1334 ISSN 0036-0244, Russian Journal of Physical Chemistry A, 2016, Vol. 90, No. 7, pp. 1334–1337. © Pleiades Publishing, Ltd., 2016. Microwave Assisted Green Synthesis of Silver Nanorods As Catalysts for Rhodamine B Degradation 1 Tharini Jeyapragasam* and R. Sayee Kannan Department of Chemistry, Thiagarajar college, Madurai-625009 Tamilnadu, India *e-mail: tharinichem@gmail.com Received April 1, 2015 Abstract—Silver nanorods were prepared using aqueous extract of Citrus medica fruits under microwave irra- diation for dye degradation. Green synthesized silver nanoparticles were characterized by Ultraviolet-visible spectroscopy and Scanning electron microscopy (SEM). The length of the silver nanorods ranges from 0.5 to 1.5 μm and they exhibit good catalytic activity for the reduction of rhodamine dye. The degradation of rhodamine follows the pseudo first order kinetics. The rate constants were calculated for the different con- centrations of rhodamine. The possible mechanism behind the catalytic performance exhibited by silver nanorods is briefly discussed. Keywords: silver nanorods, rhodamine, catalytic degradation, green synthesis, microwave irradiation DOI: 10.1134/S003602441607030X INTRODUCTION Microwave assisted synthesis of nanomaterials has attracted wider attention in the recent years since it offers simple, safe, time and cost-effective and envi- ronmentally friendly method for the facile synthesis of silver nanoparticles [1]. The silver nanoparticles find applications in wide range of areas such as optics, elec- tronics, engineering, medicine, biology and pharmacy [2, 3]. Generally, most of the organic dyes are toxic and they present a serious hazard to the environment. Rhodamine B (RhB) is the xanthane dye widely used in textile, printing, leather, paint industry, pharma- ceutical and food industry. It is carcinogenic and it is one of the main sources of water pollution. It causes water borne diseases such as nausea, hemorrhage and cancer [4]. Hence the complete removal and degrada- tion of this harmful organic dye becomes essential. In the present study, silver nanorods were synthe- sized by microwave irradiation using Citrus medica (lime fruit) extract as the reducing agent. The catalytic activity of the prepared silver nanorods is investigated in the degradation of rhodamine B dye and their pos- sible catalytic mechanism is also discussed. EXPERIMENTAL Materials. Rhodamine B, sodium borohydride (NaBH 4 ), silver nitrate (AgNO 3 ) were purchased from Sigma-Aldrich and used as received. Preparation of the lime fruit juice. The Citrus medica (lime fruits) were collected from the local market and washed carefully several times with double distilled water. Next lime fruits were cut open and squeezed to extract the juice out. It was then filtered through Whatman filter paper. Microwave synthesis of silver nanorods. In a typical synthesis, 1 mM of AgNO 3 aqueous solution was dis- solved in 10 mL of Citrus medica extract. The reaction mixture was heated in the domestic microwave oven for 60 s at 100 W. The formation of silver nanoparticles was visually identified by the color change in the solu- tion to yellowish orange. Catalytic activity of silver nanorods. In the catalytic experiments, aqueous solution of rhodamine B of var- ious concentrations (5, 10, 50, and 70 μM) and sodium borohydride (0.1 M) were freshly prepared. The prepared silver nanorods solution (2 mL) was mixed with 25 μL of the known concentration of rhodamine, and 25 μL of a 0.1 M NaBH 4 solution was rapidly injected into this mixture. The mixture was then quickly subjected to UV–Vis measurement. RESULTS AND DISCUSSION Characterization of Silver Nanorods The simple strategy used to prepare the silver nanorods is depicted in Scheme 1. The UV–Vis absorption spectrum of the silver nanorods synthe- sized by microwave irradiation is shown in Fig. 1b. Generally the spherical silver nanoparticles show a single and intense surface plasmon resonance peak in 1 The article is published in the original. CHEMICAL KINETICS AND CATALYSIS