International Proceedings of Chemical, Biological and Environmental Engineering, V0l. 101 (2017) DOI: 10.7763/IPCBEE. 2017. V101. 9 One Pot Green Synthesis and Characterization of Trimetallic Oxide CuCrNiO NPs Using Eryngium Campestre Leaf Extract Zahra Vaseghi 1, Omid Tavakoli 1 and Ali Nematollahzadeh 2 1 School of Chemical Engineering, College of Engineering, University of Tehran, Iran 2 Chemical Engineering Department, University of Mohaghegh Ardabili, P. O. Box, 179, Ardabil, Iran Abstract. Trimetallic oxide CuCrNiO nanoparticles (NPs) were successfully synthesized from their precursor salts including CuSO4.5H2O, Cr(NO3)3.9H2O, and Ni(NO3)2.6H2O in a facile and green method using aqueous leaf extract of Eryngium campestre as reducing and stabilizing agents. NPs were characterized using UV-vis spectroscopy, FTIR, EDX, XRD, and FESEM showing that trimetallic oxide NPs were synthesized in the form of nanoplates with the thickness of 18.73 nm and crystallite size of 17.39 nm. Keywords: green synthesis, trimetallic NPs, aqueous leaf extract, characterization 1. Introduction In recent years, production of NPs through green route has received considerable attention from researchers all over the world. Choice of solvent, reducing, and stabilizing/capping agent are three main criteria which should be taken into consideration in the green synthesis of NPs [1]-[3]. Typically, in green synthesis approach the reducing agents can be applied from two main categories of microbial (microorganism mediated) and phyto (plant mediated) [1], [4]. Plant mediated synthesis of NPs has some advantages including increased synthesis rate, enhanced monodispersity and stability of NPs, and decreased requirement for complex treatment in comparison to microbial synthesis using bacteria, fungi, yeast, and algae [1]. The idea of producing trimetallic NPs has been originated from the improved characteristics and functionality of these NPs compared to monometallic and bimetallic NPs [5]. Trimetallic NPs have been produced recently by green method using aqueous extracts of plants [6], [7]. Eryngium campestre is a plant belonging to Apiaceae family growing mostly in North of Iran. Generally, phytochemical screening of plants indicates the capability of them to take part in the reduction reaction of heavy metal ions and precipitating them as NPs [8], [9]. The content of flavonoids and phenolic compounds in E. campestre has made it a proper candidate to be involved in bioreduction of metal ions and capping of the produced NPs. In this study, aqueous leaf extract of E. campestre was used as a green and environmentally benign source for producing trimetallic oxide CuCrNiO NPs. The biosynthesized trimetallic NPs were characterized using UV-vis spectroscopy, FTIR, EDX, FESEM, and XRD. 2. Materials and Methods All chemicals including CuSO4.5H2O, Ni (NO3)2.6H2O and Cr (NO3)3.9H2O were purchased from Merck (Germany). Double-distilled water was used throughout the experiments for preparation of solutions and other purposes. The plant was collected from north of Iran. Corresponding author. Tel.: +98-21-6111 2187; fax: +98-21-6649 8984. E-mail address: [email protected]. 62 2.1. Preparation of Plant Leaf Extract First, fresh leaves of E. campestre were collected. The leaves were washed with tap water to remove impurities and then were washed twice with double-distilled water before being shade dried for seven days. The dried leaves were grinded with household mill till a fine powder was achieved. Leaf extract was prepared by adding 5 g of plant's leaf powder into 100 mL distilled water. The mixture was then sonicated for 15 minutes at 300 W. After wards, it was filtered with Whatman no.1 filter paper. The resulting filtrate was used as plant extract for green synthesis of trimetallic nanoparticles. 2.2. Green Trimetallic Oxide NP Synthesis The method involves simultaneous reduction of precursor salts (CuSO4.5H2O, Ni (NO3)2.6H2O and Cr (NO3)3.9H2O) with plant extract. Typically, leaf extract with definite ratio (metal salt-to-leaf extract ratio was set at 1.32) was added to 0.01 M solution of the salts. The reaction was performed in 250 mL Erlenmeyer flasks at appropriate temperature (40oC). After completion of the reaction (approximately within 296 min) and allowing the reaction mixture to cool down to room temperature, the produced trimetallic oxide NPs were washed several time with distilled water followed by ethanol to remove impurities, and then separated by centrifugation. Finally, the NPs were kept in vacuum oven at 45oC for further use. 2.3. Characterization of Trimetallic Oxide NPs Surface plasmon resonance of the bio-synthesized trimetallic oxide nanoparticles was measured by UV/Vis spectrophotometer (Nanolytik® NanoSpec 2 spectrophotometer). Fourier transform infrared spectroscopy (FTIR spectroscopy RXI, Perkin Elmer, USA) was used to study the functional groups responsible for bioreduction of the metal ions. The chemical composition of decapped NPs was measured by Energy Dispersive X-ray Spectroscopoy (EDX). X-ray diffractometer (XRD) with Cu Kα radiation using the Philips powder diffractometer system (λ = 1.54060 nm, 40 Kν and 30 mA) in the range of 10-80º with 2 º/min scanning rate was used to characterize the crystallinity of the trimetallic nanoparticles. In addition, the morphological observation of the trimetallic nanoparticles was carried out by field emission scanning electron microscopy (FESEM, MIRA3TESCAN-XMU). 