Methylene Blue Adsorption Capacity Research Articles

Microwave assisted activation of silkworm excrement for fast adsorption of methylene blue and high performance supercapacitor

The activated carbon (AC) with an exceptionally high surface area was made of silkworm excrement (SE) by microwave-assisted KOH activation (MAKA). It was investigated for the potential applications in methylene blue (MB) adsorption and a supercapacitor electrode. The effect of activation time on the AC properties and performance was studied. The physical and chemical properties of the as-prepared samples were analyzed by FE-SEM, TEM, N2 adsorption, and Raman spectroscopy. Remarkably, the AC with the largest specific surface area (SAs) of 2530.3 m2g−1 was produced by partial carbonization of SE at 400 °C (SE400-5) and then activated for only 5 min. The large SAs is attributed to the abundance of micro-pores, leading to the enhanced MB absorption performance, as equilibrium was reached within 10 min at 25 ppm of MB concentration. The maximum MB adsorption capacity for SE400-5 was 902.56 mg g−1. The adsorption isotherms revealed that the Langmuir model best fits the empirical data (R2 ≥ 0.9813), indicating monolayer adsorption. The kinetic model fitted well to the Pseudo-second-order (PSO) (R2 ≥ 0.9691). CV, GCD, and EIS measurements also evaluated the electrochemical properties of all samples. The electrodes were made without the addition of conductive material. The SE400-5 also had the lowest total resistance and highest total effective capacitance, which resulted in its highest specific capacitance (Cs) of 322 F g−1 at 0.5 A g−1. The capacitive retention of SE400-5 remained as high as 98% even after 10,000 cycles at 10 A g−1. These results demonstrate that SE is a viable source of AC for MB adsorption and a supercapacitor electrode.Graphical abstract

Experimental and theoretical insights into the adsorption mechanism of methylene blue on the (002) WO3 surface

This work investigates the efficiency of green-synthesized WO3 nanoflakes for the removal of methylene blue dye. The synthesis of WO3 nanoflakes using Hyphaene thebaica fruit extract results in a material with a specific surface area of 13 m2/g and an average pore size of 19.3 nm. A combined theoretical and experimental study exhibits a complete understanding of the MB adsorption mechanism onto WO3 nanoflakes. Adsorption studies revealed a maximum methylene blue adsorption capacity of 78.14 mg/g. The pseudo-second-order model was the best to describe the adsorption kinetics with a correlation coefficient (R2) of 0.99, suggesting chemisorption. The intra-particle diffusion study supported a two-stage process involving surface adsorption and intra-particle diffusion. Molecular dynamic simulations confirmes the electrostatic attraction mechanism between MB and the (002) WO3 surface, with the most favorable adsorption energy calculated as -0.68 eV. The electrokinetic study confirmed that the WO3 nanoflakes have a strongly negative zeta potential of -31.5 mV and a uniform particle size of around 510 nm. The analysis of adsorption isotherms exhibits a complex adsorption mechanism between WO3 and MB, involving both electrostatic attraction and physical adsorption. The WO3 nanoflakes maintained 90% of their adsorption efficiency after five cycles, according to the reusability tests.

