Apparent Activation Energy Of Adsorption Research Articles

Ultra-high temperature suspending stabilizer and cement slurry interface interaction law and mechanism study for ultra-deep well cementing

The high temperature issue that cementing is facing is getting more and more significant as oil and gas extraction is being expanded to deep stratum. In order to increase the sedimentation stability of cement slurry under ultra-high temperature conditions, a suspension stability of cement slurry was created in the study. On the basis of previous research, its mechanism of action was examined from the perspective of interface interaction. The suspension stabilizer's low temperature adsorption behavior was investigated using the Zeta potential test and the total organic carbon (TOC) test. The findings indicate that the suspension stabilizer's apparent adsorption activation energy is 44.667 kJ/mol, which is in the range of chemical adsorption. The XRD test, infrared spectrum test, and Raman spectrum test were used to examine the cement's hydration byproducts. The findings demonstrate that hydrated calcium silicate (C-S-H) is the predominant component of the cement paste's short-term hydration products during ultra-high temperature curing. Ion concentration testing and molecular dynamics modeling were used to examine the interface interaction mechanism between the suspension stabilizer and the hydration products. The findings indicated that a network of chemical interactions, including hydrogen and ionic bonds, interacted between suspension stabilizer and C-S-H. The sedimentation stability of cement slurry is maintained by the persistence of these chemical linkages at extremely high temperatures.

Adsorption of Congo Red from Aqueous Solution Using La/MFA Composite as Adsorbent

A novel lanthanum/modified fly ash (La/MFA) composite adsorbent prepared by simple solution reaction was used for the adsorption of Congo Red (CR) dye from aqueous solution. The morphology and particle size distribution of the composite were characterized, and the equilibrium adsorption was researched. The results show that the adsorption of CR onto La/MFA can reach equilibrium in 30 minutes. The entire adsorption process can be well described by pseudo-second-order kinetic equation at different temperatures. The value of apparent adsorption activation energy is 16.2kJ/mol. The isothermal data conform to the Langmuir model with the maximum adsorption capacity of 714 mg/g at 298K. According to the negative values of Gibbs free energy change (ΔG°) and enthalpy change (ΔH°), and reduction of Langmuir adsorption coefficient with the increase of temperature, the adsorption system from 298K to 328K is confirmed to be of spontaneous and exothermic nature. The results of SEM and particle size analysis indicate that the particle sizes and specific surface of La/MFA are smaller and coarser than those of FA. As a low-value composite adsorbent, La/MFA is especially effective for the removal of high concentration CR.

A soil-column gas chromatography (SCGC) approach to explore the thermal desorption behavior of hydrocarbons from soils.

A soil-column gas chromatography approach was developed to simulate the mass transfer process of hydrocarbons between gas and soil during thermally enhanced soil vapor extraction (T-SVE). Four kinds of hydrocarbons-methylbenzene, n-hexane, n-decane, and n-tetradecane-were flowed by nitrogen gas. The retention factor k' and the tailing factor T f were calculated to reflect the desorption velocities of fast and slow desorption fractions, respectively. The results clearly indicated two different mechanisms on the thermal desorption behaviors of fast and slow desorption fractions. The desorption velocity of fast desorption fraction was an exponential function of the reciprocal of soil absolute temperature and inversely correlated with hydrocarbon's boiling point, whereas the desorption velocity of slow desorption fraction was an inverse proportional function of soil absolute temperature, and inversely proportional to the log K OW value of the hydrocarbons. The higher activation energy of adsorption was found on loamy soil with higher organic content. The increase of carrier gas flow rate led to a reduction in the apparent activation energy of adsorption of slow desorption fraction, and thus desorption efficiency was significantly enhanced. The obtained results are of practical interest for the design of high-efficiency T-SVE system and may be used to predict the remediation time.

