Assessment of Green-Synthesized Fe₃O₄ Nanoparticles for Wastewater Treatment

INTRODUCTION
Wastewater is increasing at an alarming rate, due to various reasons, the most important of which is the discharge of waste directly into water sources, and household, mechanical and agricultural waste directly into water bodies. Most of these wastes are rich in phosphorus and carbon, which causes a phenomenon known as over-nutrients. Over-nutrients occur due to the excessive proximity of nutrients within the aquatic body, which helps in the spread of the eutrophication phenomenon [1-3]. Removal of major toxins such as suspended solids, bio-oxygenase depletion (BOD), additives (organic and inorganic) and coliforms is the most objective goal of wastewater purification. This requires more advanced treatment technologies because water pollutants have increased, water resources have decreased in the world and the need for water has increased [4]. Various adsorption mechanisms such as electrostatic interaction, surface complexation, and ion exchange govern pollutant removal using Fe₃O₄ nanoparticles [5]. Green-synthesized magnetic nanoparticles have demonstrated efficient removal of heavy metals and organic contaminants [6,7]. Oil, mill water, hospital wastewater and household sewage are all pollutants that have been shown to be able to be removed using nano-treatment [8]. Nanomaterials have proven their ability to break down fats, remove dyes and precipitate suspended particles due to their high reactivity and unique properties [9]. The working principle of nanocoagulants is to form large aggregates (clusters) of small particles. These particles are often removed by simple filtration or sedimentation. This preparation will reduce and break up the natural matter and turbidity in the water [10]. Coagulation goes through three stages including clot formation, particle destabilization, and finally particle aggregation. Natural coagulants aggregate particles and aggregates by adsorption onto their surfaces, followed by charge neutralization or particle locking. There are four coagulation mechanisms that occur within the particle aggregation process: double layer compression; net agglomeration; adsorption and charge neutralization; and adsorption and particle attraction [11]. Various nano metal oxides have been used in water treatment, including nano aluminum and nano iron [12]. However, nanomaterials, being new in use, remain dangerous if they are not tested. Therefore, I am turning to using nanomaterials manufactured in a green way that are safe for the environment [13,14]. 
Environmentally friendly nanomaterials can be manufactured from natural sources such as bacteria and fungi, but the most important safe source for green nanotechnology is plants, which have proven their efficiency in creating effective and low-cost water treatments, and the resulting sludge is low in biodegradability [14-17]. The aim of the present study is to green synthesis of C-Fe₃O₄ from (Cinnamomum spp. plants) as a natural nano-coagulant in wastewater treatment.

MATERIALS AND METHODS
Treatment of plant
Cinnamomum spp.were collected and attended according to the method of [18].

Materials created by plants 
After being purchased and sanctified with distilled water, dried cinnamon bark was allowed to air dry in a shaded area. After drying, it was ground into a fine powder and kept for later use in sterile plastic containers. 

Making an aqueous extract of the plant Cinnamomum spp
In accordance with the procedure outlined by Irshaid and Mansi [11], 50 grams of powdered cinnamon bark were combined with deionized water in a 1:10 ratio and heated for 30 minutes at 70 °C while being constantly stirred. After filtering, the extract was kept at 4 °C.

Synthesis of iron oxide nanoparticles
Iron salts (FeCl₂·4H₂O and FeCl₃·6H₂O) were dissolved in distilled water in a 1:2 molar ratio and heated to 70°C. The cinnamon extract was added dropwise under stirring. Sodium hydroxide was added to reach pH 9–11, and the mixture was stirred for 1–2 hours. The resulting black precipitate was centrifuged, washed with water and ethanol, and dried in an oven [19]. 
These biosynthesized nanoparticles were later characterized using standard techniques such as UV–Vis spectroscopy for optical confirmation, and XRD for determining crystalline structure. Microscopy tools like FE-SEM were employed to visualize morphology and size distribution [20].

Collecting water samples
Samples of treated water were collected from the wastewater in Barakia in Najaf Governorate in Iraq, in 4 iterations from the main sedimentation tank using different types of clean containers.

