Effect Of Pore Forming Agent Research Articles

Effect of pore-forming agent on degradation of phenol by iron tailings based porous ceramics

In order to realize the resource utilization of solid waste and the treatment of phenol wastewater in China, a new porous ceramic granules (PCG) with the function of degrading phenol wastewater was prepared by using titanium-containing blast furnace slag, iron tailings and fly ash as raw materials, which realized the sustainable development of "treating waste with waste". The effects of different pore forming agents on the structure, morphology, ionic state of PCG samples and the adsorption behavior of phenol in aqueous solution were investigated. The results show that the change of pore forming agent has no obvious change on the crystal structure. When carbon powder (CP) and starch (SH) are used as pore forming agents, the internal pore structure is relatively dense and less porous, and it is not easy to form liquid channels. When ammonia bicarbonate (NH) is used as pore-forming agents, the internal pore structure is very developed and has many three-dimensional pore structures. Under the conditions of PH 2, phenol concentration 10 mg/L and solid-liquid ratio 3 g/L, TOC removal rates of CP-PCG, SH-PCG and NH-PCG samples after 72 h adsorption reaction were 39.10 %, 14.00 % and 93.29 %, respectively. In addition, the surface functional groups, hydrogen bonds and π-π interactions of PCG samples may be involved in the adsorption of phenol. This work not only provides a low-cost, environmentally friendly and simple technology for phenol-containing wastewater treatment, but also provides a new idea for the effective use of solid waste resources.

Porous ceramic membranes from coal fly ash with addition of various pore-forming agents for oil-in-water emulsion separation

Coal fly ash (CFA) is a substitute material for ceramic membrane which can effectively reduce the preparation cost. However, CFA based ceramic membranes usually show insufficient mechanical strength for application. Revealing pore-forming mechanisms of different pore-forming agents in membranes preparation is of great significance to improve mechanical strength without harming permeability. In this work, three different pore-forming agents, carbon powder, dolomite and dextrin, were adopted to prepare CFA membranes. Characters including porosity, pore size distribution and permeability of membranes were comparatively analyzed. Effects of pore-forming agents on membranes were discussed. The membrane with dextrin at 1200 °C sintering showed the best comprehensive properties. Its porosity, flexural strength and Darcian permeability coefficient were 39.46 %, 35.56 MPa and 3.84 × 10−14 m2, respectively. Application in oil-in-water emulsion separation indicated higher than 94 % oil rejection. This research provides experimental bases for improving performances of low-cost CFA membranes, thereby conducive to engineering applications.

Fabrication of Porous Carbon Nanofibers from Polymer Blends Using Template Method for Electrode-Active Materials in Supercapacitor

Porous carbon nanofibers (PCNFs) with excellent physical and chemical properties have been considered candidate materials for electrodes used in supercapacitors. Herein, we report a facile procedure to fabricate PCNFs through electrospinning blended polymers into nanofibers followed by pre-oxidation and carbonization. Polysulfone (PSF), high amylose starch (HAS), and phenolic resin (PR) are used as three different kinds of template pore-forming agents. The effects of pore-forming agents on the structure and properties of PCNFs have been systematically studied. The surface morphology, chemical components, graphitized crystallization, and pore characteristics of PCNFs are analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and nitrogen adsorption and desorption test, respectively. The pore-forming mechanism of PCNFs is analyzed by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Fabricated PCNF-R have a specific surface area as high as ~994 m2/g, a total pore volume as high as ~0.75 cm3/g, and a good graphitization degree. When PCNF-R are used as active materials to fabricate into electrodes, the PCNF-R electrodes show a high specific capacitance ~350 F/g, a good rate capability ~72.6%, a low internal resistance ~0.55 Ω, and an excellent cycling stability ~100% after 10,000 charging and discharging cycles. The design of low-cost PCNFs is expected to be widely applicable for the development of high-performance electrodes for an energy storage field.

Study on preparation process parameters and tribological properties of porous PI materials

PurposePreviously, the effect of pore-forming agents on the properties of pore size and morphology was studied. In this paper, we determine the optimal combination of parameters by tensile strength and perform tribological tests with optimal combination of parameters.Design/methodology/approachIn this paper, porous polyimide (PI) materials were fabricated using vacuum hot molding technology. The orthogonal experiment was designed to test the mechanical properties of porous PI materials with the process parameters and the content of pore-forming agent as the changing factors. The porous PI oil-bearing materials were obtained by vacuum immersion, and tribological test were carried out.FindingsThe results showed that porous PI oil-bearing materials are suitable for low-speed and low-load conditions. The actual value of the friction coefficient basically match with the theoretical value of the regression analysis, and the errors of the friction coefficient are within 10% and 3%, respectively, which proves that the method used in the study is feasible for the friction coefficient prediction.Originality/valueIn this paper, we have produced a new porous oil-bearing material with good tribological properties. This study can effectively predict the friction coefficient of PI porous material.

