Rapid removal of anionic dyes from water, using poly (diallyldimethylammonium chloride) and branched polyethyleneimine functionalized cellulose extracted from Echinops bannaticus leaves

Abstract

In the current work, we report the extraction and chemical functionalization of cellulose from Echinops bannaticus (E. bannaticus) leaves. Poly (diallyldimethylammonium chloride) (PDDAC) and branched polyethyleneimine (BPEI) were used as amine reagents. The prepared cellulosic substrates were characterized using several analytical techniques including SEM, FT-IR, XRD, and TGA/DTG techniques. FT-IR data proved the chemical interaction between hydroxyl groups of cellulose and amine groups of PDDAC and BPEI. XRD pattern of the extracted cellulose showed main peaks situated at 14.4°, 22.7° and 34.3°, corresponding to (110), (200) and (040) lattice planes of crystalline cellulose. The functionalization of cellulose with PDDAC and BPEI did not affect the crystallinity. After chemical modification, the cellulosic fibers appeared physically deformed with the existence of some surface alteration. The variation in thermal decomposition values indicated that many non-cellulosic components were removed during alkalization and bleaching processes. After thermal degradation, the residual mass was found to be more important in the case of raw E. bannaticus fiber (16.59 %) compared to the extracted cellulose (5.31 %). The analyzed cellulosic materials were investigated for their ability to adsorb an anionic Acid Blue 25 (AB25) dye from water. The adsorption results showed high adsorption capacities of the aminated cellulosic materials. Under optimum conditions (mass adsorbent = 0.01 g, pH = 5, time = 60 min., and T = 22 °C), the adsorption capacities of the extracted cellulose-HPEI (3 %), extracted cellulose-PDDAC (5 %), and unmodified extracted cellulose were 109 mg/g, 64 mg/g, and 24 mg/g, respectively. The fitting of the adsorption data with theoretical kinetic and isotherm equations indicated that the mechanism complied well with pseudo-second-order and both Langmuir and Freundlich models. Overall, we reported an efficient adsorbent derived from naturally abundant and cost-effectives bio-resources for eliminating hazardous anionic dyes from polluted waters.