查看更多>>摘要：Titanium dioxide nanotube (TNT) amalgamated graphene oxide (GO) matrix was blended with cellulose triacetate (CTA) polymer to form a new kind of mixed matrix membranes (MMMs) for the selective biogas upgrading. The effect of hybrid fillers on the physico-chemical, diermal and mechanical properties of membranes were studied using different spectroscopic techniques. Notable improvements on these properties were observed on MMMs as compared to the pristine membrane. Similarly, resulting MMMs exhibited higher CO2 adsorption affinity. Furthermore, single gas permeation measurements revealed higher permeability as well as selectivity for TNT@GO/CTA membrane. CO2 permeability increased almost 7 times, reaching 22.54 Barrer, whereas CO2/CH4 selectivity increased nearly three folds from 25.06 for the pristine membrane to 86.69 for TNT@GO/CTA membrane and reached the Robeson 2008 upper bound. The long term stability experiment of the TNT@GO/CTA membrane confirm the anti-aging ability suggesting its practical application in the bio/natural gas upgrading process. These results established an effective modification approach for applying alternative porous hybrid fillers into gas separation applications.
查看更多>>摘要：To achieve highly efficient separation of oil/water mixtures, superhydrophobic/oleophilic, membranes based on covalent silanization of silica nanoparticles on metallic meshes were obtained. The membranes were prepared in a scalable two-step process. The characterization of modified nanoparticles as well as the membranes includes XPS, ATR, solid state NMR, SEM, EDS, TGA and tensile strength essays. In addition, several experiments were conducted in order to characterize the superhydrophobic behavior (water contact angle (WCA) measurements, oil flux, maximum water pressure on the membrane, affinity of the particles by organic phase, etc.). Although the silica nanoparticles are highly hydrophilic, after the modification they become strongly hydrophobic providing chemical resistance to hard water. The system allowed the separation of oil-water mixtures, being washable and reusable.
查看更多>>摘要：The separation of binary azeotropes with low cost and energy consumption is important and challenging for the production of chemicals. A hybrid heat-integrated pressure-swing distillation process (HHIPSD) with heat pump was proposed for the separation of both maximum- and minimum-boiling azeotropes in this work. Compared to the conventional fully heat-integrated pressure-swing distillation process (FHIPSD), the HHIPSD process showed lower total annual cost and higher thermodynamic efficiency in the separation of seven minimum-boiling azeotropes of benzene-ethanol, methanol-acetone, methanol-ethyl acetate (EA), ethanol-EA, acetonitrile-ethanol, isobutanol (IBA)/isobutyl acetate (IBAc) and diisopropyl ether (DIPE)-isopropyl alcohol (IPA), and two maximum-boiling azeotropes of water-ethylenediamine (EDA) and acetone-chloroform. For the best performance of HHIPSD process, robustness and algorithm optimization were studied in this paper. Scenario analysis method was proven to greatly enhance the convergence of HHIPSD models. The improved genetic algorithm (GA) was modified by particle-swarm optimization and pattern search method and validated by 13 benchmark functions. Meanwhile, different constraint handling methods were studied to ensure the better performance of the improve GA method. With the improvement of model robustness and optimization algorithm, the HHIPSD process achieved 21.6 % and 4.2 % decrease of TAC for water-EDA and methanol-acetone separation, respectively, compared to FHIPSD process. The proposed HHIPSD process together with the optimization strategy suggests the pressure-swing distillation technology can be highly effective in azeotrope separation.
查看更多>>摘要：Interfacial polymerized polyamide composite nanofiltration membrane has been widely used in wastewater treatment. Despite its high selectivity towards water and solutes, differentiation of solutes with similar size is still a great challenge. Herein, we propose that polyamide nanofiltration membrane with uniform and tunable pores and sub-nm precision selectivity can be achieved through electrospraying strategy via controlling relative humidity (ratio of practical vapor pressure P1 and its saturated vapor pressure P_s). The enhanced relative humidity facilitated the dispersion of piperazine (PIP) monomers on substrate and the reaction with trimesoyl chloride (TMC). The membrane (M78) fabricated at high humidity (70%-80%) exhibited more uniform pore size and narrower size region (0.26 nm-0.49 nm) at a designed rejection difference (e.g., 50%) compared with the membrane (0.26 nm-1.0 nm) obtained at low humidity (30%-40%). Membrane selectivity (e.g., Na2SO4 and NaCl) was an order of magnitude high when humidity increased from 30%-40% to 70%-80%. The current study offered a facile and effective strategy for fabricating polyamide nanofiltration membrane with uniform pores and sub-nm selectivity.