Adsorption Properties of Alkali-activated Stone Wool

Alkali-activated materials are actively studied as adsorbents for toxic metals, nutrients, and dyes from wastewater. They are produced using an environmentally friendly process from low-cost aluminosilicate precursors, and thus have significant potential for fostering the development of clean technology. One of the potential precursors is stone and glass wool, for which alkali activation has been successfully demonstrated in construction products. In this study, alkali-activated stone wool was assessed for adsorption for the first time. Stone wool manufactured without organic resin (SW) and another stone wool with organic resin being removed by heat treatment (SW-O) were alkali activated using NaOH, Na2CO3, NaAlO2, or Na silicate solution, and characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetry–mass spectrometry, and potentiometric titrations to understand the surface properties affecting adsorption. Comparative adsorption experiments were conducted using methylene blue (MB), cobalt (Co(II)), arsenite (As(III)), and NH4+ at 100 mg × L −1 concentration, 1 g/L adsorbent dose, 24 h contact time, and pH of 7. The raw stone wools demonstrated almost no adsorption, whereas the alkali-activated stone wools adsorbed up to 78, 42, 3, and 18 mg × g−1 of MB, Co(II), As(III), and NH4+, respectively. The samples prepared with the SW Na silicate demonstrated higher adsorption capacities for MB and Co(II). For As(III), an adsorption capacity was similar regardless of the mixture. The highest adsorption capacity for NH4+ was achieved with SW-O NaOH. The increased adsorption capacities were related to the increase in the specific surface area, more negative zeta potential, formation of tobermorite-like structures, and an increase in the quantity of surface OH groups. The varying adsorption levels of specified contaminants are possibly governed by their speciation at pH 7, aqueous radii, and the adsorption mechanism. This study demonstrated that stone wool-based adsorbents have practically relevant potential for wastewater treatment.

Effective adsorptive removal of heavy metal anion Cr(Ⅵ) and dye cation methylene blue by the novel 2D material TiVCTx MXene

With the increasingly serious industrial pollution, the effective removal of heavy metal ions and organic pollutants from wastewater has become a key issue of environmental protection. In this paper, a new MXene material, TiVCTx, was prepared by in situ etching, and its adsorption capacity of heavy metal anion Cr(Ⅵ) and methylene blue (MB) dye cation was studied. The effect of adsorption time, pH values, temperatures, initial concentrations of adsorbent and adsorbate, interfering ions on the Cr(Ⅵ) and MB adsorption of TiVCTx was systematically investigated. It is found that TiVCTx has excellent Cr(Ⅵ) and MB adsorption property, the adsorption capacity can be as high as 600mg/g and 1430mg/g, respectively. The adsorption experiments revealed that the adsorption process of Cr(Ⅵ) conformed to the Langmuir isotherm model and the Pseudo-second-order kinetic model, which indicated that the Cr(Ⅵ) adsorption was a heat-absorbing monolayer chemisorption. In contrast, the adsorption process of MB is in accordance with the Freundlich isotherm model and the Pseudo-second-order kinetic model, suggesting that the MB adsorption was an exothermic multilayer chemisorption. The results of X-ray electron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis further confirmed that the reductive adsorption and electrostatic adsorption can account for the outstanding Cr(VI) and MB adsorption capacity of TiVCTx, respectively.

Good adsorption performance for both cationic and anionic dyes by a novel crosslinked tetrafluoroterephthalonitrile-tannic acid-chitosan polymer synthesized via one-pot reaction

In this work, tetrafluorophenonitrile was utilized to crosslink tannic acid and chitosan together to form a new crosslinked polymer (CSTTA), and then the Fe3O4 nanoparticles were prepared and immortalized on the CSTTA at the same time to obtain the Fe3O4/CSTTA composite. The structures of CSTTA polymer and Fe3O4/CSTTA composite were characterized by SEM, FTIR, TGA, 13CNMR, XPS, WAXD, N2 adsorption-desorption isotherm, VSM, and zeta potential measurement. The CSTTA could simultaneously adsorb the cationic methylene blue (MB) and anionic orange G (OG), and its adsorption behaviors for MB and OG conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, which were spontaneous according to thermodynamic calculation. The CSTTA possessed not only high adsorption capacities for both MB and OG up to 1092.69 mg/g and 519.89 mg/g at 303 K under the optimal pH conditions of pH=10 and pH=1, respectively, but also the good reused ability. In addition, the Fe3O4/CSTTA composite could also absorb both MB and OG with good magnetically recollected ability to avoid secondary pollution.

