Activated Carbon Samples Research Articles

Adsorption of Sulfonamide Antibiotic onto Activated Carbon Prepared from an Agro-industrial By-Product as Low-Cost Adsorbent: Equilibrium, Thermodynamic, and Kinetic Studies

Olive pomace (OP) is an agricultural by-product of the olive oil production process. Olive oil mills generate a huge amount of OP that has adverse impacts on the environment due to its phytotoxic properties. Therefore, the utilization of OP in the production of activated carbon may be considered as an alternative eco-friendly solution for disposal and recycling of this waste. The adsorption of sulfadiazine (SDZ), an antibiotic of the sulfonamide group, using activated carbon from olive pomace (OPAC) was investigated under different experimental conditions. The characterization of synthesized activated carbon samples was performed by elemental analysis, BET surface area, total pore volume, average pore size, pHpzc, FTIR, and SEM-EDX analysis. In batch experiments, the effects of adsorption parameters such as pH of the solution, contact time, activated carbon dosage, initial SDZ concentration, and temperature were assessed. The results showed that the pH of the solution slightly affected the SDZ adsorption capacity of OPAC. In order to express the adsorption behavior of SDZ onto OPAC, Langmuir, Freundlich, Dubinin–Radushkevich (D–R), and Temkin isotherm models were applied to the experimental equilibrium data. The maximum adsorption capacity calculated from the Langmuir isotherm was 66.2252 mg/g at 298 K. The data from kinetic studies were analyzed using pseudo-first-order and pseudo-second-order models. The results indicated that the adsorption process of SDZ onto OPAC followed the pseudo-second-order model rather than the pseudo-first-order model. Based on the thermodynamic parameters including ΔG0, ∆H0, and ∆S0, it can be concluded that the nature of the adsorption process is exothermic, spontaneous, and favorable and of increased disorder and randomness. This work demonstrates that OP can be used as a precursor for activated carbon production and may substitute with commercial activated carbon for the removal of antibiotics from aqueous media. The production of activated carbon from OP will provide both minimization and recovery of this waste.

Effect of Wood Species on the Pore Volume and Surface Area of Activated Carbon Derived from the Self Activation Process

In this study, the effect of wood species on pore structure of activated carbon (AC) generated from a self-activation process at different dwelling times was investigated. Ten hardwood species were selected (afromosia, alder, black cherry, makore, pomelle sapele, soft maple, teak, walnut, white oak and yellow poplar) were activated at 1050OC for three dwelling times (10 h, 5 h, and 2.5 h). X-ray diffraction, Raman spectroscopy, and elemental analysis were performed on AC to analyze the carbon structure. The Brunauer-Emmett-Teller (BET) surface area, Barrett-Joyner-Halenda (BJH) pore volume, and BJH pore width of AC samples were determined. It was shown from the study that the mesopore width of AC decreased as micropores were transitioned to mesopores, leading to an increase in the pore volume and surface area. The density and porosity of the samples that underwent 2.5-h dwelling time were determined. The porosity of the wood and their resultant AC were compared. The porosity between the wood and its AC possessed a relationship when true bulk densities of the wood and carbon were compared. The porosity of wood had an impact on the bulk density of the carbon but not on the true density. No relationship was observed between the porosity and surface area of the carbon samples.

Synthesis of activated carbon from high-carbon coal fly ash and its hydrogen storage application

Activated carbons (ACs) have desirable characteristics that make them attractive for many industrial applications. In order to reduce their production cost, there is always a need to find alternative low-cost feedstock precursors. Nowadays zero-waste technologies play an important role in sustainable development, therefore using of coal by-product as source of AC is strongly recommended. In this study, coal fly ash (CFA) sample with a high unburned carbon content was used to synthesize ACs. The effect of acid pre-treatment of the CFA sample using HF and HCl prior to thermochemical activation using KOH was also investigated. The acid washing was found to be effective since it removed most of the inorganic components found in the CFA, as was confirmed by EDS and XRF. The resulting carbon-rich feedstock had relatively high content of meso-/macropores as well as with relative increase in specific surface area (46.19 m2/g - 81.20 m2/g). The obtained AC sample was found to exhibit high specific surface (946.77 m2/g) that was dominated by high microporosity and was tested for hydrogen storage. The H2 uptake (1 bar, 77 K) was found to be 1.35 wt% and with a predictable potential for even higher capacity when measurements are conducted at high pressures.