查看更多>>摘要：Efficient CO2 capture and separation, such as from natural gas, biogas, and landfill gas, is highly desirable to maximize the use of energy and alleviate carbon emission and greenhouse effect. A novel approach of charge/ strain-regulated gas capture and separation has been proposed to offer the advantages of reversibility and controllable kinetics. We demonstrated the highly controllable CO2 capture and separation from CO2/CH4 on porous g-C9N7 nanosheets with varying charge densities and strains using molecular dynamics (MD) simulations and first-principle density function theory (DFT) calculations. The remarkable CO2 permeance up to 5.94 × 10~7 GPU can be achieved by charge engineering, such as through the strategies of electrochemical methods. A tunable CO2 separation performance was exhibited under the condition of tensile strain. The permeance of CO2 was found to increase with increasing the applied tensile strain, and the maximum permeance was 3.61 x 107 GPU with 7.5% strained g-CgN7 membrane. More interestingly, a promising approach for combining a charged state with the strain engineering was explored to investigate the synergistic effect. Under conditions of 1 e' negative charge and 3% tensile strain on g-CgN7 membrane, the CO2 permeance reached 3.18 x 107 GPU, which was 9 times higher than only with adding 1 e'', and 8 times higher than only applying 3% strain. Additionally, the temperature effect indicated that the g-C9N7 membrane can be served as an excellent candidate for CO2/CH4 separation at ambient conditions. These results provide useful guidance for developing advanced materials with highly controllable CO2 capture and separation properties.
查看更多>>摘要：Peroxydisulfate (PDS) activation by a novel magnetically recoverable reduced graphene oxide (rGO)/MnFe2O4 composite was studied for the removal of tetracycline (TC), a widely used antibiotic. The catalytic performance of rGO/MnFe2O4 was greatly higher than that of bare MnFe2O4, and the degradation rate of TC tended to be raised as the content of rGO in composite catalyst increased. After reaction for 80 min, the optimized rGO/ MnFe2O4-15 catalyst can degrade 90.1% of TC in water (20 mg/L) with the addition of 1.5 g-L~(-1) PDS. The effect of PDS dose, temperature, initial pH, inorganic anions and humic acid on TC removal was also examined. The quenching experiments and electron paramagnetic resonance (EPR) tests suggested that the radical (SO4~(·-) and] ?OH) and non-radical (~1O2) oxidation processes worked together for the degradation of TC in rGO/MnFe2O4-PDS system. PDS was activated to produce SO_4~(·-) by MnFe2O4, and rGO can donate electron to facilitate the redox cycle of ≡M(lI)/≡M(III) (M refers to Mn or Fe), thus promoting the formation of SO4~(·-). The carbonyl group in rGO participated in the activation of PDS to generate ~1O2. The linear sweep voltammetry indicated that rGO/ MnFe2O4 did not act as an electronic medium to promote the electron transfer from TC to PDS. The degradation products were identified by LC-MS and the possible degradation pathways of TC were put forward. Furtherly, the decontamination of natural actual water (tap water, secondary effluent and river water) spiked with TC were evaluated.
