Characterization of Physical Adsorption Systems. III. The Separate Effects of Pore Size and Surface Acidity upon the Adsorbent Capacities of Activated Carbons

Graham, Donald

doi:10.1021/j150531a022

Cited by 134 publications

(58 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Many discussions in this respect have been generated, and the agreed pore diameter for MB adsorption averages 1.3 nm. 29,30 Thus, it would be interesting that small deviations from the mathematical equations used could also be considered in the pore size determination.…”

Section: Adsorption Isothermsmentioning

confidence: 99%

Thermogravimetric and spectroscopic study (TG–DTA/FT–IR) of activated carbon from the renewable biomass source Babassu

Oliveira¹,

Andrade²,

Trindade³

et al. 2016

Quim. Nova

View full text Add to dashboard Cite

carbons (ACs) with well-developed microstructure and high microporosity were obtained from biomass by potassium hydroxide activation. The preparation process consisted in producing carbon materials in the ratios of activating agent to raw material 70:30, 50:50, 30:70 and 25:75 (w/w) characterized by thermal analysis coupled to spectroscopy (TG-DTA / FT-IR), scanning electron microscopy (SEM), N 2 adsorption isotherms at -196 °C and activation isotherm at 500 and 600 °C for 3.0 h. Specific surface areas (SBET) within 728 and 1712 m 2 g -1 and (S mic ) within 1054 and 1923 m 2 g -1 were obtained, while the micropores surface area was calculated using the Dubinin-Astakhov (DA) equation and the pore size distribution calculated from density functional theory (DFT) was found to be in the range 1.09 -1.77 nm. Adsorption isotherms were fitted using Langmuir and Freundlich non-linear models and the adsorption capacity determined for methylene blue dye was between 27.13 and 459.20 mg g -1 .

show abstract

Section: Adsorption Isothermsmentioning

confidence: 99%

Thermogravimetric and spectroscopic study (TG–DTA/FT–IR) of activated carbon from the renewable biomass source Babassu

Oliveira¹,

Andrade²,

Trindade³

et al. 2016

Quim. Nova

View full text Add to dashboard Cite

show abstract

“…These aromatic compounds are then decomposed completely via the photo-Kolbe reaction to CO 2 , NH 4 + , NO 3 À and SO 4 2À ions, which leave the pores and make way for the degradation of new MB molecules. Considering the similar sizes of the two largest molecules in this process, MB (0.72 nm) and the sulfoxide (0.76 nm), as calculated from the corresponding cross-sectional areas, 14 any pore size confinement will most likely affect the transport of MB itself to its adsorption site inside the pore, impeding the continuous supply of the reactant. The diffusion of liquids in pores has been studied by Ternan, who observed that even pores as large as 40 nm can impose serious diffusion limitations on molecules as small as 2 nm.…”

mentioning

confidence: 99%

Enhanced photocatalytic properties in well-ordered mesoporous WO3

Krissanasaeranee

Pattinson

et al. 2010

Chem. Commun.

