Maximum Methylene Blue Removal Research Articles

Preparation of cellulose-based composite hydrogels for the removal of methylene blue

The discharge of dyes, including methylene blue (MB), contributes to environmental pollution. Adsorption is one of the most widely used techniques for removing colorants from water, with hydrogels being the materials that have attracted the most attention due to their excellent adsorption capacity. In this work, hydrogels composed of cellulose/pectin/starch were synthesized to remove MB dissolved in water. For the characterization of the hydrogel, Fourier-Transform Infrared, Thermogravimetry/Differential Thermal Analysis, XRD, and Scanning Electron Microscopy techniques were applied. At pH 9, the maximum swelling capacity (326.1%) of the hydrogel and the maximum MB removal percentage (37.05%) were obtained. The Weber-Morris diffusion kinetic model indicated that other adsorption mechanisms exist in addition to the diffusion process of MB through the hydrogel pores. Temkin's model better described the adsorption process, therefore an interaction between the adsorbate and the adsorbent surface is assumed, while the MB adsorption kinetics at pH 5 followed a pseudo-first-order model; and at pH 7 and pH 9, they followed a pseudo-second-order model.

Effect of Hydrochar Modification on the Adsorption of Methylene Blue from Aqueous Solution: An Experimental Study Followed by Intelligent Modeling

Wheat straw, which is a carbon-rich precursor and a common agriculture waste in Sanandaj, was modified to produce hydrochar with high adsorption capacity by the hydrothermal carbonization (HTC) method. The hydrochars were tested as adsorbents to remove methylene blue (MB) from aqueous solution, and the effects of various interfering parameters, including pH, MB concentration, and adsorbent dosage, were investigated using artificial neural networks (ANNs) on adsorption modeling. Adsorption isotherms and kinetics were studied to explain the MB adsorption process. The prepared hydrochars were characterized using Brunauer–Emmett–Teller (BET), scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDAX), and high-performance liquid chromatography (HPLC) instruments. The maximum MB removal efficiency achieved by hydrochar modified by KOH (0.1 M) and adsorption data fitted well with the Langmuir isotherm and pseudo-second-order kinetics. In terms of elemental composition, the hydrochar sample contained 52.19% carbon (C), 3.37% hydrogen (H), 0.1% nitrogen (N), 0.15% sulfur (S), and 35.66% oxygen (O). The ash content in the sample was 8.50%. The recorded hydrogen-to-carbon ratio (H/C) and oxygen-to-carbon ratio (O/C) indicated a shift towards humification, implying the influence of KOH addition during the hydrochar production process. Additionally, the specific surface area of the hydrochar, as measured by the BET method, was found to be 11.54 m²/g. Among the aromatics, a significant presence of hydroxymethylfurfural (HMF) was detected, with a concentration of 4.70 g/kg DM. The modeling results demonstrated that the concentration of MB had the most substantial impact on the predicted removal, followed by pH, adsorbent dosage, and contact time.

Investigation of kinetics, isotherms, thermodynamics and photocatalytic regeneration of exfoliated graphitic carbon nitride/zeolite as dye adsorbent

A novel exfoliated graphitic carbon nitride and clinoptilolite nanocomposites (Ex.g-C3N4/CP and g-C3N4/CP with a various ratios of g-C3N4 to CP) were prepared by facile method. This study evaluates the adsorption of methylene blue (MB) on the surface of synthesized adsorbents. The as-prepared composites were characterized by XRD, FT-IR, FESEM, BET and DRS. Batch experiments were carried out under various conditions, such as the amount of adsorbent and solution pH. The optimum batch experimental conditions were found under the response surface methodology. The Ex.g-C3N4/CP presented maximum removal of MB as compared to others. The removal efficiency of the as-prepared nanocomposite was significantly elevated owing to the synergistic effects. The adsorption capacities of MB (10 ppm) on Ex.g-C3N4/CP was 54.3 mg/g. The adsorption process by both composites (g-C3N4/CP and Ex.g-C3N4/CP) showed well-fitting with the Elovich kinetic model, and Langmuir isotherm. The thermodynamic study suggested that the adsorption of MB was a spontaneous and endothermic process. The reusability of g-C3N4/CP1:2 and Ex. g-C3N4/CP in removing of MB (10 ppm, pH = 9) was studied by photocatalytic regeneration under visible irradiation for three consecutive cycles. The results obtained from the experimental analyses showed that the removal of MB was easy treatment, eco-friendly, and high yield.

