Chuanjie Fan

In this paper, a graphene‐oxide/carboxymethyl‐chitosan/polyvinyl‐alcohol (GO/CMC/PVA) composite nanofiber membrane was prepared by electrospinning and cross‐linking with glutaraldehyde (GA) to improve the water resistance. The composite nanofiber membrane can be used in the field of heavy metal adsorption. The membrane was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X‐ray diffraction. The effects of GO concentration, adsorption time, and initial concentration of heavy‐metal ion (Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺) solution on the adsorption performance of the fiber membranes were investigated. The results showed that the addition of GO can reduce the diameter of nanofibers. GO, CMC, and PVA exhibited good compatibility, and the intermolecular hydrogen bonding improved. The addition of GO also improved the crystalline properties of the composite fiber membrane. In the optimal cross‐linking condition, GA was saturated by steam cross‐linking for 6 h. The introduction of GO improved the adsorption capacity of the membrane for heavy metals in water. The utmost adsorption capacities for Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺ were 262.1, 237.9, 319.3, and 413.6 mg/g when using the cross‐linked composite fiber membranes, respectively. The results of adsorption kinetics and thermodynamics showed that the adsorption process accorded with the pseudo‐second‐order kinetic model and Langmuir–Freundlich isotherm model.

A new type of polydopamine functionalized graphene oxide/carboxymethyl chitosan (DGO/CMC) composite aerogels was synthesized via sol–gel once‐forming self‐assembly and lyophilization. Polydopamine (PDA) on the surface of GO nanosheets replaced those traditional crosslinking agents to connect CMC chains via hydrogen bonding for the establishment of 3D porous aerogels. With the increasing proportion of CMC, the microstructure of aerogels changed from small pores to large plate‐bridge‐like pores. In addition, their maximum compressive strengths were 6.767, 11.94, and 16.98 MPa under 90% compressions, respectively, which increased in accordance with CMC content. Furthermore, the adsorption system of the aerogels was simulated well by the pseudo second‐order kinetic model and the Langmuir isotherm model, with maximum mass adsorption capacities of 170.3, 186.8, and 312.8 mg/g for Cu²⁺, Ni²⁺, and Pb²⁺ ions, respectively. These composite materials have potential applications for water purification because of their simple and efficient synthesis and excellent recyclability and reusability.