查看更多>>摘要：Superhydrophobic membranes have been playing crucial role in efficient remediation of organic pollutants contaminated water, especially for oily discharged wastewater. Taking advantages of the inherent features of graphene oxide (GO), sodium alginate (SA) and lignin, a novel type of superhydrophobic biopolymer aerogel membrane (T-SA/lignin~x/rGO-MTMS) was prepared by freeze-casting technique and subsequent chemical vapor deposition, during which trimethoxymethylsilane (MTMS) silylation growth was achieved for the supreme protuberance, leading to the formation of rough and hydrophobic surface that favorably looks like a hedgehog carrying apples. Due to the air cushion induced by cooperative interaction between rough lignin particles and SA of 3D porous network with gas as a dispersion medium, and crumpled GO nanosheets, as-fabricated membrane with integrated functions of biopolymers possessed superhydrophobic surface characteristics (WCA = 161°), 1 More favorably, utilizing the inherent molecular features, lignin has been successfully employed to de-oxidize GO during this preparative concept. By virtue of the low-surface-energy reduced GO (rGO) and abundant protuberance, T-SA/lignin~x/rGO-MTMS exhibited potential cycling performance even with 10 cycles of oil/water separation and oil sorption. This study might shed light on the value-added utilization of integrated functions of biopolymers for designing task-specific functional materials for various applications.
查看更多>>摘要：Conventional flocculants are difficult to effectively remove dissolved ions and organic matter from water. This work aims to develop an environmentally friendly and renewable core-shell type flocculant (MCHS-g-P(AM-IA)) with octopus tentacle-like strong adsorption structure. The organic shell hydrolyses into molecular chains like octopus tentacles and adsorb dissolved ions/organic macromolecules through suckers-like functional groups while the magnetic core acts as the growth center of floes. Configuration and physical/chemical properties of the flocculant were analyzed by a series of characterization methods. Set Cu(II) and malachite green (MG) as models of heavy metal and organic pollutants separately, the removal capacity of MCHS-g-P(AM-IA) for water contaminants was studied in single-contaminant system and binary-contaminant system. The flocculation behavior and mechanism of MCHS-g-P(AM-IA) were deeply investigated by analysis of pH-dependence, background cationic influence and flocculation kinetics and SEM-EDS/XPS analysis of floes. Furthermore, the flocculation performance in actual water matrix and regeneration tests of MCHS-g-P(AM-IA) were carried out to evaluate the applicable feasibility of flocculants for purification of complex wastewater in single stage water treatment.
查看更多>>摘要：An environmentally friendly magnetic biochar was successfully prepared for the efficient removal of uranium(VT) from wastewater. The results of batch adsorption experiments showed that the uranium(VI) removal on the magnetic biochar was almost independent on the ion strength and ion species. After five cycles, the removal percentage of uranium(VI) on the magnetic biochar still exceeded 90%, which displayed that the magnetic biochar possessed excellent reusability for removing uranium(VT). It was worth mentioning that the biochar-based adsorbents were easy to be recovered from solution after doping magnetic iron oxide into biochar. Besides, the as-prepared magnetic biochar could effectively (95.2%) remove uranium(VI) with a high adsorption capacity (662.5 mg/g), which was far superior to other biochar-based adsorbents. In a word, it was expected that this investigation would provide a green treatment method for the excess of cow manure and an ideal adsorbent for removing uranium(VI) from wastewater.CapsuleThe magnetic biochar with excellent adsorption properties were prepared via environment friendly method.
查看更多>>摘要：Supercritical CO2 (ScCO2) is widely used in the extraction of natural organic compounds because of its superior solubility and high selectivity. Thermal diffusion is a method of separating substances based on temperature gradient, which has been applied to the separation of isotopes. A new process for the separation of alcohol hydrocarbon azeotropes by supercritical CO2 and thermal diffusion coupling was proposed in this paper. Taking five binary azeotropic systems of ethanol-n-hexane, etiianol-n-heptane, isopropanol-n-hexane, isopropanol-n-heptane and nonanol-n-dodecane as the research objects, the best process for separating alcohol hydrocarbon azeotropes by ScCO2 coupled thermal diffusion was explored. The results showed that the process can effectively separate the above five binary alcohol hydrocarbon mixture systems. The optimum process operating conditions were as follows: the separation time was 180 min, the separation pressure was >9 MPa, the temperature difference between the two walls was 70-80 °C, and when the separation effect of each system was greater than 90%, the continuous separation times of the system was ethanol-n-hexane for 3 times; Ethanol-n-heptane, 4 times; Isopropanol-n-hexane, 4 times; Isopropanol-n-heptane, 5 times.
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