INTRODUCTION:
Iron oxide nanoparticles have attracted intensive research interest because of their important applications in cancer therapy, drug delivery, magnetic resonance imaging (MRI) and waste water treatment1. Many recent studies have indicated the potential of iron nanoparticles for environmental remediation. Nanoscale materials such as nano adsorbents, nano catalysts, nano filtration and nano biocides such as metal and metal oxide nanoparticles are currently being employed for remediation of water and wastewater pollutants. Among these metallic nanoparticles, iron nanoparticles have promising advantages that can combat environmental pollution2. The interest in nanoscale zero valent iron in environmental remediation is increasing due to reactivity of nanoscale iron having a large surface area to volume ratio 3,4.
The biosynthesis of iron nanoparticles of different sizes and shapes has been reported using bacteria, fungi and plant extract. Green synthesis of nanoparticles is very cost effective, environment friendly and non-toxic.
Aerva lanata known as polpala (treatment for renal disease) is aprostrate to decumbent sometimes erect herb found throughouttropical India as a common weed in fields and wasteland. The plantis useful for curing diabetes. It is anthelmintic, demulcent and ishelpful in Lithiasis, Cough, Sore throat and Wounds5. The plant hasbeen reported to possess anti-inflammatory and nephroprotectivein rats6.
There are a couple of successful studies in synthesizing Fe3O4-NPs by using plant extract. For instance, fruit extract of Artemisia annua7, leaf extract of Perilla frutescens8, Tridax procumbens9, caricaya papaya10, peel extract of plantain11 and also seed extract of grape proanthocyanidin12. The production of iron nanomaterials such as metallic iron and oxide of iron via more convenient greener route, is a great step forward in the development of nanomaterials.
MATERIAL AND METHODS:
a. Materials:
Ferric chloride (FeCl3. 6H2O) were purchased from Merck Chemical Reagent Co. Ltd. India. All glassware was washed with sterile distilled water and dried in a hot air oven before use. The flower of the Aerva lanta was collected from our college premises, Tirunelveli District, Tamil Nadu during winter season.
b. Collection of flower extract:
Aerva lanta were collected, washed and cleaned with triple distilled water and dried with water absorbent paper. Then it was cut into small pieces with an ethanol sterilized knife and crushed with mortar and pestle dispensed in 10 mL of sterile distilled water and heated for 10-15min at 80°C in Erlenmeyer flask. The extract was then filtered using Whatmann’sNo.1 filter paper. The filtrate was collected in a clean and dried conical flask by standard sterilized filtration method and was stored at 4°C for further experiments.
c. Synthesis of Iron oxide nanoparticles:
During the synthesis of Magnetite nanoparticles, 50ml of Aerva lanta flower extract was taken and boiled to 60-80 °C using a stirrer-heater. 5 grams of Ferric chloride was added to the solution as the temperatures reached 60°C. This mixture is then boiled until it reduced. This paste was then collected in a ceramic crucible and heated in an air heated furnace at 400 °C for 2 hours. Black coloured powder was obtained and this was carefully collected and packed for characterization purposes. The material was mashed in a mortar-pestle so as to get a finer nature for characterization.
d. Characterization techniques:
Scanning electron microscopy (SEM) analysis of synthesized metal oxide nanoparticles was done using a Quanta FEI 450 SEM machine. Powder X-ray diffraction was performed using a X-ray diffractometer, Shimadzu, XRD-6000 with CuKα radiation λ = 1.5405 Ĺ over a wide range of Bragg angles (20o ≤ 2θ ≤80o). Fourier transform infrared spectroscopic measurements were done using Shimadzu, spectrophotometer. UV–vis spectrum of metal oxide nanoparticles was recorded, by taking 0.1 ml of the sample and diluting it with 2 ml deionized water, as a function of time of reaction using a Schimadzu, 1601 spectrophotometer in the wavelength region 300 to 700 nm operated at a resolution of 1 nm.
RESULT AND DISCUSSIONS:
a. UV-DRS Analysis of Nanoparticles:
UV- Diffuse Reflectance spectroscopy has proved to be a very useful technique for study in metal oxide nanoparticles because the peak positions and shapes are sensitive to particle size. The color change of the particles (Fig.1) indicated the formation of iron oxide nanoparticles. UV-visible spectroscopy analysis was done in the range of 200-800 nm and the maximum absorbance was observed at 211 and 259 nm regions for the formation of iron oxide nanoparticles due to the excitation of surface plasmon vibrations. The shorter UV absorption wavelength indicated that the nanoparticles did not form aggregation.
Fig:1 UV-DRS of Iron oxide nanoparticles
b. FT-IR Spectral Studies:
In order to determine the functional groups and identify their role in the synthesis of metal oxide nanoparticles, FT-IR analysis was performed. FT-IR studies of Aerva lanta flower extract reveals the presence of phyto constituents like alcohol, aldehydes and amine which were the surface active molecules stabilized the nanoparticles and this phytochemicals have interacted with the metal such as iron surface and aids in the stabilization of iron oxide nanoparticles.