Valorization of spent Aureobasidium pullulans for the removal of toxic pollutant in wastewater treatment

Textile industries are growing rapidly due to increased demand for textile products worldwide. The discharge of textile effluent containing synthetic dyes, chlorides, pigments, aromatic compounds, and heavy metals contributes substantially to water pollution due to its toxicity and chemical composition. This work is focused on the potential usage of treated Aureobasidium pullulans biomass (TAPB) to remove the toxic chemical pollutant, Methylene Blue (MB), from an aqueous solution. Experimental results found that maximum MB removal of 76.5% was observed using TAPB dosage of 3 ​g/L, initial pH 8.0, temperature 30 ​°C, and initial MB concentration of 50 ​mg/L. The maximum biosorption capacity of TAPB was found to be 113.75 ​mg/g using the Langmuir non-linear approach. Successive biosorption and desorption experiments showed better regeneration capacity of TAPB until the fourth trial. These results demonstrated that maximum MB removal (%) could be possible with a small quantity of biomass, consequently offering a minimum size of the contactor and less capital cost requirement for biosorption. It also showed a greater regeneration capacity biosorbent for removing MB. Hence, the feedstock consumption for MB removal could be considerably decreased in large-scale processes.

Biosorption of methylene blue by lentil shell on activation with sulfuric acid, formaldehyde, and calcination: kinetic, isotherm, and thermodynamic study

Lentil shell (LS) on modification with sulfuric acid (LSAC), formaldehyde (LSFM), and on calcination (LSCL) were used for the adsorption of methylene blue dye in the present study. The sulfuric acid treated LS adsorbent has shown maximum adsorption. The batch adsorption experiments were studied with the effect of adsorbent dose (10–60 mg), pH (4–10), dye concentration (10–80 mg/L), contact time (10–60 minutes), and temperature (303–333 K). The maximum removal of methylene blue was found at pH 10 with adsorption time 60 minutes. The maximum adsorption capacity is measured for LSAC, LSCL, LSFM, and LS untreated (LSUN) are 49.56, 45.79, 42.24, and 42.09 mg/g respectively for 60 mg adsorbent dose with 60 mg/L of initial methylene blue dye concentration. The biosorbents were characterized with Fourier Transform Infrared spectra, Scanning Electron Microscopy, Transmission Electron Microscopy, BET-N2 adsorption, and Energy Dispersive X-ray analysis. The adsorption isotherm was studied at the temperature of 303, 313, 323, and 333 K. It was found that the higher temperature suitable for maximum adsorption. Langmuir model and Freundlich model were studied from the obtained results for adsorption mechanism. The pseudo second order kinetic model was found suitable for the present adsorption study in comparison with pseudo first order model and intraparticle diffusion model. The data obtained from the present work showed that LS could be employed as an efficient adsorbent for the adsorption of the dye.

Magnetic coordination polymer for dye removal and antibacterial activity

BackgroundColor elimination from dye wastewater is one of the major environmental concerns, therefore, finding an eco-friendly, recyclable, and effective sorbent for dye treatment is very important. This work aims to scrutinize the performance of a new magnetic amino-coordinated metal–organic framework, namely NiFe2O4/[Zn4(BTC)2(Hbtc)(L-His)2(H2O)4] 1.5H2O (NF/LHTZn), in Acid Red 14 (AR14) and methylene blue (MB) elimination, and antibacterial activity. MethodHere, NiFe2O4 (NF), LHTZn, and NF/LHTZn materials were successfully constructed via the hydrothermal condition and checked via several characterizations (i.e., X-ray diffraction and Fourier transform infrared). Batch adsorption studies were performed to appraise the influence of operational factors like solution preliminary concentration (A), adsorbent dosage (B), contact time (C), temperature (D), and pH on the removal of MB and AR14 dyes. The response surface methodology (RSM) has helped to optimize two dye sorption processes. Significant findingsBased on experimental results, sorption kinetics were correctly matched by the pseudo 2nd order model for both dyes. Freundlich's isotherm indicated that the best fit for MB removal and maximal uptake capacity (Qmax) was 375.93 mg/g, while Langmuir was best fitted for AR14 (Qmax= 276.24). Thermodynamic results revealed that both dye adsorption was spontaneous in nature. According to RSM data, the maximum removal of MB was 292.61 mg/g under optimal conditions, A= 100 mg/L, B= 0.3 g/L, C= 140 min, D= 30 °C and, pH 7, and a maximum AR14 adsorption of 272.35 mg/g gained at an A= 100 mg/L, B= 0.3 g/L, C= 126 min, D= 40 °C and pH 2. Based on disk diffusion results, NF/LHTZn has also a proper antibacterial performance toward Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria.

