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Shui Lin Zheng - One of the best experts on this subject based on the ideXlab platform.
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Facile fabrication of g-C3N4/Precipitated Silica composite with enhanced visible-light photoactivity for the degradation of rhodamine B and Congo red
Advanced Powder Technology, 2016Co-Authors: Chunquan Li, Xue Li, Shui Lin ZhengAbstract:Abstract Novel g-C3N4/Precipitated Silica (CN/PS) composite with high visible-light activity was successfully synthesized through a facile wetting chemical method. The microstructure, interfacial and optical properties of the obtained CN/PS composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), surface area measurement (BET), UV–visible diffused reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). It is indicated that the tight interfacial interaction was formed between g-C3N4 nanosheets and Precipitated Silica nanoparticles, which is beneficial for the transfer of electrons and the enhancement of quantum efficiency. The synthesized CN/PS composites exhibited significantly enhanced photoactivity under visible light no matter towards rhodamine B (RhB) or Congo red (CR). Especially for the RhB degradation, the highest rate constant of CN/PS composite was up to around 10 times as much as that of pure g-C3N4. The enhancement mechanism could be mainly attributed to the enhanced adsorption capacity, stronger visible light adsorption as well as the defect or vacancy sites provided by the Precipitated Silica nanoparticles.
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facile fabrication of g c3n4 Precipitated Silica composite with enhanced visible light photoactivity for the degradation of rhodamine b and congo red
Advanced Powder Technology, 2016Co-Authors: Chunquan Li, Xue Li, Shui Lin ZhengAbstract:Abstract Novel g-C3N4/Precipitated Silica (CN/PS) composite with high visible-light activity was successfully synthesized through a facile wetting chemical method. The microstructure, interfacial and optical properties of the obtained CN/PS composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), surface area measurement (BET), UV–visible diffused reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS). It is indicated that the tight interfacial interaction was formed between g-C3N4 nanosheets and Precipitated Silica nanoparticles, which is beneficial for the transfer of electrons and the enhancement of quantum efficiency. The synthesized CN/PS composites exhibited significantly enhanced photoactivity under visible light no matter towards rhodamine B (RhB) or Congo red (CR). Especially for the RhB degradation, the highest rate constant of CN/PS composite was up to around 10 times as much as that of pure g-C3N4. The enhancement mechanism could be mainly attributed to the enhanced adsorption capacity, stronger visible light adsorption as well as the defect or vacancy sites provided by the Precipitated Silica nanoparticles.
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Study on Preparation and Photocatalytic Activity of Nano-TiO2/Precipitated Silica Composite Material
Applied Mechanics and Materials, 2013Co-Authors: Fang Hui Lu, Shui Lin Zheng, Bing Song, Zong Yi YangAbstract:Using Precipitated Silica as the carrier, a kind of composite photocatalyst was prepared through hydrolysisde positing method. The obtained composite material was characterized by XRD, SEM, TEM, FT-IR. Based on the experimental results and analysis of characterization, the preparation mechanism of composite powder material was studied. The photocatalytic degration experiment of Rhodamine-B indicates that the Precipitated Silica is an ideal carrier of the TiO2,and the photocatalyst can combine with the Silica tightly. The photocatalytic activity of the obtained composite material is stabilize and constant.
Avraam I. Isayev - One of the best experts on this subject based on the ideXlab platform.
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Rheology and structure of Precipitated Silica and poly(dimethyl siloxane) system
Rheologica Acta, 2004Co-Authors: Sang Eun Shim, Avraam I. IsayevAbstract:The reinforcing capability of Precipitated Silica in poly(dimethyl siloxane: PDMS) was characterized by means of bound rubber formation, solvent swelling, yield stress, rheological and dynamic properties. Volume concentration of Precipitated Silica in PDMS was varied from 0 to 0.16. The homogeneity of the compounds after mixing was confirmed by studying a uniformity of dispersion of Silica particles in PDMS via SEM morphology of vulcanizates. Bound rubber measurements of the compounds and solvent swelling studies of vulcanizates showed that the Precipitated Silica exhibited much stronger interaction with PDMS than that of typical carbon black with rubbers but less than that of fumed Silica with PDMS. At high volume concentrations of Silica (0.128 and 0.160), a yield behavior was evident from the storage modulus measurements. The network formation due to an interaction between the Precipitated Silica and PDMS was visualized via dynamic property measurements.
