Adsorption Capacity For Methyl Orange Research Articles

Development of Recoverable Magnetic Bimetallic ZIF-67 (Co/Cu) Adsorbent and Its Enhanced Selective Adsorption of Organic Dyes in Wastewater.

In the critical domain of wastewater treatment, the development of cost-effective, durable, and recyclable adsorbents with high adsorption capacities remains a significant challenge. This study introduces a novel magnetic bimetallic Metal-Organic Framework (MOF) adsorbent, MZIF-67-Co/Cu, doped with copper ions. The MZIF-67-Co/Cu adsorbent was successfully synthesized and structurally characterized, demonstrating remarkable selectivity for removing methyl orange (MO) from water. This high selectivity is attributed to the adsorbent's high porosity and Lewis base properties at the coordinating metal ion center. The incorporation of Cu ions significantly enhances the porous architecture and increases the number of metal adsorption sites, leading to an impressive maximum MO adsorption capacity of 39.02 mg/g under optimized conditions (0.5 g/L adsorbent concentration, pH 3.0, 250 rpm agitation speed, adsorption time > 10 min). The adsorption kinetics closely follow the pseudo-second-order model, and the isotherm data fit well with the Langmuir model. The primary adsorption mechanisms involve electrostatic attraction and mesoporous interaction. This study highlights MZIF-67-Co/Cu as a highly efficient adsorbent with magnetic recovery capabilities, positioning it as a promising candidate for addressing critical issues in wastewater treatment.

Versatile and durable polyvinyl alcohol/alginate/gelatin/quaternary ammonium chitosan/Fe3O4 particles hybrid hydrogel beads: adsorption capabilities for cleaning pollutants

A novel hybrid hydrogel bead (HHBFe) composed of polyvinyl alcohol/sodium alginate/gelatin/quaternary ammonium chitosan (PVA/GA/SA/QCS) and Fe3O4 magnetic nanoparticles was developed through green cross-linking of Ca2+ and tannic acid (TA) combined freeze-thaw method. HHBFe exhibited a good spherical shape, porosity, magnetic properties, and excellent mechanical properties and durability. The adsorption capacity of HHB and HHBFe towards methyl orange (MO), tetracycline (Tc), and Cr (VI) was systematically studied and compared. Results revealed similar adsorption capacities for MO and Cr (VI) between HHB and HHBFe, while the presence of Fe3O4 significantly enhanced Tc adsorption, indicating the versatile adsorption functions of HHBFe. Adsorption kinetic followed the pseudo-second-order model, with external diffusion and intra-particle diffusion controlling process. The adsorption data were consistent with the Langmuir isothermal adsorption model, indicating predominantly monolayer adsorption of pollutants by beads. Notably, the beads exhibited easily regenerated, maintaining 60 % of initial adsorption capacity after 5 cycles, particularly for Tc and Cr (VI). The good adsorption performance of HHBFe can be attributed to the strong interaction between their multi-functional groups including phenolic hydroxyl groups, carboxyl groups, amino groups, etc., and pollutant molecules. The multifunctional HHBFe beads prepared in this study and the results obtained with three completely different types of pollutants provide reliability support for their use in different wastewater treatment fields and even in the field of drug carriers.

Ultrasonic assisted removal of methyl orange and bovine serum albumin from wastewater using modified activated carbons: RSM optimization and reusability

Abstract The removal of industrial pollutants from water remains a significant challenge in water treatment processes. This study investigated the efficacy of powder-activated carbon (PAC), thermally modified PAC (TPAC), and chemically modified PAC (CPAC) for removing bovine serum albumin (BSA) and methyl orange (MO) from simulated wastewater. After undergoing treatment, the BET surface area of TPAC increased to 823 m2/g, while that of CPAC increased to 657 m2/g compared to the initial surface area of pristine PAC, which was 619 m2/g. Batch adsorption experiments assisted by ultrasonication were conducted to evaluate the impact of solution pH, initial concentration, and contact time on the adsorption capacities (qmax) of BSA and MO. TPAC demonstrated superior performance, achieving qmax values of 152 mg/g for MO and 133 mg/g for BSA, compared to PAC, which provided qmax values of 124 mg/g and 112 mg/g for BSA, respectively. Furthermore, pH levels of 3 and 5 were identified as highly effective for the removal of MO and BSA from water, respectively. The adsorption kinetics of both MO and BSA followed pseudo2nd-order (R2 > 0.99) reaction kinetics under both batch and ultrasonic conditions, confirming the removal of contaminants through chemisorption. The adsorption trends also satisfied the Langmuir isothermal model, indicating the formation of a uniform monolayer during the adsorption process of these contaminants. To understand the simultaneous effect of all the variables, response surface methodology (RSM) using central composite design (CCD) was used to predict the adsorption capacities of CPAC. After five adsorption cycles, the removal efficiencies of MO (from 98% to 80%) and BSA (from 55% to 40%) decreased in the CPAC system. The results suggested that CPAC can be effectively utilized to remove MO from wastewater.