Cnicus Benedictus roots as a low-cost adsorbent for methylene blue dye removal from aqueous solution: kinetic and equilibrium studies

In this research, Cnicus Benedictus roots powder (CBRP) was utilized as a low-cost adsorbent for removing methylene blue (MB) as a cationic dye from aqueous solution. Characterization of CBRP by Boehm titration method, Fourier transform infrared (FT-IR) and environmental scanning electron microscope (ESEM) indicates the presence of different types of functional groups and a very rough surface filled with cavities, suitable for MB adsorption. The effect of various parameters such as CBRP dose (0.2–2 g/1L), contact time (0–180 min), initial pH (1–10), coexisting anions/cations and the initial MB concentration (100–500 mg L−1) on MB adsorption were examined, the results showed that MB uptake depends on the pH of solution, the electrostatic attraction forces, the formation of H-bonds and π–π interactions are the possible CBRP–MB interaction mechanisms. Adsorption kinetic of MB on CBRP was best represented by linear and non-linear form of the pseudo-second order model. The experimental equilibrium data were best described by linear and non-linear forms of Langmuir and Redlich–Peterson isotherm models (R 2> 0.98) with a maximum MB adsorption capacity of 85.47 mg g−1 at 25 °C, the adsorption efficiency R (%) was greater than 90 (%). MB adsorption-desorption experiments showed the reusability of CBRP for five consecutive cycles. According to the obtained results, CBRP can be used as a natural adsorbent material for cationic dyes removal from aqueous solution.

Methylene blue adsorption by chemical-activated Trichanthera gigantea leaf

ABSTRACT This study investigated the potential of NaOH-treated Trichanthera gigantea leaf (TGL) powder as a sustainable, low-cost biosorbent for methylene blue (MB) removal from wastewater. Characterization using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller, and energy-dispersive X-ray spectroscopy (EDX) techniques confirmed favorable morphology, identifying micropores, suitable functional groups, notable surface area, pore volume, and elemental diversity. Batch experiments systematically investigated the influence of operational parameters, including contact time, initial MB concentration (5–35 mg/L), pH (2–10), and biosorbent dosage (2–10 g/L) on adsorption performance. The Langmuir isotherm model best represented the experimental data (R² values of 0.993 and 0.9725), indicating favorable adsorption (RL < 1) and maximum MB adsorption capacities of 0.822 and 0.330 mg/g for treated and untreated TGL, respectively. Statistical analysis (ANOVA) results further identified the most significant factors influencing MB biosorption. These findings highlight the potential of NaOH-treated TGL powder as an effective and eco-friendly solution for removing MB dye from industrial effluents, contributing to sustainable wastewater treatment and environmental protection.

A green strategy to realize the high value utilization of lignin for hydrogel formation

Grafting lignin extracted from pulping black liquor onto hydrogel not only endows hydrogel with strong adsorption capacity, but also realizes the high value utilization of lignin, thereby alleviating the environmental pressure caused by the exhaust gas generated by direct combustion of black liquor. However, those lignin fragments have lost generous active functional groups as the high temperature polycondensation during industrial production, restricting the improvement of lignin-based hydrogel adsorption capacity. Herein, we propose a strategy combining amination and oxidation to prepare lignin derivatives with low molecular weight and high activity groups. The introduced amino groups promote the Cα-Cβ cleavage of β-O-4 unit and the oxidation treatment converts S-unit hydroxyl to carboxyl. The hydrogel obtained by grafting aminated-oxidized-lignin shows satisfactory adsorption performance with a methylene blue adsorption capacity of 697.47 mg/g (vs. 195.12 mg/g for pristine hydrogel). The retention ability has also been greatly improved that only 0.43 % of the adsorbed methylene blue is released even after 96 h (vs. 5 % within just 12 h for pristine hydrogel). This work not only provides a new strategy for the high-value utilization of biomass resources, but also offers a new idea for the preparation of hydrogels with high adsorption performance.