Utilization of hemihydrate phosphogypsum for the preparation of porous sound absorbing material

Phosphogypsum (PG) as an industrial by-product of phosphoric acid production causes severe environmental pollution. Beta-hemihydrate phosphogyspum (β-HPG) obtained by low temperature calcination of PG can be used for the preparation of functional building materials to achieve its utilization. This work aims to utilize β-HPG as raw material for the preparation of porous sound absorbing material (PSAM). The effects of pore-forming agent, basalt fiber and expanded perlite on the properties of PSAM were investigated systematically by the analyses of sound absorption coefficient, mechanical strength, bulk density, open porosity and microstructure. In addition, the sound absorption properties of PSAM were evaluated by noise reduction coefficient in accordance with the corresponding Chinese standard. The results show that pore-forming agent and basalt fiber can form a large number of interconnected pores in the PSAM, and expanded perlite can further increase the sound absorption properties of PSAM by the combination of interconnected pore structure and cavity resonance sound absorption structure. High efficiency sound absorbing material can be prepared with 0.6 wt% pore-forming agent, 1 wt% basalt fiber and 6 wt% expanded perlite by the weight of β-HPG. This work provides an effective and high value-added way for the utilization of PG.

Xylan-Based Hydrogels as a Potential Carrier for Drug Delivery: Effect of Pore-Forming Agents.

Pore-forming agents have a significant influence on the pore structure of hydrogels. In this study, a porogenic technique was employed to investigate the preparation of macroporous hydrogels which were synthesized by radical copolymerization of carboxymethyl xylan with acrylamide and N-isopropylacrylamide under the function of a cross-linking agent. Six kinds of pore-forming agents were used: polyvinylpyrrolidone K30, polyethylene glycol 2000, carbamide, NaCl, CaCO3, and NaHCO3. The application of these hydrogels is also discussed. The results show that pore-forming agents had an important impact on the pore structure of the hydrogels and consequently affected properties of the hydrogels such as swelling ratio and mechanical strength, while little effect was noted on the thermal property of the hydrogels. 5-Fluorouracil was used as a model drug to study the drug release of the as-prepared hydrogels, and it was found that the drug release was substantially improved after using the NaHCO3 pore-forming agent: a cumulative release rate of up to 71.05% was achieved.

Effects of Pore-Forming Agent on Characterization of NiO/YSZ Porous Anode for SOFC

A comparative study has been carried out on the effects of pore-forming agents on the microstructural characteristics and properties including porosity, microstructures, linear sintering shrinkage and mechanical strength of NiO/yttria stabilized zirconia (YSZ). Different pore-forming agents (soluble starch, graphite and activated carbon) were incorporated into NiO/YSZ at various mass mixing ratios (5%, 10% and 15%). The experimental results show that under the condition of same content, sintered samples using activated carbon as pore-forming agent had a higher porosity than that with identical content of the other two kinds of pore-forming agents. Sintered samples with 10.0 wt% activated carbon had a porosity of 35%. Section morphologies show that pores distributed uniformly and connected very well in the anode with activated carbon as pore-forming agent. The mechanical strength of these sintered samples with carbon as pore-forming agent was also higher. With the activated carbon particle size decreasing (from 100 mesh to 320 mesh), the open porosity of porous NiO/YSZ was reduced (from 31.7% to 30.9%). It may be concluded that The activated carbon is the better choice as pore-forming agent for NiO/YSZ anode.

Effect of Pore-Forming Agent on Porous Mullite Ceramics from Pyrolysis of Alumina Powders Filled Silicone Resin

Mesoporous and macroporous mullite ceramics were fabricated from pyrolysis of alumina nanopowders filled silicone resin. The effect of pore-forming agent (carbon nanopowders) on the pore structure and mechanical property of the porous mullite ceramics were investigated. By varying the carbon content, the porosity and flexural strength of the obtained ceramics could be easily tuned. Both of the open porosity and average pore size of the obtained samples increased at elevated carbon content, and reached the maximum value of 61.0%, 225.5 nm respectively when the carbon content got the highest point (40 Vol.%). The flexural strength of nanoporous mullite ceramics changed almost with an opposite trend of open porosity, with the biggest value of 36 MPa when 10 Vol.% carbon was adopted. The microstructure of porous mullite ceramics consists of dense region and loose region when the added carbon content was at relatively low level. However, the dense area gradually disappeared with the increasing of carbon content.

Effect of Pore-forming Agent on Porous Reaction-bonded Silicon Nitride Ceramics

Porous reaction-bonded silicon nitride(RBSN) ceramics were fabricated by using potassium chloride(KCl) and urea(CO(NH2)2) as pore-forming agent, respectively. Green bodies with 30% in mass KCl were subjected to presinter in Ar atmosphere at 1200°C and then reaction-sintered. The properties of porous silicon nitride ceramics adding different pore-forming agent were explored. And the influence of presintering on apparent porosity, bulk density and bending strength of porous ceramics were investigated. The results indicated that the porosity of Si3N4 ceramics showed a nearly linear increase as the content of KCl increasing, but urea was not. And after presintering, the porosity had small decrease, but bending strength increased obviously. Low bulk density with about 58.6% porosity Si3N4 ceramic was prepared by adding 50wt% KCl, and the main phase composition of porous ceramic was α-Si3N4. Lots of needle-liked α-Si3N4, especially in the pores, could be observed.

