Dye Adsorption Capacity Research Articles

Adsorptive removal of toxic methylene blue and crystal violet dyes from aqueous solutions using Prunus spinosa: isotherm, kinetic, thermodynamic, and error analysis

Abstract In this study, it was aimed to use Prunus spinosa L. fruit pulp as an adsorbent zero-waste and low-cost for the removal of toxic methylene blue (MB) and crystal violet (CV) dyes from aqueous solutions. The adsorbent was characterized utilizing FTIR-ATR, SEM, and pHpzc tests. The pHpzc value of the adsorbent is 4.96. According to optimization experiments, the optimum adsorbent dosage was determined as 0.05 g/50 mL for MB and CV dyes, the optimum pH values were determined as approximately 7 for MB and CV dyes, and the optimum contact time was determined as 45 min for MB and 30 min for CV dyes. The Langmuir model has been used to calculate the maximum adsorption capacities of MB and CV dyes at a temperature of 298 K. The obtained values are 59.59 mg/g for MB and 53.19 mg/g for CV. The experimental data for Prunus spinosa L. for both dyes exhibited a pseudo-second-order kinetic model. According to error analyses, the reproducibility and applicability of isotherm and kinetic models were investigated. From thermodynamic results, the enthalpy values were calculated as − 42.04 kJ/mol for MB and − 24.08 kJ/mol for CV dyes, which indicates that the process is exothermic. Also, the Gibbs free energies of MB and CV dyes were determined as − 34.20 kJ/mol and − 32.33 kJ/mol at 298 K, which indicates the process is spontaneous. Research and comparisons with other adsorbents have demonstrated that Prunus spinosa L. is a cost-effective and appealing choice for removing MB and CV dyes from water solutions. Graphical Abstract

Machine learning-driven prediction of biochar adsorption capacity for effective removal of Congo red dye

Congo red, a widely utilized dye in the textile industry, presents a significant threat to living organisms due to its carcinogenic properties and non-biodegradable nature. This study proposes a data-driven machine-learning approach to optimize biochar characteristics and environmental conditions to maximize the adsorption capacity of biochar for the removal of Congo red dye. Therefore, six machine learning models were trained and tested on a dataset containing eleven input parameters (related to biochar properties and environmental conditions) and adsorption capacity. The models were evaluated using performance metrics such as R-squared (R2), Mean Squared Error (MSE), and Root Mean Squared Error (RMSE). With the highest R2 (0.9785) and lowest RMSE (0.1357), Random Forest Regression (RF) outperformed other machine learning models. DT and XGB also performed well, achieving slightly lower R2 values of 0.9741 and 0.9577, respectively. The LR model performed the worst, with the lowest R2 (0.4575) and the highest RMSE (0.6821). Moreover, the reliability of these models was validated using a 10-fold cross-validation method. RF once again performed the best with an R2 value of 0.9762. Feature analysis revealed that the initial dye concentration relative to biochar dosage (C0), specific surface area (BET), and pore volume (PV) are the most significant factors affecting the dye adsorption capacity of biochar, while parameters such as carbon content (C), the oxygen and nitrogen to carbon molar ratio [(O + N)/C], and pore diameter (D) had minimal impact. This research demonstrates that machine learning models can accurately predict biochar’s contaminant adsorption capacity, enhancing wastewater treatment and promoting efficient, cost-effective environmental management.Graphical

Facile Preparation of Poly(AA‐co‐NaAMPS) Hydrogels Toward Toxic Dyes and Heavy Metals Removal via Frontal Polymerization

