Adsorption Of MB Research Articles

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.

Ag2O/ZnO/CuO and Ag2O/ZnO/NiO immobilised on reduced graphene oxide: synthesis, characteristics and its adsorption, catalytic behaviour and antibacterial activities

ABSTRACT Ag2O/ZnO/CuO (A/Z/C) and Ag2O/ZnO/NiO (A/Z/N) nanometal oxides were synthesised in different rations by co-precipitation method and were immobilised on reduced graphene oxide (rGO). The prepared nanocomposites were characterised by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Their application in the adsorption of MB, RhB and MO dyes, olefin oxidation and antibacterial properties were investigated. The results showed that A/Z/N/rGO adsorbent has 99% (10 min), 93% (20 min) and 97% (12 min) adsorption of MB, RhB and MO, respectively. From the investigation of Freundlich and Langmuir models, it was found that the adsorbent follows Langmuir. Moreover, the reaction thermodynamics was also studied, the reaction was endothermic and spontaneous. The kinetics of dye adsorption MB, RhB and MO on the surface follow a pseudo-second order model. At optimum condition, the conversion and selectivity of α-methylstyrene to acetophenone was >99% by A/Z/N and A/Z/C catalysts. A/Z/C/rGO nanocomposite has good antibacterial properties against two bacteria E. coli and S. aureus.

Fabrication of nanozeolite-Y/chitosan composite based on rice husks for efficient adsorption of methylene blue dye: kinetic and thermodynamic studies

In this work, three solid adsorbents were synthesized, namely, nanozeolite-Y prepared from rice husks ash by a sol-gel method as a green biosource (ZN), chitosan as a cationic biopolymer (CS), and nanozeolite-Y/chitosan composite (CSZ). An eco-friendly composite that consists of chitosan and nanozeolite-Y was used to combine the advantages of nanoparticles with biopolymers two materials to increase the removal % of methylene blue dye. All the synthetized solid adsorbents were investigated using TGA, nitrogen adsorption, SEM, TEM, FTIR, XRD, and zeta potential. The results showed that CSZ particles had a high specific surface area (432.3 m2/g), mesoporosity (with an average pore diameter of 2.59 nm), a smaller TEM particle size (between 28.6 and 60.7 nm), a lot of chemical functional groups, and high thermal stability. CSZ exhibited the maximum adsorption capacity (141.04 mg/g) towards methylene blue. The adsorption nature of methylene blue onto CS and CSZ is endothermic, spontaneous, and a physical adsorption process, while it is exothermic, nonspontaneous, physical adsorption process in the case of ZN, as confirmed by thermodynamic results. Pseudo-second order, Elovich, Dubinin-Radushkevich, Freundlich, Langmuir, Temkin, and adsorption models all fit the MB adsorption well, with correlation coefficients reaching about 0.9997. Nitric acid was found to be the best desorbing agent, with a desorption efficiency of about 99%.

Enhancing hydrochar production and proprieties from biogenic waste: Merging response surface methodology and machine learning for organic pollutant remediation

The valorization of biogenic waste by hydrothermal carbonization is widely discussed in research. However, to our knowledge, no study has combined almond shells and olive pomace to synthesize a solid carbon material. The purpose of this study is to enhance the hydrochar process from AS and OP using RSM methodology and machine learning models: ANN, SVM and XG-Boost. Subsequently, a study was carried out on the removal of organic pollutants by the synthesized material. The optimum Co-HTC operating conditions obtained at 180 C, 90 min with acid catalyst corresponding to 71.51 % and 87.13 % for mass yield and carbon retention rate respectively according to RSM-CCD. The comparison between RSM-CCD and ML in terms of prediction concludes that RSM remains more efficient in terms of planning and optimization. However, ANN is more suitable for modeling and predicting mass yields and carbon retention rates. Hydrochar’s physicochemical properties were evaluated by the use of spectroscopic methods like FTIR, SEM, XRD, and CHNO. To conclude, we studied the performance of HCop in methylene blue adsorption, varying the following parameters: pH, contact time, initial dye concentration, adsorbent dose and temperature. In addition, kinetic and isothermal models were studied to describe the dominant mechanisms in the MB adsorption process. The MB maximal adsorption using HCop obtained at pH 9, with an initial dye concentration of 100 mg. L−1, 40-min contact time, 0.1 g/L adsorbent dose, and a temperature between 25 and 30 °C. In conclusion, these results provide important information on the use of Co-HTC to convert biogenic wastes into high-performance carbon materials for the appropriate removal of organic pollutants. More studies are needed to use the material in other fields of application.

