scholarly journals Temperature Dependent Characteristics of Activated Carbons from Walnut Shells for Improved Supercapacitor Performance

2018 ◽  
Vol 20 (2) ◽  
pp. 99 ◽  
Author(s):  
V.V. Pavlenko ◽  
Q. Abbas ◽  
P. Przygocki ◽  
T. Kon’kova ◽  
Zh. Supiyeva ◽  
...  
Keyword(s):  
Activated Carbons ◽  
Electrochemical Techniques ◽  
Electrochemical Capacitor ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Activation Temperature ◽  
Walnut Shells ◽  
Bet Specific Surface Area ◽  
Capacitive Properties ◽  
Supercapacitor Performance

Activated carbons (ACs) have been prepared from chemical treatment of walnut shells (WS) precursor at various temperatures (400‒800 °C) by using phosphoric acid (H3PO4) as activating agent. Influence of activation temperature on the porosity development and capacitive properties of resulting carbons was investigated. Thermal post-treatment of carbons previously activated at moderate temperature, e.g. 400 °C allowed further structural and porosity modification. Then, these carbons were investigated by scanning electron microscopy, Raman spectroscopy, energy-dispersive X-ray spectroscopy, electrochemical techniques and low temperature nitrogen adsorption exhibiting high BET specific surface area of approximately 2100 m2 g-1 and a total pore volume up to 1.3 cm3 g-1. Carbon material obtained through activation by H3PO4 at 400 °C and post-treated at 800 °C was used to make electrodes which were implemented to realize AC/AC capacitor using 1 mol L-1 Li2SO4. The electrochemical capacitor demonstrated high capacitance of 123 F g-1 per mass of one electrode, reduced cell resistance and stable capacitance for 5000 galvanostatic charge/discharge cycles at 1.0 A g-1.

Optimization of Production Conditions for Activated Carbons from Rice Husk by Potassium Carbonate Using Response Surface Methodology

2014 ◽  
Vol 1053 ◽  
pp. 303-310 ◽  
Author(s):  
Mian Wu Meng ◽  
Cong Liang Qi ◽  
Qing Ye Liu ◽  
Liang Lv ◽  
Hao Ai ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Adsorption Capacity ◽  
Response Surface ◽  
Rice Husk ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Average Pore ◽  
Activation Temperature ◽  
Nitrogen Adsorption Isotherm

A three-factor-three-level experiment was developed by the central composite design (CCD) and Response surface methodology to discuss the effects of concentration of K2CO3, activation temperature and time on the adsorption capacity of the activated carbon (AC) derived from the rice husk and to identify the key preparation parameters. The performance of the AC was characterized by nitrogen adsorption isotherm as Brunauer–Emmett–Teller (BET) and scanning electron microscope (SEM), respectively. The optimal parameters were obtained: Rice husk was soaked in K2CO3 solution (2.32 mol/L) with an impregnation ratio (rice husk: K2CO3=1:3) (wt. %), activated at 1239 K for 0.48 h. The results showed that iodine adsorption capacity of the AC was 1268.52 mg/g, the error between the models predicted (1356.98 mg/g) was only 6.2%. The AC has a large apparent surface area (SBET = 1312 m2/g), total pore volume (0.78 cm3/g) and average pore diameter (11.92 Å).

Wood-based activated carbons for supercapacitors with organic electrolyte

Holzforschung ◽  
2015 ◽  
Vol 69 (6) ◽  
pp. 777-784 ◽  
Author(s):  
Galina Dobele ◽  
Aleksandrs Volperts ◽  
Galina Telysheva ◽  
Aivars Zhurinsh ◽  
Daria Vervikishko ◽  
...  
Keyword(s):  
Activated Carbons ◽  
Specific Capacity ◽  
Total Pore Volume ◽  
Synthesis Temperature ◽  
Raw Material ◽  
Organic Electrolyte ◽  
Electrochemical Characteristics ◽  
Activation Temperature ◽  
Synthesis Conditions ◽  
Ohmic Losses

Abstract The thermocatalytical synthesis conditions required for the activation of wood charcoal with NaOH in terms of the formation of pores in its structure were investigated. The present study was conducted to explore the potential application of activated carbons as electrodes in supercapacitors with organic electrolyte. The total pore volume and micro- and mesopore ratio were controlled by the activation temperature and alkali addition rate. The working characteristics of carbon electrodes (e.g., specific capacity and ohmic losses) in supercapacitors are strongly influenced by the properties of the pores in their structures. Herein, the optimal ratio of raw material to activator and activation temperature are established: an increase in the ratio of NaOH to carbonizate rate by a factor of 2 and setting the synthesis temperature at 700°C positively influence the electrochemical characteristics of supercapacitors and provide them with specific capacities of up to 160 F g-1.

