scholarly journals The Internal Recycle Reactor Enhances Porous Calcium Silicate Hydrates to Recover Phosphorus from Aqueous Solutions

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Wei Guan ◽  
Shichao Tian
Keyword(s):  
Surface Area ◽  
Pore Volume ◽  
Calcium Silicate ◽  
Ph Value ◽  
Optimal Operation ◽  
Phosphorus Recovery ◽  
Operation Conditions ◽  
Calcium Silicate Hydrates ◽  
Recycle Reactor ◽  
Adsorption Desorption

In this experiment, the porous calcium silicate hydrates (P-CSHs) were prepared via a hydrothermal method and then modified by polyethylene glycol (PEG). The modified P-CSHs combined with an internal recycle reactor could successfully recover the phosphorus from electroplating wastewater. The modified P-CSHs were characterized by X-ray diffraction (XRD), N2 adsorption-desorption isotherms, and Fourier transform infrared spectroscopy (FT-IR). After compared with different samples, the modified P-CSHs-PEG2000 sample had larger specific surface area of 87.48 m2/g and higher pore volume of 0.33 cm3/g, indicating a high capacity for phosphorus recovery. In the process of phosphorus recovery, the pH value of solution was increased to 9.5, which would enhance the recovery efficiency of phosphorus. The dissolution rate of Ca2+ from P-CSH-PEG2000 was fast, which was favorable for phosphorus precipitation and phosphorus recovery. The effects of initial concentration of phosphorus, P-CSHs-PEG2000 dosage, and stirring speed on phosphorus recovery were analyzed, so the optimal operation conditions for phosphorus recovery were obtained. The deposition was analyzed by XRD, N2 adsorption-desorption, and SEM techniques; it was indicated that the pore volume and surface area of the P-CSHs-PEG2000 were significantly reduced, and the deposition on the surface of P-CSHs-PEG2000 was hydroxyapatite.

scholarly journals Chemical Composition and Porosity Characteristics of Various Calcium Silicate-Based Endodontic Cements

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Seok Woo Chang
Keyword(s):  
Chemical Composition ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Calcium Silicate ◽  
Pore Diameter ◽  
Clinical Performance ◽  
Powder Analysis ◽  
Adsorption Desorption

Chemical composition and porosity characteristics of calcium silicate-based endodontic cements are important determinants of their clinical performance. Therefore, the aim of this study was to investigate the chemical composition and porosity characteristics of various calcium silicate-based endodontic cements: MTA-angelus, Bioaggregate, Biodentine, Micromega MTA, Ortho MTA, and ProRoot MTA. The specific surface area, pore volume, and pore diameter were measured by the porosimetry analysis of N2 adsorption/desorption isotherms. Chemical composition and powder analysis by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were also carried out on these endodontic cements. Biodentine and MTA-angelus showed the smallest pore volume and pore diameter, respectively. Specific surface area was the largest in MTA-angelus. SEM and EDS analysis showed that Bioaggregate and Biodentine contained homogenous, round and small particles, which did not contain bismuth oxide.

scholarly journals Phenol adsorption on high microporous activated carbons prepared from oily sludge: equilibrium, kinetic and thermodynamic studies

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
N. Mojoudi ◽  
N. Mirghaffari ◽  
M. Soleimani ◽  
H. Shariatmadari ◽  
C. Belver ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Pore Volume ◽  
Activated Carbons ◽  
Ph Value ◽  
Chemical Activation ◽  
Bet Surface Area ◽  
Polluted Water ◽  
Oily Sludge ◽  
Maximum Adsorption Capacity ◽  
Adsorption Desorption