Preparation of Au Nanoparticle Loaded Biochar/Polydopamine Composites for Adsorption of MB and MG Dyes from Aqueous Solution

Preparation of Au Nanoparticle Loaded Biochar/Polydopamine Composites for Adsorption of MB and MG Dyes from Aqueous Solution

Adsorption of cationic dye onto Raphanus seeds: optimization, adsorption kinetics, thermodynamic studies

Dyes are one of the common contaminants in industrial wastewater. Adsorption is the most widely method which used to treat dye-contaminated water due to their easy use, cost-effectiveness, and their efficiency was high. The aim of this study is the investigating of the utilization of the activated carbon which prepared from Raphanus seeds solid residual (ACRS) as a low cost adsorbent for removing of cationic Methylene Blue dye (MB)from wastewater. measuring the surface area using BET methods and SEM. The FT‒IR and XRD was measured. Different variables (e.g.: initial concentration of the dye, pH, contact time, and dosage) have been studied. Process has been systematically investigated experimentally at (25 ± 1 °C). The % removal of MB reached 99.4% after 90-min MB adsorption (40 mg/L) was observed within 5 min of contact time for the Raphanus seeds solid residual (ACRS) dosage of 4 g/L. MB initial concentration (10 ppm) Raphanus seeds solid residual (ACRS) effectively adsorbed MB (> 99%) over a widely range of pH (from pH 2 to pH 8). However, a swift decline in removal was observed when the pH was set at 7. The results of the adsorption kinetics analysis indicate a strong correlation with the pseudo-second-order model, as evidenced by the high regression coefficients. However, the adsorption capacity diminished with a rise in temperature. Thermodynamic calculations of (MB) onto Raphanus seeds solid residual (ACRS) is an exothermic reaction. The results have been indicated that the effectiveness of MB removal by activated carbon prepared from Raphanus seeds solid residual is favorable under neutral conditions, Raphanus seeds solid residual (ACRS) can be considered an efficient, environmentally friendly, readily available, and economical adsorbent that could treat industrial wastewater contaminated with cationic textile dyes. The objective of the experiments was to investigate the impact of various factors on the response of a process or formulation. To accomplish this goal, response surface methodology (RSM) has employed as a statistical model. RSM is an efficient and effective method for optimizing processes through the use of a quadratic polynomial model. The utilization of RSM allows for a reduction in the number of experiments needed, thus minimizing the associated costs of extensive analysis. This method has been done using Box–Behnken Design (BBD) to optimize % removal of MB. The optimal conditions as obtained from the RSM is pH 7,contact time 120 min, initial concentration 10 ppm, ACRS dosage 1 g, adsorption temperature 45 °C.

Ultrasound and enzyme treatments on morphology, structures, and adsorption properties of cassava starch

Porous starch materials are environmentally friendly and renewable and exhibit high adsorption performances. Ultrasound and compound enzyme (α-amylase and glucoamylase) treatments were applied to prepare modified cassava starch. The granules, crystal morphology, crystal structure, and molecular structure of starch were investigated. The hydrolysis degree, solubility, swelling, and adsorption properties of cassava starch were analyzed. After the cassava starch was modified by ultrasound and enzyme treatments, the granule size of the starch decreased, and the surfaces were eroded to form pits, grooves and cavity structure. The starch spherulites weakened or even disappeared. The functional groups of starch did not change significantly, but the degree of crystal order decreased. The double-helix structure was reduced, and the crystal structure was composed of A + V-type crystals, with a decrease in crystallinity. The gelatinization temperature and thermal degradation temperatures enhanced. The enzymatic hydrolysis degree and solubility of the modified cassava starch increased. The swelling degree decreased, and oil adsorption, water adsorption improved. MB adsorption behavior of modified cassava starch closely followed a pseudo-second-order kinetics model and the Langmuir isotherm equation. These findings could help to understand the relationship between the structure and properties of modified starch, and guide its application in the field of adsorption.

