p.5
Effects of Activation Parameters on Textural Properties
What is the significance of the KOH activation parameters?
They impact the textural properties of rCB/ACs.
p.5
Characterization Techniques for Activated Carbons
What was the primary objective of the SEM-EDS analysis?
To map the spatial distribution of potassium on the surfaces of rCB/ACs and quantitatively evaluate the surface elemental composition.
p.9
Mechanisms of rCB Activation by KOH
What process generates pores in the carbon matrix?
Carbon gasification in the presence of CO2.
p.9
Mechanisms of rCB Activation by KOH
What is the role of metallic potassium in the activation of rCB?
It intercalates into the carbon matrix and is mainly responsible for generating the pore network.
p.3
Chemical Composition and Structure of End-of-Life Tires (ELTs)
What is the principal component of rCB?
Carbon, ranging from 92% to 99.5 wt%.
p.2
Optimization of Activated Carbon Production from rCB
What is the sustainable approach for managing waste flows and producing value-added products?
The conversion of End-of-Life Tires (ELTs) into recovered Carbon Black (rCB) and Activated Carbons (ACs).
p.7
Effects of Activation Parameters on Textural Properties
What are the optimized values of S BET, V TOT, and V MIC for the rCB/KOH mass ratios studied?
S BET: 1025 m²/g, V TOT: 0.901 cm³/g, V MIC: 0.901 cm³/g.
p.10
Potassium-Based Activators in Carbon Activation
What factors influence the effectiveness of potassium-containing agents in generating pore structures?
Types and amounts of gases released, control over pore generation, and specific chemical reactivity under activation conditions.
p.2
Potassium-Based Activators in Carbon Activation
Which activation method is generally more favorable for producing Activated Carbons?
Chemical activation, due to lower temperature requirements and higher efficiency.
p.3
Comparison of Potassium Salts in Activation Processes
Which potassium salts were investigated for their synergistic role in rCB activation?
KCl, K2CO3, CH3COOK, and K2C2O4·H2O.
p.7
Effects of Activation Parameters on Textural Properties
What activation parameters influence the textural properties of rCB/ACs?
Temperature, mass ratio, activation time, and heating rate.
p.7
Effects of Activation Parameters on Textural Properties
What happens to the specific surface area of rCB/ACs when the temperature increases from 700 to 800 °C?
It increases to between 688 − 945 m²/g.
p.9
Mechanisms of rCB Activation by KOH
What evidence supports the breakdown of K2CO3 into K2O?
XRD patterns of rCB/ACs show the detection of K2O post-thermal treatment.
p.5
Characterization Techniques for Activated Carbons
What technique was used to analyze the distribution of potassium on recycled rCB/ACs?
Scanning electron microscopy with an energy-dispersive X-ray spectroscopy system.
p.9
Mechanisms of rCB Activation by KOH
What is the significance of the temperature range 800-900 °C in the context of K2CO3?
It is where K2CO3 decomposes into K2O and CO/CO2.
p.2
Chemical Composition and Structure of End-of-Life Tires (ELTs)
What are the primary carbon precursors for producing Activated Carbons?
Solid fossil fuels, biomass, and polymers with little ash content.
p.4
Characterization Techniques for Activated Carbons
What technique is used to examine the crystallographic structure of rCB/ACs?
X-ray diffraction analysis using a Bruker D8 Discover X-ray diffractometer.
p.2
Characterization Techniques for Activated Carbons
What physicochemical properties are important for Activated Carbons?
Large specific surface area, well-defined network of pores, significant mechanical strength, and abundant functional groups.
p.6
Effects of Activation Parameters on Textural Properties
What is the impact of heating rate on the textural properties of rCB/ACs?
It influences the BET surface area, total pore volume, and microporosity.
p.8
Mechanisms of rCB Activation by KOH
What happens to activation properties at a 1:4 KOH ratio?
There is a decrease in all properties compared to the 1:5 ratio.
p.10
Potassium-Based Activators in Carbon Activation
What can influence the temperature required for effective decomposition in the activation process?
The system can influence the overall process.
p.3
Characterization Techniques for Activated Carbons
What characterization techniques were used for the carbon materials?
X-ray diffraction (XRD) analysis and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS).
p.5
Effects of Activation Parameters on Textural Properties
What type of isotherm curves were analyzed in relation to the activation effects?
N2 adsorption-desorption isotherm curves at 77 K.
p.10
Characterization Techniques for Activated Carbons
What type of isotherm do all rCB/ACs share?
The same type of N2 isotherm as KOH, indicating uniform adsorption behavior.
p.4
Optimization of Activated Carbon Production from rCB
What is the base activation condition set in the study?
