Novel nanoporous magnetic cellulose−chitosan composite microspheres (NMCMs) were prepared by sol−gel transition method using ionic liquids as solvent for the sorption of Cu(II). The composite microspheres were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Subsequelty, the adsorption of Cu(II) to NMCMs was investigated systematically with varried parameters such as pH, contact time, and initial concentration. Results revealed that the composite microspheres exhibited efficient adsorption capacity of Cu(II) from aqueous solution, due to their favorable chelating groups in structure. The adsorption process was best described by a pseudo-second-order kinetic model, while isotherm modeling revealed that the Langmuir equation better describe the adsorption of Cu(II) on NMCMs as compared to Freundlich model. Moreover, the loaded NMCMs can be easily regenerated with HCl and reused repeatedly for Cu(II) adsorption up to five cycles. The environmental friendly microspheres were expected to be a promising candidate for future practical use in heavy metal ions removal.

Highlights▪ A simple in-situ oxidation approach was developed to prepare MnO2/NCNT. ▪ Prepared samples showed boosted activity for HCHO degradation at low temperature.▪ MnO2/NCNT exhibited better activity and selectivity than MnO2/CNT. ▪ Mechanism of improved HCHO oxidation by MnO2/NCNT was revealed.

Solar vapor generation is a renewable and hopeful technology for obtaining freshwater from underground water, dyeing wastewater, and seawater. Herein, hierarchical MnO2 nanosheets grown on cotton fabric (Mn-CF) have been developed for solar-driven water evaporation. Black MnO2 nanosheets and nanoflowers are in situ chemically deposited on cotton fabric (CF), which leads to a solar absorption ability as high as 95% from 300 to 2500 nm. Due to the synergistic effect of the super-hydrophilic CF and hierarchical MnO2 nanosheets, Mn-CF results in a water evaporation rate of 1.40 kg m–2 h–1 with the photothermal conversion efficiency of 87.48% under 1 sun illumination (1 kW m–2). During the desalination test, Mn-CF can be renewed by washing off the steamed salts through a simple ultrasonication or hand-washing. Moreover, Mn-CF remains stable after 40 cycles, each lasting 1 h under 1 sun irradiation. A Mn-CF-based solar steam generator (Mn-CF-SSG) enables to effectively purifying simulated dyeing wastewater and seawater using natural sunlight. The cost of preparing 1 m2 Mn-CF is about $1.5. This work provides a simple method to prepare flexible and washable Mn-CF-SSG with low-cost and high efficiency that has huge potential for practical application of seawater desalination.

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