Dye Adsorption Process Research Articles

Graphene oxide functionalized with L-asparagine applied to crystal violet dye removal from water and wastewater.

The efficiency of graphene oxide functionalized with L-asparagine (GO@L-Asn) as adsorbent for crystal violet (CV) dye removal from water and wastewater was investigated. The surface and textural properties of this new nanomaterial were characterized by pH at point of zero charge, Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmet-Teller technique. The main experimental variables involved in dye adsorption process were evaluated and optimized. Adsorption equilibrium was reached after 120min, using 25mL of 50mg L-1 CV, and 30mg of GO@L-Asn at pH 8 and 328K. The Freundlich isotherm model was the most appropriate to correlate the experimental data, showing a maximum adsorption capacity of 102.5mgg-1 (R2 = 0.992). The results of the kinetic study were fitted with the pseudo-first order model (R2 = 0.997). Thermodynamic calculations indicated that the CV removal was an endothermic, spontaneous, and favorable process. Characterization and modeling results showed that an adsorption mechanism involving physisorption was associated with CV removal. This novel adsorbent was applied to remove CV from samples of natural water and textile effluents, obtaining pollutant removal percentages up to 92.0%, which indicated the high efficiency of GO@L-Asn for the treatment of complex matrices.

Adsorption‐photocatalysis for methylene blue dye removal by novel Fe‐MOFs through defect engineering

AbstractIn recent years, metal–organic frameworks (MOFs) have attracted much attention in environmental pollution control. However, most MOFs still have problems such as low utilization of visible light and easy recombination of photogenerated electrons and holes. In this study, novel defective Fe‐MOFs with appropriate structural defects were prepared by solvothermal method and used to remove methylene blue (MB) in aqueous phase through adsorption and photocatalysis. Defective Fe‐MOFs have Fe content as high as 10.31% with specific surface area of 40.95 m2/g, which is beneficial for both dye adsorption and photocatalytic process. Defective Fe‐MOFs have spindle‐like structures with sizes ranging from 40 nm to 100 nm and an average size of 69.1 nm, as well as some irregularly shaped nanoparticles. Irregular stacking of these two kinds of structure makes Fe‐MOFs appropriate structural defects, large specific surface area, and mesoporous structure. Kinetics and isotherms of dye adsorption process are consistent with pseudo‐first‐order kinetic model and Freundlich isotherm model, respectively. Defective Fe‐MOFs can absorb MB dye rapidly, reaching adsorption equilibrium within 60 min. Dye adsorption process is endothermic, spontaneous, and entropy‐increasing process. After 180 min visible light illumination, dye photocatalytic efficiency of the defective Fe‐MOFs reaches 97.56% in the condition of MB concentration as high as 30 mg/L. Consequently, defective Fe‐MOFs with appropriate structural defects, porous structure, high Fe‐O content, and strong electron‐donating amino groups have huge potential applications in removing organic dyes from the aqueous solution by a green and environmentally friendly way due to their high dye adsorption and dye photocatalytic activity.

Effect of different ratio KOH treatment on neem bark in the formation of activated carbon: Adsorption characteristics study