Efficient removal of Methylene blue dye from aqueous medium utilizing eco-friendly chitosan adsorbents

ABSTARCT Dyes released through various industrial operations are a major threat to the environment. The recent study introduced an eco-friendly adsorbent based on the grafting of phenolic acids (caffeic and/or gallic acids) on chitosan to reduce the hazardous impact of color effluent pollution. The morphology and structure of synthesized adsorbents were confirmed by physical and chemical tools such as TGA, FTIR, SEM, EDX, point of zero charge, water regain, and resistance of adsorbents to dissociation in acidic media. The synthesized adsorbents’ removal efficiency toward MB dye, a model cationic organic pollutant, from aqueous medium was evaluated. The factors impacting dye adsorption were investigated, including pH, dye initial concentration, and temperature. The response surface methodology (RSM) was used to confirm the interaction effects of the process variables and optimize the ideal conditions of adsorption. The maximum adsorption capacity was 257.0 and 391.8 mg/g for AI and AII, respectively, at initial MB concentration of 550 ± 1 mg/L, pH 8, and 21 ± 1 °C. MB adsorption is an exothermic chemosorption process that takes place via electrostatic attraction in an alkaline medium. Both AI and AII demonstrated significant reuse ability when eluted with a 0.5 M HCl solution.

Enhanced removal of methylene blue and procion deep red H-EXL dyes from aqueous environments by modified-bentonite: Isotherm, kinetic, and thermodynamic

This study aims to enhance local bentonite's effectiveness in removing methylene blue and procion deep red dyes from aqueous media through organic modification with cetyltrimethylammonium bromide surfactant. Raw and modified bentonites were analyzed using XRF, XRD, FTIR, BET/BJH, and DSC techniques. The modified bentonite showed a crystalline structure and mesoporous morphology with a heterogeneous surface. Optimal adsorption conditions for MB dye were 0.2 g adsorbent dose, 60 min contact time, 60 mg/L initial concentration, and pH 8, achieving a maximum sorption capacity of 6.418 mg/g. For PDR dye, optimal conditions were a 0.125 g adsorbent dose, 40 mg/L initial concentration, 30 min contact time, and acidic pH, with a maximum adsorption capacity of 8.503 mg/g. Isotherm analysis indicated the Langmuir model best fits the adsorption data, suggesting a mono-layer adsorption process. Kinetic investigations revealed that the adsorption follows a pseudo-second-order model, indicating a chemisorption mechanism. Thermodynamic results showed exothermic adsorption for MB and endothermic adsorption for PDR. This work highlights the potential of surfactant-modified bentonite as a cost-effective sorbent for treating polluted aqueous systems, effectively removing both cationic and anionic dyes.

Efficient construction of low shrinkage xerogels via coordination-catalyzed in-situ polymerization for activated carbon xerogels with multi-dyes adsorption

Obtaining large specific surface areas (SSA) for carbon xerogels poses a significant challenge due to the inevitable volume shrinkage of xerogel. Here, the Zn2+ coordination-catalyzed in-situ polymerization approach was proposed to fabricate xerogels with a low shrinkage of 13.03 % and a short preparation period of 24 ​h. In resorcinol-formaldehyde (RF) polymerization, ZnCl2 could accelerate the reaction kinetics through the coordination of the Zn2+ and hydroxyl groups. The gel network with adjustable RF particles (46.5 nm-1.89 ​μm) and narrow neck structures was constructed by changing ZnCl2 and ethanol contents, which could resist volume shrinkage during atmospheric drying without solvent exchange. The activated carbon xerogels (ACXs) with hierarchical structure were designed by one-step carbonization/activation due to the pore-forming of ZnCl2. The obtained ACXs showed a large SSA of 1689 ​m2/g, multi-dyes adsorption capacity (methylene blue, Congo red, methyl orange, and Sudan III were 625.90, 359.46, 320.69, and 453.92 ​mg/g, respectively), and reusability of 100 %. The maximum monolayer MB adsorption capacity was 630.28 ​mg/g. This work presents an efficient strategy to design porous nanomaterials with low shrinkage and large SSA, which illustrates promising applications in separation, adsorption, and photoelectric catalysis.