1:4 ratio, 800 °C, 3 hours, and 5 °C/min heating rate.
p.6
Potassium-Based Activators in Carbon Activation
How does KOH activation affect the pore characteristics of rCB?
It exhibits both micro- and mesoporous characteristics.
p.8
Effects of Activation Parameters on Textural Properties
What is the impact of heating rates below 7 °C/min?
They may improve contact between carbon and molten KOH before the desired reaction temperature is reached.
p.5
Characterization Techniques for Activated Carbons
What software was used for phase identification during activation?
DIFFRA-C.EVA software, with reference to the PDF-4 + 2022 database (ICDD).
p.3
Effects of Activation Parameters on Textural Properties
What factors of KOH activation were tested in the study?
Reaction phase, mass ratio, temperature, heating rate, and activation time.
p.4
Characterization Techniques for Activated Carbons
What does Q represent in the BET equation?
The mass of gas adsorbed at a given relative pressure.
p.10
Potassium-Based Activators in Carbon Activation
What is the order of effectiveness for the development of textural properties among potassium activators?
KOH > K2C2O4 > CH3COOK > K2CO3 > KCl.
p.7
Mechanisms of rCB Activation by KOH
What is the significance of KOH in the activation process?
It enhances porosity and increases the BET surface area of rCB/ACs.
p.10
Mechanisms of rCB Activation by KOH
What is the role of potassium ions and related anions in the activation process?
They serve as powerful activators of rCB/ACs and influence the formation of porous structures.
p.5
Effects of Activation Parameters on Textural Properties
What activation parameters were optimized in the study?
Temperature, mass ratio, activation time, and heating rate.
p.1
Effects of Activation Parameters on Textural Properties
What parameters were investigated in the KOH activation process?
KOH/rCB mass ratio, activation temperatures, activation time, and heating rate.
p.4
Characterization Techniques for Activated Carbons
How is the total pore volume (V_TOT) determined?
From the N2 adsorption isotherm at a high relative pressure, typically close to unity (0.99 or higher).
p.3
Mechanisms of rCB Activation by KOH
What is the impact of potassium interaction with rCB surface?
It can improve the production of activated carbons and promote sustainability by using waste materials.
p.1
Environmental Impact of End-of-Life Tires
What environmental issue is associated with the disposal of end-of-life tires?
They can release hazardous substances into soil and water systems during degradation.
p.4
Characterization Techniques for Activated Carbons
What is the significance of the coefficient of determination (R²) in the BET theory modification?
It indicates the highest linear relationship for the adsorption data.
p.2
Optimization of Activated Carbon Production from rCB
What is the effect of KOH on the specific surface area of Activated Carbons?
KOH activation can enhance specific surface area significantly, ranging from 180 to 820 m²/g.
p.9
Mechanisms of rCB Activation by KOH
What phases are formed during the multistage transformation involving K2CO3?
K2CO3, K2CO3·1.5H2O, and K4(CO3)3·(H2O)3.
p.9
Mechanisms of rCB Activation by KOH
How does humidity affect K2CO3?
It can undergo a hydration process, forming K2CO3·1.5H2O.
p.3
Characterization Techniques for Activated Carbons
How was the specific surface area of samples calculated?
Using experimental data fitted to the BET equation after N2 adsorption-desorption tests.
p.2
Effects of Activation Parameters on Textural Properties
What are the essential pretreatment techniques for carbon precursors?
Washing, drying, and thermal treatment.
p.3
Optimization of Activated Carbon Production from rCB
What are the key objectives of the research on rCB activation?
To reveal optimal conditions for rCB activation, establish responsible factors for conversion to ACs, and uncover the mechanism driving rCB activation.
p.10
Potassium-Based Activators in Carbon Activation
What is the significance of KHCO3 in the activation process?
Its formation is influenced by the partial pressure of CO2 and moisture content, and it can decompose into KOH and CO2.
p.3
Optimization of Activated Carbon Production from rCB
What was the baseline activation parameter determined for the study?
800 °C, 1:4 mass ratio, 3 hours, and 5 °C/min heating rate.
p.4
Characterization Techniques for Activated Carbons
What method is used to examine micropore volume (V_MIC)?
Density functional theory (DFT) approach, specifically the nonlocal density functional theory (NLDFT) model.
p.4
Optimization of Activated Carbon Production from rCB
What is the effect of KOH activation temperature on porosity development?
Different temperatures (700, 800, 900 °C) affect the porosity of rCB/ACs.
p.2
Mechanisms of rCB Activation by KOH
How does potassium affect the activation process of carbon?