3. Results and Discussion The UV-Vis spectra of the trimetallic oxide NPs produced using E. campestre leaf extract is shown in Figure 1 a. The presence of a peak at 220 nm indicates the formation of trimetallic oxide NPs due to excitation of surface plasmon resonance which is further confirmed by color change of reaction mixture from clear brown to colloid brown suspension (Figure 1 b, c). Fig. 1: (a) UV-vis spectra of trimetallic oxide CuCrNiO NPs, (b) E. campestre leaf extract, and (c) trimetallic oxide NPs EDX analysis was used to identify the elemental composition of the green trimetallic oxide NPs produced using E. campestre leaf extract. As is apparent from Figure 2, the presence of Copper, Chromium, Nickel, and Oxygen has been proved in the trimetallic structure. However, the composition of these elements 63 was different compared to the feed ratio (1:1:1). Meanwhile, the share of Oxygen was outstanding (approximately 70% by atomic percent and 40% by weight percent) which is probably due to absorption from reaction medium during the process of bioreduction. Also, while Copper and Chromium synthesis yield was considerable amount (30.23 and 26.29% by weight percent) Nickel was synthesized in little quantity (3.96% by weight percent). O K 1500 CrL 1000 CuL NiL CrK 500 CuK CrK NiK NiK CuK 0 keV 0 5 10 Element Int Error W% A% O 381.2 3.1745 39.52 70.19 Cr 281.8 0.7264 26.29 14.37 Ni 18.4 0.7822 3.96 1.92 Cu 101.8 0.7822 30.23 13.52 Total 100.00 100.00 Fig. 2: EDX spectrum of trimetallic oxide CuCrNiO NPs. Produced NPs were further characterized by FTIR analysis to identify the possible biomolecules in the leaf extract which were responsible for the reduction of metal ions and trimetallic oxide NPs formation. FTIR spectra of trimetallic oxide CuCrNiO NPs as well as E. campestre aqueous leaf extract are depicted in Figure 3. The presence of some major peaks at the FTIR spectrum of E. campestre leaf extract such as those occurred in 3397, 1644, and 742 cm-1 are assigned to O–H stretching of alcohols and phenols, C═O groups of flavonoids, phenolic acids, and C–H stretching of aromatic compounds. While the peaks at 3312, 2922, 1648, 1438, 1264, and 1066 cm-1 in trimetallic oxide CuCrNiO NPs correspond to O–H stretching of alcohols and phenols, C–H stretch of alcohols and phenols, C═O groups of flavonoids, phenolic acids, C═C of aromatic rings, C–OH stretching vibrations and C–O bonding, respectively. Therefore, it may be concluded that polyphenolic compounds presents in the leaf extract including phenolic acids and flavonoids are mainly responsible for the bioreduction of metal ions and stabilization/capping of the produced trimetallic oxide NPs. Fig. 3: FTIR spectra of aqueous E. campestre leaf extract and trimetallic oxide CuCrNiO NPs 64 Morphology of the produced NPs was studied by field emission scanning electron microgram (FESEM). The images of FESEM are depicted in two resolutions of 500 and 200 nm as shown in Figure 4. As is apparent from the images, trimetallic oxide NPs are synthesized in the form of nanoplates crossing each other with different angles. The thickness of these nanoplates calculated from image J software was found to be 18.73 nm. Fig. 4: FESEM image of trimetallic oxide CuCrNiO NPs at the resolution of (a) 500 nm, and (b) 200 nm. X-ray diffraction (XRD) was used to study the crystalline nature of NPs. XRD pattern presented broad peak at around 36o indicating that the produced NPs have very small crystallite size. Debye-Scherrer equation was used to calculate the crystallite size of trimetallic oxide CuCrNiO NPs from the width of XRD peaks [10]. The calculated crystallite size for NPs obtained using E. campestre leaf extract was 17.39 nm which is very near to the thickness of nanoplates obtained using the FESEM (Figure 5). Fig. 5: XRD pattern of trimetallic oxide CuCrNiO NPs 4. Conclusion The present study reveals that the aqueous leaf extract of E. campestre can be successfully used as reducing as well as capping/stabilizing agent for the one pot green synthesis of trimetallic oxide CuCrNiO NPs. In fact, synthesizing metal or metal oxide NPs using green sources is a good alternative to chemical synthesis mainly due to the use of environmentally benign materials and elimination of the use of toxic chemicals by restricting the hazards imposed to the environment.