No abstract

The development of sustainable and efficient absorbents for oil and organic pollutants cleaning is an attractive and challenging work. Here, novel superhydrophobic microfibrillated cellulose aerogels (HMFCAs) with high lipophilicity, ultralow density (≤5.08 mg/cm3), superior porosity (≥99.68%) as well as extremely high mechanical stability were successfully prepared from microfibrillated cellulose aerogels (MFCAs) via a facile and environmentally friendly silanization reaction in liquid phase. The superhydrophobicity of the as-prepared HMFCAs (water contact angle as high as 151.8°) was attributed to the formation of polysiloxane on the surface of HMFCAs by the silanization reaction. The HMFCAs exhibited excellent oil/water selective absorption capacity with oil absorption up to 159 g/g. The reusability experiment showed that the adsorption capacity still exceeded 92 g/g for pump oil after 30 absorption cycles, demonstrating its superior reusability. Our work paves the way for the development of sustainable and efficient absorbents toward oils and organic pollutant removal applications.

Sustainable microfibrillated cellulose (MFC) aerogels are considered to be good templates for the growth of functional organic or inorganic nanoparticles. In this work, MFC aerogels with high porosity (99.9%) and low density (2.91 mg/cm 3 ) were produced by freeze-drying. Then the obtained MFC aerogels were used as templates for the synthesis of MFC/polypyrrole (PPy)/silver nanoparticles (Ag) hybrid aerogels by a simple dip-coating method. Our results demonstrated that the obtained hybrid aerogels maintained the attractive features of the pristine MFC aerogels, such as high porosity, low density, and high compressive stress, during the preparation process. Compared with MFC aerogels and MFC/ PPy hybrid aerogels, the MFC/PPy/Ag hybrid aerogels exhibited enhanced antimicrobial and electrical conductive properties due to the combination of PPy and Ag. Moreover, the electrical conductivity and compressible properties of the MFC/PPy/Ag hybrid aerogels led to their pressure responsive property. These features make the hybrid aerogels promising candidates for wound healing, energy storage, and pressure sensing applications.

Here, we reported a facile strategy to create superhydrophobic aerogels via freeze-drying of silylated cellulose nanofibers and silica nanoparticles mixed suspensions. The as-prepared aerogels possessed a hierarchical porous structure with high roughness and low surface energy. The hierarchical rough structure and low surface energy endowed the resultant aerogels with superhydrophobicity (water contact angle up to 168.4°). Importantly, the composite aerogels could separate surfactant-stabilized water-in-oil emulsions without external pressure, with high separation efficiency (>99%) and high flux (1910 ± 60 L m–2 h–1). The aerogels were easily recyclable and showed great antifouling performance, which could meet the requirements for long-term use. We also assembled a simple device to collect oil directly from water-in-oil emulsions with the obtained aerogel and a self-priming pump. The fabrication of the composite aerogels in our work provides a versatile way to fabricate cellulose composite materials for water-in-oil emulsions separation.

By taking advantage of cellulose, graphene oxide (GO), and the process for crosslinking using epichlorohydrin (ECH), we propose a simple and novel method to prepare GO/cellulose hydrogel with good potential to adsorb metal ions. GO nanosheets containing carboxyl and hydroxyl groups were introduced into the surface of the cellulose hydrogel with retention of the gel structure and its nanoporous property. Due to the introduction of GO, the GO/cellulose composite hydrogels exhibited good compressive strength. Adsorption capacity of Cu2+ significantly increases with an increase in the GO/cellulose ratio and GO/cellulose hydrogel showed high adsorption rates. The calculated adsorption capacities at equilibrium (qnormalecal) for GO/cellulose hydrogel (GO:cellulose = 20:100 in weight) was up to 94.34 mg·g−1, which was much higher than that of the pristine cellulose hydrogels. Furthermore, GO/cellulose hydrogel exhibited high efficient regeneration and metal ion recovery, and high adsorption capacity for Zn2+, Fe3+, and Pb2+.