FUNCTIONALIZED PAN BASED COPOLYMER RESINS FOR ADSORPTION OF HEAVY METAL IONS

Abstract

In this report functionalized polyacrylonitrile (PAN) based copolymer resins were synthesized which can act as adsorbent for the adsorption of heavy metal/metal ions like Fe2+ and Hg2+ etc. Firstly, PAN and its copolymers were synthesized using styrene, acrylamide and methacrylic acid comonomers. PAN and its copolymers like poly(acrylonitrile-styrene) [PANS], poly(acrylonitrile-acrylamide) [PANAm], and poly(acrylonitrile-methacrylic acid) [PANMA] were functionalized using different concentration of triethylenetetramine (TETA) to obtain two series of polymer resins such as F1-PAN, F1-PANS, F1-PANAm, F1-PANMA, F2-PAN, F2-PANS, F2-PANAm and F2-PANMA, where F1 and F2 represents 1:10 and 1:15 resin to TETA ratio, respectively. These resins have been characterized by using Fourier Transform Infrared Spectroscopy (FTIR) and Energy Dispersive X-Ray Spectroscopy (EDS) techniques. Thermal characterization of resins was performed by Differential Scanning Colorimeter (DSC), Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA). The surface morphology was studied by using Scanning Electron Microscopy (SEM) and viscosity average molecular weight was also determined by viscometric method. The appearance of C=O, C=NH and C=N groups on functionalization of resins was confirmed by FTIR data. EDS study show that F2-PANS and F2-PANMA possess highest adsorption capacity for Hg2+ and Fe2+ metal ions. The TGA technique was used to study the effect of copolymerization and functionalization on copolymers and it was found that there is no adverse effect of copolymerization and functionalization on the thermal stability of the resins. The SEM results also support the EDS results and show the presence of a large number of pores in F2-PANS and F2-PANMA which was probably responsible for their higher adsorption capacity. DMA studies reveal that Glass transition temperature (Tg) of F2-PANMA is highest, i.e., 106.8 °C. The DSC results also support the DMA data. The calculated viscosity average molecular weight for PAN and its copolymers poly(acrylonitrile-styrene), poly(acrylonitrile-acrylamide) and poly(acrylonitrile-methacrylic acid) is found to be 130606, 150304, 157022 and 167233, respectively.