, toxicity, and ecological harm. Many catalysts only work under UV light, which is a small portion of sunlight. This project aims to create a visible-light–driven solution that is efficient, affordable, and safer for the environment.

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Objectives of the Project

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1. Design and synthesize doped TiO2 nanoparticles that respond to visible light.
2. Test their ability to degrade common textile dyes in water under visible light.
3. Evaluate how different dopants affect performance and stability.
4. Investigate the influence of light exposure, dye type, and water conditions on degradation rates.
5. Assess potential byproducts for safety and environmental impact.

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What You Will Do Step by Step

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1. Review literature on photocatalysis and visible-light activation.
2. Synthesize doped TiO2 nanoparticles in the lab.
3. Characterize the materials (sizes, structure, optical properties).
4. Set up dye-water tests under visible light and measure dye concentration over time.
5. Analyze data to determine degradation efficiency and kinetics.
6. Compare dopant types and study reusability of the catalyst.
7. Assess environmental safety of residues and possible byproducts.

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Expected Outcome

An effective, visible-light–driven dye degradation system using doped TiO2, with data on performance, optimal dopants, and practical considerations for real-world water purification.