Preparation of poly vinyl alcohol/lignin hydrogels and investigation of the adsorption for methylene blue
Abstract
In this study, hydrogels from polyvinyl alcohol and lignin were synthesized. Glyoxal was used as crosslinking agent with the role of forming bonds between polyvinyl alcohol and lignin molecules. The adsorption capacity of the hydrogels for methylene blue (MB) was investigated with the various initial concentrations of methylene blue (MB) solution. The study of adsorption isotherm was conducted at 31 o C and pH 7 with Langmuir and Freundlich models. The correlation coefficients (R 2 ) of the graphs showed that the experimental data fitted Langmuir model. This proved that MB adsorbed on the hydrogel by mono-layer adsorption mechanism. MB adsorption effiency was over 88%. In addition, the properties of PVA/lignin hydrogels were studied by several analytical methods, including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction method (XRD) and UV–visible spectrophotometry (UV-Vis).