scholarly journals Fabrication of Highly Microporous Structure Activated Carbon via Surface Modification with Sodium Hydroxide

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3954
Author(s):  
Mohd Sahfani Hafizuddin ◽  
Chuan Li Lee ◽  
Kit Ling Chin ◽  
Paik San H’ng ◽  
Pui San Khoo ◽  
...  

The aim of this study was to select the optimal conditions for the carbonization process followed by surface modification treatment with sodium hydroxide (NaOH) to obtain a highly microporous activated carbon structure derived from palm kernel shells (PKS) and coconut shells (CS). The effects of the carbonization temperature and NaOH concentration on the physiochemical properties, adsorption capability, specific surface area, surface morphology, and surface chemistry of PKS and CS were evaluated in this study. The results show that surface-modified activated carbons presented higher surface area values (CS: 356.87 m2 g−1, PKS: 427.64 m2 g−1), smaller pore size (CS: 2.24 nm, PKS: 1.99 nm), and larger pore volume (CS: 0.34 cm3 g−1, PKS: 0.30 cm3 g−1) than the untreated activated carbon, demonstrating that the NaOH surface modification was efficient enough to improve the surface characteristics of the activated carbon. Moreover, surface modification via 25% NaOH greatly increases the active functional group of activated carbon, thereby directly increasing the adsorption capability of activated carbon (CS: 527.44 mg g−1, PKS: 627.03 mg g−1). By applying the NaOH post-treatment as the ultimate surface modification technique to the activated carbon derived from PKS and CS, a highly microporous structure was produced.

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
S. G. Herawan ◽  
M. S. Hadi ◽  
Md. R. Ayob ◽  
A. Putra

Activated carbons can be produced from different precursors, including coals of different ranks, and lignocellulosic materials, by physical or chemical activation processes. The objective of this paper is to characterize oil-palm shells, as a biomass byproduct from palm-oil mills which were converted into activated carbons by nitrogen pyrolysis followed by CO2activation. The effects of no holding peak pyrolysis temperature on the physical characteristics of the activated carbons are studied. The BET surface area of the activated carbon is investigated using N2adsorption at 77 K with selected temperatures of 500, 600, and 700°C. These pyrolysis conditions for preparing the activated carbons are found to yield higher BET surface area at a pyrolysis temperature of 700°C compared to selected commercial activated carbon. The activated carbons thus result in well-developed porosities and predominantly microporosities. By using this activation method, significant improvement can be obtained in the surface characteristics of the activated carbons. Thus this study shows that the preparation time can be shortened while better results of activated carbon can be produced.


Author(s):  
V. Sivanandan Achari ◽  
A. S. Rajalakshmi ◽  
S. Jayasree ◽  
Raichel Mary Lopez

In this study, a new series of coconut shell based granular activated carbons (GAC) are prepared by impregnating with zirconium ions as zirconyl chloride and activated under superheated steam. These carbons are designated with activation temperature/ conditions as GAC 383 (activated at 383K), GACO 383 (HNO3 oxidised), GACZR 1273 (ZrOCl2 activated at 1273K) and GACOZR 1273 (HNO3 oxidised, ZrOCl2 activated at 1273K). Surface characteristics of these carbons are evaluated using Boehm titration methods, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction techniques (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The pore volume and the respective specific surface area of each carbon are determined by BET, I plot, Langmuir, Freundlich, and Dubinin-Radushkevich isotherms using N2 adsorption data at 77K. Analysis shows that zirconium ion enhances the surface area and porosity of granular activated carbon. The adsorption characteristics of newly prepared GAC are tested by solid-liquid equilibria using phenol as adsorbate. Equilibrium phenol adsorption data fitted to standard isotherm models of Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) equations. Adsorption constants and parameters indicate that zirconium impregnated granular activated carbons are relatively more efficient for the removal of phenol than the native carbon used.


2009 ◽  
Vol 62-64 ◽  
pp. 352-356 ◽  
Author(s):  
O.O. Ojo

Powdered activated carbons were produced from palm kernel shells, corn cobs and cow bones by carbonization, pulverization and activation. The resulting granule has a surface area of 430.04 m2/g, 4022.15 m2/g and 733.60 m2/g respectively with controlled pore size. The characterized surface area enables the carbon to absorb vapors from gases, and substances from liquids. The surface properties are function of the base materials used in the preparation. Determinations of their adsorptive capacities show that activated carbon prepared from corn cobs has the highest adsorptive capacity. The surface properties are function of the base materials used in the preparation. Determinations of their adsorptive capacities show that activated carbon prepared from corn cobs has the highest adsorptive capacity.


Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6067
Author(s):  
Mirosław Kwiatkowski

The results of the advanced computer analysis of the influence of time and gas atmosphere of the chemical activation process on the microporous structure formation of activated carbons prepared from oil palm shell via microwave irradiation and activation, using potassium hydroxide as an activation agent, are presented in this paper. The quenched solid density functional theory (QSDFT) and the new numerical clustering-based adsorption analysis (LBET) methods were used especially in the analysis of the microporous structure of the activated carbons, taking into account the surface heterogeneity, and the results obtained were confronted with the simple results achieved earlier using Brunauer–Emmett–Teller (BET) and T-plot methods. On the basis of the computer analysis carried out and taking into account the results obtained, it has been shown that the material with the best adsorption properties and suitable for practical industrial applications is activated carbon obtained in a gaseous nitrogen atmosphere at an activation time of 30 min. Moreover, the value of the heterogeneity parameter indicates that the surface area of this activated carbon is homogeneous, which is of particular importance in the practical application. The paper emphasizes that an erroneous approach to the interpretation of analytical results based on gas adsorption isotherms, which consists in basing conclusions only on the values of a single parameter such as specific surface area or micropore volume, should be avoided. Therefore, it is recommended to use in the analysis of measurement data, several methods of porous structure analysis, including methods considering the heterogeneity of the surface, and when interpreting the results one should also take into account the adsorption process for which the analyzed materials are dedicated.


2019 ◽  
Vol 63 (2) ◽  
Author(s):  
Fariba Malekian ◽  
H. GHAFOURIAN ◽  
K. ZARE ◽  
A. A. SHARIF ◽  
Y. ZAMANI

Abstract. In this study, four different nanostructures precursors, pistachio wood, walnuts wood, forest wood and coal (Anthracite) were selected to produce activated carbon. The experiments were done in industrial scale using a rotary furnace with temperature between 850 and 920 ºC for 45 minutes followed by steam. The product was grounded and divided in three particle sizes, 8x30, 30x50, and 60x80 meshes. The physical properties and surface chemistry of the activated carbon samples were determined by imaging of BET-N2 adsorption. The results obtained from measurements of iodine and methylene blue numbers, surface area, pore volume and comparison of surface area and pore volume, show that by decreasing of particle sizes of each sample, increase the surface area and micro pore volumes significantly. The magnitude of changes in surface area with particle size is a significant factor in defining the effectiveness and suitability of an activated carbon for the production of carbon molecular sieve. Our results indicate that the highest pore volume belongs to pistachio wood, which was increased from 0.168 to 0.271 cm3/g from 8x30 to 60x80 mesh.                                         Resumen. En este estudio, se seleccionaron cuatro precursores de nanoestructuras diferentes, madera de pistache, madera de nueces, madera de bosque y carbón (antracita) para producir carbón activado. Los experimentos se realizaron a escala industrial utilizando un horno rotatorio con una temperatura entre 850 y 920 ºC durante 45 minutos, seguido de vapor. El producto se molió y se dividió en tres tamaños de partículas, en mallas de 8x30, 30x50 y 60x80. Las propiedades físicas y la química de la superficie de las muestras de carbón activado se determinaron mediante imágenes de la adsorción de BET-N2. Los resultados obtenidos de las mediciones de los números de yodo y azul de metileno, área de superficie, volumen de poros y comparación de área de superficie y volumen de poros muestran que, al disminuir los tamaños de partícula de cada muestra, aumenta significativamente el área de superficie y los volúmenes de microporos. La magnitud de los cambios en el área de la superficie con el tamaño de partícula es un factor significativo en la definición de la efectividad y la idoneidad de un carbón activado para la producción de tamiz molecular de carbono. Nuestros resultados indican que el mayor volumen de poros pertenece a la madera de pistache, que aumentó de la malla de 0.168 a 0.271 cm3/g de 8x30 a 60x80.


2021 ◽  
Vol 29 (3) ◽  
Author(s):  
Ekemini Monday Isokise ◽  
Abdul Halim Abdullah ◽  
Tan Yen Ping

In this work, activated carbons were produced by the thermochemical treatment of palm kernel shells with different activation time. The developed products (activated carbon samples) were described by their surface area, porosity, and applied for lead(II) ions separation from liquid phase. By prolonging the activation time beyond 2h, some of the micropores collapsed to form mesopores without causing a significant transformation in the surface area. The influences of solution pH, mass of biosorbents, concentration of Pb(II) ions, and temperature on the entrapment of lead(II) ions explored. Based on experimental outcome, the best-suited condition for the Pb(II) uptake was 0.13 g AC-4, 250 mg L-1 concentration, and pH 4. The Pb(II) entrapment process is thermodynamically exothermic and spontaneous. The adsorption data fit the Langmuir monolayer adsorption model, with 222 mg g-1 as maximum sorption capacity, and the Ho-second-order kinetics model suitably described the process rate.


