Soil moisture adsorption capacity and specific surface area in relation to water vapor pressure in arid and tropical soils

The surfaces of carbon molecular sieves (CMSs) were thermally fluorinated to adsorb water vapor. The fluorination of the CMSs was performed at various temperatures (100, 200, 300, and 400°C) to investigate the effects of the fluorine gas (F2) content on the surface properties. Fluorine-related functional groups formed were effectively generated on the surface of the CMSs via thermal fluorination process, and the total pore volume and specific surface area of the pores in the CMSs increased during the thermal fluorination process, especially those with diameters ≤ 8 Å. The water vapor adsorption capacity of the thermally fluorinated CMSs increased compared with the as-received CMSs, which is attributable to the increased specific surface area and to the semicovalent bonds of the C–F groups.

Download Full-text

Organic Robotics Based on Conducting Polymers

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.79.87 ◽

2012 ◽

Vol 79 ◽

pp. 87-93

Author(s):

Hidenori Okuzaki

Keyword(s):

Water Vapor ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Colloidal Particles ◽

Water Vapor Pressure ◽

Isosteric Heat ◽

Water Vapor Sorption ◽

Vapor Sorption ◽

Free Standing

Free-standing films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) were prepared by casting water dispersion of its colloidal particles. Specific surface area, water vapor sorption, and electro-active polymer actuating behavior of the resulting films were investigated by means of sorption isotherm, and electromechanical analysis. It was found that the non-porous PEDOT/PSS film, having a specific surface area of 0.13 m2/g, sorbed water vapor of 1080 cm3(STP)/g, corresponding to 87 wt%, at relative water vapor pressure of 0.95. A temperature rise from 25 to 40 °C lowered sorption degree, indicative of an exothermic process, where isosteric heat of sorption decreased with increasing water vapor sorption and the value reached 43.9 kJ/mol, being consistent with the heat of water condensation (44 kJ/mol). Upon application of 10 V, the film underwent contraction of 2.4% in air at 50% relative humidity (RH) which significantly increased to 4.5% at 90% RH. The principle lay in desorption of water vapor sorbed in the film due to Joule heating, where electric field was capable of controlling the equilibrium of water vapor sorption.

Download Full-text

Study of the Porous Structure and High Adsorption Capacity of Biomass-Based Activated Carbon Prepared from Aspen Wood by Ferric Nitrate III Activation

Journal of Biobased Materials and Bioenergy ◽

10.1166/jbmb.2021.2047 ◽

2021 ◽

Vol 15 (2) ◽

pp. 131-144

Author(s):

Chunjiang Jin ◽

Huimin Chen ◽

Luyuan Wang ◽

Xingxing Cheng ◽

Donghai An ◽

...

Keyword(s):

Activated Carbon ◽

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Pore Volume ◽

Mass Ratio ◽

Aspen Wood ◽

Surface Functional Groups ◽

Wood Sawdust

In this study, aspen wood sawdust was used as the raw material, and Fe(NO3)3 and CO2 were used as activators. Activated carbon powder (ACP) was produced by the one-step physicochemical activation method in an open vacuum tube furnace. The effects of different mass ratios of Fe(NO3)3 and aspen wood sawdust on the pore structure of ACP were examined under single-variable experimental conditions. The mass ratio was 0–0.4. The detailed characteristics of ACP were examined by nitrogen adsorption, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The adsorption capacity of ACP was established by simulating volatile organic compounds (VOCs) using ethyl acetate. The results showed that ACP has a good nanostructure with a large pore volume, specific surface area, and surface functional groups. The pore volume and specific surface area of Fe-AC-0.3 were 0.26 cm3/g and 455.36 m2/g, respectively. The activator played an important role in the formation of the pore structure and morphology of ACP. When the mass ratio was 0–0.3, the porosity increased linearly, but when it was higher than 0.3, the porosity decreased. For example, the pore volume and specific surface area of Fe-AC-0.4 reached 0.24 cm3/g and 430.87 m2/g, respectively. ACP presented good VOC adsorption performance. The Fe-AC-0.3 sample, which contained the most micropore structures, presented the best adsorption capacity for ethyl acetate at 712.58 mg/g. Under the action of the specific reaction products nitrogen dioxide (NO2) and oxygen, the surface of modified ACP samples showed different rich C/O/N surface functional groups, including C-H, C=C, C=O, C-O-C, and C-N.

