scholarly journals Catalytic Effect of NaCl on the Improvement of the Physicochemical Structure of Coal-Based Activated Carbons for SO2 Adsorption

Processes ◽  
2019 ◽  
Vol 7 (6) ◽  
pp. 338 ◽  
Author(s):  
Dongdong Liu ◽  
Rui Su ◽  
Zhengkai Hao ◽  
Xiaoman Zhao ◽  
Boyin Jia ◽  
...  
Keyword(s):  
Functional Groups ◽  
Active Sites ◽  
Catalytic Effect ◽  
High Efficiency ◽  
Activated Carbons ◽  
Rapid Development ◽  
Adsorptive Capacity ◽  
Oxygen Functional Groups ◽  
So2 Adsorption ◽  
Physicochemical Structure

The utilization of coal-based activated carbons focuses on improving the physicochemical structure for achieving high-capacity. Herein, the catalytic effect of NaCl (1 and 3 wt%) in the presence of oxygen functional groups on the improvement of the physicochemical structure of coal-based activated carbons is studied in this work. A large quantity of Na can be retained in 1NaJXO and 3NaJXO with the presence of oxygen functional groups to promote further its catalytic characteristics during pyrolysis, resulting in the disordered transformation of the carbon structure. In addition, the development of micropores is mainly affected by the distribution and movement of Na catalyst, whereas the growth of mesopores is mainly influenced by the evolution of oxygen functional groups. Then, the active sites of 3NaJXO-800 can no longer be consumed preferentially in the presence of Na catalyst during subsequent CO2 activation to facilitate the sustained disordered conversion of the microstructure and the rapid development of the micropores, resulting in the obvious high SBET value as activation proceeds. And the high SBET/burn-off ratio value (41.48 m2∙g−1/%) of 3NaJXO-800 with a high value of SBET (1995.35 m2∙g−1) at a low burn-off value (48.1%) can be obtained, presenting the high efficiency of pore formation. Finally, the SO2 adsorption efficiency of 3NaJXO-800-48.1 maintains at 100% within 90 min. After 180 min, 3NaJXO-800-48.1 still presents a high adsorptive capacity (140.2 mg/g). It is observed that a large micropore volume in the case of hierarchical pore structure necessarily assures optimal adsorption of SO2.

scholarly journals The Analysis of Pore Development and Formation of Surface Functional Groups in Bamboo-Based Activated Carbon during CO2 Activation

Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5641
Author(s):  
Krittamet Phothong ◽  
Chaiyot Tangsathitkulchai ◽  
Panuwat Lawtae
Keyword(s):  
Activated Carbon ◽  
Functional Groups ◽  
Active Sites ◽  
Activated Carbons ◽  
Carbonization Temperature ◽  
Activation Process ◽  
Activation Time ◽  
Oxygen Functional Groups ◽  
Porous Properties ◽  
Activation Conditions

Pore development and the formation of oxygen functional groups were studied for activated carbon prepared from bamboo (Bambusa bambos) using a two-step activation with CO2, as functions of carbonization temperature and activation conditions (time and temperature). Results show that activated carbon produced from bamboo contains mostly micropores in the pore size range of 0.65 to 1.4 nm. All porous properties of activated carbons increased with the increase in the activation temperature over the range from 850 to 950 °C, but decreased in the temperature range of 950 to 1000 °C, due principally to the merging of neighboring pores. The increase in the activation time also increased the porous properties linearly from 60 to 90 min, which then dropped from 90 to 120 min. It was found that the carbonization temperature played an important role in determining the number and distribution of active sites for CO2 gasification during the activation process. Empirical equations were proposed to conveniently predict all important porous properties of the prepared activated carbons in terms of carbonization temperature and activation conditions. Oxygen functional groups formed during the carbonization and activation steps of activated carbon synthesis and their contents were dependent on the preparation conditions employed. Using Boehm’s titration technique, only phenolic and carboxylic groups were detected for the acid functional groups in both the chars and activated carbons in varying amounts. Empirical correlations were also developed to estimate the total contents of the acid and basic groups in activated carbons in terms of the carbonization temperature, activation time and temperature.

scholarly journals Isotherm and Kinetic Modeling of Strontium Adsorption on Graphene Oxide

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2780
Author(s):  
Abdulrahman Abu-Nada ◽  
Ahmed Abdala ◽  
Gordon McKay
Keyword(s):  
Graphene Oxide ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Nitrogen Adsorption ◽  
Order Kinetic ◽  
X Ray ◽  
Oxygen Functional Groups ◽  
Bet Analysis

