Synthesis of some metal/metal sulfide nanoparticles using a superior dissolvable media- Malonic acid (MA) based Deep Eutectic Solvents[DES]

Introduction: A DES may be a liquid upto 100 °C, composed of two or three cheap and safe components (1). However, the widely used method for the preparation of DES is that the heating method (2). Increasing applications of nanoparticles (NPs), such as metal oxide and metal sulfide NPs, lead to heightened environmental concern. The prepared DESs were used as a medium to synthesize cadmium and mercury sulfide nanoparticles via chemical co-precipitation method. Cadmium NPs were synthesised by cadmium (II) chloride with yellow Ammonium sulfide and Mercury NPs by mercury (II) chloride with yellow ammonium sulfide. The synthesised nanoparticles were characterized by UV-Visible, FTIR and scanning electron microscopy (SEM) (3). Cadmium NPs are widely used in toxicology and pharmacology and mercury NPs are used as a catalyst for chemical reactions. Methods: Cadmium NPs were synthesized by mixing cadmium chloride with MA-GLU (Glucose) DES & MA-FRU (Fructose) DES separately in two beakers. Similarly Mercury NPs were synthesized by mixing mercury chloride separately with MA-GLU DES & MA-FRU DES. After mixing, they were stirred using a magnetic stirrer at 1200 RPM for 30 minutes. During the vigorous stirring 0.01 M Yellow Ammonium Sulfide (approximately 8-10ml) was added drop by drop in all beakers. The precipitate of metal sulfide nanoparticles obtained was centrifuged, washed with deionized water followed by methanol and dried. MCl2 + (NH4)2S →MS + 2NH4Cl [M = Cd&Hg] Results & Discussions: The characteristic peaks observed at 250nm is due to the Cadmium NPs obtained in MA-GLU DES and 410 nm due to the Cadmium NPs obtained in MA-FRU DES. Mercury NPs showed significant peaks at 259.40 in case of MA-GLU DES and 258.80 nm in case of MA-FRU DES. FTIR spectrum for Cadmium NPs show peaks at 1163.39 cm-1 corresponds to S-O bond and 702.37 cm-1 is due to S-S bond, at 467.27 cm-1 responds to Cd-S bond. FTIR spectrum for Mercury NPs show peak at 1200- 1000cm-1 corresponds to S-O bond and peaks around 600cm-1 due to the C-S stretching vibration. The morphology of CdS NPs seems to be flower like structure taken upto 200 nm in MA-GLU DES & disc shaped in MA-FRU DES. HgS NPs seems to be sponge like structure in MA-GLU DES & spherical shape structure in MA-FRU DES. Conclusions: Four types of metal/metal sulfide nanoparticles have been successfully synthesized by chemical precipitation method by using highly dissolvable Malonic acid based DES. The UV-Visible and FTIR spectral analysis confirms the absorption maxima and various vibration modes of the metal sulfide nanoparticles. The SEM images clearly show that the synthesized NPs have clear structure with great stability within nanoscales. Keywords: DES, Metal sulfide NPs, FTIR, SEM References: [1] R.Hepzi Pramila Devamani1, R.Kiruthika, P.Mahadevi and S.Sagithapriya, Synthesis and Characterization of Cadmium Sulfide Nanoparticles, International Journal of Innovative Science, Engineering & Technology, 2017;Vol. 4 Issue 1.. [2] Sathyavathi Suresh, Arumugam Manjula,JeyaparakashRajendran, Paramasamy Gunasekaran, Biosynthesis and Characterization of mercury sulphide nanoparticles produced by Bacillus Cereus MRS-1, Indian journal of experimental biology 2013;51 (11): 973-80. [3] Qinghua Zhang, Karine De Oliveira Vigier, Sébastien Royer François Jérôme, Deep eutectic solvents: syntheses, properties and applications, Chem. Soc. Rev., 2012; 41, 7108-7146