In this study, mature neem tree bark (NB) was chemically transformed into an activated carbon (NBAC) through different ratios (1:1, 1:2, 2:1, 1:3, 3:1) of KOH and NB biomass. The obtained Neem bark-activated carbons (NBAC-1, NBAC-2, NBAC-3, NBAC-4, and NBAC-5) were tested for methylene blue (MB) dye removal efficiency. The NBAC-1 was found to be highly effective against MB dye. The NBACs have a low Brunauer-Emmet-Teller (BET) surface area (10.8 m2/g) with surface functional groups dominated by -OH and -CO. It is thermally stable up to 700°C, and its surface elemental composition is mainly carbon, oxygen, and potassium. The adsorption characteristics against MB dye show that 99.15% of dye from 100 mg/L initial concentration solution was removed with 4 g/L NBAC-1 dosage in 200 min of contact time at 50°C solution temperature, and pH of 10 (pHzpc = 7.85), resulting in an adsorption capacity of 24.79 mg/g. Kinetic studies indicated that the adsorption process of MB dye utilizing NBAC-1 adhered to the linear pseudo-second-order (R2 = 0.9726) and nonlinear Elovich model (R2 = 0.9419), signifying chemisorption, alongside the nonlinear Weber-Morris model (R2 = 0.9231), highlighting the significance of mass diffusion of MB dye onto the NBAC-1 surface in multilayers. Isotherm investigations favored better conformity with the Freundlich model, exhibiting a higher R2 value of 0.999, suggesting a heterogeneous multilayer adsorption mechanism. Adsorption thermodynamics analysis inferred that the adsorption was feasible (∆G = -4.342 KJ/mol), endothermic (∆H = +50.0203 KJ/mol), and demonstrated a high affinity of NBAC-1 towards MB dye (∆S = +168.2255 J/K/mol). Recyclability of the NBAC-1 adsorbent was also conducted to check for its sustainable usage.

Adsorption of synthetic cationic dyes from water (experimental, DFT and Monte Carlo studies) and treatment of real industrial wastewater using dextrose compound-modified layered double hydroxide

Dyes are a major water pollutant, and various methods have been employed to address the dye pollution in aqueous solutions. Currently, adsorption using inexpensive, abundant, and eco-friendly adsorbents like anionic clay is one of the simplest and most effective methods. This study aimed to investigate the fabrication of a novel layered double hydroxide modified with dextrose D@Mg1.5Zn0.5Al-LDH composite via co-precipitation route for removing both synthetic Rhodamine B (RhB) and Basic Fuchsin (BF) dyes from aqueous solutions. Various characterization techniques were employed to comprehensively understand the properties of the as-synthesized material, including XRD, FTIR, SEM-EDX, BET surface area analysis and zeta potential. To enhance the adsorption process of both basic dyes, experiments were conducted in a batch reactor to investigate the effects of key parameters such as reaction duration, initial dye concentration, pH, adsorbent dosage, and solution temperature. Cationic dyes uptake was predominantly observed within the first 10mins, reaching equilibrium in approximately 60mins. The D@Mg1.5Zn0.5Al-LDH composite achieved removal efficiencies of 99% for BF dye and 60% for RhB dye at pH 10, which are considerably higher than that of bare Mg1.5Zn0.5Al-LDH. The experimental adsorption data demonstrated excellent agreement with pseudo-second-order kinetics and the Langmuir isotherm. Density functional theory (DFT) calculations and molecular simulations had been employed to elucidate the adsorption mechanism of BF and RhB dyes onto the D@Mg1.5Zn0.5Al-LDH composite. Quantum parameters were calculated to characterize the electron density of the dyes which provided insights into their reaction behavior. Additionally, Monte Carlo simulations were employed to calculate the fluctuation energy, and to determine probability distributions of adsorption energy, and geometry of the small adsorption energy poses for BF/D@Mg1.5Zn0.5Al-LDH and RhB/ D@Mg1.5Zn0.5Al-LDH. These results offer equilibrium statistical conditions that explain the adsorption mechanism behaviors between the D@Mg1.5Zn0.5Al-LDH composite and BF/RhB dyes optimally. Importantly, the theoretical outcomes are in good agreement well with experimental results. Finally, the adsorption process is used to treat real industrial wastewater that mainly contains a mixture of Rhodamine B and Methylene Blue as the cationic dyes. The D@Mg1.5Zn0.5Al-LDH composite has shown good efficiency in the treatment of real industrial wastewater.

