Methylene Blue Adsorption Process Research Articles

Bioeconomic transformation of bio-oil production wastes: a novel adsorbent material for toxic dye adsorption and optimization of process parameters

In this study, for the first time, an adsorbent material was produced from the waste left behind after the bio-oil production process from Terebinth (Pistacia Terebinthus L.) seeds as part of bioconversion, and the adsorption of the hazardous dyestuff methylene blue from aquatic media was investigated. The characterization of the adsorbent was performed using FT-IR, SEM, and BET analysis. The characterization of methylene blue adsorption was conducted to fully understand its nature, including its kinetics, equilibrium, and thermodynamic works. The maximum adsorption capacity (q max) of the monolayer, as determined from the equilibrium data, was calculated to be 166.07 mg g−1. Additionally, the experimental design method was utilized to determine the optimum conditions of the methylene blue adsorption process under various conditions. This study revealed that activated carbons from Terebinth seeds can be used as an economical and environmentally friendly adsorbent, which is very suitable for the removal of highly toxic dyes.

Thermally modified nanocrystalline snail shell adsorbent for methylene blue sequestration: equilibrium, kinetic, thermodynamic, artificial intelligence, and DFT studies.

In recent years, the quest for an efficient and sustainable adsorbent material that can effectively remove harmful and hazardous dyes from industrial effluent has become more intense. The goal is to explore the capability of thermally modified nanocrystalline snail shells (TMNSS) as a new biosorbent for removing methylene blue (MB) dye from contaminated wastewater. TMNSS was employed in batch adsorption experiments to remove MB dye from its solutions, taking into account various adsorption parameters such as contact time, temperature, pH, adsorbent dosage, and initial concentration. SEM, EDS, XRD, and FTIR were used to characterize the adsorbent. The study further developed and adopted adaptive neuro-fuzzy inference system (ANFIS) and density functional theory (DFT) studies to holistically examine the adsorption process of MB onto the adsorbent. EDX and FTIR confirm the formation of CaO with a sharp peak at 547 cm-1, and C-O and O-H are present, as well. SEM and XRD show an irregularly shaped highly crystalline nanosized (65 ± 2.81 nm) particle with a lattice parameter value of 8.611617 Å. The adsorption efficiency of 96.48 ± 0.58% was recorded with a pH of 3.0 and an adsorbent dose of 10 mg at 30 °C. The findings from the study fit nicely onto Freundlich isotherms, with Qm = 31.7853 mg g-1 and R2 = 0.9985. Pseudo-second-order kinetics recorded the least error value of 0.8792 and R2 = 0.9868, thus indicating chemisorption and multilayer adsorption processes. The exothermic and spontaneous nature of the adsorption process are demonstrated by ΔH° and ΔG°. The performance of the ANFIS-based prediction of removal rate, which was demonstrated by a root mean square error (RMSE) value of 2.2077, mean absolute deviation (MAD) value of 1.1429, mean absolute error (MAE) value of 1.8786, and mean absolute percentage error (MAPE) value of 2.0178, revealed that the ANFIS model predictions and experimental findings are in good agreement. More so, DFT provides insights into the molecular interactions between MB and the adsorbent surface, with a calculated adsorbate-adsorbent binding affinity value of -1.3 kcal mol-1, thus confirming the ability of TMNSS for MB sequestration. The findings of this study highlight the promising potential of thermally modified nanocrystalline snail shells as sustainable and efficient adsorbents for MB sequestration.

The production of a novel adsorbent from forest waste (Platanus orientalis L.) for dye adsorption: Adsorption process optimization and experimental design