Preparation of WO3/MoO3-x composites from W–Mo alloy scrap and it's adsorption-photocatalytic properties

A straightforward hydrothermal method was employed to fabricate WO3/MoO3 composites, with the addition of ascorbic acid (Vc) for modification, resulting in WO3/MoO3 composites with oxygen defects (WO3/MoO3-x). WO3/MoO3-x exhibits exceptional adsorption-photocatalytic properties, demonstrating strong adsorption capability for dyes achieved through hydrogen bonding and electrostatic interactions. For all products, adsorption rates for methylene blue (MB) exceeded 95 % when reaching adsorption equilibrium. Moreover, an increase in molybdenum (Mo) content endows the samples with enhanced adsorption capacity for methyl orange (MO) and improved photocatalytic performance. Dynamic fitting of the samples revealed that when the W/Mo molar ratios is 2:8, the product W2Mo8-Vc, exhibits the highest photocatalytic activity. After 3 h of illumination, W2Mo8-Vc achieves a remarkable photocatalytic efficiency of 98 % for dyes. This research not only successfully recycles W–Mo alloy scrap but also yields WO3/MoO3-x composites with adsorption-photocatalytic properties, offering a novel approach for the recycling of W–Mo secondary resource.

Fabrication of high-crystallinity hydrazone‐linked fluorescent covalent organic framework and its sulfonated material for the design of sensing and adsorption dual-functional platforms

Hydrazone-linked fluorescent covalent organic frameworks (COFs) with high crystallinity exhibit remarkable stability under acid-base conditions and in various organic solvents, maintaining structural integrity for cyclic utilization in sensing and adsorption processes. Consequently, developing new high-crystallinity hydrazone-linked fluorescent COFs is of significant importance. Notably, post-modification can enhance the detection diversity, selectivity, and adsorption performance of these COFs. Herein, a new hydrazone-linked fluorescent COF (namely COF-YYL) with high crystallinity was synthesized using 2,5-bis(allyloxy)terephthalohydrazide (DHzDAll) and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)tribenzaldehyde (TTB) as precursors at room temperature. COF-YYL demonstrated superior characteristics including a high specific surface area (653.33 m2·g−1), good chemical and thermal stability, and dual-functionality in detecting methyl orange (MO) and Cu2+ with limits of detection (LODs) of 33 nM (2.1 ng·mL−1) and 1 ng·mL−1, respectively, and an MO adsorption capacity of 112.81 mg·g−1. To increase functional diversity, COF-YYL underwent post-modification via “click” chemistry between the double bonds on DHzDAll and −SH on 3-mercapto-1-propanesulfonic acid sodium salt (MPS), yielding COF-SO3Na. Compared with COF-YYL, COF-SO3Na exhibited a higher specific surface area (815.23 m2·g−1), better dispersion performance, and richer functional group properties. Leveraging these advantages, COF-SO3Na served as a dual-function platform for detecting and adsorbing four cationic dyes including brilliant green (BG), crystal violet (CV), malachite green (MG), and methylene blue (MB), with satisfactory LODs (170 ng·mL−1) and good adsorption capacities ranging from 98.94 to 162.87 mg·g−1. Further, COF-YYL and COF-SO3Na were used to analyze related analytes in tap water samples, achieving satisfactory recoveries. This study introduces a new high-crystallinity hydrazone-linked fluorescent COF, along with its sulfonated material, increasing the diversity of detection and adsorption platforms.

Highly efficient adsorption of congo red and methyl orange dyes using mesoporous α-Mn2O3 nanoparticles synthesized with Pyracantha angustofolia fruit extract

Due to the many applications of manganese oxides in water treatment, this research aimed to synthesize α-Mn2O3 nanoparticles through a green method and investigate the dye adsorption capacity of them. The α-Mn2O3 nanoparticles were successfully synthesized using KMnO4 and aqueous extract of Pyracantha angustofolia fruits under hydrothermal conditions and calcination. The products were identified using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), and scanning electron microscopy (SEM) analyses. The adsorption capacity of methyl orange (MO) and Congo red (CR) dyes were evaluated at different concentrations (25, 50, and 75 ppm) using α-Mn2O3 nanoparticles. Results revealed the spherical and porous structure of α-Mn2O3 nanoparticles with a specific surface area of 21.7 m2.g-1. Dye removal significantly increased with pH decrement. The adsorption capacity for MO and CR was 73.07 and 70.70 mg.g−1, respectively. The adsorption data of both dyes followed a pseudo-second-order kinetic model. The best fitted models for MO and CR adsorption were the Langmuir isotherm and the Dubinin–Radushkevich, respectively. In addition, a possible adsorption mechanism was proposed for both dyes. The findings showed that α-Mn2O3 nanoparticles are very efficient adsorbents for removing anionic dyes.

