Bangham Model Research Articles

Kinetic and Mechanistic Analysis of Phenol Adsorption on Activated Carbons from Kenaf

Activated carbons were prepared from kenaf (Hibiscus cannabinus L.). Carbonization was carried out at 600 °C for 2 h, and activation was performed using air at 600 °C and using CO2 at 750 °C. The activated carbons obtained were treated with HNO3 and H2SO4. The samples were characterized by their chemical and physical structure. The activated carbons obtained were mainly macroporous, and their structure underwent major changes with the activation method and acid treatment. Activated carbons were alkaline and acid-treated carbons were neutral. They were used for phenol adsorption and a kinetic and mechanistic study of adsorption was carried out. The fit to the pseudo-second order and Elovich models was predominant. The rate-limiting step of the process was determined to be diffusion within the pores, as the experimental data fit the Bangham model. DFT simulation showed that the preferred adsorption position involves π-π stacking and that oxidation enhances this interaction. Furthermore, the simulation showed that the interaction of phenol with oxygenated functional groups depends on the type of functional group.

Effect of multi-component gas on removal of trace hydrogen sulfide activity from blast furnace gas using activated carbon adsorbent

Abstract In the steel industry, blast furnace gas (BFG) is huge with complex components. The existence of hydrogen sulfide (H2S) in the BFG can produce sulfur dioxide (SO2) after combustion, which will increase the source of SO2 pollution and make the desulphurization more difficult, to be threat to people health. At present, the removal of H2S by dry adsorption with modified activated carbon adsorbent is a high-precision and low-cost desulphurization method. However, the effect of complex gas components in BFG on the adsorption of H2S by activated carbon adsorbent is not sufficient. Based on the fixed bed adsorbent evaluation system, a new type of highly efficient copper-cerium oxide (Cu–Ce–O) modified activated carbon H2S adsorbent was developed. And the effects of carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2), oxygen (O2), sulfur dioxide and hydrogen chloride (HCl) in BFG on the desulfurization activity of adsorbents were investigated. The results showed that the performance of H2S removal decreased in the presence of CO, CO2, HCl and SO2, and improved in the presence of H2 and O2. Other parameters were also studied which might influence the process. The application of modified activated carbon adsorbent in simulated BFG is basically stable. According to the fitting results of adsorption kinetics for the five adsorption models, as the atmosphere becomes BFG from N2, pore diffusion becomes the main adsorption form. However, the effects of internal diffusion, chemical adsorption and external mass transfer decreased. The Bangham model is the most suitable model to describe H2S adsorption process.

SO3 removal by submicron absorbents synthesized via inhibition method: The product layer grows like parallel peaks

Injecting calcium hydroxide powder into the flue gas is an effective strategy for SO3 removal. However, commercial calcium hydroxide has several disadvantages, including large particle size, low efficiency, and unsuitability for excessive grinding. In this work, sub-micron calcium hydroxide was synthesized by an inhibition method and its performance for SO3 removal from flue gas was investigated on a pilot-scale platform (120 Nm3/h). When the concentration of sodium alginate solution was 100 mg/L, the average particle size of calcium hydroxide decreased from 13.66 µm to 0.84 µm, which improved the SO3 removal (92.1 %) and conversion of the absorbent. The results of the fixed-bed experiments indicate that the absorption kinetics of the reaction is consistent with the Bangham model. In addition, density functional theory verifies that calcium hydroxide captures SO3 by chemisorption. The AFM image shows that the calcium sulfate whiskers produced during the reaction grow like parallel peaks on the adsorbent surface. The calculations suggest that the driving force for SO3 adsorption originates from Ca-p orbital (Ca(OH)2) and O-s orbital (SO3) hybridization. This study complements the island growth mechanism for gas-solid two-phase reactions and provides an effective method for removing SO3 from flue gas in coal-fired power plants. In addition, it will provide an important reference for the development of submicron adsorbents.