AbstractThe purpose of this study was the preparation, characterization and application of high-performance activated carbons (ACs) derived from oily sludge through chemical activation by KOH. The produced ACs were characterized using iodine number, N2 adsorption-desorption, Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The activated carbon prepared under optimum conditions showed a predominantly microporous structure with a BET surface area of 2263 m2 g−1, a total pore volume of 1.37 cm3 g−1 and a micro pore volume of 1.004 cm3 g−1. The kinetics and equilibrium adsorption data of phenol fitted well to the pseudo second order model (R2 = 0.99) and Freundlich isotherm (R2 = 0.99), respectively. The maximum adsorption capacity based on the Langmuir model (434 mg g−1) with a relatively fast adsorption rate (equilibrium time of 30 min) was achieved under an optimum pH value of 6.0. Thermodynamic parameters were negative and showed that adsorption of phenol onto the activated carbon was feasible, spontaneous and exothermic. Desorption of phenol from the adsorbent using 0.1 M NaOH was about 87.8% in the first adsorption/desorption cycle and did not decrease significantly after three cycles. Overall, the synthesized activated carbon from oily sludge could be a promising adsorbent for the removal of phenol from polluted water.

scholarly journals Rhodium catalysts build into the structure of a silicate support in the hydroformylation of alkenes

2013 ◽  
Vol 11 (4) ◽  
pp. 561-568 ◽  
Author(s):  
Thomas Borrmann ◽  
Andrew McFarlane ◽  
Uwe Ritter ◽  
James Johnston
Keyword(s):  
Surface Area ◽  
Heterogeneous Catalyst ◽  
Pore Volume ◽  
Calcium Silicate ◽  
Rhodium Catalysts ◽  
Product Phase ◽  
Silicate Structure ◽  
Acid Washing ◽  
Catalytic Material ◽  
Low Alcohol

AbstractRhodium is build into a nano-structured calcium silicate during the synthesis of the silicate. Thereby, it was desired to create a robust heterogeneous catalyst, which does not suffer from catalyst leaching like rhodium impregnated on a pre-formed silicate. While this was achieved, the silicate structure was adversely affected by the incorporation of rhodium — the surface area and pore volume of the material were found to be comparatively low. Alcohol and acid washing were tested to address this issue. The alcohol treatment proved detrimental as catalytic material was leached from the silicate. The acid washed rhodium containing calcium silicate was quite active in the hydroformylation of alkenes and did not suffer loss of catalyst into the product phase. Acid treated rhodium containing silicates were more active than their untreated counterparts but less selective due to access to the rhodium centers being opened.

scholarly journals The Synthesis and Characterisation of Nano-Structured Calcium Silicate

2021 ◽  
Author(s):  
◽  
Andrew James McFarlane
Keyword(s):  
Surface Tension ◽  
Surface Area ◽  
Pore Volume ◽  
Calcium Silicate ◽  
Continuous Process ◽  
Substantial Reduction ◽  
Geothermal Water ◽  
Atomic Scale ◽  
Open Framework ◽  
Macro Scale

<p>Nano-structured calcium silicate consists of randomly stacked nano-sized platelets that make up an open framework structure of macropores that resembles a house of cards. This structure affords the material the desirable physical properties of a large pore volume and a highly accessible surface area that exceed many other silicas and silicates. The material is possibly related to other disordered calcium silicate hydrates at an atomic level, although it is the macro-structure and the potential of performing chemistry upon its surface that is of great interest. Due to the novelty of nano-structured calcium silicate, little was known about it before this work. The focus of this study has therefore been placed upon characterising the material and determining the conditions that allow the pore volume and surface area to be maximised. The material is prepared through an initial precipitation from the reaction of a calcium salt with monomeric silica, followed subsequently by self-ordering on both an atomic-scale and on a macro-scale to develop the porous framework. The framework of the material has been found to collapse due to forces created from surface tension during the removal of water from the pores upon drying. The result of this collapse is a substantial reduction in both the surface area and pore volume of the material. Three different methods have been developed to maintain the structure with each modification producing a material that is suitable for different applications. A reinforcing process following the development of the open framework whereby additional silica is polymerised upon the structure strengthens the material so that the forces resulting from the removal pore water are unable to cause collapse of the framework. This material is therefore able to be repeatedly re-wet and dried without any detrimental effect to the pore volume or surface area of the material. The replacement of water within the pores with 2-ethoxyethanol, that has a low surface tension, and by modifying the material through treatment with acid have also been found to prevent collapse of the structure. Through the knowledge gained of the development of the nano-structured calcium silicate and of the reaction conditions required for the optimisation of the surface area and pore volume, a semi-continuous process has been devised that has allowed for production of the material on a larger scale. This work also contains details on the formation of nano-structured calcium silicate by using geothermal water from an electricity generation plant as the source of monomeric silica rather than using sodium silicate. Currently, the formation of a scale from supersaturated geothermal water is problematic for the industries that use the fluid and limits the use of the resource. The removal of monomeric silica from geothermal water as a result of producing nanostructured calcium silicate prevents the formation of the scale and therefore allows a greater proportion of the thermal energy in the fluid to be potentially utilised.</p>