ABSTRACTWastewater treatment contributes to the sustainable utilization of water resources for alleviating water scarcity. The application of polymeric materials as adsorbents for eliminating hazardous substances in water has garnered extensive attention owing to their remarkable adsorption efficiency, stability, and selectivity. Herein, a facile strategy is provided to rapidly synthesize poly(acrylic acid‐co‐sodium 2‐acrylamide‐2‐methylpropanesulfonate) (poly(AA‐co‐NaAMPS)) hydrogels with exceptional adsorptive capacity via frontal polymerization (FP). The FP processes are meticulously examined in terms of initiator dosage and monomer ratio. The as‐prepared hydrogels demonstrate pH‐responsive swelling ability and pH‐dependent adsorption capacity for various dyes and heavy metal ions. Compared with traditional batch polymerization (BP), the hydrogels prepared by FP exhibit superior swelling and adsorption abilities. Additionally, research on the adsorption mechanism for both dyes and heavy metal ions is conducted by fitting the adsorption kinetic data both with Langmuir and Freundlich equations. The maximum adsorption capacity (qm) of hydrogels derived from Langmuir model for dyes of methylene blue (MB) and rhodamine B (RB) is, respectively, 595.3 and 3078.5 mg g−1, while for heavy metal ions of Cr3+ and Cd2+ is, respectively, 1010.8 and 1191.3 mg g−1. This research exploits an alternative approach for the rapid preparation of high‐efficiency hydrogel adsorbents toward wastewater treatment.

Removal of malachite green dye by adsorption onto chitosan‐montmorillonite nanocomposite: Kinetic, thermodynamic and equilibrium studies

AbstractIn this study, the efficiencies of chitosan, montmorillonite, and chitosan/montmorillonite composites in various ratios for the removal of malachite green dye from aqueous solutions were investigated, and their maximum adsorption capacities were compared, and the effects of factors such as composite concentration, pH, contact time, dye concentration, and temperature were examined. Recovery attempts using different chemicals were also performed. Adsorption was analyzed using Langmuir and Freundlich isotherm models, and thermodynamic analyses were conducted. Fourier‐transform infrared (FTIR) and scanning electron microscopy (SEM) analyses were used to investigate surface changes. The highest adsorption capacity was found for the 20% chitosan/montmorillonite composite (400 mg g−1). Temperature studies indicated a decrease in adsorption capacity with increasing temperature. Kinetic studies observed that the data fit the pseudo‐second‐order kinetic model better. In recovery attempts, more than 95% recovery was achieved with HNO3 and HCl. FTIR results showed that chitosan–montmorillonite interactions involved ‐NH, ‐OH, C=O, and C‐O bonds, while dye binding was mainly through OH bonds. SEM analysis revealed that montmorillonite reduced surface cracks and roughness, creating a more homogeneous structure, and more rough areas appeared after dye binding. As a result, the chitosan/montmorillonite composite significantly enhanced dye adsorption capacity.

Hydrothermal synthesis of Nb2O5-natural zeolite composite for enhanced adsorptive removal of anionic and cationic dye

The imperative to mitigate dye pollution from wastewater has propelled the exploration of efficient adsorbents. This study deals with the preparation and evaluation of Nb2O5-supported natural zeolite (NbX_NZ) for enhanced dye adsorption performance. A facile hydrothermal method was employed to prepare NbX_NZ with varying niobium precursor loadings. Comprehensive material characterization employing FESEM, EDX, TGA, XRD, and FTIR analyses elucidate the successful incorporation of Nb2O5, revealing altered morphological and thermal properties. The adsorption test exhibited a notable augmentation in adsorption capacity for Congo red dye, particularly with the Nb15_NZ sample, showcasing a nearly two-fold increase compared to the parent natural zeolite. The findings underscore the potential of NbX_NZ as promising materials for anionic dye adsorption, paving the way for advancing wastewater treatment solutions and further investigations into metal oxide-modified zeolites.