In the study, a novel activated carbon material was produced using forest waste commonly found in nature. The activation was completed by modifying the surface of the material with H3PO4. Using this adsorbent material, we investigated the adsorption of the hazardous dyestuff, methylene blue, from the water environment. The adsorbent was characterized using BET, SEM, and FT-IR analyses. The characterization processes revealed that the adsorbent has a wealth of functional groups and many cavities and protrusions on its surface. Moreover, according to the BET analysis result, it was observed that it is an adsorbent with a high surface area (876.01 m2 g−1). Kinetic, equilibrium and thermodynamic studies have been conducted to fully understand the nature of methylene blue adsorption. The pseudo-second order kinetic model best represents the adsorption process data, and the Langmuir isotherm aligns with the equilibrium data. According to the Langmuir isotherm data, the maximum adsorption capacity (qmax) was determined to be 198.01 mg g−1. The thermodynamic results showed that the process of adsorption of methylene blue on various surfaces is spontaneous and occurs via physisorption. Additionally, in addition, the effects of the parameters (adsorbent dose, time, and concentration) determined for the methylene blue adsorption process were optimized using the surface response method. Activated carbon from plane tree fruits (Platanus orientalis L.) has the potential to be a novel adsorbent due to its unique surface morphology and strong adsorption capabilities.

Wastewater sludge-derived hydrochar: Effect of operating conditions, activation, and potential use as adsorbent

Scientific management of wastewater sludge generated from biological wastewater treatment is necessary owing to its high moisture content and poor dewaterability. In this investigation, hydrothermal carbonization technique was implemented as a potential solution for wastewater sludge management. To further improve the surface properties of wastewater sludge-derived hydrochar (synthesized at 250 ℃ for 4 h of reaction time), three activation techniques, namely physical, alkali, and alkali followed by acid activation were implemented. The effect of three activation techniques on the properties of hydrochar was investigated using physico-chemical characterization techniques. The sludge-derived hydrochar activated with KOH (1:1 by weight) followed by HCl treatment (1 M) (HC-KA) showcased highly porous structured material having a surface area of 1119 m2 g–1, which was highest amongst the other activation methods chosen in this investigation. Thus, HC-KA was utilized as an adsorbent to evaluate the adsorptive removal of methylene blue (MB). The MB adsorption process followed Langmuir isotherm (R2 of 0.996) with a maximum adsorption capacity of 192.7 mg g–1 and pseudo-second-order reaction kinetics. The results demonstrated that wastewater sludge-derived activated hydrochar can be considered a promising material as an adsorbent in wastewater treatment.

Preparation of a Novel Lignocellulose-Based Aerogel by Partially Dissolving Medulla Tetrapanacis via Ionic Liquid.

A novel lignocellulosic aerogel, MT-LCA, was successfully prepared from MT by undergoing partial dissolution in an ionic liquid, coagulation in water, freezing in liquid nitrogen, and subsequent freeze-drying. The MT-LCA preserves its original honeycomb-like porous structure, and the newly formed micropores contribute to increased porosity and specific surface area. FT-IR analysis reveals that MT, after dissolution and coagulation, experiences no chemical reactions. However, a change in the crystalline structure of cellulose is observed, transitioning from cellulose I to cellulose II. Both MT and MT-LCA demonstrate a quasi-second-order kinetic process during methylene blue adsorption, indicative of chemical adsorption. The Langmuir model proves to be more appropriate for characterizing the methylene blue adsorption process. Both adsorbents exhibit monolayer adsorption, and their effective adsorption sites are uniformly distributed. The higher porosity, nanoscale micropores, and larger pore size in MT-LCA enhance its capillary force, providing efficient directional transport performance. Consequently, the prepared MT-LCA displays exceptional compressive performance and efficient directional transport capabilities, making it well-suited for applications requiring high compressive performance and selective directional transport.

Preparation of MgAl-LDHs loaded with blast furnace slag and its removal of Cu(II) and methylene blue from aqueous solution