In this study, graphene oxide (GO) was synthesized using Hummers method. The synthesized GO was characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) nitrogen adsorption. The analyses confirmed the presence of oxygen functional groups (C=O and C-O-C) on the GO surface. These oxygen functional groups act as active sites in the adsorption Sr (II). The BET analysis revealed the surface area of GO of 232 m2/g with a pore volume of 0.40 cm3/g. The synthesized GO was used as an adsorbent for removing Sr (II) from aqueous solutions. The adsorption equilibrium and kinetic results were consistent with the Langmuir isotherm model and the pseudo-second-order kinetic model. A maximum strontium adsorption capacity of 131.4 mg/g was achieved. The results show that the GO has an excellent adsorption capability for removing Sr (II) from aqueous solutions and potential use in wastewater treatment applications.

scholarly journals Role of Activated Carbon Precursor for Mercury Oxidation and Removal: Oxidized Surface and Carbene Site Interaction

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1190
Author(s):  
Regina Rodriguez ◽  
Domenic Contrino ◽  
David Mazyck
Keyword(s):  
Activated Carbon ◽  
Nitric Acid ◽  
Gas Phase ◽  
Functional Groups ◽  
Bituminous Coal ◽  
Activated Carbons ◽  
Elemental Mercury ◽  
Coconut Shell ◽  
Mercury Removal ◽  
Oxygen Functional Groups

Activated carbon (AC) is widely accepted for the removal of inorganic contaminants like mercury; however, the raw material used in the production of activated carbon is not always taken into consideration when evaluating its efficacy. Mercury oxidation and adsorption mechanisms governed by carbene sites are more likely to occur when graphitic-like activated carbons (such as those produced from high-ranking coals) are employed versus lignocellulosic-based ACs; this is likely due to the differences in carbon structures where lignocellulosic materials are less aromatic. In this research, the team studied bituminous coal-based ACs in comparison to coconut shell and wood-based (both less aromatic) ACs for elemental mercury removal. Nitric acid of 0.5 M, 1 M, and 5 M concentrations along with 10 M hydrogen peroxide were used to oxidize the surface of the ACs. Boehm titrations and FTIR analysis were used to quantify the addition of functional groups on the activated carbons. A trend was observed herein, resulting in increasing nitric acid molarity and an increased quantity of oxygen-containing functional groups. Gas-phase mercury removal mechanisms including physisorption, oxygen functional groups, and carbene sites were evaluated. The results showed significantly better elemental mercury removal in the gas phase with a bituminous coal-based AC embodying similar physical and chemical characteristics to that of its coconut shell-based counterpart. The ACs treated with various oxidizing agents to populate oxygen functional groups on the surface showed increased mercury removal. It is hypothesized that nitric acid treatment creates oxygen functional groups and carbene sites, with carbene sites being more responsible for mercury removal. Heat treatments post-oxidation with nitric acid showed remarkable results in mercury removal. This process created free carbene sites on the surface and shows that carbene sites are more reactive to mercury adsorption than oxygen. Overall, physisorption and oxygen functional groups were also dismissed as mercury removal mechanisms, leaving carbene-free sites as the most compelling mechanism.

Adsorption of volatile sulphur compounds onto modified activated carbons: Effect of oxygen functional groups

2013 ◽  
Vol 258-259 ◽  
pp. 77-83 ◽  
Author(s):  
Esther Vega ◽  
Jesús Lemus ◽  
Alba Anfruns ◽  
Rafael Gonzalez-Olmos ◽  
José Palomar ◽  
...  
Keyword(s):  
Functional Groups ◽  
Activated Carbons ◽  
Sulphur Compounds ◽  
Oxygen Functional Groups ◽  
Volatile Sulphur Compounds ◽  
Effect Of Oxygen ◽  
Modified Activated Carbons

Adsorption of quinoline from liquid hydrocarbons on graphite oxide and activated carbons

RSC Advances ◽  
2015 ◽  
Vol 5 (91) ◽  
pp. 74684-74691 ◽  
Author(s):  
Xiao Feng ◽  
Xiaoliang Ma ◽  
Na Li ◽  
Chao Shang ◽  
Xiaoming Yang ◽  
...  
Keyword(s):  
Functional Groups ◽  
Graphite Oxide ◽  
Activated Carbons ◽  
Liquid Hydrocarbons ◽  
Oxygen Functional Groups

Graphite oxide might be a promising adsorbent for adsorption denitrogenation due to its significant amount of oxygen functional groups.

