Enhanced Photocatalytic Degradation of Congo Red Dye with Iron-Cobalt Oxide Nanoparticles: A Study on Sustainable Remediation Strategies for Aquatic Contaminants

Research Article

Austin J Biosens & Bioelectron. 2024; 9(1): 1048.

Enhanced Photocatalytic Degradation of Congo Red Dye with Iron-Cobalt Oxide Nanoparticles: A Study on Sustainable Remediation Strategies for Aquatic Contaminants

Noor Zada1*; Hamid Ullah2; Naveed Ullah2; Kashif Hussain2; Abbas Khan2; Fazal Habib2; Naseer Ul Haq2; Khalil Ullah2; Zaheer Ahmad3; Syed Muhammad Sohail4; Abdullah1; Roshni Begum1

1Department of Chemistry GDC Lal Qilla, Dir Lower KPK, Pakistan

2Department of Chemistry Government Postgraduate College Timergara, Lower Dir, Pakistan

3Department of Chemistry GDC Khanpur, Haripur, Pakistan

4Department of Chemistry GDC Badabera, Peshawar, Pakistan

*Corresponding author: Noor Zada Department of Chemistry Government Degree College Lal Qilla, Lower Dir, KPK-Pakistan. Email syednoorzada88@gmail.com

Received: February 28, 2024 Accepted: April 04, 2024 Published: April 11, 2024

Abstract

Transition metals (Iron and Cobalt), were used to synthesize bimetallic oxide nanoparticles through a wet chemical precipitation method. The Nanoparticles (NPs) were characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive X-rays (EDX), which revealed that they exhibited a mostly spherical, thick, dense, and agglomerated morphology. The EDX spectra confirmed the composition of the bimetallic oxide nanoparticles, with the presence of oxygen indicating their formation in the oxide form. These bimetallic oxide nanoparticles were then utilized as photocatalysts for the degradation of Congo red dye in aqueous medium under UV irradiation. The study investigated the influence of various parameters, including irradiation time, catalyst dosage, dye concentration, and pH of the medium, on the photocatalytic degradation of the dye. The results showed that Fe-Co oxide nanoparticles exhibited high photocatalytic activity, degrading 93% of the dye within 90 minutes. Furthermore, the degradation of the dye increased with longer irradiation times and higher catalyst dosages. Additionally, increasing the pH of the medium led to an enhanced degradation rate, with 80% of the dye degraded in 45 minutes at pH 10. However, the degradation rate decreased as the concentration of the dye increased.The findings from this study not only enhance our understanding of the photocatalytic properties of Iron-Cobalt oxides but also lay the foundation for further research endeavors aimed at optimizing and extending the applicability of these NPs in diverse environmental contexts. Ultimately, the outcomes of this study carry significant implications for advancing the field of environmental science and engineering, emphasizing the continued importance of exploring innovative technologies for pollution control and sustainable resource management.

Keywords: Congo red dye; Iron-cobalt nanoparticles; Wastewater treatment; UV irradiation

Introduction

Water, a vital and irreplaceable resource for daily life, development, and industrialization, faces a critical challenge due to the impact of rapid industrialization and population growth worldwide [1]. While industrial development is hailed as the backbone of a country's progress, it simultaneously poses a significant threat by releasing life-threatening wastes into aquatic systems [2]. Industries like printing, textile, papermaking, pharmaceuticals, food processing, and cosmetics contribute to this peril by discharging effluents laden with synthetic organic compounds such as dyes and pigments into water bodies [3,4]. These substances, characterized by large-scale production, high aromaticity, chemical stability, low biodegradability, toxicity, and carcinogenic nature, emerge as major environmental pollutants. The distinctive and easily observable colors of these dyes, even at low concentrations, render water highly detrimental to the environment and human health. The permanent coloration adversely affects animals' eyes and skin, leading to carcinogenic, mutagenic, and genotoxic disorders in humans, animals, and microorganisms [5]. Moreover, the presence of these dyes in water not only mars the river's beauty but also impedes sunlight penetration, affecting the photosynthesis of aquatic green plants. Consequently, water purification becomes a focal point of research and scientific interest, employing various treatment methods like adsorption, electrolysis, membrane filtration, chemical precipitation, physisorption, chemisorption, electrokinetics, ion exchange, and coagulation, aiming to address the pressing issue of water pollution caused by the discharge of organic dyes from industries. This attention to water purification is imperative due to the scarcity of fresh drinking water, making it a global concern that demands immediate and widespread solutions [6].

