Methylene Blue Adsorption Process Research Articles

A novel TMD/MOF (Transition Metal Dichalcogenide/Metalorganic frameworks) composite for highly and selective adsorption of methylene blue dye from aqueous mixture of MB and MO

The removal of organic dye effluents released from numerous dye-utilizing industries is of increasing concern. In this study, the efficiency of wastewater dye adsorption methods was studied by synthesizing and characterizing MoS2-COOH @ UiO-66-NH2 composite based on a novel type of transition metal dichalcogenide/metal-organic frameworks (TMD/MOF) prepared using basic materials such as MoS2, and UiO-66-NH2. The fabricated MoS2-COOH @ UiO-66-NH2 composite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal stability (TGA), FT-IR spectroscopy, and Energy Dispersive X-ray mapping analysis. In addition, the surface charge of the nanocomposite was probed with Zeta potential (ζ) measurements using the Dynamic Light Scattering (DLS) technique. TMD/MOF composites, as adsorbents, were investigated under various experimental conditions and their equilibrium adsorption capacity towards MB was found to be up to 253mgg−1 (when pH = 7.0, contact time was 100 min, the adsorbent dose was 6 mg and initial MB concentration was 75 mgL − 1 (30 ml) Using the pseudo-first-order and pseudo-second-order models to study the kinetic behavior of the adsorption process, a better performance of the pseudo-second-order model in describing the kinetic behavior of the MB and MO adsorption process was observed. In addition, MoS2-COOH @ UiO-66-NH2 composites could selectively separate methylene blue from a mixture of MB (methylene blue) and MO (methyl orange) with a separation efficiency of 86%.

Quaternary Ammonium Functionalized Lignosulfonate for Simultaneous Adsorption of Anionic/Cationic Dyes and Desinfection

AbstractAlthough various adsorbents have been developed for sewage treatment, only a few adsorbents can simultaneously adsorb anions/cations and disinfect. In this work, a quaternary lignosulfonate (Q‐LSP) was prepared, which can not only simultaneously adsorb anion and cation pollution, but also disinfect. FT‐IR, XPS were employed to confirm successful preparation of Q‐LSP. The Q‐LSP adsorbs cationic dye methylene blue (MB) and anionic dye Congo red (CR) favorably, and the maximum qe of Q‐LSP to MB and CR are 153 and 324 mg/g respectively according to Langmuir isotherm model. The Langmuir isotherm and pseudo‐second‐order kinetic models are more suitable to describe the adsorption process of MB and CR on Q‐LSP. In binary system containing MB and CR, Q‐LSP can simultaneously adsorb MB and CR, with MB adsorbed preferentially. The Q‐LSP loaded MB or CR is easily regenerated, and the adsorption properties of regenerated Q‐LSP only decreases by 9.2 % to CR and 9.6 % to MB respectively after 4 desorption‐resorption cycles. Moreover, the Q‐LSP can disinfect by leaking endogenous chemicals. Therefore, the Q‐LSP can be used as a new adsorbent possessing performance of simultaneously adsorbing anionic/cationic pollutants and bactericidal activities.

Improving the removal efficiency of methylene blue on 3D-printed camellia seed powder scaffold using porogen

This paper proposes a strategy for improving the adsorption efficiency of methylene blue (MB) on 3D-printed camellia seed powder (CSP) scaffold. Polyvinyl alcohol (PVA) was employed as a porogen for CSP blended with polylactic acid (PLA) and poly(butylene succinate) (PBS). The PLA/PBS/CSP/PVA composite scaffold was fabricated via 3D-printing technique. And the prepared scaffold was eroded by water for enhancing the porosity. The scaffold with and without water-erosion were characterized respectively, and their MB adsorption performances and mechanism were investigated. The porosity of PLA/PBS/CSP/PVA with water-erosion and PLA/PBS/CSP scaffolds are 48.37 % and 21.24 % respectively, and the corresponding removal efficiency of MB in 100 mg/L MB solution for 12 h are 89.84 % and 57.27 %, suggesting that the construction of porous obviously accelerates adsorption speed of MB on the scaffold. The MB adsorption process of the scaffold with water-erosion can be described by Pseudo-second-order model. The adsorption isotherms indicate that a monolayer adsorption is formed on the scaffold surface. The statistical physics monolayers models and experimental characterization were further employed to investigate the adsorption mechanism of MB molecules on scaffold. Moreover, the adsorption ratio of the scaffold with water-erosion remains 98.21 % at 7 runs of adsorption-desorption experiment, exhibiting a good reusability. These results will open a new understanding in the design and preparation of a new candidate for dye molecules removal with high efficiency.