Kinetic and Thermodynamic Studies of the Adsorption of Crystal Violet onto Used Black Tea Leaves

This study presents the kinetic and thermodynamic investigation of the adsorption of crystal violet (CV) on used black tea leaves (UBTL) from aqueous solution to evaluate the feasibility of the process. The effects of concentration, solution pH and temperature on adsorption kinetics were carried out in batch process. Kinetic studies have shown that the adsorption data partially follow simple first order, second order and pseudo second order kinetic equations for different initial concentrations at pH 2.0. The equilibrium amount adsorbed, equilibrium concentration and rate constant were calculated from better fitted pseudo second order kinetic plots for different initial concentrations. The equilibrium amount adsorbed (200 mg/g at 30 o C) increased with the increase of temperature, indicated endothermic nature of the adsorption. The apparent activation energy of adsorption was determined from Arrhenius plot using pseudo second order rate constant and the value, Ea = 83.1 kJ/mol, revealed the process is chemisorption. Thermodynamic parameters: DHo, DGo and DSo, were determined from the equilibrium adsorption constant and the results obtained confirmed that the adsorption process was feasible, less spontaneous and endothermic. The equilibrium amount adsorbed was found to be increased with increase of solution pH from 2.0 to 6.0 indicating electrostatic interaction between cationic CV with anionic surface of UBTL dominated at higher pH due to the low zero point charge of pH of UBTL.

The Adsorption Behavior of Modified Peanut Shells for Cr (VI)

The adsorption of Cr(VI) by modified peanut shell has been investigated using chemical methods and IR spectrometry. The optimal condition for the adsorption of Cr(VI) by modified peanut shell is at 308 K and pH = 1.0, which gives a static saturated adsorption capacity of 14.15 mg·g-1, an apparent adsorption rate constant of k298 = 2.43 × 10-4 s-1, and an apparent adsorption activation energy of 10.58 kJ·mol-1. The adsorption follows the Langmuir and Freundlich isotherms and the liquid film diffusion is the controlling process of the adsorption. The adsorption thermodynamic parameters are ΔH = 125.58 kJ·mol-1, ΔS = 0.473 9 kJ·mol-1·K-1, ΔG = -17.81– -27.27 kJ·mol-1. Small amount of desorption is observed only at pH > 11. Adsorption mechanism of modified peanut shells for Cr(VI) was both physical adsorption and chemical adsorption of adsorbent "adsorption-oxidation and reduction processes".

Evaluation of the Adsorption of Cr(VI) by Modified Bamboo Shells

The adsorption of Cr(VI) by modified Bamboo shell has been investigated using chemical methods and IR spectrometry. The optimal condition for the adsorption of Cr(VI) by modified Bamboo shell is at 298 K and pH = 1.0, which gives a static saturated adsorption capacity of 12.68 mg·g-1, an apparent adsorption rate constant of k298 = 9.56 × 10-4 s-1, and an apparent adsorption activation energy of 7.38 kJ·mol-1. The adsorption follows the Langmuir and Freundlich isotherms and the liquid film diffusion is the controlling process of the adsorption. The adsorption thermodynamic parameters are ΔH = 66.04 kJ·mol-1, ΔS = 0.2974 kJ·mol-1·K-1, ΔG = −22.58~−28.52 kJ·mol-1. The anions HPO42-, H2PO4- and SO42- have negligible influence on the adsorption capacity. Small amount of desorption is observed only at pH > 11. The adsorption of Cr(VI) by modified bamboo shell is mainly a chemical process.

Corrosion Control of Aluminium Alloy in Alkaline Solution Using Some Leave Extracts

The effect of Euphorbia hirta and Dialum guineense leave extracts on the corrosion of aluminium in 0.25M NaOH was investigated using gravimetric technique. It was shown that the presence of Euphorbia hirta and Dialum guineense leave extracts inhibited the corrosion of aluminium in the test solutions and that the inhibition efficiency depended on the concentration of the plant extract as well as on the time of exposure of the aluminium samples in 0.25M NaOH solu- tions containing the extracts. Dialum guineense extract shows the best inhibition capability for aluminium corrosion in so- dium hydroxide, probably, this is due to the planer orientation of the adsorbed extract molecules. Inhibition efficiency of the inhibitors tested increases with decreasing sodium hydroxide concentrations. The experimental data complied to both Langmuir and Temkin adsorption isotherms and the value and sign of the apparent activation energy of adsorption obtained suggests that inhibitor molecules have mixed inhibition mechanism.

