Thermodynamics Of Methylene Blue Adsorption Research Articles

Kinetics and thermodynamics of methylene blue adsorption onto black plum seed-based graphene oxide

Abstract The kinetics and thermodynamics of methylene blue adsorption from aqueous solution was studied using low-cost biomass graphite (CVDM) and graphene oxide (SGO) derived from black plum seed. The effects of pH in the range of 2.2–12.5, adsorbent dosage in the range of 25–100 mg and solution temperature in the range of 28.7–90 °C were studied. The optimum conditions were recorded at pH 4.8, dosage of 25 mg and solution temperature of 70 °C. The pseudo-second-order model demonstrated the best fit to experimental data (R 2 → 1 and SSE = 3.69), rapid rate constant (K s = 0.0868 g/mg.min) and empirical adsorption capacity of 4.12 mg/g. The adsorption of methylene blue onto SGO increased with solution temperature to 70 °C before it decreased, suggesting a weakening of the attractive adsorbent-adsorbate forces due to collisions among methylene blue molecules.

Improved carboxylate density hydrochar by alkylation of surface phenol for adsorption of cationic dye in aqueous solution

Methylene blue (MB) adsorption in aqueous solution studied using rice straw derived hydrochar (RSH) and carboxylate functionalized hydrochar (RSHC) as adsorbent. RSHC with improved carboxylate functional group density was prepared by selective functionalization of phenolic oxygen functional groups present on RSH surface. The RSH and RSHC were characterized by ultimate and proximate analysis, Boehm Titration, 13C CP-MAS SS NMR, XPS, SEM, BET surface area and zeta potential analysis. Batch adsorption experiments were optimized for MB adsorption were, adsorbent dose of 0.2 g/L, pH 8 and 7, respectively for RSH and RSHC, with 3.5 h contact time at 298 K. Nonlinear fit to Langmuir, Freundlich, Temkin, d-R models and Sips isotherm models, showed good fit with R2>0.95. RSHC (Qm = 434.6 mg/g) showed four-fold increase in MB adsorption as compared to the pristine hydrochar RSH (Qm =111.6 mg/g). Contact time study showed good nonlinear fit to pseudosecond order model indicating a strong interaction between hydrochar adsorbents and MB. Thermodynamics of MB adsorption (288–308 K) onto the surface of RSH and RSHC, is a spontaneous process with ∆G° -23.85 and -28.31 kJ/mol, respectively. RSH in characterized by enthalpy driven adsorption characteristic of proton-MB exchange, whereas in case of RSHC, K+–MB exchange is entropically driven process.

Efficient removal of methylene blue dye from wastewater specimen using polystyrene coated nanoparticles of silica

Utilization of suitable methodologies for recovery of wastewater and its reuse in various applications is highly stimulated. In agreement with this objective, the current research study presents new adsorbents, composed of silica nanoparticles coated by a polystyrene shell, for use in the purification of wastewater from methylene blue (MB) dye, as a contaminant. Firstly, silica nanoparticles were prepared and covered by a layer of Polystyrene made via the high internal phase emulation (HIPE) polymerization technique. Three composite structures having different contents of silica nanoparticles (by weight %) were designated as adsorbents in this research work. The chemical and structural properties of these adsorbents were verified by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy while their textural characteristics were acquired by scanning electron microscopy (SEM) and N2 adsorption-desorption surface area analysis. The efficiencies of these adsorbents toward disposal of MB dye from wastewater were next investigated at different operating parameters. The introduced composites of polystyrene@silica nanoparticles revealed promising capacities toward adsorption of MB dye which came up to a maximum of 23.1 mg g−1. The observed removals of MB dye by these composites during the process of water purification are attributed to the presence of both organic and inorganic functional groups within their structures. Thus, various adsorption mechanisms could take place through the elimination of MB particles from the effluent water during the treatment process. Kinetic and isotherm studies for the adsorption of MB species were found to fit the models of pseudo-second-order and Langmuir respectively. Furthermore, the thermodynamics of MB adsorption could indicate the nature of such process as feasible, spontaneous, physisorption, and exothermic.

