Abstract

The huge surface area, redox characteristics, and magnetic properties of iron nanoparticles make them special. Iron sulphate (FeSO4) was used as a precursor to create iron nanoparticles, while Trigonella foenum-graecum was used as a reducing agent. There are a few more plant substitutes. Trigonella foenum-graecum is preferred over other plants because it is non-toxic, possesses exceptional antioxidant qualities, and stays stable at 60 °C when disturbed. The UV-Vis spectra showed the surface plasmon band (SPB) for iron nanoparticle formation at 430 nm. Iron nanoparticles with sizes in the range ( 23–77) nm and 50 nm, respectively, were visible in the pictures from the scanning electron microscope (SEM) and transmission electron microscopy (TEM).  Methylene blue, a model substance for contaminated water, was broken down by the produced iron nanoparticles at a wavelength of 663 nm. Additionally, its deterioration was investigated to gauge the photocatalytic performance of the samples. These results showed that iron nanoparticles had a significant level of photocatalytic activity, reaching up to 56% in a one hour.

Highlights:

1. Iron nanoparticles: large surface, redox, magnetic, photocatalytic properties.
2. Trigonella foenum-graecum: non-toxic, antioxidant, stable reducing agent.
3. Photocatalytic activity: 56% methylene blue degradation in 1 hour

Keywords: Degradation; Iron nanoparticle; Methylene blue dye; Water treatment

Introduction

Green synthesis has emerged as a practical and advantageous alternative to conventional physical and chemical synthesis methods for the creation of Iron nanoparticles. Hazardous chemicals, a lot of energy, and hazardous byproducts that are terrible for the environment and human health are commonly used in conventional processes. Conversely, microbes, plant extracts, and natural polymers are examples of biological agents that serve as stabilising and reducing agents in green synthesis [1,2]. This strategy adheres to the principles of green chemistry by limiting the use of hazardous chemicals and cutting waste [3, 4].

It is highly advantageous to use plant extracts in the green synthesis of iron nanoparticles because they include a multitude of phytochemicals, including flavonoids, phenolics, and alkaloids, which help with the formation and stabilisation of nanoparticles [5,6]. These proteins not only reduce iron ions to iron nanoparticles but also stabilise and cap them, improving their properties and preventing their aggregation [7, 8]. Furthermore, synthesis based on plants is scalable, cost-effective, and environmentally benign [9].

The successful production of iron nanoparticles (Fe NPs) using a variety of plant extracts, including as eucalyptus, tea leaves, neem, and aloe vera, has been reported in numerous studies; the properties that each extract adds to the nanoparticles differ based on the phytochemicals present [10, 11].The production of iron nanoparticles using microbial synthesis, which employs bacteria, fungi, and algae as biological factories, is another promising green technique [12]. The cell walls of microorganisms often serve as a natural template for the nucleation and stabilisation of nanoparticles, and they can convert metal ions to nanoparticles either intracellularly or extracellularly through metabolic processes [13].

This method can be utilised to reduce environmental toxicity and create highly biocompatible, functionalised nanoparticles that have a wide range of uses [14,15].

Green synthesis-produced iron nanoparticles have shown great potential in a variety of environmental applications, such as water treatment, soil remediation, and pollution control. Because of their high reactivity, large surface area, and eco-friendliness, they are ideal for removing organic contaminants, heavy metals, and pathogens from soil and water [16,17].

Despite these advantages, there are still challenges in improving the endurance and reactivity of the nanoparticles under different environmental conditions as well as in streamlining synthesis processes for industrial manufacture [18–21]. This effort aims to produce and characterize iron nanoparticles utilising a Trigonella foenum-graecum extract. These Iron nanoparticles' ability to effectively eliminate colored pollutants from water was demonstrated

Methods

2.1 Synthesis of iron nanoparticles using fenugreek extract as an oxidizing agent

First, the Trigonella foenum-graecum leaves that were bought from the market. It underwent air drying, mechanical molter crushing, and 60 μm mesh filtering. To finish, 100 millilitres of deionised water, 0.1 grammes of iron sulphate (FeSO4), and 0.1 grammes of plant leaves were combined. The conical flask was heated to 80 °C on a hot plate stirrer until it turned black. The production of nanoparticles was confirmed using a laser pointer for Tyndale scattering. These findings are displayed in Figure 1. The reduction of iron ions is what causes the colour change of the solution during the experiment. Trigonella foenum-graecum's fresh extract was brown in hue. Iron sulphate was added, and after ten minutes of continuous shaking at 0 °C, the solution's hue progressively turned deep brown. This suggested that Iron nanoparticles were forming.

To create Iron nanoparticles, the reducing agents in the Trigonella foenum-graecum extract aid in the reduction of Fe2+ ions. By acting as a capping agent, Trigonella foenum-graecum extract keeps them from clumping together. First, the Trigonella foenum-graecum leaves that were bought from the market. After being cleaned with water and let to air dry, it was crushed by a mechanical molter and filtered through a 60 micrometre mesh screen.

finally, the plant leaves (0.1 g) were added. One hundred millilitres of deionised water and 0.1 grammes of iron sulphate (FeSO4) were added. At 80 °C, the mixture was placed on the hot plate and stirred until a black hue appeared. The laser pointer for Tyndale scattering was based on the nanoparticle synthesis configuration. Figure 1 displays these findings. The process of decreasing iron ions is demonstrated by the colour shift of the solution during the experiment. Trigonella foenum-graecum's fresh extract had a dark colour. After adding iron sulphate and shaking the solution continuously at 0 °C for 10 minutes, the colour of the solution progressively changed to deep brown, indicating the creation of Iron nanoparticles.

