Influence Of Activation Temperature Research Articles

Tailoring tea residue-derived nitrogen-doped activated carbon for CO2 adsorption: influence of activation temperature and activating agents.

Embracing CO2 mitigation strategies, such as state-of-the-art CO2 capture technologies, is essential for effectively reducing atmospheric carbon levels and advancing global efforts toward a more sustainable future. In this context, adsorption sequestering techniques utilising carbon materials have emerged as promising candidates for CO2 capture. These materials have been extensively researched with a range of tuning methods to optimise their physicochemical features. In this study, an alteration of the N-doped activated carbon was successfully performed, utilizing tea residue as the carbon precursor and ammonia as the nitrogen source, facilitated through an impregnation procedure. With the objective of discovering the effect of diverse activation parameters on prepared adsorbent physicochemical properties, several selections of activating agents (AA) were investigated: KOH, H3PO4, ZnCl2, and NaOH, together with broad thermal activation temperature from 873 to 1173K. The best-performed adsorbents from the respective AC group were subjected to several characterisation analyses and found to the enhanced structural features, heteroatom doped-rich surface (i.e. N and O); together with AA-induced metal/mineral functionalization, the NaOH-used AC (NAC-N-1173) was the optimum-performed adsorbent with a promising 4.12mmol/g CO2 uptake capacity, higher than other prepared adsorbent including N-doped tea residue-derived char and commercialized AC with 175 and 325% higher, respectively.

Synthesis of Cr(VI)-adsorbed carbon from Artocarpus heterophyllus peel waste: activated conditions, characterizations and adsorption isotherm

Lignocellulosic biomass is often activated with phosphoric acid to make value-added goods. However, statistical effects of impregnation ratio (IR) and activation temperature (AT) on Artocarpus heterophyllus peel-derived activated carbon have not been studied. This study used an experimental approach and regression model to investigate these impacts on Cr(VI) adsorption capacity. A regression model and analysis of variance assessed these two factors’ variation. The activated carbon’s morphology, surface functional groups, and Cr(VI) adsorption isotherm at optimal conditions were examined using Brunauer, Emmett and Teller, X-ray diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectrometry, Boehm titration, pH drift methods, Langmuir, and Freundlich models. The quadratic regression model described the influence of AT and IR on Cr(VI) adsorption capacity and found the best values of 545°C and 4:1. When IR and AT ranged from 1.89 to 4.0 and 330°C to 545°C respectively, the combined effect caused the most variance and had a synergistic effect on Cr(VI) adsorption capacity. This activated carbon at optimal conditions had many carboxylic groups, a porous, amorphous surface, and a maximum mono-layer capacity of 29.498 mg g-1. Freundlich is a better Cr(VI) adsorption model. This study will give a technical way and advocate for the utilization of activated carbon derived from Artocarpus heterophyllus peel as an effective material for the removal of chromium (VI) from water.

Influence of activation temperature and prestress on behavior of Fe-SMA bonded joints

The prestressed strengthening of structures via use of bonded iron-based shape memory alloys (Fe-SMAs) has proven promising, albeit with concerns regarding the temperature dependency of the adhesive properties. In this study, the effect of activation temperature and generated prestress are investigated experimentally. Six Fe-SMA-to-steel adhesively bonded joints, comprising different Fe-SMA strips (non-prestrained and prestrained) and activation strategies (full activation and partial activation), were prepared, activated via electrical resistance heating, and tested under quasi-static loading. It is found that the bond–slip behavior of a joint with activation can be modeled by that of an equivalent non-activated joint. The generated prestress influences the full-range behavior by raising the base tensile stress level of the Fe-SMA strip, with negligible effects on further aspects of the full-range behavior. With the increasing activation temperature, the fracture energy is initially increased and eventually reduced, while the bond capacity and effective bond length are retained almost constant.

Introducing an active opening strategy to mitigate large open-plan compartment fire development

‘Travelling fire’ behaviour was found in large compartment fire tests with initial window openings, which exhibits slow fire development benefiting fire safety design and firefighting. Since much faster fire spread is found in the same compartment with glass panels, this paper attempts to explore an ‘active opening’ strategy to open the glass panels to regain the ventilation assumptions. The proposed strategy uses an activation temperature to control the opening and it has been now implemented in the CFD fire models. Two extreme situations, i.e., initial opening without glass and windows initially closed with glass, are investigated. A striking difference of fire behaviour is found as flashover is observed in the latter scenario compared to the localized burning in the former case. While implementing active opening, the influences of activation temperature and window height on the performance of mitigating fire development are investigated. It is found that a lower activation temperature allows faster removal of hot smoke and thus avoids spontaneous ignition. Furthermore, the effect of window height is demonstrated as higher opening reduces the thickness of hot smoke, which effectively enables lower floor radiation and thus mitigates fast fire spread.

