Diethylenetriaminepentaacetic Acid (DPTA)-modified Magnetic Cellulose Nanocrystals can Efficiently Remove Pb(II) from Aqueous Solution

Surface modification of cellulose nanocrystals (CNC) is essential for improving their reactivity and adsorption capacity. Oxidation, as a conventional modification method of CNC, has strong reaction conditions, which may partially destroy the structure of CNCs. Herein, we propose a mild cellulose modification method, in which diethylenetriaminepentaacetic acid (DPTA) was grafted onto CNC with an aminosilane coupling agent. To facilitate the enrichment and recovery of adsorbents, we prepared magnetic CNC before grafting DPTA, and finally obtained magnetic carboxylic functionalized CNC (MCNC-DPTA). The effects of the reaction parameters on the adsorption process were systematically studied by transmission electron microscopy, X-ray diffraction, Vibration sample magnetometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Additionally, the effects of the solution pH, the initial concentration of Pb, and the adsorption time on the adsorption properties of the materials were evaluated. Furthermore, the structure, morphology, and thermal properties of the solution were systematically studied. After 6 cycle tests, the adsorption amount of Pb(II) by MCNC-DPTA was only reduced by 7%. These results show that MCNC-DPTA is an environment-friendly adsorption material with an excellent Pb(II) removal effect.