Type Isotherm Research Articles

Study on Optimum IUPAC Adsorption Isotherm Models Employing Sensitivity of Parameters for Rigorous Adsorption System Performance Evaluation

Adsorption cooling technologies driven by low-grade thermal or solar power are used as an energy-efficient alternative to conventional refrigeration and air conditioning systems. Explicit understanding of the adsorption cycles requires precise determination of the performance parameters, replication of the experimental data, and the rigorous study of the adsorption heat transformation method. Hence, the optimum adsorption isotherms model must be identified. Scientists often face difficulties in selecting the suitable isotherm model as there are many models for a particular form of adsorption isotherm. The present study introduces a novel approach for choosing the optimal models for each type of International Union of Pure and Applied Chemistry (IUPAC) classified adsorption isotherm using robust statistical methods. First, the box-and-whisker plots of error identification are employed. Tóth for Type-I(a) and Type-I(b), modified BET for Type-II, GAB for Type-III, Universal for Type-IV(a), and Type-IV(b), Sun Chakrabarty for Type-V, and Yahia et al. for Type-VI were found lower than the other candidate models in box-and-whisker plot. The optimality of our selected models was further verified using analysis of variance (ANOVA), pairwise Tukey honest significant difference (HSD) test, Kruskal–Wallis rank-sum test, and pairwise Wilcoxon rank-sum test. In short, rigorous statistical analysis was performed to identify the best model for each type of isotherm by minimizing error. Moreover, specific cooling effect (SCE) of Maxsorb III/ethanol and silica gel/water pairs were determined. Results showed that Tóth is the optimal isotherm model for the studied pairs, and the SCE values obtained from the model agree well with experimental data. The optimum isotherm model is indispensable for the precise designing of the next generation adsorption cooling cycles.

Adsorption modeling by two sites Langmuir type isotherm for adsorption of bisphenol-A and diethyl phthalate onto activated carbon in single and binary system

ABSTRACT Adsorption of bisphenol-A (BPA) and diethyl phthalate (DEP) onto activated carbon has been studied. The experimental adsorption data is reasonably well fitted by a two site Langmuir isotherm model. The estimated two equilibrium adsorption constants were almost the same even though the adsorbates were different. This suggested that the existence of two types of adsorption sites with different equilibrium adsorption constants for strong and weak sites on the present activated carbon surface. The equilibrium adsorption constant of strong site was 130 times larger than that of weak site, and the saturated adsorption density of weak site was 2.6 and 3.6 times larger than that of strong site for BPA and DEP, respectively. In addition, adsorption experiments of the binary system have also been carried out. Based on suggesting two type sites, two models, competitive adsorption or noncompetitive adsorption models, were attempted to apply to the experimental results. Judging from the model consideration, the noncompetitive model could describe well the adsorption isotherm in the binary system. Compared with the single system, in the binary system, the equilibrium adsorption constants were almost the same, but the saturated adsorption densities were 10% to 30% lower than that of the single system.

Experimental and Theoretical Studies of α-Linolenic Acid as Green Corrosion Inhibitor for Carbon Steel in 0.5 M Sulfuric Acid.

A component of Salvia hispanica, α-linolenic acid, has been evaluated as a green corrosion inhibitor for 1018 carbon steel in 0.5 M sulfuric acid using weight loss tests, potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) measurements. Theoretical calculations using Density Functional Theory (DFT) were used also. The results have shown that this compound is a good corrosion inhibitor, with an efficiency which increased with an increase in its concentration up to 600 ppm, but it decreased with a further increase in the concentration. α-linolenic acid formed protective corrosion products layer because it was chemically adsorbed onto the steel surface according to a Langmuir type of adsorption isotherms. Polarization curves have shown that α-linolenic acid is a good, mixed type of inhibitor with a predominant effect on the cathodic hydrogen evolution reactions. EIS measurements indicated a charge transfer-controlled corrosion process. DFT calculations indicated that α-linolenic acid was more efficient in an acidic environment than in a neutral one because has a high tendency to donate electrons and can be easily protonated. In addition to this, it had the highest EHUMO value, the best chemical reactivity, the greatest tendency to transfer electrons and a greater facility of modifying its electronic configuration in the presence of carbon steel specimens according to its chemical hardness value.

