Upgrading recovered carbon black (rCB) from industrial-scale end-of-life tires (ELTs) pyrolysis to activated carbons: Material characterization and CO2 capture abilities

The current study presents for the first time how recovered carbon black (rCB) obtained directly from the industrial-scale end-of-life tires (ELTs) pyrolysis sector is applied as a precursor for activated carbons (ACs) with application in CO2 capture. The rCB shows better physical characteristics, including density and carbon structure, as well as chemical properties, such as a consistent composition and low impurity concentration, in comparison to the pyrolytic char. Potassium hydroxide and air in combination with heat treatment (500-900 °C) were applied as agents for the conventional chemical and physical activation of the material. The ACs were tested for their potential to capture CO2. Ultimate and proximate analysis, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), Raman spectroscopy, thermogravimetric analysis (TGA), and N2/CO2 gas adsorption/desorption isotherms were used as material characterization methods. Analysis revealed that KOH-activated carbon at 900 °C (AC-900K) exhibited the highest surface area and a pore volume that increased 6 and 3 times compared to pristine rCB. Moreover, the AC-900K possessed a well-developed dual porosity, corresponding to the 22% and 78% of micropore and mesopore volume, respectively. At 0 °C and 25 °C, AC-900K also showed a CO2 adsorption capacity equal to 30.90 cm3/g and 20.53 cm3/g at 1 bar, along with stable cyclic regeneration after 10 cycles. The high dependence of CO2 uptake on the micropore volume at width below 0.7-0.8 nm was identified. The selectivity towards CO2 in relation to N2 reached high values of 350.91 (CO2/N2 binary mixture) and 59.70 (15% CO2/85% N2).

Functional Activated Biocarbons Based on Biomass Waste for CO2 Capture and Heavy Metal Sorption

Inexpensive porous activated biocarbons were prepared from biomass and agriculture waste following the method of thermal and hydrothermal carbonization and activation with superheated water vapor. The activated biocarbons were characterized by nitrogen adsorption-desorption at 77 K, SEM, XRD, Raman spectrometry, FTIR spectroscopy, determination of particle size, and elemental composition by XRF. The specific surface area was in the range of 240-709 m2/g, and the total pore volume was from 0.12 to 0.43 cm3/g. The percentage of microporosity in activated biocarbons was 89-92%. These activated biocarbons have been used for CO2 and heavy metal sorption. Activated biocarbons based on pine cones and birch prepared by thermal carbonization and activation with superheated water vapor had the highest ability to capture CO2 and amounted to 6.43 and 6.00 mmol/g at 273 K, as well as 4.57 and 4.22 mmol/g at 298 K, respectively. The best activated biocarbon was characterized by unchanged stability after 30 adsorption and desorption cycles. It was proved that the adsorption of CO2 depends on narrow micropores (<1 nm). Activated biocarbons have also been analyzed as effective adsorbents for removing Cu2+, Zn2+, Fe2+, Ni2+, Co2+, and Pb2+ ions from aqueous solutions. Activated biocarbons are effective adsorbents for the removal of lead and zinc ions from aqueous solutions.

Sulfur-Doped g-C3N4 Heterojunctions for Efficient Visible Light Degradation of Methylene Blue

The discharge of synthetic dyes from different industrial sources has become a global issue of concern. Enormous amounts are released into wastewater each year, causing concerns due to the high toxic consequences. Photocatalytic semiconductors appear as a green and sustainable form of remediation. Among them, graphitic carbon nitride (g-C3N4) has been widely studied due to its low cost and ease of fabrication. In this work, the synthesis, characterization, and photocatalytic study over methylene blue of undoped, B/S-doped, and exfoliated heterojunctions of g-C3N4 are presented. The evaluation of the photocatalytic performance showed that exfoliated undoped/S-doped heterojunctions with 25, 50, and 75 mass % of S-doped (g-C3N4) present enhanced activity with an apparent reaction rate constant (kapp) of 1.92 × 10-2 min-1 for the 75% sample. These results are supported by photoluminescence (PL) experiments showing that this heterojunction presents the less probable electron-hole recombination. UV-vis diffuse reflectance and valence band-X-ray photoelectron spectroscopy (VB-XPS) allowed the calculation of the band-gap and the valence band positions, suggesting a band structure diagram describing a type I heterojunction. The photocatalytic activities calculated demonstrate that this property is related to the surface area and porosity of the samples, the semiconductor nature of the g-C3N4 structure, and, in this case, the heterojunction that modifies the band structure. These results are of great importance considering that scarce reports are found concerning exfoliated B/S-doped heterojunctions.

Mechanochemical Degradation of Caffeine and Diclofenac Using Biochar of Fique Bagasse in the Presence of Al: Monitoring by Mass Spectrometry

Much research has been carried out to remove emerging contaminants using diverse materials. Furthermore, studies related to pollutant degradation have increased over the past decade. Mechanochemical degradation can successfully decompose molecules that are persistent in the environment. In this study, the biochar of fique bagasse with mixtures SiO2, Al, Al2O3, and Al-Al2O3 was treated with a mechanochemical technique using a planetary ball mill to investigate the degradation of caffeine and diclofenac. These tests resulted in the transformation of caffeine and diclofenac due to the use of Al employing mechanochemistry. In fact, through the use of liquid chromatography coupled with mass spectrometry, eight and six subproducts were identified for caffeine and diclofenac, respectively. Additionally, analysis of the molecules proposed for caffeine and diclofenac transformation suggested hydroxylation, demethylation, decarboxylation, oxidation reactions, and cleavage of the C-C and C-N bonds in the pollutants studied. The formation of these transformation products could be possible by reductant oxygen species generated from the molecular oxygen in the presence of aluminum and the energy delivered for ball milling. The results obtained show the potential application in the environmental management of mechanochemical treatment in the elimination of emerging contaminants caffeine and diclofenac.

CO2 adsorption on carbonaceous materials obtained from forestry and urban waste materials: a comparative study

The increasing emissions of gaseous pollutants of anthropogenic origin, such as carbon dioxide (CO2), which causes global warming, have raised great interest in developing and improving processes that allow their mitigation. Among them, adsorption on porous materials has been proposed as a sustainable alternative. This work presents a study of CO2 equilibrium adsorption at low temperatures (0, 10, and 20 °C) over a wide range of low pressures, on activated carbon derived from Eucalyptus (ES) and Patula pine (PP) forest waste, and carbonaceous material derived from waste tires (WT). The precursors of these materials were previously prepared, and their physicochemical properties were characterized. ES and PP were thermochemically treated with phosphoric acid, and WT was oxidized with nitric acid. Additionally, these materials were used to obtain monoliths using uniaxial compaction techniques and different binding agents, with better results obtained with montmorillonite. A total of six adsorbent solids had their textural and chemical properties characterized and were tested for CO2 adsorption. The highest specific surface area (1405 m2 g-1), and micropore properties were found for activated carbon derived from Eucalyptus whose highest adsorption capacity ranged from 2.27 mmol g-1 (at 0 °C and 100 kPa) to 1.60 mmol g-1 (at 20 °C and 100 kPa). The activated carbon monoliths presented the lowest CO2 adsorption capacities; however, the studied materials showed high potential for CO2 capture and storage applications at high pressures. The isosteric heats of adsorption were also estimated for all the materials and ranged from 16 to 45 kJ mol-1 at very low coverage explained by the energetic heterogeneity and weak repulsive interactions among adsorbed CO2 molecules.