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ultrasonic devulcanization of Precipitated Silica filled silicone rubber
Rubber Chemistry and Technology, 2001Co-Authors: Sang E. Shim, Avraam I. IsayevAbstract:Abstract This investigation involves the recycling of Precipitated Silica-filled silicone rubber using a continuous ultrasonic reactor. The processing conditions utilized in devulcanization of the filled systems were similar to those in our previous work on unfilled systems. Significant differences were observed in devulcanization of unfilled and filled systems. A decrease in gel fraction and crosslink density was sufficient for devulcanized Silica-filled silicone rubber to be reprocessed and revulcanized. The cure behavior of silicone rubber and the mechanical properties of virgin, and revulcanized rubber were measured. Results showed that unfilled silicone rubbers gave no change in vulcanizate mechanical properties after revulcanization. However, in the filled rubbers there was a decrease in the mechanical properties of revulcanizates. In order to achieve an improvement in the properties, devulcanized filled rubbers were blended with virgin filled rubber in various proportions. The obtained results indi...
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Ultrasonic Devulcanization of Precipitated Silica-Filled Silicone Rubber
Rubber Chemistry and Technology, 2001Co-Authors: Sang E. Shim, Avraam I. IsayevAbstract:This investigation involves the recycling of Precipitated Silica-filled silicone rubber using a continuous ultrasonic reactor. The processing conditions utilized in devulcanization of the filled systems were similar to those in our previous work on unfilled systems. Significant differences were observed in devulcanization of unfilled and filled systems. A decrease in gel fraction and crosslink density was sufficient for devulcanized Silica-filled silicone rubber to be reprocessed and revulcanized. The cure behavior of silicone rubber and the mechanical properties of virgin, and revulcanized rubber were measured. Results showed that unfilled silicone rubbers gave no change in vulcanizate mechanical properties after revulcanization. However, in the filled rubbers there was a decrease in the mechanical properties of revulcanizates. In order to achieve an improvement in the properties, devulcanized filled rubbers were blended with virgin filled rubber in various proportions. The obtained results indicated a considerable enhancement of the performance characteristics of these blend vulcanizates.
Dang Viet Quang - One of the best experts on this subject based on the ideXlab platform.
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Preparation of Polyethylenimine Impregnated Mesoporous Precipitated Silica for CO2 Capture
Proceedings of the 4th International Gas Processing Symposium, 2015Co-Authors: Dang Viet Quang, Nabil El Hadri, Aravind V. Rayer, Mohammad R.m. Abu-zahraAbstract:Abstract In this study, a novel and inexpensive CO 2 adsorbent has been prepared by impregnating polyethyleneimine (PEI) onto mesoporous Precipitated Silica. The study indicates that the CO 2 adsorption capacity of the prepared adsorbent increases with the increase in PEI loading. The maximum adsorption capacity of adsorbent can be achieved at 75 o C. In pure CO 2 , at 75 o C and 1 bar, adsorbent containing 60% PEI can adsorb 199.6 mg of CO 2 /g. The adsorption capacity of an adsorbent impregnated with 55% PEI (PEI-MPS-55) measured at the heat equilibrium reduced from 128 mg/g to 117 mg/g and 101 mg/g as CO 2 concentration varies from 100 to 15% and 4%, respectively. The adsorption heat calculated ranges from 68─75 kJ/mole of CO 2 . The cyclic adsorption-desorption studies revealed that the adsorbent is relatively stable; the CO 2 loading was not changed after 20 cycles of adsorption/regeneration at 75/90 o C. Keywords : Adsorption capacity; CO 2 capture; Regeneration; Adsorbent; Precipitated Silica.
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effect of moisture on the heat capacity and the regeneration heat required for co2 capture process using pei impregnated mesoporous Precipitated Silica
Greenhouse Gases-Science and Technology, 2015Co-Authors: Dang Viet Quang, Abdurahim Abdulkadir, Nabil El Hadri, Aravind V. Rayer, Abdallah Dindi, Mohammad R M AbuzahraAbstract:In this study, we report the effect of the moisture of polyethylenimine (PEI) impregnated mesoporous Precipitated Silica used for CO 2 adsorption on the heat capacity and the heat required to regenerate the adsorbent. The results indicate that the heat capacity of the absorbent increases as its moisture content increases. The increase in moisture results in the rise of the vaporization heat of water and the elevated heat capacity results in higher sensible heat. For these reasons, the total regeneration heat required for CO 2 capture process increases significantly. The adsorbent has a maximum CO 2 adsorption capacity at 75 °C. CO 2 capture process using PEI impregnated mesoporous Precipitated Silica requires a minimum energy to regenerate the adsorbent; it reduces 46% of the energy compared to a process using an aqueous MEA 30 wt%, as the process operates at 75 °C.
