Obtaining and Application of New Cellulose- and Graphene Oxide-Based Adsorbents for Treatment of Industrial Waste Containing Heavy Metals

The paper presents the results of studies on the preparation and properties of composite granules produced by phase inversion from cellulose (CEL) solutions in 1-ethyl-3-methylimidazole acetate (EMIMAc), containing nano-addition in the form of graphene oxide (GO) in N,N-dimethylformamide (DMF). Water absorption and sorption of such compounds as FeCl₃, methylene blue (MB) and bovine serum albumin (BSA) were studied. In addition, attempts were made to investigate the sorption properties of the obtained cellulose granules in terms of metals removal from galvanizing wastewater. Among the many components, iron and lead were found to have the highest concentration (~ 1 mg Fe/dm³; ~2 mg Pb/dm³) in the tested wastewater sample. The qualitative and quantitative composition of the wastewater was examined by UV-Vis spectrophotometry. The studies show that doping of cellulose with Graphene oxide clearly affects the physical properties of this biopolymer. GO improves the water absorption of CEL/GO composite cellulose granules only in the concentration above 0.05% w/w. For a concentration of 0.1% w/w of GO in cellulose, water absorption is increased by ~108% compared to pure cellulose granules. In addition, the use of dry and wet granules in the study changes their sorption properties with respect to all tested substances. Studies on test solutions have shown that the sorption of cellulose granules decreases with increasing molar mass of test compounds, in the following order: FeCl₃, methylene blue (MB) and bovine albumin (BSA). This means that the cellulose granules obtained in the experiment are made up of small micropores, which makes the diffusion of compounds of high molecular weight difficult. The best sorption results were obtained for ferric ions and amounted to 66–72% for FeCl₃ solution, and ~92% for the wastewater that was sorbed on pure cellulose granules.