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The study on low-cost drying–redispersion process for the storage and transport of nanocellulose has been a great challenge in practical applications. The existence of abundant hydroxyl groups on the nanocellulose surface causes a strong tendency of agglomeration of the nanoparticles in the dry state. In this paper, we propose a new method to solve this problem by controlling the solid content of cellulose suspension to obtain a well-dispersed nanocellulose with reduced fibrillar alignment in the following freeze-drying treatment. The results show that when the solid content in the original suspension varied between 4 and 10 wt %, the morphology of the aerogel transformed from the membranous to fibrillar network with increasing specific surface area and redispersibility, and further dehydration was detrimental. This phenomenon is mainly attributed to the entanglement of cellulose fibrils in the cellulose network, which suppressed the growth of ice crystal during the dry-freezing process. In addition, the interaction between intra-/intermolecular hydrogen bonds is also proved to be responsible for the variation of the cellulose morphologies and the thermal decomposition temperature. This research will provide an effective and convenient way for the transportation and storage of nanocellulose, aiming at its large-scale industrial applications.

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A novel adsorbent for divalent metal cations was prepared as nanocomposite of Fe–Mg (hydr)­oxide with graphene oxide by one-step coprecipitation. This material showed adsorption selectivity of Pb2+ > Cu2+ > Ag+ > Zn2+ ≫ Co2+, Ni2+, Cd2+ with high adsorption capacity of 100–600 mg/g for Pb2+, Cu2+, Ag+, and Zn2+. Distribution coefficient (K d) was as high as ∼107 mL/g for Pb2+ and Cu2+. The adsorption isotherms for Pb2+, Cu2+, Ag+, and Zn2+ followed the Langmuir model, indicating monolayer adsorption. The adsorption kinetics for Pb2+, Cu2+, Ag+, and Zn2+ followed pseudo-second-order model, suggesting chemisorption. Removal of 50 ppm Pb2+ or Cu2+ from 100 mL solution by 0.1 g of the nanocomposite was over 99.7%. The thermodynamics studies implied that the adsorption process toward heavy metals was spontaneous and endothermic. Together with recyclability through magnetic separation, this adsorbent would be useful in polluted water processing.