Facilely tuning the morphologies of tertiary amine-functionalized SBA-15 for optimizing selective SO2 capture

The amine-based materials pose high potential for the adsorption of sulfur dioxide (SO2). This work is aimed at modulating the morphologies of SBA-15 adsorbents by controlling the precursor self-assembly processes, for the sake of optimizing the utilization efficiency of amine species in the polytertiary amine (PTA)-functionalized SBA-15. It results that worm-like SBA-15 (WLS) material shows a better particle aspect ratio and well-defined pore structure, which helps to optimize the adsorption sites invoked by the preferable dispersion and exposure of PTA, thus amplifying the chemisorption of SO2 on the adsorbent. Consequently, the functionalized WLS-PTA adsorbent exhibits remarkable SO2 adsorption performance (15.43 mmol/g), exceptionally high selectivities of SO2/N2 (27522) and SO2/CO2 (652). Surprisingly, the desulfurization capacity can be further enhanced by the positive effect of the water vapor co-fed. It is unveiled that the whole SO2 adsorption process mainly follows the dual site Langmuir-Freundlich isotherm model and Bangham model. This work sheds light on the design of polymer-solid composite adsorbents for selective capture of SO2.

Adsorption kinetics of CH4 and CO2 on shale: Implication for CO2 sequestration

The adsorption kinetic behavior of CH4 and CO2 in shale is critical for design and practice the CO2 sequestration with enhanced shale gas recovery. In this study, adsorption isotherms and kinetics curves of CH4 and CO2 in two shale samples were measured by the volumetric method at the temperature of 308.15 K, 323.15 K, 338.15 K and 353.15 K with the pressures up to 12 MPa. The pseudo-first-order (PFO) model, pseudo-second-order (PSO) model and Bangham model were used to describe the adsorption kinetics data. Furthermore, the influence of pressure and temperature on the adsorption kinetic behavior of CH4 and CO2 was clarified. The results show that the adsorption kinetic curves can be classified into three stages: rapid adsorption, slow adsorption and adsorption equilibrium stage. The fitting accuracy of the three kinetic models is in the order of Bangham > PSO > PFO. Moreover, the adsorption kinetics of CH4 and CO2 are highly dependent on pressure and temperature. The adsorption rate constant (kb) of CH4 and CO2 increases first and then decreases with increasing pressure. At the pressure below the supercritical pressure of CO2, the kb of CO2 shows a decreasing trend with the increase of temperature, which is the same as that of CH4. However, after exceeding the supercritical pressure of CO2, the variations in kb of CO2 with temperature presents an opposite trend as it increased with increasing temperature. Therefore, the pressure and temperature dependent adsorption kinetic behaviors requires consideration for optimizing engineering parameters in application of CO2 enhanced shale gas recovery and sequestration.

Effects of mesopore size on ethyl acetate adsorption–desorption behaviors over hierarchical ZSM-5/MCM-41 molecular sieves

A series of micro-mesoporous structure ZSM-5/MCM-41 composites with different mesopore sizes were successfully fabricated through surfactant-mediated recrystallization method using the template agents with different alkyl chain length. Mesopore pore sizes were tuned from 2.11 nm to 5.09 nm. Taking ethyl acetate as the VOC probe molecule, the adsorption and desorption properties were evaluated by the dynamic adsorption breakthrough curves and TPD experiments. Results showed that the adsorption capacity was enhanced under dry and humid condition owing to the introduction of mesopore size structure. Especially for ZSM-5/MCM-41 (C12), its adsorption capacity reached up to 208.92 mg·g−1 and 82.29 mg·g−1 at dry and saturated humidity (4 v/v% H2O). Simultaneously, the hierarchical molecular sieves exhibited an excellent regeneration performance. Even after the fifth cycle, above 86% adsorption capacity remained under humid condition. Moreover, the adsorption kinetics of ethyl acetate on ZSM-5/MCM-41 composites followed the Bangham model. The results indicated that hierarchical composite molecular sieve can be considered as a potential adsorbent for VOCs removal.