Using activated and modified adsorbent surfaces from banana peels to remove the green Janus dye:

In order for the process of removing pollutants, including dyes, from the aquatic environment to be effective, plant wastes such as banana peels were used as adsorbent surfaces by thermally activating them (ABP) and modifying them with iron oxide nanoparticles (MABP), which were characterized using Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) techniques. They were applied in the field of Janus green (JG) dye adsorption for the batch system and studied the effect of several factors (adsorbent weight, contact time, initial concentration, and temperature). Their data were analyzed kinetically using first- and second-order kinetic models and they were found to follow the second order. Their data were also analyzed through the equilibrium isotherms (Freundlich and Langmuir), and it was found to follow the Freundlich isotherm model. The thermodynamic functions for the dye adsorption process on both surfaces were calculated, through these functions, it was found that the dye adsorption process is spontaneous, easy, regular, and exothermic.

Preparation of dandelion flower extract-based polyvinyl alcohol-chitosan-dandelion-CuNPs composite gel for efficient bacteriostatic and dye adsorption

A multifunctional composite gel with efficient bacteriostatic and dye adsorption properties was prepared using polyvinyl alcohol, chitosan, and soybean isolate protein as carriers, CuNPs prepared by green reduction of dandelion extract as bacteriostatic agent, and glutaraldehyde as cross-linking agent. The composite gel showed good inhibition capacity of Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa with the diameter of inhibition zone of 27.0–28.3 mm by agar diffusion method. The composite gel antibacterial rate remained above 90 % after 14 days of preparation. After 6 times reuse of composite gel in water, the antibacterial rate remained above 90 %, proving its good stability and reusability. Adding dandelion extract and CuNPs greatly improved the gel antioxidant property, acquiring free radical scavenging rate at 95.6 %. This composite gel had good biocompatibility and adsorption performance, and the maximum adsorption amount of methylene blue and methyl orange was 40.36 mg/g and 41.81 mg/g, respectively. To sum up, the green composition of composite gel has good antimicrobial performance and high dye adsorption, which holds significant promising for treating the water body pollution and protecting the environment. To build cost-effective antibacterial and dye adsorption process on a large-scale, in-depth exploration about this topic is still needed to develop.

Pyrolytic carbon/Cloisite 30B/ZnFe2O4 as reclaimable magnetic nanocomposite for methylene blue decontamination

This study prepared a new magnetic nanocomposite of Cloisite 30B and pyrolytic carbon (PC). Its ability as an efficient adsorbent was studied to remove MB dye. The results of the physical-chemical properties showed that the desired absorbents were synthesized and modified PC using ZnFe2O4 and Cloisite 30B, improving their properties. The specific surface area of PC/Cloisite 30B/ZnFe2O4 (59.66 m2/g) was higher compared to PC (2.51 m2/g) and PC/ZnFe2O4 (37.66 m2/g). The magnetic saturation values of PC/ZnFe2O4 and PC/Cloisite 30B/ZnFe2O4 were 9.19 and 6.36 emu/g, respectively. The maximum dye removal using PC/Cloisite 30B/ZnFe2O4 (99.08 %) was determined at pH=10, adsorbent dose of 1 g/L, time of 50 min, temperature of 25 °C, and MB concentration 10 mg/L, respectively. The adsorption followed the pseudo-secondary-order model processes kinetic behavior. The adsorption process of MB dye using the desired absorbents was exothermic and spontaneous. The maximum removal capacity for PC, Cloisite 30B, and PC/ZnFe2O4 samples was determined to be 18.48, 28.49, and 43.47 mg/g, respectively, which shows the benefits of PC sample modification. Also, the PC/ZnFe2O4 and PC/Cloisite 30B/ZnFe2O4 samples can be reused in more than 5 and 7 steps, respectively, which shows their stability in adsorbing MB dye.