The absorbance spectra band at 1627.9, 1402, 1318, 1041, 532.3, 447.4 cm-1 are more characteristic and mainly responsible for the bio-reduction of iron ions. The strong absorption band at about 532.3 cm-1 and 447.49 cm-1 are due to Fe‒O stretching vibration and bending vibration for the Fe3O4 nanoparticles. The structural changes in FT-IR spectra indicated that the capping and stabilization of metal oxide nanoparticles via the coordination with OH, -CH, C=O. Thus, IR spectroscopy confirmed that the carbonyl group from amino acid residues and protein has the stronger ability to bind metal indicating that proteins could possibly form a layer covering the metal nanoparticles (i.e., capping agent ) to prevent agglomeration and there by stabilize the medium. This suggests that the biological molecule of flower extract of Aerva lanta could possibly perform dual functions of formation and stabilization of metal oxide nanoparticles.
Fig: 2 FT - IR Images of Iron oxide Nanoparticles
c. XRD Pattern of Metal oxide nanoparticles
The X-Ray powder diffraction pattern of the synthesized nanopowder from Ferric chloride in the presence of flower extract of Aerva lanta was recorded on the X-ray diffractometer using Cu (kα) (λ = 1.5415 x 10-10 ) radiation operating at 40 kv and 30 mA with 2θ ranging from 10 – 80 ̊ .
The XRD pattern with the diffraction peaks at 38.06, 44.23, 64.40 and 74.33 corresponding to the (111), (200), (220) and (222) facets of the face centered cubic crystal structure. The broadening of the Braggs peaks indicates the formation of nanoparticles. In addition to the Bragg peaks, unassigned peaks were also observed suggesting that the crystallization of bio-organic phase occurs on the surface of the iron oxide nanoparticles. The average crystalline size of the synthesized Fe3O4 nanoparticles was calculated to be 38 nm using De-bye Scherrer equation.
Where D is the crystallite size of ferric oxide nanosheets, λ represents wavelength of x-ray source 0.1541 nm used in XRD, β is the full width at half maximum of the diffraction peak, K is the Scherrer constant with value from 0.9 to 1 and θ is the Bragg angle.
Fig: 3 XRD Images of Iron oxide Nanoparticles
d. SEM Analysis
The powdered sample was analyzed for the structure and morphology of the synthesized iron oxide nanoparticles using SEM at different magnification levels including 10µm and 50µm (Fig.4). SEM images revealed that the synthesized metal oxide nanoparticles were aggregated as irregular sphere shapes with rough surfaces. The morphology of the nanoparticles mostly appeared to be a porous and spongy.
Fig: 4 SEM Images of (a) Iron oxide
e. EDS Analysis of Metal Oxide Nanoparticles:
The elemental composition of Fe NPs was studied using EDS. As can be seen from the Fig. 5, the predominant peaks were of iron (Fe), Oxygen (O) and Carbon (C). The signals for C and O were mainly due to the different phytochemicals present in extract. The signal for oxygen also confirms the fact that iron oxide nanoparticles have been synthesized. The weight percent (wt %) of nanoparticles was measured to be 25.52% for Fe, 35.99% for O and 36.98% for C. The high Fe loading enables easy magnetic recovery of as-prepared nanoparticles. Some minor loading from silica (Si) was also observed. It would be arising from the plant material. As cited from relevant literature, the iron content of Fe NPs synthesized during the study is found to be comparable with iron nanoparticles obtained from other plant materials.
Fig: 5 EDX Images of Iron oxide Nanoparticles
CONCLUSION:
In this study, magnetite nanoparticles were synthesized successfully by a simple and green approach using the polpala flower extract without utilizing any chemical-reducing agent and stabilizer. Based on the XRD analysis studied, a high purity crystalline of magnetite Fe3O4-NPs was prepared and the particle size found to be around 38nm. FTIR spectroscopy showed the involvement biomolecules present in the flower extract of polpala, which were verified in the synthesizing process of magnetite Fe3O4-NPs. The formation of magnetite Fe3O4-NPs was confirmed due to the noticeable absorption peaks at 532.3 and 447.49 cm-1. SEM result revealed the morphology of the synthesized magnetite Fe3O4-NPs. Most of the particles possessed irregular spherical shapes with rough surfaces. The non-toxic green synthesized magnetite Fe3O4-NPs are expected suitable to be employed in various fields of applications, especially in biomedical applications.
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Received on 24.01.2018 Modified on 20.02.2018
Accepted on 21.03.2018 © AJRC All right reserved
Asian J. Research Chem. 2018; 11(2):459-462.
DOI:10.5958/0974-4150.2018.00083.4