Protein Adsorbate Biohybrids and Sequential Hystallosteric Protein Adsorption

Abstract Protein adsorption on solid surfaces is characterized by multivalence, binding-unit overlap, sequential adsorption, surface allosterics, lateral interactions and pronounced adsorption-desorption hysteresis, giving rise to the sequential, hystallosteric, adsorption model ("SHA model"). Adsorption isotherms of fibrinogen on a titanium miniplates and of the growth factors rhBMP-2 and rhVEGF165 on PDLLA nanofiber fleeces are presented. Controversial Langmuir type isotherms of fibrinogen and rhVEGF165 can be understood on the basis of singular long-lived metastable states central to the SHA-model.

Comparative analysis of pore structure parameters of coal by using low pressure argon and nitrogen adsorption

The accurate characterization of coal pore structure is of great significance for in-depth understanding of interior properties and gas adsorption, desorption and diffusion characteristics. In this study, the low pressure argon adsorption (LP-ArGA) and low pressure nitrogen adsorption (LP-N2GA) were all used to analyze the pore parameters of coal with different metamorphism. The results indicated that the adsorption isotherm type and desorption hysteresis type of coal samples obtained by the LP-ArGA and LP-N2GA belong to the same type, but the adsorption capacity of the former is higher than that of the latter. The pore size distribution (PSD) of coal samples shows a significant multi-peak distribution feature. Compared with the LP-N2GA, the LP-ArGA can accurately analyze the pore parameters between 2 and 4 nm or part of 2–7 nm. The mesopore volumes obtained by the LP-ArGA is 1.66–2.84 times that of the LP-N2GA, and there is no obvious law of macropore volume. The macropore volumes of QN and PM samples decreased by 17.2% and 50.9%, respectively, while GHS sample increased by 166.0%. The corresponding specific surface area (SSA) showed the same properties. Fractal curve fitting results obtained by the two methods are highly correlated, but compared with LP-ArGA, D1 and D2 obtained by the LP-N2GA can well reflect pore characteristics. The fractal dimension obtained by the two methods and the variation trend with the metamorphic degree are all different, which is mainly due to the difference of adsorption volume. The purpose of this paper is to introduce a new method for the analysis of coal pore structure in order to better understand the pore characteristics.

Preparation of Soluble Complex of Curcumin for the Potential Antagonistic Effects on Human Colorectal Adenocarcinoma Cells

This study was designed to investigate the effects of curcumin (CMN) soluble complex (SC) prepared by melt casting (HM) and hot-melt extrusion (HME) technology. Phase solubility (PS) study, in silico molecular modeling, aqueous solubility, drug release, and physicochemical investigation including a novel dyeing test was performed to obtain an optimized complex by a central composite design (CCD). The results show that the HME-SC produces better improvements towards solubility (0.852 ± 0.02), dissolution (91.87 ± 0.21% at 30 min), with an ideal stability constant (309 and 377 M−1 at 25 and 37 °C, respectively) and exhibits AL type of isotherm indicating 1:1 stoichiometry. Intermolecular hydrogen bonding involves the formation of SC, which does not undergo any chemical modification, followed by the complete conversion of the amorphous form which was identified by XRD. The in vitro cytotoxicity showed that IC50 was achieved in the SW480 (72 µM.mL−1) and Caco-2 (40 µM.mL−1) cells while that of pure CMN ranged from 146 to 116 µM/mL−1. Apoptosis studies showed that cell death is primarily due to apoptosis, with a low rate of necrosis. In vivo toxicity, confirmed by the zebrafish model, exhibited the safety of the HME-SC. In conclusion, the HME-SC potentially enhances the solubility and cytotoxicity to the treatment of colorectal cancer (CRC).