Bio-sourced multifunctional adsorbent of chitosan and adipic acid activated-dragon fruit peels for organic dye removal from water: Eco-friendly management and valorization of biomass

Employing sustainable biomaterials obtained from waste biomass and biopolymers provides a very promising method for eliminating organic dyes from wastewater. This study presents a novel adsorbent of modified dragon fruit peels and chitosan, addressing wastewater treatment and environmental waste management. Precisely, a bio-sourced multifunctional (high level of functional groups) adsorbent (hereinafter, CHS/DFP-ADP) was developed from chitosan and adipic acid activated-dragon fruit (Hylocereus polyrhizus) peels. This biomaterial was applied to effectively adsorb organic pollutants (safranin O dye, SAF-O) from water. The adsorption variables, namely A: CHS/DFP-ADP dosage (0.02–0.08 g), B: pH (4–10), and C: duration (10–40 min), were modeled and optimized using the Box-Behnken Design (BBD). The results of the BBD model showed the optimum adsorption parameters for achieving the highest level of SAF-O removal (94.83 %) were as follows: CHS/DFP-ADP does = 0.049 g, the pH ∼ 10, and the contact duration = 40 min. The experimental results on the dye adsorption by CHS/DFP-ADP demonstrated conformity with the pseudo-first-order and Freundlich models. The biomaterial demonstrated a significant capability to adsorb SAF-O dye, with an adsorption capacity of 607.2 mg/g. The adsorption process of the cationic dye on the CHS/DFP-ADP involves several interactions, such as Yoshida H-bonding, electrostatic forces, n-π, and H-bonding. This work aligns with the principles of green chemistry and sustainable development, offering an innovative approach to tackle environmental concerns and promote the circular economy. The present effort meets several Sustainable Development Goals (SDGs), such as SDG 6 (Clean Water and Sanitation), SDG 12 (Responsible Consumption and Production), SDG 13 (Climate Action), and SDG 14 (Life Below Water).

Use of Brushite as Adsorbent for the Removal of Anionic and Cationic Dyes Present in Aqueous Solutions

Currently, water pollution caused by dyes is a serious problem since they are toxic and carcinogenic to living beings. To reduce the presence of these contaminants, natural adsorbents have been considered as they are easy to obtain, inexpensive, and have high removal efficiency. In this work, the adsorption process using natural brushite (nDCPD) was studied for the removal of phenol red (PR), achieving a removal rate of 99.15% and an adsorption capacity of 82.24 mg/g, and gentian violet (GV), achieving a removal rate of 97.03% and an adsorption capacity of 74.22 mg/g. Equilibrium adsorption occurs for both dyes in multiple layers on the surface. The adsorption process is spontaneous for both dyes. The kinetics of the adsorption process involve using a single active site on the surface for PR adsorption, while for GV, two active sites on the surface are required. Analysis via FTIR, EDS, and XRD revealed various mechanisms that intervene in the adsorption process of both dyes on the surface of nDCPD, such as electrostatic forces, functional groups, physisorption, and ion exchange.

Kinetics of the decomposition of reactive black 5 on carbon nanostructured adsorbents

Textile industry effluents, containing vast quantities of toxic organic pollutants and synthetic dyes like Reactive Black 5 (RB5), pose a significant environmental threat. RB5 contamination can harm ecosystems and human health, necessitating effective treatment for water recycling and compliance with quality standards. Traditional methods like filtration often fall short in removing dye chemicals. This study examines the efficiency of nanocarbon-based adsorbents in removing RB5 from textile industry effluents. RB5 solutions at concentrations of 10 µM, 30 µM, 60 µM and 100 µM were investigated and characterized using scanning electron microscopy (SEM) and UV-Vis spectrophotometry. Activated carbon (AC) demonstrated the highest degree of RB5 decomposition, outperforming graphene nanoplatelets (GNPs) and graphene oxide (GO) and offering a promising solution for mitigating textile wastewater pollution. Kinetic studies revealed that RB5 adsorption follows a pseudo-second-order model for all adsorbents. The rate constants were determined using PSO kinetics and they were comparable with the rate constants of prior studies, indicating the applicability of the model to the study of the kinetics of similar dye adsorption and decomposition processes.