Preparation of flotation refined carbon from gasification slag

Highly efficient and environmentally friendly utilization of coal gasification slag is a hot research subject in the coal chemical industry at present. The preparation of activated carbon with a flotation refined carbon from gasification slag, a long flame coal, a high temperature coal tar containing 70% asphalt and an active agent in proper proportion was carried out. The influence of activation temperature and time on the surface properties and compressive strength of the produced activated carbon was investigated in a tube furnace. The oxygen functional group, pore structure and absorption performance of the produced activated carbon were characterized by FT-IR, N2 adsorption-desorption, SEM and iodine adsorption. The COD removal from biochemical waste water by the produced activated carbon was verified. The results show that the key factors for the effective formation and expansion of pore are the suitable activation temperature and time for the floatation refined carbon from gasification slag as the feedstock. The activated carbon prepared by carbonization at 550 °C for 30 min and steam activation at 950 °C for 2 h exhibits a crisscross morphology of organic carbon components and minerals. The surface area, pore capacity and average pore diameter are 566 m2/g, 0.5611 mL/g and 5.1 nm, respectively, with the characteristics of a concentrated pore distribution and a certain quantity of mesopore. Both iodine value (650 mg/g) and methylene blue value (128 mg/g) meet the requirements of the Chinese standard “Technical Specifications and Test Methods of Activated Carbon for Purification of Industrial Wastewater”. The COD in biochemical waste water treated by the activated carbon for 60 min with a solid-to-liquid ratio of 0.6 g/L can be reduced to lower than 30 mg/L, meeting the B class water quality of the Chinese standard “Integrated Discharge Standard of Water Pollutants” (DB11/307—2013).

The Performance of Chitosan-based Activated Carbon for Supercapacitor Applications towards Sustainable Energy Technologies

In sustainable technologies, the application of supercapacitors (SC) for energy conversion and storage systems is rapidly increasing. Supercapacitors are widely employed in applications that require fast charge and discharge phases, such as in the automobile industry, where they are utilized in energy storage. Chitosan (CS) is a natural polymer material utilized in supercapacitor fabrication. Interest in supercapacitors is due to their high-energy capacity, storage for a shorter period, and longer lifetime. In this research, the fabrication of symmetric supercapacitors with activated carbon (AC) electrodes has been investigated in order to analyze their performance characteristics. AC is derived from CS biomass, which has remarkable biodegradability. It has been chemically activated using ZnCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> as the activating agent. CS has been activated inside a furnace at 500, 600, and 700°C in an inert N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> atmosphere. A 1M aqueous potassium hydroxide (KOH) solution is used as the electrolyte. The test using electrolytes (KOH) revealed that the electrode's specific capacitance was 74.7 Fg <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , the highest value discovered. However, using organic electrolytes would have produced better results that can be used as a guide for future advancements. The influence of activation temperature on the porous characteristics of prepared AC was investigated utilizing surface area and pore size analyses. The morphological characteristics of synthesized AC were analyzed through scanning electron microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX). Symmetric SC electrodes fabricated is analyzed in a two-electrode system applying standard electrochemical characterization methods using the potentiostat. Symmetric SC electrodes fabricated are analyzed in a two-electrode system applying standard electrochemical characterization methods using the potentiostat.

Effects of Preparation and Activation Manner on Surface Area of Hierarchical Porous Carbons Derived from Nut (Euryale ferox) Shell

AbstractHierarchical nano‐micro carbon spheres porous carbon composites are successfully synthesized derived from Euryale ferox shells by the in‐situ decoration of the porous carbon with carbon spheres from carboxymethyl cellulose under the activation of KOH. Effects of fabrication and activation manner on surface area of porous carbons were investigated. The influence of activation temperature, impregnation ratio and modifier were analyzed. The specific surface area, pore volume and average pore diameter of porous carbon was characterized by N2 adsorption isotherms. Porous carbon produced at 800 °C with an impregnation ratio of 3, 2 hours of carbonization time, 20 hours immersion time has been found 2506 m2 g−1, 1.515 cm3 g−1 and 2.4 nm of the optimum specific surface area, pore volume and average pore diameter, respectively. The result of Fourier‐infrared spectroscopy analysis of the prepared porous carbon confirmed that it has abundant functional groups on the surface. The scanning electron micrographs of the prepared porous carbon indicated that a well‐developed pore structure was formed during the experiment.