Biocomposite adsorbent (cross-linked chitosan + algae + montmorillonite) for methyl violet 2B dye removal: statistical modelling and optimisation

ABSTRACT Herein, a biocomposite of crosslinked chitosan polyethylene glycol diglycidyl ether (CS-PEDGE), montmorillonite (MMT), and food-grade algae (FGA) was successfully prepared by a hydrothermal technique. The resulting absorbent (CS-PEDGE/FGA/MMT) was assessed for its adsorption property with methyl violet 2B (MV 2B) a toxic cationic dye. The physicochemical properties of CS-EDGE/FGA/MMT were assessed via various analytical techniques, including BET, Elemental analysis, pHpzc, and spectroscopy (FTIR, XRD, SEM-EDX). The influence of three adsorption variables, namely adsorbent dose (A: 0.02–0.1 g/100 mL), solution pH (B: 4–10), and contact time (C: 10–420 min) on the rate of MV 2B dye removal was examined using the Box-Behnken design (RSM-BBD). The findings from the equilibrium isotherm and kinetic analyses suggest that the MV 2B dye adsorption onto the biocomposite surface follow the Freundlich model and pseudo-second-order kinetic models. The biocomposite adsorbent exhibits a maximum dye adsorption capacity (q max ) of 94.2 mg/g. The proposed MV 2B dye adsorption mechanism involves hydrogen bonding, n-π stacking, and electrostatic forces. This research demonstrates the unique structure and outstanding adsorption properties of CS-EDGE/FGA/MMT, which offers a viable solution for removal of detrimental MV 2B dyes from aqueous media.

Design of composite chitosan/algae/zeolite by freeze- or air-drying: A comparative adsorbent analysis for optimized removal of brilliant green dye.

A bio-composite material was developed that contains chitosan, food-grade algae, and zeolite for the removal of brilliant green (BG) dye. The synthesized bio-composite was dried via two different methods (air-drying; AD, and freeze-drying; FD). The physicochemical characterization of air-dried chitosan-algae-zeolite (Cs-Alg-Zl-AD) and freeze-dried chitosan-algae-zeolite (Cs-Alg-Zl-FD) were investigated by spectroscopy (FTIR, SEM-EDX, and XPS), diffraction (XRD), surface charge via pHpzc, specific surface area (SSA) and elemental analyses. The utilization of Box-Behnken Design (BBD) was intended to optimize the three input variables, which are adsorbent dosage, medium pH, and contact time. The adsorption optimization process yielded optimal conditions, which were verified through a desirability test and implemented in batch-mode equilibrium experiments. The Cs-Alg-Zl-FD has a higher specific surface area (SSA = 3.29 m2/g) compared to Cs-Alg-Zl-AD (SSA = 1.79 m2/g). The Cs-Alg-Zl-FD shows greater adsorptive removal of BG (98.6 %) over Cs-Alg-Zl-AD (88.6 %), in parallel agreement with differences in the SSA. Moreover, the maximum BG dye adsorption capacities of Cs-Alg-Zl-FD (119.5 mg/g) and Cs-Alg-Zl-AD (108 mg/g) at pH = 8.1 and 25 °C. The Freundlich model fits best with Cs-Alg-Zl-AD while Langmuir and Temkin models account for the Cs-Alg-Zl-FD dye adsorption. The Cs-Alg-Zl-FD shows greater dye adsorption over four adsorption cycles, as compared with the Cs-Alg-Zl-AD.

In-situ embedding of nanocylindrical Bi\(_{25}\)FeO\(_{40}\) into scaffold-C3N4 for enhanced Z-scheme photocatalytic degradation

The development of Z-scheme heterojunctions has emerged as an effective approach for boosting the photocatalytic activity. Herein, we fabricated of a direct Z-scheme heterojunction between scaffold-like C3N4 and nanocylindrical Bi25FeO40, which exhibits enhanced photocatalytic activity and dye adsorption capacity. The in-situ embedding of Bi25FeO40 within scaffold C3N4 promotes photogenerated carrier separation, leading to an optimized degradation rate of 0.0205 min−1 and a contaminant removal efficiency of 85.3%. This work paves a new path for the development of high-efficiency photocatalytic degradation.