Selective adsorption of Pt ions from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion exchange resin Diaion WA21J

Thermodynamic and kinetics studies for adsorption of Pt ions complexes from the chloride solutions obtained by leaching chlorinated spent automotive catalysts on anionic exchange resin Diaion WA21J were carried out. It was found that only Si, Pt, Rh and Pd from the solution were selectively adsorbed on the resin Diaion WA21J more strongly. The adsorption equilibrium time for Pt ions was about 20h. The isothermal adsorption of Pt ions was found to fit Langmuir, Freundlich and DKR models. The maximum monolayer adsorption capacities Qmax and Xm of Pt ions on the resin based on Langmuir and DKR model were 4.85, 5.36 and 5.69mg/g as well as 5.01, 5.63 and 5.98mg/g for temperatures 18°C, 28°C and 40°C, respectively. The apparent adsorption energy Ead based on DKR model were −11.79, −11.04 and −11.04kJ/mol for the temperatures 18°C, 28°C and 40°C, respectively. Ion exchange was the mechanism involved in the adsorption process. The adsorption of Pt ions on the resin underwent pseudo-first-order kinetic process, and the apparent adsorption activation energy Ea,1 was 12.6kJ/mol. The intraparticle diffusion of Pt ions was a main rate-controlling step in most of time of adsorption process.

Kinetic and Thermodynamic Studies on the Adsorption of Zn2+ onto Chitosan-aluminium Oxide Composite Material

This study presents kinetic and thermodynamic studies on the adsorption of Zn2+ onto chitosan-aluminium oxidecomposite material. The adsorption of Zn2+ onto chitosan-aluminium oxide composite material was found to followpseudo-second-order kinetic model and the apparent adsorption activation energy (Ea) was measured to be37.20kJ/mol. Adsorption was mainly chemical adsorption. Thermodynamic data supported Langmuir adsorptionmodel and the enthalpy of adsorption (ΔHθ) and the entropy of adsorption (ΔSθ) were found to be 17.81kJ/mol and109.77J/(mol?K), respectively. The adsorption Gibbs free energy (ΔGθ) decreased with the increase of temperature.

Adsorption Kinetics of Methylene Blue from Aqueous Solutions onto Palygorskite

The adsorption kinetics of methylene blue from aqueous solutions on purified palygorskite was investigated. The kinetics data related to the adsorption of methylene blue from aqueous solutions are in good agreement with the pseudo-second order equation in ranges of initial concentration of 120-210 mg/L, oscillation speed of 100-200 r/min and temperature of 298-328K. The experimental results show that methylene blue is only adsorbed onto the external surface of purified palygorskite, and the apparent adsorption activation energy is 13.92 kJ/mol. The relatively low apparent adsorption activation energy suggests that the adsorption of methylene blue involves in not only a chemical, but also a physical adsorption process, and it is controlled by the combination of chemical adsorption and liquid-film diffusion.

Adsorption of Pd(II) complexes from chloride solutions obtained by leaching chlorinated spent automotive catalysts on ion exchange resin Diaion WA21J