scholarly journals Characterization and comparison of walnut shells-based activated carbons and their adsorptive properties

2020 ◽  
Vol 38 (9-10) ◽  
pp. 450-463
Author(s):  
Xiya Li ◽  
Jieqiong Qiu ◽  
Yiqi Hu ◽  
Xiaoyuan Ren ◽  
Lu He ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Activated Carbons ◽  
Low Cost ◽  
Total Pore Volume ◽  
Textural Properties ◽  
Hydrothermal Carbonization ◽  
Bet Surface Area ◽  
Activation Process ◽  
Walnut Shells ◽  
Adsorption Desorption

The production of low-cost biologically activated carbons (BACs) is urgent need of environmental protection and ecological sustainability. Hence, walnut shells were treated by traditional pyrolysis, direct KOH impregnation and combined activation composed of hydrothermal carbonization and two-step H3PO4- and pyrolysis-activation process to obtain porous carbon with high adsorption capacity. It was found that the best adsorption capacity for iodine and organic dye methylene blue (MB) can be obtained using the KOH impregnation at impregnation ratio of 1:1 or combined activation comprising of 2 h H3PO4 activation and 1 h pyrolysis activation at 1000°C. The produced KOH, H3PO4/pyrolysis activated BACs at the optimum conditions are superior to that of commercial ACs, 9.4 and 1.3 times for MB removal, 4 and 4.5 times for iodine number respectively. Characterization results demonstrated their porous structure with very good textural properties such as high BET surface area (1689.1 m2/g, 1545.3 m2/g) and high total pore volume (0.94 cm3/g, 0.96 cm3/g). The N2 adsorption-desorption isotherm of H3PO4/pyrolysis activated hydrochar suggested the co-existence of micro and meso-pores. Moreover, they are more effective for the removal of Fe(III) and Cr(VI) from aqueous solution than the commercial AC, suggesting a promising application in the field of water treatment.

Preparation of activated carbons from wet activated sludge by direct chemical activation

2009 ◽  
Vol 59 (12) ◽  
pp. 2387-2394 ◽  
Author(s):  
X. Wang ◽  
N. Zhu ◽  
J. Xu ◽  
B. Yin
Keyword(s):  
Activated Carbon ◽  
Activated Sludge ◽  
Water Content ◽  
Iodine Value ◽  
Activated Carbons ◽  
Chemical Activation ◽  
Total Pore Volume ◽  
Processing Parameters ◽  
Experimental Conditions ◽  
Activation Temperature

An improved method for preparing activated carbons from wet waste activated sludge (WAS) by direct chemical activation was studied in this paper. The effects of processing parameters on iodine adsorption capacity of the product were investigated. Results show that sludge-based activated carbon prepared with KOH had a larger iodine value than those activated with ZnCl2 and KCl. The maximum iodine value was observed at the KOH concentration of 0.50 M. Increasing the impregnation time from 10 to 20 h resulted in a 20% increase in the iodine value. The highest iodine value was obtained at the activation temperature of 600°C and holding time of 1 h. Sludge water content had insignificant effects on the iodine value of products. Raw WAS with a water content of 93.2% can be converted into an activated carbon with a high specific surface area of 737.6 m2 g−1 and iodine value of 864.8 mgg−1 under optimum experimental conditions. Other physical properties such as total pore volume, micropore volume and mean pore diameter of the product were also reported and compared with those of commercial activated carbon.

Characterization of Rambutan Seed (Nephelium lappaceum) as Natural Adsorbent for Wastewater Treatment

2013 ◽  
Vol 701 ◽  
pp. 408-411
Author(s):  
Norlia Mohamad Ibrahim ◽  
Siti Fatimah Zahra Mohd Sarif ◽  
Roshazita Che Amat ◽  
Shamshinar Salehuddin ◽  
Nur Liza Rahim
Keyword(s):  
Zinc Chloride ◽  
Activated Carbons ◽  
Total Pore Volume ◽  
Carbonization Temperature ◽  
Bet Surface Area ◽  
Nitrogen Gas ◽  
Activation Temperature ◽  
Nephelium Lappaceum ◽  
Two Factors