Application of Foam Separation Technology to Tea Saponin Extraction

2014 ◽  
Vol 997 ◽  
pp. 173-177 ◽  
Author(s):  
Yu Qiong Wu
Keyword(s):  
Ph Value ◽  
Optimal Operation ◽  
Enrichment Ratio ◽  
Liquid Volume ◽  
Single Factor ◽  
Separation Technology ◽  
Foam Separation ◽  
Tea Saponin ◽  
Operation Conditions ◽  
Single Factor Experiment

In this paper, a purity of 52.58% crude tea saponin as the research object, through the foam separation technology, tea saponin extraction process was researched. The feed concentration, gas flow rate, liquid volume and pH value were studied through single factor experiment, the rate of recovery and enrichment ratio as evaluation indexes, the single factor experiment results are analyzed, The design of L9 (34) orthogonal test was applied to confirm the optimum condition: the initial feed solution concentration 0.3mg/ml, air velocity 100ml/min, pH value of 6.5, liquid volume 35ml, enrichment ratio of 3.7896, the recovery rate 82.06%. The purity of the product reached 89.48% under the optimal operation conditions. The results showed that the foam separation techniques is applicable to tea saponin extraction.

CuO/CeO2 and CuO/PrO2-CeO2 Catalysts for Preferential Oxidation of CO

2013 ◽  
Vol 773 ◽  
pp. 601-605 ◽  
Author(s):  
Zhi Jun Zhao ◽  
Ruo Yu Wang ◽  
Qian Long Zhao ◽  
En Peng Wang ◽  
Hai Quan Su ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Hydrothermal Method ◽  
Surface Area ◽  
Pore Volume ◽  
Crucial Role ◽  
Textural Properties ◽  
Bet Surface Area ◽  
Oxidation Of Co ◽  
Preferential Oxidation Of Co ◽  
Adsorption Desorption

The CuO/CeO2and CuO/PrO2-CeO2catalysts were prepared by the hydrothermal method, and characterized via XRD, SEM and N2adsorption-desorption techniques. The study shows that the BET surface area and pore volume of the CuO/PrO2-CeO2catalysts increase with the increase of praseodymium content. The CuO/CeO2catalyst presents higher catalytic activity in compare with the CuO/PrO2-CeO2catalysts although the addition of praseodymium promotes textural properties of the CuO/CeO2catalysts, and it proves that the interaction of CuO and CeO2has a crucial role in CO-PROX.

The Preparation and Characterization of the Mesoporous Poly(bisphenol-A carbonate) – Silica Nanocomposites

2014 ◽  
Vol 513-517 ◽  
pp. 82-85
Author(s):  
Rui Rui Li ◽  
Yue Shi ◽  
Lei Zu ◽  
Hui Qin Lian ◽  
Yang Liu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Pore Diameter ◽  
Ph Value ◽  
Sol Gel ◽  
Synthesis System ◽  
Silica Nanocomposites

The mesoporous polycarbonate-silica nanocomposite materials were synthesized through the modified sol-gel approach under acidic condition. The specific surface area, pore diameter and pore volume of polycarbonate-silica could be controlled by changing the acidity of the synthesis system. The polycarbonate-silica possess an irregular block morphology according to the scanning electron microscopy observations. With decreasing the pH value of the synthesis system, the specific surface area and pore diameter of polycarbonate-silica were raised but the pore volume was reduced. The maximum specific surface area of polycarbonate-silica was 701.71m2/g which presented by the results of Nitrogen adsorptiondesorption isotherms.

scholarly journals Synthesis of micro-mesopores flowerlike γ-Al2O3 nano-architectures