Water Sample Measurements
Temperature, pH, and electrical conductivity were measured using a multispectral spectrometer, while turbidity was measured using a turbometer. All the above-mentioned instruments were calibrated in the laboratory before measurements began.
Total dissolved solids, chemical oxygen demand (COD), and total organic carbon were measured according to the methods described in the American Public Health Association (APHA) [21].
To evaluate the efficiency of natural NPs, a jar test was conducted on water samples whose initial properties. The pre-prepared NPs at room temperature underwent lime agitation to ensure homogeneity before use.
The methodology included the following steps:
Volume and Rapid Mixing: One liter of water sample was taken, the nanoflake was added, and the mixture was treated with a rapid mix at 150 rpm for one minute to provide initial mixing.
Slow Mixing and Settling: The mixing speed was reduced to 50 rpm and continued for 20 minutes to induce flocculation, followed by a static clarification and settling phase lasting 15 minutes.
To optimize performance, varying concentrations of the nanoflake, ranging from 0.5 to 1 ppm, were tested to determine the optimal dosage based on the lowest residual contaminant level. The study also included measuring the effect of pH across a wide range (3 to 10) to determine the most effective pH in the coagulation process.

Statistical analysis
The data obtained underwent one-way analysis of variance (ANOVA), followed by the least significant difference (LSD) test to determine the substantial differences between the means.

RESULTS AND DISCUSSION
Detection of active components in Cinnamomum spp. plants
Table 1 presents the phytochemical screening results of the aqueous extract of Cinnamomum spp., revealing the presence of several bioactive compounds. Positive results were obtained for terpenes, tannins, terpenoids, flavonoids, phenols, coumarins, and alkaloids. In contrast, the extract tested negative for glycosides, resins, and saponins. 

Identification of C-Fe₃O₄ NPs
The morphological properties of the nanoparticles produced using Cinnamomum spp. (FE-SEM) was used to examine and it reveals the of spherical structure with nonuniform distribution. The surface morphology showed rough textures, likely due to the presence of bio-organic compounds from the plant extract on the nanoparticle surface. as in the Fig. 1. Based on SEM analysis and particle size estimation using **ImageJ software**, the nanoparticles exhibited a size distribution ranging from 13 to 20 nm, with an average diameter of approximately 16.5 ± 3 nm. The size was estimated by measuring over 50 individual particles using the scale bar provided in the SEM image Fig. 2. The clear lattice fringes indicated their crystalline nature as in Fig. 3. XRD patterns displayed distinct diffraction peaks at 2θ values matching the cubic spinel structure of Fe₃O₄. XRD patterns displayed distinct diffraction peaks at 2θ values matching the cubic spinel structure of Fe₃O₄ .XRD patterns displayed distinct diffraction peaks at 2θ values of )30.1°, 35.5°, 43.1°, 53.4°, 57.0°, and 62.6°(, which correspond to the (220), (311), (400), (422), (511), and (440) planes of the cubic spinel structure of Fe₃O₄ , respectively. These peaks were identified based on comparison with the standard JCPDS card No. 19-0629. UV-visible spectra of Cinnamomum spp. extracts and C-Fe₃O₄ NPs are shown in Fig. 4. UV–Vis spectroscopy confirmed the formation of C-Fe₃O₄ NPs by the presence of a characteristic absorption band around 280 nm, which is typically associated with Fe³⁺–O²⁻ charge transfer transitions, as reported in earlier studies [17,18].