Activated carbons were prepared from rambutan seed with impregnation of zinc chloride as dehydrating agent. In order to find its characteristics, different zinc chloride to rambutan seed ratio (0.5 and 2) and activation temperature (450 and 650 °C) was employed. The carbonization occurred in a tube furnace with flow of nitrogen gas at 0.5 L/min. The results showed that at higher impregnation ratio and carbonization temperature produced a wider BET surface area of activated carbon that was 9.8761 m2/g. Total pore volume also increased with increases of these two factors. However activation yield was decreased with increasing of carbonization temperature.

scholarly journals Preparation and characterization of bio-based activated carbon from fish scales

BioResources ◽  
2020 ◽  
Vol 16 (1) ◽  
pp. 614-621
Author(s):  
Qingsong Ji ◽  
Haichao Li ◽  
Jingjing Zhang
Keyword(s):  
Activated Carbon ◽  
Functional Groups ◽  
Photoelectron Spectroscopy ◽  
Activated Carbons ◽  
Structural Characteristics ◽  
Total Pore Volume ◽  
Bet Surface Area ◽  
Fish Scales ◽  
Average Pore ◽  
Activation Temperature

The object of this study was to prepare activated carbons containing nitrogenous functional groups by a chemical method from nitrogen-containing raw materials. Fish (Ctenopharyngodon idellus) scales were impregnated with phosphoric acid (H3PO4) and activated at varied temperatures. The adsorption ability, structural characteristics, surface chemistry, and morphology of the activated carbons were characterized by methylene blue and iodine values, nitrogen adsorption, the Boehm method, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The total alkaline groups content of the activated carbon produced from fish scales was 0.4330 mmol/g, the total acidic groups was 1.68 mmol/g, the Brunauer–Emmett–Teller (BET) surface area was 501 cm2/g, and the total pore volume was 0.284 cm3/g. The average pore diameter was 1.94 nm under an activation temperature of 550 °C, an activation time of 1 h, and an impregnation ratio of 2. As a result of this study, nitrogenous functional groups that contained acid-base amphoteric adsorbent were produced.

scholarly journals ADSORPTION OF 4-CHLORPHENOL BY BROWN COAL ACTIVATED BY POTASSIUM HYDROXIDE

2021 ◽  
Vol 29 (1) ◽  
pp. 36-48
Author(s):  
Yuliia Tamarkina ◽  
Volodymyr Kucherenko ◽  
Iryna Frolova
Keyword(s):  
Adsorption Capacity ◽  
Surface Area ◽  
Brown Coal ◽  
Activated Carbons ◽  
Linear Equations ◽  
Specific Capacity ◽  
Total Pore Volume ◽  
Koh Activation ◽  
Activation Temperature ◽  
Alkaline Activation

The purpose of work is to evaluate the 4-chlorophenol (CP) adsorption capacity of brown coal activated carbons (ACs) prepared at different temperature of KOH activation. ACs were obtained in three stages: 1) impregnation of coal with a KOH solution, 2) heating (4 deg/min) in argon to a given temperature t (400-800°C) and exposure for 1 h, 3) cooling, washing from KOH, drying. The samples are designated as AC(t). Based on the N2 adsorption-desorption isotherms, the ACs total pore volume (Vt, cm3/g) and specific surface area (S, m2/g) were determined. The ACs adsorption capacity were measured at 25°С, CP concentration ≤700 mg/L, АC dosage – 1 g/L. The alkaline activation temperature was found to be a key factor in forming porosity of ACs and ability to adsorb CP. The CP maximum capacity (ACP(m), mg/g) increases 6.6 times up to 307 mg/g for AC(800) having S=1142 m2/g. The specific adsorption capacity (ACP(S) = ACP(m)/S, mg/m2) sharply decreases in a sample range from AC(400) to AC(550) and weakly depends on temperature at 550-800°C. The kinetics of CP adsorption is best described by a pseudo-second order model. The rate determining stage is the interaction of CP molecules with AC surface. The CP adsorption isotherms are best described by the Langmuir model. The dependence of the ACP(m) from S can be approximated by three linear equations that probably correspond to the three regions of forming surface adsorbtion centers (AdCs). The first (S≤370 m2/g) is characterized by a small adsorption capacity increment (kS=0.103 mg/m2), but a significant (16.4 times) decrease in the specific capacity ACP(S). In the second region (S=370-770 m2/g, t=550-750°C), capacity increment is 10 times more (kS=0.985 mg/m2) and in the third region (S≥770 m2/g, t≥750°C) the increase in CP capacity is the smallest (kS=0.067 mg/m2). The thermoinitiated formation of AdCs is assumed to be not proportional to the increase in surface area, and their chemical structure and reactivity is determined by the alkaline activation temperature.

scholarly journals Preparation of Activated Carbon from the Biodegradable film for Co2 Capture Applications