Synthesis of a high-iron fly-ash-based Na-X molecular sieve and its application in the adsorption of low concentration of CO2.

In addressing the environmental challenges posed by the accumulation of fly ash (FA), efforts have been geared towards its high-value utilization. By the use of high-iron FA as a raw material, a high-iron fly-ash-based Na-X molecular sieve was successfully synthesized by hydrothermal method. We combined pretreatment methods such as high-temperature calcination, acid leaching and alkali fusion activation. The as-synthesized product was used for the adsorption of a low concentration of CO2, and the adsorption data were fitted by a physical model. The changes in iron content in pretreatment and molecular sieve synthesis were revealed by SEM-mapping, UV-Raman and UV-Vis. The results showed that the pretreatment process reduces the iron content from 32.3% to 13.3%, and converts the inactive phases to active phases, with n (SiO2/Al2O3) = 4.94. The activated product was transformed further to a Na-X molecular sieve using a hydrothermal method. The product has a single crystal phase and octahedral crystal structure. Its specific surface area was 646.634 m2 g-1, and micropores were distributed between 0.46 nm and 0.71 nm, with a mesoporous phase of 4.6 nm. When used to adsorb a low concentration of CO2, the Na-X molecular sieve has a high adsorption capacity of 3.70 mmol g-1, which reaches 95.11% that of the commercial Na-X molecular sieve. The adsorption breakthrough time and adsorption capacity decreased with an increase in temperature. The adsorption kinetics were consistent with the Bangham model for surface pore adsorption and Weber-Morris model for internal diffusion. During the synthesis process, iron was converted from highly dispersed iron oxide to four-coordinated framework iron. Thus, this paper paves a path for the high-quality transformation and utilization of high-iron fly-ash.

Use of the Box–Behnken Experimental Design for the Optimization of Orange II (Acid Orange 7) Adsorption on Aloe vera

Industrial wastewater effluents containing dyes are considered to pollute and be harmful to the environment. Among the various removal techniques, the adsorption process using low-cost adsorbents has been successfully used to remove pollutants. In this work, Aloe vera leaves (AVs) have been used as adsorbent for the removal of Orange II (O-II). A three-level three-factor Box–Behnken factorial design, including three replicates of center points, was applied to investigate the main parameters affecting the biosorption of O-II dye in aqueous solutions by AVs. The selected parameters were adsorbent dose, initial dye concentration, and contact time. The Box–Behnken experiment design has given a satisfactory result for the optimization of the adsorption process. The obtained value of R2 (0.9993) shows that the quadratic response model adequately represents the relationship between each response and the chosen variables. The pH influences the adsorption capacity, obtaining at pH 2 the maximum adsorption capacity value. From the kinetic models studied, the one that best describes the adsorption of Orange II on Aloe vera is the Bangham model (ARE = 1.06%). The isotherm model that best represents the experimental data is the Toth model. The maximum adsorption capacity obtained by this model was 15.9 mg·g−1.

Isotherm and kinetic studies for sorption of Cr(VI) onto Prosopis cineraria leaf powder: A comparison of linear and non‐linear regression analysis

AbstractThis research investigated the utilization of Prosopis cineraria leaf powder (PCLP) as biosorbent in the removal of Cr(VI) from aqueous solution. The maximum monolayer biosorption capacity of Cr(VI) onto PCLP after 2 h was 10.283 mg g−1 under optimum conditions: initial concentration 10 mg L−1, pH 5, dose 0.4 g L−1 and temperature at 293 K. For equilibrium modeling, two‐parameters (Langmuir, Freundlich, Temkin) and three parameters (Redlich‐Peterson, Sips and Toth) isotherm models were used to fit the equilibrium data. Kinetic modeling was performed using Lagergren pseudo‐first‐order, pseudo‐second‐order, Elovich, Weber‐Morris intraparticle diffusion, and Bangham's model. Both linear and nonlinear regression were compared coupled with several error functions to determine the best fit and model parameters were evaluated. The results revealed that nonlinear method best explain the experimental data revealing Temkin (R2 = 0.9938) and pseuso‐second‐order (R2 = 0.9935) models as the best‐fitted models with lower error functions. Therefore, the present investigation convinced that PCLP could be used as cost effective, efficient and eco‐friendly biosorbent to reduce Cr(VI) concentration in aqueous solution.

