Grafting of vinyl monomer onto gellan gum using microwave: synthesis and characterization of grafted copolymer

In the presence of catalytic amount of ammonium persulfate as initiator, the grafting of polyacrylamide (PAAm) onto gellan gum (GG) was carried out using microwave irradiation. The grafting condition was optimized by varying the microwave power, exposure time, and concentrations of initiator, monomer, and GG. Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy analysis were employed to confirm that PAAm has been grafted onto the GG backbone. The intrinsic viscosity of pure and grafted samples has been measured by using Oswald viscometer. Swelling behavior of graft copolymer has been investigated and pH sensitivity of the graft copolymer was obtained. The flocculation characteristics of grafted and ungrafted polysaccharides have been evaluated in coal (coking and non-coking) suspensions. Graft copolymer shows better flocculation efficacy compared to the base polysaccharides.