Assessment of Removal Methylene Blue and Green Dye in Water by Adsorption in Aqueous Solution by the Pan Bottom from a Mining Waste from Betaré-Oya

This work focuses on the study of the adsorption of methylene blue (BM) and a green dye (CV) in aqueous solution by the pan bottom from a mining waste from Betaré-Oya. The aim is to recover mining waste as an adsorbent. The influence of physico-chemical parameters on the kinetics and isotherm of adsorption of these dyes on the pan bottom was determined. The UV/Visible spectroscopy technique was used for the analyses. The green dye was study at spectral wavelength 570 nm. Green. Adsorption equilibrium times are 15 minutes for these dyes. Experiments show that when the bottom mass of the pan increases, the quantities adsorbed decrease. In fact, it is the adsorption yields that increase from 60 to 80% for BM and from 30 to more than 90% for CV. Variations in pH showed greater adsorption of dyes in basic medium (pH ≥ 10) which indicates that the dyes are cationic. It was also observed that the amounts of BM and CV per unit of pan bottom increase with increasing initial concentration. The experimental data was analyzed by isotherm models. The value of the constant n of the Freundlich model for BM is 1.53, indicating that adsorption is unfavorable, whereas in the case of CV, adsorption is moderate. Langmuir and Temkin models better describe MB adsorption. The mechanism of adsorption of BM and CV is of chemical type. Pseudo-first-order, pseudo-second-order, Elovich and intra-particle kinetic models have been applied on data and the most suitable is the pseudo-second-order kinetic model.

Surface Modifications of Superparamagnetic Iron Oxide Nanoparticles with Chitosan, Polyethylene Glycol, Polyvinyl Alcohol, and Polyvinylpyrrolidone as Methylene Blue Adsorbent Beads.

Due to the negative impacts the dye may have on aquatic habitats and human health, it is often found in industrial effluent and poses a threat to public health. Hence, to solve this problem, this study developed magnetic adsorbents that can remove synthetic dyes like methylene blue. The adsorbent, in the form of beads, consists of a polymer blend of chitosan, polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and superparamagnetic iron oxide nanoparticles (average size of 19.03 ± 4.25 nm). The adsorption and desorption of MB from beads were carried out at pH values of 7 and 3.85, respectively. At a concentration of 9 mg/L, the loading capacity and the loading amount of MB after 5 days peaked at 29.75 ± 1.53% and 297.48 ± 15.34 mg/g, respectively. Meanwhile, the entrapment efficiency of MB reached 29.42 ± 2.19% at a concentration of 8 mg/L. The cumulative desorption capacity of the adsorbent after 13 days was at its maximum at 7.72 ± 0.5%. The adsorption and desorption kinetics were evaluated.

Unveiling the Nature of lignin's Interaction with Molecules: A Mechanistic Understanding of Adsorption of Methylene Blue Dye.

The valorization of lignin into advanced materials for water and soil remediation is experiencing a surge in demand. However, it is imperative that material research and manufacturing be sustainable to prevent exacerbating environmental issues. Meeting these requirements necessitates a deeper understanding of the role of lignin's functional groups in attracting targeted species. This research delves into the interaction mechanisms between lignin and organic molecules, using the adsorption of the cationic dye Methylene Blue (MB+) as a case study. Herein, we aim to quantitatively estimate the contribution of different interaction types to the overall adsorption process. While carbonyl groups were found to have no significant role in attraction, carboxylic groups (-COOH) exhibited significantly lower adsorption compared with hydroxyl groups (-OH). Through alternately blocking aliphatic and phenolic -OH groups, we determined that 61% of the adsorption occurred through hydrogen bonding and 38% via electrostatic interactions. Performance studies of modified lignin along with spectroscopic methods (XPS, FTIR) confirmed the negligible role of π-π interactions in adsorption. This study offers fundamental insights into the mechanistic aspects of MB adsorption on lignin, laying the groundwork for potential modifications to enhance the performance of lignin-based adsorbents. The findings underscore the importance of hydroxyl groups and provide a roadmap for future studies examining the influence of steric factors and interactions with other organic molecules.