Management of surgical mask waste to activated carbons for CO2 capture

The worldwide COVID-19 pandemic has resulted in a huge amount of face masks being used up and thrown away, resulting in increased environmental pollution and infection risks. In our work, we have developed a highly efficient process of neutralizing face mask waste into a useful carbon material. Then, the prepared activated carbon was used for CO2 adsorption studies. A series of activated carbons from face masks used as a precursor were synthesized using KOH and the activation temperature was in the range of 600–800 °C. All materials were characterized by well-developed porosity. The influence of activation temperature on the textural properties of prepared activated carbons and their adsorption abilities were investigated. The highest CO2 adsorption was received for the M_800 carbon and it was 3.91 mmol/g at the temperature of 0 °C and the pressure of 1 bar. M_800 carbon exhibited also high selectivity of CO2 over N2. Seven equilibrium isotherms were applied to the experimental data to find out the best fit (Langmuir, Freundlich, Sips, Toth, Unilan, Fritz-Schlunder and Radke-Prausnitz isotherms). The presented research provides an environmentally friendly and cost-effective method of recycling waste masks into a valuable product in the form of carbon and its potential use in the absorption of harmful CO2 influencing the greenhouse effect.

The Influence of Activation Temperature on the Structure of Hierarchical Porous Carbon Materials Prepared from Coal Tar Pitch and Their Performance as Supercapacitor Electrodes

The Influence of Activation Temperature on the Structure of Hierarchical Porous Carbon Materials Prepared from Coal Tar Pitch and Their Performance as Supercapacitor Electrodes

Preparation of fly ash-based flocculant and flocculation performance

Using fly ash from a thermal power plant in Yingkou City as raw material, The inorganic polymer flocculant polyaluminum ferric chloride (PAFC) was prepared by sodium carbonate impregnation, high temperature roasting activation, and acid leaching. The influence of activation temperature and activation time on the leaching of aluminum and iron was investigated through single factor test and orthogonal test. The PAFC preparation conditions were optimized, and the prepared PAFC flocculant product was applied to kaolin turbidity water. The test results showed that the content of aluminum in fly ash was 7.08%, and the content of iron was 4.95%. The mass ratio of the activator sodium carbonate and fly ash was 10:7, the activation temperature was 800°C, and the activation time was 2h. The leaching rates of aluminum and iron were the highest, 88.31% and 53.66% respectively. The optimal conditions for the preparation of the flocculant were as follows: the molar ratio of aluminum to iron was 5.7:1, and the reaction time was 1.5h. The liquid product obtained under these conditions was yellowish brown, and the solid product obtained after being dried was yellow powder.

Cadmium adsorption by thermal-activated sepiolite: Application to in-situ remediation of artificially contaminated soil

Soils contamination with Cd result in detriment to the environmental quality. In-situ immobilization methods by applying clay minerals have been gaining prominence. The effects on sepiolite of thermal activation at different temperatures (300–750 °C), for removing Cd from aqueous solutions were evaluated, in order to consider their further application for soil remediation. The influence of activation temperature was investigated using XRD, SEM, and N2 adsorption-desorption measurements. The S-600 exhibited the maximum adsorption capacity (21.28 mg/g), despite its lower SSA, and Langmuir model described the adsorption isotherms better than the Freundlich equation. TCLP was used to quantify the remediation effects of thermal-activated sepiolite on simulated soils artificially polluted with Cd. The results indicated that the mobility of Cd in soil was effectively reduced after treating with thermal-activated sepiolite and the use of S-600 was the most efficient, reducing the TCLP-Cd by approximately 73% compared with the control test. The main remediation mechanism was considered as the cation exchange of Cd by Mg at the edges of octahedral sheet. This study showed that thermal-activated sepiolite could be promising amendments for remediation of Cd-contaminated soil.

Turning waste into treasure: biomass carbon derived from sunflower seed husks used as anode for lithium-ion batteries

In this paper, sunflower seed husks were used as raw materials to prepare porous biomass carbon through physical carbonization and chemical activation. Calcium chloride and pyromellitic acid were used as activators and processing assistant. The influences of activation temperature and processing additives on the activation mechanism of CaCl2 were analyzed. The results showed that activation temperature and processing aids act on the two competing mechanisms of micropore formation and pore expansion, respectively. The average pore diameter of the resulting sample was 9.75 nm, and the specific surface area was 404.215 m2 g−1. The sample was circulated 100 cycles at 0.2 C. The specific flow was 1100 mAh g−1 in the change rate test. The discharge specific capacity was 590 mAh g−1 after 450 cycles at 2 C rate. The structure of the sample collapsed after 250 cycles at 5 C, and the specific discharge capacity dropped to 390 mAh g−1 after 350 cycles.