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impregnation of amines onto porous Precipitated Silica for co2 capture
Energy Procedia, 2014Co-Authors: Dang Viet Quang, Abdurahim Abdulkadir, Nabil El Hadri, Aravind V. Rayer, Abdallah Dindi, Mohammad R M AbuzahraAbstract:Abstract In this study, porous Precipitated Silica (PPS) was synthesized using sodium Silicate as an inexpensive Silica precursor and then impregnated with various amines such as 2-aminomethylpropanol (AMP), monoethanolamine (MEA), diethanolamine (DEA) and polyethyleneimine (PEI) to produce amine-impregnated solid adsorbents, which will be evaluated as a sorbent for CO 2 capture. Major parameters and performances of adsorbents including thermal stability, adsorption capacity, heat capacity, and adsorption heat were investigated. The results indicated that MEA impregnated PPS (60 wt%) has the highest CO 2 adsorption capacity; up to 233 mg/g, while the adsorption capacity of PEI impregnated PPS (60 wt%) is 136 mg/g. The heat capacity of PEI impregnated PPS (50 wt%) is relatively low (1.68 J/g C) compared to that of aqueous MEA 30 wt% (3.98 J/go·C). Obtained results were used to calculate the energy requirement for adsorbent regeneration. The calculated results revealed that PEI impregnated PPS (50 wt%) requires the least energy for regeneration, only 2080 kJ/kg of CO 2 and it is 44.7% lower than energy requirement for aqueous MEA 30 wt%. Thermal stability of the adsorbents was confirmed by thermal gravity analyses, which showed that AMP and MEA start vaporizing at very low temperature and complete at 110 and 120 oC, DEA vaporizes at temperature from 100 200oC, and PEI vaporizes and decomposes at about 250 400 oC. The study on adsorption/desorption performance at the regeneration temperature of 90 oC indicated that the stability of the sorbent is greatly varied with the vaporization temperature. PEI impregnated PPS shows a no significant loss in CO 2 adsorption capacity, while DEA impregnated PPS lost 12% of adsorption capacity after 10 cycles.
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reduction in the regeneration energy of co2 capture process by impregnating amine solvent onto Precipitated Silica
European Scientific Journal ESJ, 2013Co-Authors: Dang Viet Quang, Nabil El Hadri, Aravind V Rabindran, Mohammad R M AbuzahraAbstract:High energy required for the regeneration of aqueous amine solution is a great challenge for conventional CO2 capture technology to be deployed on large scale. Finding novel adsorbent with low regeneration energy and cost-effectiveness for CO2 capture is an impetus for researchers. In this study, Precipitated Silica (PS) was synthesized and impregnated with various amines including 2-aminomethylpropanol (AMP), monoethanolamine (MEA), diethanolamine (DEA) and polyethyleneimine (PEI) to produce solid adsorbents. The CO2 adsorption capacity, heat capacity, and adsorption heat of adsorbents were determined. The results were used to calculate the regeneration heat of CO2 adsorption process, which then was compared with the conventional aqueous MEA 30 wt% based process. The results indicated that MEA impregnated PS (60 wt%) has the highest CO2 adsorption capacity; up to 5.3 mmole/g and PEI impregnated PS (50 wt%) has the lowest adsorption capacity among prepared solid adsorbents; 2.9 mmole/g, which is, however, higher than that of aqueous MEA 30 wt% (2.7 mmole/g). The regeneration heat required for the solid adsorbents substantially decreased in comparison with aqueous MEA 30 wt%. Regeneration heat required for PEI impregnated PS (50 wt%) was 2080 kJ/kg of CO2 that is 46.7% lower than that of aqueous MEA 30 wt%. The obtained results demonstrated that the impregnation of amine onto PS is a viable method to reduce the regeneration energy of CO2 capture process.