Methylene Blue Dye Removal from Water by Neem Leaf (Azadirachta indica) Adsorbent

Organic dyes, present in the aquatic environment, have negative effects on ecosystems. Attempts are being made to remove these dyes by using number of physico-chemical methods. Out of all the methods, adsorption technique is the most economical and efficient technique. However, for this purpose, efficient and cost-effective adsorbents are needed. In this paper processed neem leaf powder (NLP) has been used for methylene blue (MB) dye removal. NLP has been characterized by X-ray diffraction, FTIR spectroscopic, and scanning electron microscopic techniques. Results have shown that NLP has crystalline character with number of functional groups. MB is removed by using NLP under different varying conditions such as NLP doses, varying MB concentration, and different pH. When fixed amount of NLP (0.2 g) is used, removal of MB increases with time and becomes almost constant after 40 min. Maximum MB removal is obtained at pH = 6.0. Adsorption isotherms and kinetic models are discussed and the data fitted well with Langmuir isotherm and pseudo second order kinetic models. Ab initio calculations have shown that nature of interaction depends on the orientation of groups and both type of adsorption is feasible in the present system. Results show that NLP is an effective adsorbent for removal of MB dye.

Synthesis of Mil-100(Fe)@Fe3O4 Composite using Zircon Mining Magnetic Waste as an Adsorbent for Methylene Blue Dye

The objectives of the present study are to synthesize MIL-100(Fe)@Fe3O4 composite and to clarify its ability as an adsorbent for methylene blue dye. The magnetite (Fe3O4) was synthesized using iron precursor from the zircon mining magnetic waste. The MIL-100(Fe) was composited with magnetite using a room-temperature in situ synthesis method. The MIL-100(Fe)@Fe3O4 composite obtained was then characterized using the Fourier transform infrared spectroscopy and X-ray diffraction. The synthesized MIL-100(Fe) and MIL-100(Fe)@Fe3O4 were then used to adsorb methylene blue dye from aqueous phase. The maximum methylene blue removal from both adsorbents was obtained at pH of 9. The adsorption kinetics showed that the adsorption followed a pseudo second-order kinetics model with the rate constant values for MIL-100(Fe) and MIL-100(Fe)@Fe3O4 were 1.012 x 10-2 and 3.963 x 10-2 g/mg.menit, respectively. The results also showed that the adsorption isotherm of MIL-100(Fe) and MIL-100(Fe)@Fe3O4 follows the Langmuir isotherm for adsorption capacities were 137.70 and 151.47 mg/g, respectively. The results indicate that the iron content in the zircon mining magnetic waste as precursor for synthesis MIL-100(Fe)@Fe3O4 composite can be employed as an excellent adsorbent for removal of methylene blue dye from aqueous phase.

Mesoporous activated carbon from mangosteen (Garcinia mangostana) peels by H3PO4 assisted microwave: Optimization, characterization, and adsorption mechanism for methylene blue dye removal

This study reported a facile method to synthesize mangosteen peels activated carbon (MSPAC) from an abundant Malaysian biomass waste (mangosteen peels) via microwave-assisted H3PO4 activation. The process resulted in high carbon content and mesoporous structure with a high surface area (681.41 m2/g). MSPAC was applied as an adsorbent for methylene blue (MB) dye removal from aqueous solutions. The response surface methodology approach was established via Box-Behnken Design (BBD) to optimize a series of adsorption conditions: MSPAC dose (0.02–0.06 g), solution pH (3–9), and time (5–20) for MB adsorption. The BBD method indicated that the best adsorption parameters for maximum MB removal are an MSPAC dose of 0.06 g, an MB solution pH of 6, and a time of 20 min. The result showed that the PSO kinetic model best represented the adsorption kinetics, whereas the Langmuir model best characterized the equilibrium results, with the maximal monolayer adsorption capability of 163.6 mg/g for the MB dye adsorption onto MSPAC. Thermodynamic findings demonstrated that MB uptake onto MSPAC was a spontaneous and endothermic process. The results of this work show that quite rapidly manufactured MSPAC is an excellent environmentally friendly adsorbent for removal of cationic synthetic dyes from polluted water.