Biodiesel Production Using Palm Oil with a MOF-Lipase B Biocatalyst from Candida Antarctica: A Kinetic and Thermodynamic Study

This research presents the results of the immobilization of Candida Antarctica Lipase B (CALB) on MOF-199 and ZIF-8 and its use in the production of biodiesel through the transesterification reaction using African Palm Oil (APO). The results show that the highest adsorption capacity, the 26.9 mg·g^-1 Lipase, was achieved using ZIF-8 at 45 °C and an initial protein concentration of 1.20 mg·mL^-1. The results obtained for the adsorption equilibrium studies allow us to infer that CALB was physically adsorbed on ZIF-8 while chemically adsorbed with MOF-199. It was determined that the adsorption between Lipase and the MOFs under study better fit the Sips isotherm model. The results of the kinetic studies show that adsorption kinetics follow the Elovich model for the two synthesized biocatalysts. This research shows that under the experimental conditions in which the studies were carried out, the adsorption processes are a function of the intraparticle and film diffusion models. According to the results, the prepared biocatalysts showed a high efficiency in the transesterification reaction to produce biodiesel, with methanol as a co-solvent medium. In this work, the catalytic studies for the imidazolate, ZIF-8, presented more catalytic activity when used with CALB. This system presented 95% biodiesel conversion, while the biocatalyst formed by MOF-199 and CALB generated a catalytic conversion percentage of 90%. Although both percentages are high, it should be noted that CALB-MOF-199 presented better reusability, which is due to chemical interactions.

Competitive Adsorption of Caffeine and Diclofenac Sodium onto Biochars Derived from Fique Bagasse: An Immersion Calorimetry Study

Pharmaceuticals, including caffeine (CFN) and diclofenac sodium (DCF), are a group of emerging pollutants which have the capacity to prompt harmful effects in flora and fauna, even at relatively low concentrations. Additionally, CFN has been determined as one of the most ubiquitous active compounds in the natural environment, whereas DCF is a widely used nonsteroidal anti-inflammatory drug that has been detected in environmental sources around the world. Conversely, the fique is a plant of the Agavaceae family and of the Fucraea genus.Two native species are cultivated in Colombia, Furcraea cabuya and Furcrae macrophylla, in order to extract their fiber, but in this process a lot of waste is produced. In this study, with the fique residues, thermochemical treatments were carried out and 5 biochar samples were obtained, which were calorimetrically characterized and used to investigate their behavior in competitive adsorption of DCF and CFN. The results of the calorimetric studies show that the biochar prepared from fique bagasse have different porous and chemical characteristics, which is related to the different treatments that were used at the time of their preparation. In addition, it was established that the results of the adsorbate-adsorbent interactions determined by calorimetry allow correlation of the adsorption processes of the molecules under study (CFN and DCF). The results show that the NaOH fique biochar (FB850-3Na) presents the highest adsorption capacity in both simple and competitive tests.

Biodiesel Production from Transesterification with Lipase from Pseudomonas cepacia Immobilized on Modified Structured Metal Organic Materials

This research presents the modification of MOF-199 and ZIF-8 using furfuryl alcohol (FA) as a carbon source to subsequently fix lipase from Pseudomonas cepacia and use these biocatalysts in the transesterification of African palm oil (APO). The need to overcome the disadvantages of free lipases in the biodiesel production process led to the use of metal organic framework (MOF)-type supports because they provide greater thermal stability and separation of the catalytic phase, thus improving the activity and efficiency in relation to the use of free lipase, disadvantages that could not be overcome with the use of other types of catalysts used in transesterification/esterification reactions for the production of biodiesel. The modification of MOFs ZIF-8 and MOF-199 with FA increases the pore volume which allows better immobilization of Pseudomonas cepacia lipase (PCL). The results show that these biocatalysts undergo transesterification with biodiesel yields above 90%. Additionally, studies were carried out on the effect of (1) enzyme loading, 2) enzyme immobilization time, (3) enzyme immobilization temperature, and (4) pH on the % immobilization of the enzyme and the specific activity. The results show that the highest immobilization efficiency for the FA@ZIF-8 support has a value of 91.2% when the load of this support was 3.5 mg/mg and has a specific activity of 142.5 U/g protein. The FA@MOF-199 support presented 80.3% enzyme immobilization and 125% U/g specific activity protein. We established that the specific activity increases in the period from 0.5 to 5.0 h for the systems under investigation. After this time, both the specific activity and the % efficiency of enzyme immobilization decrease. Therefore, 5.0 h (immobilization efficiency of 95 and 85% for FA@MOF-199, respectively) was chosen as the most appropriate time for PCL immobilization. Methods of adding methanol, with three and four steps, were tested, where biodiesel yields greater than 90% were obtained for the biocatalysts synthesized in this work (FA@ZIF-8-PCL and FA@MOF-199-PCL) and above 70% for free PCL, and the maximum yield was reached at a molar ratio between methanol and APO of 4:1 when using the one-step method under the same reaction conditions (as mentioned above). Only the results of FA@ZIF-8-PCL are presented here; however, it should be noted that the results for biocatalyst FA@MOF-199-PCL and lipase-free PCL presented the same behavior. The order of biocatalyst performance was FA@ZIF-8-PCL > FA@MOF-199-PCL > PCL-Free, which demonstrates that the use of FA as a modifier is a novel aspect in the conversion of palm oil into biodiesel components.

Biogenic Hydroxyapatite Obtained from Bone Wastes Using CO2-Assisted Pyrolysis and Its Interaction with Glyphosate: A Computational and Experimental Study

In this work, biogenic hydroxyapatite (BHap) obtained from cattle bone waste is proposed as an adsorbent of this dangerous pollutant. Density functional theory (DFT) and calorimetric studies were developed to study the interaction between BHap and glyphosate (GLY). A strong interaction was found in the experiments through the measurement of immersion enthalpy, confirmed by the exothermic chemisorption obtained with DFT calculations. These results suggest that hydroxyapatite is a promising adsorbent material for GLY adsorption in aqueous solutions. In addition, it was determined that the GLY-hydroxyapatite interaction is greater than the water-hydroxyapatite interaction, which favors the GLY adsorption into this material.