Effective adsorbents developed from magnetic iron oxides and thiamin for the removal of hazardous organic contaminants

Among the removal techniques for organic contaminants in water, adsorption is a highly selected method due to many advantages in cost, simple process, and good efficiency. A green and straightforward synthesis for generating an iron oxide-grafted thiamin based adsorbents is developed. Their physicochemical and adsorption properties varied depending on the mixing ratio of ferrous chloride salt and thiamin. Adsorbents exhibited different magnetic properties owing to the presence of Fe3O4, α-Fe2O3, and γ-Fe2O3 crystalline phases. Their surface charges of iron oxide and functionalized thiamin-adsorbents were 25 mV and 30–52.3 mV, respectively while the C and N contents of thiamin ranged from 3.87–14.5% and 3.95–8.15% at different mixing ratios. Besides, scanning electron microscope (SEM) and thermogravimetric analysis (TGA) were used to analyze the morphology and thermal stability of adsorbents, respectively. This work investigated the effect of thiamin content in the material composition-based iron oxide on the adsorption capacity of anionic dyes. At the optimal condition (pH 5, an adsorbent dosage of 2 g/L, and a 30 mg/L concentration), the MO adsorption efficiency reached 77.56% in 30 min. Meanwhile, a 93.83% EBT was removed at pH 7, an adsorbent dosage of 2 g/L, and a 90 mg/L concentration at the same time. The adsorption mechanism follows the Langmuir isotherm model and the pseudo second-order (PSO) kinetic model. The adsorption processes are spontaneous and exothermic. The characteristic vibrations of functional groups of adsorbents were identified via Fourier transform infrared spectroscopy (FTIR). After four cycles, adsorbents could be employed albeit with a lower efficiency.

Impact of annealing temperature on the structure, magnetic properties, and organic dyes adsorption capacity of Fe0.5Co2.5O4 nanoparticles obtained by combustion

Impact of annealing temperature on the structure, magnetic properties, and organic dyes adsorption capacity of Fe0.5Co2.5O4 nanoparticles obtained by combustion

Turning trash into treasure: conversion of agroresidue rice straw into carboxymethylcellulose biopolymer

AbstractIn the present study, rice straw‐derived cellulose was converted into carboxymethylcellulose (CMC) using alkalization followed by an etherification reaction. The synthesis conditions for this chemical modification were optimized such that CMC with a high degree of substitution (1.02) was obtained. Infrared spectra of the synthesized CMC clearly showed an increased intensity of the C═O bond at 1600 cm−1, confirming successful carboxymethylation. Further, X‐ray diffraction analysis demonstrated a decrease in cellulose crystallinity owing to partial rearrangement from a crystalline to an amorphous phase during initial alkalization reaction. The obtained CMC biopolymer was subsequently cross‐linked to form a composite hydrogel matrix reinforced with bentonite clay. The hydrogel showed about 91% adsorption capacity for methylene blue dye as a model contaminant in aqueous media. Therefore, this study shows that lignocellulosic agrowaste is a rich source of cellulose, and its derivatives such as CMC possess the potential to realize the waste to wealth sustainability goal.

Assessment of the adsorption capacity of biochar samples obtained from agricultural biomasses

The study consists of adsorption tests on two samples of biochar, obtained from rice husk and coconut fiber biochar biomass, as well as a sample of charcarbon, both prepared under different conditions: macerated and non-macerated; impregnation with and without HCl and H3PO4; and washing or not with deionized water after impregnation. The test was performed in duplicate, for 30 min, with masses of 0.5 g; 0.3 g; 0.1 g; and 0.05 g, and an initial methylene blue concentration of 0.01 g∙L-1. The study was carried out with the objective of identifying, in the analyzed samples, the material with the greatest adsorption capacity of methylene blue dye, comparing the data with commercial activated carbon. The results identified removal above 70 % in both types of biochars, suggesting the feasibility of application as an adsorbent material to remove organic contaminants. The sample that most closely resembled the removal percentage of commercial activated carbon (98.84 %) was that of biochar obtained from coconut fibers, with 91.71 %. Thus, the research showed promise in studying the application and valorization of biochars, produced from agro-industrial waste, in adsorption processes.