Removal of HCl from gases using modified calcined Mg-Al-CO3 hydrotalcite: Performance, mechanism, and adsorption kinetics

To achieve carbon neutrality, it is essential to remove HCl resulting from the extensive use of alternative fuel feedstock in thermochemical plants. In this work, the HCl removal performance of modified calcined Mg-Al hydrotalcite (Mg-Al-CO3) on gaseous stream was investigated. The layered structure of Mg-Al-CO3 intercalated with CO32– was successfully prepared using the coprecipitation method with a molar ratio of Mg/Al equal to 3.1. The optimal performance of Mg-Al-CO3 for HCl removal was observed at 300 °C, and the breakthrough chlorine capacity was 102.7 mg g−1. Among calcined Mg-Al samples, only Mg-Al-400 exhibited better HCl removal performance than Mg-Al-CO3. The specific surface area of Mg-Al-400 was 183.73 m2 g−1, which was 2.8 times greater than that of Mg-Al-CO3. The average HCl removal rate was 90.11 % within the first 120 min, which was 1.12 times higher than that of Mg-Al-CO3. Moreover, the breakthrough chlorine capacity of Mg-Al-400 was increased by 16.9 %, reaching 120.1 mg g−1. Two reaction paths were identified for Mg-Al-400, first Mg2+ reacts with Cl− to generate MgCl2, and then Cl− acted as a new interlayer anion of hydrotalcite. According to the results of adsorption kinetics, the pseudo-second-order and the Bangham model were found to fit well with the HCl removal process of Mg-Al-400.

Evaluation lead removal kinetics modelling of adsorption by using composite of Chitosan and Ceramic waste

This study focuses on understanding the Pb adsorption kinetics from greywater using a composite of chitosan and ceramic waste (CCCW), which is suitable for preserving water quality. For ease and general application, a kinetic model with a simple expression and a manageable small set of parameters that nevertheless provides a fair adsorption description in the equilibrium state is still critical. Although some current kinetic models, such as the pseudo-second-order type, meet these conditions, their performance is still questionable, especially when applied to a variety of experimental data. Batch adsorption experiments were carried out with the predetermined value of the operational parameter such as adsorbent dosage, contact time, and shaking speed. Kinetic models such as pseudo-first order, pseudo-second order, intraparticle diffusion kinetic model, Avrami model, and the Bangham model were used in this study to understand the kinetics of removal of lead from greywater. The efficacy results of adsorbent’s dose in lead removal process with increasing adsorption capacity with contact time from 0.0014 to 0.00277 mg/g, the removal efficiency increases from 45.90 to 90.83%. The most significant contribution of this work is an understanding of the optimal kinetics model that can describe the behaviour of lead adsorption on CCCW. Five models for the adsorption of Pb2+ have been identified to clarify the kinetics models’ usefulness in accuracy based on rank order. This study may provide insight into understanding the ability and usability of the appropriate model in kinetics adsorption.

New Porous Carbon Material Derived from Carbon Microspheres Assembled in Hollow Carbon Spheres and Its Application to Toluene Adsorption.