Experience treating organic and inorganic pollutants
The results of the tests for treating organic and inorganic pollutants showed that an equilibrium state was reached after 24 hours of treatment, after which the absorption was constant. When equilibrium was achieved, the clear solution was reanalyzed to determine remaining contaminants and removal rates.
The current study focused on the possibility of using C-Fe₃O₄ nanoparticles prepared from the aqueous extract of the Cinnamomum spp plant in treating polluted water, and its presence in wastewater was detected. The results demonstrated the possibility of removing these pollutants by exposing manufactured C-Fe₃O₄ nanoparticles at different concentrations and for different periods of time.
The data presented in Tables 2 and 3 demonstrate that pollutant removal efficiency increased progressively with time and concentration. At a concentration of 0.5 mg/L (Tables 2 and 3, moderate improvements were observed after 24 hours, particularly in EC and TOC. The nano-treatment achieved the highest EC removal (66.1%) and TOC reduction (46.8%) compared to the plant extract and the nano–extract mixture.
At the higher concentration (1 mg/L) (Table 3), removal efficiencies improved significantly. After 24 hours, the nano-treatment exhibited superior performance, achieving 86.9% TOC removal, 68.5% EC reduction, and 66.8% TDS removal. The nano–extract mixture also showed substantial efficiency (78.6% TOC removal), whereas the plant extract alone demonstrated comparatively lower but consistent removal rates.
The increase in efficiency with time indicates enhanced adsorption and surface interaction processes. Furthermore, the higher concentration (1 mg/L) promoted greater pollutant binding capacity, particularly for organic carbon removal. The slight variations in pH across treatments remained within acceptable environmental ranges, indicating treatment stability.
Overall, C-Fe₃O₄ nanoparticles synthesized via plant extract exhibited the highest remediation capability, particularly for TOC removal after 24 hours at 1 mg/L. Many studies have been conducted to determine the effectiveness of low-cost adsorbents such as peat, ash and betonies in removing organic materials from wastewater by adsorption method. Studies showed that an equilibrium time of 5 and 16 hours was needed for adsorption of organic matter on peat, fly ash and bentonite, respectively. Phenol adsorption on peat and bentonite has been well studied. Using a standard solution with a concentration of 1 mg/L, it was found that peat, ash, and bentonite adsorbed 46.1%, 41.6%, and 42.5% of phenol, respectively [22]. Activated carbon (in granular and powder form) is also one of the most widely used adsorbents. It has a good ability to adsorb many organic and inorganic pollutants, although it has many disadvantages.

Activated carbon is very expensive and reactivation produces additional effluents and losses
Large: 10-15% of the absorbent material. Also, previous studies used aquatic plants such as flower Nile algae or others have demonstrated high potential in treating inorganic pollutants [23].
This opened the way for many researchers to find cheaper alternatives such as bottom ash, fly ash, fly ash-wallastonite, [24] lignite, peat, soil, wallastonite, wallastonite-china clay (1:1) to be used as alternatives that have proven their efficiency in removing many pollutants. The Lepironia plant was also studied to remove PAHs from wastewater using the batch flow system. The results showed that the removal potential reached 79.9%. Also, the use of the tropical plant and Eleocharis ochrostachys in treating oil pollutants, PAHs, both proved an effective treatment rate that reached 71.91 % respectively [25]. Overall, plant-mediated synthesis of Fe₃O₄ nanoparticles represents a promising strategy for sustainable wastewater treatment applications [26,27].

CONCLUSION
The physicochemical parameters of wastewater (pH, EC, TDS, and TOC) were effectively reduced using C-Fe₃O₄ nanoparticles, plant extract, and their 1:1 mixture. Removal efficiency increased with both exposure time and concentration. The best performance was achieved using nano C-Fe₃O₄ at 1 mg/L after 24 hours, where removal percentages reached: pH: 12.1%; EC: 68.5%; TDS: 66.8%; TOC: 86.9%. These findings confirm the high efficiency of plant-mediated C-Fe₃O₄ nanoparticles in treating organic and inorganic pollutants, outperforming the plant extract alone and the combined nano extract mixture. The results support the applicability of green-synthesized nanoparticles as an effective and environmentally compatible wastewater treatment strategy.

ACKNOWLEDGEMENTS
The researchers extend their sincere thanks and appreciation to the Department of Environmental Sciences at the College of Science, University of Kufa, for the support and resources provided to complete this research.

CONFLICT OF INTEREST
The authors declare that there is no conflict of interests regarding the publication of this manuscript.