Fabrication of used-tea embedded alginate beads for cationic dye remediation: Synergistic effect of surface adsorption and intraparticle diffusion

Water pollution has become a major concern due to high industrialization and poor waste management policies. Recently, organic contaminants such as dyes are severely influencing environmental conditions and therefore, it must be employed to efficient treatment processes before discarding in waterbodies. In this work, used-tea embedded alginate beads were fabricated as a novel adsorbent for removing a cationic dye (methylene blue, MB). The physical properties of fabricated beads were investigated and also characterized using field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The highest MB removal efficiency of about 97.38 ± 1.84% was obtained at optimized pH 7 and 25 °C. The adsorption capacity (qe) increased with MB concentration and the pseudo-second-order model exhibited excellent fit. MB adsorption comprises rapid surface adsorption (initial 5 min) and slow inter-particle diffusion (after 5 min). Supporting the Langmuir isotherm indicated the formation of a monolayer of MB on the surface of the beads and the calculated maximum adsorption capacity (qm) was 421.94 mg/g. Negative ΔG (-7.25 kJ/mol) and ΔH (-52.67 kJ/mol) reveal MB removal as a spontaneous and exothermic process. Positive entropy change of ΔS (152.05 J/mol) states increased randomness, facilitating promoted affinity of beads for free MB molecules. A removal efficiency of about 90.40 ± 2.91% was obtained up to 3rd cycle of its reuse, which further decreased to 67.11 ± 1.72% during 5th cycle. The MB adsorption mechanism was investigated by comparing the physiochemical and morphological characteristics of beads before and after MB removal.

Preparation of highly microporous activated carbon by utilizing inherent iron in coal through CO2 and steam co-activation for improving CO2 capture and methylene blue removal

Pore-tailoring by utilizing the inherent iron mineral in coal for highly microporous activated carbon (AC) preparation for boosting adsorption ability is a promising strategy. In this work, AC-XFeS2 (X indicates the contents of pyrite in coal, 0–3 wt.%) was prepared via blending demineralized Taixi coal and pyrite and followed by CO2 and steam co-activation. The iron minerals transformation, AC physicochemical textural development and performance were investigated by various analyses. The results indicate that: (1) Pyrite (FeS2) can transform into magnetite (Fe3O4) and hematite (Fe2O3) during CO2 and steam co-activation. Pyrite declines the graphitization degree and enhances the increment of AC’s C=O, COO, and π–π* content. Pyrite favors the increase of AC’s micropore porosity. High SBET and Smic of 1587 m2/g and 949 m2/g of AC-1FeS2 were achieved, which is higher by 13.5% and 83.6% than AC of 1398 m2/g and 517 m2/g, respectively. (2) The CO2 adsorption capacity of AC-1FeS2 is up to 2.06 mmol/g at 25 °C and 1.0 bar, which is higher by 11.3% than 1.85 mmol/g of AC. The enhancement of micropore by pyrite is the main aspect of improving CO2 capture. (3) AC-1FeS2 presents maximum MB adsorption capacity, reaching 63.3 mg/g, which is higher by 19.3% than 53.3 mg/g of AC. A serious of kinetics models was studied and the MB adsorption process could be better reflected by Pseudo second-order kinetics (R2=0.9538). The enhanced pore-filling, π–π* stacking and C=O complexation are one aspect of improving MB removal. In addition, the effect of Fe-O bonds or magnetic particles including Fe3O4 also enhances MB removal. The results of this investigation could provide new avenues and theoretical support for cost-effective AC with highly microporous production by utilizing high-iron-sulfur coal, to some extent, guide the actual industrial application.