Author(s):  
V. Sivanandan Achari ◽  
A. S. Rajalakshmi ◽  
S. Jayasree ◽  
Raichel Mary Lopez

In this study, a new series of coconut shell based granular activated carbons (GAC) are prepared by impregnating with zirconium ions as zirconyl chloride and activated under superheated steam. These carbons are designated with activation temperature/ conditions as GAC 383 (activated at 383K), GACO 383 (HNO3 oxidised), GACZR 1273 (ZrOCl2 activated at 1273K) and GACOZR 1273 (HNO3 oxidised, ZrOCl2 activated at 1273K). Surface characteristics of these carbons are evaluated using Boehm titration methods, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction techniques (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). The pore volume and the respective specific surface area of each carbon are determined by BET, I plot, Langmuir, Freundlich, and Dubinin-Radushkevich isotherms using N2 adsorption data at 77K. Analysis shows that zirconium ion enhances the surface area and porosity of granular activated carbon. The adsorption characteristics of newly prepared GAC are tested by solid-liquid equilibria using phenol as adsorbate. Equilibrium phenol adsorption data fitted to standard isotherm models of Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) equations. Adsorption constants and parameters indicate that zirconium impregnated granular activated carbons are relatively more efficient for the removal of phenol than the native carbon used.


Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2951
Author(s):  
Mirosław Kwiatkowski ◽  
Jarosław Serafin ◽  
Andy M. Booth ◽  
Beata Michalkiewicz

This paper presents the results of a computer analysis of the effect of activation process temperature on the development of the microporous structure of activated carbon derived from the leaves of common polypody (Polypodium vulgare) via chemical activation with phosphoric acid (H3PO4) at activation temperatures of 700, 800, and 900 °C. An unconventional approach to porous structure analysis, using the new numerical clustering-based adsorption analysis (LBET) method together with the implemented unique gas state equation, was used in this study. The LBET method is based on unique mathematical models that take into account, in addition to surface heterogeneity, the possibility of molecule clusters branching and the geometric and energy limitations of adsorbate cluster formation. It enabled us to determine a set of parameters comprehensively and reliably describing the porous structure of carbon material on the basis of the determined adsorption isotherm. Porous structure analyses using the LBET method were based on nitrogen (N2), carbon dioxide (CO2), and methane (CH4) adsorption isotherms determined for individual activated carbon. The analyses carried out showed the highest CO2 adsorption capacity for activated carbon obtained was at an activation temperature of 900 °C, a value only slightly higher than that obtained for activated carbon prepared at 700 °C, but the values of geometrical parameters determined for these activated carbons showed significant differences. The results of the analyses obtained with the LBET method were also compared with the results of iodine number analysis and the results obtained with the Brunauer–Emmett–Teller (BET), Dubinin–Radushkevich (DR), and quenched solid density functional theory (QSDFT) methods, demonstrating their complementarity.


Author(s):  
S. Manocha ◽  
Parth Joshi ◽  
Amit Brahmbhatt ◽  
Amiya Banerjee ◽  
Snehasis Sahoo ◽  
...  

In the present work, a one step carbon activation process was developed by stabilized poly-blend. It is carbonized in nitrogen atmosphere and activated in steam in one step for known interval of times to enhance the surface area and develop interconnected porosity. The weight-loss behavior during steam activation of stabilized poly-blend at different temperatures, surface area and pore size distribution were studied to identify the optimum synthesis parameters. The results of surface characteristics were compared with those of activated carbon prepared by carbonization and activation in two steps. It was found that activation temperature has profound effect on surface characteristics. As activation temperature was raised from 800 °C to 1150 °C, surface area of activated carbon increased about three times. In addition to surface area, average pore diameter also increases with increasing activation temperature. Thus, activated carbon with high percentage of porosity and surface area can be developed by controlling the activation temperature during activation process.


2013 ◽  
Vol 16 (1) ◽  
pp. 22-31
Author(s):  
Phung Thi Kim Le ◽  
Kien Anh Le

Agricultural wastes are considered to be a very important feedstock for activated carbon production as they are renewable sources and low cost materials. This study present the optimize conditions for preparation of durian peel activated carbon (DPAC) for removal of methylene blue (MB) from synthetic effluents. The effects of carbonization temperature (from 673K to 923K) and impregnation ratio (from 0.2 to 1.0) with potassium hydroxide KOH on the yield, surface area and the dye adsorbed capacity of the activated carbons were investigated. The dye removal capacity was evaluated with methylene blue. In comparison with the commercial grade carbons, the activated carbons from durian peel showed considerably higher surface area especially in the suitable temperate and impregnation ratio of activated carbon production. Methylene blue removal capacity appeared to be comparable to commercial products; it shows the potential of durian peel as a biomass source to produce adsorbents for waste water treatment and other application. Optimize condition for preparation of DPAC determined by using response surface methodology was at temperature 760 K and IR 1.0 which resulted the yield (51%), surface area (786 m2/g), and MB removal (172 mg/g).


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