NaOH activated Galla chinensis residue hydrochar for the adsorption of methylene blue

To achieve the resource utilization of waste materials, this study utilized Galla chinensis residue (GCR) as a raw material to synthesize green hydrochar (HC) in one step, activated with NaOH to obtain alkali-activated hydrochar (AHC), which was then used for the adsorption of organic dye methylene blue (MB). The results showed that when the temperature was 25 °C, the pH was 7 and the MB concentration was 300 mg/L, the adsorption capacity (AC) of MB by AHC was 278.97 mg/g and the removal rate was 78.67 %. Langmuir (R2 = 0.9949) and the pseudo-second-order dynamics model (R2 = 0.9983) described the adsorption behavior of MB on AHC, which was an exothermic process according to thermodynamics. The adsorption mechanism included electrostatic attraction, hydrogen bond, π-π interaction, and the pore filling effect. Even after 5 cycles of adsorption–desorption, the AHC adsorbent maintained a high AC for MB, indicating that the HC prepared from GCR was a sustainable and promising adsorbent for MB, providing a new application direction for the reuse of GCR.

Anthill clay activated Ocimum gratissimum extract for effective adsorption of methylene blue and chromium (VI) ion from wastewater: Insights into the adsorption isotherms, kinetics, thermodynamics, and mechanisms

The removal of methylene blue (MB) dye and hexavalent chromium (Cr(Vl)) ions from water bodies have necessitated the search for a promising adsorbent material with high adsorptive performance, facile operation, and economical. Here, a novel adsorbent was prepared by activating anthill clay (AC) with Ocimum gratissimum leaf extract (OG@AC) by ultrasonic strategy method to eliminate MB and Cr(Vl) from the aqueous environment; however, the activation strategy serves as an important factor that influenced the adsorptive performance towards MB and Cr(Vl). Furthermore, a high BET surface area of 120.48 m2/g was measured for OG@AC which is attributed majorly to the green activation strategy. The SEM micrograph of OG@AC was seen to have displayed a leaf-like plate formed by quartz and kaolin. In the batch experimental study, the MB and Cr(Vl) adsorption capacities towards OG@AC were determined to be 227.52 and 143.45 mg/g, respectively. Also, the adsorption kinetics and isotherms models results revealed that the adsorption process of OG@AC towards MB and Cr(Vl) was best described by pseudo-first-order and Freundlich models, suggesting that the adsorption process involves a multilayer physisorption. Moreso, thermodynamic results revealed the adsorption process is feasible, spontaneous, and endothermic in nature. The OG@AC exhibited an outstanding regeneration ability and stability towards MB and Cr(Vl) by maintaining a removal efficiency of 79.11 % and 81.20 % even at the tenth successive adsorption-desorption cycles. Overall, this research sheds more insight on how anthill clay is activated using a feasible design and green chemical (Ocimum gratissimum leaf extract) to enhance its adsorptive performance towards MB and Cr(Vl), which can broaden its wide application in the real world.

Chitosan‐Carbon Aerogel for Efficient Removal of Methylene Blue Dye: Synthesis, Characterization, Adsorption Mechanism and Antimicrobial Therapies

AbstractChitosan‐carbon aerogel was synthesized via a facile and eco‐friendly method and characterized for its structural and morphological properties. The composite exhibits remarkable adsorption kinetics and a high potential for removing Methylene Blue (MB) dye, attributed to its enhanced surface area, porous structure, and active functional groups. The adsorption capacity of chitosan‐carbon aerogel increased from 38 to 86.8 mg/g as the pH was raised from 2 to 7. The maximum MB adsorption capacity increased from 22 to 632 mg/g as the initial MB concentration increased from 25 to 2000 mg/L. The saturation adsorption capacity of the chitosan‐carbon aerogel was 668 mg/g. After five reuse cycles, the removal efficiency dropped from 89 % to 73.1 %. Antibacterial tests showed that the width of the inhibition zone for S. enterica was 16.2 ± 0.38 mm, indicating similar antibacterial activity for both chitosan and chitosan‐carbon aerogels. These findings underscore the potential of chitosan‐carbon aerogel as a sustainable and cost‐effective solution for dye removal in wastewater treatment.

Synergy of Magnetic Nanoparticles and Sodium Alginate-Coated Lignin for Effective Pollutant Remediation, Simple Recovery, and Cost-Effective Regeneration.