Data for the synthesis, characterization, and use of xerogels as adsorbents for the removal of fluoride and bromide in aqueous phase

Groundwater with high fluoride concentrations has been recognized as one of the serious concerns worldwide. Besides, the fluoride released into the groundwater by slow dissolution of fluoride-containing rocks, various industries also contribute to fluoride pollution [1]. Excess intake of fluoride leads to various health problems such as dental and skeletal fluorosis, cancer, infertility, brain damage, thyroid diseases, etc. [2]. On the other hand, bromide is naturally present in surface and groundwater sources. However, during the chlorination process, bromide can be oxidized to HOBr, which can react with natural organic matter in water to form brominated organic disinfection byproducts, which are very harmful to human health [3]. Among various methods for water treatment, the adsorption process has been widely used and seems to be an efficient and attractive method for the removal of many contaminants in water, such as anions, in terms of cost, simplicity of design, and operation [4], [5]. In the past years, xerogels and carbon xerogels, a new type of adsorbents, which are synthesized by the sol-gel polycondensation of resorcinol and formaldehyde, have gained attention due to their moldable texture and chemical properties [6]. Moreover, melamine addition in resorcinol and formaldehyde xerogels adds basic groups on its surface, favouring Lewis acid-base interactions between xerogels and other components by adsorption [7].

In this data article, the synthesis of three resorcinol-formaldehyde (R/F) xerogels with an increasing amount of melamine (M) was carried out by colloidal polymerization (molar ratios of M/R = 0.5, M/R = 1.0, and M/R = 2.0). Additionally, samples of M/R = 0.5 xerogel were carbonized at 400, 450, and 550 °C under an inert atmosphere to increase their specific area. Organic and carbon xerogels obtained were characterized by FTIR, TGA, SEM, Physisorption of N₂, and the pH at the point of zero charge (pH_PZC). All organic xerogels were also tested as adsorbents on the removal of fluoride and bromide ions from aqueous phase. The Freundlich, Langmuir, and Radke-Prausnitz isotherm models were applied to interpret the experimental data from adsorption equilibrium. Additionally, the data of the mass of the xerogel needed to remove fluoride and bromide from groundwater and fulfill the maximum concentration levels are also included.

Kinetic Study of Waste Tire Pyrolysis Using Thermogravimetric Analysis

The influence of particle size (0.3 and 5.0 mm) and heating rate (5, 10, and 20 °C min^-1) on the kinetic parameters of pyrolysis of waste tire was studied by thermogravimetric analysis and mathematical modeling. Kinetic parameters were determined using the Friedman model, the Coats-Redfern model, and the ASTM E1641 standard based on Arrhenius linearization. In the Friedman model, the activation energy was between 40 and 117 kJ mol^-1 for a particle size of 0.3 mm and between 23 and 119 kJ mol^-1 for a particle size of 5.0 mm. In the Coats-Redfern model, the activation energy is in a range of 46 to 87 kJ mol^-1 for a particle size of 0.3 mm and in a range of 43 to 124 kJ mol^-1 for a particle size of 5.0 mm. Finally, in the ASTM E1641 standard, the activation energy calculated was between 56 and 60 kJ mol^-1 for both particle sizes. This study was performed to obtain kinetic parameters from different mathematical methods, examining how the particle size and heating rate influence them.

Understanding the solid-liquid equilibria between paracetamol and activated carbon: Thermodynamic approach of the interactions adsorbent-adsorbate using equilibrium, kinetic and calorimetry data

In this work, we presented the paracetamol-activated carbon interactions and their effect on the adsorption capacity. We evaluated kinetic, equilibrium, and calorimetric data using different solvents (water, HCl 0.1 M, and NaCl 0.1 M) to evaluate the changes in the adsorbent-adsorbate interaction. In addition, the commercial activated carbon (AC) was modified through thermal (ACTT) and chemical (ACNA) methods to change the physicochemical properties of the adsorbents. The relative kinetic constants decrease with the content of basic groups on the activated carbon, indicating a lower influence of diffusion on the adsorption rate when the chemical interactions increase (0.1 _ACNA >0.09 _AC >0.03 _ACTT mmol g^-1). The adsorption capacity for AC at acidic pH increases slightly compared to tests carried out in the water. Under this condition, the adsorbed amount of paracetamol was 1.31 mmol g^-1. However, the maximum adsorption capacity was achieved on ACTT using water as solvent (1.57 mmol g^-1). The paracetamol adsorbed decreases in NaCl (osmotic, ionic strength) on all activated carbons by around 20%. The interaction enthalpy of the paracetamol-activated carbon interaction presents values between - 18.0 and 2.3 J per molecule adsorbed. The Gibbs energy released during the adsorption process is between - 33.1 and - 29.8 kJ mol^-1.

Enthalpies of Immersion in Caffeine and Glyphosate Aqueous Solutions of SBA-15 and Amino-Functionalized SBA-15

Mesostructured silica SBA-15 and amino-functionalized silica SBA-15-NH₂ were synthesized, and then, characterization, adsorption capacity, and immersion enthalpies in caffeine and glyphosate on SBA-15 and SBA-15-NH₂ were evaluated. The enthalpy parameter was determined using a local construction Tian-type heat conduction calorimeter. Calorimetric studies in caffeine solutions exhibit negative enthalpy values; exothermic process characteristics for SBA-15 were between -13.90 and -194.06 J g^-1 and those for SBA-15-NH₂ were between -7.22 and -60.34 J g^-1, and the adsorption capacity of caffeine was better in SBA-15 than that in SBA-15-NH₂. In contrast, the enthalpies of immersion in glyphosate solutions were -5.06 to -56.2 J g^-1 and the immersion of SBA-15-NH₂ in each solution generated enthalpy values of -9.06 to -41.2 J g^-1, but the adsorption capacity of glyphosate was better in the amino-functionalized SBA-15. The results show that functionalization of SBA-15 produced differences in physicochemical characteristics of solids, since energy and affinity for the calorimetric liquids are related to the surface properties of solids as well as the chemical nature of the target molecule, immersion enthalpy, was different.

