Preparation of Magnetic CuFe2O4@Ag@ZIF-8 Nanocomposites with Highly Catalytic Activity Based on Cellulose Nanocrystals.

A facile approach was successfully developed for synthesis of cellulose nanocrystals (CNC)-supported magnetic CuFe2O4@Ag@ZIF-8 nanospheres which consist of a paramagnetic CuFe2O4@Ag core and porous ZIF-8 shell. The CuFe2O4 nanoparticles (NPs) were first prepared in the presence of CNC and dispersant. Ag NPs were then deposited on the CuFe2O4/CNC composites via an in situ reduction directed by dopamine polymerization (PDA). The CuFe2O4/CNC@Ag@ZIF-8 nanocomposite was characterized by TEM, FTIR, XRD, N2 adsorption-desorption isotherms, VSM, and XPS. Catalytic studies showed that the CuFe2O4/CNC@Ag@ZIF-8 catalyst had much higher catalytic activity than CuFe2O4@Ag catalyst with the rate constant of 0.64 min-1. Because of the integration of ZIF-8 with CuFe2O4/CNC@Ag that combines the advantaged of each component, the nanocomposites were demonstrated to have an enhanced catalytic activity in heterogeneous catalysis. Therefore, these results demonstrate a new method for the fabrication of CNC-supported magnetic core-shell catalysts, which display great potential for application in biocatalysis and environmental chemistry.

A polyethylenimine/salicylaldehyde modified cellulose Schiff base for selective and sensitive Fe3+ detection.

We describe a new solid-state colorimetric sensor synthesized by micro-crystalline cellulose (MCC) in the presence of polyethylenimine (PEI) and salicylaldehyde (SA) via an oxidation process and two successive Schiff base reactions. The formation of the Fe3+ complex led to color change detectable by eye, as well as an absorption peak at 501 nm causing fluorescence quenching. The signal was linear with the concentration ranging from 4 to 20 ppm; the detection limit is 0.01 ppm, making this a sensitivity and reliable monitoring platform for Fe3+ detection. Orbital electron distribution and computational studies were also carried out using density functional theory (DFT) to better supplement the sensor's detection performance. Finally, the sensing mechanism is discussed in detail.