Caffeine adsorptive performance and compatibility characteristics (Eisenia foetida Savigny) of agro-industrial residues potentially suitable for vermifilter beds

The caffeine adsorptive performance and compatibility characteristics (Eisenia foetida Savigny) of rice husk, peanut shell, corn cob and coconut fiber were studied, aiming to assess the suitability of these residues for vermifilter beds. For this purpose, the agro-industrial residues were characterized and the E. foetida Savigny compatibility was determined by acute and chronic toxicity tests. Batch adsorption tests were performed using caffeine solutions. Optimal adsorption conditions, kinetic models, isotherm type and the influence of three particle sizes (120–150, 300–600, 800–2000 μm) in the caffeine removal were determined. Coconut fiber (120–150 μm) proved to be the most efficient residue for the caffeine removal (94.2%), requiring 4 g/L for 30 min. However, coconut fiber was the less compatible for earthworms (14d-LC50 = 82%). The results obtained allow to define adequate strategies, such as mixing highly adsorptive residues with the more compatible ones, to choose the most effective materials for vermifiltration technologies.

Potassium Adsorption Phenomenon in Calcareous Soils of Shahrazur Plain


 
 
 
 A laboratory study for adsorption of potassium (K) determination was conducted on six soils located in Sharazur plain from the Kurdistan Region of Iraq in 2021 using the batch technique method. Potassium (K) adsorption isotherms were achieved by equilibrating 5.0 g of soil samples with eight grades of K (0 to 300 mg L-1) as KCl in 50 ml of 0.01M CaCl2 solution. To match the data of adsorption, Freundlich, Langmuir, and Temkin adsorption isotherms were used. The results show that the amount of adsorbed K ranged between (45.78 to 52.49) % added K. The Freundlich model fit the equilibrium K adsorption data better for the Serwan location of soil (silty loam), as demonstrated by a greater coefficient of determination (R2 =0.90). The value of heterogeneity factor 1/n for the Freundlich model ranged from (0.34 to 0.47) kg mg-1, which was less than one. The sorption processes for all of the studied soils were normal adsorption. The constant of the Langmuir isotherm (KL) aligned from (0.107 to o.425) L mg-1. Smaller KL values mean that more adsorbed K would be transformed to a non-exchangeable form, either through the creation of crystalline K or through ion occultation. The RL values indicate the type of isotherm, the values of RL> 1 that means the adsorption nature to be unfavorable. The Temkin equilibrium binding constant (AT) was high for all studied soils except the soils of Bestan Sur and Grdigo locations, the high value of AT indicates high binding energy. The Temkin constant (bT) ranged from (10.46 to 13.47) J mole-1 that was related to the nature of the adsorption energy, a positive value indicates that the adsorption process is exothermic.
 
 
 
 

Aza-18-crown-6 modifiye karbon nanotüplerin sentezi, karakterizasyonu ve adsorpsiyon kapasitesinin belirlenmesi

Karbon nanotüpler (CNT) olağanüstü eşsiz özellikleri sebebiyle keşfinden günümüze birçok uygulama alanı bulmuştur. Yüzeylerinde gerçekleştirilen kovalent modifikasyonlarla kimyasal ve fiziksel özellikleri geliştirilebilmektedir. Bu çalışma ile 1-aza-18-crown-6 modifiye karbon nanotüpler Steglich esterleşmesi ile sentezlenmiştir. Sentezlenen bileşik FTIR, 1H-NMR, 13C-NMR, TGA ve TEM yöntemleriyle karakterize edilmiştir. Elde edilen bileşiğin ve modifiye edilmemiş CNT bileşiğinin Fe3+, Mn2+, Co2+, Cr3+, Cu2+, Zn2+ metal iyonlarını adsobsiyonu incelenmiştir. Adsorpsiyon yüzdesi (% A.Y.), adsorpsiyon kapasitesi (qe), maksimum adsorpsiyon kapasitesi (qmax), adsorpsiyon denge sabiti (Kd), Serbest Gibbs Enerjisi (ΔGo) ve izoterm türü belirlenmiştir. Adsorpsiyon çalışmalarına göre, monoaza-18-crown-6 modifiye edilmiş çok duvarlı karbon nanotüp (MWCNT-CO-(MA-18-Crown-6)) bileşiği, tüm metal iyonlarını ham çok duvarlı karbon nanotüpten (MWCNT) çok daha iyi yüzdelerde adsorbe ettiği gözlenmiştir. MWCNT-CO-(MA-18-Crown-6) bileşiği, çözelti içindeki Fe3+ iyonlarının yaklaşık olarak tamamını (% 96.15) adsorbe etmiştir. Bu sonuçlar ışığında elde edilen MWCNT-CO-(MA-18-Crown-6) bileşiği metal iyonlarının sulu ortamlardan adsorpsiyonunda başarılı bir şekilde uygulanabileceği söylenebilir.