Study of Mercury [Hg(II)] Adsorption from Aqueous Solution on Functionalized Activated Carbon

Mercury and its compounds are toxic substances, whose uncontrolled presence in the environment represents a danger to ecosystems and the organisms that inhabit in it. For this reason, in this work, we carried out a study of mercury [Hg(II)] adsorption from aqueous solution on functionalized activated carbon. The activated carbons were prepared by chemical activation of a mango seed with solutions of CaCl₂ and H₂SO₄ at different concentrations, later, the carbonaceous materials were functionalized with Na₂S, with the aim of increasing the sulfur content in the carbonaceous matrix and its affinity to mercury. The materials were characterized using: proximal analysis, scanning electron microscopy, Boehm titrations, point zero charge (pH_PZC), and infrared spectroscopy. Additionally, immersion calorimetries were performed in the mercury solution. The results of textural and chemical characterization show materials with low Brunauer-Emmett-Teller (BET) surface areas between 2 and 33 m²·g^-1 and low pore volumes. However, they had a rich surface chemistry of oxygenated groups. The enthalpies of immersion in the mercury solutions are between -31.71 and -77.31 J·g^-1, showing a correlation between the magnitude of the enthalpic data and the adsorption capacity of the materials. It was evidenced that the functionalization process produces a decrease in the surface area and pore volume of the activated carbons, and an increase in the sulfur content of the carbonaceous matrix. It was evidenced that the functionalization process generated an increase in the mercury [Hg(II)] adsorption capacity between 21 and 49% compared to those of the nonfunctionalized materials, reaching a maximum adsorption capacity of 85.6 mgHg²⁺g^-1.

Enthalpic and Liquid-Phase Adsorption Study of Toluene-Cyclohexane and Toluene-Hexane Binary Systems on Modified Activated Carbons

The liquid-phase adsorption of toluene in cyclohexane and hexane solutions on modified activated carbons was evaluated; the energy involved in the interaction between these solutions and the solids was determined by immersion enthalpies of pure solvents and their mixtures, and the contribution of the system constituents was calculated by differential enthalpies. The thermal treatment generated modifications that favored adsorption and interaction with the evaluated solutions, since it increased the textural parameters and the basic character of the samples. Cyclohexane could create greater competition with the adsorption sites compared to hexane, but it favored the increase in adsorption capacities (0.416 to 1.026 mmol g⁻¹) and the interactions with the solid evaluated through the immersion enthalpies. The immersion enthalpies of pure solvents (−16.36 to −112.7 J g⁻¹) and mixtures (−25.65 to −104.34 J g⁻¹) had exothermic behaviors that were decreasing due to the possible displacement of solvent molecules when increasing the solute concentration in the mixtures. The differential enthalpies for toluene were negative (−18.63 to −2.14 J), mainly due to the π–π interaction with the solid, while those of the solvent–solid component tended to be positive values (−4.25 to 55.97 J) due to the displacement of the solvent molecules by those of toluene.

Study of CO2 Adsorption on Chemically Modified Activated Carbon With Nitric Acid and Ammonium Aqueous

The study of CO₂ adsorption on adsorbent materials is a current topic of research interest. Although in real operating circumstances, the removal conditions of this gas is carried out at temperatures between 290 and 303 K and 1 Bar of pressure or high pressures, it is useful, as a preliminary approach, to determine CO₂ adsorption capacity at 273K and 1 Bar and perform a thermodynamic study of the CO₂ adsorption heats on carbonaceous materials prepared by chemical activation from African palm shell with CaCl₂ and H₃PO₄ solutions, later modified with HNO₃ and NH₄OH, with the aim to establish the influence that these treatments have on the textural and chemical properties of the activated carbons and their relationship with the CO₂ adsorption capacity. The carbonaceous materials were characterized by physical adsorption of N₂ at 77K, CO₂ at 273K, proximate analysis, Boehm titrations and immersion calorimetry in water and benzene. Activated carbons had a BET area between 634 and 865 m²g⁻¹, with a micropore volume between 0.25 and 0.34 cm³g⁻¹. The experimental results indicated that the modification of activated carbon with HNO₃ and NH₄OH generated a decrease in the surface area and pore volume of the material, as well as an increase in surface groups that favored the adsorption of CO₂, which was evidenced by an increase in the adsorption capacity and the heat of adsorption.

Dataset on adsorption of phenol onto activated carbons: Equilibrium, kinetics and mechanism of adsorption

Two activated carbons (AC) prepared from onion leaves (OL) (Allium fistulosum) and palm kernel shell (PS) (Elaeis guineesis) were used to adsorb phenol from aqueous solution. Adsorption kinetics was studied by Pseudo-first order (PFO) and Pseudo-second order (PSO) models, while equilibrium was modelled using Langmuir, Freundlich, Toth and Redlich Peterson isotherms. Adsorption mechanism was analyzed applying Boyd and intraparticle diffusion models. The parameters of each one of the models were calculated using Minitab17® by non-linear regression. Piecewise linear regression was applied to calculate the parameters of Boyd and intraparticle diffusion models. Phenol adsorption onto activated carbons is describe better by Langmuir isotherm and PSO kinetic model. Maximum adsorption capacity was between 30 and 40 mg.g⁻¹.

A new methodology to determine the effect of the adsorbate-adsorbent interactions on the analgesic adsorption onto activated carbon using kinetic and calorimetry data

This work proposes a new methodology to determine the adsorption mechanism for salicylic acid and paracetamol on activated carbon based on the physicochemical characteristics of adsorbent and adsorbates. The methodology is divided into two parts: the determination of adsorption kinetics (order and mechanism) and the study of the chemical interactions (adsorbate-adsorbent and solvent-adsorbent) using calorimetry tests. Then, the results obtained in both techniques were correlated with the amount of drug adsorbed. The adsorption kinetics of salicylic acid and paracetamol on activated carbons with different oxygen contents could be described with widely kinetic models such as intraparticle, pseudo-first-order, pseudo-second-order, Avrami, and Elovich models; different information about the adsorption mechanism are offered by each of them. The results indicated that the pseudo-first-order rate constant decreases with the molecular size of analgesics and the carboxylic acid groups on the adsorbent surface; the rate constant values are between 0.12 and 2.31 h^-1. The adsorbed amount of analgesics and the adsorption rate are greatest on activated carbons with basic characteristics (Q_RAC 0.45 > 0.24 > 0.21 mmol g^-1 for phenol, salicylic acid, and paracetamol, respectively). The enthalpy changes follow the same trend in all activated carbons; for RAC, the results were ΔH_immPHEN = - 33.4 J g^-1, ΔH_immSA = - 35.9 J g^-1, and ΔH_immPAR = - 45.4 J g^-1. The analgesic diffusion rate in the boundary layer increases with the formation of adsorbate-adsorbent interactions (exothermic process).