In this paper, a new porous carbon material adsorbent was prepared using carbon microspheres assembled in hollow carbon spheres (HCS) with a hydrothermal method. Transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and Raman spectroscopy were used to characterize the adsorbents. It was found that the diameter of carbon microspheres derived from 0.1 mol/L glucose was about 130 nm, which could be inserted inside HCS (pore size was 370-450 nm). The increase in glucose concentration would promote the diameter of carbon microspheres (CSs), and coarse CSs could not be loaded in the mesopores or macropores of HCS. Thus, the C0.1@HCS adsorbent had the highest Brunauer-Emmett-Teller surface area (1945 m2/g) and total pore volume (1.627 cm3/g). At the same time, C0.1@HCS posed a suitable ratio of micropores and mesopores, which could provide adsorption sites and volatile organic compound diffusion channels. Moreover, oxygen-containing functional groups -OH and C═O in CSs were also introduced into HCS, and the adsorption capacity and regenerability performance of the adsorbents were improved. The dynamic adsorption capacity of C0.1@HCS for toluene reached 813 mg/g, and the Bangham model was more suitable for describing the toluene adsorption process. The adsorption capacity was stably kept above 770 mg/g after eight adsorption-desorption cycles.

Kinetics of Gas Phase CO2 Adsorption on Bituminous Coal from a Shallow Coal Seam

This article examines the CO2 adsorption–desorption kinetics of bituminous coal under low pressure injection (0.5 MPa) in the context of CO2 sequestration in shallow level coal seams. This study used two different sizes of intact core samples of bituminous samples from seam no. 30 at the Experimental Mine Barbara (EMB) in Katowice, Poland. Manometric adsorption kinetics experiments were conducted on 50 mm dia. 60 mm long coal core samples (referred to as EMB1) and 50 mm dia. 30 mm long coal core samples (referred to as EMB2). The kinetics of adsorption at injection pressures ranging from 0.1 to 0.5 MPa were compared to those at elevated pressures ranging from 0.5 to 4.5 MPa. For the first time, intact sample adsorption–desorption data were fitted in pseudo first order (PFO), pseudo second order (PSO), and Bangham pore diffusion models. The PSO model fits the data better than the PFO model, indicating that bulk pore diffusion, surface interaction, and multilayer adsorption are the rate-determining steps. Comparing the equilibrium amount of adsorbed (qe) obtained for the powdered samples (9.06 g of CO2/kg of coal at 0.52 MPa) with intact samples (11.68 g/kg at 0.53 MPa and 7.58 g/kg at 0.52 MPa for the intact EMB1 and EMB2 samples) showed the importance of conducting experiments with intact samples. The better fit obtained with the Bangham model for lower pressure equilibrium pressures (up to 0.5 MPa) compared to higher pressure equilibrium pressures (4.5 MPa) indicates that bulk pore diffusion is the rate-determining step at lower pressures and surface interaction takes over at higher pressures. The amount of CO2 trapped within the coal structure following the desorption experiments strengthens the case for intact bituminous coal samples’ pore trapping capabilities.

Experimental Study of Temperature Effect on Methane Adsorption Dynamic and Isotherm

Knowing the methane adsorption dynamic is of great importance for evaluating shale gas reserves and predicting gas well production. Many experiments have been carried out to explore the influence of many aspects on the adsorption dynamic of methane on shale rock. However, the temperature effect on the adsorption dynamic as a potential enhanced shale gas recovery has not been well addressed in the publications. To explore the temperature effect on the adsorption dynamic of methane on gas shale rock, we conducted experimental measurement by using the volumetric method. We characterized the adsorption dynamic of methane on gas shale powders and found that the curves of pressure response at different pressure steps and temperatures all have the same tendency to decrease fast at first, then slowly in the middle and remain stable at last, indicating the methane molecules are mainly adsorbed in the initial stage. Methane adsorption dynamic and isotherm can be well fitted by the Bangham model and the Freundlich model, respectively. The constant z of the Bangham model first decreases and then increases with equilibrium pressure increasing at each temperature, and it decreases with temperature increasing at the same pressure. The adsorption rate, constant k of the Bangham model, is linearly positively correlated with the natural log of the equilibrium pressure, and it decreases with temperature increasing at the same pressure. Constant K and n of the Freundlich model all decrease with temperature increasing, indicating that low temperatures are favorable for methane adsorption on shale powders, and high temperatures can obviously reduce constant K and n of the Freundlich model. Finally, we calculated isosteric enthalpy and found that isosteric enthalpy is linearly positively correlated with the adsorption amount. These results will be profoundly meaningful for understanding the mechanism of methane adsorption dynamic on shale powders and provide a potential pathway to enhance shale gas recovery.