Preparation of Controlled Microporous High Speed Steel and its Composite Self-Lubrication Materials

High speed steel (HSS) with controlled micropores was prepared via vacuum sintering process, using the mixture of stearic acid, TiH2 and CaCO3 compound as pore-forming agent. A self-made vacuum high pressure infiltration furnace was used to infiltrate the preform with 60Pb40Sn40-15Ag-0.5RE solid lubricants to create self-lubrication composite where both solid lubricant phase and matrix phase were interpenetrating throughout the microstructure. Effects of pore-forming agent on micropore structure and porosity of the prepared microporous HSS preforms were investigated. The scanning electron microscope (SEM) observation was applied to the test samples and it revealed that the micropores of the microporous materials exhibited a uniform distribution and the apertures were of almost same size in principle. The friction and wear behaviors of the composite sliding against ZrO2 ceramic under a load of 50 N at 600 °C were investigated using a pin-on-disk wear tester and the results showed that this kind composite possessed excellent high temperature self-lubrication properties.

Effect of Pore-Forming Agents on Structure and Properties of PVDF/PVC Blend Membranes

By phase inversion process, the polyvinylidene fluoride (PVDF) with polyvinyl chloride (PVC) blend membrane was prepared. In which, as pore-forming agents, the polyethylene glycol (PEG), poly(vinylpyrrolidone) (PVP) and lithium chloride (LiCl) was separately added into PVDF/PVC casting solution. The effect of each pore-forming agent on the kinetics of membrane formation and properties of PVDF/PVC blend membrane were investigated respectively. Using the capillary flow porometry, the microstructure and morphology of PVDF/PVC blend membrane were quantitatively characterized. The results show that by respectively adding PEG, PVP or LiCl, it emphasizes the rate of solvent diffusion from PVDF/PVC solution during the phase inversion or membrane formation, and the porosity of membrane gets increasing. The pure water flux of PVDF/PVC blend membrane achieves enhancement obviously. At the same time, the rejection is decreased in a certain degree. Comparison with PEG or LiCl, PVP has more effect on the membrane pore-forming action. The microstructure analysis indicates that based on the same formulation, by selecting PEG or LiCl as pore-forming agent, formatted PVDF/PVC blend membranes achieve equivalent mean pore size. However, there is a little larger mean pore size distributed in the membrane by using PVP instead of PEG or LiCl. The application of purifying ε-polylysine (ε-PL) by using the PVDF/PVC blend membrane with PVP, the results reveal that the protein removal rate can be around 62.33% and the filterable and permeated ε-PL kept at 70.79% yield.

Fabrication and evaluation of asymmetric membrane osmotic pump

Asymmetric membrane-controlled porosity osmotic pumps of cellulose acetate with different pore forming agents such as glycerol, polyethylene glycol and dibutyl phthalate, were fabricated and studied for osmotic release behavior from the system. The effects of various pore-forming agents on the physical characteristics of the polymer film like tensile strength, weight variation, wall thickness, surface area, porosity and void volume were studied as a function of pore forming agent. The asymmetric membrane capsules were fabricated by dip-coating process using stainless steel mold pins of the shape of capsule body and cap and were evaluated for in situ formation of delivery pores. The effect of pore forming agents on the porosity of asymmetric membrane was characterized by scanning electron microscopy, and also by void volume determination of each membrane. Dye-test revealed that the fabricated systems followed osmotic release. Scanning electron microscopy revealed that the porosity depends upon the concentration and type of pore forming agent used. However no significant effect on the thickness and weight variation of asymmetric membrane capsule were observed, but the tensile strength of the film varied with the concentration and type of pore forming agent used. Film with polyethylene glycol-400 as pore forming agent exhibited good tensile strength.

Effect of pore-forming agent on PTCR characteristics of n-BaTiO3

Porous n-BaTiO3 ceramics are synthesized by the addition of pore-forming agent into the (Ba,Sr)TiO3 powder. From the DTA-TGA analysis for samples containing the PEG and corn-starch, it was found that an exotherm occurred at 262 and 315°C, respectively, weight loss commenced at 165 and 252°C, and was virtually complete by 265 and 472°C, respectively. The porosity of n-BaTiO3 ceramics increased and the grain size decreased with increasing the pore-forming agent. From the XRD analysis at high angles, all the samples with and without the pore-forming agent at room-temperature exhibit the tetragonal structure. PTCR jump of the samples containing pore-forming agent is 1-2 orders higher than that of sample without the pore-forming agent. It is also found that the development of PTCR characteristic in the porous n-BaTiO3 ceramics containing pore-forming agent is related to grain boundaries, which basically equals that in ordinary BaTiO3 without pore-forming agent, from the complex impedance results.