Versatile organosilicone porous materials for the detection of nitroaromatics and the visualization of fingerprints

Achieving explosive detection and fingerprints visualization at the same time is of great significance. Towards this end, based on the cage structure and multiple reaction sites of octavinyl polyhedral oligomeric silsesquioxane (OVS), a series of multifunctional silicone porous materials OVSBs and OVSTs were designed and synthesized with 1,3,5-triphenylbenzene and 2,4,6-triphenyl-1,3,5-triazine. These porous materials have narrow pore size distribution, high specific surface area and pony-sized that smaller than 5 nm. The micropore volume ratio of porous materials can be changed by regulating the molar ratio of OVS to functional compounds. OVSB-2 shows excellent adsorption capacity for fluorescent dyes due to its highest specific surface area and high micropore volume ratio. OVSB-2 also has superior fluorescence characteristic, which can quickly detect nitroaromatic compounds within 20 s. This work provided a new method for expanding the application of silicone mesoporous materials in explosive detection and fingerprints visualization simultaneously.

Alkali treatment of polymer microspheres to efficiently remove rhodamine 6G from aqueous media

Core-shell microspheres composed of poly(styrene)-poly(styrene-methacrylic acid) (PSt-P(St-MAA)) are prepared using a simple emulsion polymerization technique. After synthesis, the particles are subjected to an alkaline treatment to create a rough surface on microspheres. The microspheres demonstrate high efficiency as an adsorbent for removing the cationic dye rhodamine 6G (Rh6G) from water. Several methods, such as FT-IR, SEM, TGA and particle size analysis, are used to characterize both the synthesized PSt-P(St-MAA) microspheres and the microspheres after Rh6G adsorption (PSt-P(St-MAA)/Rh6G). The effects of factors such as initial pH, dye concentration, temperature of the dyeing solution and contact time on dye adsorption capacity are systematically investigated using the batch adsorption method. The adsorption capacity is increased steadily with higher pH levels, dye concentration, temperature and extended contact time. The findings reveal that the adsorption capacity could reach as high as 214.2 mg/g at 25 °C. Furthermore, the adsorption kinetics indicate that the process adhered to a pseudo-second-order kinetic model. The equilibrium adsorption data fit well with the Langmuir isotherm model. Thermodynamic analysis reveals that the adsorption process is endothermic, spontaneous and characterized as physisorption. The results confirm that PSt-P(St-MAA) microspheres are highly efficient in removing cationic dyes from wastewater.

Preparation and characterisation of chitosan/bacterial Escherichia coli biocomposite for malachite green dye removal: modeling and optimisation of the adsorption process

ABSTRACT Herein, a new biocomposite was obtained by loading a bacterial suspension of Escherichia coli onto a chitosan matrix to produce a unique biocomposite (chitosan – E. coli) with effective properties for biosorption of malachite green dye from water. The physicochemical characteristics of the chitosan – E. coli biocomposite were studied by employing XRD, FTIR, FESEM-EDX and pHpzc. The optimisation of biosorption conditions was achieved using a Box-Behnken Design (RSM-BBD) to assess the effect of variables on the dye removal: biocomposite dose (0.02–0.1 g/100 mL), pH (4–8) and contact time (10–300 min). The optimal conditions for dye removal (84.3%) were achieved with a chitosan – E. coli dose of 0.1 g/100 mL, and a contact time of 160 minutes with a pH of 8. The equilibrium and kinetic experimental findings show the biosorption of malachite green dye by chitosan – E. coli follows the Langmuir and pseudo-second-order models, respectively. The maximum dye adsorption capacity (q max ) of malachite green for the chitosan – E. coli biocomposite was 164.7 mg/g, where the dye adsorption mechanism was attributed to several effects such as hydrogen bonding, n-π interactions, and electrostatic attraction. Thermodynamic analysis indicated that the biosorption process was spontaneous and endothermic, with a positive enthalpy change (ΔH° = 40.9 kJ/mol) and a negative Gibbs free energy (ΔG°) at all tested temperatures. The biocomposite chitosan – E. coli adsorbent exhibits favourable cationic dye adsorption that is anticipated to have utility for remediation of dye effluent in industrial wastewater.

