Microfibrillated cellulose reinforced poly(vinyl imidazole) cryogels for continuous removal of heavy metals

Abstract

Interconnected macro‐porous cryogels with robust mechanical structure and high adsorption capacity are desirable for the wastewater clean‐up. However, some functional alkenyl‐based monomer such as vinyl imidazole (VIM) could not be individually polymerized to form the cryogel with a robust structure for applications. Herein, a strategy has been developed to fabricate the poly(VIM) cryogel using microfibrillated cellulose (MFC) as reinforcing agent. Structural characterizations indicated that the poly(VIM)/MFC showed interconnected macropores of 12 ± 10 μm and high VIM contents. Underwater compression experiments displayed that the hysteresis loops changed slightly and the energy loss coefficients were less than 23% during loading‐unloading 200 cycles, highlighting the excellent shape recovery and fatigue resistance. Batch adsorption indicated that the adsorption capacities of the poly(VIM)/MFC cryogel to Cu(II), Pb(II), Zn(II), Cd(II), Ni(II), and Co(II) were 87.4, 53.9, 48.6, 44.3, 23.8, and 20.1 mg/g, respectively. The pseudo second‐order kinetic and Langmuir model can fit the adsorption process well, confirming the single‐layer homogeneous chemisorption. Dynamic adsorption displayed that the loaded Cu(II) ions could be rapidly adsorbed and hardly flow through the poly(VIM)/MFC cryogel, indicating the extremely fast adsorption at the flow mode. This study shows a novel strategy to fabricate the robust cryogel for environmental remediation.

Freezing-triggered gelation of quaternized chitosan reinforced with microfibrillated cellulose for highly efficient removal of bilirubin

“…Herein, we chose MFC as the nanofiber reinforcement to demonstrate this technique because of its good biocompatibility, high aspect ratio for entanglement, and applications in our previous works. [47][48][49] Each BVSM molecule possesses two vinyl groups that may undergo an addition reaction with nucleophiles (amino and hydroxyl groups). Chemical crosslinking experiments at room temperature were conducted for the QCS/MFC mixture containing BVSM, demonstrating no gelation within 24 h. However, robust and shape-recovered QCS/MFC cryogels were produced at À12 1C for 12 h, indicating that BVSM was triggered by the freezing process to chemically crosslink QCS and MFC.…”