A study on the uptake of methylene blue by biodegradable and eco-friendly carboxylated starch grafted polyvinyl pyrrolidone

This study is based on the removal of methylene blue (MB) from aqueous solution by cost effective and biodegradable adsorbent carboxymethyl starch grafted polyvinyl pyrolidone (Car-St-g-PVP). The Car-St-g-PVP was synthesized by grafting vinyl pyrolidone onto carboxymethyl starch by free radical polymerization reaction. The structure and different properties of Car-St-g-PVP were determined by 1H NMR, FT-IR, XRD, TGA and SEM. A series of batch experiments were conducted for the removal of MB, The adsorption affecting factors such as temperature, contact time, initial concentration of MB dye, dose of Car-St-g-PVP and pH were studied in detail. The other parameters like the thermodynamic study, kinetics and isothermal models were fitted to the experimental data. The results showed that pseudo 2nd order kinetics and Langmuir's adsorption isotherms were best fitted to experimental data with regression coefficient R2 viz. 0.99 and 0.97. The kinetic study showed that the adsorption mechanism favored chemisorption. The Gibbs free energy (ΔG°) for the adsorption process was found to be −7.31 kJ/mol, −8.23 kJ/mol, −9.00 kJ/mol and −10.10 kJ/mol at 25 °C, 35 °C, 45 °C and 55 °C respectively. The negative values of ΔG° suggested the spontaneous nature of the adsorption process. Similarly, the positive values of entropy (ΔS°) and enthalpy (ΔH°) 91.27 J/k.mol and 19.90 kJ/mol showed the increasing randomness and endothermic nature of the adsorption process. The value of separation factor (RL) was found to be less than one (RL < 1), which supported the feasibility of the adsorption process. The maximum MB removal percentage (% R) was found to be 98.6%. So, these findings show that Car-St-g-PVP can be meritoriously used for the treatment of MB from wastewater.

Biochar from Cyperus alternifolius Linn.: from a waste of phytoremediation processing to efficient depolluting agent.

Phytoremediation is one of the most powerful and viable solutions for developing countries to clean the soil and water bodies from metallic pollutants. Cyperus alternifolius Linn. (CAL), a tropical wetland plant, has been widely researched for removing harmful contaminants due to its hyperaccumulation ability. However, the waste biomass of phytoremediation processing may risk secondary environmental pollution. Thus, the preparation and application of biochar from metal-contaminated plants can be considered a new approach. In a 60-day experiment, CAL plants were irrigated with different concentrations of Zn(II) (200, 700, 1200, 1700, and 2200mg·L-1), and then the plants were converted into biochar via the pyrolysis process. The characteristics of biochar including of surface composition and morphology, phase formation, and optical property were analyzed. The biochar enriched with Zn(II) at 1200mg·L-1 had a bandgap value of 3.17eV and consisted of carbon microparticles intermingled with ZnO and SiO2 nanoparticles. Furthermore, the adsorption and photocatalysis of the biochar were studied in the discolouration of methylene blue (MB), as a test reaction, with the maximum MB removal capacities of 55.2mg·g-1. Such results will serve as the basis for new research aiming at the potential for reusing metal-contaminated plants to produce efficient depolluting biochar.

Modelling and optimization for methylene blue adsorption using graphene oxide/chitosan composites via artificial neural network-particle swarm optimization

Water pollution due to dyes from industrial effluents and domestic wastewater is a big environmental issue, so an effective adsorbent is needed. In this study, graphene oxide/chitosan (GO/CS) composites were synthesized and applied for methylene blue (MB) dye removal. Characterization was done on the GO and GO/CS composites using FTIR, EDX, SEM, and TGA. The adsorption studies were conducted to verify the effect of pH, adsorbent dosage and contact time. The interactive effects of the process variables were verified using response surface methodology (RSM), and optimal conditions for higher adsorption efficiency are evaluated by Artificial neural network (ANN)-Particle swarm optimization (PSO). ANN-PSO predictions are in good agreement with the experimental values and hence resulted in higher R2 (=0.998) compared to RSM predictions (R2 = 0.981). The MB adsorption process is found to be obeying the Langmuir isotherm and pseudo 1st order kinetic model. The maximum MB removal efficiency (90.34%) and adsorption amount (7.53 mg/g) can be obtained at an initial dye concentration of 10 mg/L and optimal values of pH (5), adsorbent dosage (0.143 g/L) and contact time (125 min). These results further confirm that the ANN-PSO-based approach is able to capture the inherent mechanisms of the MB adsorption process and can be used as a good modelling approach.