Graphene Oxide: Study of Pore Size Distribution and Surface Chemistry Using Immersion Calorimetry

In this work, the textural parameters of graphene oxide (GO) and graphite (Gr) samples were determined. The non-local density functional theory (NLDFT) and quenched solid density functional theory (QSDFT) kernels were used to evaluate the pore size distribution (PSD) by modeling the pores as slit, cylinder and slit-cylinder. The PSD results were compared with the immersion enthalpies obtained using molecules with different kinetic diameter (between 0.272 nm and 1.50 nm). Determination of immersion enthalpy showed to track PSD for GO and graphite (Gr), which was used as a comparison solid. Additionally, the functional groups of Gr and GO were determined by the Boehm method. Donor number (DN) Gutmann was used as criteria to establish the relationship between the immersion enthalpy and the parameter of the probe molecules. It was found that according to the Gutmann DN the immersion enthalpy presented different values that were a function of the chemical groups of the materials. Finally, the experimental and modeling results were critically discussed.

Adsorption of Pharmaceutical Aromatic Pollutants on Heat-Treated Activated Carbons: Effect of Carbonaceous Structure and the Adsorbent-Adsorbate Interactions

Drugs are considered emerging pollutants from water sources and are therefore considered to be of high toxicological risk to aquatic fauna. Activated carbon adsorption is one of the methods approved by the Word Health Organization to remove pharmaceutical compounds from water in treatment plants due to its cost and easy implementation. This study presents the modification of a commercial activated carbon by heat treatment at 1073, 1173, and 1273 K. The impact of the physicochemical changes of the adsorbent on the adsorption capacity of salicylic acid and methylparaben, compounds derived from phenol, was studied. Finally, the adsorbate-adsorbent interactions are evaluated through immersion calorimetry. It is observed that at 1173 K, activated carbon increases its surface area by 29%. At higher temperatures, the surface area drops to 21%. In the activated carbon subjected to heat treatment at 1173 K, it increases the adsorption capacity of salicylic acid and methylparaben by 24 and 34%, respectively, compared to activated carbons subjected to higher temperatures. The interaction enthalpies (adsorbate-adsorbent interaction) have values between -12 and 5 J g^-1.

Preparation and Characterization of Graphene Oxide for Pb(II) and Zn(II) Ions Adsorption from Aqueous Solution: Experimental, Thermodynamic and Kinetic Study

A thermodynamic and kinetic study of the adsorption process of Zn (II) and Pb (II) ions from aqueous solution on the surface of graphene oxide (GO) to establish the mechanisms of adsorbate–adsorbent interaction on this surface. The effect of pH on the retention capacity was studied and adsorption isotherms were determined from aqueous solution of the ions; once the experimental data was obtained, the kinetic and thermodynamic study of the sorption process was carried out. The data were fitted to the Langmuir, Freundlich, Dubinin-Raduskevich and Temkin isotherm models. The results showed that Zn(II) and Pb(II) on the GO adsorbing surface fitted the Langmuir model with correlation coefficients (R²) of 0.996. Kinetic models studied showed that a pseudo-second-order model was followed and thermodynamically, the process was spontaneous according to the values of Gibbs free energy (ΔG^o). N₂ adsorption isotherms were determined and modeled with the NLDFT (nonlocal density functional theory) and QSDFT (quenched solid density functional theory) kernels.

Adsorption of CO2 on Activated Carbons Prepared by Chemical Activation with Cupric Nitrate

Activated carbons were prepared from a lignocellulosic material, African palm shells (Elaeis guineensis), by chemical impregnation of the precursor with solutions of 1-7% w/v Cu(NO₃)₂ at five different concentrations. These were carbonized in a carbon dioxide atmosphere at 1073 K to obtain different carbons. Their textural properties were characterized by nitrogen and carbon dioxide adsorption isotherms in order to evaluate the pore-size distribution. The immersion enthalpies of the activated carbons in benzene, dichloromethane, and water were determined. The CO₂ adsorption capacities of the materials at 273 K under low-pressure conditions were also determined. Chemical characterization was performed by mass spectrometry, Fourier transform infrared spectroscopy, and temperature-programmed reduction. With this method of preparation under the concentrations described, activated micro-mesoporous carbons were obtained, with the formation of highly mesoporous solids that favored the process of diffusion of molecules of CO₂ into the material. Here, we show that activated carbons were obtained with different textural characteristics: surface Brunauer-Emmett-Teller areas varied between 473 and 1361 m² g^-1 and micropore volume between 0.18 and 0.51 cm³ g^-1. The activated carbon with the highest values of textural parameters was ACCu5-1073. Micro-mesoporous solids were obtained with the methodology used. This is important as it may help the entry of CO₂ molecules into the pores. The adsorption of CO₂ in the materials prepared presented values between 103 and 217 mg CO₂ g^-1; the values of volume of narrow microporosity obtained were between 0.16 and 0.45 cm³ g^-1. The solid with the greatest capacity for adsorption of CO₂ and volume of narrow microporosity was ACCu3-1073. The use of these solids is of importance for future practical and industrial applications. The adsorption kinetic of CO₂ in the activated carbons prepared with metallic salt of copper is in good accordance with the intraparticle diffusion model, for which diffusion is the rate-limiting step. The adsorption of CO₂ in the prepared activated carbons is favorable from the energy and kinetic point of view, as these accompanied by the presence of wide micro-mesoporosity favor the entry of CO₂ into the micropores.

Biochar from Fique Bagasse for Remotion of Caffeine and Diclofenac from Aqueous Solution

Caffeine and diclofenac are molecules with high human intake, and both belong to the ‘emergent’ class of contaminants. These compounds have been found at different concentrations in many sources of water worldwide and have several negative impacts on aquatic life systems; that is why the search for new alternatives for their removal from aqueous media is of transcendental importance. In this sense, adsorption processes are an option to attack this problem and for this reason, biochar could be a good alternative. In this regard, were prepared six different biochar from fique bagasse (FB), a useless agroindustry by-product from fique processing. The six biochar preparations were characterized through several physicochemical procedures, while for the adsorption processes, pH, adsorption time and concentration of caffeine and diclofenac were evaluated. Results showed that the biochar obtained by pyrolysis at 850 °C and residence time of 3 h, labeled as FB850-3, was the material with the highest adsorbent capacity with values of 40.2 mg g⁻¹ and 5.40 mg g⁻¹ for caffeine and diclofenac, respectively. It was also shown that the experimental data from FB850-3 fitted very well the Redlich–Peterson isotherm model and followed a pseudo-first and pseudo-second-order kinetic for caffeine and diclofenac, respectively.

Thermodynamic data of phenol adsorption on chemically modified activated carbons

The presence of phenol in water bodies exists due to the discharge of wastewater from industrial, agricultural and domestic activities. Its presence in water is associated with a decrease in the quality of drinking water because its change the taste and odour [1]. The adsorption process is one of the most used treatments to remove the phenol of waters and the activated carbon is an appropriate adsorbent due to its high surface area, porosity and low cost.

The studies about the adsorption process are addressed by different views of point such as equilibrium and thermodynamic data. In this work, the adsorption isotherms of phenol on five activated carbons with different physicochemical properties in aqueous solution are presented. In addition, the immersion enthalpies, the interaction enthalpies, the Gibbs energy and the entropy changes are included.