The realm of chemistry plays a pivotal role in comprehending the mechanisms and reactions involved in water pollution, offering diverse methodologies to address this issue and safeguard natural water resources [7]. Various techniques, including biological, physical, and chemical methods, are employed for treating water contaminated with toxic dyes [8,9]. Physical techniques such as adsorption, ion-exchange, coagulation, and membrane-filtration are commonly utilized for water treatment. However, these approaches have inherent limitations. Adsorption, for instance, is a sluggish process and proves inefficient in removing highly concentrated colors from polluted water [10]. Furthermore, physical techniques often suffer from incomplete dye degradation. Biological techniques, encompassing aerobic, anaerobic, and combined anaerobic-aerobic processes, leverage microorganisms for water treatment. While microorganisms play a vital role in these processes, they are less effective in degrading aromatic dyes with complex structures.

Over the past few years, the oxidation method, particularly the Advanced-Oxidation Process (AOP), has gained prominence in wastewater treatment [11-13]. This method involves the rapid formation of highly reactive free radicals capable of oxidizing and breaking down organic effluents. However, the short lifespan of oxidants poses a limitation.

An alternative, cost-effective approach involves harnessing solar light for wastewater treatment. Solar light, abundantly available on Earth at no cost, proves to be an excellent resource for degrading organic dyes present in polluted water. Nanomaterials, acting as photocatalysts, facilitate the photo-degradation of organic effluents, a process known as photocatalysis [14,15]. Heterogeneous photocatalysis, categorized as an advanced oxidation process [16], relies on metal oxide semiconductors absorbing UV or visible radiation to generate active species responsible for oxidizing organic compounds in wastewater. The efficacy of photocatalysis hinges on the adsorption of organic compounds onto the catalyst surface, a critical factor for enhancing the degradation rate. The success of this process is also contingent upon the surface area of the photocatalyst [17]. Utilizing a suitable photocatalyst and exploiting light radiation, this process initiates the generation of highly reactive hydroxyl (OH•) radicals. These radicals possess the capability to convert water pollutants into comparatively benign end products, such as CO2, H2O, and other inorganic ions [18,19], ensuring the safety of both humans and the environment. Photocatalytic degradation presents numerous advantages over traditional methods. It stands out as an efficient and straightforward instrumental technique, characterized by easily controllable operations and non-selective oxidation. Moreover, it proves cost-effective and can achieve the complete mineralization and degradation of synthetic organic dyes [20]. This process hinges on the presence of a semiconductor photocatalyst that activates upon absorbing photons. Notably, the photocatalyst can expedite the reaction without undergoing consumption [21]. Metal nanoparticles emerge as the most frequently employed photocatalysts, with their properties directly influenced by factors such as particle shape, size, geometry, and morphology [22]. Nanoparticles, characterized by their diminutive size below 100 nm, have garnered considerable attention due to their distinctive chemical and physical properties. Their potential applications span diverse fields, including medicine, solar cells, and nanodevices [23].

Congo Red dye belongs to the category of azo dyes and features two azo bonds (-N=N-) chromophores within its molecular structure. The inherent structural stability of this dye makes it notably toxic and resistant to biodegradation [24]. Widely employed in various industries, including cosmetics, paper, pharmaceuticals, chemicals, and textiles, Congo Red dye exhibits high stability in light, detergents, and water. The presence of aromatic amines in the dye's structure, responsible for carcinogenesis, poses a significant threat to both aquatic life and human beings [25].

The present research involves the synthesis of Iron-Cobalt bimetallic oxide nanoparticles (Fe-Co-NPs), as photo-catalyst, through a wet chemical precipitation method. The comprehensive investigation into the photocatalytic degradation of Congo red dye utilizing Iron-Cobalt oxides NPs holds paramount significance in addressing contemporary environmental challenges. The study not only may contribute valuable insights into the efficiency of advanced nanomaterials for pollutant remediation but also underscore the potential application of Iron-Cobalt oxides in sustainable water treatment processes. The significance lies in the urgent need to develop effective and eco-friendly strategies to mitigate the adverse impacts of industrial pollutants on aquatic ecosystems. Furthermore, the successful degradation of Congo red dye may signify a promising step towards the broader goal of developing efficient and scalable photocatalytic processes for wastewater treatment. As society continues to grapple with escalating concerns related to water pollution, this research paves the way for future advancements in the design and application of nanomaterials, offering sustainable solutions for environmental remediation and contributing to the collective efforts for a cleaner and healthier planet. The advantage of such catalysts is, if the band gap of one catalyst is high then the second one lowers its band gap and electron excitation. Moreover, the catalytic activity of the mixed bimetallic nanoparticles is much higher compared to single photo-catalyst. The morphology, structure, and elemental composition of the photo-catalyst were thoroughly examined using Scanning Electron microscopy (SEM), and energy-dispersive X-ray spectroscopy. The objectives of this study were; to develop a cost-effective and efficient photo-catalyst for the degradation of congo red dye. To mitigate water pollution caused by congo red dye and to investigate the influence of time, pH of the medium, amount of photo-catalyst, amount of recovered photo-catalyst, and dye concentration on the degradation of congo red dye.