Characterization and Analysis of Argania spinosa Shells from Souss‐Massa Area: Application in the Adsorption of Methylene Blue in Aqueous Solution

This study focused on the adsorption in aqueous solution of methylene blue (MB), a cationic dye used in the textile industry, by crushed Argan shells (used as raw materials) from the southern region of Morocco. These crushed Argan shells were first characterized by different technical analyses: elemental analysis, biochemical analysis, IR spectroscopy, thermogravimetric analysis, scanning electron microscopy, mercury porosimetry, and zetametry. The adsorption kinetics was then studied by varying the experimental parameters such as the dye concentration in solution. We note that at pH = 8, there is an elimination up to 232.6 mg/g, during an equilibrium time of 180 min. The correlation coefficient showed that the pseudosecond‐order kinetic equation best describes the adsorption kinetics for the tested material. The adsorption isotherms of MB by Argan shells are suitably described by the Langmuir model which provide the best theoretical correlation of the experimental data. The thermodynamics of MB adsorption on Argan shells indicates a spontaneous and endothermic process. It was concluded that an increase in temperature leads to a greater adsorption of MB by the studied biosorbent.

Thermodynamics and kinetics of the removal of methylene blue from aqueous solution by raw kaolin

Remediation of contaminated water with organic dyes originated from variety of industrial processes deserves increased attention. Raw clay is an effective low-cost and eco-environmentally friendly adsorbent for the removal of methylene blue (MB) from solution. This study aims to determine kinetics and thermodynamics of MB adsorption onto raw kaolin clays (halloysite and kaolinite/illite) from northeast of Morocco. The apportion capacity of the two kaolin clays to adsorb the MB dye by varying temperature and pH conditions was studied. The thermodynamic parameters show that the sorption of MB is spontaneous and endothermic for halloysite-rich clay, whereas adsorption onto kaolinite/illite is inhibited by electrostatic exothermic effects and the sorption is thermodynamically unfavorable. The kinetic study showed that the adsorption capacity of MB on halloysite is greater than on kaolinite. The intraparticle diffusion process controls the adsorption reaction, and the kinetic is more important for halloysite.

Kinetics and thermodynamics of methylene blue adsorption on the Fe-oxide nanoparticles embedded in the mesoporous SiO2

Fe-oxide nanoparticles with a diameter of ~10 nm embedded into the porous structure of mesoporous SiO2 particles using temperature regulated chemical vapor deposition and a subsequent annealing process. The kinetics and thermodynamics of MB adsorption on bare SiO2 and Fe-oxide/SiO2 particles were investigated. MB adsorption kinetics of both SiO2 particles can be described by pseudo first order and intra particle diffusion plot. Thermodynamic parameters were calculated based on the modified Langmuir isotherm model. Equilibrium constant and spontaneity of MB adsorption was increased with the presence of Fe-oxide nanoparticles inside the SiO2 pores, which can be ascribed to the more negative values of ΔH of Fe-oxide/SiO2 particles compared to bare SiO2. A higher affinity of Fe-oxide nanoparticles for MB adsorption facilitated the intra particle diffusion of MB molecules at a longer time of MB adsorption and improve the maximum MB adsorption capacities of Fe-oxide/SiO2 compared to bare SiO2. The maximum MB adsorption capacities of bare SiO2 and Fe-oxide/SiO2 particles reduced as the initial pH of MB solution increased, however, Fe-oxide/SiO2 particles always exhibited the higher capacity of MB adsorption than bare SiO2.