Natural Sunlight Driven Photocatalytic Removal of Toxic Textile Dyes in Water Using B-Doped ZnO/TiO2 Nanocomposites

A novel B-doped ZnO/TiO2 (B–ZnO/TiO2) nanocomposite photocatalyst was prepared using a mechanochemical–calcination method. For the characterization of the synthesized B–ZnO/TiO2 photocatalyst, XRD, FESEM-EDS, FTIR, UV-Vis DRS, BET, PL, and XPS techniques were used. The bandgap energy of B–ZnO/TiO2 was reduced, resulting in enhanced visible-light absorption. Significant PL quenching confirmed the reduction in the electron–hole recombination rate. Furthermore, reduced crystallite size and a larger surface area were obtained. Hence, the B–ZnO/TiO2 photocatalyst exhibited better photocatalytic activity than commercial TiO2, ZnO, B–ZnO, and ZnO/TiO2 in the removal of methylene blue (MB) dye under natural sunlight irradiation. The effects of various parameters, such as initial concentration, photocatalyst amount, solution pH, and irradiation time, were studied. Under optimal conditions (MB concentration of 15 mg/L, pH 11, B–ZnO/TiO2 amount of 30 mg, and 15 min of operation), a maximum MB removal efficiency of ~95% was obtained. A plausible photocatalytic degradation mechanism of MB with B–ZnO/TiO2 was estimated from the scavenger test, and it was observed that the •O2− and •OH radicals were potential active species for the MB degradation. Cyclic experiments indicated the high stability and reusability of B–ZnO/TiO2, which confirmed that it can be an economical and environmentally friendly photocatalyst.

An Effective Biomass for the Adsorption of Methylene Blue Dye and Treatment of River Water

Neolamarckia cadamba leaves were used as an adsorbent for methylene blue removal as well as for the reduction in the water quality parameters of the sewage belts of Yamuna River in Allahabad, Uttar Pradesh, India. A variety of water quality parameters were assessed, including chemical oxygen demand, biological oxygen demand, total dissolved solids, conductivity, hardness, pH, and temperature. A great deal of degradation in the water quality parameters collected from three locations within the Yamuna River in Allahabad, Uttar Pradesh, India, has been observed by treating with Neolamarckia cadamba leaves. The adsorption studies were carried out by the batch method, and the effect of various parameters such as contact time, pH, initial concentration, and temperature was assessed. The maximum removal of methylene blue was obtained at pH 5 after 120 minutes of equilibrium time. In addition to fitting the Langmuir isotherm most accurately, the adsorbent also followed pseudokinetics of the second order. The maximum monolayer adsorption capacity of used biomass was 101 mg/g using 50 mg/L methylene blue solution. It is evident from the thermodynamic data that the adsorption is exothermic. Also, the spontaneity of the interaction between adsorbent and adsorbate decreases with temperature. Energy-dispersive X-ray spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques were used to characterize the adsorbent. SEM images revealed that the biomass consisted of irregular spherical lumps with a porous structure, which provided effective adsorption sites. A chemical composition analysis of the biomass by EDAX shows that the chemical composition of oxygen and carbon decreases, whereas nitrogen’s chemical composition increases.

Ipomoea carnea: a novel biosorbent for the removal of methylene blue (MB) from aqueous dye solution: kinetic, equilibrium and statistical approach