Alginate functionalized sugarcane cellulose-based beads to improve methylene blue adsorption from aqueous solution

The study was carried out with the goal of synthesizing composite bead of cellulose, chitosan functionalized by sodium alginate using as an efficient and applicable adsorbent for methylene blue removal. Fabricating parameters of the material synthesis process like cellulose mass, sodium hydroxide concentration, immersing time and sodium alginate concentration were assessed in detail. The dye adsorption performance in water under the influence of pH, contact time, dye initial concentration, the material mass, shaking speed, temperature was also thoroughly evaluated. The results of advanced analyses showed that the beads were successfully synthesized with a rough surface and mesoporous structure. The adsorption isotherm and adsorption kinetics of dye adsorption process exhibited that the process was consistent with the Freundlich adsorption isotherm and the pseudo-second-order kinetic model, indicating a favorable physical adsorption process with multilayer of the dye on the adsorbent surface. The intra-particle diffusion model showed the strong dye adsorption by the beads occurred during the first two and half hours. The adsorbent could maintain its adsorption performance of 86 % for three times of regeneration. Finally, this study provided a recyclable and effective adsorbent for dyes separation from water.

Designing and computational investigation of acceptor for dye-sensitized solar cell and nonlinear optical properties

Systematic strategies have been employed to designing the acceptor part for dye sensitized solar cell and nonlinear optical properties using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. The designed dyes have followed donor-π-spacer-acceptor (D-π-A) pattern. For designing of organic dyes, we have utilized the 7,7,8,8-tetracyanoquinodimethane (TCNQ) unit as a accepter for dye-sensitized solar cells (DSSCs) and investigating the impact of various electron acceptor in the designed framework. For designing of such framework, we have employed B3LYP level of theory and 6–311+G(d,p) basis set. Initially, the optoelectronic properties of the metal free dyes are calculated based on different acceptors and then we have designed (2–9) dyes. The designed dyes which contain TCNQ-based acceptors show enhance power conversion and optoelectronic properties than that of reference one. We have calculated different parameters such as dipole moments (μnormal), band gap (Egap), electron injection (ΔGinjection), driving force of regeneration (ΔGregen), and nonlinear optical (NLO) properties. We have also investigated the essential process of dye adsorption on titanium dioxide (TiO2) surfaces. The calculated values of μnormal (17.79 & 22.37 debye) and Egap (0.57 & 0.88 eV) for dyes 8 &9 respectively which are more efficient than that of dye 1. Furthermore, the calculations for density of state (DOS) and partial density of state (PDOS) validate the FMO analysis and demonstrate effective charge transfer from the HOMO to LUMO. Further, the designed dye molecules were exhibiting enhanced and gigantic nonlinear optical properties. In comparison to cyanoacrylic acid, the TCNQ group has the potential to function as a superior acceptor in upcoming applications of DSSCs.

Synthesis of porous carbons for the fixing of cationic molecules in aqueous solution

In Africa, the calyxes of the Hibiscus sabdariffa are widely used to produce a fresh fruit juice, known in Benin as bissap. The stems from this production have no potential use and are therefore an environmental problem. The parietal composition of these stalks revealed a high level of lignin (31 ± 1 %) and cellulose (35 ± 1 %). They can therefore be converted into activated carbon for various applications. In this study, the stems were transformed into activated carbons at moderate temperature using orthophosphoric acid (H3PO4) as the activating agent. The physicochemical, structural, and textural properties were determined. Adsorption kinetics and isotherms were studied and modelled. Porous carbons give specific surface areas equal to 1066 and 1053 m2.g−1 respectively for 2:1 and 4:1 ratios according to the B.E.T-Rouquerol model. Similarly, the said porous carbons give specific surface areas equal to 991 and 975 m2.g−1 respectively for 2:1 and 4:1 ratios according to the 2D-NLDFT model. Using the latter model, the pore size distribution is predominantly microporous, with the Vµ/VT (%) ratio increasing to 56 %. Thermogravimetric analysis of the porous coals showed favourable fixed carbon levels (≈ 60 %). The adsorption kinetics of methylene blue on activated carbons is governed by the pseudo-second order kinetic model indicating that the dye adsorption process is globally controlled by chemisorption. The results of the modelling of the methylene blue adsorption isotherms shown that the Langmuir model is the most credible model that best describes these experimental results, with 588 and 526 mg.g−1. These activated carbons are good candidates for the development of bio-sourced filters for the treatment of industrial wastewater.