In the pursuit of sustainable materials for environmental remediation, this study presents the development and comprehensive characterization of cobalt ferrite nanoparticles (CFNPs) incorporated in lignocellulosic-derived sodium alginate (CFNPs@LCG-SA) biocomposite beads. These biobased beads exhibit exceptional adsorption capabilities, particularly for methylene blue (MB) dyes, rendering them promising candidates for wastewater treatment. Using a comprehensive range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis-derivative thermogravimetry (TGA/DTG), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), etc., we elucidated their structural, physicochemical, and thermal properties. Their multifunctional nature, derived from lignin and sodium alginate components, provides ample active sites for both physical interactions and chemical bonding with contaminants apart from the magnetic character attributed by the CFNPs. With a freeze-drying approach, the optimal adsorption capacity and removal rate of MB reached 97 mg/g and 99%, respectively, and no meaningful decline in their activity was noted even after six cycles. The CFNPs@LCG-SA biocomposite beads emerge as a cost-efficient and sustainable remedy for environmental cleanup, offering valuable perspectives in environmental preservation and advancing green energy technologies.

Ternary‐Grafted Starch‐Based Hydrogel with Improved Adsorption Capacity for Dyes

AbstractBiomass‐based hydrogels can be used as the adsorbents in sewage water, as they have good adsorption capacity for heavy ions and dyes. A ternary‐grafted starch‐based hydrogel, St1.0/CMC0.5/P(AM3.0‐AA5.0‐AMPS1.0), was prepared using cornstarch (St) and sodium carboxymethyl cellulose (CMC) as raw materials, with acrylamide (AM), acrylic acid (AA), and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) as graft monomers. Due to the introduction of CMC and AMPS, the number and type of effective adsorption functional groups in the St1.0/CMC0.5/P(AM3.0‐AA5.0‐AMPS1.0) hydrogel increased, leading to an improved adsorption capacity and removal rate for methylene blue (MB). The maximum adsorption capacity and removal rate for MB could be 1624.49 mg/g and 91.8 %, respectively, at 25 °C. According to the adsorption isotherm and adsorption kinetics, the MB adsorption process on the hydrogel occurs according to the Langmuir isotherm model and quasi‐second‐order kinetics via a chemisorption process occurring on the adsorbent monolayer. Moreover, the St1.0/CMC0.5/P(AM3.0‐AA5.0‐AMPS1.0) hydrogel displayed good regeneration performance. The removal rate for MB could still achieve 84.3 % after the hydrogel was reused four times.

Application of sewage sludge derived hydrochar as an adsorbent for removal of methylene blue

Hydrothermal pretreatment (HTP) is used to convert biomass into hydrochar (HC) through the application of heat and pressure in a water-based medium. The HC has emerged as a promising material for various environmental applications including wastewater treatment, soil amendment, and carbon sequestration. In this study, the applicability of sewage sludge (SS) derived HC was tested as an adsorbent for methylene blue (MB) dye removal from wastewater. The HC was also subjected to chemical activation with KOH before the adsorption study. The HC samples were characterized for structural morphology and molecular functionalities using instrumental analysis. All the HC samples exhibited almost similar adsorption capacity (∼190 mg/g) for MB after 24 h of contact time (MB concentration = 200 mg/L, solution pH = 7 and adsorbent dose = 1 g/L). The equilibrium data could be adequately fit in Langmuir model equation. The negative value of free energy indicated favorable MB adsorption process. The study demonstrated that the SS derived HC can be recycled as adsorbent in wastewater treatment plant which is not only an environment-friendly approach but also may reduce cost of tertiary treatment at sewage treatment plant often required to remove emerging contaminants.