The biosorption potential of cost-effective and agricultural residue, Ipomoea carnea wood (ICW) was examined by the removal of cationic dye, methylene blue (MB) from aqueous solution. The surface morphology, structural and thermal properties of untreated ICW were analyzed using Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Thermo-gravimetric Analysis (TGA), respectively. The effects of different parameters namely concentration of biosorbent, initial pH, initial MB composition and temperature on biosorption capacity and biosorption (%) were studied. The kinetic and equilibrium models were developed to fit the experimental data on MB biosorption. The maximum biosorption capacity of 39.38 mg g−1 was obtained at 40 °C using Langmuir model. The removal of MB was found to be significantly varying with temperature. Box–Behnken design was applied to optimize the biosorption parameters. The optimized condition for MB biosorption was evaluated as dosage of 3.1 g L−1, pH of 7.04, Temperature of 49.1 °C, MB concentration of 30.48 mg L−1 and maximum biosorption (%) of 83.87. The regeneration of ICW was investigated by five cycles using a suitable eluting agent. Hence, ICW without any pretreatment and chemical modification is a potential candidate for the removal of MB in terms of availability and economy of the process. Novelty statement Ipomoea carnea wood (ICW) without any pretreatment explored a potential biosorbent for the removal of methylene blue (MB) in terms of availability and economy of the process. The physico-chemical properties of ICW characterized using Scanning Electron Microscopy, Fourier transform infrared spectroscopy and Thermo-gravimetric Analysis showed ICW as a promising biosorbent for MB removal. Presence of heterogeneous with rugged morphological structure, cavities, irregular shape and size of large pores provide the better biosorption capability for MB molecules using ICW without any pretreatment or chemical modification. Analysis of kinetic and isotherm models was performed to examine the better fitness of experimental data with model. Thermodynamic parameters indicating feasible and endothermic MB biosorption. Statistical design of experiments is used to optimize the condition and corresponding maximum MB removal using Derringer’s desired function methodology. Untreated ICW is a potential reusable biosorbents, effectively employed in successive biosorption and desorption process for the removal of MB from aqueous solutions.

Preparation of Zeolite 4A for Adsorptive Removal of Methylene Blue: Optimization, Kinetics, Isotherm, and Mechanism Study

In this study, we have reported a facile preparation of zeolite 4A from Ethiopia kaolin for the adsorptive removal of methylene blue (MB) dye. The formation of highly crystalline and pure phase zeolite 4A with cubic morphology was confirmed by powder X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. The efficiency of zeolite 4A for abatement of MB was investigated at varying adsorption parameters. Response surface methodology coupled with Box Behnken Design (RSM-BBD) was employed to optimize adsorption parameters. High regression (R2 = 0.9947) and the low probability (p value <0.0001) values signify the validity of the quadratic model to predict the removal (%) of MB. The maximum MB removal (%) was 99.37% at the optimum combination of 50 mL of 10 mg/L of MB, 39.05 mg zeolite 4A, and 179.82 contact time (min). The adjusted R-square (R2adj) and standard deviations (SD) were validated the best fitting of pseudo-second-order kinetics and the Langmuir isotherm model for experimental values. The maximum adsorption capacity (Qmax) of zeolite 4A towards MB was found to be 44.35 mg g−1. Electrostatic interaction, hydrogen bond, and n to π bond formation are predicted to be the plausible interaction mechanism of MB to the surface of zeolite 4A. The Fukui function and vibration analysis based on the density functional theory (DFT) further strengthened the proposed mechanism.

Biosorption of Methylene Blue Dye from Textile-Industry Wastewater onto Sugarcane Bagasse: Response Surface Modeling, Isotherms, Kinetic and Thermodynamic Modeling

This research focuses on the viability of removing basic dye methylene blue (MB) from water solutions by the application of sugarcane bagasse (SCB), an economic natural biosorbent. Batch experiments were conducted based on solution pH, contact period, initial adsorbate dye concentration, biosorbent amount, and temperature as independent variables by employing a central composite design approach of response surface methodology (RSM). With the use of RSM, the optimization of the MB biosorption process was carried out for maximum MB removal. The biosorption equilibrium of the dye solution was achieved after a contact time of 90 min and explained by the Langmuir and Freundlich isotherms. The biosorption data is employed for the kinetic modeling, from pseudo-first- and pseudo-second-order kinetic equation. Thermodynamic parameters (Enthalpy change ΔH, entropy change ΔS, and Gibbs free energy ΔG) were studied, which showed that biosorption is natural and endothermic in nature by reducing color randomness at the liquid and solid interface. Biosorbent characterization explained in this analysis is performed through Fourier-transform infrared spectroscopy before and after MB biosorption. Characteristic tests and separation factor proved that SCB was able to be used as an option to commercial biosorbents for the aqueous solution and removal of MB from wastewater.