An efficient and sulfur resistant K-modified activated carbon for SCR denitrification compared with acid- and Cu-modified activated carbon

In this work and for the first time, an alkali metal potassium (K) as a promoter was loaded on an activated carbon (AC) to be used for selective catalytic reduction of NO from industrial flue gas. The denitrification activity of K-modified AC samples was investigated and compared with those of acid- and Cu-modified AC samples. The three modifications can enhance the denitrification activity of AC samples. To investigate the enhanced mechanisms of denitrification and SO2 resistance, various AC samples were characterized by SEM, EDX, XRF, ICP, XRD, N2 physisorption, H2-TPR, XPS, in situ DRIFTS and TPD. For the acid modification, the content of phenolic hydroxyl increases and then promotes the adsorption of NH3. For the loading of Cu, the appearance of Cu2+/Cu+ sites with high catalytic activity promotes NH3 and NO adsorption and changes the reaction pathway. For the loading of K, the adsorption capacity for NO increases nearly 12 times higher than that on Raw-AC, of which 85.0% is chemical adsorption. Moreover, three kinds of active nitrate species additionally forms, including nitro compounds, monodentate nitrate and nitrous oxide, which promote the denitrification reaction path. AC-Cu has poor sulfur resistance due to the sulfation of Cu, while AC-K show good sulfur resistance due to the enhanced adsorption of NO. The catalytic dissociation activity of N2O on AC-K makes the formation and decomposition of N2O into a dynamic equilibrium. As a result, AC-K has a high N2 selectivity, while AC-Cu has poor N2 selectivity.

Sulfonated activated carbons as potential catalysts for biolubricant synthesis

In this study, sulfonated activated carbons have been prepared, under different conditions, with the purpose of evaluating the effect of the nature and amount of sulfonic surface groups on the esterification reaction of free fatty acids (FFA) with different long-chain alcohols. The synthesized catalysts were characterized using different techniques and 1H NMR was used for monitoring the reaction products. The modifications of the surface functionalities were assessed by X-ray Photoelectron Spectroscopy (XPS) and Thermogravimetric analysis (TGA), while changes in the porous network and morphology of the samples were evaluated before and after the treatment of the original activated carbon sample. XPS results showed the presence of two types of sulfur, one from thiophenic sulfur (present on all materials, including the unmodified sample), and the other from sulfonic groups (SO3H), at 168 eV (present only in the modified samples). These catalysts were applied in the esterification reaction and presented excellent catalytic performances, while the original activated carbon exhibited conversions similar to reactions without any catalyst. On the other hand, the conversion of fatty acids when using the modified carbons improves significantly with values up to ∼100 % to mono alcohols and 70 % to trimethylolpropane.

Surface oxidized and un-oxidized activated carbon derived from Ziziphus jujube Stem, and its application in removal of Cd(II) and Pb(II) from aqueous media

Agricultural waste based low cost oxidized activated carbon (OSD) and un-oxidized activated carbon (USD) samples were prepared from saw dust of Ziziphus jujube by chemical activation with phosphoric acid (H3PO4). The activated carbon was used for the removal of toxic metal ions such as cadmium(II) and lead(II) from aqueous solutions. The effect of pH (2–9), initial concentration (70–100 mg/L), contact time (5–700 min), activated carbon dose (0.1–1.0 g) and temperature (298–328 K) was investigated. In addition, the kinetic study was performed at pH 6, while the carbon dose of 0.1 g was used for 40 mL solution of 70 mg/L at four different temperatures (298, 308, 318 and 328 K). The adsorption efficiency of USD was found higher than OSD. Comparatively higher uptake of Pb(II) ions was observed by each carbon sample. Pseudo-second order equation best fitted the experimental data. As such, both activated carbon samples (USD and OSD) exhibited higher adsorption capacities and faster kinetics which revealed their commercial usefulness.

