Phosphoric acid pretreatment enhances the specific surface areas of biochars by generation of micropores

Chu, Gang; Zhao, Jing; Huang, Yu; Zhou, Dandan; Liu, Yang; Wu, Min; Peng, Hongbo; Zhao, Qing; Pan, Bo; Steinberg, Christian E. W.

doi:10.1016/j.envpol.2018.04.003

Cited by 215 publications

(65 citation statements)

References 46 publications

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“…Another study showed that paper mill sludge as biochar feedstock, pre-treated with phosphoric acid and torrefaction, followed by pyrolysis, resulted in reduced volatile matter content, increased inorganic matter, and increased biochar yield [40]. It was shown that biochar made from feedstock with pretreatments such as light bio-oil or phosphoric acid may have larger surface areas and more porous structure [41,42], which could influence the effects of biochar on air space, nutrient and water-holding ability, and microbial activity. Biochar made from bark pre-treated with tannery slurry as an alkaline treatment could have a higher NH4 + absorption capacity, as well as more surface functional groups (carboxyl and carbonyl groups) formed than untreated ones [43], causing increased CEC of biochar.…”

Section: Biochar Production Methodsmentioning

confidence: 99%

Effects of Biochar on Container Substrate Properties and Growth of Plants—A Review

Huang

Gu²

2019

Horticulturae

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Biochar refers to a processed, carbon-rich material made from biomass. This article provides a brief summary on the effects of biochar on container substrate properties and plant growth. Biochar could be produced through pyrolysis, gasification, and hydrothermal carbonization of various feedstocks. Biochar produced through different production conditions and feedstocks affect its properties and how it performs when incorporated in container substrates. Biochar incorporation affects the physical and chemical properties of container substrates, including bulk density, total porosity, container capacity, nutrient availability, pH, electrical conductivity and cation exchange capacity. Biochar could also affect microbial activities. The effects of biochar incorporation on plant growth in container substrates depend on biochar properties, plant type, percentage of biochar applied and other container substrates components mixed with biochar. A review of the literature on the impact of biochar on container-grown plants without other factors (such as irrigation or fertilization rates) indicated that 77.3% of the studies found that certain percentages of biochar addition in container substrates promoted plant growth, and 50% of the studies revealed that plant growth decreased due to certain percentages of biochar incorporation. Most of the plants tested in these studies were herbaceous plants. More plant species should be tested for a broader assessment of the use of biochar. Toxic substances (heavy metals, polycyclic aromatic hydrocarbons and dioxin) in biochars used in container substrates has rarely been studied. Caution is needed when selecting feedstocks and setting up biochar production conditions, which might cause toxic contaminants in the biochar products that could have negative effects on plant growth.

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Section: Biochar Production Methodsmentioning

confidence: 99%

Effects of Biochar on Container Substrate Properties and Growth of Plants—A Review

Huang

Gu²

2019

Horticulturae

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“…Given its production conditions, biochar must be modified using chemical or physical activation, in order to increase its BET surface area. Chu et al investigated chemical activation using H 3 PO 4 . They reported that mixing biochar with H 3 PO 4 , followed by carbonization at 350°C, increased SSA from 9 m 2 ⋅ g −1 to 795 m 2 ⋅ g −1 .…”

Section: Applicationsmentioning

confidence: 99%

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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“…The adsorption capacity was pH dependent, confirming the active adsorption site of oxygen-containing functional groups on biochars surface. The H 3 PO 4 treatment prior to pyrolysis of pine tree sawdust increased the total pore volume and the content of micropores (Chu et al 2018;Zhao et al 2017). The P-O bond formed in the C structure acted like a backbone to prevent micropores clap during the pyrolysis, which enhanced the adsorption capacity for organic pollutants (Chu et al 2018).…”

Section: Chemical Modificationmentioning

confidence: 99%

“…The H 3 PO 4 treatment prior to pyrolysis of pine tree sawdust increased the total pore volume and the content of micropores (Chu et al 2018;Zhao et al 2017). The P-O bond formed in the C structure acted like a backbone to prevent micropores clap during the pyrolysis, which enhanced the adsorption capacity for organic pollutants (Chu et al 2018). Oxidation with H 2 O 2 is another common method used to modify biochars (Wang et al 2015(Wang et al , 2016(Wang et al , 2018c.…”

Section: Chemical Modificationmentioning

confidence: 99%

Environmental behavior of engineered biochars and their aging processes in soil

Duan

Oleszczuk

Pan

et al. 2019

Biochar

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In recent years, due to the broad application of biochars, the preparation, environmental behavior and aging processes of biochars have attracted wide attention globally, especially the modification of biochars. However, most of the studies only consider the improvement of biochar properties right after the modification, but neglect a complete evaluation of the longterm stability and eco-toxicity of these newly developed materials after entering the environment. With the development and utilization of biochars, engineered biochars (EngBCs) will soon enter the market, but its environmental risk still remains unclear. The literature does not provide adequate information on how aging of EngBCs will affect their properties, and indirectly impact the properties of soils (cycle of elements and organic matter). Therefore, this review paper summarizes the aging process and environmental risk of biochars, aiming at better understanding the interactions between EngBCs and soil components or pollutants. More importantly, this review is to point out the contradictory speculations of environmental behavior of EngBCs studied at the present stage. Due to the modification, the EngBCs stability may be significantly reduced. However, the formation of functional group on EngBCs will enhance their interaction with soil minerals to form biocharsmineral complex, and thus EngBCs could be protected. The impacts of EngBCs after entering the environment are also ambiguous. Therefore, understanding EngBCs environmental behavior is critical, which is helpful to reduce the potential risk and to produce EngBCs following the rule of sustainable development and safety to the environment.

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Phosphoric acid pretreatment enhances the specific surface areas of biochars by generation of micropores

Cited by 215 publications

References 46 publications

Effects of Biochar on Container Substrate Properties and Growth of Plants—A Review

Effects of Biochar on Container Substrate Properties and Growth of Plants—A Review

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

Environmental behavior of engineered biochars and their aging processes in soil

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