ABSTRACT Blast furnace slag (BFS) is a kind of waste produced in industrial production, as well as a valuable secondary resource. In this paper, layered double hydroxides composites (BFS/LDHs) were prepared by aqueous polymerization, with industrial waste BFS as modifier and magnesium nitrate, aluminium nitrate, and urea as raw materials. BFS/LDHs have been characterized by using scanning electron microscopy (SEM), fourier infrared spectrometer (FT IR), x-ray diffraction (XRD), and the specific surface area analyser (BET). The adsorption of BFS/LDHs on Cu (II) and methylene blue (MB) was investigated by batch experiments. The results showed that the adsorption capacity of BFS/LDHs to Cu (II) is stronger than that of MB. What’s more, the solid concentration effect was found in the process of sorption kinetics and sorption isotherms. The sorption kinetics curves of Cu (II) and MB on BFS/LDHs were well fitted by the quasi-second-order kinetics under different adsorbent concentrations. Langmuir and Freundlich sorption isotherm models were used to analyse the adsorption. It showed that the adsorption conforms to Langmuir and Freundlich’s adsorption isotherm models. The BFS/LDHs composites have good recycling availability in this adsorption process of Cu (II) and MB, the removal capacity of which was reduced by 16.1% and 3.8% after being recycled for six times, respectively. More importantly, BFS/LDHs composites are not only expected to become a sewage treatment agent, but also to solve the problem of industrial waste treatment, which is a win–win strategy.

Elimination of a basic dye in liquid waste: an alternative to recycle siliceous by-products of kaolin in the adsorption process of methylene blue

Elimination of a basic dye in liquid waste: an alternative to recycle siliceous by-products of kaolin in the adsorption process of methylene blue

A Statistical Physics Approach to Understanding the Adsorption of Methylene Blue onto Cobalt Oxide Nanoparticles.

The production of cobalt oxide nanoparticles and their use in the adsorption of methylene blue (MB) from solution is described in the paper. The X-ray diffraction patterns show that the synthesized cobalt oxide nanoparticles have a crystalline cubic structure. The study of the adsorption of methylene blue onto the cobalt oxide nanoparticles involved determining the contact time and initial concentration of the adsorption of MB on the adsorbent. The kinetics of adsorption were analyzed using two kinetic models (pseudo-first order and pseudo-second order), and the pseudo-second-order model was found to be the most appropriate for describing the behavior of the adsorption. This study indicates that the MLTS (monolayer with the same number of molecules per site) model is the most suitable model for describing methylene blue/cobalt oxide systems, and the parameter values help to further understand the adsorption process with the steric parameters. Indicating that methylene blue is horizontally adsorbed onto the surface of the cobalt oxide, which is bonded to two different receptor sites. Regarding the temperature effect, it was found that the adsorption capacity increased, with the experimental value ranging from 313.7 to 405.3 mg g-1, while the MLTS predicted 313.32 and 408.16 mg g-1. From the thermodynamic functions, high entropy was found around 280 mg L-1 concentration. For all concentrations and temperatures examined, the Gibbs free energy and enthalpy of adsorption were found to be negative and positive, respectively, suggesting that the system is spontaneous and endothermic. According to this study's findings, methylene blue adsorption onto cobalt oxide nanoparticles happens via the creation of a monolayer, in which the same amount of molecules are adsorbed at two distinct locations. The findings shed light on the methylene blue adsorption process onto cobalt oxide nanoparticles, which have a variety of uses, including the remediation of wastewater.

Extracting lignin from sugarcane bagasse for methylene blue and hexavalent chromium adsorption in textile wastewater: a facile, green, and sustainable approach.

This study presents the process of extracting lignin from sugarcane bagasse collected in the Mekong Delta, Vietnam by the alkali method. NaOH has been used as an effective, environmentally friendly chemical to enhance the extraction process. The obtained lignin was applied for methylene blue (MB) and hexavalent chromium (Cr(vi)) removal. Factors influencing lignin extraction and adsorption processes of MB and Cr(vi) were investigated, showcasing the sustainable reusability of lignin extracted from sugarcane bagasse. Lignin characterization was also carried out by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA) techniques. The results showed that the extracted lignin content reached 38.61% under optimal conditions (NaOH concentration of 10%, reaction temperature of 90 °C and reaction time of 90 min). The adsorption efficiency and capacity of lignin reached 90.90% and 9.09 mg g-1 for MB and 80.10% and 28.04 mg g-1 for Cr(vi), respectively, under optimum adsorption conditions (pH, adsorption time, initial methylene blue concentration, and used lignin content). The adsorption process obeyed Langmuir adsorption and was principally physical adsorption. These findings prove sugarcane bagasse based lignin as a cheap and efficient adsorbent for MB and Cr(vi) removal, which contributes to the utilization of the abundant agricultural by-product for wastewater treatment.

