scholarly journals Behavior of activated carbons by compound modification in high gravity for toluene adsorption

2017 ◽  
Vol 36 (3-4) ◽  
pp. 1018-1030
Author(s):  
Qiang Guo ◽  
You-Zhi Liu ◽  
Gui-Sheng Qi ◽  
Wei-Zhou Jiao
Keyword(s):  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Functional Groups ◽  
Specific Surface Area ◽  
Activated Carbons ◽  
Packed Bed ◽  
High Gravity ◽  
Rotating Packed Bed ◽  
Compound Modification

The rotating packed bed is a chemical apparatus that strengthens mass transfer between phases to enhance their reactivity. It can be used to modify adsorbent materials, greatly improving their chemical properties. This article studies the effect of compound modification of activated carbons in a high-gravity environment on their toluene adsorption. The compound modification includes physical (N2) and chemical modification (HNO3), and the effect of modification is compared between traditional fixed-bed and rotating packed bed modification. The physical characteristics of the activated carbons, including pore size, specific surface area, and morphology are tested by Brunauer–Emmett–Teller and scanning electron microscopy, and the surface functional groups of the activated carbons are determined by Fourier transform infrared spectroscopy and Boehm titration. The results indicate that the activated carbons modified by rotating packed bed have a larger specific surface area (871.5 m2/g) and smaller pore size (0.524 nm), and the content of acidic oxygen-containing groups is 1.5 times that of unmodified activated carbons. The adsorption capacity of the activated carbons compound-modified by rotating packed bed increases by 69% compared with the unmodified activated carbons. The adsorption by the rotating packed bed-compound-modified activated carbons obeys the Freundlich model. The modification of activated carbons by rotating packed bed greatly enhances their specific surface area, pore size, and surface content of oxygen-containing functional groups, markedly improving the adsorption performance and increasing the utilization rate.

Performance of anaerobic packed-bed system with different media characteristics

1996 ◽  
Vol 34 (5-6) ◽  
pp. 453-459 ◽  
Author(s):  
Joo-Hwa Tay ◽  
S. Jeyaseelan ◽  
Kuan-Yeow Show
Keyword(s):  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Removal Efficiency ◽  
Specific Surface Area ◽  
Oxygen Demand ◽  
Specific Area ◽  
Packed Bed ◽  
Cod Removal ◽  
Cod Removal Efficiency

The effects of media specific surface area, porosity, and pore size on the performance of upflow anaerobic packed-bed reactors (APBRs) were examined in the laboratory. The results showed that, the APBR containing media of the lowest surface area but the largest pore size and porosity, demonstrated the highest chemical oxygen demand (COD) removal efficiencies of 90% and 73% at loading rates of 8 and 16 g COD/L.day, respectively. An increase of over 40% in specific area in an APBR had not improved the removal efficiency, instead it produced 16% lower in COD removal efficiency at loading rate of 16 g COD/L.d. A study on the effects of effluent recycle indicates that the APBR having the largest pore size and porosity benefited from the recirculation. The reactor exhibited an increase in overall COD removal efficiency of 8% and a substantial decrease in effluent COD concentration of 30%. The results suggest that media pore size and porosity play a more significant role than media specific surface area in the performance of upflow APBRs.

scholarly journals Development and Characterization of Composite Carbon Adsorbents with Photocatalytic Regeneration Ability: Application to Diclofenac Removal from Water

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 173
Author(s):  
Velma Beri Kimbi Yaah ◽  
Satu Ojala ◽  
Hamza Khallok ◽  
Tiina Laitinen ◽  
Marcin Selent ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Functional Groups ◽  
Specific Surface Area ◽  
Palm Kernel ◽  
Hydrothermal Carbonization ◽  
Carbon Composite ◽  
Carbon Adsorbents ◽  
Regeneration Ability ◽  
Activation Temperature

