BET Surface Area Of Activated Carbon Research Articles

Activated carbon/metal-organic framework nanocomposite: Preparation and photocatalytic dye degradation mathematical modeling from wastewater by least squares support vector machine

Herein, Kiwi peel activated carbon (AC), Materials Institute Lavoisier (MIL-88B (Fe), and AC/MIL-88B (Fe) composite were synthesized and used as catalysts to degrade Reactive Red 198. The material properties were analyzed by the FTIR, BET-BJH, XRD, FESEM, EDX, TGA, and UV–Vis/DRS. The BET surface area of AC, MIL-88B (Fe) and AC/MIL-88B (Fe) was 1113.3, 150.7, and 199.4 m2/g, respectively. The band gap values (Eg) estimated by Tauc plot method, were obtained 5.06, 4.19 and 3.79 eV for AC, MIL-88B (Fe) and AC/MIL-88B (Fe), respectively. The results indicated that the AC/MIL-88B (Fe) composite had higher photocatalytic activity (99%) than that of pure AC (79%) and MIL-88B (Fe) catalysts (87%). The decolorization kinetic was matched well with the second-order model. Moreover, the data were modeled using least squares support vector machine which optimized with Cuckoo optimization algorithm. The optimal parameters were found 0.837 and 3.49e+02 based on σ2 and γ values, respectively. The mean square error (MSE) and correlation coefficient (R2) values were obtained 3.97 and 0.948. Therefore, the attained data, materials characterization and prediction of modeling validate the composite form of MIL-88B(Fe) with new AC, had better photocatalytic activity in comparison with the individual form.

Activated carbon/metal-organic framework composite as a bio-based novel green adsorbent: Preparation and mathematical pollutant removal modeling

Herein, the novel green MOF's nanocomposite based on cucumber peel activated carbon (AC) and chromium-based metal-organic framework (MIL-101(Cr)) with different AC ratios (2, 5 and 10 wt%) was synthesized and used for removing Acid Green 25 (AG25) and Reactive Yellow 186 (RY186) dyes from the binary systems. The characterization of materials was done using TGA, BET, XRD, SEM, and FTIR. The SEM images of MIL-101 showed octahedral crystal structure and composite materials exhibited the same morphology as MIL-101(Cr) crystals on an activated carbon bed. The BET surface area of AC and AC/MIL-101(Cr)_5% was measured 1096.83 and 2412.1 m2/g, respectively. The results showed that the Response Surface Methodology (RSM) model predicted the actual data with high correctness. The reliability of the RSM model was validated by the high values of R2 (AG25: 0.961 and RY186: 0.957). The obtained data from this research are well-fitted with the Langmuir isotherm and the pseudo-second order kinetics. The desorption process indicates that the adsorption capacity changes are <9% after five cycles.

Drying before microwave-assisted H3PO4 activation to produce highly mesoporous activated carbons

Activated carbons (ACs) were prepared by drying at temperatures of 60–285 °C before microwave-assisted activation to investigate effects of predying on their properties. The predrying affected ACs' P-containing functional groups, structural defects, and textural properties. The mesopore volume, total pore volume, and BET surface area of ACs peaked when predrying temperature was 250 °C (1.05 mL/g, 1.26 mL/g, and 1509 m2/g), mainly because predrying changed microwave activation temperature. The mesopore volume ranked among the highest values ever reported for ACs prepared by microwave activation with P-containing agents; the corresponding mesopore fraction (83.3%) was also large, compared with that of many reported ACs. The drying before microwave activation is an effective strategy to prepare ACs with both superior mesopore volume and high mesopore fraction.

Adsorption of Antimony by Bagasse Fly Ash: Chemical Modification and Adsorption Mechanism.

Modification of bagasse fly ash (BFA) and the adsorption mechanism of antimony (Sb) by modified BFA were studied. It was found that BFA grafted with acrylic acid (BFAG) and BFA treated with hydrochloric acid (BFA/HCl) led to a decrease in the pH of the zero point of charge (pHzpc) of the adsorbents. The pHzpc of BFA, BFAG, BFA/HCl and activated carbon (AC) were 8.3, 6.4, 6.2 and 8.2, respectively. The maximum adsorption capacities (Qmax) of Sb by BFA, BFAG, BFA/HCl and AC were 0.14, 0.34, 0.38 and 0.29 mg Sb/g adsorbent, respectively. Modified BFA had Qmax higher than AC although the BET surface area of AC was the highest. This was due to the system pH of BFAG and BFA/HCl was 5.20-6.00 and the pHzpc of BFAG and BFA/HCl accounted for 6.4 and 6.2, respectively. Therefore, the adsorbent surface had a positive charge, resulting in increasing adsorption of Sb.

Influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for the synthesis of dimethyl carbonate