The isotherms data are adjusted to the Freundlich and Sips models. The immersion enthalpy values are between −7.670 and −57.0 J g⁻¹, the interaction enthalpies are between 48.00 and −11.70 J g⁻¹, the Gibbs energy change are between −5337 and −12322 J mol⁻¹ K⁻¹ and finally, the entropy change values are between 18.10 and 39.70 J K⁻¹.

Use of bone char prepared from an invasive species, pleco fish (Pterygoplichthys spp.), to remove fluoride and Cadmium(II) in water

In this study, bone char (BC) from pleco fish (Pterygoplichthys spp.) was synthesized, and their textural and physicochemical properties, as well as its adsorption capacity towards fluoride and Cd(II) from single and binary aqueous solutions, were determined. The results showed that the properties of the BCs were independent of the type of bone used and the surface areas were close to 110 m² g^-1. The effect of solution pH revealed that the adsorption capacity of BC towards fluoride from water raised by decreasing the solution pH. This trend was attributed to the electrostatic interaction between the positively charged surface and the fluoride in aqueous solution. On the contrary, the capacity of BC for adsorbing Cd(II) was enhanced by increasing the solution pH, indicating that electrostatic interactions were also essential but with a contrary effect in comparison with fluoride adsorption due to the negatively charged surface at pH above the point zero charge (pH_PZC = 8.16). The experimental data for binary adsorption of fluoride and Cd(II) were interpreted satisfactorily using the modified Freundlich multicomponent isotherm (EFMI), and the experimental data revealed that Cd(II) have an antagonistic effect on the adsorption of fluoride, whereas the presence of fluoride does not affect the capacity of BC for adsorbing Cd(II). Thermogravimetric, XRD diffraction and IR spectroscopy analysis corroborated that the adsorption of fluoride in BC is due to electrostatic attractions, ion exchange or chemisorption and physisorption. Besides, the removal of Cd(II) occurs by physical adsorption and ion exchange. It was concluded that BC is an alternative material for the removal of fluoride and Cd(II) from aqueous solutions, and it is a possible application for using the bones of this invasive fish species.

Data of preparation and characterization of activated carbon using two activant agents and mango seed as precursor material

The aim of this research is to prepare various carbonaceous materials with different textural, structural and chemical characteristics, using mango seed a rarely used residue for the preparation of activated carbons, as the precursor material. The mango seed was analyzed by TGA and SEM also methodological data about the preparation of activated carbons are provided. Four activated carbons were prepared using sulfuric acid (H₂SO₄) and calcium chloride (CaCl₂) as activating agents and were characterized by means of TGA, SEM/EDX, Boehm Titration, isotherm determination of N₂ adsorption-desorption at −196 °C and immersion calorimetry. Four carbons were obtained with superficial areas BET between 6 and 33 m² g⁻¹ and different chemical characteristics associated with the changes in the concentration of the activating agents. The activated carbons that were prepared with the highest activating agent concentrations, obtained better results in the amount of oxygenated surface groups, the total acidity and the amount of fixed carbon. The enthalpy of immersion in water was between 7 and 16 J g⁻¹.

Interaction between Hydrocarbons C6 and Modified Activated Carbons: Correlation between Adsorption Isotherms and Immersion Enthalpies

Adsorption isotherms of benzene, cyclohexane, and hexane were determined from the gas phase on microporous activated carbons with Brunauer-Emmett-Teller areas between 816 and 996 m² g^-1. The Dubinin-Radushkevich equation was used to calculate the parameters of characteristic energy E _o and micropore volume W _o. Also, immersion enthalpies of activated carbons in solvents were obtained (benzene: -95.0 to -145.1 J g^-1; cyclohexane: -21.2 to -91.7 J g^-1; and hexane: -16.4 to -66.1 J g^-1), and they were used to calculate the product E _o W _o with the Stoeckli and Kraehenbuehl equations. Subsequently, values of E _o W _o from the two techniques (between 512 and 2223 J cm³ mol^-1 g^-1 for the adsorption isotherms; between 1204 and 12008 J cm³ mol^-1 g^-1 for immersion enthalpies) were correlated with some characteristics of the adsorbate such as molecular size, the molar volume, and the dielectric constant. It was found that modifying the activated carbon affected the adsorption process, being favored by temperature changes and restricted by oxidation processes. The adsorbate, which showed the highest values for E _o W _o, was benzene, because it had a smaller molecular size and a higher dielectric constant.

Initial Approximation to the Design and Construction of a Photocatalysis Reactor for Phenol Degradation with TiO2 Nanoparticles

A photoreactor was designed, built, and optimized to carry out the degradation of phenol. To achieve this, phenol concentration was used as the reference to compare the photocatalysis reaction efficiency obtained through this research with results from other studies. Additionally, during the building process, different types of glass were evaluated with the objective of finding a functional and economic material to build the photoreactor. It was found that Pyrex glass was the most suitable material to work with. As a UV light source to build the photoreactor, a dry gel nail lamp was used with 9 W, λ = 365 nm bulbs. On the other hand, the effects of different parameters (such as the catalyst mass (TiO₂ Degussa P-25), stirring speed (RPM), UV lamps, and temperature) over the photocatalysis reaction rate were analyzed. Also, the reaction's thermodynamic parameters were determined and found to be similar to those found in other investigations. Finally, the homogeneity in the distribution of TiO₂ particles inside the reactor when stirred at 475 rpm was verified using a COMSOL Multiphysics computer fluid dynamics simulation, which showed the theoretical trajectory of particles inside the reactor depending on the stirring rate of the reactor.

Simple and Competitive Adsorption Study of Nickel(II) and Chromium(III) on the Surface of the Brown Algae Durvillaea antarctica Biomass

In this work Ni(II) and Cr(III) adsorption on Durvillaea antarctica surface were studied, optimal condition of pH, adsorption time is achieved at pH 5.0, with contact times of 240 and 420 minutes for a maximum adsorption capacity of 32.85 and 102.72 mg g^-1 for Ni(II) and Cr(III), respectively. The changes in the vibration intensity of the functional groups detected in the starting material by Fourier transform infrared spectroscopy and the opening of the cavities after the biosorption process detected by scanning electron microscopy images suggested the interaction of the metal ions with the surface and the changes in the chemical behavior of the solid. The heavy metal adsorption equilibrium data fitted well to the Sips model. The effect of competitive ions on adsorption equilibrium was also evaluated, and the results showed that the two metals compete for the same active sites of the biosorbent; the increase of the Ni(II) initial concentration increases its adsorption capacity but decreases the adsorption capacity of Cr(III).