Adsorption mechanism of methylene blue from water using core-shell structured magnetic Mn0.6Zn0.4Fe2O4@SiO2 as efficient recyclable adsorbent

To improve the performances of solid-liquid separation and in situ regeneration of adsorbents for the removal of azo dye methylene blue (MB) in water, core-shell structured Mn0.6Zn0.4Fe2O4@SiO2 (MZFS) magnetic nanocomposite (MNC) adsorbents were prepared and characterized. Adsorption kinetics, isotherms and thermodynamics were investigated. Then, the in situ regeneration of MB-binding MZFS-MNCs by advanced oxidation processes (AOPs) was conducted, and the reusability of MZFS-MNCs was evaluated. The adsorption mechanism was revealed based on the results of Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy. The results indicated that Mn0.6Zn0.4Fe2O4 magnetic nanoparticles were encapsulated within silica shells. The MZFS-MNC surface was rough and porous, and the specific surface area was 242 m2 g−1. The saturation magnetization of MZFS-MNCs was 18.6 emu·g−1. The kinetics and isotherms of the MB adsorption process can be described by the pseudo-second-order kinetic model and the Langmuir model, respectively. The results of adsorption thermodynamics indicated that MB adsorption on MZFS-MNCs was spontaneous and endothermic, and physisorption was the dominant process. The adsorption process was driven by the electrostatic interaction, electron-donor–acceptor interaction, and intermolecular hydrogen bonding. Only one dimethylamino group in the MB molecule participated in the MB adsorption. The hydroxyl oxygen MZFS-MNCs were involved in MB adsorption, while the lattice oxygen did not participate in adsorbing MB. The oxygen vacancies were favorable for the adsorption of MB and in situ regeneration of MB-binding MZFS-MNCs by AOPs.

NaY zeolite and TiO2 impregnated NaY zeolite for the adsorption and photocatalytic degradation of Methylene blue under Sunlight

NaY zeolite was impregnated by TiO2 to prepare novel catalyst for the adsorption and photocatalytic degradation of methylene blue (MB). The samples were characterized by XRD, SEM, EDS and FTIR techniques. The percentage adsorption of MB on NaY reaches 88% and adsorption capacity of 6.55 mg/g under optimized parameters ([MB] = 10 mg/L, pH = 6, S/L = 2 mg/L and T = 25°C). The MB adsorption process follows Langmuir isotherm. The thermodynamic parameters were investigated and showed an endothermic and physical process. The MB adsorption also follows a pseudo second-order kinetic. The photo-degradation of the MB dye was successfully carried out on the TiO2/NaY catalyst under sunlight. The MB photo-degradation also follows a Langmuir-Hinshelwood first-order kinetic.

