Steam activation and mild air oxidation of vacuum pyrolysis biochar

Bardestani, Raoof; Kaliaguine, Serge

doi:10.1016/j.biombioe.2017.10.011

Cited by 102 publications

(44 citation statements)

References 53 publications

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“…According to Equation , a plot of x / W (1− x )— y versus x gives a straight line with an intercept at

β_{0} = \frac{1}{C \times W_{ml}}

and a slope of β 1 = ( C − 1)/( C × W ml ) . For a mildly air oxidized biochar, for example, the slope equals 53 g −1 and the intercept is 0.48 g −1 (Figure ) . The mass of gas that forms a monolayer, W ml , is obtained from the sum of the intercept and slope:

\frac{1}{W_{ml}} = β_{0} + β_{1}

…”

Section: Theorymentioning

confidence: 99%

“…The purpose of modifying the surface was to adsorb carbamazepine and bisphenol from industrial wastewater. Bardestani and Kaliaguine instead applied steam activation to increase biochar surface area, which could be easily implemented in line with the pyrolysis process (post‐pyrolysis treatment). They used a pyrolysis biochar obtained from a mixture of spruce, fir, and pine shredded wood pyrolyzed at 475°C, and increased SSA of the sample from 50 m 2 ⋅ g −1 to 1025 m 2 ⋅ g −1 , by steam activation at 900°C for 1 hour.…”

Section: Applicationsmentioning

confidence: 99%

“…[3] For a mildly air oxidized biochar, for example, the slope equals 53 g −1 and the intercept is 0.48 g −1 (Figure 4). [24] The mass of gas that forms a monolayer, W ml , is obtained from the sum of the intercept and slope:…”

Section: Theorymentioning

confidence: 99%

“…Relative pressure (P/P 0 ) F I G U R E 3 Types of hysteresis loops obtained by nitrogen physisorption [15] F I G U R E 4 Example of BET plot to derive β 0 and β 1 (Equations (1) and (4)) [24] SSA =…”

Section: H3 H4mentioning

confidence: 99%

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Experimental methods in chemical engineering: specific surface area and pore size distribution measurements—BET, BJH, and DFT

2019

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Gas physisorption is an experimental technique based on equilibrium Van der Waals interactions between gas molecules and solid particles, that quantifies the specific surface area (SSA), pore size distribution (PSD), and pore volume of solids and powders. The performance of catalysts, absorbents, chromatography column materials, and polymer resins depends on these morphological properties. Here we introduce the basic principles and procedures of physical adsorption, especially nitrogen physisorption, as a guide to students and researchers unfamiliar with the field. The Brunauer‐Emmett‐Teller theory (BET) is a common approach to estimate SSA that extends the Langmuir monolayer molecular adsorption model to multilayer layers. It relies on an equilibrium adsorption isotherm, measured at the normal boiling point of the adsorbate, eg, 77 K or 87 K for N2 and Ar, respectively. Web of Science indexed 45 400 articles in 2016 and 2017 that mentioned N2 adsorption porosimetry—BET and BJH (Barrett‐Joyner‐Halenda) keywords. The VOSViewer bibliometric tool grouped these articles into four research clusters: adsorption, activated carbon in aqueous solutions for removal of heavy metal ions; synthesis of nanoparticles and composites; catalysts performance in oxidation and reduction processes; and photocatalytic degradation with TiO2. According to the literature, the accuracy of the density function theory (DFT) method is higher than with the BJH theory and it is more reliable.

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“…According to Equation , a plot of x / W (1− x )— y versus x gives a straight line with an intercept at

β_{0} = \frac{1}{C \times W_{ml}}

\frac{1}{W_{ml}} = β_{0} + β_{1}

…”

Section: Theorymentioning

confidence: 99%

Section: Applicationsmentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: H3 H4mentioning

confidence: 99%

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Experimental methods in chemical engineering: specific surface area and pore size distribution measurements—BET, BJH, and DFT

2019

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“…Prior to either the physical or chemical activation process, the carbon precursor needs to be carbonized to produce char. If the formed char is activated using carbon dioxide or steam as the activating agent, the process is called physical activation [6]. If the char is activated in the presence of chemical agents, the process is termed chemical activation [7].…”

Section: Introductionmentioning

confidence: 99%

High Surface Area Mesoporous Activated Carbon from Hemp Bast Fibre Using Hydrothermal Processing

Hossain¹,

Wu²,

Xu³

et al. 2018

Preprint

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Synthesis of activated carbon from waste biomass is of current interest towards sustainability.The properties of biomass derived activated carbon largely depends on the carbonization process. This study reports preparing extremel high surface area mesoporous activated carbon from hemp bast fibre using hydrothermal processing. Processing in hot water (390-500 o C), then activation using KOH and NaOH was investigated at different loading ratios. The described approach was found to enhance the mesoporosity (centered at 3.0 to 4.5 nm) of the hemp derived activated carbon (HAC) from activation (confirmed by BJH pore size distribution and TEM imaging). BET results showed that the product has an extremely high surface area (2425 m 2 /g) while the surface functional groups (-OH, COOH, C=C/C-C) were confirmed and quantified by XPS and FTIR results. Increasing KOH concentration was found to enhance the surface area with an optimum biochar to KOH ratio of 1:3. The crystallite domain size of HAC was determined using Raman spectroscopy of different wavelengths. The procedure described in this study is an environmentally friendly scalable route for the mass production of activated carbon using hemp fiber.

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