Alginate/organo-selenium composite hydrogel beads: Dye adsorption and bacterial deactivation

Post-COVID-19, the risk and spread of germs, coupled with wastewater contamination, have become critical concerns. Wastewater contains waterborne bacteria and various contaminants like dye molecules, threatening water safety. Traditional adsorption methods address pollutant removal or pathogen inactivation separately, but a dual-action solution is increasingly essential. This study presents alginate/selenium composite hydrogel beads with the potential to simultaneously remove dyes and deactivating bacteria. Fabricated by dropping suspension droplets into a calcium ion bath, these beads were tested for dye adsorption and antibacterial efficacy. Beads with 50 wt% organo‑selenium demonstrated the highest methylene blue (MB) adsorption capacity and nearly 100 % deactivation efficiency against Pseudomonas aeruginosa, while those with 20 wt% showed no significant improvement. Mechanistic studies reveal that organo‑selenium induces stacking effects and reduces surface charges, enhancing MB adsorption and antibacterial performance. The alginate/organo‑selenium composite hydrogel beads offer a potential effective and sustainable solution for tackling the complex issue of wastewater pollutants.

Performance of Bioenergy Production from Durian Shell Wastes Coupled with Dye Wastewater Treatment

Adsorption using biochar is a high-efficient method for removing dyes from wastewater, and it has become a hot research topic in recent years. Biochar produced from organic wastes through pyrolysis is a promising way to combine bioenergy recovery and dye removal. In this study, durian shell (DS) was used as a feedstock for biochar and bio-oil production under different pyrolysis temperatures (400, 500, and 600 °C) for bioenergy recovery. Then, the biochar was applied as the absorbent for methylene blue (MB) removal from wastewater under batch and continuous experiments. It was found that the bio-oil production was slightly affected by temperature, while the productivity of biochar decreased from 42.05% to 30.65% with the increase in pyrolysis temperature from 400 to 600 °C. Compared with the biochar produced at 500 °C (DS-500) and 600 °C (DS-600), the biochar obtained at 400 °C (DS-400) exhibited higher MB removal efficiency and adsorption capacity under various pH conditions due to the superior microstructure. A high pH condition was beneficial for the adsorption process with DS-400. Additionally, the MB removal efficiencies increased with the increase in biochar dosage by providing more activated sites. A high MB content can promote the adsorption process, but a too high MB content negatively affects the removal efficiency due to the sorption saturation. Adsorption processes are more likely to match a pseudo-second-order model by chemical reactions. In the long-term continuous experiment, MB can be effectively removed to match the discharge standard by DS-400. This study provided a sustainable pathway for organic waste disposal and dye wastewater treatment.

Investigation on novel chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) and its potential application for organic dyes removal from aqueous solution

Chitosan, a natural polysaccharide, has attracted considerable attention as an environmentally friendly and highly efficient adsorbent for dye removal. It is usually produced by deacetylation or partial deacetylation of chitin. However, conventional sources of chitin and chitosan are limited, prompting the need for alternative sources with improved adsorption capabilities. Herein, this study focuses on exploring a novel chitin and chitosan source derived from the dung beetle and evaluates its potential for organic dye removal from aqueous solutions. The research involves the extraction and characterization of chitin and chitosan from dung beetle Heteronitis castelnaui (Harold, 1865) using various analytical techniques, including SEM, FT-IR, TGA, XRD, NMR, deacetylation degree and elemental analysis. The chitosan obtained was used for the formation of hydrogels with sodium alginate via cross-linking with calcium chloride. And then the prepared hydrogels were evaluated for its adsorption capacity through batch adsorption experiments using methylene blue as a model pollutant. The adsorption capacity for methylene blue was 1294.3 mg/g at room temperature with solution pH = 12, MB concentration of 1800 mg/L. Furthermore, the kinetics of the adsorption process were analyzed using pseudo-first-order and pseudo-second-order models to understand the rate of adsorption. The maximum adsorption capacities were determined using Langmuir and Freundlich isotherm models. This study provides valuable insights for the development of sustainable dye adsorption technologies, specifically investigating a novel chitosan source derived from the dung beetle.

