Hypothesis The effective separation and recovery of oils from water is important for the protections of ecosystems and the environment. Polymeric porous monoliths have been demonstrated as attractive absorbents for oil/water separation. However, the recyclability was mainly realized by squeezing, combustion, or centrifugation, which may restrict in elastic materials, destroy the adsorbates or need special apparatus. Thus it is desirable to developing monoliths with controllable oil absorption and desorption. Experiments A series of “smart” monoliths with pH-induced switchable wettability were fabricated by high internal phase emulsion (HIPE) polymerization and epoxide ring-opening for the incorporation of amine groups. The resultant monoliths and their wettabilities were examined using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), nitrogen adsorption/desorption and contact angle analysis, respectively. The oil separation efficiency and recyclability were evaluated. Findings The monoliths with macroporous structure can undergo switchable wettability under reversible pH stimulation. As an absorbent, the monoliths not only separated and recovered organic solvents and oils (including crude oil) from aqueous mixtures through a reversible and recyclable absorption and desorption process upon alternating the pH between 7.0 and 1.0, but also continuously expulsed oils from water surfaces in a continuous manner with the aid of external driving pressures. Moreover, the monoliths also allowed the effective separation of surfactant-free and surfactant-stabilized oil-in-water emulsions with high separation efficiency.
Yang Yan,Linlin Zang,Tianwei Dou,Haicheng Li,Liguo Sun,Yanhong Zhang
In this work, we prepared a hollow Co 3 O 4 nanoparticles (NPs) immobilized reduced graphene oxide (rGO)/carbon monolith (HCGCM) via a one-step carbonization method. The doping of nanomaterial and transition metal oxide can improve the poor conductivity and low capacitance of pure carbonaceous materials. The optimal addition concentration of polystyrene microspheres as a template provided the HCGCM composite with a hierarchical pore structure and a large specific surface area (1600 cm 2 /g), which is conducive to generating sufficient electroactive sites. At the same time, three dimensional (3D) interconnected pores shorten ion transport paths and reduced diffusion resistance of ions. Due to the existence of pseudocapacitive behavior, the HCGCM composite, as an electrode material working in a three-electrode system, achieved a high capacitance value of 1106 F/g at a current density of 1 A/g. In two-electrode system, the asymmetric supercapacitor had excellent stability performance and remained about 86.7% capacitance after 5000 cycles test. Moreover, it also exhibited a maximum energy density of 66.7 Wh/kg at power density of 750 W/kg. Thus, the strategy of manufacturing 3D porous electrodes is beneficial to improve the overall electrochemical performance of supercapacitors .
Gaseous Hg 0 is one of the most deadly and hard-to-dispose pollutants. The oxidation of Hg 0 is a promising route, but the rational design and synthesis of highly efficient catalysts still remain grand challenges. Herein, CuO@Cu 2 O (or Cu x O) heterostructured nanoparticles uniformly monodispersing on porous carbon monolith were designed and successfully synthesized using oligo( m -phenylenediamine)-Cu 2+ complex as raw material. The Cu x O-carbon catalyst contains ∼28 wt% of Cu. Based on density functional theory calculation, the CuO@Cu 2 O junction interfaces can accelerate the Hg 0 oxidation by significantly reducing the energy barriers of reaction. Only 1 mg of the catalyst can catalyze the oxidation of more than 90 % of Hg 0 with [HCl] = 0.5 ppm, [O 2 ] = 6 vol%, T = 150 °C. The poisoning effect of either SO 2 or H 2 O on the catalysts is weak. Moreover, a long-term test confirmed that the Hg 0 oxidation rate can maintain more than 90 % even in the co-presence of SO 2 (5000 ppm) and H 2 O (10 vol%).
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