Low-cost biosorption of Methylene Blue and Congo Red from single and binary systems using Sargassum latifolium biorefinery waste/wastepaper xerogel: an optimization and modeling study

There is a growing interest for the utilization of brown macroalgae for integrated production of various value-added products with zero waste generation. Therefore, the biorefinery waste of Sargassum latifolium after the sequential extraction of polyphenols, fucoidan, and alginate was utilized for the preparation of an environmentally benign xerogel using wastepaper. The adsorption efficiency of the xerogel for Methylene Blue (MB) and Congo Red (CR) was successfully evaluated using Box-Behnken experimental design. Under the optimized conditions, the maximum MB removal was 92.54% compared with 94.97% for CR for the single system and for the binary system the maximum bioremoval was 97.16% and 87.66% for MB and CR, respectively. The maximum dye adsorption (qe) for MB and CR in a single system was 8.54 mg g−1 and 20.97 mg g−1 at pH 5.0, respectively, while the qe was reduced in the binary system due to antagonistic interaction. The kinetics of MB and CR biosorption from single and binary systems were better represented by the pseudo-second order model. The adsorption mechanism was predominantly intraparticle diffusion, but the effect of the external mass transfer was significant. Langmuir, Freundlich, Langmuir-Freundlich, and Temkin isotherms were able to represent the experimental data, but they differ in priority depending on dye type and pH. The thermodynamic analysis indicated that the adsorption process was endothermic, except MB in a single system. The developed xerogel is an environmentally benign biosorbent suitable for cationic and anionic dye removal from single or multicomponent dye containing effluents.

Phosphoric acid-treated Spent Tea Residue Biochar for Wastewater Decoloring: Batch Adsorption Study and Process Intensification using Multivariate Data-based Optimization

This work investigates the production of biochars from phosphoric acid-treated spent-tea residue (STR) by pyrolysis at different temperatures. The biochar morphology and chemistry were characterized via SEM, FT-IR, XRD and BET analyses. Results showed that an increase in the pyrolysis temperature could enhance the porous-structure and increase the surface area, whereas it might deteriorate the surface-functional groups to some extent. The produced biochar samples were employed for the adsorption of methylene blue (MB) from water. The batch adsorption process was investigated via a data-based multivariate optimization approach, Pareto sensitivity analysis and response surface methodology (RSM) for the intensification of the process. The STR biochar produced at the pyrolysis temperature of 400 °C offered the maximum MB removal of 99.26% at the optimal operating conditions of pH = 9.65, initial dye concentration = 81.24 mg/L, adsorbent dosage = 0.26 g and contact time = 97.92 min. Pareto sensitivity analysis revealed that the MB adsorption on STR-derived biochar is strongly influenced by pH and contact time. The isothermal and kinetic studies indicated that the adsorption of MB on STR biochar is well described by the Langmuir isotherm and pseudo-second order model, respectively. The adsorption capacity of the optimal biochar was obtained to be 91.13 mg/g.

Adsorption of Methylene Blue from Textile Industrial Wastewater onto Activated Carbon of Parthenium hysterophorus

Many of the basic dyes are non- degradable and toxic pollutants in textile industrial wastewater. Methylene blue (MB) is a cationic dye that exists at a large scale in the textile wastewater which is discharged into the nearby environment without proper management, particularly in developing countries including Ethiopia. Therefore, this study aimed to evaluate the adsorption performance of MB from textile wastewater using locally prepared activated carbon produced from Parthenium hysterophorus stem. The plant samples were activated using H3PO4. The activated carbon was then characterized using proximate analysis, scanning electron microscope and Fourier transform infrared spectroscopy. Batch adsorption studies were conducted to determine the optimum condition for removal of MB from synthetic and real textile industrial wastewater under the effect of pH, contact time, adsorbent dose, and initial MB concentration. The adsorption isotherms were checked using Langmuir and Freundlich isotherms models. The result of the proximate analysis has shown that the activated carbon was composed of 5.7% moisture, 15.3% ash, 18.6% volatile matter and 60.4% fixed carbon. Using an aqueous solution, the maximum MB removal of 94% was achieved at the pH value 11, contact time 100 min, adsorbent dose 2 g in 100 mL and at the initial MB concentration 100 mg/L, whereas the maximum removal of MB from actual textile wastewater was found to be 91%. The Langmuir isotherm model was best fitted with experimental values at R2 was 0.99. Finally, it can be concluded that the activated carbon has a good adsorption capability and promising for MB removal from textile wastewater at an industrial scale.