Adsorption behavior and mechanism of modified Pinus massoniana pollen microcarriers for extremely efficient and rapid adsorption of cationic methylene blue dye

Herein, a novel biosorbent was successfully fabricated through a two-step process employing Pinus massoniana pollen as raw material. The efficacy of this biosorbent in eliminating methylene blue (MB), a typical organic cationic dye, from highly concentrated industrial wastewater was investigated. The results demonstrated that by adjusting the wettability of pollen microcarriers, it is possible to significantly increase their adsorption capacity for cationic dyes, resulting in a remarkable 25-fold improvement. The modified Pinus massoniana pollen microcarriers (MPPMC) exhibited an optimal adsorption capacity (585 mg/g) under specific conditions and a rapid equilibrium (97.6% in 5 min, uptake 487.8 mg/g) even at room temperature, showing excellent performance in removing MB efficiently and quickly. It is worth noting that the modified microcarriers could be regenerated via a simple pH-controlled adsorption-desorption cycle, maintaining their superior efficiency (> 99%) even after undergoing five cycles, indicating their excellent reproducibility. The MB adsorption process on MPPMC obeyed the pseudo-second-order kinetic model and followed the Langmuir model. Through the introduced modifications, the substantial deprotonation of carboxyl groups notably augmented electrostatic and hydrogen bonding interactions between MPPMC and MB. Overall, this study offers a sustainable, eco-friendly biological adsorbent, and the MPPMC exhibit the considerable potential for efficient and rapid removal of organic cationic dyes in wastewater.

Modelling and Optimization of Methylene Blue Adsorption Process on Leonurus cardiaca L. Biomass Powder

The main objective of this study was to optimize the adsorption process of methylene blue on a natural, low-cost adsorbent, Leonurus cardiaca L. biomass powder, in order to maximize dye removal efficiency from aqueous solutions. For this purpose, the Taguchi method was used based on an L27 orthogonal array design considering six controllable factors at three levels. The percentage contribution of each factor was computed using analysis of variance (ANOVA). The optimal adsorption conditions were established. The experimental data from equilibrium and kinetic studies were modelled using specific equilibrium isotherms and kinetic models. Thermodynamic parameters were calculated in order to determine the main adsorption mechanism. The obtained results showed that the ionic strength is the factor that most influences dye adsorption (percentage contribution 72.33%), whereas the adsorbent dose had the least impact. The Sips isotherm and the general kinetic model most accurately characterized the process. The maximum adsorption capacity 103.21 (mg g−1) indicated by the Sips isotherm and the equilibrium time (40 min) were better compared to the values obtained for other bio-adsorbents used for methylene blue adsorption. The main mechanism involved in the adsorption is physisorption, while chemisorption only contributes marginally to the process.

Removal of Methylene Blue by adsorption onto natural and purified clays: Kinetic and thermodynamic study

The present work explores the optimization of experimental conditions for the adsorption of the organic cationic dye methylene blue (MB) by natural and purified clays. The adsorption capacities of samples were determinate to evaluate the efficiency of the purification process. At first, we performed mineralogical and textural analysis of the clay minerals, namely, smooth clay (SC), rigorous clay (RC) and bentonite clay (BC), using various techniques, particularly, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray fluorescence (XRF). The characterizations data showed that SC and RC are mainly composed of smectite associated with kaolinite, illite and chlorite. While BC is considered a mesoporous and swelling clay with smectite as the major component. The cation exchange capacity (CEC) was determinate as a 6.30 meq/100 g, 10.69 meq/100 g and 32.64 meq/100 g for SC, RC and RC natural samples respectively. It was noticed that the CEC as well as the specific surface area increase once the impurities associated with the clay are removed. A preliminary study was carried out to elucidate the influence of different parameters; such as contact time, exchangeable cation, solute concentration, temperature and pH on MB adsorption in aqueous solution by clays. The adsorption equilibrium data were analyzed by the linear and nonlinear forms of the Langmuir and Freundlich isotherm models. The Langmuir isotherm fitted well with the experimental data, and the pseudo-second-order kinetic model represented appropriately the adsorption kinetics of MB dye. Moreover, purified clays showed improved adsorption capacity for MB compared to pristine ones: 147.64; 257.69 and 1383 mg/g versus 128.75; 193.4 and 681.85 mg/g for SC, RC and BC respectively. This is attributed to a suitable specific surface, ion exchange capacity and electrostatic interactions as result of a more adequate texture and composition of our treated clays. The thermodynamic studies reveled negative Gibbs free energy change (ΔG) values (from -6.293 to -18.608 KJ.mol−1), positive enthalpy change (ΔH) values, exceeding 40 kJ/mol and positive entropy change (ΔS) values confirming the spontaneous, endothermic and chemisorption nature of the MB adsorption process. The results show that the tested purified clays are efficient in MB removal and can be used as an alternative to the commercial adsorbents, which are often relatively expensive.

