Effects of vacuum pyrolysis conditions on the characteristics of activated carbons derived from pistachio-nut shells (original) (raw)
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Characteristics of activated carbons prepared from pistachio-nut shells by physical activation
Journal of Colloid and Interface Science, 2003
The regulating of a structure and a pores volume of activated carbons by mechanical, chemical and thermal activations of agricultural wastes, such as apricot kernel shells were studied. The mechanical activation was provided in the grinding mill, in the aqueous medium. The chemical activation was implemented by treatment with sulfuric, hydrochloric, phosphoric acids at the concentrations of 5%-40% and by zinc chloride at the penetration coefficients of 0.1÷0.6. The thermal activation was effected in carbon dioxide atmosphere at the temperatures of 300÷100 о С. It was researched an influence of acid concentration, ZnCl 2 coefficient of impregnating, CO 2 temperature per volume of micro-, meso-and macropores. Activated carbons have arranged porous structures in the following line: processed by ZnCl 2 and CO 2 > processed by ZnCl 2 > processed by H 2 SO 4 > processed by H 3 PO 4. For the samples are treated by ZnCl 2 and subsequent CO 2 , the activation optimal parameters are following: temperature of CO 2 =500 о С; the penetration coefficient = 0.4.
Preparation of Activated Carbons from Macadamia Nut Shell and Coconut Shell by Air Activation
Industrial & Engineering Chemistry Research, 1999
A novel, three-step process for the production of high-quality activated carbons from macadamia nut shell and coconut shell charcoals is described. In this process the charcoal is (i) heated to a high temperature ("carbonized"), (ii) oxidized in air following a stepwise heating program from low (ca. 450 K) to high (ca. 660 K) temperatures ("oxygenated"), and (iii) heated again in an inert environment to a high temperature ("activated"). By use of this procedure, activated carbons with surface areas greater than 1000 m 2 /g are manufactured with an overall yield of 15% (based on the dry shell feed). Removal of carbon mass by the development of mesopores and macropores is largely responsible for increases in the surface area of the carbons above 600 m 2 /g. Thus, the surface area per gram of activated carbon can be represented by an inverse function of the yield for burnoffs between 15 and 60%. These findings are supported by mass-transfer calculations and pore-size distribution measurements. A kinetic model for gasification of carbon by oxygen, which provides for an Eley-Rideal type reaction of a surface oxide with oxygen in air, fits the measured gasification rates reasonably well over the temperature range of 550-660 K.
Energy Fuels, 2007
Use of waste as raw material for producing porous carbon was investigated in this work. Physic nut (Jatropha curcas L.) residue from oil extraction for biodiesel production was pyrolyzed at 400-800°C with hold times of 15, 120, and 240 min to obtain char precursors. Activated carbon, with favorable Brunauer-Emmett-Teller surface area in a narrow range, was prepared by soaking these chars in concentrated KOH, H 3 PO 4 , as well as a pure CO 2 gas flash activator. The maximum specific surface area of 532.30 m 2 g-1 was developed for the alkaline-treated sample. The carbon fraction of activated materials was as much as 90 wt %, significantly higher than the char precursor. Mesopore of 2-50 nm and total pore volumes of the materials were also significantly enhanced by these activations. Nitrogen adsorption isotherms of physic-nut-waste-activated carbons indicated that they were mainly mesopores. Pores of char activated by KOH and H 3 PO 4 are irregular, of different shapes and sizes, and the macropores seemed to be connected to mesopores, especially for the KOHactivated case. Surface analysis of pyrolyzed and activated char using Fourier transform infrared spectroscopy indicated main functional groups that are considerably different to those of activated materials, which may lead to greater adsorption potential of activated samples. However, functional groups on each activated carbon are quite similar even with different activation processes. According to the data obtained, physic nut residue pyrolyzed at 800°C and followed by KOH activation could be used as a low-cost adsorbent with favorable surface properties.
Chemical Engineering Journal, 2011
Activated carbons having high surface area were produced from pistachio shells that were chemically activated using zinc chloride at room temperature and then activated in carbon dioxide gas that was saturated in water vapor. The surface area and pore structure of activated carbon produced from pistachio shells were investigated depending on the amount of chemical activating reagent, activation temperature, duration time in the reagent solution and the kinds of activation reagent. In this study, a method, which provides activated carbons having the highest surface area was developed. As a result, the activated carbon produced from pistachio shells treating with 40% ZnCl 2 then with 40% HCl in room temperature and then activated at 900 • C for 90 min has 3256 m 2 /g of BET surface area and 3822 m 2 /g of DR surface area and 1.36 cc/g of DR micropore volume. It was found that the activated carbon produced from pistachio shells treated 40% of sodium chloride and activated at 900 • C for 90 min has 3895 m 2 /g of BET surface area and 5235 m 2 /g of DR surface area and 1.86 cc/g of DR micropore volume.