It was found that Rh, Pd and Pt contained in the spent ceramic automotive catalysts could be effectively extracted by dry chlorination with chlorine. In order to concentrate Pd(II) contained in the chloride solution obtained from the dry chlorination process, thermodynamic and kinetics studies for adsorption of Pd(II) complexes from the chloride solutions on anionic exchange resin Diaion WA21J were carried out. It was found that Pd, Pt, Rh, Al, Fe, Si, Zn and Pb from the chloride solution could be adsorbed on the resin. The isothermal adsorption of Pd(II) was found to fit Freundlich, Langmuir and Dubinin–Kaganer–Radushkevich models under the adsorption conditions. The adsorption of Pd(II) on the resin was favorable according to the values of 1/ n and R L from Freundlich and Langmuir adsorption isotherms, respectively. The maximum monolayer adsorption capacities Q max based on Langmuir adsorption isotherms were 5.70, 4.84 and 4.05 mg/g and the corresponding value X m based on Dubinin–Kaganer–Radushkevich were 5.55, 4.69 and 4.01 mg/g at temperatures 18 °C, 28 °C and 40 °C, respectively. The apparent adsorption energies ( E ad ) based on Dubinin–Kaganer–Radushkevich isotherm were −15.43, −16.22 and −23.57 kJ/mol for the temperatures 18 °C, 28 °C and 40 °C, respectively. Chemical adsorption was a main mechanism involved in the adsorption process. Pd(II) adsorption on the resin could be accelerated by increasing the adsorption temperature. The adsorption of Pd(II) from the chloride solution on the resin underwent pseudo-first order kinetic process and the apparent adsorption activation energy E a was 15.0 kJ/mol. The intra-particle diffusion was a main rate controlling step in the Pd(II) adsorption process under the adsorption conditions.

Kinetics of adsorption of Saccharomyces cerevisiae mandelated dehydrogenase on magnetic Fe3O4–chitosan nanoparticles

The adsorption of Saccharomyces cerevisiae mandelated dehydrogenase (SCMD) protein on the surface-modified magnetic nanoparticles coated with chitosan was studied in a batch adsorption system. Functionalization of surface-modified magnetic particles was performed by the covalent binding of chitosan onto the surface of magnetic Fe 3 O 4 nanoparticles. Characterization of these particles was carried out using FTIR spectra, transmission electron micrography (TEM), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). Magnetic measurement revealed that the magnetic Fe 3 O 4 –chitosan nanoparticles were superparamagnetic and the saturation magnetization was about 37.3 emu g −1 . The adsorption capacities and rates of SCMD protein onto the magnetic Fe 3 O 4 –chitosan nanoparticles were evaluated. The adsorption capacity was influenced by pH, and it reached a maximum value around pH 8.0. The adsorption capacity increased with the increase in temperature. The adsorption isothermal data could be well interpreted by the Freundlich isotherm model. The kinetic experimental data properly correlated with the first-order kinetic model, which indicated that the reaction is the adsorption control step. The apparent adsorption activation energy was 27.62 kJ mol −1 and the first-order constant for SCMD protein was 0.01254 min −1 at 293 K.

Adsorption behavior and mechanism of D113 resin for lanthanum

The sorption properties of macroporous weak acid resin (D113) for La 3+ ion were studied by chemical analysis and IR spectra. Experimental results indicate that the D113 resin has a good adsorption ability for La 3+ at pH = 6.0 in the HAc-NaAc medium. The statically saturated adsorption capacity is 273.3 mg/g. Separation coefficients of β La 3+/Ce 3+, β La 3+/Gd 3+, β La 3+/Er 3+, and β La 3+/Y 3+ are 2.29, 3.64, 4.27, and 0.627, respectively. The apparent activation energy of adsorption, E a is 18.4 kJ/mol, the thermodynamics parameters ΔH, ΔS, and ΔG of sorption are 4.53 kJ/mol, 61.8 J/(mol.K), −13.9 kJ/mol, respectively. The adsorption behavior of D113 for La 3+ obeys the Freundlich isotherm. La 3+ adsorbed on resin can be eluted by 2.0 mol/LHCl quantitatively.