Activated carbon (AC) supported Cu catalysts are employed to study the influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for oxidative carbonylation of methanol to dimethyl carbonate (DMC). The AC supports are thermal treated under different temperatures in order to adjust the levels of surface oxygenated groups. The AC supports are characterized by BET, TPD-MS and XRD, and the Cu/AC catalysts are characterized by BET, XRD, TEM, XPS, AAS, CH3OH-TPD and N2O chemisorption. The results show that as the treatment temperature is below 800°C, the BET surface area of the corresponding AC supports are nearly unchanged and close to that of the original AC (1529.6m2/g). But as the thermal treatment temperature is elevated from 1000 to 1600°C, the BET surface area of AC supports gradually decreases from 1407.6 to 972.2m2/g. After loading of Cu, the BET surface area of copper catalysts is in the range of 834.4 to 1545.3m2/g, which is slightly less than that of the respective supports. When AC is thermal treated at 400 and 600°C, the unstable carboxylic acid and anhydrides groups are selectively removed, which has weakened the mobility and agglomeration of Cu species during the calcination process, and thus improve the Cu species dispersion over AC support. But as the treatment temperature is elevated from 600°C to 1200°C, the Cu species dispersion begins to decline suggesting further removal of stable surface oxygenated groups is unfavorable for Cu species dispersion. Moreover, higher thermal treatment temperature (above 1200°C) promotes the graphitization degree of AC and leds to the decrease of Cu loading on AC support. Meanwhile, the removal of surface oxygenated groups by thermal treatment is conducive to the formation of more π-sites, and thus promote the reduction of Cu2+ to Cu+ and Cu0 as active centers. The specific surface area of (Cu++Cu0) is improved by thermal treatment of AC, however, the space time yield of DMC on unit specific surface area of (Cu++Cu0) is in the range of 23.1–49.1mgh−1m−2, which is much less than that (77.6mgh−1m−2) of the original catalyst. The possible reason is that the removal of surface oxygenated groups results in AC support transforms from hydrophilicity to hydrophobicity, which is detrimental for the adsorption of CH3OH resulting in the decreased local concentration of CH3OH on active Cu species.

The Formaldehyde Removal by Commercial Activated Carbons at Room Temperature

The adsorption performance of commercial activated carbon (AC) for formaldehyde at room temperature was investigated. The BET surface area of AC is 805 m2/g, and the average pore diameter of AC was found to be 2.9 nm by the nitrogen adsorption method. The result of the adsorption capacity of AC showed that the removal ratio of formaldehyde was obviously increased with adsorption time in the first 5 hours and then was almost unchanged. The highest removal ratio of formaldehyde by AC is ~92%. The cycle test of the formaldehyde removal by AC indicated that the highest removal ratio of formaldehyde declined slightly with cycles and kept unchanged after 4 cycles. The lowest removal ratio of formaldehyde by commercial AC at room temperature still reached 80%.

Microwave-Alkali Activation on the Morphology and Structure of Bamboo Activated Carbon

A study was conducted for production of activated carbon (AC) from industrial bamboo waste using carbonization and Microwave-alkali (Mw-A) activation techniques. The aim of the study is to produce activated carbon with higher surface area via Mw-A activation techniques. The study was focused on the effect of activation (KOH soaking and Mw-A) and carbonization temperature (400oC and 500oC) on the physical and chemical structure of AC. The analysis was conducted using proximate analysis, BET surface area, FESEM and FTIR analysis. The morphology and characteristic study on activated carbon shown that Mw-A activation techniques gave higher BET surface area and well develop pore structure. The results indicated that Mw-A activation of activated carbon gave BET surface area of 950m2g-1, whereas by using steam activation only 719 m2g-1 of BET surface area was recorded. Higher carbonization temperature for Mw-A treated bamboo produced higher surface area of AC. At 500oC, 1578m2g-1 BET surface area of AC was achieved. This work highlighted, Mw-A activation can be applied and further enhanced to obtain higher surface area of activated carbon derived from industrial bamboo waste.

Partial oxidation of municipal sludge with activited carbon catalyst in supercritical water

The partial oxidation (POX) characteristics of municipal sludge in supercritical water (SCW) were investigated by using batch reactor. Effects of reaction parameters such as oxidant equivalent ratio (OER), reaction time and temperature were investigated. Activated carbon (AC) could effectively improve the mole fraction of H 2 in gas product at low OER. However, high OER (greater than 0.3) not only led to the combustion reaction of CO and H 2, but also caused corrosion of reactor inner wall. Hydrogenation and polymerization of the intermediate products are possible reasons for the relative low COD removal rate in our tests. Metal oxide leached from the reactor inner wall and the main components of the granular sludge were deposited in the AC catalyst. Reaction time had more significant effect on BET surface area of AC than OER had. Long reaction time led to the methanation reaction following hydrolysis and oxidation reaction of AC in SCW in the presence of oxygen. Correspondingly, the possible reaction mechanisms were proposed.

Effect of pore size distribution of coal-based activated carbons on double layer capacitance

A series of coal-based activated carbons representing a wide range of mesopore content, from 16.7 to 86.9%, were investigated as an electrode in electric double layer capacitors (EDLCs) in 1 mol l −1 H 2SO 4 and 6 mol l −1 KOH electrolytic solutions. The activated carbons (ACs) used in this study were produced from chemically modified lignite, subbituminous and bituminous coals by carbonization and subsequent activation with steam. The BET surface area of ACs studied ranged from 340 to 1270 m 2 g −1. The performance of ACs as EDLC electrodes was characterized using voltammetry, galvanostatic charge/discharge and impedance spectroscopy measurements. For the carbons with surface area up to 1000 m 2 g −1, the higher BET surface area the higher specific capacitance (F g −1) for both electrolytes. The surface capacitance (μF cm −2) increases also with the mesopore content. The optimum range of mesopore content in terms of the use of ACs studied for EDLCs was found to be between 20 and 50%. A maximum capacitance exceeding 160 F g −1 and a relatively high surface capacitance about 16 μF cm −2 measured in H 2SO 4 solution were achieved for the AC prepared from a sulfonated subbituminous coal. This study shows that the ACs produced from coals exhibit a better performance as an electrode material of EDLC in H 2SO 4 than in KOH electrolytic solutions. For KOH, the capacitance per unit mesopore surface is slightly lower than that referred to unit micropore surface (9.1 versus 10.1 μF cm −2). However, in the case of H 2SO 4 the former capacitance is double and even higher compared with the latter (23.1 versus 9.8 μF cm −2). On the other hand, the capacitance per micropore surface area is the same in both electrolytes used, about 10.0 μF cm −2.