Novel carboxymethyl cellulose-based hydrogel embedded with metal organic framework for efficient cationic dye removal from water

The rGO/CMC/β-CD (RCβ) hydrogel was synthesized from reduced graphene oxide (rGO), β-cyclodextrin (β-CD) and sodium carboxymethyl cellulose (CMC) by radical polymerization. A novel hydrogel adsorbent was created by growing the metal-organic framework (Cu-BTC) in-situ on RCβ hydrogel, which has excellent adsorption capacities for cationic dyes in wastewater. The adsorption parameters such as the amount of adsorbent, pH of solution and adsorption time were optimized through batch adsorption experiments. Under the optimal conditions of pH 6.0, adsorbent dosage of 0.01 g and experimental temperature of 25 °C, Langmuir isothermal model was used to fit the maximum adsorption capacities of methylene blue (MB), crystal violet (CV) and malachite green (MG), which were 892.66, 842.75 and 633.77 mg g−1, respectively. The fitting results of adsorption kinetics revealed that the pseudo-second-order model can describe the adsorption process better. Based on proposed studies, the dye molecules were adsorbed onto RCβ@Cu-BTC hydrogel mainly through electrostatic interaction, hydrogen bonding and π–π interactions. After five cycles, the adsorption efficiency of the RCβ@Cu-BTC hydrogel for MB, CV and MG can still reach 80 %, 77 % and 72 %, which shows that the adsorbent has good adsorption performance. Various adsorption experiments show that RCβ@Cu-BTC hydrogel has great potential in treating dye wastewater.

Binder‐Free 3D Printed Polyurethane/Bi‐MOFs Composites for Photocatalytic Degradation of Rhodamine‐B

AbstractThe modularization of metal‐organic‐frameworks (MOFs) powders is a crucial to bringing out the excellent properties of MOFs to industrial applications in water treatment, gas adsorption/separation and catalytic fields. To improve their practical application and recyclability, we propose a hybrid composite of biocompatible MOFs decorated on self‐supported three‐dimensional (3D) printed polyurethane acrylate (PUA) for wastewater treatment. In this study, we select Bi‐based MOFs with good visible‐light response and chemical stability as photocatalysts, two MOFs, bismuth gallate (Bi‐GA) and bismuth ellagic acid (Bi‐EA), are loaded into the mesh‐like PUA template by in‐situ growth method. And then, these two composites, PUA/Bi‐GA and PUA/Bi‐EA are used for the photocatalytic treatment of Rhodamine‐B (RhB) dye. The results demonstrate that PUA/Bi‐EA could reach the highest removal rate of 98.08 % under acidic conditions in 4 hours. The excellent performance should be attributed to unique structure that endow their high adsorption capacity for dyes, further, the adsorbed dye as a sensitizer enhances the utilization of sun‐light. This study provides a new composite for advanced photocatalytic water treatment and other environmental purification.