Evaluation of surface phenomena of magnetic biomass for dye removal via surface modeling

Methylene blue (MB) dye is used in various industries; however, it is detrimental to both humans and the environment. This study reports on the adsorptive removal of methylene blue (MB) using a magnetically modified agro-waste: iron oxide loaded Lonicera japonica flower powder (IOLJF). The interaction effects of operating variables such as the initial MB concentration, temperature, dosage of IOLJF, and pH on the IOLJF removal efficiency for MB were investigated systematically and statistically. The results showed that the adsorptive removal of MB was explained well by the pseudo-second-order (PSO) kinetic model and the Langmuir and Freundlich isotherms. The maximum uptake capacity was 403.44 mg/g at pH 6.0 and 293 K. The MB adsorption process was complex on the surface of the IOLJF. To comprehend the essential characteristics and envision the removal efficiency in the batch adsorption process, two approaches were used, namely the response surface methodology (RSM) and the data-driven adaptive neuro-fuzzy inference system (ANFIS). The RSM (R2 = 0.9782) and ANFIS (R2 = 0.9964) model predictions were both good and comparable with the experimental data. Further, it was found that the magnetic biomass could be re-used for up to seven cycles without losing its efficacy of ~95%. Overall, the results indicated that the IOLJF had sufficient potential for wastewater treatment.

The Use of Sugarcane Bagasse to Remove the Organic Dyes from Wastewater.

In the present study, the potential of sugarcane bagasse (SCB) was evaluated by methylene blue (MB) retention. The selected low-cost adsorbent was characterized by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), BET method, and determination of the point of zero charge (pHzpc). Batch kinetic and isothermal studies were performed to examine the effects of contact time, initial dye concentration, adsorbent dose, pH, and temperature. The results show that the kinetic study of MB adsorption on sugarcane bagasse is very fast; the equilibrium is reached after only 20 minutes. The kinetic model of pseudo-second-order and the Langmuir isotherm model perfectly explain the adsorption process of MB with a monolayer adsorption capacity equal to 49.261 mg·g−1 activation parameters' values such as free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°) also determined as −4.35 kJ·mol−1, −31.062 kJ·mol−1, and −0.084 J·mol−1·K−1, respectively. Besides, the thermodynamic parameters of the methylene blue sugarcane bagasse system indicate that the exothermic adsorption process is spontaneous.

Organic Dyes Adsorption on the Almond Shell (Prunus dulcis) as Agricultural Solid Waste from Aqueous Solution in Single and Binary Mixture Systems

Almond shell (AS) is a low-cost adsorbent used in this study for the removal of methylene blue (MB), crystal violet (CV), and Congo red (CR) from an aqueous solution in single and mixture binary systems. The low-cost adsorbent was characterized by FTIR and SEM analysis. The effects of AS dose, contact time, initial dye concentration, pH, and temperature on MB, CV, and CR adsorption were studied in a single system. In a binary system, the MB, CV, and CR were removed from the mixture of MB+CR, CV+MB, and CV+CR with a percentage in volume ranging from 0 to 100 % in MB and CV, and CR. Kinetic studies showed rapid sorption following a second-order kinetic model with of contact time of 10 min. The modulation of adsorption isotherms showed that retention follows the Langmuir model. The thermodynamic parameters proved that the MB, CV, and CR adsorption process was feasible, spontaneous, and exothermic. The synergy adsorption between dyes in a binary mixture of MB+CR and CV+CR, while the competition adsorption between dyes in a binary mixture of MB+ CV.

Super and Selective Adsorption of Cationic Dyes onto Carboxylate-Modified Passion Fruit Peel Biosorbent.

The carboxylate-functionalized passion fruit peel (PFPCS) was an efficient and rapid biosorbent for wastewater treatment. The PFPCS exhibited excellent selectivity to the cationic dyes, where the maximum adsorption capacities for methylene blue (MB) and methyl violet (MV) were 1,775.76 mg g−1 and 3,756.33 mg g−1, respectively. And the adsorption process of MB and MV on PFPCS reached equilibrium within 20 min. Moreover, the adsorption conditions and mechanisms were investigated. The adsorption process was in good agreement with the pseudo-second-order and Langmuir isotherm models. The adsorption mechanism was also proposed to be electrostatic interaction and hydrogen bond. After six cycles of desorption-adsorption, the removal efficient of MB and MV could be kept above 95%. Thus, PFPCS was considered as a highly efficient absorbent for removing cationic dyes from polluted water due to excellent adsorption characteristics, low cost and environmental friendliness.