The Study of Sorption Characteristics of Dried Crab Stick Product Using Dynamic Vapor Sorption

The research delved into the sorption characteristics of dried crab stick products using dynamic vapor sorption (DVS). The obtained sorption isotherm data, including equilibrium moisture content (Me) and water activity (aw), were fitted with 6 different sorption isotherm models, such as Brunauer-Emmett-Teller (BET), Guggenheim-Anderson-Boer (GAB), Pickett-Modified BET, Adam and Shove, Blahovec-Yanniotis, and Peleg. The results showed that the Peleg model was the best-describing model with a coefficient of determination (R2), chi-square (χ2), root mean square error (RMSE), and standard error of estimate (SEE) ranging from 0.988 to 0.998, 0.719 to 4.349, 0.431 to 2.609 and 0.692 to 1.703, respectively. According to the classification of the shape of moisture sorption isotherm, the isotherm type III and II were found in this research for adsorption and desorption, respectively. The GAB and BET models were used to estimate monolayer moisture content (M0) of the sample and it was found that the M0 ranged from 3.65 to 5.36 % dry basis and 4.57 to 4.83 % dry basis for GAB and BET models, respectively. Blahovec-Yanniotis’s model was applied in this work to investigate the contribution of water and the result showed that the contribution of solution water played a major in the moisture changes of the sample during the adsorption and desorption process. Moreover, sorption isotherm data were modeled with 0 and 1st order reaction kinetics, and the results demonstrated that 0 order and 1st order models were the most appropriate model to describe moisture changes behavior of the sample at each relative humidity step for adsorption and desorption, respectively.
 HIGHLIGHTS
 
 The construction of sorption isotherms of dried crab stick product using dynamic vapor sorption
 GAB and BET models were used to estimate monolayer moisture content
 Peleg model was the most appropriate model to describe sorption behaviors of dried crab stick product
 Blahovec-Yanniotis provided the contribution of water information of dried crab stick during adsorption and desorption processes
 The application of reaction order kinetics could provide the information of moisture changing behaviors at each relative humidity step for adsorption and desorption processes
 
 GRAPHICAL ABSTRACT

Multicomponent oxide composites for carriers in catalytic applications

AbstractBinary, ternary, and quaternary composite oxides of rare earths (La and Ce) with one or more of aluminum, magnesium, and zirconium, prepared by coprecipitation are studied. Potential use is carrier in steam or dry reforming of hydrocarbons and ethanol. Individual components influence specific surface area, porosity, acidity, hydrothermal stability, and oxygen storage capacity (OSC) differently. Interaction effects between components further influence these properties resulting in unexpected trends. Alumina and magnesia form solid solutions with zirconia until 650℃. Magnesia imparts better hydrothermal stability to zirconia. Aluminum and magnesium form MgAl2O4 spinel in ternary composites. Specific surface area varies linearly with alumina content. Alumina influences porosity, whereas magnesia influences pore diameter. The composites are mesoporous. Only binary composites present unimodal, pore size distribution. Composites containing alumina present type H2 isotherms while the remaining composites present H3 type isotherms. OSC increases over ZrO2/CeO2 5.7 to 15.3 molar. Magnesia and alumina affect microstructure and hydrothermal stability in contrasting ways. Thermogravimetry indicates that ternary composites of zirconia with alumina or magnesia form through oxolation. Surface hydroxyls with varying acidity are seen by FTIR in as synthesized samples. Magnesia and zirconia influence acidity in opposite ways, which impacts deactivation in the decomposition of 2‐methyl‐3‐butyn‐2‐ol.