Dataset of the immersion enthalpy of activated carbons chemically modified in methylparaben aqueous solution: Relation with adsorption

Methylparaben (MePB) is a type of emerging contaminant [1], commonly present in wastewater and surface water, widely used as preservatives in personal care products. The risk associated with the presence of this pollutant in the environment is due to their classification as an endocrine disruptor [2]. Two activated carbons obtained from African palm shell (Elaeis Guineensis) modified chemically by impregnation with CaCl₂ (GC1) and MgCl₂ (GM1) at 1% wt/v and carbonized in CO₂ atmosphere at 1173 K, were prepared. The process of adsorption of methylparaben from aqueous solution to activated carbon is due to the interactions between the adsorbate and the adsorbent, which can be quantified through the determination of immersion enthalpies in aqueous solutions of MePB, finding values of - 22.45 and −45.23 J g⁻¹ for the immersion in the solution of 100 mg L⁻¹, -3.31 and −44.02 J g⁻¹ for the immersion in the solution of 200 mg L⁻¹ and -21.31 and −54.51 J g⁻¹, showing the highest values carbon GC1. To evaluate the efficiency of MePB adsorption on the obtained solids, Langmuir and Freundlich adsorption models were determined in order to relate the quantities adsorbed with the immersion enthalpies and know the intensity of the energy interactions between the MePB and the activated carbons.

Dataset for effect of pH on caffeine and diclofenac adsorption from aqueous solution onto fique bagasse biochars

Products of common use such as caffeine and diclofenac have been detected in surface water and groundwater, these molecules even at low concentrations have serious negative effects on animals and the environment, so they are becoming emerging contaminants. To remove pollutants from aqueous systems diverse adsorbents have been used, however materials obtained from agrochemical waste are a good alternative. This dataset present the adsorption of caffeine and diclofenac onto six fique bagasse biochars at different pH's, in addition information about textural, morphological and chemical properties of six samples of fique bagasse biochar using TGA, SEM, FTIR, PZC and Boehm's titration are provided.

Thermodynamic study of adsorption of nickel ions onto carbon aerogels

In this work, 8 samples of carbon aerogels with different ratios of catalyst versus resorcinol (R/C) from 25 to 1500 were used. The textural properties were evaluated from N₂ adsorption isotherms in 77 K, as well as the chemical ones, where the surface chemistry was evaluated through the Boehm titrations. The results were analyzed and related to the adsorption of the nickel (II) ion from aqueous solution. The experimental results show that the aerogel samples can be divided into two series with different properties: Series I, mainly microporous (low ratio R/C) and Series II (high ratio R/C) mainly microporous but with a contribution of mesoporosity. The specific surface area varied between 64 and 990 m² g^-1. The experimental results show that prepared aerogels have an adequate adsorption capacity towards nickel (II) ions. The behavior of the kinetics of Ni(II) adsorption on carbon aerogels adjusts in a better way the kinetic model of pseudo-second order since it is the one that presents the value of the highest R² correlation coefficient. The calorimetric data shows that the greater the area developed in carbons aerogels the enthalpy increases.

Caffeine Adsorption by Fique Bagasse Biochar Produced at Various Pyrolysis Temperatures

Biochar obtained from agricultural residues is ever more recognized as a multifunctional porous solid for multiples applications. In this study, fique bagasse biochars were produced at different temperatures and their corresponding deashing. These materials were investigated about physicochemical properties and adsorption capability of caffeine. The pH solution was an influential parameter, and it was determined that a pH =2.0 for washed biochar and pH= 6.0 for not washed biochar were the best conditions for adsorption. Langmuir, Freundlich and Redlich-Peterson isotherms models provided a good fit for the experimental data, indicating a surface and multi-layer adsorption. From the adsorption capacity at equilibrium of fique bagasse biochars it was concluded that pH-dependent interactions, hydrogen bonding and π- π stacking interaction were found to be responsible for caffeine adsorption. The results allow to visualize the biochar obtained from fique bagasse as a sustainable alternative for the waste derived from the production of the cabuya.

Data for the synthesis of pyrogallol-formaldehyde aerogels using two acid catalysts oxalic acid y hydrochloric acid

Aerogels are extremely porous materials with large pore volumes and low bulk densities. Their unique structure imparts extraordinary properties and wide applications. The synthesis of pyrogallol-formaldehyde xerogels has been reported using HClO₄ as a catalyst, but according to the literature review the synthesis of aerogels of these materials has not been documented. In the present work, the data for the synthesis of aerogels pyrogallol-formaldehyde are presented using oxalic acid and hydrochloric acid as catalysts. Also includes the data of the characterization of these materials by Infrared spectroscopy, thermogravimetric analysis Tg-DTG, Physisorption of N², Raman Spectroscopy, X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). It was determined that the use of these precursors of the synthesis of aerogels in acid medium, leads to the obtaining of microporous solids with a high value of the surface area, the material with the highest value of this parameter has been CAePF OA550 at have a BET area value of 1066 m² g⁻¹.

Influence of stacked structure of carbons modified on its surface on n-pentane adsorption

In this study, the microstructure of a series of activated carbons modified on its chemistry surface was evaluated from X-ray diffraction and porous structure analysis, and the effect of the stacked graphitic structure on the n-pentane adsorption capacity. The activated carbons were prepared modifying an activated carbon (obtained from coconut shell) by carbonization processes at 1073, 1173 and 1273 K and impregnation with 65% nitric acid solution, 60% phosphoric acid solution and reflux with 30% ammonium hydroxide solution. The activated carbons were characterized by N₂ adsorption at 77 K. It was found that these are essentially microporous materials with surface areas between 469 and 1113 m² g^-1, and the evaluation of the microstructure was performed by determining the number of aromatic layers stacked from the analysis of the observed diffraction peak between 20-30° 2θ which corresponds to the 002 reflection in the plane of the coal using the STACK XRD technical. The results showed that impregnation as carbonization favours the development of the crystalline structure to the activated carbons, which is shown by the increase of the stacked structure at the same time; this favours the n-pentane adsorption.

Mechanisms of Methylparaben Adsorption onto Activated Carbons: Removal Tests Supported by a Calorimetric Study of the Adsorbent⁻Adsorbate Interactions

: In this study, the mechanisms of methylparaben adsorption onto activated carbon (AC) are elucidated starting from equilibrium and thermodynamic data. Adsorption tests are carried out on three ACs with different surface chemistry, in different pH and ionic strength aqueous solutions. Experimental results show that the methylparaben adsorption capacity is slightly affected by pH changes, while it is significantly reduced in the presence of high ionic strength. In particular, methylparaben adsorption is directly dependent on the micropore volume of the ACs and the π- stacking interactions, the latter representing the main interaction mechanism of methylparaben adsorption from liquid phase. The equilibrium adsorption data are complemented with novel calorimetric data that allow calculation of the enthalpy change associated with the interactions between solvent-adsorbent, adsorbent-adsorbate and the contribution of the ester functional group (in the methylparaben structure) to the adsorbate⁻adsorbent interactions, in different pH and ionic strength conditions. It was determined that the interaction enthalpy of methylparaben-AC in water increases (absolute value) slightly with the basicity of the activated carbons, due to the formation of interactions with π- electrons and basic functional groups of ACs. The contribution of the ester group to the adsorbate-adsorbent interactions occurs only in the presence of phenol groups on AC by the formation of Brønsted⁻Lowry acid⁻base interactions.