Crosslinked carboxymethyl cellulose-hydroxyethyl cellulose hydrogel films for adsorption of cadmium and methylene blue from aqueous solutions

The present work describes the production of carboxymethylcellulose (CMC) -hydroxyethyl cellulose (HEC) hydrogel films using citric acid as a non-toxic crosslinking agent, for a potential application in wastewater treatment. After their synthesis, all films were then characterized through Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), UV-Visible spectroscopy (UV-Vis) and swelling study. During these measurements, the successful crosslinking of the hydrogel film was validated; films also possess good thermal stability, a high transmittance under the visible light region, confirming their transparency, and excellent swelling ability in neutral and in acidic media. Therefore, the as-produced films were then used as a potential adsorbent for the removal of cadmium (Cd) and methylene blue (MB) from concentrated aqueous solutions. The adsorption ability of each film was evaluated thanks to thermodynamic and kinetic studies showing that the adsorption equilibrium was reached within 1h for Cd and 3h for MB. Furthermore, the analysis of the adsorption kinetics highlights that all the data could be fitted by a pseudo-second order model, and the adsorption isotherms could be sufficiently described by Langmuir isotherm model for the two studied pollutants. From this analysis, the maximum adsorption capacities, determined by Langmuir model, are close to 126.58 and 769.23 mg/g for Cd and MB, respectively. Moreover, the sorption capacities of Cd and MB in films both increase with the temperature. According to the thermodynamic parameters, cadmium and methylene blue adsorption processes using tested films are favorable, spontaneous, and endothermic.

A Double cross-linked strategy to construct graphene aerogels with highly efficient methylene blue adsorption performance

A novel lysine and EDA double cross-linked graphene aerogel (LEGA) was constructed. The prepared LEGA was utilized as a methylene blue (MB) adsorbent in the wastewater treatment. It exhibits a three-dimensional interconnected porous structure benefiting dye adsorption. Its compression property is highly enhanced with the addition of lysine. Adsorption isotherm and kinetics of MB onto LEGA were discussed. Their results show that MB adsorption onto LEGA was fitted to follow Langmuir adsorption isotherm model and the pseudo-second-order kinetic model. LEGA has an excellent adsorption capacity towards MB as high as 332.23 mg/g and its MB adsorption process is proved to be an exothermic process. The mechanism for MB adsorption onto LEGA was proposed as the ion exchange, electrostatic interaction, π-π stacking interaction and hydrogen bonding. Thus, LEGA is confirmed to be a sustainable and green MB adsorbent with highly removal efficiency in the treatment of wastewater.

Comparison of adsorption behavior studies of methylene blue by microalga residue and its biochars produced at different pyrolytic temperatures.

The adsorption behaviors of methylene blue (MB) on microalga residue powder (MRP) and biochars derived from microalga residue (MRB) produced at different pyrolytic temperatures were compared. Six biochars were prepared from residual Chlorella sp. and Spirulina sp. at different pyrolytic temperatures in the range of 200-550 °C. The adsorption kinetics, isotherms, thermodynamics, and the effect of pH were studied, and chemical analyses of MB-loaded MRP and MRB were conducted using SEM, FTIR, and XPS techniques. The results found that the pseudo-second-order, Elovich, and Freundlich models could effectively describe the MB adsorption process on MRP and MRB. The thermodynamic results confirmed that the adsorption processes were spontaneous and endothermic. Further, MRP showed an excellent adsorption ability on MB through electrostatic interaction, complexation with oxygen/nitrogen-containing functional groups and π-π interaction. However, massive oxygen-containing functional groups after pyrolysis were lost, leading to a significant decrease in the adsorption capacity of MRB on MB. This phenomenon was further observed with increasing pyrolytic temperature. Overall, this study demonstrated that microalga residue performed better for MB removal compared with their pyrolyzed analogs. Graphical abstract.

