Incorporating the magnetic alignment of GO composites into Pebax matrix for gas separation

The mixed matrix membranes(MMMs) were developed by incorporating graphite oxide(GO) flakes functionalized with iron oxide(Fe_3O_4) into Pebax matrix. The Pebax/Fe_3O_4–GO MMMs were used to separate CO_2/CH_4 and CO_2/N_2 gas mixture. The results showed that the MMMs with magnetic alignment presented the better gas separation performance than that of random arrangement of Pebax/Fe_3O_4–GO mixed matrix membranes. The reason was that the Fe_3O_4–GO flakes arranged magnetically in the membrane played a multiple role in improving the performance of MMMs. Firstly, under the action of the magnetic field,the magnetic alignment of Fe_3O_4–GO flakes in Pebax matrix constructed the shorter transfer path for gas molecule, increasing the CO_2 permeability. Secondly, the hydroxyl groups in GO flakes and the presence of Fe_3O_4 have stronger binding force for water, improving the CO_2 solubility selectivity. Thirdly, the better interaction between the magnetic alignment of GO composites and polymer matrix, reduced the interface defects. Especially, the optimum gas separation performance was obtained at the Fe_3O_4–GO flakes content of 3 wt% in Pebax matrix at vertical arrangement with selectivity of 47 and 75 for CO_2/CH_4 and CO_2/N_2, respectively, and CO_2 permeability of 538 Barrer at 0.2 MPa and room temperature.

Preparation and adsorption performance of multi-morphology H_(1.6)Mn_(1.6)O_(4) for lithium extraction

In this paper,a lithium-ion sieve(LIS)with different morphologies,such as rod-like(LIS-R),spherical(LIS-S),flower-like(LIS-F),and three-dimensional macroporous-mesoporous(LIS-3D),was prepared by hydrothermal synthesis,solid reaction,and hard-template synthesis.The results showed that the LIS with different morphologies presented great differences in specific surface area,pore volume,adsorption selectivity,and structure stability.LIS-3D with highest specific surface area and pore volume displayed the maximum adsorption capacity and adsorption rate,but the stability of LIS-3D was poor because of the manganese dissolution.By comparison,LIS-S has the best structural stability while maintaining a satisfactory adsorption capacity(35.02 mg·g^(-1))and adsorption rate.The LIS-S remained about 90%of the original adsorption capacity after five cycles of adsorption-desorption process.In addition,in the simulated brine system(the magnesium to lithium ratio of 400),the LIS-S exhibited the highest selectivity(α_(Mg)^(Li))of 425.14.In sum,the LIS-S with good morphology is a potential adsorbent for lithium extraction from brine.

Solubility and mass transfer of H2, CH4, and their mixtures in vacuum gas oil: An experimental and modeling study

In this work,the solubility data and liquid-phase mass transfer coefficients of hydrogen(H2),methane(CH4)and their mixtures in vacuum gas oil(VGO)at temperatures(353.15-453.15 K)and pressures(1-7 MPa)were measured,which are necessary for catalytic cracking process simulation and design.The solubility of H2 and CH4 in VGO increases with the increase of pressure,but decreases with the increase of temperature.Henry’s constants of H2 and CH4 follow the relation of In H=-413.05/T+5.27 and In H=-990.67/T+5.87,respectively.The molar fractions of H2 and system pressures at different equilibrium time were measured to estimate the liquid-phase mass transfer coefficients.The results showed that with the increase of pressure,the liquid-phase mass transfer coefficients increase.Furthermore,the solubility of H2 and CH4 in VGO was predicted by the predictive COSMO-RS model,and the predicted values agree well with experimental data.In addition,the gas-liquid equilibrium(GLE)for H2+CH4+VGO system at different feeding gas ratios in volume fraction(i.e.,H285%+CH415%and H290%+CH410%)was measured.The selectivity of H2 to CH4 predicted by the COSMO-RS model agrees well with experimental data.This work provides the basic thermodynamic and dynamic data for fuel oil catalytic cracking processes.

Mixed matrix membrane containing metal oxide nanosheets for efficient CO_(2)separation

The two-dimensional(2D)nanosheet zinc cobaltate(ZnCo_(2)O_(4))was added into polyether block amide(Pebax)matrix to prepare mixing matrix membrane(MMM)for separating carbon dioxide(CO_(2))/methane(CH4)gas mixture.The 2D porous ZnCo_(2)O_(4)nanosheets were composed of chemically interconnected metal oxide nanoparticles.The ZnCo_(2)O_(4)nanoparticles in the nanosheets constructed large-quantity pores of 11.78 nm and provided abundant transfer channels for gas molecule.Moreover,the synergistic effect of bimetallic Zn^(2+)and Co^(2+)would promote the generation of oxygen vacancies(Oδ-),which could provide more CO_(2)(Cδ+)adsorption sites,thereby increased the selectivity of the membrane.The large aspect ratio of the ultra-thin ZnCo_(2)O_(4)nanosheets showed better dispersion in the membrane.The pure gas separation performance data showed the CO_(2)permeability and CO_(2)/CH4 selectivity of Pebax/ZnCo_(2)O_(4)membrane were 139.10 Barrer and 15.38,respectively,when the filling amount was 0.5 wt%.Compared with pure Pebax membrane,the separation performance(permeability and selectivity)were increased with 165.67%and 75.57%,respectively.