Performance of Coconut-shell Activated Carbon on Methylene Blue Treatment

Coconut shell was chosen as a raw material to synthesize activated carbon through physical and chemical activation methods and to evaluate the performance of methylene blue treatment Physical activation method was done by heating the coconut shell in the furnace at 400°C and the chemical activation method was done by using phosphoric acid. Prepared coconut-shell activated carbon (CSAC) was analysed using Fourier-transform infrared spectroscopy (FTIR) to determine the presence of functional groups and their composition. Methylene blue (MB) was chosen as a dye that can be considered as a major pollutant in textile industries’ wastewater. It is a toxic and carcinogenic dye that is harmful to organisms that are exposed to or consumed. The adsorption method using CSAC was used to treat methylene blue due to its higher MB removal efficiency. In this study, methylene blue samples were treated using different dosages of CSAC (15g, 20g, 25g). Color removal (CR%) analysis, COD analysis, and turbidity analysis were done to evaluate the performance of CSAC on methylene blue treatment. 95.59%, 97.40%, and 98.23% of color removal (CR%) were achieved using CSAC dosages of 15g, 20g, and 25g respectively. For COD analysis, 55.41%, 64.33%, and 80.25% of COD removal (%) were achieved when 15g, 20g and 25 g of CSAC dosages were used. 81.48%, 85.19%, and 92.59% of turbidity removal (%) were achieved using CSAC dosages of 15g, 20g, and 25 g respectively. Hence, the adsorption process of MB increases when the dosage of CSAC increases due to surface areas present in the sample.

Preparation of reusable hydrogel spheres based on sodium alginate/Fe3O4 modified with carboxymethyl Huangshui polysaccharide and the efficient adsorption performance for methylene blue

This study successfully constructed a novel multifunctional bio-adsorbent using sodium alginate (SA), ferroferric oxide (FFO), and carboxymethyl Huangshui polysaccharide (CMHSP) with rapid separation, pH sensitivity, efficient adsorption, and reusability for enhancing the removal of methylene blue (MB) in wastewater. FTIR, XRD, SEM, and VSM results indicated CMHSP improved the porosity of the hydrogel spheres, thus significantly enhancing the MB adsorption capacity with the rate-limiting controlled by chemical adsorption, intraparticle diffusion, and film diffusion. The maximum adsorption capacity obtained from Langmuir model of SA-FFO-CMHSP (186.57 mg/g) was obviously higher than that of SA-FFO (178.82 mg/g). Thermodynamic results showed that the MB adsorption process was endothermic, spontaneous, and favorable, and physical adsorption was dominant. Remarkably, MB adsorption maintained 87% ∼ 95% of the initial after four adsorption–desorption cycles, and proper carboxymethylation was conducive to MB adsorption over a broader range pH. These findings provided reference for designing new efficient bio-adsorbents and the recyclable utilization of Huangshui by-products, which was of great value.

