Xiaoyi Liang

Biomolecular adsorption behavior on spherical carbon aerogels with various mesopore sizes

Spherical carbon aerogels (SCAs) with controlled particle size and mesopore size were synthesized by an emulsified sol-gel polymerization of phenol, melamine and formaldehyde. The adsorption rate and capacity of biomolecules with different molecular dimensions, including L-phenylalanine (Phe), vitamin B(12) (VB), alpha-chymotrypsin (Chy) and bovine serum albumin (BSA) onto SCAs were investigated. The mesopore size can be easily tuned in the range from 5 to 10 nm by simply adjusting catalyst concentration in the initial solution and the spherical particle size can be controlled in 50-500 microm by changing stirring speed. The as-prepared SCAs have high specific surface area (>600 m(2)/g) and large pore volume (>1 cm(3)/g). The hardness of SCAs is ca. 10 times as large as that of commercial spherical activated carbon particles. The adsorption rate of VB is strongly depended on the mesopore size and particle size, and show an increasing tread with the increase of mesopore size and the decrease of particle size. For small molecule Phe, the specific surface area is key factor to determine the adsorption capacity, but the adsorption capacity of large molecules (VB, Chy and BSA) is dependent on the pore size of SCAs, which should be suitably larger than the molecule size of biomolecules.

Preparation of polystyrene-based activated carbon spheres and their adsorption of dibenzothiophene

Polystyrene-based activated carbon spheres (PACS) were prepared by steam activation and their adsorption performance to a sulfur-containing dibenzothiophene (DBT) was studied. The textural structure of PACS was characterized by scanning electron microscopy, N2 adsorption, thermal gravimetric, and aqueous adsorption. Results showed that PACS with BET surface areas up to 979-1672m^2/g were obtained. The BET surface areas and pore volumes increased with activation time and steam flow rate except for the volume of narrow micropores (＜0.7 nm). The maximum adsorption capacity of PACS to DBT was 109.36 mg/g and the adsorption capacity was related to the volume of narrow micropores, independent of surface area and total pore volume. Irreversible adsorption existed between DBT and PACS. The larger the volume of the narrow micropores, the higher the desorption temperature and the larger the amount of sulfur retained after heating.

Effect of pore structure on the electrochemical performance of coal-based activated carbons in non-aqueous electrolyte

Abstract Anthracite was activated by NaOH to prepare high-performance activated carbons as electrodes for electric double-layer capacitors. The porous structure and electrochemical characteristics of the carbons were investigated by nitrogen sorption and electrochemical methods. The effect of pore structure on the electrochemical performance of the carbons in a 1 mol/L (C 2 H 5 ) 4 NBF 4 /propylene carbonate (PC) electrolyte was investigated. The as-prepared activated carbons exhibit large surface areas (943-2479 m 2 /g) and high-specific capacitances (57–167 F/g). The specific capacitance depends not only on the surface area, but also on the pore size distribution (PSD) of the carbon. Pores with a size of 2–3 nm are crucial for the ions to penetrate inside them for the (C 2 H 5 ) 4 NBF 4 /PC electrolyte. Specific capacitance is higher and impedance is lower for the sample with a wider PSD due to the fact that electrolyte ions could easily enter the pores.

Preparation of mesophase pitch based mesoporous carbons using an imprinting method

Abstract Mesoporous carbons (MCs) were prepared by an imprinting method, using mesophase pitch and nanometer colloidal silica solution as carbon precursors and pore generators, respectively. The effects of the type of mesophase pitch, the imprinting temperature, and the silica content on the porous properties of MCs were investigated. It was found that the pore size distributions of MCs were similar irrespective of the imprinting temperature and the amount of silica used owing to an imprinting mechanism. The mesopore volume of MCs increased with an increasing amount of silica. There existed an appropriate imprinting temperature slightly higher than the softening point of the mesophase pitch used. An easy imprinting was found for naphthalene based mesophase pitch with a low softening point and fine average particle size as compared with coal based mesophase pitch. Mesoporous carbons were provided with a specific surface area and a total pore volume of 482 m2/g and 1.62 cm3/g, respectively.

A high strength carbon nanofiber/honeycomb cordierite composite produced by chemical vapor deposition

A carbon nanofiber (CNF)/honeycomb cordierite composite with a compressive strength of 50 MPa was prepared by chemical vapor deposition, using C2H4 as the carbon source and Ni-Cu alloy as the catalyst. The CNFs with a diameter of 20-30 nm in the cells of the honeycomb interweave with each other to form a 5 μm- thick layer. The CNF content is 25.3 wt%. The Cu has remarkable effects on the particle size of the Ni-Cu alloy, which further affects the growth rate, loading level and nanostructures of the CNFs. The CNFs are not well graphitized and the insertion of the CNFs into the honeycomb can increase its compressive strength from 10 to 50 MPa.

Pitch spheres stabilized by HNO3 oxidation and their carbonization behavior

Abstract Pitch spheres were stabilized by HNO3 oxidation at room temperature using HNO3 solutions of 10, 20, 30, and 40 wt%. The chemical structure and morphology changes of the oxidized pitch spheres and their carbonized samples were investigated by FT-IR, XPS, elemental analysis, and SEM. Results showed that the pitch spheres oxidized by 30% HNO3 for 12 h could be carbonized at 900 (C to produce carbonized spheres without any change in shape. The successful carbonization can be ascribed to the contribution of nitrogen functional groups in the form of −NO2, which were introduced in the HNO3 oxidation process. In the early stage of the heat treatment around 400 (C, the transformation of −NO2 groups to amine groups occurred, which promoted the cross-linking of pitch molecules. As the pitch spheres were carbonized at 900 (C, cyclization and aromatization reactions led to the formation of pyridine and quaternary nitrogen groups.

