On the preparation and characterization of chars and activated carbons from orange skin
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Potassium hydroxide
Potassium hydroxide
Phosphoric acid
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In this work, we selected potassium hydroxide (KOH) as a chemical agent for acetic acid (CH3COOH) removal and loaded KOH on activated carbon. We considered the influence of KOH-loading on the specific surface area, the pore volume and the removal ability of CHsh3COOH in order to use KOH loaded activated carbon as air purifier filters. The KOH-loading of activated carbon proportionally increases with increasing the concentration of KOH aqueous solution, while the specific surface area and the pore volume show decreasing trends with the increase of KOH-loading. We find that KOH is easily loaded in the micropores smaller than 1nm and loaded on the surface region of activated carbon as well as in the larger pores with increasing KOH-loading. The deodorization performance of KOH loaded activated carbon as purifier filters was also evaluated using Tobacco. Activated carbon with the higher KOH-loading shows a shorter removal time of CH3COOH and has an ability of treating the larger number of tobacco, while the rate of increase of the number of tobacco which activated carbon can treat is small compared with that of KOH-loading increase.
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In this work activated carbon has been prepared from different agricultural sources. The process of preparing activated carbon was conducted through carbonization the raw material at 350° C for 3 hrs. The carbonized product were subjected to final step of carbonization by mixing the feed stoke with potassium hydroxide (1:1) (raw materials: KOH) at 550±25° C for 3 hrs. The carbon obtained was purified by disttiled water, refluxed with 10 % hydro chloric acid for 2hrs, washed with disttled water and finally dried at 110-120° C for 24 hrs. The activated carbon obtained was evaluated by measuring (Iodine number, methylene blue, humidity content, ash content and Density) and Compared with commercial carbon from B. D. H.
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The effect of pressure, temperature, microporous size of activated carbon on adsorption process of isopro-pyl alcohol on activated carbon was studied by Grand Canonical Monte Carlo Simulation. The result shows that the adsorption process can be described reliably by the activated carbon microporous model. When the pressure is 1kPa, the adsorption quantity of activated carbon with microporous size of 1. 7nm is higher. While activated carbon with microporous size of 2. 0nm has higher adsorption quantity when the pressure is 2-4kPa. At the pressure of 4 -10kPa, the adsorption quantity of activated carbon with microporous size of 2. 5nm is higher. The adsorption quantity of the system which jaws width of activity carbon is 2. 5nm is higher. The best recovery temperature of iso-propyl alcohol desorbed from activated carbon is 140℃.
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Abstract This manuscript investigates the influence of the chemical activation step order and process parameters on the specific capacitance of activated carbon derived from rice husk. The chemical activation was performed either before or after the carbonization step, using phosphoric acid (H 3 PO 4 ) and potassium hydroxide (KOH) as activating agents. For activation before carbonization, the carbonization process was conducted at various temperatures (600, 750, 850, and 1050 °C). On the other hand, for activation after carbonization, the effect of the volume of the chemical agent solution was studied, with 0, 6, 18, 21, 24, and 30 mL/g of phosphoric acid and 0, 18, 30, 45, 60, and 90 mL/g of 3.0 M KOH solution. The results revealed that in the case of chemical activation before carbonization, the optimum temperature for maximizing specific capacitance was determined to be 900 °C. Conversely, in the case of chemical activation after carbonization, the optimal volumes of the chemical agent solutions were found to be 30 mL/g for phosphoric acid (H 3 PO 4 ) and 21 mL/g for potassium hydroxide (KOH). Moreover, it was observed that utilizing phosphoric acid treatment before the carbonization step leads to an 21% increase in specific capacitance, attributed to the retention of inorganic compounds, particularly silica (SiO 2 ). Conversely, when rice husks were treated with KOH after the carbonization step, the specific capacitance was found to be doubled compared to treatment with KOH prior to the carbonization step due to embedding of SiO 2 and KHCO 3 inorganic constituents. This study provides valuable insights into the optimization of the chemical activation step order and process parameters for enhanced specific capacitance in rice husk-derived activated carbon. These findings contribute to the development of high-performance supercapacitors using rice husk as a sustainable and cost-effective precursor material.
