Cellulose fiber derived from sugarcane bagasse and polyethylene glycol/acrylic acid/ branched polyethylenimine-based hydrogel composite prepared by gamma irradiation: A platform for mercury (II) ions adsorption
Nattawan Khiewsawai, Thitirat Rattanawongwiboon, Sarute Ummartyotin
Abstract
In this study, cellulose was successfully purified from sugarcane bagasse by alkali treatment and bleaching process. Then, 2-10 wt% of purified cellulose was added into polyethylene glycol and acrylic acid-based hydrogel composite. 25 kGy of gamma irradiation dose was employed to form the gel. With the presence of various cellulose contents, no significant change of functional group was therefore observed. The hydrogel composite was thermally resisted up to 250°C. The microstructure of composite exhibited as an interconnected porosity throughout hydrogel network. Cellulose was located inside hydrogel composite. The gel fraction and porosity for all of composites were reported to be 92-97% and 73-81%, respectively. The swelling behavior was very rapid within initial stage (5 hours) and then, it presented as a plateau region. The presence of purified cellulose significantly offered high dimensional stability. After that, in order to enhance the ability for Hg2+ adsorption, bPEI was coated onto the surface of hydrogel composite. FTIR was employed to evaluate the presence of N-H stretching. At the neutral pH, it defined as an optimal region for adsorption. The efficiency and capacity for Hg2+ adsorption were reported to be 55.17% and 82.94 mg/g in 24 hours, respectively. This was related to the pseudo-second-order kinetic model due to R2 of 0.9941 indicating the chemical adsorption process. Furthermore, EDX analysis confirmed that the existence of Hg was presented onto hydrogel composite surface. It was remarkably noted that purified cellulose from sugarcane bagasse was successfully inserted into hydrogel composite by gamma irradiation technique. It provided a great promise as a platform for mercury ion adsorption.