Effect of polyvinyl alcohol on the physico-chemical properties of soil and soil-amino acid interaction

Thin layer chromatography (TLC) is considered as an efficient analytical technique used for the monitoring and identification of the adsorption behaviour of different amino acids through soil as a stationary phase amended with polyvinyl acetate at different concentration. The study gives complete idea about the mobility of four different uncharged amino acids namely glycine, alanine, tryptophan and glutamine in terms of retention factor by thin layer chromatography. Among four amino acids, highest mobility was found in case of glycine. The order of mobility was found to be in order of glycine > alanine > tryptophan > glutamine in which distilled water has been used as a mobile phase. It has been observed from the results that pH and electrical conductivity also influence mobility of amino acids. The influence of activation temperature and particle size of soil on the mobility of amino acids was also studied.

Quantitative study of the oxidation state of iron-based catalysts by inverse temperature-programmed reduction and its consequences for catalyst activation and performance in Fischer-Tropsch reaction

Iron-based catalysts are frequently used in the Fischer-Tropsch reaction (FTR). The catalyst undergoes several phase changes during activation and catalytic reaction. Therefore, the activation and reduction conditions are crucial for the overall activity of the catalyst.The reduction of hematite with hydrogen was investigated by inverse temperature programmed reduction. Reduction proceeds either via the sequence Fe2O3 → Fe3O4 → α-Fe or, above 570 °C, via Fe2O3 → Fe3O4 → FeO → α-Fe. A quantitative approach for the individual reduction steps was proposed. Combining temperature ramps and isothermal ranges, the phase composition was investigated and correlated with catalytic results in the initial phase of FTR. For this, a hematite precursor was activated at different temperatures and applied as a catalyst for the FTR. An influence of activation temperature on the water gas shift activity and chain length of the formed hydrocarbons was observed. The formation of carbon dioxide as a product of the water gas shift reaction, was correlated with the presence of magnetite. Interestingly, hematite treated at temperatures below the temperature at which the formation of magnetite was expected, was already active in the FTR.

Preparation and water vapor adsorption of “green” walnut-shell activated carbon by CO2 physical activation

In this study, activated carbons without any chemical residue were prepared from walnut shells. The preparation method in a tube furnace included a pyrolysis carbonization process and a CO2 activation process. The influences of activation temperature and holding time on the specific surface area, yield, and pore structure were investigated. Adsorption performance of water vapor was also examined in details. Thermogravimetric analysis, N2 adsorption–desorption isotherm, and scanning electron microscope were used to characterize samples. The result shows that the activation energy at different heating rates varies from 30.16 to 64.86 kJ/mol. The highest water vapor adsorption capacity of the sample is 0.3824 g/g and it takes only 30 min to realize regeneration. And the maximum Brunauer–Emmett–Teller specific surface area of 1228 m2/g also occurs in this optimal preparation condition. CO2 physical activation method was found to have a positive effect on pore structure development of activated carbon for water vapor adsorption.

Influence of activation temperature and acid concentration on sludge-based activated carbon

In this work, the influence of operational parameters on activation process of POME sludge is presented. The POME sludge undergone processing steps including cutting and grinding. Then, the sample was carbonized at 400°C for 1 hours and followed by chemical activation process. The chemical activation process was carried out by impregnated with 25 wt% of phosphoric acid with impregnation ratios of 1:4 (w/w) for 24 h. After 24 h, the sample was filtrated and dried overnight in the oven. The sample then pyrolyzed at different temperature (500°C to 800°C) for 1 hour for activation and followed by washing. Based on the BET analysis, the activated carbon prepared under highest activation temperature as well as highest phosphoric acid concentration resulted in biggest surface area (186.46 m2/g). Therefore, activation temperature and acid concentration are the important parameters determining the activated carbon quality.

