In a recent article published in Scientific Reports, researchers introduced a novel approach to efficiently removing polycyclic aromatic hydrocarbons (PAHs) from milk samples. The approach utilizes a magnetic chitosan/molybdenum disulfide nanocomposite.
PAHs are a group of environmental pollutants known for their harmful effects on human health, making their removal from food products crucial.
Study: Employing a magnetic chitosan/molybdenum disulfide nanocomposite for efficiently removing polycyclic aromatic hydrocarbons from milk samples. Image Credit: Dedy_SW/Shutterstock.com
Background
PAHs are a group of organic pollutants commonly found in the environment due to various anthropogenic activities such as industrial processes, vehicle emissions, and incomplete combustion of organic materials.
Due to their carcinogenic and mutagenic properties, these compounds pose a significant risk to human health and the environment. PAHs can accumulate in food products, particularly dairy products like milk, through environmental contamination or direct exposure during processing and storage.
Traditional methods for PAH removal from food matrices often involve complex extraction techniques or chemical treatments, which may be costly, time-consuming, and environmentally harmful.
Therefore, there is a growing need for innovative and sustainable approaches to eliminate PAHs from food products efficiently, ensuring consumer safety and regulatory compliance.
The Current Study
The magnetic chitosan/molybdenum disulfide nanocomposite was synthesized using a straightforward chemical method. Chitosan, with a low molecular weight and 80% degree of deacetylation was first dissolved in acetic acid solution.
Molybdenum trioxide and urea were then added to the chitosan solution under constant stirring to form a homogeneous mixture. Subsequently, thioacetamide was introduced as a reducing agent to convert molybdenum trioxide to molybdenum disulfide.
The resulting mixture was further treated with glutaraldehyde to crosslink the chitosan matrix and enhance the stability of the nanocomposite.
The morphology and structure of the magnetic chitosan/molybdenum disulfide nanocomposite were characterized using transmission electron microscopy (TEM) and field-emission scanning electron microscopy (FE-SEM).
TEM analysis provided insights into the size and distribution of Fe3O4 nanoparticles within the nanocomposite, while FE-SEM imaging allowed for the visualization of the surface morphology and composition of the nanocomposite. Energy-dispersive X-ray spectroscopy (EDX) was employed to confirm the elemental composition of the nanocomposite.
A series of adsorption experiments were conducted to assess the efficiency of the nanocomposite in removing PAHs from milk samples. Standard pyrene, phenanthrene, and anthracene solutions were prepared in HPLC-grade methanol and spiked into raw milk samples.
The nanocomposite was then added to the PAH-spiked milk samples at optimized dosages, and the mixture was agitated for a specified contact time. After adsorption, the concentration of PAHs in the solution was analyzed using high-performance liquid chromatography (HPLC) to determine the removal efficiency of the nanocomposite.
The adsorption kinetics of PAHs on the magnetic chitosan/molybdenum disulfide nanocomposite were investigated using pseudo-second-order kinetic models.
By monitoring the changes in PAH concentrations over time, the adsorption rate constants and equilibrium times were determined.
The kinetic data were fitted to the pseudo-second-order model to elucidate the adsorption mechanisms and predict the equilibrium adsorption capacity of the nanocomposite for different PAH compounds.
Results and Discussion
The TEM analysis revealed a well-dispersed structure of Fe3O4 nanoparticles with an average diameter of 10-12 nm within the magnetic chitosan/molybdenum disulfide nanocomposite.
The TEM images confirmed the formation of a core-shell structure, where molybdenum disulfide was successfully deposited on the surface of Fe3O4 nanoparticles.
FE-SEM further supported these findings, showing a uniform distribution of molybdenum disulfide on the Fe3O4 surface. EDX analysis confirmed the presence of carbon (C), oxygen (O), nitrogen (N), sulfur (S), iron (Fe), and molybdenum (Mo) elements in the nanocomposite, validating the successful synthesis of the composite material.
The adsorption experiments demonstrated the high efficiency of the magnetic chitosan/molybdenum disulfide nanocomposite in removing PAHs from milk samples.
Optimal removal efficiencies were achieved for phenanthrene, anthracene, and pyrene, with maximum absorption capacities of 217 mg/g, 204 mg/g, and 222 mg/g, respectively.
The sorbent dose, initial PAH concentration, pH, and contact time were systematically optimized to enhance the removal efficiency. The equilibrium adsorption process followed the Freundlich isotherm model, indicating favorable adsorption behavior on the nanocomposite surface.
The adsorption kinetics of PAHs on the magnetic chitosan/molybdenum disulfide nanocomposite were investigated using the pseudo-second-order kinetic model. The experimental data exhibited excellent fitting to the pseudo-second-order model, suggesting a chemisorption mechanism and indicating an equilibrium time of approximately 150 minutes.
The calculated rate constants further supported the efficient adsorption of PAHs on the nanocomposite surface, highlighting the rapid removal of contaminants from the milk samples.
Conclusion
In conclusion, the magnetic chitosan/molybdenum disulfide nanocomposite shows great promise as an efficient sorbent material for removing PAHs from food products, particularly milk samples.
Chitosan's environmentally friendly nature, combined with the high adsorption capacity of molybdenum disulfide, makes this nanocomposite a sustainable and effective solution for addressing PAH contamination.
Further research and optimization of this nanocomposite could lead to its widespread application in food safety and environmental protection.
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