Adsorptive removal of cationic methylene blue and anionic Congo red dyes using wet-torrefied microalgal biochar: Equilibrium, kinetic and mechanism modeling.

This study aims to investigate the adsorption behavior of cationic and anionic dyes of methylene blue (MB) and Congo red (CR) onto wet-torrefied Chlorella sp. microalgal biochar respectively, as an approach to generate a waste-derived and low-cost adsorbent. The wet-torrefied microalgal biochar possessed microporous properties with pore diameter less than 2nm. The optimum adsorbent dosage of wet-torrefied microalgal biochar for MB and CR dyes removal were determined at 1g/L and 2g/L, respectively, with their natural pHs as the optimum adsorption pHs. The determined equilibrium contact times for MB and CR were 120h and 4h, respectively. Based on the equilibrium modeling, the results revealed that Langmuir isotherm showed the best model fit, based on the highest R2 coefficient, for both the adsorption processes of MB and CR using the wet-torrefied microalgal biochar, indicating that the monolayer adsorption was the dominant process. From the modeling, the maximum adsorption capacities for MB and CR were 113.00mg/g and 164.35mg/g, respectively. The kinetic modeling indicated the adsorption rate and mechanism of the dyes adsorption processes, which could be crucial for future modeling and application of wet-torrefied microalgal biochar. From the results, it suggests that the valorization of microalgae by utilizing wet-torrefied microalgal biochar as the effective adsorbent for the removal of toxic dyes with an approach of microalgal biorefinery and value-added application to the environment is feasible.

THE EFFECT OF ADSORBENT TYPE AND RATIO ON REMOVAL AND ISOTHERM ADSORPTION OF METHYLENE BLUE

THE EFFECT OF ADSORBENT TYPE AND RATIO ON REMOVAL AND ISOTHERM ADSORPTION OF METHYLENE BLUE. Methylene Blue (MB) is one of the dye that are widely used in the textile industry. The wastewater from textile industry that contain MB can reduce the oxygen level in water bodies. This study aims to determine the efficiency of the adsorbent in MB removal and to analyze the isotherm adsorption. The variations conducted in this research was the type of adsorbent and its ratio. The activated carbon that used as adsorbent was fresh betel nut (Cyrtostachys lakka) activated carbon (A), regenerated betel nut activated carbon (B), and coconut shell activated carbon (Cocos nucifera) (C). The type of adsorbent was AB, AC, and BC with ratio of 1:1, 1:2, 1:3, 2:1, and 3:1. The MB concentration was analyzed by using UV-Vis spectrophotometer. Isotherm adsorption was calculated based on Freundlich and Langmuir. The best results showed that the combination of fresh and regenerated betel nuts (AB) with ratio of 3:1 can remove 97.77% of MB. The adsorption process of MB in aqueous solution followed the Langmuir model with regression over 0.99 and adsorption capacity in the range of 2.14 mg/g - 3.53 mg/g.

Removal of methylene blue from aqueous solution using poly(acrylic acid)/SiO2 and functionalized poly(acrylic acid)/SiO2 composite nanofibers

In this study, poly(acrylic acid)/SiO2 (PAA/SiO2) and mercapto-functionalized poly(acrylic acid)/SiO2 (PAA/SiO2/TMPTMS) composite nanofibers were prepared through a sol-gel/electrospinning method to remove methylene blue (MB) from aqueous solution. The optimum conditions of the electrospinning process were achieved at room temperature at an applied voltage of 22 kV, a distance of the needle to the collector of 15 cm, and a flow rate of 0.005 mL/min. The presence of a characteristic peak at 2557.61 cm−1 in the FTIR spectra exhibited that the mercapto group was successfully incorporated into the PAA/SiO2 composite nanofiber. SEM-EDX, TEM, and BET analysis showed that the diameters of PAA/SiO2 and PAA/SiO2/TMPTMS were 382.5 and 246 nm, respectively, with the surface areas of PAA/SiO2 and PAA/SiO2/TMPTMS were 27.67 and 108.54 m2/g, respectively. The batch adsorption results indicated that the maximum MB adsorption capacity of PAA/SiO2 and PAA/SiO2/TMPTMS composite nanofibers was found to be 400 and 437.78 mg/g, respectively, at pH 10 for 120 min of contact time. The adsorption isotherm and kinetics data showed that MB adsorption onto both PAA/SiO2 and PAA/SiO2/TMPTMS composite nanofibers followed the Langmuir adsorption isotherm and was best described by the pseudo-second order kinetic model. Under the experimental conditions, thermodynamic parameter data indicated that the MB adsorption process onto PAA/SiO2 and PAA/SiO2/TMPTMS composite nanofibers was non-spontaneous and endothermic. Their high adsorption capacities and their ability to be reused in multiple cycles support these composite nanofibers to become a promising adsorbent to be developed for removing MB from wastewater.