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effect of the gelation on the properties of Precipitated Silica powder produced by acidizing sodium Silicate solution at the pilot scale
Chemical Engineering Journal, 2012Co-Authors: Dang Viet Quang, Jinkoo Park, Seokhoon Park, Gideon Elineema, Pradip B SarawadeAbstract:Controlling the properties of Precipitated Silica (PS) synthesized by acidizing sodium Silicate solution is a significant challenge. Here, we report the effect of gelation on the BET surface area and pore volume of the PS produced at the pilot scale. H2SO4 was added to a mixture of sodium Silicate and sodium chloride in two stages: the first stage ends before the gelation point and the second one ends as pH of solution reached to 5. The interval (Δt) from the end of the first stage to the gelation point was recorded to evaluate its effect on the properties of the resulting PS. The obtained samples were characterized by nitrogen adsorption–desorption method, field emission scanning electron microscopy (FE-SEM), and field emission scanning transmission electron microscopy (FE-STEM). The results revealed that the BET surface area and pore volume of the prepared PS decreases with the increase of Δt and temperature, while the pore size is not affected. The variations in the properties of the PS were successfully explained by the application of a percolation model to the flocculation and bridging of the primary particles.
Hongliang Xu - One of the best experts on this subject based on the ideXlab platform.
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properties of vulcanized rubber nanocomposites filled with nanokaolin and Precipitated Silica
Applied Clay Science, 2008Co-Authors: Yude Zhang, Hongliang XuAbstract:Abstract One kind of nanokaolin (NK) powder with 20–50 nm average thickness, 300–500 nm average diameter, and 32 m 2 /g specific surface area, has been introduced into four types of rubber, specifically styrene butadiene rubber (SBR), natural rubber (NR), butadiene rubber (BR) and ethylene–propylene diene methylene (EPDM). Their reinforcing effects were evaluated by comparisons with those from Precipitated Silica (PS). The curability, mechanical properties, microstructure and the thermal stability of a variety of composites based on these rubbers were studied. This was done using vulcanization techniques, mechanical testing, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that NK can greatly improve the vulcanizing process by shortening the time to optimum cure ( t 90 ) and prolonging the setting-up time ( t 10 ) of cross-linked rubbers, which improves production efficiency and operational security. The rubber composites filled with nanokaolin were found to have good mechanical properties, thermal stabilities, and elastomeric properties. The tensile strengths of the rubber/NK composites are close to those of rubber/PS composites, but the tear strength and modulus are not as good as the corresponding properties of those containing Precipitated Silica. Microstructural results revealed that the NK sheets are well dispersed in the rubber matrix in the parallel arrangement. The good interfacial interactions between the NK and the rubber chains give these rubber composites excellent processability, mechanical properties, and thermal stability.
Lin Ye - One of the best experts on this subject based on the ideXlab platform.
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structure and property of polyvinyl alcohol Precipitated Silica composite hydrogels for microorganism immobilization
Composites Part B-engineering, 2014Co-Authors: Yi Zhang, Lin YeAbstract:Abstract Polyvinyl alcohol (PVA) hydrogel filled with Precipitated Silica (PSi) was prepared by chemical crosslinking in the saturated boric acid solution. The structure and property of the composite hydrogel was studied. It was found that PSi could accelerate the crosslinking reaction of PVA, and the intermolecular bonding of PVA/PSi composite was confirmed. Effect of PSi on reactive kinetics of PVA hydrogel was investigated. The tensile strength of PVA hydrogel increased with PSi content. Proper content of PSi could also enhance the permeability and swelling property, resulting in the improvement of the capillary water absorption capacity of PVA hydrogel. By addition of PSi, many large pores formed in the hydrogel so as to provide channels for microbial metabolites. When being applied in waste water treatment, the value of oxygen uptake rate (OUR) and COD removal rate of the PVA composite hydrogel immobilized with activated sludge increased significantly, indicating that the microbial activity of PVA immobilized beads could be enhanced.
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Structure and property of polyvinyl alcohol/Precipitated Silica composite hydrogels for microorganism immobilization
Composites Part B-engineering, 2013Co-Authors: Yi Zhang, Lin YeAbstract:Abstract Polyvinyl alcohol (PVA) hydrogel filled with Precipitated Silica (PSi) was prepared by chemical crosslinking in the saturated boric acid solution. The structure and property of the composite hydrogel was studied. It was found that PSi could accelerate the crosslinking reaction of PVA, and the intermolecular bonding of PVA/PSi composite was confirmed. Effect of PSi on reactive kinetics of PVA hydrogel was investigated. The tensile strength of PVA hydrogel increased with PSi content. Proper content of PSi could also enhance the permeability and swelling property, resulting in the improvement of the capillary water absorption capacity of PVA hydrogel. By addition of PSi, many large pores formed in the hydrogel so as to provide channels for microbial metabolites. When being applied in waste water treatment, the value of oxygen uptake rate (OUR) and COD removal rate of the PVA composite hydrogel immobilized with activated sludge increased significantly, indicating that the microbial activity of PVA immobilized beads could be enhanced.