Modelling and optimization of the pore structure of carbon aerogels using an artificial neural network

An intelligent simulation method for predicting and optimizing the pore structure of carbon aerogels is proposed by using an artificial neural network (ANN) algorithm. The ANN model has been optimized based on an improved genetic algorithm from six typical training algorithms. The volumes and diameters of pores in the simulated samples are predicted by the optimized ANN model, which shows correlation coefficients R2 of 0.992 and 0.981 and root-mean-square prediction errors (RMSPE) of 0.077 and 0.054 between the predicted and experimental values for the volumes and diameters of pores, respectively. The proposed model is expected to have practical applications in the pore structure control of carbon aerogels.

Adsorption/Desorption Performance of CO 2 on Pitch-based Spherical Activated Carbons: Adsorption/Desorption Performance of CO 2 on Pitch-based Spherical Activated Carbons

考察了沥青基球形活性炭(PSAC)的孔结构与CO 2 吸附容量间的内在关系及其脱附性能. 采用N 2 吸附法分析PSAC的孔结构, 由穿透曲线测试其对CO 2 的平衡吸附量. 实验结果表明在CO 2 /N 2 混合气氛下, 活性炭对CO 2 的吸附容量与孔径小于1nm的微孔比表面积呈线性关系; 当PSAC担载5%的三聚氰胺后, 对CO 2 (15%)的平衡吸附量由0.91mmol/g增加到1.15mmol/g, 提高了26.3%; 采用抽真空脱附时, 循环脱附效率为74.6%, 而电解吸-抽真空耦合脱附工艺可使CO 2 的循环脱附效率接近100%.The relationship between the pore structure parameter of pitch-based spherical activated carbons (PSACs) and adsorption capacity of CO2 was investigated as well as the desorption performance. The pore structure characteristics of PSACs were analyzed by nitrogen adsorption at 77K and the equilibrium adsorption amount of CO2 was determined through the breakthrough curve. The results indicated that there was a linear relationship be- tween the equilibrium adsorption amount of CO2 and the specific surface area of micropores with pore size smaller than 1 nm. When 5% melamine was coated on the surface of PSAC, the equilibrium adsorption amount of CO2 in- creased 26.3% from 0.91 mmol/g to 1.15 mmol/g. The desorption cycle efficiency of CO2 is 74.6% with Vacuum Swing Adsorption (VSA), while it can reach 100% with combined Electric Swing Adsorption (ESA) and VSA.考察了沥青基球形活性炭(PSAC)的孔结构与CO 2 吸附容量间的内在关系及其脱附性能. 采用N 2 吸附法分析PSAC的孔结构, 由穿透曲线测试其对CO 2 的平衡吸附量. 实验结果表明在CO 2 /N 2 混合气氛下, 活性炭对CO 2 的吸附容量与孔径小于1nm的微孔比表面积呈线性关系; 当PSAC担载5%的三聚氰胺后, 对CO 2 (15%)的平衡吸附量由0.91mmol/g增加到1.15mmol/g, 提高了26.3%; 采用抽真空脱附时, 循环脱附效率为74.6%, 而电解吸-抽真空耦合脱附工艺可使CO 2 的循环脱附效率接近100%.

Computational and experimental approaches for investigating membranes diffusion behavior in model diesel fuel

Genetic algorithms trained support vector regression predicting model is conducted to research diffusion behavior of methylnaphthalene and dibenzothiophene in four different membranes of polymethyl methacrylate, polymethyl acrylate, polyvinyl chloride and polyvinyl alcohol in model diesel fuel. It is found that the polyvinyl chloride is optimal membrane material for improving the diffusion selectivity of methylnaphthalene and dibenzothiophene, which demonstrates that the polyvinyl chloride membrane is favorable to the diesel fuel desulfurization. Also, molecular dynamic simulation is applied to validating the performance of genetic algorithm trained support vector regression model. The results of genetic algorithm trained support vector regression model reveal that the simulation values are well agreed with the experimental data and molecular dynamic simulation results. Meanwhile, the performance of the genetic algorithms trained support vector regression predict model is better than that of the genetic algorithms trained neural network model, which indicates that genetic algorithms trained support vector regression method offers a new prospected decision-theoretic approach to the diesel desulfurization.

Classification and Optimization Model of Mesoporous Carbons Pore Structure and Adsorption Properties Based on Support Vector Machine

Mesoporous carbons are synthesized by organic–organic self-assembly of triblock copolymer F127 and a new type of carbon precursor as resorcinol– furfural oligomers. Some factors will impact the mesoporous carbons pore structure and properties were studied. The main factors, such as the ratio of triblock copolymer F127 and oligomers, degree of polymerizstry of resorcinol–furfural oligomers, the ratio of resorcinol–furfural oligomers F/R, and their mutual relations were identified. Aimed at balancing the complex characteristic of mesoporous structure and adsorption properties, a classification and optimization model based on support vector machine is developed. The optimal operation conditions of Barret-Joyner-Halenda (BJH) adsorption cumulative volume and average pore diameter are determined by genetic algorithm support vector classification (GASVC). Verification results find that GA-SVC provides an effective method to control and optimize operation conditions and is a new promising theoretical method for material design.