New study of the adsorption mechanism of different dye molecules by high porous sludge activated carbon produced from a dairy-treatment effluent plant

In this study, a high-quality porous sludge-activated carbon from a dairy-treatment effluent plant in México (ACSDM) was produced, characterized, and investigated in the adsorption of 8 different dyes. The main focus was establishing how the dyes' molecular characteristics affect adsorption. So, the intrinsic characteristics of the different dye molecules were correlated with the experimental adsorption data. ACSDM proved high quality, considering their textural properties and physical-chemical characteristics. Adsorption was efficient using the natural pH of each dye solution and 1 g L−1 of ACSDM. The highest adsorption capacities were obtained in the following order: Methylene Blue (MB) (998.44 mg g−1), Crystal Violet (CV) (795.65 mg g−1), Fuchsine (F) (342.52 mg g−1), Direct Blue 86 (DB-86) (306.36 mg g−1), Alizarin Green (AG) (303.25 mg g−1), Reactive Black 5 (RB-5) (259.82 mg g−1), Methanil Yellow (MY) (252.81 mg g−1) and Amaranth Red (AR) (251.12 mg g−1). These results were obtained at 55 °C (endothermic process), except for MY, where the adsorption was exothermic (25 °C). Freundlich was the model that best fitted the DB-86, MB, and CV equilibrium data. While the Langmuir and Tóth models best fit the RB-5, AR, and MY isotherms. Tóth also best represented the F and AG data. Kinetic curves demonstrated that adsorption occurred faster for dyes MB, F, CV, MY, AR, and RB-5, respectively, reaching 90 %-99 % of their saturations in the first 30 minutes. Meanwhile, the adsorption of AG and DB-86 only about 85 % of the saturation occurred. The study indicated that molecular volume is the major variable in the dye adsorption process, as well as some individual chemical characteristics of the molecule.

Adsorption of Brilliant Scarlet 3r dye onto Corn Silk as Agricultural Waste in Neutral Medium

This study investigates the adsorption of Brilliant Scarlet 3r dye (BS 3r) onto corn silk (CK), an agricultural waste, in a neutral medium. The characteristics of corn silk as an adsorbent were analyzed using Fourier transform infrared spectroscopy (FTIR) and Atomic force microscopy (AFM). Batch adsorption experiments were conducted to examine the effects of corn silk weight, initial BS 3r concentration, adsorption period, adsorption temperature, and pH of the medium on the adsorption process. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms models were used to represented the equilibrium experimental date, the obtained values of correlation coefficient R2 indicated that the adsorption followed the Langmuir isotherm. The kinetics analysis results showed that the adsorption of Brilliant Scarlet 3r dye (BS 3r) onto corn silk followed the pseudo second-order model (PSOM), indicating its suitability for describing the adsorption kinetics. Thermodynamic parameters, including ∆G˚, ∆H˚, and ∆S˚, indicated that the adsorption process of BS 3r dye onto corn silk was spontaneous and exothermic in nature.

