For the highly effective removal of hexavalent chromium from aqueous solutions, a new polyethylenimine (PEI) grafted porous adsorbent, a cellulose@PEI aerogel (CPA-2) composite, was synthesized through a glutaraldehyde crosslinking reaction between the amine groups of PEI and the hydroxyl groups of cellulose. The physicochemical properties of this new adsorbent were characterized by FT-IR, SEM, EDX, XPS, etc., and the modification of grafting with PEI was demonstrated by FT-IR, EDX and XPS analyses. The effects of pH, contact time, initial concentration and PEI content on Cr(VI) sorption were systematically investigated. Experimental data were well described by the Freundlich isotherm and the pseudo-second-order model in a batch system, demonstrating that chemisorption was the rate-controlling factor for Cr(VI) removal with CPA-2. Furthermore, the experimental maximum adsorption capacity of CPA-2 was 229.1 mg g⁻¹, which was around 12 times higher than that of cellulose aerogel (CA) (18.7 mg g⁻¹). The Thomas model was well fitted to the breakthrough curves of adsorption processes under different fixed-bed conditions. Above all, the exhausted bead-like adsorbent could be easily separated and regenerated without significant loss of adsorption capacity. Accordingly, this new composite material should be a promising sorbent for sewage disposal, with advantages of high performance, low-cost, biodegradability and excellent reusability.

The design of advanced supercapacitors requires electrode materials that combine high surface area with a developed hierarchical porous structure to facilitate ion transport and electrolyte permeability. Herein, we report a cross-linking and in situ sulfuration strategy for synthesizing nickel sulfide (Ni₃S₂) nanocrystal-attached cobalt sulfide (Co₉S₈) encapsulated on three-dimensional (3D) N-doped hierarchical porous carbon (Ni₃S₂@Co₉S₈/N-HPC). The Ni₃S₂@Co₉S₈/N-HPC composite was extensively studied using different characterization technologies. The results revealed that the obtained material integrated the advantages of a developed N-doped carbon framework (fast ion transport and excellent electrical conductivity) and transition metal sulfide species (high theoretical specific capacitance). Benefiting from the synergistic effect of a strawberry-like Ni₃S₂@Co₉S₈ structure and 3D interconnected hierarchical porous carbon, the resulting Ni₃S₂@Co₉S₈/N-HPC composite exhibited an ultrahigh attractive specific capacitance of 1970.5 F g⁻¹ at a current density of 0.5 A g⁻¹ and excellent cycling stability with a capacitance retention of 89.5% after 5000 cycles at 10 A g⁻¹. In addition, an asymmetric supercapacitor (ASC) of Ni₃S₂@Co₉S₈/N-HPC//HPC was assembled in a 6 M KOH electrolyte. It delivered an energy density of 77.1 W h kg⁻¹ at a power density of 263.3 W kg⁻¹, and it remained as high as 36.1 W h kg⁻¹ even at 25.9 kW kg⁻¹. It is believed that the presented work opens up a new strategy to fabricate high-performance supercapacitor electrodes.

An investigation of design principles, preparation processes and structural properties is carried out to predict the development tendency of marine polysaccharide-based electromagnetic response materials which cater to the current targeted demands.