Enhancing the adsorption capacity of organic and inorganic pollutants onto impregnated olive stone derived activated carbon

This study presents a sustainable approach to activated carbon production from olive stones in comparison to commercial ones, using various activating agents such as H3PO4, KOH, and ZnCl2, for enhancing the adsorption properties and versatile adsorption capability to remove a range of pollutants including copper ion, methylene blue, and 2,4-Dichlorophenoxyacetic acid from aqueous solutions. The performances of activated carbons across varying conditions such as pollutant concentrations, temperatures, pH levels, and adsorbent amounts were tested. Increased initial pollutant concentrations correlated with higher adsorption capacities. Maximum adsorption capacities were achieved at pH levels of 5, 10, and 2 for Cu, MB, and 2,4-D, respectively. For KOSAC, Cu removal rose from 27 % to 52 %, for ZOSAC, MB removal increased from 39 % to 65 %, and for ZOSAC, 2,4-D removal surged from 33 % to 99 % at varying adsorbent amounts. Model validation was carried out utilizing the kinetic models (PFO, PSO) and isotherm models (Langmuir, Redlich-Peterson). The PFO kinetic model and Langmuir isotherm model proved more suitability for Cu adsorption, whereas PFO and PSO kinetic models, along with Redlich-Peterson isotherm models, were more prominent for MB and 2,4-D adsorption. Thermodynamic analysis revealed that the adsorption of Cu and 2,4-D was exothermic, while MB adsorption was endothermic. By optimization of experimental conditions, the maximum adsorption capacities were attained at 30.34 °C and 297.65 mg L−1 for KOSAC-Cu, 48.62 °C and 269.37 mg L−1 for ZOSAC-MB, and 30.31 °C and 299.02 mg L−1 for ZOSAC-2,4-D sorption. This research highlights ZOSAC's potential as a cost-effective, eco-friendly solution for water treatment, contributing to environmental sustainability and economical feasibility.

Activated Carbon from Paper Waste as Potential Adsorbents for Methylene Blue and Hexavalent Chromium

Environmental pollution is a significant problem and is increasing gradually as more and more harmful pollutants are being released into water bodies and the environment. Water pollutants are dangerous and pose a threat to all living organisms and the ecosystem. Paper waste is one of the most widespread and largest wastes in the world. This research aims to address two important problems simultaneously: the reduction in solid waste in the environment using activated carbon from paper waste as potential adsorbents and the removal of harmful contaminants from water. Carbon from paper waste was activated with H2O2, HNO3, and KMnO4 for the adsorption of Cr(VI) and MB. SEM, EDX, FTIR, Raman, and BET were used to determine the properties of the materials. The surface morphology of the materials consisted of amorphous particles. EDX shows that all activated samples have a higher content of (O) than carbon paper waste. Adsorption studies showed that there was a stronger interaction between the pollutants and the adsorbent at a higher initial concentration (200 mg/L) than at the lower initial concentrations. The contact time data show that uptake increases when the interaction time between the contaminant and the adsorbent is increased. The tests for the pH of the solution show that the adsorption of Cr(VI) decreases when the pH is gradually increased, whereas the adsorption of MB increases when the pH of the solution is increased. The results fit better with the Freundlich isotherm and PSO models. The temperature studies show that the enthalpy was positive, indicating that the uptake process is endothermic. The Gibbs free energy values were all negative, indicating that adsorption between the adsorbents and the pollutants was favored. After four consecutive cycles, all the samples retained more than 60% of their uptake capability.