Facile synthesis of silica‐polymer monoliths using nonionic triblock copolymer surfactant for efficient removal of radioactive pollutants from contaminated seawater

AbstractHere, we introduce a highly porous functional mesoscopically silica‐polymer composite based on silica monolith‐conjugated thiourea/formaldehyde copolymer. The developed nanostructure enables selective and fast removal of the radioactive pollutants strontium (Sr[II]) and cesium (Cs[I]) ions from contaminated seawater. The silica/polymer composite was synthesized by introducing thiourea/formaldehyde solution into tetramethoxy orthosilicate/triblock copolymer emulsion. The chemical and textural features of the synthesized silica/thiourea‐formaldehyde polymer composite (SiO2‐TUF) were characterized using Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, scanning electron microscope, high‐resolution transmission electron microscope, energy dispersive X‐ray analysis, dynamic light scattering, thermal analysis, and N2 adsorption/desorption measurements. The synthesized microporous SiO2‐TUF showed excellent cesium and strontium ions removal ability, reaching a maximum adsorption capacity of 78.2 and 40.3 mg g−1 for Sr(II) and Cs(I), respectively. When tested with seawater contaminated with radioactive cesium and strontium, SiO2‐TUF was able to selectively target Sr(II) and Cs(I) ions. Among the different types of adsorption isotherms investigated, Sips isotherm showed the best fit with R2 > 0.990. The kinetic studies showed that the pseudo‐second‐order model gave the best description of the uptake process.

Synthesis of porous silicon based nanoparticles for applications in surface enhanced Raman spectroscopy

In this work porous Si (PSi) nanoparticles (NPs) were prepared by magnesiothermic reduction of the synthesized SiO2 spheres, and Ag NPs were deposited on the PSi with formaldehyde or HF. In addition, silver NPs were deposited on the porous Si obtained by milling and etching the Si wafer. Silver NPs on SiO2 spheres and particles with Ag core and mesoporous SiO2 shell were also synthesized. SEM analysis showed the Ag NPs size distributions between 30.1 and 64.3 nm. The synthesized samples were quite stable in aqueous media and had zeta potential between −11.5 and −44.3 mV. The samples exhibited reversible physisorption isotherms of type II except for the sample with Ag core and SiO2 (Ag–S) coating, which exhibited a type IVa isotherm accompanied by the hysteresis characteristic of mesoporous adsorbents. The BET surface areas of the samples ranged from 9 to 56 m2g-1, with the mesoporous Ag–S sample having the largest surface area of 378 m2g-1. The surface enhanced Raman spectroscopy (SERS) performance of the synthesized samples was studied by analysing the detection limit of 4-mercaptophenylboronic acid (4-MPBA) as a probe molecule at 532 nm laser excitation. The lowest limit of detection of 1 × 10−5 mol dm−3 was obtained with the sample in which silver NPs were deposited on silica spheres (S–Ag).

Removal of 3-chloroaniline from aqueous solution by treated coffee waste: isotherm modelling and thermodynamic studies

ABSTRACT 3-chloroaniline (3CA) concentrations were measured in aqueous solution by UV/Vis spectrophotometer. Validation of the calibration curve’s linearity, instrumental precision (RSD%), limits of detection and quantification were accomplished. The coefficient of calibration curve (1.0–10.0 mgL−1 3CA) had a high correlation (R2 = 0.9997) and the instrumental precision was in the range (RSD% = 0.50–0.74%, n = 10). The LOD and LOQ from the regression analysis were 0.20 mgL−1 and 0.61 mgL−1, respectively. A treated coffee waste adsorbent was utilised for 3-chloroaniline removal by process of sorption from aqueous solution. The major components of the coffee waste are the hemicellulose, cellulose, and lignin. The temperature effect (25°C, 35°C and 45°C) on sorption was evaluated, with sorption decreasing by increasing of temperature which reached 87%, 75% and 54%, respectively. Isotherms type L were found and associated with monolayer sorption. The parameters of sorption were examined by employing Langmuir, Freundlich and Dubinin-Radushkevich sorption models. The isotherm models of Langmuir and Dubinin-Radushkevich had acceptable correlation coefficients (R2 = 0.87–0.88). The Langmuir and Dubinin-Radushkevich sorption capacities of 3-chloroaniline were found to be 44 to 50 mgg−1. The values of separation factor (RL) were ranging from (0–1) which indicated a favourable sorption. In thermodynamic study the physical sorption process was confirmed by van’t Hoff equation. In addition, the free energy ∆G° (−19.1 kJmol−1) and enthalpy ∆H° (−56.6 kJmol−1) had negative values which suggested that the sorption was spontaneous, and the process was exothermic.