Performance of chitosan derived activated carbon in supercapacitor

In the present work, the performance characteristics of symmetric supercapacitor employing activated carbon electrodes have been studied in pure ionic liquid (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, EMITFSI) and its gel polymer. Activated carbon (AC) was derived from chitosan using chemical activation method. The influence of activation temperature on the porous characteristics of prepared AC was comprehensively investigated, employing surface area and pore size analyzer. Other textural properties of synthesized AC were investigated employing the techniques of scanning electron microscopy (SEM), x-ray diffraction (XRD) and Raman spectroscopy. Gel polymer electrolyte (GPE) was prepared employing solution cast method. Symmetric supercapacitor cells were prepared and their performance was evaluated in two-electrode system employing standard electrochemical characterization techniques. It was observed that the supercapacitor cell using GPE offers superior performance (in the context of specific capacitance and cyclic stability), as compared to the supercapacitor cell employing pure ionic liquid (IL).

Preparation of coffee-shell activated carbon and its application for water vapor adsorption

Coffee-shell activated carbon was prepared by a two-step activation method including carbonization process and potassium hydroxide (KOH) activation process. The influences of activation temperature, activation time and mass ratio of KOH to char on activated carbon water vapor adsorption performance were investigated by single factor design. The optimum preparation conditions of activated carbon with large adsorption capacity were determined. The water vapor adsorption experiments of activated carbon were carried out under 70% relative humidity and adsorption temperature of 298 K. Pore structure characteristics were studied via N2 adsorption-desorption isotherm. The results show that the optimum preparation conditions are activation temperature of 1073 K, activation time of 10 min and mass ratio of KOH to char of 3:1. The Brunauer–Emmett–Teller (BET) specific surface area, total pore volume and water vapor adsorption capacity of the optimum coffee-shell activated carbon are 2349 m2/g, 1.036 cm3/g and 0.7409 g/g, respectively. All isotherms are type I with narrow pore size distributions in micropore region. Moreover, the obtained activated carbon was characterized by pH, elemental analysis and Fourier transform Infrared (FT-IR) spectroscopy. The results show that the obtained activated carbon would be one of the potential adsorbents for dehumidification in solar energy drying system.

Preparation and Characterization of Shiitake Mushroom-Based Activated Carbon with High Adsorption Capacity

The potential of utilizing shiitake mushroom as feed stock for the preparation of activated carbon by chemical activation method with $$\text {K}_{2}\text {CO}_{3}$$ was explored. The prepared materials were characterized by thermogravimetric analysis, $$\text {N}_{2}$$ adsorption–desorption analysis, scanning electron microscope, Fourier transform infrared spectrometer, X-ray diffraction and Raman spectra. The activation mechanisms were proposed with the aid of thermogravimetric analysis. X-ray diffraction and Raman analysis indicated that the activated carbon was amorphous macroscopically. The influences of activation temperature, mass ratio of $$\text {K}_{2}\text {CO}_{3}$$ /shiitake mushroom, activation duration, heating rate and material mixed mode on the yield, porosity and surface morphology of the activated carbon were investigated in detail. The synthesized activated carbons was predominantly microporous having a specific surface area of 2330 m $$^{2}$$ /g, and the optimal process conditions were activation temperature of 800 $$^{\circ }$$ C, mass ratio of $$\text {K}_{2}\text {CO}_{3}$$ /shiitake mushroom of 1.5, activation duration of 180 min, heating rate of 5 $$^{\circ }$$ C/min and mixed mode of impregnation. Addition to high surface area, it also exhibited a high iodine number adsorption capacity of 1432 mg/g and methylene blue adsorption capacity of 872 mg/g, which are far higher than the adsorption capacities reported in the open literature. These results demonstrate that the synthesized activated carbon could be utilized for variety of industrial applications.

X-ray photoelectron spectroscopy analysis of chemically modified halloysite

The influence of activation temperature on the structure of halloysite mineral (HM) from the “Dunino” strip mine (Poland), activated with 25 wt% sulfuric(VI) acid, was investigated using a surface sensitive X-ray photoelectron spectroscopy (XPS) method. XPS measurements were performed for commercially available halloysite nanoclay (HNT), raw halloysite mineral (HS) directly from the mine and samples of a halloysite mineral (HM) activated at different temperatures up to 100 °C. The XPS spectra were measured in wide range of the electron binding energy (survey spectra) and in the region of O, Al and Si photoelectron peaks (detailed spectra). Changes of photoelectron peak positions and their intensities are discussed as a function of activation temperature. Elemental composition of HS, HM and HNT surfaces was estimated and compared with bulk results obtained using the wavelength dispersive X-ray fluorescence (WDXRF) method. Concentration changes of O, Al, Si and Fe obtained by both XPS and WDXRF measurements are discussed. An increase of the silicon to aluminum ratio (Si/Al), as a result of higher activation temperature, is demonstrated.