Facile preparation of graphene oxide-based composite aerogel to efficiently adsorb methylene blue

With acrylamide (AM), diethylenetriaminepentaacetic acid (DTPA), chitosan (CS), and graphene oxide (GO) as the raw materials, a GO-based composite aerogel named as APAM/DTPA-CS/GO (APAM = Anionic polyacrylamide) was constructed by a facile method. The composite aerogel was systematically characterized by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction to confirm the successful preparation. Methylene blue (MB) was used as the model dye molecule to evaluate the adsorption behaviors of APAM/DTPA-CS/GO. The results showed that equilibrium adsorption capacity of the aerogel toward MB could attain 652.99 mg/g at 303 K, which was more efficient than many previously reported adsorbents. The main driving forces of adsorption process were electrostatic interaction, hydrogen bond, and π-π conjugate interaction. The adsorption process of MB by the composite aerogel could be well described by pseudo-second-order kinetic model and Langmuir isothermal model. APAM/DTPA-CS/GO still maintained high equilibrium adsorption capacity of more than 600 mg/g toward MB even after six adsorption-desorption cycles, indicating that the aerogel had excellent regenerability. The efficient and recyclable adsorption performances might endow GO-based composite aerogel with considerable application prospect in the treatment of dye wastewater.

Easy Recovered Magnetic Bark Biochar for Methylene Blue Removal: Preparation Characterization and Adsorption Parameters Study

AbstractIn this study, two types of magnetic biochars (Magnetic Bark Biochar with protocol 1 (MBB1) and Magnetic Bark Biochar with protocol 2 (MBB2)) were synthesized using pristine poplar bark biochar (PBB) via co‐precipitation. The two prepared magnetic biochars were tested to investigate the aqueous methylene blue (MB) removal performances. MB dye was used as a common pollutant for biochar quality evaluation and the obtained performance in this work was compared with literature. Different analysis techniques such as Scanning Electron Microscope (SEM), Energy Dispersive X‐ray Spectroscopy (EDS), Brunauer‐Emmett‐Teller (BET), porosimetry, Raman spectrometry and Fourier Transform Infrared spectroscopy (FTIR) were used to characterize the obtained materials. Biochars have a microporous structure with an average pore diameter of less than 0.26 nm. Magnetization of bark biochar leads to a loss in specific surface area (from 263.45 m2/g for PBB to 39.22 and 73.02 m2/g for MBB1 and MBB2, respectively) and an increase in total porosity by 85.11 and 12.72 %, respectively. MB adsorption process on MBB1 and MBB2 was best described by the pseudo‐first‐order kinetic model (R2=0.98) and by pseudo‐second‐order kinetic model for PBB (R2=0.9). The Langmuir monolayer adsorption and Marczewski‐jaroniec (M‐J) models presented the best fit for both PBB and MBB2 showing favourable adsorption process. Based on maximum adsorption capacity (qm: 32.98 mg/g) and the highest R2 value (0.96), MBB1 adsorption isotherm was well described by Langmuir model. Isotherm study revealed that MBB2 has the highest adsorption capacity of 49.02 mg/g followed by PBB with 37.85 mg/g. MB‐biochar interactions are dominated by chemisorption regarding the PBB and by physisorption concerning the magnetic biochars.

Enhancing adsorption capacity of magnetic magnesium-aluminum layered double hydroxide by surface modification with sodium dodecyl sulfate for efficient removal of organic contaminants

A magnetic magnesium-aluminum layered double hydroxide (Mag-MgAl) was prepared, and its surface was modified using surfactant sodium dodecyl sulfate (SDS) and utilized as adsorbents for antibiotic ciprofloxacin (CIP) and dyes ponceau red (PR) and methylene blue (MB). Mag-MgAl/SDS demonstrated twice the adsorption capacity for CIP compared to Mag-MgAl, confirming that the surface modification by SDS aided the adsorption capacity. At pH 3.5, Mag-MgAl removed CIP and PR, attributed to electrostatic effect and hydrogen bonding, whereas it did not interact with MB. Conversely, Mag-MgAl/SDS successfully removed both MB and CIP, suggesting that SDS micelles acted as nanoreactors attracting cationic contaminants. The PR removal efficiency was low, possibly due to electrostatic repulsion. A binary dye system adsorption assessment was performed by mixing MB and PR aqueous solutions with Mag-MgAl and Mag-MgAl/SDS as selective adsorbents. Mag-MgAl removed around 80% of PR and 45% of MB, whereas Mag-MgAl/SDS removed less than 40% of PR and 80% of MB. SDS remains adsorbed on the surface of Mag-MgAl/SDS after the adsorption process of CIP, MB, or PR. The inversion in the affinity for the target molecules suggests that the surface of the composite can be adjusted to modulate the behavior of the adsorbent toward organic contaminants.

