Modification of gum ghatti via grafting with acrylamide and analysis of its flocculation, adsorption, and biodegradation properties

Abstract

In this work, an environmentally friendly gum ghatti-crosslinked-polyacrylamide (Gg-cl-PAAM) hydrogel was synthesized from gum ghatti (Gg) and acrylamide (AAM) using a microwave-assisted grafting technique, and tested for use in water purification applications as an adsorbent and flocculent. The Gg-cl-PAAM was characterized using SEM, FTIR, and TGA, and displayed pH responsive swelling behavior, with maximum swelling (2117%) observed in solution with neutral pH. The flocculation characteristics of Gg-cl-PAAM were tested in clay solutions as a function of pH, temperature, and the polymer mass loading, showing that the best performance is obtained at neutral pH at 40°C. The adsorption capacities of Gg-cl-PAAM for the removal different dyes such as brilliant green (BG), rhodamine B (RhB), congo red (CR), and methyl orange (MO) were tested, revealing that the adsorption of all dyes followed the Langmuir isotherm model, with q_m values of 523.62mgg^-1 for BG, 421.60mgg^-1 for RhB, 179.09mgg^-1 for CR, and 173.69mgg^-1 for MO. Finally, the environmentally friendly nature of Gg-cl-PAAM was examined using the soil-burial composting method, which demonstrated 93% degradation of the Gg-cl-PAAM hydrogel within 60days.

Keywords: Adsorption; Biodegradable hydrogel; Dye removal; Flocculation.