Renewable adsorbents from carboxylate-modified agro-forestry residues for efficient removal of methylene blue dye

In this work, three renewable highly effective adsorbents (M-CS, M-CCL, M-CCSD) were prepared from agro-forestry residues (corn stalks (CS), Cinnamomum camphora leave (CCL) and Cinnamomum camphora saw dust (CCSD)) by eco-friendly solvent-free esterification with maleic anhydride (MA) for adsorptive removal of methylene blue (MB). The three carboxyl-rich adsorbents adsorbed MB rapidly and presented remarkable adsorption performance towards MB. The maximum adsorption capacity reached 870, 741, 787 mg/g respectively according to Langmuir isotherm model. The pseudo-second-order kinetics and Langmuir isotherm models were more suitable to descript the adsorption processes of MB on M-CS, M-CCL, M-CCSD. Moreover, electrostatic attraction and ion exchange could be involved in adsorption of MB on M-CS, M-CCL, M-CCSD. The adsorption capacity of M-CS, M-CCL, M-CCSD decreased about 4%, 4%, 3% respectively after 4 desorption-resorption cycles. Therefore, M-CS, M-CCL, M-CCSD can be used as sustainable and promising adsorbents with good reusability for highly effective removal of MB in effluent.

The activated carbon produced from mayan bamboo (Gigantochloa robusta Kurz) and its application as dye removal

Bamboo pyrolysis was carried out at a temperature of 400°C for 4 hours to obtain a carbon as a pyrolysis product. The carbon soaked using potassium hydroxide (KOH) 5.35 M for 24 hours. The carbon obtained heated in a reactor at a temperature of 800°C for 5 hours then washed and neutralized until activated carbon obtained. The characterization of activated carbon conducted based on the Indonesian National Standard (SNI 06-3730-1995). The methylene blue adsorption process using a concentration of 50, 100, 150, and 200 ppm for 120 minutes reaction with the contact time variation are 30, 60, 90, 120,150, and 180 minutes in optimum concentration. The result shows that activated carbon has good quality based on SNI 06-3730-1995. The optimum methylene blue removal by bamboo activated carbon reached 99.77% in 120 minutes reaction and the adsorption type follows Langmuir isotherm.

Surface characterization of maize-straw-derived biochar and their sorption mechanism for Pb2+ and methylene blue.

Biochar derived from straw is a potential low-cost adsorbent for metal ions and organic pollutants, but its practical application is still limited by the adsorption capacity. In this study, the correlation between the biochar’s properties and pyrolysis temperature was explored. The adsorption mechanism was studied by monitoring the changes of biochar properties before and after adsorption using BET, SEM, XPS and FT-IR spectroscopy. The adsorption mechanism was revealed following the adsorption kinetics and the changes in biochar’s properties before and after adsorption. The methylene blue (MB) and Pb2+ adsorption removal efficiency reached 95% at the initial concentration of 125 and 500 mg/L, respectively. Physisorption, chemisorption, and pore filling mechanisms determined the adsorption process of MB and Pb2+ on biochar. The Pb2+ adsorption process was highly affected by chemical co-precipitation at higher pyrolysis temperatures. The appearance of tar particles increased the adsorption rate of Pb2+. The biochar obtained at the pyrolysis temperature at 500, 800 and 900°C proved to be applicable for Pb2+ removal. Chemisorption and porosity dominated the MB adsorption, and biochars produced at pyrolysis temperatures of 200, 800 and 900°C are potential materials for MB removal. This study provides optimal pyrolysis conditions for transforming maize straw into valuable, low-cost materials for the removal of different pollutants.