The following details will be crucial to our study since the Trigonella foenum-graecum extract serves as a capping agent by stabilising the generated nanoparticles:

Figure 1.illustrates the stages of the synthesis of Iron nanoparticles:

A: Trigonella foenum-graecum leaves, B: Dried leaves of Trigonella foenum-graecum

C: Trigonella foenum-graecum powder, D: Tyndale effect in the Iron nanoparticles solution

Furthermore, TEM. Plasmon and SEM (FESEM, HITACHI, S-4160) were used to analyse the iron nanoparticles produced by Trigonella foenum-graecum. Using spectrophotometry, a total of n spectra was obtained for the investigation. We employed a light source with variable power (15 W and 30 W) and a fixed volume of 15 ml of iron nanoparticles for the degradation investigation. A 25 ml solution of the methylene blue dye was made with a 1 µg/ml concentration.

Result and Discussion

3.1 Characterization

The produced iron nanoparticles were examined using both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The pictures showed that the nanoparticles were uniformly distributed and ranged in size from 23 to 77 nm. Additionally, monodisperse nanoparticles with a sphere-like shape and seldom particle clusters were identified by the FESEM images. With a particle size of 50 nm, the TEM image displayed a similar occurrence. Figure 2 displays these findings.

Figure 2.shows the iron nanoparticles' SEM and TEM pictures.

3.2 Plasmon spectra for the characterization of iron nanoparticles

In agreement with other researchers, the plasmon resonance that appears at 315 nm signifies the production of iron nanoparticles [22]. Figure 3 shows this phenomenon.

Figure 3.Plasmon resonance demonstrations for iron nanoparticles

3.3 Application of iron nanoparticles to degrade methylene blue dye

The following ideal circumstances for the use of iron nanoparticles to degrade methylene blue dye were investigated. First, as shown in Figure 4, the ideal wavelength for methylene blue was determined to be 663 nm. Equation (1) was used to calculate the material's efficiency.

Efficiency%= 𝐶𝑜−𝐶𝑒 /𝐶𝑜 * 100 ……….1

where Ce is the equilibrium concentration of methylene blue dye (µg/ml), Co is the initial concentration of methylene blue dye (µg/ml).

Figure 4.shows that the maximum wavelength for methylene blue is 663 nm.

FThe calibration curve of methylene blue dye was done in the range (0.5-7 µg/ml) as can be seen in figure 5. The parameters were studied for optimum condition.

Figure 5.displays the methylene blue dye calibration curve.

The parameters were studied for optimum condition as following:

1. Examining the effects of employing various light intensities

Different light powers (15 watts and 30 watts) were used to accomplish the deterioration. At 30 watts and 2 millilitres of iron nanoparticles, the dye degradation was greater. These findings are displayed in Figure 6.

Figure 6.The degradation of methylene blue dye is demonstrated using two different LED light types: a 15-watt and a 30-watt LED light.

Because the proportion of deterioration is closely associated with the intensity of the light source, the percentage of methylene blue dye degradation design is 10.1% higher with 30-watt LEDs than it is with a light source (15 W).

2.Examining of the effects of applying varying amounts of iron nanoparticles

We find that the photodegradation percentages in each system under investigation are ideal for various regenerations based on the obtained data. The removal of oxygen and hydroxyl is made possible by either an increase in electron pairs or a rise in the number of distinct sites on the surface of the different photocatalysts. Dye photodegradation is increased on thermal insulation surfaces by a separate photo-degradation mechanism [23]. Figure 7 displays the effects

Figure 7.Illustrations of how various concentrations of iron nanoparticles degrade methylene blue colour.

3.Examination of the effects of applying varying amounts of methylene blue dye

As the concentration increased, the efficiency of degradation decreased for each catalyst. The reduced degradation rate at higher concentrations can be attributed to the high rate of dye molecule aggregation, the screening effect that slows light penetration, and the lack of photoactive sites brought on by increased dye molecule adsorption. where the percentage of crushing decreased by 3% to 56% at 35 ml and by 3% to 53% at 25 ml when the dye level was raised. These findings are displayed in Figure 8 [24].

Figure 8.illustrates how methylene blue dye degrades when varying dye quantities are used

Conlusion

Using plant extracts to turn iron salts into nanoparticles, this environmentally friendly process provides a long-term substitute for more traditional techniques. The generated iron nanoparticles effectively broke down methylene blue dye from contaminated water at a wavelength of 663 nm. In the UV-visible spectrum, the iron nanoparticles' plasmon spectra showed a distinct peak at 350 nm. Iron nanoparticles are spherical in shape and fall between 23 and 77 nm in size, based on images from SEM and TEM. The production of iron nanoparticles has been clearly shown by studies, and a few phytochemicals included in the plant extract act as stabilising and capping agents for the produced iron nanoparticles.

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