Parametric Analysis of Two-dimensional Equation of State used to Predict High Pressure CO2 and CH4 on NaY zeolite and babassu activated carbon

In this work, the potential of two-dimensional equations of state (2D) was explored in terms of high pressure adsorption prediction and parametric analysis. To attain this objective, firstly, low pressure experimental data for CO2 and CH4 adsorption on NaY zeolite and babassu activated carbon were correlated with two-dimensional equations of state of van der Waals (2D vdW), Peng-Robinson (2D PR), Zhou et al. (2D ZGR) and 2D ZGRm (m as a fitted paramter). Then, high pressure isotherms were predicted for the same systems and compared to experimental data. Thus, a parametric analysis was made varying 2D ZGRm parameters: adsorbate-adsorbate interaction (a2); co-area (b2); Henry's Law constant (K); heterogeneity parameter (m); adsorbent specific area (A). Results indicate that these parameters present a critical value at a given pressure that separates homogeneous and heterogeneous adsorbed phases. Depending on the set of parameters applied, different types of isotherms can be described by 2D ZGRm. Therefore, it was verified that 2D EOS have the potential to be applied for both low pressure characterization of adsorbent materials and high-pressure adsorption processes.

Measurement and interpretation of unary supercritical gas adsorption isotherms in micro-mesoporous solids

Gas adsorption at high pressures in porous solids is commonly quantified in terms of the excess amount adsorbed. Despite the wide spectrum of adsorbent morphologies available, the analysis of excess adsorption isotherms has mostly focused on microporous materials and the role of mesoporosity remains largely unexplored. Here, we present supercritical CO2 adsorption isotherms measured at T=308 K in the pressure range p=0.02{-}21 MPa on three adsorbents with distinct fractions of microporosity, phi_2, namely a microporous metal-organic framework (phi_2=70%), a micro-mesoporous zeolite (phi_2=38%) and a mesoporous carbon (phi_2<0.1%). The results are compared systematically in terms of excess and net adsorption relative to two distinct reference states–the space filled with gas in the presence/absence of adsorbent–that are defined from two separate experiments using helium as the probing gas. We discuss the inherent difficulties in extracting from the supercritical adsorption isotherms quantitative information on the properties of the adsorbed phase (its density or volume), because of the nonuniform distribution of the latter within and across the different classes of pore sizes. Yet, the data clearly reveal pore-size dependent adsorption behaviour, which can be used to identify characteristic types of isotherm and to complement the information obtained using the more traditional textural analysis by physisorption.

Single and Competitive Adsorption Behaviors of Cu2+, Pb2+ and Zn2+ on the Biochar and Magnetic Biochar of Pomelo Peel in Aqueous Solution

As an environment-friendly material, biochar has been used to remove heavy metals from wastewater, and the development of cost-effective biochar has been an emerging trend. However, limited studies consider the competitive adsorption of co-existing metals and the separation efficiency of absorbent and solution after adsorption. In this study, pomelo peel was used to prepare biochar (BC) and magnetic biochar (MBC) at different temperatures. Then, the physicochemical properties of the biochars were characterized and the adsorption characteristics of Cu2+, Pb2+, and Zn2+ on the biochars in single, binary, and ternary metal systems were investigated. The results showed that both pyrolysis temperature and magnetization could affect the adsorption capacity of biochar. The adsorption kinetic and thermodynamic processes could be well described by the pseudo-second-order kinetic model and Langmuir model. The adsorption isotherm types of Pb2+ and Zn2+ changed in the binary metal condition. The competitive adsorption order of three heavy metal ions in ternary metal adsorption was Pb2+ &gt; Cu2+ &gt; Zn2+. The MBC of 500 °C showed a good adsorption capacity to Pb2+ in the co-existing environment, and the maximum adsorption capacity was 48.74 mmol g−1. This study also provided technical support for the utilization of pomelo peel and the engineering application of biochar.