Combining biological and chemical methods to disassemble of cellulose from corn straw for the preparation of porous carbons with enhanced adsorption performance

In this study, we used a combination of chemical and biological pretreatment methods to extract cellulose from corn straw with a relative content of 92.40%. The adsorption performance and mechanism of the prepared porous carbon were investigated using synthetic dye malachite green (MG) and antibiotic tetracycline hydrochloride (TC) as adsorption models. The kinetic studies suggested that the adsorption followed the pseudo-second-order model and Bangham model. The Freundlich isotherm model fitted the adsorption data best for both MG and TC. The thermodynamic studies showed that the adsorption of MG and TC by adsorbents were spontaneous and endothermic in nature. In addition, the adsorption performance was maintained at 50% of the original value after five cycles. More importantly, this method not only improved the adsorption performance of prepared porous carbon materials but also provides a reference for the application of other lignocellulosic materials for cellulose extraction.

Adsorption mechanism study of multinuclear metal coordination cluster Zn5 for anionic dyes congo red and methyl orange: Experiment and molecular simulation

This study aimed to investigate the adsorption behaviors of congo red (CR) and methyl orange (MO) on the coordination cluster Zn5(H2Ln)6(NO3)4 (Zn5, H3Ln = 1,2-bis-(benzo[d]imidazol-2-yl)-ethenol). Due to multinuclear assembly, multinuclear Zn5 possessed higher electrostatic potential and exhibited 3-fold enhancement in removal efficiency, compared with mononuclear Zn (Zn(H3L)2, H4L = 1,2-bis-(benzo[d]imidazol-2-yl)-1,2-ethanediol). The infrared and X-ray photoelectron spectroscopy and the electrostatic potential analysis indicated that the adsorption mechanism was electrostatic interaction and ion exchange interaction. The adsorption kinetics followed both the pseudo first-order and Bangham models. The pore system analysis and Bangham model suggested that CR and MO could diffuse in the snakelike pores of Zn5. The adsorption isotherms complied with the Langmuir isotherm model, and the maximum adsorption capacities for CR and MO are 166.91 and 100.78 mg/g at room temperature. The adsorption process was spontaneous and endothermic, driven by the entropy increase. Based on this research, the multinuclear coordination clusters can be suggested as potential adsorbents for the removal of anionic dyes.

Hierarchical porous activated carbon from wasteZanthoxylum bungeanum branches by modified H3PO4 activation for toluene removal in air.

Activated carbon adsorbents were prepared by chemical activation with waste Zanthoxylum bungeanum branches as raw materials and H3PO4/H2SO4 as composite activator under different dosages of the auxiliary activator H2SO4. The prepared samples were characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface area test, Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The adsorption/desorption performances of low concentration toluene in the air were evaluated, and its reusability was evaluated by the adsorption/desorption cycle. Adsorption results were fitted using the quasi-first, quasi-second, and Bangham models. The adsorption properties of activated carbon adsorbent for toluene in the air show a "volcanic-type change trend" with the increase of H2SO4 dosage. The toluene adsorption properties of the prepared activated carbon adsorbents from high to low are as follows: BAC02 > BAC05 > BAC01 > BAC10 > BAC00. When the mass fraction of auxiliary activator H2SO4 was 2.0%, the adsorption amount of toluene on the prepared BAC02 activated carbon adsorbent increased by 51%, reaching 511mg/g. After thermal desorption at 200℃, the adsorption performance of toluene was regenerated. The adsorption process of toluene conforms to the quasi-first-order model and Bangham model. The whole adsorption process can be divided into three stages: outer surface adsorption, intra-channel diffusion, and adsorption equilibrium. The addition amount of H2SO4 significantly affected the specific surface area, pore volume, and pore size distribution of the prepared activated carbon adsorbent.