This paper presents results related to the development of a carbon composite intended for water purification. The aim was to develop an adsorbent that could be regenerated using light leading to complete degradation of pollutants and avoiding the secondary pollution caused by regeneration. The composites were prepared by hydrothermal carbonization of palm kernel shells, TiO2, and W followed by activation at 400 °C under N2 flow. To evaluate the regeneration using light, photocatalytic experiments were carried out under UV-A, UV-B, and visible lights. The materials were thoroughly characterized, and their performance was evaluated for diclofenac removal. A maximum of 74% removal was observed with the composite containing TiO2, carbon, and W (HCP25W) under UV-B irradiation and non-adjusted pH (~5). Almost similar results were observed for the material that did not contain tungsten. The best results using visible light were achieved with HCP25W providing 24% removal of diclofenac, demonstrating the effect of W in the composite. Both the composites had significant amounts of oxygen-containing functional groups. The specific surface area of HCP25W was about 3 m2g−1, while for HCP25, it was 160 m2g−1. Increasing the specific surface area using a higher activation temperature (600 °C) adversely affected diclofenac removal due to the loss of the surface functional groups. Regeneration of the composite under UV-B light led to a complete recovery of the adsorption capacity. These results show that TiO2- and W-containing carbon composites are interesting materials for water treatment and they could be regenerated using photocatalysis.

The relationship between geotechnical index properties and the pore-size distribution of compacted clayey silts

2015 ◽  
Vol 22 (6) ◽  
Author(s):  
Nazile Ural
Keyword(s):  
Specific Surface ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Correlation Coefficients ◽  
Liquid Limit ◽  
Index Properties

AbstractIn this study, the relationships between geotechnical index properties and the pore-size distribution of compacted natural silt and artificial soil mixtures, namely, silt with two different clays and three different clay percentages (10%, 20%, and 40%), were examined and compared. Atterberg’s limit tests, standard compaction tests, mercury intrusion porosimetry, X-ray diffraction, scanning electron microscopy (SEM) analysis, and Brunauer-Emmett-Teller specific surface analysis were conducted. The results show that the liquid limit, the cumulative pore volume, and specific surface area of artificially mixed soils increase with an increase in the percentage of clay. The cumulative pore volume and specific surface area with geotechnical index properties were compared. High correlation coefficients were observed between the specific areas and both the liquid limit and the plasticity index, as well as between the cumulative pore volume and both the clay percentage and the

Mesoporous Activated Carbon Filaments

1996 ◽  
Vol 454 ◽  
Author(s):  
Weiming Lu ◽  
D. D. L. Chung
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mesoporous Activated Carbon ◽  
Carbon Filaments

ABSTRACTActivated carbon filaments of diameter ∼0.1 μm, main pore size (BJH) 55 Å, specific surface area 1310 m2/g and yield 36.2% were obtained by activating carbon filaments of diameter ∼ 0.1 urn in C02 + N2 (1:1) at 970°C for 80 min. Prior to this activation, the filaments were surface oxidized by exposure to ozone.

High specific surface area ordered mesoporous silica COK-12 with tailored pore size

2019 ◽  
Vol 280 ◽  
pp. 133-143 ◽  
Author(s):  
Laura M. Henning ◽  
Diego Díaz Cubas ◽  
Maria G. Colmenares ◽  
Johannes Schmidt ◽  
Maged F. Bekheet ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Ordered Mesoporous Silica ◽  
Ordered Mesoporous

scholarly journals Adsorption of pharmaceuticals from aqueous solutions using biochar derived from cotton gin waste and guayule bagasse

Biochar ◽  
2020 ◽  
Author(s):  
Marlene C. Ndoun ◽  
Herschel A. Elliott ◽  
Heather E. Preisendanz ◽  
Clinton F. Williams ◽  
Allan Knopf ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Functional Groups ◽  
Specific Surface Area ◽  
High Surface ◽  
Strong Interactions ◽  
Solution Ph ◽  
Experimental Conditions ◽  
Cotton Gin Waste ◽  
Cotton Gin

Abstract Biochars produced from cotton gin waste (CG) and guayule bagasse (GB) were characterized and explored as potential adsorbents for the removal of pharmaceuticals (sulfapyridine-SPY, docusate-DCT and erythromycin-ETM) from aqueous solution. An increase in biochar pyrolysis temperature from 350 οC to 700 οC led to an increase in pH, specific surface area, and surface hydrophobicity. The electronegative surface of all tested biochars indicated that non-Coulombic mechanisms were involved in adsorption of the anionic or uncharged pharmaceuticals under experimental conditions. The adsorption capacities of Sulfapyridine (SPY), Docusate (DCT) and Erythromycin (ETM) on biochar were influenced by the contact time and solution pH, as well as biochar specific surface area and functional groups. Adsorption of these pharmaceutical compounds was dominated by a complex interplay of three mechanisms: hydrophobic partitioning, hydrogen bonding and π–π electron donor–acceptor (EDA) interactions. Despite weaker π–π EDA interactions, reduced hydrophobicity of SPY− and increased electrostatic repulsion between anionic SPY− and the electronegative CG biochar surface at higher pH, the adsorption of SPY unexpectedly increased from 40% to 70% with an increase in pH from 7 to 10. Under alkaline conditions, adsorption was dominated by the formation of strong negative charge-assisted H-bonding between the sulfonamide moiety of SPY and surface carboxylic groups. There seemed to be no appreciable and consistent differences in the extent of DCT and ETM adsorption as the pH changed. Results suggest the CG and GB biochars could act as effective adsorbents for the removal of pharmaceuticals from reclaimed water prior to irrigation. High surface area biochars with physico-chemical properties (e.g., presence of functional groups, high cation and anion exchange capacities) conducive to strong interactions with polar-nonpolar functionality of pharmaceuticals could be used to achieve significant contaminant removal from water. Graphic Abstract