Harnessing Prunella vulgaris L. residues for enhanced biosorption of dyes in wastewater

Wastewater containing hazardous dyes, such as methylene blue (MB) and malachite green (MG), poses a significant threat to both the aquatic environment and human health. Therefore, timely treatment of dye wastewater is crucial prior to its discharge into the environment. In this research, Prunella vulgaris L. residues obtained from decoction were selected as a novel raw adsorbent for the efficient removal of methylene blue (MB) and malachite green (MG) from aqueous solutions. The four operational factors, namely adsorbent dosage, initial concentration of target dyes, solution pH, and contact time were optimized using Box-Behnken design of response surface methodology. Under the optimized conditions, the adsorbent demonstrated significantly improved removal efficiency for both MB and MG, achieving 99.62% and 93.29%, respectively. Furthermore, the Freundlich model (Adjusted R2 of MB = 0.9757 and Adjusted R2 of MG = 0.9881) and pseudo-second-order kinetic equation (Adjusted R2 of MB and Adjusted R2 of MG both exceeded 0.9700) were found to accurately describe the adsorption processes of MB and MG, indicating that their adsorption behaviors exhibited favorable multilayer nonuniformity primarily governed by physicochemical interactions. The maximum adsorption capacities of MB and MG in aqueous solutions on the adsorbent were found to be 238.84 and 300.42 mg·g−1, respectively. The adsorption mechanisms of MB and MG on the adsorbent were confirmed through various techniques including SEM, EDS, N2 adsorption-desorption test, Zeta potential class, XPS and FT-IR analysis. These mechanisms include electrostatic adsorption, pore filling, ion exchange, hydrogen bonding, and π-π interaction between the adsorbent and MB/MG. In summary, the residuals of Prunella vulgaris L. after decoction can be considered as a potentially efficient adsorbent material for the removal of MB and MG from aqueous solutions, offering a novel approach to regeneration of Chinese herbal residue.

Investigation on the methylene blue adsorbability of biomass carbon derived from orange peels

This study exposes the low-cost adsorbent with the preparation of nanoparticle carbon from orange peel. The orange peels were subjected to pyrolyze from 700 oC to 900 oC for 5 hours in argon gas. FTIR, Raman, TEM and BET methods characterized the effects of functional groups and surface area of adsorbents. The carbon was used for methylene blue (MB) adsorption from an aqueous solution. Various parameters affecting the adsorption process were investigated, including pH (2 ÷ 10) and initial MB concentration (100 ÷ 300 mg/L). The optimum pH of 4.0 for MB adsorption was obtained. A period of 4 hours was required to reach the equilibrium adsorption of MB. The adsorption process of MB on the carbon from orange peel is consistent with the Langmuir isotherm model.

Investigation on Methylene Blue Dye Adsorption in Aqueous by the Modified Mussel Shells: Optimization, Kinetic, Thermodynamic and Equilibrium Studies.

This study assessed the methylene blue adsorption using natural and modified mussel shell powders in the aqueous solution. The mussel shell samples were processed in a NaClO solution then modified with sodium dodecyl sulfate and ethylenediaminetetraacetic acid. The characteristics of mussel shell samples before and after modification were demonstrated using infared spectroscopy, thermogravimetric analysis, scanning electron microscopy, nitrogen adsorption/desorption, energy dispersive X-ray, water contact angle, and dynamic light scattering methods. Some factors such as the pH of the medium, adsorption temperature, and adsorption time had a significant effect on the methylene blue adsorption of mussel shell samples. The adsorption isotherm models and kinetics of methylene blue adsorption by mussel shell samples were also studied. A quadratic regression equation was selected with experimental planning following the Box-Behnken model combined with Design Expert 11.1.0.1 software to optimize the methylene blue adsorption process by mussel shell samples. These results open a promising direction for using naturally derived materials to remove organic pollutants from contaminated water.