Incorporation of biomass-derived carbon dots and hydrochar into electrospun polylactic acid membranes: A sustainable zero-waste approach to highly efficient methylene blue, malachite green and neutral red dye removal

Recently, biomass-derived carbon dots (CDs) and hydrochar have gained widespread attention for environmental remediation. However, hydrochar is commonly regarded as carbon waste (CW) generated in the manufacture of CDs, and only a few reports have focused on the simultaneous application of CW and CDs. Herein, we propose a sustainable zero-waste approach for efficient dye removal by incorporating CDs and CW into electrospun membranes. CDs and CW were obtained via the one-step solvothermal carbonization of apple peels. The prepared CDs with an average size of 7.36 nm were first added to the electrospinning solution to obtain electrospun polylactic acid (PLA)/CDs fibers, followed by CW-integration via ultrasonication. The optimized PLA/CDs/CW composite exhibited high dye adsorption capacities of 141.99, 130.52, and 110.83 mg/g for neutral red, methylene blue, and malachite green, respectively. These dye adsorption capacities are significantly higher than those of the CD-loaded (70.15 mg/g for MB) or CW-loaded (52.34 mg/g for MB) composites, and are attributable to the rational loading of CDs and CW. Furthermore, the optimized composite exhibited remarkable chemical stability, stable reusability, and the ability to adsorb multiple dyes concurrently. This work provides new perspectives on the development of biomass-derived carbonaceous materials for environmental preservation and remediation.

Utilising date palm fibres as a permeable reactive barrier to remove methylene blue dye from groundwater: a batch and continuous adsorption study.

This study aimed to utilise cheap and abundantly available date palm fibre (DPF) wastes for the remediation of methylene blue (MLB) dye-contaminated groundwater. The DPF adsorbents were first prepared, followed by various characterisation analyses, including surface morphology, functional groups, and material structure. Subsequently, the DPF adsorbents were applied in the batch and continuous adsorption studies to assess the MLB dye removal from aqueous environments. The batch adsorption study achieved 98% maximum removal efficiency with a contact time, adsorbents dosage, initial pH, temperature, particle size, initial dye concentration, and agitation speed of 105min, 3g/L, 7.0, 45°C, 0.075mm, 50mg/L, and 150rpm, respectively. Langmuir was the best-fitted isotherm model depending on a higher correlation coefficient (R2 = 0.985), with a maximum monolayer dye adsorption capacity (qmax) of 54.204mg/g. Additionally, the second order was the best-fitted kinetic model (R2 = 0.990), indicating that MLB dye was removed through chemisorption. Besides, the positive enthalpy change (ΔH°) and negative Gibb's free energy (ΔG°) values verified the endothermic process and spontaneous adsorption. According to the impact analysis of initial dye concentrations and flow rates on the permeable reactive barrier (PRB) performance in the continuous adsorption study using the Thomas, Belter, and Yan models, the experimental results and predicted breakthrough curves reflected an excellent agreement (R2 ≥ 0.8767) and a sum of squared errors (SSE) ≤ 0.4834. In short, the results demonstrated DPF as an effective adsorbent material in PRB technology.

Carboxymethyl cellulose assisted morphology controlled synthesis of Mn3O4 nanostructures for adsorptive removal of malachite green from water

The physicochemical properties of manganese oxides and their different applications mainly depend upon their crystallite size, morphology, phase structure, and surface properties, which are again dependent on the preparation methods. So, a simple, cost-effective, and versatile synthesis method for such materials is highly desirable. Intending to accomplish this, herein we report the synthesis of Mn3O4 nanostructures by alkaline hydrolysis of the corresponding metal ions in an aqueous medium. The addition of a biodegradable polymer, sodium salt of carboxymethyl cellulose (Na-CMC) assisted the development of specific morphology, which is tunable by varying the concentration of the biopolymer. The spectroscopic, microscopic, and diffractometric analyses of the synthesized Mn3O4 nanostructures confirm that this particular simple technique is very effective in controlling the morphology of the formed nanostructures. These Mn3O4 nanostructures exhibit excellent adsorption capacity in the removal of malachite green (MG) from its aqueous solution under ambient conditions. The adsorption process is exothermic following pseudo-second-order kinetics with a maximum dye adsorption capacity of 489.68 mg g−1 according to the Sips isotherm model. The Mn3O4 nanostructures can be reused for up to five cycles of dye adsorption without significant loss of their adsorption performance.