Nanometer Pore Structure Characterization of Taiyuan Formation Shale in the Lin-Xing Area Based on Nitrogen Adsorption Experiments

Ordos Basin is an important continental shale gas exploration site in China. The micropore structure of the shale reservoir is of great importance for shale gas evaluation. The Taiyuan Formation of the lower Permian is the main exploration interval for this area. To examine the nanometer pore structures in the Taiyuan Formation shale reservoirs in the Lin-Xing area, Northern Shaanxi, the microscopic pore structure characteristics were analyzed via nitrogen adsorption experiments. The pore structure parameters, such as specific surface area, pore volume, and aperture distribution, of shale were calculated; the significance of the pore structure for shale gas storage was analyzed; and the main controlling factors of pore development were assessed. The results indicated the surface area and hole volume of the shale sample to be 0.141–2.188 m2/g and 0.001398–0.008718 cm3/g, respectively. According to the IUPAC (International Union of Pure and Applied Chemistry) classification, mesopores and macropores were dominant in the pore structure, with the presence of a certain number of micropores. The adsorption curves were similar to the standard IV (a)-type isotherm line, and the hysteresis loop type was mainly similar to H3 and H4 types, indicating that most pores are dominated by open type pores, such as parallel plate-shaped pores and wedge-shaped slit pores. The micropores and mesopores provide the vast majority of the specific surface area, functioning as the main area for the adsorption of gas in the shale. The mesopores and macropores provide the vast majority of the pore volume, functioning as the main storage areas for the gas in the shale. Total organic carbon had no notable linear correlation with the total pore volume and the specific surface area. Vitrinite reflectance (Ro) had no notable correlation with the specific surface area, but did have a low “U” curve correlation with the total pore volume. There was no relationship between the quartz content and specific surface area and total pore volume. In addition, there was no notable correlation between the clay mineral content and total specific surface area and total pore volume.

Total Oxidation of Isopropanol in Its Liquid Phase, at a Low Temperature in the Presence of Prepared and Characterized Zinc Oxide

The complete oxidation of isopropanol in its liquid phase at a low temperature was studied in the presence of zinc oxide (ZnO). This solid was prepared with the precipitation method. Structural analysis (infrared in Fourier transform and diffraction of X-rays) and textured (adsorption/desorption of N2) were conducted for the wurtzite structure results, an IV type isotherm with a type H3 hysteresis. This solid presents a good catalytic activity against the complete oxidation of isopropanol, a constant of selectivity equal to 1; however, the studied temperatures were 40, 60, and 80°C. In addition, a kinetic study of the oxidation was performed and showed that the reaction follows a successive mechanism isopropanol-acetone-carbon dioxide. The low value of the apparent energy of the activation of this solid confirms the high value of the initial rate of the catalytic oxidation reaction of isopropanol in the temperature range studied.

Enhancing methylene blue sorption on spotted golden thistle stalks by soft chemical pretreatments

Soft chemical treatments of dried stalks of the spotted golden thistle yielded novel sorbents; both the stiff nature and mass of the raw material were preserved. For minimal environment impact, the solution concentrations of the tested reagents were optimized at ambient temperature. The sorbents obtained were tested for the removal of methylene blue. The approach used kinetics and equilibrium studies. NaOH (0.1 mol L−1) treatment was efficient and afforded two new materials with seriously improved sorption features: the equilibrium time was reduced from 17–19 h to 10–12 h whilst, maximal sorption capacity increases from 65 to 100 and 112 mg g−1 i.e., enhancements of 54 and 72%. The Avrami model followed by the pseudo second-order model, best fitted the kinetic data. The isotherms were of Hmx type and were satisfactorily fitted to the Redlich-Peterson model. The Langmuir, Tóth, and Sips models were suitable to describe the H type isotherms relating to limited data ranges. Microanalysis, scanning electron microscopy (SEM), SEM coupled to energy dispersive X-ray, and attenuated total reflectance infrared spectroscopy showed an increase of the lignocellulosic content and the strengthening of the interactions between the dye and the sorbent. However, zeta potential measurements showed that the charge of the surface became almost inexistent after the pretreatment.