It enhances activation kinetics and promotes the formation of a well-defined porous morphology.
p.3
Effects of Activation Parameters on Textural Properties
What is the significance of tailored activation parameters for different AC precursors?
They are essential for optimally developing porous structures and surface characteristics.
p.6
Chemical Composition and Structure of End-of-Life Tires (ELTs)
What type of pore system is indicated by the N2 isotherms of rCB/ACs?
A bimodal pore system consisting of both micropores and mesopores.
p.6
Characterization Techniques for Activated Carbons
What does the presence of significant N2 adsorption at P/P0 below 0.05 indicate?
The presence of micropores in the rCB/ACs.
p.1
Chemical Composition and Structure of End-of-Life Tires (ELTs)
What are the main components found in end-of-life tires?
Natural and synthetic rubber, fabric/fillers, accelerators, antiozonants, carbon black, and steel wire.
p.2
Effects of Activation Parameters on Textural Properties
What impact do activation parameters have on Activated Carbons?
They significantly influence the structure and characteristics of the resulting Activated Carbons.
p.8
Mechanisms of rCB Activation by KOH
What occurs at a KOH ratio of 1:6?
Diminishing returns with excess KOH, leading to potential pore blockage.
p.5
Role of Potassium and Functional Groups in Porosity Development
What is the role of potassium in the activation process?
To enhance the porosity development in rCB/ACs.
p.10
Potassium-Based Activators in Carbon Activation
Which potassium-containing salt exhibited the highest BET surface area among the samples?
K2C2O4_1:4_800_3 with a BET surface area of 299 m2/g.
p.6
Effects of Activation Parameters on Textural Properties
What is the significance of residence time, heating rate, and activation parameters in rCB precursor examination?
They are critical aspects for understanding the limitations of the rCB precursor.
p.4
Characterization Techniques for Activated Carbons
How is mesopore volume (V_MES) estimated?
By subtracting the micropore volume from the total pore volume.
p.2
Environmental Impact of End-of-Life Tires
Why are commercial Activated Carbons often costly?
They rely on nonrenewable precursors.
p.2
Comparison of Potassium Salts in Activation Processes
What are some common activating agents used in chemical activation?
Oxidizing acids, salt solutions, and alkalis such as KOH and NaOH.
p.1
Activation of Recovered Carbon Black (rCB)
What is the main focus of the study on recovered carbon black (rCB) from end-of-life tires (ELTs)?
The conversion of rCB into activated carbons (ACs) using potassium-based activators to enhance textural properties.
p.1
Optimization of Activated Carbon Production from rCB
What were the optimal conditions identified for the activation of rCB?
800 °C activation temperature, 7 °C/min heating rate, 1:5 KOH/rCB ratio, and 4 hours activation period.
p.1
Pyrolysis as a Method for Recycling ELTs
What is the significance of pyrolysis in the context of ELTs?
It is recognized as the most effective method for recycling ELTs, producing pyrolytic char rich in rCB.
p.8
Chemical Composition and Structure of End-of-Life Tires (ELTs)
What primary phases were identified in rCB/ACs during activation?
K2CO3, K2CO3·1.5H2O, K4(CO3)2·(H2O)3, KHCO3, and K2O.
p.7
Effects of Activation Parameters on Textural Properties
What occurs during the activation of rCB between 800 and 900 °C?
Formation of wide interconnected mesopores and partial degradation of specific area to 915 m²/g.
p.1
Mechanisms of rCB Activation by KOH
What role does KOH play in enhancing the textural properties of rCB?
It interacts with the graphite-like structure of rCB, primarily through K+ ions.
p.2
Chemical Composition and Structure of End-of-Life Tires (ELTs)
What are the main components of Activated Carbons?
Elemental carbon in an amorphous state and fine-crystalline graphite.
p.8
Mechanisms of rCB Activation by KOH
What is the effect of a 1:3 KOH ratio on activation?
It indicates insufficient activation.
p.6
Characterization Techniques for Activated Carbons
According to IUPAC classification, what types of isotherms do the curves of rCB/ACs exhibit?
A mixture of type I and type IV isotherms.
p.6
Characterization Techniques for Activated Carbons
What type of hysteresis loop is observed in the desorption isotherm of rCB/ACs?
An H3-type hysteresis loop, indicating slit-shaped pores.
p.8
Mechanisms of rCB Activation by KOH
What is the significance of the rCB structure in KOH activation?
Its closed nature restricts potassium accessibility, hindering penetration and reactions.
p.2
Mechanisms of rCB Activation by KOH
What gap exists in current research regarding K-containing agents?
Limited understanding of how K-containing agents interact with char carbon atoms and other activation factors.