Adsorption characteristics of coal gasification fine slag with alkali-dissolution and hydrothermal treatment on methylene blue

ABSTRACT The resource utilization of coal gasification fine slag (FS) and the harmless treatment of dyeing wastewater are crucial for establishing a zero-emission industrial system and a circular economy. This study used FS as raw material and divided it into two particle sizes through ultrasonic pretreatment enhanced wet sieving. The composite materials were synthesized via an alkaline hydrothermal process from different components in FS was compared, and applied as adsorbents for the removal of methylene blue from printing and dyeing wastewater. Finally, the kinetic and thermodynamic model developed for MB from printing and dyeing wastewater. The maximum adsorption of MB by the composite material prepared from low carbon component (<0.125 mm) could reach more than 180 mg·g−1. The research results have important theoretical and practical value for guiding the high-value utilization of FS and its application in dye wastewater treatment.

Adsorption behavior of MB dye on alginate-sepiolite biocomposite beads: Adsorption, kinetics, and modeling

This work is based on the preparation of biocomposite beads Alginate-Sepiolite using a simple preparation method. A series of materials was prepared by varying only the mass of the sepiolite in the biocomposite beads (mass of the sepiolite is varied between 0.5–1.5 g in the reaction mixture). The obtained biocomposites were characterized by XRD, FTIR, TGA, XRF, SEM, and EDX and then tested as adsorbents for the removal of Methylene Blue MB dye in an aqueous solution. To study the adsorption behavior of MB dye on biocomposites, several parameters affecting MB adsorption were investigated and discussed. The results obtained showed that the ALG-Sep composite hydrogels were well formed, and their properties were improved depending on the sepiolite content used. The kinetics and modeling results show that the adsorption process follows first-order kinetics, and the Langmuir model. It was found that the adsorption capacity of MB dye increased with the increase of sepiolite in the composite beads, and adsorption was carried out in the following order ALG-Sep(1.5) > ALG-Sep(1) > ALG-Sep(0.5). The maximum absorption capacity of MB dye on ALG-Sep(1.5) was qmax = 55.49 mg.g−1. Among the advantages of this biocomposite is that it is prepared from natural and non-toxic sources, and it is easily separable after adsorption, which makes it an excellent candidate for the elimination of organic pollutants in polluted waters.

Solid phase speciation controls copper mobilisation from marine sediments by methanobactin

Although marine environments represent huge reservoirs of the potent greenhouse gas methane, they currently contribute little to global net methane emissions. Most of the methane is oxidized by methanotrophs, minimizing escape to the atmosphere. Aerobic methanotrophs oxidize methane mostly via the copper (Cu)-bearing enzyme particulate methane monooxygenase (pMMO). Therefore, aerobic methane oxidation depends on sufficient Cu acquisition by methanotrophs. Because they require both oxygen and methane, aerobic methanotrophs reside at oxic-anoxic interfaces, often close to sulphidic zones where Cu bioavailability can be limited by poorly soluble Cu sulphide mineral phases. Under Cu-limiting conditions, certain aerobic methanotrophs exude Cu-binding ligands termed chalkophores, such as methanobactin (mb) exuded by Methylosinus trichosporium OB3b. Our main objective was to establish whether chalkophores can mobilise Cu from Cu sulphide-bearing marine sediments to enhance Cu bioavailability.Through a series of kinetic batch experiments, we investigated Cu mobilisation by mb from a set of well-characterized sulphidic marine sediments differing in sediment properties, including Cu content and phase distribution. Characterization of solid-phase Cu speciation included X-ray absorption spectroscopy and a targeted sequential extraction. Furthermore, in batch experiments, we investigated to what extent adsorption of metal-free mb and Cu-mb complexes to marine sediments constrains Cu mobilisation.Our results are the first to show that both solid phase Cu speciation and chalkophore adsorption can constrain methanotrophic Cu acquisition from marine sediments. Only for certain sediments did mb addition enhance dissolved Cu concentrations. Cu mobilisation by mb was not correlated to the total Cu content of the sediment, but was controlled by solid-phase Cu speciation. Cu was only mobilised from sediments containing a mono-Cu-sulphide (CuSx) phase. We also show that mb adsorption to sediments limits Cu acquisition by mb to less compact (surface) sediments. Therefore, in sulphidic sediments, mb-mediated Cu acquisition is presumably constrained to surface-sediment interfaces containing mono-Cu-sulphide phases.