Production of a carbonaceous sorbent from the CO2 pyrolysis of hydraulic fracturing flowback and produced water solids

Hydraulic fracturing produces wastewater, referred to as flowback and produced water, which can be saline or brackish, and contain residual additives (e.g.: friction reducers, biocides) and chemicals from the formation water (brines) that may pose risks to the environment, if not properly managed and handled according to existing regulations. Here, we created a pyrolyzed product from flowback water and characterize the resulting material for the purpose of using it for contaminant sorption. The produced pyrolyzed flowback water solids were compositionally comparable to biochar and activated carbon samples, had a high pH value (9.6), surface area (92 m2/g), and sorption capacity (120 mg/g methylene blue), and showed relatively low concentrations of most metals and metalloids as compared to other charcoal materials. The new material was shown to perform better than activated carbon and biochar to remove metals from flowback water, demonstrating its potential use in flowback water treatment operations.

Preparation and characterization of black liquor-derived activated carbon by self-chemical activation

A highly functional, environmentally friendly carbonaceous adsorbent material using black liquor (a by-product from the pulp manufacturing) was produced and characterized. This study showed the effect of self-chemical activation driven by inherent alkali, originated from the unique composition of black liquor. A preparation of the micropore-dominant activated carbon was made in an easy and simple manner. The specific surface areas of samples were found to be 718–1591 m2/g variated upon heat treatment conditions. The sample activated at 850 °C (50 min as retention time) showed the maximum specific surface area of 1591 m2/g with 13.6% as a production yield. Considering the factors influencing pore structure of activated carbon materials in this study, it was confirmed that mesopore-related surface area increased gradually as the activation temperature and retention time increased. It is noteworthy to address that economically valuable micropore-dominant activated carbon can be produced by a simple heat treatment of the waste material, black liquor. The activated carbon sample derived from black liquor can be applied to various fields, such as environment and energy storage.

A benchmark for CO2 uptake onto newly synthesized biomass-derived activated carbons

To properly address the threat of global warming, there is an urgent need to reduce CO2 from the atmosphere through the development of environment-friendly technologies. Therefore, capturing/storage and utilization of CO2 as a refrigerant for adsorption cooling/heating technologies have been gaining momentum in the last decades. This study focuses on the development of novel activated carbons (ACs) with extremely large pore volume and high surface area from environment-friendly and abundantly available biomass precursor seeking higher CO2 adsorption capacity. Four AC samples are synthesized from the two biomass precursor’s namely waste palm trunk (WPT) and mangrove (M) employing potassium hydroxide as an activating agent. The porous properties of the synthesized ACs are investigated from the N2 adsorption/desorption data. It is praiseworthy to elucidate that the highest surface area and pore volume for biomass-derived ACs (BACs) are obtained 2927 m2 g−1 and 2.87 cm3 g−1, respectively. CO2 adsorption characteristics are investigated using a high precision magnetic suspension balance unit at five different temperatures ranging from 25 to 70 °C with various pressures. The WPT-AC (C500)/CO2 pair shows the highest adsorption uptake as high as 1.791 g g−1 (excess adsorption) and 2.172 g g−1 (absolute adsorption) at 25 °C and 5.04 MPa, which is superior to any other ACs reported to date. To the best of our knowledge, porous properties and adsorption uptake of CO2 reported in this study are the up-to-date benchmarks. The results show that novel BACs/CO2 pairs possess remarkably high adsorption performance, which will contribute towards the advancement of various adsorption-based technologies.

Adsorption of ampicillin sodium on activated carbons with different surface chemistries

BACKGROUND: The adsorption of ampicillin from aqueous solution by three types of activated carbon was investigated. The first was a commercial activated carbon (AC), the second (AAC) was AC modified by HNO3 oxidation and the third (HAAC) was AAC modified through thermal treatment. The surface properties of the activated carbon samples were characterized and the effects of pH and contact time on the adsorption were determined. The adsorption isotherms, adsorption kinetics and adsorption mechanism are discussed. RESULTS: Compared to AC, HNO3 oxidation increased the number of acid functional groups on the surface of AAC, which hindered the adsorption of ampicillin. For HAAC, thermal treatment removed surface oxygen groups and then improved the adsorption ability. The adsorption processes was greatly affected by pH and acidic conditions were favorable for adsorption. With an initial ampicillin sodium concentration of 200 mg/L, 9 h was needed for adsorption to reach equilibrium. The Langmuir isotherm provides a better fit for the adsorption than the Freundlich isotherm and the maximum adsorption capacities for AC, AAC and HAAC were 90.6, 59.8, 140.9 mg/g, respectively. The sorption kinetics can be described by a pseudo-second order model. CONCLUSION: The functional groups on activated carbon greatly affect its adsorption ability. The adsorption of ampicillin can be improved by increasing the number of basic functional groups on the activated carbon. Chemisorption was the dominant adsorption process and pH was an important factor affecting ampicillin adsorption.