Materials and Methods

Chemicals and Instrumentation

In terms of the chemicals and instrumentation utilized in this study, we sourced Manganese Chloride (MnCl4.2H2O), silver nitrate (AgNO3), sodium hydroxide (NaOH), nitric acid (HNO3), hydrochloric Acid (HCl), and sulfuric acid (H2SO4) from Frontier Chemical Company. Additionally, the Congo red dye crucial for the experiments was acquired from Danyal Trading Company located in Mingora, Pakistan.

For the morphological analysis of bimetallic oxide nanoparticles (NPs), we employed a JEOL JSM-5910 Scanning Electron Microscope (SEM). To delve into the elemental composition, both A-MWCNT-supported and unsupported bimetallic oxide NPs underwent scrutiny through energy-dispersive X-ray spectroscopy (EDX) utilizing a Model INCA 200/Oxford Instruments, based in Oxford, UK.

The investigation extended to the photodegradation study of CR in an aqueous medium. This particular aspect of the research involved the use of a UV–visible spectrophotometer. To delve into the structural aspects of the prepared catalyst, X-Ray Diffraction (XRD) patterns were meticulously collected. This process was facilitated by a PHILIPS X’ Pert PRO X-ray diffractometer employing Cu K-α radiation. The XRD pattern collection spanned from 10° to 80°, with an incremental step size set at 0.01°. These comprehensive methodologies were integral to the analytical processes undertaken in the study, providing a robust foundation for the subsequent findings and interpretations.

Preparation of Fe-Co oxides NPs

To synthesize Iron-Cobalt bimetallic oxide nanoparticles (Fe-Co oxides NPs), a round bottom flask containing 100 mL each of 0.1M CoCl2 and 0.1M FeCl3·3H2O solutions underwent a controlled addition of 0.2M NaOH drop by drop with constant stirring until reaching a basic pH of 10. The resulting mixture was then heated at 60°C for 2 hours under continuous stirring, leading to the formation of Fe-Co oxides nanoparticles in the form of a precipitate. After cooling, the NPs were filtered, washed with distilled water to remove any residual chemicals or impurities, and subsequently dried either under sunlight or using an oven before storage.

Photodegradation of Congo red dye by using Fe-Co oxides NPs

For the photo-degradation of CR dye, the prepared Fe-Co oxides NPs served as a photocatalyst under UV-light irradiation (254 nm, 15 W). An 80 ppm solution of CR dye was created, and 0.002g of Fe-Co oxides NPs were added to 20 mL of the dye solution in 50 mL beakers. After allowing for a 15-minute adsorption-desorption equilibrium in the dark, the mixture underwent UV-light exposure with constant stirring for varying time periods. Following UV-irradiation, the NPs catalyst was separated from the dye solution through filtration. The UV-Visible spectrophotometer was employed to monitor the photo-degradation of CR dye. Additionally, the influence of catalyst dosage and pH on the photo-degradation process was investigated. The catalyst dosage study involved varying amounts of catalyst while keeping other parameters constant, while the pH study explored the effects of different pH levels (4, 7, and 10) on the dye's photo-degradation. Acidic and basic solutions were prepared by adding HNO3 (0.1M) and NaOH (0.1M) dropwise to distilled water, respectively, before the dye solutions were prepared in these media.

UV-Vis Analysis

The photo-degradation study of the CR dye was carried out by using UV-Vis spectrophotometer. The % degradation of dyes was calculated by using the following formulas.

Degradation rate (%) =

Degradation rate (%) =

where Co stands for initial dye concentrations, C for the concentration of dye after sun-light irradiation, while Ao shows initial absorbance, and A is the dye absorbance after sun-light irradiation.

Results and Discussion

Characterization

In Fig. S1, Scanning Electron Microscope (SEM) micrographs of Fe-Co oxides nanoparticles are displayed at magnifications of 2500, 5000, and 10000, respectively. The Fe-Co oxide nanoparticles predominantly exhibit a spherical shape in the images. Throughout the micrographs, a consistent and homogeneous distribution of the nanoparticles is evident. Some particles appear in aggregated, agglomerated, and clustered formations, indicating certain degrees of nanoparticle clustering. Notably, the sizes of the nanoparticles remain nearly uniform, with no significant variation observed. This information provides valuable insights into the morphology, distribution, and size consistency of the Fe-Co oxide nanoparticles, essential for understanding their characteristics and potential applications. In Figure 1, the Energy-Dispersive X-ray (EDX) profiles of the Fe-Co oxide nanoparticles are also depicted. The long peaks observed in the figure correspond to the elemental composition of Iron (Fe), indicating the presence of iron in the nanoparticles. Conversely, short peaks represent the elemental composition of Cobalt (Co), confirming the existence of cobalt in the nanoparticles. The presence of oxygen peaks in the EDX profiles further validates that the Fe and Co nanoparticles are in their oxide form. This information is crucial for characterizing the chemical composition and oxidation state of the nanoparticles, providing insights into their properties and potential applications.