Adsorption behavior and mechanism of amino methylene phosphonic acid resin for Ag(I)

The sorption properties of amino methylene phosphonic resin(APAR) for Ag(I) were studied. The amino methylene phosphonic acid resin(APAR) has a good adsorption ability for Ag(I) at pH=6.0 in the HAc-NaAc medium. The statically saturated adsorption capacity is 272 mg/g resin, Ag(I) adsorbed on APAR can be eluted by 5% (NH 2) 2CS-0.5 mol/L hydrochloric acid quantitatively. The adsorption rate constants determined under various temperatures are k 15°C=3.89 × 10 −5S −1, k 25°C=5.93 × 10 −5S −1, k 35°C=7.59 × 10 −5S −1, k 45°C=9.45 × 10 −5S −1, respectively. The apparent activation energy of adsorption, E a is 22.8 kJ/mol, the enthalpy change (Δ H) of sorption is 17.4 kJ/mol. The adsorption mechanism shows that the functional group of APAR coordinates with Ag(I) to form coordination bond, the coordination molar ratio of the functional group of APAR to Ag(I) is 1:1.

Kinetics of adsorption of Zn(II) ion on chitosan derivatives

The adsorption of Zn(II) ions from aqueous solution by chitosan derivatives (KCTS and HKCTS) was studied in a batch adsorption system. The adsorption capacities and rates of Zn(II) ions onto chitosan derivatives were evaluated. The adsorption isothermal data could be well interpreted by the Langmuir and Freundlich models. The kinetic experimental data properly correlated with the second-order kinetic model, which indicates that the chemical adsorption is the rate-limiting step. The apparent adsorption activation energy were 25.47 kJ mol − and 5.473 kJ mol −, respectively, and the second-order adsorption constant for KCTS and HKCTS were 0.00311 g (mg min) −1 and 0.005 g (mg min) −1, respectively.

Adsorption of Sulfur Dioxide in Gaseous Phase on the Porous m-Aminophenol Condensation Resinst

Adsorption equilibrium of sulfur dioxide on the m-aminophenol resins with various pore structures was measured gravimetrically at the temperature range of 20∼60°C and equilibrium pressure up to 760 mmHg. Heats of adsorption were estimated as 14 to 15 kcal/mol using Clausius-Clapeyron equation. Apparent activation energy of adsorption of sulfur dioxide was calculated as 1 kcal/mol from Arrhenius plot. Adsorption capacity of the resins for sulfur dioxide was measured dynamically, by circulating sulfur dioxide (1.77% in N2) over the resins at the flow velocity of 76 cm/min at ambient temperature and pressure, and was compared with that of macroreticular and gel type quaternary ammonium anion-exchange resins in the R-OH form. The adsorption capacity of highly porous resins for sulfur dioxide was 29 to 30 ml-STP/g-dry resin. Adsorption reached nearly equilibrium over the porous resin with ten minutes.

Study of metal catalysts by temperature programmed desorption: II. Chemisorption of hydrogen on platinum

The chemisorption of hydrogen on a platinum black catalyst was investigated over a wide range of temperature (−196 to 400 °) by the temperature programmed desorption (TPD) technique. At least four different states of chemisorbed hydrogen on platinum were indicated by the appearance of four TPD peaks, with peak maxima at about −100, −20, 90, and 300 °. These peaks are referred to as α, β, γ, and δ, respectively, α is the weakest chemisorption and is easily removed by pumping at −100 °. β chemisorption occurs rapidly at −76 ° but cannot be removed by pumping at the same temperature, γ and δ are stronger chemisorptions and occur much more slowly at −76 °. The apparent activation energies of adsorption are about 2.8, 0.9, 0.4, and 2.1 kcal/mole, respectively, for α, β, γ, and δ. Although γ adsorption is slower than α and β at −76 °, it is the only adsorption which occurs appreciably in 10 to 15 min at −196 °, because of its smallest apparent activation energy of adsorption. When all the four types of chemisorption are established at higher temperatures and then brought to −196 °, none of the four chemisorbed forms can be removed by pumping at −196 °. Experimental results indicate that at least β, γ, and δ forms of hydrogen are interrelated to the extent that any one of these more or less retards the chemisorption of the others. It is likely, therefore, that these chemisorptions take place on the same surface but in different forms. The four chemisorptions are tentatively assigned to four different adsorption forms, two atomic and two molecular adsorptions.