A study of kinetics and thermodynamics of methylene blue adsorption onto the Yellow River bottom sediment

AbstractIn this paper, the adsorption process and kinetics of methylene blue onto the Yellow River bottom sediment was investigated. It was found that the equilibrium data fitted well to the Langmuir, Freundlich, Toth and Redlich‐Peterson model, with the Langmuir model showing the best fitting result compared to others. The adsorption process attained equilibrium within 60 min, and the adsorption capacity of Yellow River sediment increased with the increase in adsorbent concentration, temperature, and NaNO3 concentration. The adsorption capacity of the Yellow River sediment increases as the adsorbent pH decreases to a certain value and further decreasing the pH value can lead to decreasing adsorption capacity. Moreover, the presence of humic acid in natural concentration range had a minor influence on the adsorption quantity of the Yellow River sediment. Therefore, the Yellow River sediment, an easily available material, can be used for methylene blue removal in wastewater treatment processes.

Kinetic and Thermodynamics of Methylene Blue Adsorption onto Zero Valent Iron Supported on Mesoporous Silica

Zero valent iron supported on mesoporous silicanano particles (NZVI/MSNs) was prepared by the aqueous phase borohydride reduction methods. Prior to the reduction, mesoporous silica nanoparticles (MSNs) were prepared through the activation of fumed silica with concentrated HCl by refluxing at 90 °C. FTIR, XRD, FESEM, EDX and BET were used to characterize theadsorbents prepared. BET surface areas of MSNs, NZVI, and NZVI/MSNs were 126, 41, and 72 m2/g for, respectively. The performance of NZVI/MSNs as adsorbent was examined by adsorption of methylene blue (MB), performed in series of batch experiments. In the kinetic studies, pseudo first order and pseudo second order kinetic models were examined. The pseudo second order equation provided the best fit with the experimental data. Thermodynamic studies indicated that the adsorption process is endothermic with ΔH° was 90.53 kJ/mol. Positive ΔS° (300 J/mol) and negative ΔG° (-6.42 kJ/mol) was recorded, indicating the spontaneous of the adsorption process and naturally favorable.

Kinetics, equilibrium studies and thermodynamics of methylene blue adsorption on Ephedra strobilacea saw dust and modified using phosphoric acid and zinc chloride

In this research, three adsorbents, namely, Ephedra strobilacea char (ESC), E. strobilacea char modified using phosphoric acid (ESP) and E. strobilacea char zinc chloride (ESZ) were prepared for the adsorption of methylene blue. Adsorption was studied as a function of pH (2–11), adsorbent dose (0.01–0.1g), time (1–120min), initial MB concentration (30–100mg/L), agitation speed (120–180rpm) and temperature (298–338K). From the results obtained it was observed that with the increase in the pH value, the percentage MB removal increases from 48.62, 68.74 and 46.68% to 92.69, 99.71 and 95.33% for ESC, ESP and ESZ adsorbents, respectively. Hence the optimized pH value for ESC, ESP and ESZ is 8, 6 and 9 respectively. Additionally the percentage MB removal increased from 55.2, 56.19 and 58.25% to 95.81, 99.5 and 95.5% for ESC, ESP and ESZ adsorbents, respectively, by increasing adsorbent dose from 0.01 to 0.1g. Hence the optimized adsorbent dose for ESC, ESP and ESZ is 0.05, 0.07 and 0.05g respectively. The experimental data were analyzed by the Langmuir, Freundlich, and Temkin isotherms. Results showed that the maximum monolayer adsorption capacity of ESC, ESP and ESZ adsorbents for the adsorption of MB was 31.152, 21.929 and 37.037mg/g at 318K, respectively. The kinetic data were fitted to the pseudo-first-order, pseudo-second-order and intraparticle diffusion models. Adsorption of these adsorbents followed Langmuir adsorption isotherm models and pseudo-second-order kinetics. Thermodynamic parameters were evaluated to predict the nature of adsorption. These results indicate the endothermic and spontaneous nature of the adsorption process.