Interfacial interactions in aqueous systems of poly(ε-caprolactone)-co-poly(2-hydroxyethyl methacrylate) hydrogel with dye molecules in synthetic wastewaters

The use of dyes is widespread in the textile business, having various detrimental effects on humans and ecosystems. When dying, both cationic and anionic dyes are used. A lot of studies have been conducted in order to find an effective eco-friendly solution to resolve this issue. In this study, we recommend the use of an amphoteric and amphiphilic hydrogel consisting of ε-caprolactone and 2-hydroxyethyl methacrylate which are both biodegradable and cost-effective. The synthesis of this material was confirmed by FTIR, XRD, and SEM. The parameters under which the composite was adsorptively examined were the effects of pH, temperature, and contact time. It was found that the kinetics followed the pseudo fractal-like first order kinetic model for Μethylene Blue, while for Remazol Brilliant Blue R, both the pseudo fractal-like first order and the pseudo-second order models describe the data equally well. Thermodynamic analysis indicated that the adsorption process of both dyes was endothermic and spontaneous. Reuse experiments showed that their removal efficiency was retained at high levels, while stability studies revealed that the hydrogel retains its structural integrity, even at extreme pH values. Finally, the poly(ε-caprolactone)-co-poly(2-hydroxyethyl methacrylate) approach appears to be a viable strategy for removing dye residues from wastewater that is both successful and ecologically acceptable.

Investigation of Eucalyptus camaldulensis and Tamarix aphylla species' capacities for methylene blue removal in wastewater and heavy metal remediation in soil.

In the contemporary landscape, the reuse of wastewater holds paramount significance. Concurrently, wastewater carries an array of pollutants encompassing chemical dyes and heavy metals. This study delves into the potential of Tamarix aphylla (TA) and Eucalyptus camaldulensis (EC) species for mitigating heavy metals in soil and eliminating methylene blue dye (MB) from wastewater. The research begins with assessing the dye adsorption process, considering pivotal factors such as initial pH, adsorbent dosage, initial dye concentration, and contact time. Outcomes reveal EC's superiority in dye removal compared to TA. As a bioremediation agent, EC exhibits a 90.46% removal efficacy for MB within 15 min, with pH 7.0 as the operative condition. Equilibrium analysis employs Temkin (T), Freundlich (F), and Langmuir (L) isotherms, revealing an excellent fit with the L isotherm model. The study delves further by probing surface adsorption kinetics through pseudo-first-order (PFO) and pseudo-second-order (PSO) models. Furthermore, to discern the divergent impacts of EC and TA on soil heavy metal reduction, soil samples were collected from three distinct zones: an untouched control area, alongside areas where EC and TA were cultivated at the Yazd wastewater site in Iran. Heavy metal levels in the soil were meticulously assessed through rigorous measurement and statistical scrutiny. The findings spotlight TA-cultivated soil as having the highest levels across all examined factors. Ultimately, EC emerges as the superior contender, proficiently excelling in both MB eliminations from wastewater and heavy metal amelioration in the soil, positioning it as the preferred phytoremediation agent.

Surface methodology for optimized adsorption of hazardous organic pollutant from aqueous solutions via novel magnetic metal organic framework: Kinetics, isotherm study, and DFT calculations

An efficient way to remove Janus Green B (JGB) dye from contaminated water sources is using of magnetic cerium (III) metal–organic framework (MCe-MOF). Analytical methods such as PXRD, TEM, FESEM, FT-IR, PZC, and XPS were used in the characterization of the MCe-MOF microspheres in order to assess the phase, crystallinity, shape, surface characteristics, and chemical composition of the MCe-MOF material. Impressive physical characteristics of the synthesized MCe-MOF material included a high surface area of 1340.05 m2/g. Conversely, MCe-MOF’s magnetic saturation (MS) was measured at 36.47 emu.g−1. The purpose of the study was to determine if MCe-MOF could effectively remove JGB dye from wastewater by adsorption. Adsorption settings that were studied included pH, adsorbent dose, beginning dye concentration, contact time, and temperature. The JGB electrical characteristics, reactivity, and shape were ascertained through the application of density functional theory (DFT). The placement of electrophilic and nucleophilic attack sites is in good agreement with the molecular orbitals (HOMO and LUMO) and MEP results, according to DFT. Based on the findings, MCe-MOF had a high capacity for adsorbing JGB dye, with an adsorption data fit by pseudo-second-order kinetic models and the Langmuir isotherm. It was evident from the adsorption energy of 27.8 kJ.mol−1 that chemisorption was the mode of adsorption. The optimal conditions for attaining a high adsorption capacity were found to be pH 8 and 0.02 g of MCe-MOF dose. The adsorption process of JGB dye onto MCe-MOF was seen to be spontaneous, endothermic, and random, as indicated by the temperature-dependent increases in the thermodynamic parameters ΔGo, ΔHo, and ΔSo. The adsorption process was optimized through the application of Response Surface Methodology and Box-Behnken design (RSM, BBD). The successful removal of dyes from the MCe-MOF material was made possible by these methods. While π-π bonding happens through the interaction of aromatic rings, chemisorption entails the formation of chemical interactions between the adsorbate and adsorbent. Electrostatic interactions arise from the attraction or repulsion of charges between the adsorbate and adsorbent, and pore-filling happens when the adsorbate fills the adsorbent’s pores. For the removal of JGB dye from wastewater, MCe-MOF exhibits great potential as an adsorbent because of its numerous adsorption processes and high adsorption capacity.