Facile construction of hierarchical porous ultrafine alumina fibers (HPAFs) and its application for dye adsorption

Abstract In this paper, hierarchical porous ultrafine alumina fibers (HPAFs) with macropore and mesopore are facial constructed via using the simple PTFE emulsion template and electro-blown spinning process. The effect of different calcination temperatures, 500 °C, 800 °C and 1100 °C on the pore structures of the ultrafine alumina fibers and their dye adsorption performances are systemically investigated. Results show that calcination temperature has a significant effect on the fiber morphology and pore structure, which is of vital importance in adsorption performance of the ultrafine alumina fiber. Thereinto, the HPAF obtained at 800 °C (HPAF-800) exhibits obviously hierarchical porous structure and high specific surface area (226.94 m2 g−1), which attributed to the thermal decomposition of PTFE particles and the surfactants or other dispersants in PTFE emulsion. Further investigation indicates that the HPAF-800 has good dye adsorption performance, especially the high dye adsorption rate towards methylene blue (MB) with the dye removal rate reaches 97.65% within 30 min at 25 °C, which is mainly due to its hierarchical porous structure. The HPAF-800 also shows desired adsorption cycle performance and the ability to regenerate easily. The adsorption kinetics research indicates that the MB adsorption process follows the pseudo-second-order kinetic model very well. The mechanism of the HPAF-800 for dye adsorption is also concerned. Compared with common alumina fibers, the HPAF-800 exhibits special adsorption behavior and enhanced dye removal rate, which originate from its surface macropores and the capillary effect induced by inner mesopores. Finally, the HPAF-800 suggests its potential applications in adsorption as well as related areas, such as catalysis and catalyst supports.

Efficient adsorbent derived from Argania Spinosa for the adsorption of cationic dye: Kinetics, mechanism, isotherm and thermodynamic study

In this paper, the wood powder from the shell of Argan nuts was used in raw form, or modified form by Sodium hydroxide, as a new economic and ecologic adsorbent. The effectiveness of these materials was evaluated on Methylene Blue (MB), a cationic dye. Those adsorbents were characterized by using scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR). The effect of contact time (2-180 min), adsorbent dose (0.02- 0.8 g), initial dye concentration (50-500 mg/L), pH (2-10.5), and temperature (24-50°C) on the adsorption capacity was studied in a batch reactor. Result obtained showed that the process of MB adsorption onto both adsorbents is in good agreement with the Langmuir adsorption isotherm (R²=0.99 and qe, exp ≈ qe, cal=14.28 for ASN and 64.62 mg/g for ASNN) and followed the pseudo-second-order kinetic model (R²≈1 and qe, cal ≈ qe, exp). According to the equilibrium study, MB was better adsorbed on the modified powder (Qmax ≈ 70 mg/g) than on the raw powder (Qmax ≈ 14 mg/g). The thermodynamic study gives a negative enthalpy (- 28.70 for ASN and - 60.45 KJ/mol for ASNN), a negative Gibbs free energy (- 13.0 for ASN and -16.5 KJ/mol for ASNN), and negative entropy (- 53.14 for ASN and - 148.04 J/mol/K for ASNN) That confirms that the adsorption reaction is energetically favorable, exothermic and spontaneous. We propose an adsorption mechanism-based to electrostatic attractions and H- bonding interaction. The modified adsorbent was found to be comparable or better than others already studied materials, because of its high adsorption capacity and in only 10 minutes of agitation and its efficiency even after five utilizations.