Chemical modification of microcrystalline cellulose with polyethyleneimine and hydrazine: Characterization and evaluation of its adsorption power toward anionic dyes.

Functionalization and various applications of biomaterials have progressively gained a major interest due to the cost-effectiveness, renewability, and biodegradability of these substrates. The current work focalized on the functionalization of microcrystalline cellulose with polyethyleneimine solution (3 %, 5 %, and 10 %) and hydrazine sulfate salt (1:1, 1:2, 2:1) using an impregnation method. Untreated and treated samples were characterized using FT-IR, SEM, XRD, TGA, and DTA analyses. The crystallinity index values for control microcrystalline cellulose, cellulose-polyethyleneimine, and cellulose-hydrazine were 57.13.8 %, 57.29 %, and 52.62 %, respectively. Cellulose-polyethyleneimine (5 %) and cellulose-hydrazine (1:1) displayed the highest adsorption capacities for calmagite (an anionic dye). At equilibrium, the maximum adsorption capacities for calmagite achieved 104 mg/g for cellulose-polyethyleneimine (5 %), 45 mg/g for cellulose-hydrazine (1:1), and only 12.4 mg/g for untreated cellulose. Adsorption kinetics complied well with the pseudo-second-order kinetic model. The adsorption isotherm fitted well with the Langmuir isotherm. Overall, the functionalized cellulosic samples could be considered potential materials for the treatment of contaminated waters.

Populus tremula, Nerium oleander and Pergularia tomentosa seed fibers as sources of cellulose and lignin for the bio-sorption of methylene blue.

Cellulose-based substrates could represent potential funds for the sorption of pollutants. Herein, methylene blue was selected for demonstrating the bio-sorption efficiency of Nerium oleander, Pergularia tomentosa and Populus tremula seed fibers. Their cellulose contents were 45%, 43.8% and 60%. Their lignin amounts were 21%, 8.6% and 12%, respectively. Fourier Transform InfraRed suggested that the interaction of these bio-products with methylene blue could occur between hydroxyl and ester groups of cellulose and lignin and the sulfur and nitrogen atoms of the dye. Scanning Electron Microscopy showed a swelling of the bio-matters after dye biosorption. From X-Ray Diffraction, the shifting for higher values of the peaks related to the amorphous phase indicated the establishment of new rearranged regions. Such change from the decomposition behavior event studied by Thermogravimetric Analysis/Differential Thermal Analysis revealed that methylene blue was interacted with cellulose and lignin structures. The effect of adsorbent dosage, pH, time, dye concentration and temperature was investigated in controlled batch experiments. Excellent sorption capacities followed the order: Nerium oleander (280.2 mg g-1) > Populus tremula (168 mg g-1) > Pergularia tomentosa (145.3 mg g-1). Freundlich fitted best the equilibrium data suggesting cooperative interactions via physisorption and chemisorption phenomenon. Kinetic data complied well with the pseudo-second-order suggesting a chemisorption mechanism.