Download Full-text

Correlation of the Specific Surface Area and Bulk Density of Commercial Charcoals with Their Adsorption Capacity for Radioactive Krypton and Xenon

Nuclear Science and Engineering ◽

10.13182/nse81-a19039 ◽

1981 ◽

Vol 79 (1) ◽

pp. 19-25 ◽

Cited By ~ 3

Author(s):

Dwight W. Underhill

Keyword(s):

Specific Surface ◽

Bulk Density ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area

Download Full-text

Adsorption of Ammonium Nitrogen from Aqueous Solution on Chemically Activated Biochar Prepared from Sorghum Distillers Grain

Applied Sciences ◽

10.3390/app9235249 ◽

2019 ◽

Vol 9 (23) ◽

pp. 5249 ◽

Cited By ~ 3

Author(s):

Derlin Hsu ◽

Changyi Lu ◽

Tairan Pang ◽

Yuanpeng Wang ◽

Guanhua Wang

Keyword(s):

Aqueous Solution ◽

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Adsorption Process ◽

Ammonium Nitrogen ◽

Activated Biochar ◽

Distillers Grain ◽

Kinetics And Isotherms

Chemically activated biochars prepared from sorghum distillers grain using two base activators (NaOH and KOH) were investigated for their adsorption properties with respect to ammonium nitrogen from aqueous solution. Detailed characterizations, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TG), and specific surface area analyses, were carried out to offer a broad evaluation of the prepared biochars. The results showed that the NaOH- and KOH-activated biochars exhibited significantly enhanced adsorption capacity, by 2.93 and 4.74 times, respectively, in comparison with the pristine biochar. Although the NaOH-activated biochar possessed larger specific surface area (132.8 and 117.7 m2/g for the NaOH- and KOH-activated biochars, respectively), the KOH-activated biochar had higher adsorption capacity owing to its much higher content of functional groups. The adsorption kinetics and isotherms of the KOH-activated biochar at different temperatures were further studied. The biochar had a maximum adsorption capacity of 14.34 mg/g at 45 °C, which was satisfactory compared with other biochars prepared using different feedstocks. The adsorption process followed pseudo-second-order kinetics, and chemical adsorption was the rate-controlling step. The equilibrium data were consistent with the Freundlich isotherm, and the thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Consequently, this work demonstrates that chemically activated biochar from sorghum distillers grain is effective for ammonium nitrogen removal.

Download Full-text

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

Materials ◽

10.3390/ma11122362 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2362 ◽

Cited By ~ 6

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.

Download Full-text

Using Activated Diatomite as Adsorbent for Treatment of Arsenic Contaminated Water

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.850.16 ◽

2020 ◽

Vol 850 ◽

pp. 16-21

Author(s):

Hoc Thang Nguyen ◽

Phong Thanh Dang

Keyword(s):

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Contaminated Water ◽

Viet Nam ◽

High Porosity ◽

Room Condition ◽

Main Chemical Composition ◽

Adsorbent Capacity

Diatomite or diatomaceous earth (DE) is one of materials which can be used as an adsorbent to treat heavy metal ions from waste water, even there are many factories used it to clean the water for drinking. However, natural DE (raw DE) has very low adsorption capacity because of low specific surface area. In this work, natural DE from Lam Dong province, Viet Nam was demagnetized to remove iron and activated by HCl solution for 90 minutes with concentration of 10% at room condition. Adsorbent capacity was evaluated using As solution and the results show that the activated diatomite has adsorption capacity three times higher than that of raw DE, and the specific surface area of activated diatomite was increased 47.5% with the main chemical composition of 90.8% SiO2 and high porosity

Download Full-text

Improve in CO2 and CH4 Adsorption Capacity on Carbon Microfibers Synthesized by Electrospinning of PAN