The use of activated carbon from coffee endocarp for the manufacture of supercapacitors

Activated carbon (AC) was obtained from the dry endocarp of coffee for the manufacture of electrodes for supercapacitors. Four different AC samples were prepared via chemical methods at different proportions of impregnation (Xp) and two temperatures of activation (600 and 700 °C). Scanning Electron Microscopy technology and the measurement of the adsorption of N2 via the Brunauer–Emmett–Teller (BET) method were used to identify the morphological characteristics of AC, revealing high surface areas. Energy dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy techniques were applied for chemical composition analysis, identifying oxygenated functional groups which contribute to the increase in capacitance. The supercapacitor comprised two electrodes mounted on a tantalum cell, which was electrochemically evaluated by means of cyclic voltammetry and galvanostatic chronopotentiometry charge/discharge measurements. The maximum specific capacitance encountered was 186 Fg−1, which was obtained from the AC sample with a surface area of 734 m2g−1 and prepared at an Xp of 150% and an activation temperature of 700 °C. All AC samples exhibited good electrochemical performance.

Enhancing the performance of activated carbon based scalable supercapacitors by heat treatment

A biomass based activated carbon was prepared by chemical activation using ZnCl2 as an activation agent. Some of the activated carbon sample was subjected to a further single step heat treatment at 800 °C under an inert atmosphere. Both carbon samples (untreated and heat treated) were tested as supercapacitor electrode materials. Further heat treatment significantly affected the surface properties of the carbon sample. Furthermore, a substantial enhancement in electrochemical performance was achieved in both aqueous and organic electrolytes despite its reduced specific surface area. The supercapacitor device based on the organic electrolyte exhibited higher rate capability than the aqueous one (KOH). The supercapacitor device assembled from the heat treated sample based on the organic electrolyte was scaled up from coin size to pouch size and the electrochemical response was maintained. Both coin and pouch supercapacitors showed good capacitance retention for over 10,000 cycles. This is comparable to the commercial high-rate activated carbon based supercapacitors.

Exploring on the optimal preparation conditions of activated carbon produced from solid waste produced from sugar industry and Chinese medicine factory

The waste biomass produced from sugar industry and Chinese medicine factory such as bagasse, reed root residue, pueraria residue and liquorice residue were selected as the raw material for the preparation of activated carbon with zinc chloride as activator. With the same activation time, the influence of temperature and impregnation ratio on the preparation of activated carbon was investigated and the reasonable preparation conditions of activated carbon were monitored and analyzed. The obtained activated carbon samples were characterized by scanning electron microscopy, Brunauer–Emmett–Teller, methylene blue adsorption, thermogravimetric analysis and nitrogen adsorption–desorption. Analysis from the experimental data, bagasse, reed root residue, pueraria residue are suitable for preparing activated carbon. For bagasse, the optimum preparation condition was 700 °C and the impregnation ratio was 1:1, the adsorption capacity of methylene blue reached 246.83 mg/g at the moment. For reed root residue, the optimum preparation condition was 600 °C and the impregnation ratio was 1:2, the adsorption capacity of methylene blue reached 268.07 mg/g at the moment. For Pueraria residue, the optimum preparation condition was 700 °C and the impregnation ratio was 1:2. The adsorption capacity of methylene blue reached 297.33 mg/g at the moment.

Preparation of activated carbon from peanut shell with KOH activation and its application for H2S adsorption in confined space