2018 ◽  
Vol 20 (3) ◽  
pp. 75-80
Author(s):  
J. Serafin ◽  
A.K. Antosik ◽  
K. Wilpiszewska ◽  
Z. Czech
Keyword(s):  
Activated Carbon ◽  
Activated Carbons ◽  
Low Cost ◽  
Chemical Activation ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Waste Utilization ◽  
Co2 Production ◽  
Biodegradable Film ◽  
Adsorption Desorption

Abstract In this work for the fi rst time, activated carbons were prepared from carboxymethyl fi lm (low-cost carboxymethyl fi lm waste), using chemical activation with potassium hydroxide. The samples were characterized by nitrogen adsorption-desorption at 77 K, XRD, SEM methods. The high values of the specifi c surface area and total pore volume were achieved and were equal to 2064 m2/g and 1.188 cm3/g, respectively. Waste from the fi lm can be immediately utilized without CO2 production. This is the environmentally friendly way of waste utilization. Through this process, we can protect our environment. This study showed that the activated carbon obtained from carboxymethyl fi lm waste can be used as a good adsorbent for CO2 adsorption.

scholarly journals Influence of alkaline activation temperature on the porous structure of the activated brown coal and its capacity to adsorb phenol

2021 ◽  
pp. 132-138
Keyword(s):  
Brown Coal ◽  
Activated Carbons ◽  
Physical Adsorption ◽  
Nitrogen Adsorption ◽  
Adsorptive Capacity ◽  
Activation Temperature ◽  
Phenol Adsorption ◽  
Alkaline Activation ◽  
Equilibrium Concentrations ◽  
Adsorption Desorption

The purpose of this work was to evaluate the influence of alkaline activation temperature (t) on the pore structure of activated carbons produced from brown coal (ACs) and their adsorption capacity towards the sorption of phenol from aqueous solutions. The ACs were prepared by heating (t=400–8500C, 1 hr) of brown coal impregnated with KOH; the prepared samples were designated as AC(t). Based on the nitrogen adsorption-desorption isotherms (77 K), the total volume and surface (S) of all pores and separately micro- and subnanopores were determined. Maximum phenol adsorption capacities of ACs (Am) were registered at the temperature of 250С. The activation temperature was stated to be the most significant factor influencing the ACs capacity to adsorb phenol. The growth of temperature from 4000С to 8500С in the case of AC(800) results in an exponential increase in the value of Аm from 27 mg g–1 to 240 mg g–1 (a maximal value) according to the following equation: Аm=6.038exp(0.0045t) (R2=0.952). The kinetics of phenol adsorption obeys the second order model (R20.982). The AC(800) adsorption isotherm is described by the Freundlich equation (R2=0.988) within the equilibrium concentrations Ce=0.001–2.5 mg cm–3 with the heterogeneity factor nF=3.23 indicating physical adsorption. The same model for Ce0.001 mg cm–3 (R2=0.951) gives nF=0.52, which suggests chemical adsorption. The specific adsorptive capacity АS=Аm/S sharply decreases from 2.11 mg m–2 to 0.21 mg m–2 with increasing the temperature from 4000С to 5500С and remains constant (0.200.01 mg m–2) for ACs prepared at higher temperatures. The invariability of AS indicates the temperature independence of adsorption centers concentrations of ACs prepared within 550–8500С.

scholarly journals Adsorption of Carbon Dioxide onto Activated Carbon Prepared from Coconut Shells

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Pei-Hsing Huang ◽  
Hao-Hsiang Cheng ◽  
Sheau-Horng Lin
Keyword(s):  
Activated Carbon ◽  
Pore Volume ◽  
Ph Value ◽  
Total Pore Volume ◽  
Ash Content ◽  
Activation Time ◽  
Activation Temperature ◽  
Bet Specific Surface Area ◽  
Iodine Adsorption ◽  
Coconut Shells

This study presents the fabrication of high-quality activated carbon (AC) from discarded coconut shells. The effects of experimental parameters such as activation temperature and activation time on the basic characteristics of AC, including charcoal yield, ash content, pH value, Brunauer-Emmett-Teller (BET) specific surface area, total pore volume, and iodine adsorption, are investigated. The results indicate that as the activation temperature and activation time increase, the charcoal yield of the AC decreases. In contrast, iodine adsorption, ash content, pH value, and total pore volume increase with activation temperature. The AC sample activated at 1000°C for 120 min had the highest BET specific surface area and total pore volume and thus the best CO2adsorption performance. This sample was compared with 30-mesh commercial AC. The results reveal that coconut-based AC has better instantaneous adsorption capabilities.

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