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The activated carbons were prepared from coking fly ash with steam activation and potassium hydroxide as the activating agents,respectively.The iodine sorption values,BET specific surface areas,pore size distributions,pore volumes and surface morphologies of the obtained samples had been characterized.The results show that the adsorption performance of activated carbon activated by potassium hydroxide is better than those made by steam.The obtained activated carbon activated by potassium hydroxide was of mesopore type with a BET specific surface area of 275.51 m2/g.
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Abstract A hierarchical microporous carbon material with a Brunauer–Emmett–Teller surface area of 1348 m 2 g −1 and a pore volume of 0.67 cm 3 g −1 was prepared from yeast through chemical activation with potassium hydroxide. This type of material contains large numbers of nitrogen‐containing groups (nitrogen content >5.3 wt %), and, consequently, basic sites. As a result, this material shows a faster adsorption rate and a higher adsorption capacity of CO 2 than the material obtained by directly carbonizing yeast under the same conditions. The difference is more pronounced in the presence of N 2 or H 2 O, showing that chemical activation of discarded yeast with potassium hydroxide could afford high‐performance microporous carbon materials for the capture of CO 2 .
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Using viscose fiber (VF) as starting material and common steam as activating agent, formation of oxygen structures in activated carbon fiber is investigated. In the preparation of samples, VF was first heated at temperatures between 450℃ and 900℃ in N2 artmosphere. Then, in a successive activation stage, the product carbonized at 600℃ was activated in steam at 450 - 900℃ for 30 min, and at 600℃for 5- 30 min. The other carbonization products were activated at 600 and 900℃ for 30 min respectively. The products activated at 900℃ were then activated at 450℃ for 30 min again. The starting material, carbonized products and all activation products were examined by FT-IR spectroscopy and some products were examined by X-ray photoelectron spectroscope (XPS). And the yields of the carbonized and activated products were calculated. By analysing these spectra, the amount of oxygen-containing functional groups of the activated products attained under various activation time, various activation temperature and various previous carbonization temperature was determined.
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CF4 is a gas with high global warming potential and has an extremely long atmospheric lifetime. This study developed a method for capturing CF4 gas via adsorption using microporous carbons. Microporous carbon adsorbents were synthesized by a facile protocol involving carbonization of poly(vinylidene fluoride) (PVDF) at high temperatures (400–800 °C) without additional activation, and the effects of carbonization on the characteristics and CF4 adsorption of PVDF-based adsorbents were investigated. Increasing the carbonization temperature enhanced the textural properties of the adsorbent, resulting in the increased CF4 adsorption capacity. Above 700 °C, PVDF was fully dehydrofluorinated, and the microporous carbon synthesized at 800 °C exhibited superior textural properties with a maximum CF4 adsorption capacity of 1.85 mol/kg at 25 °C under atmospheric pressure. The PVDF-based microporous carbons also exhibited fast adsorption–desorption kinetics, excellent cyclic stability, and good selectivity for CF4 over N2 at relatively low CF4 pressures. The microporous carbons developed in this study have potential for use as novel adsorbents for CF4 capture.
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Activated carbons are prepared from hemp stem with KOH as activating agent under different ratio of KOH to carbon conditions. The BET(Brunauer Emmett and Teller) specific surface area of the hemp stem-based activated carbons first increases and then decreases with the increasing ratio of KOH to carbon. The specific surface area, micropore surface area and volume of the activated carbons reach a maximum of 1589.27m 2 /g 1420.52m 2 /g, 89% of the total area, 0.751m 3 /g at the ratio of 4.5:1. The micropore size distribution shows the activated carbons contain a large number of ultramicropore and supermicropore.
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