Effects of Pre-Carbonization on Structure and Electrochemical Performances of Amphiphilic Carbonaceous Material-Based Activated Carbons

2012 ◽  
Vol 549 ◽  
pp. 96-100
Author(s):  
Cui Zhang ◽  
Cheng Yang Wang ◽  
Ming Ming Chen ◽  
Jia Ming Zheng ◽  
Jiu Zhou Wang
Keyword(s):  
Functional Groups ◽  
Active Sites ◽  
Activated Carbons ◽  
Carbonaceous Material ◽  
Alkaline Solutions ◽  
Electrochemical Performances ◽  
Activation Process ◽  
Xps Spectra ◽  
Electrochemical Double Layer ◽  
Two Parameters

Activated carbons to be used as electrode in electrochemical double-layer capacitors were fabricated using amphiphilic carbonaceous material (ACM) as precursor. To study the significance of functional groups and microcrystalline of the precursor in preparing AC, we applied pre-carbonization upon the ACM under different conditions to control these two parameters in this paper. FTIR and XPS spectra showed functional groups on the precursors decreased as the increase of pre-carbonization temperature. After carbonization at 800 °C, the growth of graphitic microcrystallites was noticeable. Porous structure parameters of final ACs inferred that the functional groups on the precursors have a more significant effect than microcrystalline size on formation of mesopores during activation process not only for its role as active sites but also the homogeneous activation profited from the solubility of samples in alkaline solutions. The sample AC0 with almost half mesopores showed the best electrochemical behavior with a specific gravimetric capacitance of 255 F/g at current density of 1000mA/g and kept rectangular shape cyclic voltammetry curve even at scan rate high as 400 mV/s.

scholarly journals Effect of Physical and Mechanical Activation on the Physicochemical Structure of Coal-Based Activated Carbons for SO2 Adsorption

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 707 ◽  
Author(s):  
Liu ◽  
Hao ◽  
Zhao ◽  
Su ◽  
Feng ◽  
...  
Keyword(s):  
Mechanical Activation ◽  
Ball Milling ◽  
Oxygen Content ◽  
Milling Time ◽  
Activated Carbons ◽  
Defective Structure ◽  
Dry Ice ◽  
So2 Adsorption ◽  
Physicochemical Structure ◽  
Ball Milling Time

The SO2 adsorption efficiency of activated carbons (ACs) is clearly dependent on its physicochemical structure. Related to this, the effect of physical and mechanical activation on the physicochemical structure of coal-based ACs has been investigated in this work. In the stage of CO2 activation, the rapid decrease of the defective structure and the growth of aromatic layers accompanied by the dehydrogenation of aromatic rings result in the ordered conversion of the microstructure and severe carbon losses on the surfaces of Char-PA, while the oxygen content of Char-PA, including C=O (39.6%), C–O (27.3%), O–C=O (18.4%) and chemisorbed O (or H2O) (14.7%), is increased to 4.03%. Char-PA presents a relatively low SBET value (414.78 m2/g) owing to the high value of Non-Vmic (58.33%). In the subsequent mechanical activation from 12 to 48 h under N2 and dry ice, the strong mechanical collision caused by ball-milling can destroy the closely arranged crystalline layers and the collapse of mesopores and macropores, resulting in the disordered conversion of the microstructure and the formation of a defective structure, and a sustained increase in the SBET value from 715.89 to 1259.74 m2/g can be found with the prolonging of the ball-milling time. There is a gradual increase in the oxygen content from 6.79 to 9.48% for Char-PA-CO2-12/48 obtained by ball-milling under CO2. Remarkably, the varieties of physicochemical parameters of Char-PA-CO2-12/48 are more obvious than those of Char-PA-N2-12/48 under the same ball-milling time, which is related to the stronger solid-gas reactions caused by the mechanical collision under dry ice. Finally, the results of the SO2 adsorption test of typical samples indicate that Char-PA-CO2-48 with a desirable physicochemical structure can maintain 100% efficiency within 30 min and that its SO2 adsorption capacity can reach 138.5 mg/g at the end of the experiment. After the 10th cycle of thermal regeneration, Char-PA-CO2-48 still has a strong adsorptive capacity (81.2 mg/g).

scholarly journals High activity carbon sorbents for mercury capture

2006 ◽  
Vol 10 (3) ◽  
pp. 19-26
Author(s):  
George Stavropoulos ◽  
Irene Diamantopoulou ◽  
George Skodras ◽  
George Sakellaropoulos
Keyword(s):  
Adsorption Capacity ◽  
Active Sites ◽  
High Efficiency ◽  
Activated Carbons ◽  
Breakthrough Curves ◽  
Mercury Adsorption ◽  
Retention Capacity ◽  
Gas Streams ◽  
Mercury Capture ◽  
Materials Used

High efficiency activated carbons have been prepared for removing mercury from gas streams. Starting materials used were petroleum coke, lignite, charcoal and olive seed waste, and were chemically activated with KOH. Produced adsorbents were primarily characterized for their porosity by N2 adsorption at 77 K. Their mercury retention capacity was characterized based on the breakthrough curves. Compared with typical commercial carbons, they have exhibited considerably enhanced mercury adsorption capacity. An attempt has been made to correlate mercury entrapment and pore structure. It has been shown that physical surface area is increased during activation in contrast to the mercury adsorption capacity that initially increases and tends to decrease at latter stages. Desorption of active sites may be responsible for this behavior.

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