2014 ◽  
Vol 79 (8) ◽  
pp. 1007-1017 ◽  
Author(s):  
Mozaffar Abdollahifar ◽  
Reza Zamani ◽  
Ehsan Beiygie ◽  
Hosain Nekouei
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Total Pore Volume ◽  
High Specific Surface Area ◽  
X Ray Diffraction ◽  
N2 Adsorption ◽  
X Ray ◽  
Adsorption Desorption

The micro-mesopores flowerlike ?-Al2O3 nano-architectures have been synthesized by thermal decomposition method using the synthesized AlOOH (boehmite) as precursor. After calcination at 500?C for 5 h, the obtained flowerlike ?-Al2O3 has similar structure like the AlOOH precursor. X-ray diffraction (XRD), FTIR, TG, FESEM and TEM techniques were used to characterize morphology and structure of the synthesized samples. The specific surface area (BET), pore volume and pore-size distribution of the products were determined by N2 adsorption-desorption measurements. The flowerlike ?-Al2O3 showed BET high specific surface area 148 m2 g-1 with total pore volume 0.59 cm3 g-1.

Experimental investigation of nitric oxide removal from flue gas using hexamminecobalt(II) solution scrubbing in a pilot-scale facility

2018 ◽  
Vol 36 (6) ◽  
pp. 505-512 ◽  
Author(s):  
Bing Han ◽  
Qinghai Li ◽  
Zhen Liu ◽  
Zhongchao Tan ◽  
Yanguo Zhang
Keyword(s):  
Nitric Oxide ◽  
Experimental Investigation ◽  
Removal Efficiency ◽  
Reaction Temperature ◽  
Ph Value ◽  
Pilot Scale ◽  
Optimal Operation ◽  
Experimental Results ◽  
No Removal ◽  
Operation Conditions

An experimental investigation of operational parameters, including liquid/gas ratio (L/G), inlet nitric oxide (NO) concentration, reaction temperature, and pH value of absorbing agent, on NO removal efficiency with hexamminecobalt(II) solution scrubbing was conducted on a pilot-scale facility to search optimal operation conditions. The experimental results show that NO removal efficiency increased with the pH value of hexamminecobalt solution, while the improving rate dropped gradually. When the reaction temperature increased, the NO removal efficiency increased first and then decreased. At the same time, NO removal efficiency increased with the increasing of L/G and hexamminecobalt concentration, while the removal efficiency did not change much at low NO concentration. The pH of 10.4 and L/G of 16 L/m3 were close to the optimal operation conditions, and the scrubbing temperature fell within a reasonable operation temperature. The experimental results can be used as a reference for the design and operation of scaled-up industrial devices.

The Effect of Aging Temperature and pH Value of Aging Solution on the Microstructure of ZrO2-SiO2 Aerogels

2016 ◽  
Vol 697 ◽  
pp. 368-371 ◽  
Author(s):  
Ying Chen Qiao ◽  
Xiao Lei Li ◽  
Jian He ◽  
Hui Ming Ji ◽  
Zhu Rui Shen ◽  
...  
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Alkaline Solution ◽  
Aging Temperature ◽  
Pore Volume ◽  
Ph Value ◽  
Solution Ph

ZrO2-SiO2 gels were prepared by prehydrolysis method with sol-gel process. Then,the wet gels were aged at different temperatures (60,110,170 °C) in ethanol or alkaline solution (pH=8). Finally, the monolithic ZrO2-SiO2 aerogels were obtained by supercritical fluid drying. N2 adsorption-desorption, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) were used to characterize the microstructure of aerogels. The aim of this research is to study the effect of aging temperature and pH value of aging solution on the microstructure of ZrO2-SiO2 aerogels. The results show that the specific surface area and pore volume of ZrO2-SiO2 aerogels aging in alkaline solution (pH=8) is lower than that of aging in the ethanol. And there is a shift of the pore size distribution towards larger values. This is because the cross-linking reaction in alkaline solution enlarges the particle size. As the aging temperature increases, the specific surface area and pore volume decrease and the particle size distribution of ZrO2-SiO2 aerogels is more uniform.

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