Journal of Chemistry, 2015
In this study, raw hazelnut shells were used to obtain charcoal by pyrolysis at 250°C. The obtained material was subjected to physical, chemical, and physicochemical treatment methods to obtain activated carbons (ACs). Effect of the treatment procedures was determined by measuring the surface area of the produced ACs. In addition, changes in the functional groups of the obtained ACs during these treatments were determined with the Fourier transform infrared spectroscopy (FT-IR). To determine the most effective chemical agent, the charcoal samples were examined for Pb(II) adsorption from aqueous solutions under different pH conditions of 4 to 6. According to the results, the most effective chemical agent was determined as Ca(OCl)2. Effect of microwave and ultrasound treatments was also examined during Pb(II) adsorption by the chemically treated AC. The results showed that chemical treatment with Ca(OCl)2, microwave treatment for 5 minutes, ultrasound treatment for 20 minutes, and pyr...
Activated carbons were prepared from Fox nutshell by chemical activation with H 3 PO 4 in N 2 atmosphere and their characteristics were studied. The effects of activation temperature and impregnation ratio were examined. N 2 adsorption isotherms characterized the surface area, total pore volume, micropore volume and pore size distribution of activated carbons. Activated carbon was produced at 700 °C with a 1.5 impregnation ratio and one hour of activation time has found 2636 m 2 /g and 1.53 cm 3 /g of highest BET surface area and total pore volume, respectively. The result of Fourier-infrared spectroscopy analysis of the prepared activated carbon confirmed that the carbon has abundant functional groups on the surface. Field emission scanning electron micrographs of the prepared activated carbon showed that a porous structure formed during activation.
Highly active carbons on base of biomass waste - nut shells
19th International Scientific Conference Engineering for Rural Development Proceedings, 2020
The research is devoted to obtaining of highly porous activated carbons from apricot stones and pistachio, hazelnut, walnut shells from various regions using thermocatalytic activation with sodium hydroxide. Influence of the raw material properties and origin, as well as the precursor to activator ratio on a porous structure was studied. It was found that at activation temperature 700 ºC and NaOH to carbonizate ration 2:1 and 3:1 a highly developed porous structure is being formed, which can be controlled altering meso-and micropores volumes. It is demonstrated that the highest porosity was achieved in the case of walnut shells and apricot stones, and the obtained materials can be used for sorption and as electrodes in supercapacitors, fuel cells and Li-ion batteries
Investigation of Pyrolyzed Chars from Physic Nut Waste for the Preparation of Activated Carbon
Journal of Solid Mechanics and Materials Engineering, 2007
Fixed bed pyrolysis of physic nut waste was conducted to investigate the influence of different operating conditions, such as sample size, final temperature and hold time, on properties of the pyrolyzed chars. The obtained chars were characterized by a thermogravimetric analyzer (TGA) for proximate analyses and by Brunauer-Emmett-Teller (BET) for determination of their accelerated surface area. The surface morphology of char was investigated using scanning electron microscopy (SEM). For chemical characterization, an X-ray diffractometer (XRD) and a Fourier transform infrared spectroscope (FTIR) were used to identify inorganic components and surface organic functional groups of the char. In this work, the FTIR analysis indicated the existence of phosphonate groups, carboxyl groups and amine groups on char surface. The XRD pattern of the surface also verified the presence of graphite as main carbon structure. The conditions yielding char with maximum BET surface area of 249.60 m 2 •g-1 and high fixed carbon are final temperature of 800°C, hold time of 15 minutes, and heating rate of 20°C/min for 0.425-0.5 mm particle. Generally, high temperature pyrolysis of raw materials with short hold time results in char with favorable smooth, porous surface with large cavities.
Pore structure of activated carbon prepared from hazelnut bagasse by chemical activation
Surface and Interface Analysis, 2008
In this study, hazelnut extracted-bagasse which is a waste from oil factory was used for the production of activated carbon by chemical activation using ZnCl 2 and KOH as activating agents. Hazelnut bagasse has been impregnated with aqueous solutions of ZnCl 2 and KOH in the ratio of 1-3 g agent per g precursor. The carbonization treatment was performed at 500, 600 and 700 • C for 2 h under nitrogen flow. The surface area, pore volumes, pore size distribution and average pore diameter of the activated carbons were characterized by N 2 adsorption at 77 K using the BET, t-plot and DFT methods. The highest surface areas of activated carbons are 1642 and 1489 m 2 /g and total pore volumes are 0.964 and 0.9329 cm 3 g −1 for KOH and ZnCl 2 , respectively. The surface chemical characteristics of activated carbon were determined in terms of surface functional groups. These groups were analyzed by Fourier transform infrared (FTIR) spectroscopic method and Boehm's titration method. Surface morphology was investigated by SEM. According to the results, activated carbons prepared from hazelnut bagasse by chemical activation have high surface area and porosity.
Developing almond shell-derived activated carbons as CO2 adsorbents
Separation and Purification Technology, 2010
Two series of carbon dioxide adsorbents were prepared from almond shells, by carbonisation followed either by activation with CO 2 or by heat treatment in the presence of ammonia gas (amination). Both procedures gave carbons with high CO 2 adsorption capacities in pure CO 2 as well as in a binary mixture of 15 % CO 2 in N 2 .