Interaction and thermodynamics of methylene blue adsorption on oxidized multi-walled carbon nanotubes

AbstractMulti-walled carbon nanotubes (MWCNTs) and their oxidized derivatives were used as adsorbents for the removal of methylene blue dye from aqueous solution. CNTs have consistent surface and distinct structure, thus they were selected as the novel adsorbents in this study. The site-energy distribution analysis could provide significant information for adsorption mechanisms. Therefore, this study concentrated on the site-sorption energy distribution analysis in combination with thermodynamic behavior of methylene blue adsorption on CNTs. The single point adsorption coefficient

Equilibrium, Kinetics, and Thermodynamics of Methylene Blue Adsorption by Pine Tree Leaves

The adsorption capacity of pine tree leaves for removal of methylene blue (MB) from aqueous solution was investigated in a batch system. The effects of the process variables, such as solution pH, contact time, initial dye concentration, amount of adsorbent, agitation speed, salt concentration, and system temperature on the adsorption process were studied. The extent of methylene blue dye adsorption increased with increase in initial dye concentration, contact time, agitation speed, temperature, and solution pH but decreased with increased in amount of adsorbent and salt concentration. Equilibrium data were best described by both Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity of pine tree leaves biomass was 126.58 mg/g at 30 °C. The value of separation factor, R L , from Langmuir equation and Freundlich constant, n, both give an indication of favorable adsorption. The intrapartical diffusion model, liquid film diffusion model, double exponential model, pseudo-first and second order model were used to describe the kinetic and mechanism of adsorption process. A single stage bath adsorber design for the MB adsorption onto pine tree leaves has been presented based on the Langmuir isotherm model equation. Thermodynamic parameters such as standard Gibbs free energy (ΔG 0), standard enthalpy (ΔH 0), and standard entropy (ΔS 0) were calculated.

Kinetics and thermodynamics of methylene blue adsorption by cobalt-hectorite composite

The cobalt-hectorite composite is used for the removal of MB from aqueous solution. Research concerning the effects of pH, composite dose, initial dye concentration and temperature are presented and discussed. Experiment data was analyzed using pseudo-second-order kinetics, intra-particle diffusion, and film diffusion. The characteristic parameters for each model have been determined. Thermodynamic parameters such as activation ( E a), standard free energy (Δ G o), the enthalpy (Δ H o) and the entropy (Δ S o) were also evaluated. The negative value of Δ G o (kJ/mol) and Δ H o (kJ/mol) indicates the spontaneous and exothermic nature of the reactions. The data of E a shows the physisorption process of MB adsorption on Co-hectorite composite.

Kinetics and thermodynamics of Methylene Blue adsorption on Neem ( Azadirachta indica) leaf powder

The dye, Methylene Blue, was adsorbed on an adsorbent prepared from mature leaves of the Neem tree ( Azadirachta indica). A batch adsorption study was carried out with variable adsorbate concentration, adsorbent amount, pH, and temperature. Ninety-three percent of the dye could be removed by 2 g of the Neem leaf powder from 1 L of an aqueous solution containing 25 mg of the dye at 300 K. The adsorption followed pseudo first order kinetics with a mean rate constant of 3.73 × 10 −3 min −1 and an intra-particle diffusion rate constant of 6.36 × 10 −2 mg g −1 min −0.5. A possible mechanism of adsorption was suggested on the basis of concurrently operating surface adsorption and pore diffusion. The experimental data yielded excellent fits with Langmuir and Freundlich isotherm equations. The Langmuir monolayer capacity had a mean value of 8.76 mg g −1. The adsorption of the dye was endothermic in nature (Δ H: 4.62–16.74 kJ mol −1) and was accompanied by an increase in entropy (Δ S: 54.22–90.23 J mol −1 K −1) and a decrease in Gibbs energy (Δ G: −10.33 to −13.62 kJ mol −1 in the temperature range of 300–330 K). The results indicated that the dye, Methylene Blue, strongly interacts with a biomass-based adsorbent, the Neem leaf powder.