Hydrogen sulfide (H2S), as a major air pollutant, poses a serious threat to people`s health, especially in confined spaces. In this study, a porous carbon filter was developed by impregnating a copper on activated carbon derived from peanut shell biomass. The carbonization temperature can significantly affect the texture properties of activated carbon, and the optimized temperature was 450 ℃. The optimal activated carbon sample (SBET = 1523.2 m2/g, Vmicro = 0.533 cm3/g) was prepared at a carbonization temperature of 450℃ and KOH activation at 750 ℃. The best adsorption performance was obtained with a copper impregnated optimal activated carbon (Cu/PAC-450) filter, and the maximum adsorption capacity was found to be 97.63 mg/g. As the initial concentration of H2S increased, the adsorption efficiency decreased. Adsorption isotherm and kinetic studies showed that Langmuir isotherm model was the best-fitted model for the adsorption of H2S on Cu/PAC-450 filter, with a correlation coefficient of 0.9627. The adsorption kinetic process followed the pseudo first order model, and the adsorption mechanism was controlled by intraparticle diffusion along with film diffusion model. The used Cu/PAC-450 filter can be successfully regenerated, which showed good reusability. The Cu/PAC-450 has a very broad prospect for use in household appliances (such as refrigerator, air conditioner, microwave oven, etc.) for indoor air purification. Therefore, this study is expected to expand the utilization of agriculture waste for the indoor air purification.

Preparation of Salacca Peel Based Activated Carbon using CeCl3 Catalyzed Hydrothermal Carbonization and Microwave Induced KOH Chemical Activation as Ni-Ion Capacitor Electrode

Activated carbon is a highly porous non-graphite carbon material. Activated carbon has been used for various applications, namely adsorbent, catalyst support and electrode. As supercapacitor’s electrode, activated carbon has a high energy density and fast charge - discharge. In this study, salacca peel used as precursor to synthesized activated carbon through hydrothermal carbonization (HTC) and microwave induced chemical activation. The hydrochar (HC) was synthesized at 225°C, 5 bar for 5 h using cerium (III) chloride as catalyst. Furthermore, KOH was used as activating agent at various HC to KOH mass ratio at 1:2 (CE2), 1:3 (CE3), and 1:4 (CE4), under microwave irradiation at 700 W for 8 min. Activated carbon samples were analyzed using methylene blue adsorption capacity method, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The CE4 sample gave highest methylene blue adsorption capacity, indicating high surface area. This sample was used as nickel ion’s capacitor electrode with nickel oxide as the reference electrode and 6 M KOH as the electrolyte. The electrochemical characteristic was studied using cyclic voltammetry (CV) with various scan rates (2 mV/s, 5 mV/s, 10 mV/s) for the nickel ion’s capacitor electrode. It was obtained that CE4 provided higher capacitance compared to commercial activated carbon.

Cycling system for decomposition of gaseous benzene by hydrogen peroxide with naturally Fe-containing activated carbon.

For the removal of volatile organic compounds (VOCs) from environmental systems, gaseous benzene, a model VOC, was adsorbed on naturally Fe-containing activated carbon and subsequently, decomposed in the presence of de-ionized water, and low (0.03%, pH 6.5) and high (30%, pH 2.5) concentration H2O2 solutions. The intermediates produced during benzene decomposition were analyzed and compared using gas chromatography-mass spectrometry. After the decomposition process, the activated carbon sample was air dried. Three cycles were carried out with de-ionized water and low and high concentration H2O2 solutions as oxidants. The adsorption capacity of the activated carbon sample treated with DI water gradually decreased as the number of cycles increased. On the other hand, the benzene adsorption capacity of the activated carbon samples treated with the H2O2 solutions was improved due to the relatively higher specific surface areas of these samples. After treatment with the low-concentration H2O2 solution, intermediates such as glyoxylic acid, oxalic acid, phenol, malonic acid, and pyrocatechol were observed. After treatment with high-concentration H2O2 solution, intermediates such as glyoxylic acid, formic acid, and acetic acid were formed. With increasing H2O2 concentration, the number and the molecular weight of the intermediate formed by the oxidative degradation of benzene, simultaneously decreased. The Fenton reaction induced by naturally Fe-containing activated carbon and H2O2 could lead to more efficient decomposition of benzene.