Effect of lightweight composite brick’s waste on the removal of malachite green from aqueous solution and phytotoxicity assessment

ABSTRACT This study investigates the removal of malachite green (MG) dye by adsorption process using as adsorbent a waste byproduct from lightweight composite brick production, composed of clay and 5 wt.% argan nut shell and designed as waste bricks (WB). Characterization of the adsorbent (WB) was conducted using several techniques such as XRD, XRF, FTIR, etc. Optimal conditions for the adsorption process of MG dye with WB were carried out, considering adsorbent dose (0.02–0.4 g/mL), pH (2–12), contact time (0–360 min), and MG dye concentration (20–210 mg/L). The obtained outcomes indicated that the optimal parameters for a dye concentration of 20 mg/L are an adsorbent dose of 0.15 g/mL, a pH of 10, and an adsorption time of 180 minutes. Furthermore, kinetic, isotherm, and thermodynamic adsorption have been evaluated. The results highlighted that the pseudo second-order and Langmuir model described accurately the adsorption process with an adsorption capacity of about 2.66 mg/g and 23.48 mg/g respectively. While the thermodynamic study conducted at four temperatures (298 K, 308 K, 318 K, 328 K) revealed that the adsorption process is spontaneous and endothermic in nature. Finally, a phytotoxicity test of malachite green dye solutions was carried out using wheat and lentil seeds confirming the treatment effectiveness of the adsorbent.

Sulphonated date palm (Phoenix dactylifera) stone via microwave‑assisted H2SO4 activation: optimisation with desirability function for methylene blue adsorption

ABSTRACT In this work, a sulphonated date palm (Phoenix dactylifera) stone (SDPS) was produced as a cost-effective and renewable adsorbent for the removal of a cationic dye called methylene blue (MB). The production process involved the use of microwave irradiation combined with H2SO4 activation under the condition of 600 W microwave radiation for 15 min. The physicochemical characteristics of SDPS were evaluated using various analytical techniques, including XRD, BET, FTIR, pHpzc, and SEM. The Box-Behnken design (BBD) was employed to optimise key adsorption variables, including A: SDPS dosage (0.02–0.1 g/100 mL), B: pH (4–10), and C: contact time (5–25) min. According to the BBD model, the most effective removal of MB (98.4%) occurred with a dosage of 0.06 g/100 mL of SDPS, a pH of 10, and a contact time of 25 min. The rate of adsorption of the MB dye followed a pseudo second order (PSO) model, whereas the equilibrium adsorption was described by the Langmuir and Temkin models. The maximum adsorption capacity (q max ) of SDPS for MB dye was found to be 122.3 mg/g at 25°C. Several contributions to the MB dye adsorption process include electrostatic interactions, H-bonding, pore filling, and π-π stacking onto the SDPS adsorbent surface.