View full text Add to dashboard Cite

We used polyisoprene-block-ethyleneoxide copolymers as structure-directing agents to synthesise well-ordered and highly-crystalline mesoporous WO 3 architectures that possess improved photocatalytic properties due to enhanced dye-adsorption in absence of diffusion limitation.As a green technology, semiconductor photocatalysis has attracted increasing interest driven by the search for new energy sources during the past few decades.1 The performance of the photocatalysts strongly depends on their crystal structure and morphology.1,2 It is widely recognized that high crystallinity and a continuous network architecture with controlled pore sizes that facilitate molecular access to high surface areas are highly desired for maximizing their photocatalytic performance. 3,4 This has recently stimulated intensive research in designing mesoporous metal oxides, such as TiO 2 , Nb 2 O 5 , and ZrO 2 . 5 The major drawback of these attempts is that the oxide structures often contain a significant amount of undesired amorphous content, which facilitates the recombination of electrons and holes, thereby limiting the catalytic efficiency.2 The crystallinity can be improved by annealing at high temperatures, upon which, however, the ordered structure typically collapses. Hence, synthesising well-ordered mesoporous structures with high crystallinity still remains a major challenge. 6 Recently, we used polyisoprene-block-ethyleneoxide (PI-b-PEO) copolymers as structure-directing agents to synthesise TiO 2 with controlled mesoporous structures. 7,8 The large interaction parameter between the PI and PEO blocks and the high degree of polymerization allows the rapid formation of structures with long-range order. In addition, the PI-b-PEO morphology has relatively large pore sizes, which facilitate the effective infiltration of functional materials. The resulting TiO 2 exhibited excellent performance in dye-sensitized solar cells. Although TiO 2 is currently the most studied semiconductor photocatalyst, its wide band gap (3.2 eV) limits TiO 2 to a small ultraviolet fraction of solar energy. 9 In contrast, tungsten trioxide (WO 3 ) has a narrower band gap (2.4-2.8 eV) that enables harvesting visible light.10 Only a few studies have so far been devoted to the synthesis of porous WO 3 , i.e. using PMMA spheres 11 and by anodization of tungsten foil. 12 Despite yielding only macroporous and weakly-ordered structures these studies still demonstrated enhanced photocatalytic properties compared with their dense counterparts. It is therefore likely that improving the pore structure and crystallinity will maximise the photocatalytic performance of WO 3 . Herein, we demonstrate the synthesis of highly-crystalline mesoporous WO 3 with well-ordered pore architectures using a sol-gel process and PI-b-PEO copolymers as structure-directing agents. We investigated the effect of polymer-to-WO 3 weight ratio on the morphology and tested the photocatalytic performance for the degradation of methylene blue under visible light.In a typical synthesis, 45 mg ...

show abstract

“…where SMB is the specific surface area in m 2 /g; qmax is the maximum adsorption capacity in mg/g (calculated from the Langmuir isotherm); aMB is the occupied surface area of one molecule of methylene blue = 197.2 Å 2 [25]. N is the Avogadro's number, 6.02 × 10 23 ; and M is the molecular weight of methylene blue, 373.9 g/mol.…”

Section: Adsorption Testsmentioning

confidence: 99%

Comparative Sorption of Methylene Blue onto Hydrophobic Clays

Sponza

Fernández

Yang³

et al. 2015

Environments

View full text Add to dashboard Cite

Chemical modifications of clay to remove methylene blue (MB) from aqueous solutions at room temperature were compared. Natural bentonite (NC) was modified by cation exchange with hexadecyltrimethylammonium chloride (HC), bencyltriethylammonium chloride (BC), and tetramethylammonium chloride (TC) to reverse the surface polarity of the hydrophilic bentonite. The adsorption of MB was studied and fitted by the adsorption theories of Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin. Equilibrium parameters were calculated, indicating that chemical modification did not improve the adsorption, due to the electrostatic adsorption mechanism. Specific surface area was determined, reporting the following trend: NC > TC > BC > HC. Isotherms show that TC is the best modified clay for the adsorption of MB with a capacity of 217 mg/g. Adsorbents were characterized by SEM and the determination of their point zero charge, indicating a charge reversal at pH 9.5 and a heterogeneous surface that is optimum for the adsorption of molecules and ions onto their surfaces.

show abstract

Characterization of Physical Adsorption Systems. III. The Separate Effects of Pore Size and Surface Acidity upon the Adsorbent Capacities of Activated Carbons

Cited by 134 publications

References 5 publications

Thermogravimetric and spectroscopic study (TG–DTA/FT–IR) of activated carbon from the renewable biomass source Babassu

Thermogravimetric and spectroscopic study (TG–DTA/FT–IR) of activated carbon from the renewable biomass source Babassu

Enhanced photocatalytic properties in well-ordered mesoporous WO3

Comparative Sorption of Methylene Blue onto Hydrophobic Clays

Contact Info

Product

Resources

About