Preparation of Synthetic Clays to Remove Phosphates and Ibuprofen in Water

The main objective of this study consists in the synthesis of a layered double hydroxide (LDH) clay doped with magnesium and aluminum in order to test the removal of phosphates and ibuprofen in water. Two different LDH composites are assessed: oven-dried (LDHD) and calcined (LDHC). Single adsorptions of phosphate and ibuprofen showed up to 70% and 58% removal in water, when LDHC was used. A poorer performance was observed for LDHD, which presented adsorption efficiencies of 52% and 35%, respectively. The simultaneous removal of phosphate and ibuprofen in water showed that LDHC allows a greater reduction in the concentration of both compounds than LDHD. Phosphate adsorption showed a close agreement between the experimental and theoretical capacities predicted by the pseudo-second-order model, whereas ibuprofen fitted to a first-order model. In addition, phosphate adsorption showed a good fit to an intraparticle diffusion model and to Bangham model suggesting that diffusion into pores controls the adsorption process. No other mechanisms may be involved in ibuprofen adsorption, apart from intraparticle diffusion. Finally, phosphate desorption could recover up to 59% of the initial concentration, showing the feasibility of the recuperation of this compound in the LDH.

Adsorption of Hydrogen Sulfide at Low Temperatures Using an Industrial Molecular Sieve: An Experimental and Theoretical Study.

In the work presented herein, a joint experimental and theoretical approach has been carried out to obtain an insight into the desulfurization performance of an industrial molecular sieve (IMS), resembling a zeolitic structure with a morphology of cubic crystallites and a high surface area of 590 m2 g–1, with a view to removing H2S from biogas. The impact of temperature, H2S inlet concentration, gas matrix, and regeneration cycles on the desulfurization performance of the IMS was thoroughly probed. The adsorption equilibrium, sorption kinetics, and thermodynamics were also examined. Experimental results showed that the relationship between H2S uptake and temperature increase was inversely proportional. Higher H2S initial concentrations led to lower breakpoints. The presence of CO2 negatively affected the desulfurization performance. The IMS was fully regenerated after 15 adsorption/desorption cycles. Theoretical studies revealed that the Langmuir isotherm better described the sorption behavior, pore diffusion was the controlling step of the process (Bangham model), and that the activation energy was 42.7 kJ mol–1 (physisorption). Finally, the thermodynamic studies confirmed that physisorption predominated.

Kinetic and Isotherm Modelling of the Adsorption of Congo Red Dye onto NiFe2O4 and NiFe2O4 decorated Exfoliated Graphite

Adsorption using novel materials is a common and highly applicable process in remediation of hazardous dyes in wastewater. Herein, we attempted the synthesis of NiFe2O4 decorated-exfoliated graphite (EG@NiFe2O4), an inexpensive and environmental benign material, and analyzed the adsorption process of the as-synthesized adsorbent against Congo red dye. Kinetic of the adsorption was investigated using various models including first-pseudo kinetic, second-pseudo kinetic, Bangham model and Elovich model. Isotherm of the process was evaluated by Langmuir, Freundlich, Temkin and Dubinin − Radushkevich model. Lastly, thermodynamic parameters of the adsorption towards Congo red dye was calculated. Our findings indicated that kinetic and isotherm of the adsorption process of both adsorbents (EG@NiFe2O4 and NiFe2O4) could be well explained by the pseudo-second-order model (R2 > 0.99) and Langmuir isotherm (R2 =) respectively. In addition, kinetic parameters showed that EG@NiFe2O4 possesses greater adsorption capacity in comparison with NiFe2O4. Estimated thermodynamic parameters also indicated the spontaneous and endothermic adsorption (ΔG=) of the EG@NiFe2O4 composite against Congo red dye.