Fibers ◽

10.3390/fib7100081 ◽

2019 ◽

Vol 7 (10) ◽

pp. 81 ◽

Cited By ~ 3

Author(s):

Reyna Ojeda-López ◽

J. Marcos Esparza-Schulz ◽

Isaac J. Pérez-Hermosillo ◽

Armin Hernández-Gordillo ◽

Armando Domínguez-Ortiz

Keyword(s):

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Gas Adsorption ◽

Morphological Structure ◽

Different Temperatures ◽

Ch4 Adsorption ◽

Stabilization Temperature ◽

Carbon Microfibers

Carbon microfibers (CMF) has been used as an adsorbent material for CO2 and CH4 capture. The gas adsorption capacity depends on the chemical and morphological structure of CMF. The CMF physicochemical properties change according to the applied stabilization and carbonization temperatures. With the aim of studying the effect of stabilization temperature on the structural properties of the carbon microfibers and their CO2 and CH4 adsorption capacity, four different stabilization temperatures (250, 270, 280, and 300 °C) were explored, maintaining a constant carbonization temperature (900 °C). In materials stabilized at 250 and 270 °C, the cyclization was incomplete, in that, the nitrile groups (triple-bond structure, e.g., C≡N) were not converted to a double-bond structure (e.g., C=N), to form a six-membered cyclic pyridine ring, as a consequence the material stabilized at 300 °C resulting in fragile microfibers; therefore, the most appropriate stabilization temperature was 280 °C. Finally, to corroborate that the specific surface area (microporosity) is not the determining factor that influences the adsorption capacity of the materials, carbonization of polyacrylonitrile microfibers (PANMFs) at five different temperatures (600, 700, 800, 900, and 1000 °C) is carried, maintaining a constant temperature of 280 °C for the stabilization process. As a result, the CMF chemical composition directly affects the CO2 and CH4 adsorption capacity, even more directly than the specific surface area. Thus, the chemical variety can be useful to develop carbon microfibers with a high adsorption capacity and selectivity in materials with a low specific surface area. The amount adsorbed at 25 °C and 1.0 bar oscillate between 2.0 and 2.9 mmol/g adsorbent for CO2 and between 0.8 and 2.0 mmol/g adsorbent for CH4, depending on the calcination treatment applicated; these values are comparable with other material adsorbents of greenhouse gases.

Download Full-text

Preparation of phosphorus-doped boron nitride and its adsorption of heavy metals from flue gas

Royal Society Open Science ◽

10.1098/rsos.200079 ◽

2020 ◽

Vol 7 (8) ◽

pp. 200079

Author(s):

Yanlong Li ◽

Hongxi Li ◽

Rundong Li ◽

Xin Su ◽

Shengqiang Shen

Keyword(s):

Heavy Metals ◽

Boron Nitride ◽

Specific Surface ◽

Adsorption Capacity ◽

Surface Area ◽

Specific Surface Area ◽

Flue Gas ◽

Maximum Adsorption Capacity ◽

Addition Rate ◽

Phosphorus Doped

Boron nitride, also known as white graphene, has attracted extensive attention in the fields of adsorption, catalysis and hydrogen storage due to its excellent chemical properties. In this study, a phosphorus-doped boron nitride (P-BN) material was successfully prepared using red phosphorus as a dopant for the preparation of porous boron nitride precursors. The phosphorus content in the P-BN was adjusted based on the addition rate of phosphorus. The specific surface area of P-BN first increased and then decreased with increasing addition rate of phosphorus. The maximum specific surface area was 837.8 m 2 g −1 when the phosphorus addition rate was 0.50. The P-BN prepared in the experiments was used as an adsorbent, and its adsorption capacity for heavy metals from flue gas was investigated. In particular, P-BN presented a stronger adsorption selectivity for zinc compared with other heavy metals, and its adsorption capacity for zinc was 5–38 times higher than for other heavy metals. The maximum adsorption capacity of P-BN for zinc and copper in a single heavy metal atmosphere was 69.45 and 53.80 mg g −1 , respectively.

Download Full-text