scholarly journals Activated Carbons from Thermoplastic Precursors and Their Energy Storage Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 896 ◽  
Author(s):  
Hye-Min Lee ◽  
Kwan-Woo Kim ◽  
Young-Kwon Park ◽  
Kay-Hyeok An ◽  
Soo-Jin Park ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Specific Surface ◽  
Surface Area ◽  
Field Emission ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Cross Linking ◽  
Mesopore Volume

In this study, low-density polyethylene (LDPE)-derived activated carbons (PE-AC) were prepared as electrode materials for an electric double-layer capacitor (EDLC) by techniques of cross-linking, carbonization, and subsequent activation under various conditions. The surface morphologies and structural characteristics of the PE-AC were observed by field-emission scanning electron microscope, Cs-corrected field-emission transmission electron microscope, and X-ray diffraction analysis, respectively. The nitrogen adsorption isotherm-desorption characteristics were confirmed by Brunauer–Emmett–Teller, nonlocal density functional theory, and Barrett–Joyner–Halenda equations at 77 K. The results showed that the specific surface area and total pore volume of the activated samples increased with increasing the activation time. The specific surface area, the total pore volume, and mesopore volume of the PE-AC were found to be increased finally to 1600 m2/g, 0.86 cm3/g, and 0.3 cm3/g, respectively. The PE-AC also exhibited a high mesopore volume ratio of 35%. This mesopore-rich characteristic of the activated carbon from the LDPE is considered to be originated from the cross-linking density and crystallinity of precursor polymer. The high specific surface area and mesopore volume of the PE-AC led to their excellent performance as EDLC electrodes, including a specific capacitance of 112 F/g.

scholarly journals Effects of Wet Oxidation Process on Biochar Surface in Acid and Alkaline Soil Environments

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2362 ◽  
Author(s):  
Qinya Fan ◽  
Liqiang Cui ◽  
Guixiang Quan ◽  
Sanfei Wang ◽  
Jianxiong Sun ◽  
...  
Keyword(s):  
Specific Surface ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Functional Groups ◽  
Specific Surface Area ◽  
Contaminated Soils ◽  
Soil Conditions ◽  
Acid Oxidation ◽  
Wet Oxidation ◽  
Alkaline Soil

Biochar has been studied for remediation of heavy metal-contaminated soils by many researchers. When in external conditions, biochar in soils ages, which can transform its structural properties and adsorption capacity. This study was conducted with two oxidation processes, HNO3/H2SO4 and NaOH/H2O2, to simulate the effects of biochar in acid and alkaline soil conditions. The results show that the oxygen-containing functional groups increased in aged biochar, which led to improve the ratio of oxygen and carbon (O/C). Nitro functional groups were found in the acid-oxidation treated biochar. Destroyed ditches and scars were observed on the surface of aged biochar and resulted in growth in their specific surface area and porosity. Specific surface area increased by 21.1%, 164.9%, and 63.0% for reed-derived biochar treated with water washing, acid oxidation, and basic oxidation, respectively. Greater peaks in the Fourier Transform Infrared Spectroscopy (FTIR) results were found in C–O and O–H on the surface of field-aged biochar. Meanwhile, mappings of energy-dispersive spectroscopy showed that biochar aged in soil was abundant in minerals such as silicon, iron, aluminum, and magnesium. In summary, biochar subjected to wet oxidation aging had an increased capacity to immobilize Cd compared to unaged biochar, and the adsorption capacity of oxidized biochar increased by 28.4% and 13.15% compared to unaged biochar due to improvements in porosity and an increase in functional groups.

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