Activated Carbon Pruduction and Characterization Studies from Cane (<i>Phragmites australis</i>) by Microvave Assisted Pyrolsis Process

Activated carbon is an adsorption material with a large internal surface area and pore volume, which is obtained by the activation of the increasingly high content of carbon containing materials. Active carbon is used in the removal of organic pollutants and taste and odor disorders from household and industrial wastewater, as well as many areas such as various gas phase applications as well as the purification of chemical products. The cane grows spontaneously in lakes all of them in western Anatolia. Due to its easy accessibility and abundance, the cane is very economical to use it in production of activated carbon. The aim of this work is to obtain activated carbon from the cane, which as a cheap and an abundant raw material, by means of the quick microwave oven. Activated carbon production was carried out in two stages. In the first step sawdust of cane was activated with o-phosphoric acid solutions (30%, 40% and 50%). The second stage is carbonization in a microwave oven. Carbonization processes of 20 and 30 minutes were carried out at 300 and 450 watt microwave power levels. Methylene blue aqueous solutions were used for performance tests of the obtained activated carbon samples. BET surface area measurement, SEM photographs and FT-IR analyzes were used to determine the physical properties. It was concluded that 20 minutes of carbonization at the 300 watt microwave power level was sufficient for the studies. BET surface area of the best powder active carbon sample which is obtained in optimum conditions has been specified as 1096,9 m²/g.

ТЕРМОХИМИЧЕСКАЯ УТИЛИЗАЦИЯ ОТХОДОВ ТЕКСТОЛИТА С ПОЛУЧЕНИЕМ АКТИВНЫХ УГЛЕЙ С ОДНОРОДНОЙ МИКРОПОРИСТОЙ СТРУКТУРОЙ

The parameters of the process of thermochemical utilization of textolite waste are determined to obtain homogeneous porous carbon sorbents for ecological purposes, including pyrolysis of crushed textolite waste with subsequent activation of the resulting carbonizate with potassium hydroxide. The influence of the conditions of activation of carbonizates (mass ratio of carbonizate: KOH, temperature, duration of activation) on the formation of a porous structure and sorption activity of the obtained samples of active carbons (ACs) was studied. It was found that the adsorption capacity of the obtained AC samples for phenol is 1.75 times higher compared to the AC grade AG-3 widely used in the practice of wastewater treatment.

Fabrication and Characterization of Adding Coconut Shell Actived Nanocarbon to Lightweight Concrete

Coconut Shell actived Nanocarbon to Lightweight Concrete have done. LWC mixture of CS actived nanocarbon fillers made by mixing PPC cement, sand, broken stone, coconut shell actived nanocarbon fillers and water in various proportions. The ratio of CS actived nanocarbon on filler used (x = 0%, 5%, 10%, and 15%), with the aim of getting a different level of compressive strength testing. The particle size of activated CS carbon using the high temperature physical activation method 800C and chemistry (immersion of ZnCl2 solution) has an average diameter of 4,842.8 nm. The SEM shows that high porosity occurs and the shape is not homogeneous. EDS analysis to determine composition of the elements in the sample is known that the CS activated carbon samples have a maximum value in the element Carbon, Oxygen. The sample of CS actived Nanocarbon to LWC x = 0%, the results of the maximum value of % mass and % atom are the elements Oxygen, Carbon, and Calcium. For x = 10% the maximum value are the elements Oxygen, Carbon, and Silicon. The value of the strength of the objects in the CS activated carbon filler concrete sample (x = 5%) has maximum strength value 12.9 Mpa.

Analysis using image segmentation for the elemental composition of activated carbon

This article encompasses the method related to image segmentation of the Field Emission Scanning Electron Microscope (FESEM) images of Acacia Mangium Wood derived Activated Carbons under different conditions. Image segmentation using Hue-Saturation-Value (HSV) thresholding method was adapted to identify the different pattern composition in the grayscale images by varying the intensity Value (V) and keeping Hue (H) and Saturation (S) to zero, and each pattern was considered as one type of element that constituted the Activated Carbon. The algorithm was developed to compute the percentage of each pattern using non-zero pixels, and on the basis of different patterns, different elements having certain percentage of composition were recorded. Later, these results were compared with the Energy Dispersive X-ray Spectroscopy (EDS) to cross check the difference in percentage of each element present at the surface of the Activated Carbon. Part of this result is published in the article [1], “Comparison of surface properties of wood biomass Activated Carbons and their application against rhodamine B and methylene blue dye” Surfaces and Interfaces vol. 11 (2018) pp1–13.•The methods involved will be useful for characterization of Activated Carbon materials.•Image segmentation using HSV thresholding will inspire other researchers to apply similar concept on other materials.•Different patterns obtained for FESEM images using HSV thresholding was able to determine the presence of multiple elements present in the prepared Activated Carbon samples.