Methylene blue sorption performance of lignocellulosic peach kernel shells modified with cellulose derivative chitosan as a new bioadsorbent

In this study, adsorption isotherms (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) and thermodynamic properties of cationic methylene blue (MB) dye adsorption onto chitosan-coated peach kernel shell waste (CTS-PKSh) from wastewater were investigated. CTS was cross-linked with citric acid (CA) and glutaraldehyde (GA). The adsorbents were characterized by FE-SEM/EDS, FTIR, and particle size distribution. MB adsorption behavior onto the biosorbents was investigated concerning parameters such as adsorbent dosage (0.8–8 g/L), time (0–540 min), pH (3−10), initial dye concentration (50–700 mg/L), and temperature (25–55 °C). The Langmiur qmax and experimentally qe MB adsorption capacities of the new adsorbents were found to be 227.27 and 201 mg/g for CA cross-linked CTS-PKSh (CA@CTS-PKSh) and 111.12 and 96.5 mg/g for GA cross-linked CTS-PKSh (GA@CTS-PKSh), respectively. The results of thermodynamic analysis showed that adsorption was feasible, exothermic, and spontaneous. According to adsorption and recyclability results, CA@CTS-PKSh was more effective for MB removal at a 2 g/L adsorbent dose for an initial dye concentration of 100 mg/L, 25 ± 1 °C, contact time 60 min, and pH 7.

Preparation of Co x Mg y Cu(1- x - y )Fe2O4 nanoparticles and their adsorption mechanism of methyl blue

A facile rapid-combustion process was introduced for preparing magnetic Co x Mg y Cu(1- x - y )Fe2O4 nanoparticles, and to enhance their specific surface area and saturation magnetization, the optimization involved adjusting the element proportion, calcination temperature, and solvent amount. The optimal element proportion of x:y:(1-x-y) for Co x Mg y Cu(1- x - y )Fe2O4 nanoparticles was 0.1:0.7:0.2, and the effects of solvent amount, and calcination temperature were also investigated. The average particle size and specific surface area of Co0.1Mg0.7Cu0.2Fe2O4 nanoparticles calcined at 400 °C with 25 mL absolute alcohol were 17.9 nm and 56.96 m2/g, respectively; while demonstrating a saturation magnetization of 8.5 emu/g. To solve the increasingly severe issue of water pollution, these nanoparticles were employed to efficiently treat dye wastewater containing methyl blue (MB). After fitting kinetic and isotherm models, the adsorption process of magnetic Co0.1Mg0.7Cu0.2Fe2O4 nanoparticles for MB dominated by chemisorption and was a multilayer adsorption process. The adsorption isotherm experiments revealed a remarkable maximum adsorption capacity of methyl blue, reaching 2255.7 mg/g, within the concentration range of MB from 400 to 4000 mg/L. The thermodynamic analysis indicated the spontaneity of the exothermic adsorption process. The studies on the effect of pH also led to satisfying results; while the residual adsorption capacity could still remain 91.2% initial adsorbance after 12 times recycle. The outstanding recycling ability, resistance to ionic strength, and pH resistance distinguished the magnetic Co0.1Mg0.7Cu0.2Fe2O4 nanoparticles among vast adsorbents. These results highlight the significant potential of these nanoparticles for treating dye wastewater.

Effectiveness of Porous Durian Shell-based Activated Carbon for Methylene Blue Adsorption

In this study, durian shell-based activated carbon (DAC) was produced via chemical activation method by utilising durian shell and sulphuric acid (H2SO4) as the starting material and activating agent, respectively. The incorporation of H2SO4 in the DAC production process resulted an improvement in the surface properties and adsorption capacity of the produced DAC adsorbent. Field emission scanning electron microscopy analysis further showed that the produced DAC possessed a porous structure which was beneficial for dye adsorption application. Under operating conditions of 500°C and 3 hours carbonisation temperature and time, the Brunauer–Emmett–Teller (BET) surface area, total pore volume and BET average pore diameter were measured to be 242.03 m2/g, 0.028 cm3/g and 2.28 nm, respectively. The adsorption performance of the produced DAC was then investigated using methylene blue (MB) as the model adsorbate. The optimum MB dye removal and adsorption capacity were found to be 92.05% and 0.767 mg/g, respectively, with 0.6 g of DAC dosage, 10 ppm of initial MB dye concentration and 15 min of contact time.