Data of the immersion enthalpy of activated carbon in benzene and cyclohexane. Influence of the content of surface oxygenated groups

The objective of this data article is to show by calorimetric curves and the immersion enthalpies the differences between the interactions that occur when two activated carbons of different textural and chemical properties are put in contact with C₆ compounds (an aromatic and a closed chain aliphatic: benzene and cyclohexane, respectively) in their pure state, and subsequently in mixtures thereof, with different molar composition. The greatest interaction occurs with the activated carbon that has the lower content of oxygen groups on the surface, both for the pure solvents, as for the mixtures; As for wetting liquids, there is a greater interaction with benzene (−∆H_im: 94.98–106.40 J g⁻¹) than with cyclohexane (−∆H_im: 21.23–65.97 J g⁻¹). The immersion enthalpy values for the different molar fractions are between −36.51 and −79.69 J g⁻¹ for the oxidized sample, and between −50.43 and −85.59 J g⁻¹ for the sample without chemical modification.

Adsorción de acetaminofén sobre carbones activados a diferente pH. Entalpía y entropía del proceso

Se analizaron los cambios entálpicos y entrópicos derivados del proceso de adsorción de acetaminofén sobre carbones activados con química superficial modificada. Se realizó, además, una variación del pH para determinar los cambios en las propiedades termodinámicas cuando existen cargas en el adsorbato y en el adsorbente. Se encontró que la máxima capacidad de adsorción (1,172 mmoles g -1) corresponde al proceso llevado a cabo en el carbón activado denominado CAR en este estudio a pH 7; los valores de las funciones termodinámicas de entalpía de inmersión y entropía de adsorción fueron -36,02 J g-1 y 0,123 J g-1 K-1, respectivamente. Así, el cambio de entropía de adsorción para el acetaminofén en los carbones activados estudiados dependió del pH. Se encontró que esta función termodinámica varía en el siguiente orden pH 2 > pH 11 > pH 7. Este comportamiento se relaciona con el número de especies presentes en la solución capaces de interactuar con la superficie del carbón activado.  

Effect of textural and chemical characteristics of activated carbons on phenol adsorption in aqueous solutions

The effect of textural and chemical properties such as: surface area, pore volume and chemical groups content of the granular activated carbon and monoliths on phenol adsorption in aqueous solutions was studied. Granular activated carbon and monolith samples were produced by chemical activation. They were characterized by using N2 adsorption at 77 K, CO2 adsorption at 273 K, Boehm Titrations and immersion calorimetry in phenol solutions. Microporous materials with different pore size distribution, surface area between 516 and 1685 m2 g−1 and pore volumes between 0.24 and 0.58 cm3 g−1 were obtained. Phenol adsorption capacity of the activated carbon materials increased with increasing BET surface area and pore volume, and is favored by their surface functional groups that act as electron donors. Phenol adsorption capacities are in ranged between 73.5 and 389.4 mg · g−1.

Adsorption of CO2 onto Activated Carbons Prepared by Chemical Activation with Metallic Salts

Activated carbons are obtained by chemical activation of African Palm shells (Elaeis guineensis) with different impregnating agents, i. e. magnesium chloride (MgCl2) and calcium chloride (CaCl2) aqueous solutions at different concentrations (3, 5 and 7 % w/v) and temperatures (between 773 and 1073 K), in order to assess their influence on the development of the porosity. The activated carbons prepared are characterized in terms of both textural and chemical properties. The activated carbons have a surface area and a pore volume ranging between 19 and 501 m2.g−1 and 0.03–0.29 cm3.g−1, respectively. Based on the obtained results, the samples with higher surface area and pore volume (i. e. those impregnated with MgCl2 and CaCl2 solutions and thermally treated at 1073 K) are selected to evaluate the adsorption capacity and affinity for CO2. CO2 adsorption capacity varies between 1.78 and 2.95 mmolCO2.g−1 at 273 K and low pressure, and the activated carbon impregnated with the solution of MgCl2 3% and activated at 1073 K (i. e. ACMg3-1073) showed the best performances. Finally, the kinetic results show that adsorption rate for sample ACMg3-1073 is enhanced by its micro-mesoporous nature, being the access routes to the micropores larger.

Data for the synthesis of resorcinol-formaldehyde aerogels in acidic and basic media

The aim of this research is to synthesise carbon aerogels and to compare the differences in their textural, morphological and chemical properties when synthesised in basic and acidic media, and with two different types of pretreatment carbonization and activation with CO₂. Four samples are prepared and characterised using TGA–DTA, SEM, DRX, isotherm determination of N₂ adsorption–desorption at −196 °C and immersion calorimetry. The data for pore distribution are reported using non-local density functional theory and quenched solid density functional theory. Finally, with the immersion calorimetry data, the consistency between the results using this technique and those obtained using the nitrogen isotherms is analysed.

Calorimetric study of activated carbons impregnated with CaCl2

Activated carbon monoliths with different surface characteristics were prepared by impregnating oil palm stone with diluted aqueous CaCl

Vapour phase hydrogenation of phenol over rhodium on SBA-15 and SBA-16

In the present work, mesoporous SBA-15 and SBA-16 were synthesised using classical methods, and their physicochemical properties were investigated by X-ray diffraction (XRD), FTIR, TEM and N2 adsorption-desorption. Rhodium (Rh, 1 wt %) was loaded on the mesoporous SBA-15 and SBA-16 by an impregnation method. The Rh surface coverage, dispersion and crystallite size were determined by room temperature H2 chemisorption on reduced samples. The catalytic activity of Rh supported on mesoporous SBA-15 and SBA-16 was evaluated for the first time in the hydrogenation of phenol in vapour phase in a temperature range between 130 and 270 °C at atmospheric pressure. The reaction over Rh/SBA-15 at 180 °C produced cyclohexanone as the major product (about 60%) along with lower amounts of cyclohexanol (about 35%) and cyclohexane (about 15%). The influences of temperature, H2/phenol ratio, contact time and the nature of the solvent on the catalytic performance were systematically investigated. The Rh/SBA-16 system offered lower phenol conversion compared to Rh/SBA-15, but both have a very high selectivity for cyclohexanone (above 60%).