Rapid eco-friendly selective dye removal using modified chitosan-based sponges: Synthesis, characterization, and application

The ongoing challenge of water scarcity persists alongside a concerning rise in water pollution driven by population expansion and industrial development. As a result, urgent measures are imperative to address the pressing need for a clean and sustainable water supply. In this study, a sustainable and green approach was utilized to prepare four chitosan-based sponges from a chemically modified chitosan with different alkyl chains in aqueous medium and at room temperature. The resulting sponges displayed excellent stability in water with outstanding dye removal efficiency. The adsorption capacity was associated with the alkyl chain length incorporated to the polymer backbone. All sponges displayed a high adsorption capacity of methyl orange (MO) ranges between 238 and 380 mg g−1, while a low capacity were obtained for methylene blue (MB) and Rhodamine B (RB). Competitive adsorption experiments were conducted on binary and ternary mixtures to assess the selective removal of MO from a mixture of dyes in which the separation factor was found to be ranging between 1.6 and 32. The adsorption kinetics isotherms of all sponges followed the pseudo-second-order, and the Langmuir model was found to be more suitable than the Freundlich for the adsorption of MO on the sponges. The chitosan-based sponges showed stable performance, robustness and reusability over 5 adsorption-desorption cycles, indicating their great potential for water treatment applications.

Liquidizing crystal MIL-100(Fe) to coating silica powder for purifying wastewater

Although MIL-100(Fe) was regarded as an ideal material for the environmental remediation, it could not be applied in practical because of the potential eco-environmental risk and cost. In this work, a novelty strategy of liquidizing crystal MIL-100(Fe) was posted for the first time through inhibiting the crystallization process and forming physical MIL-100(Fe) gel. Due to this MIL-100(Fe) sol–gel, MIL-100(Fe) could easy cover on the surface of silica powder (SiO2) through simple soaking operation. MIL-100(Fe) covering on SiO2 (MIL-100(Fe)@SiO2) could be quickly separated from wastewater spontaneously owing to the carrier of SiO2, even in a tank of 2.0 m, which made it possible for purifying wastewater in practical. MIL-100(Fe)@SiO2 could remove phosphate with a removing ratio of closing 100 % at an initial concentration of 10 mg/L, while more than 95 % towards methyl orange (MO). The removing ratio of MO by MIL-100(Fe)@SiO2 did not obviously decrease when the concentration of MO increased to 100 mg/L. And the adsorption performance of phosphate did not affect by pH among 3.0–9.0. The adsorption amount exceeded 50 % of maximum adsorption capacity for phosphate within 30 min, while 90 % for MO. Monodentate mononuclear coordination could explain the adsorption of phosphate by MIL-100(Fe)@SiO2. The N atom in MO might be acted as Lewis acid to coordinate with MIL-100(Fe)@SiO2. After adsorption, the P-saturated and MO-saturated MIL-100(Fe)@SiO2 could be effectively regenerated by the dilute HCl and NaOH solution, respectively. The recovery ratio of adsorption capacity for phosphate and MO were up to 97.7 % and 71.6 %.

Removal of methyl orange dye by high surface area biomass activated carbon prepared from bamboo fibers

To obtain a green biomass-activated carbon with abundant pores for the high-efficiency removal of dye, this study fabricated bamboo fiber-based activated carbons (BFACs) via a one-step activation strategy with the assistance of ZnCl2 as the activator for the removal of methyl orange (MO). The results showed that the specific surface area (SSA) of BFAC-500 activated at 500 ℃ was as high as 2512 m2/g with a total pore volume (Vtotal) of 1.411 cm3/g. The adsorption kinetics and thermodynamics of MO conformed to the pseudo-second-order kinetic model and Langmuir isotherm model, respectively. Based on the Langmuir fitting results, the theoretical maximum adsorption capacity (Qm) of MO adsorbed by BFAC-500 was calculated to be 591.71 mg/g at 318 K, pH=4.5, 0.4 g/L, with an equilibrium time of about 60 min. According to the thermodynamic calculation, the value of ΔH0 was less than 40 kJ/mol, which indicates that the adsorption mechanism was mainly based on physical adsorption, and based on the BET, Zeta potential, FTIR, and XPS before and after the adsorption, it was further known that it was mainly characterized by pore filling, electrostatic adsorption, hydrogen bonding, and π-π interactions. Moreover, when pH < pHzpc, the surface of BFAC-500 was positively charged and the adsorption of Cl-, SO42- and PO43- on MO had little effect; when pH>pHzpc, the surface was negatively charged and the adsorption of BFAC-500 on MO was enhanced by Na+, K+, and Mg2+. The BFAC materials in this study have promising applications in the practical removal of MO dyes.

Adsorptive removal of synthetic dye from its aqueous solution by using chitosan-bentonite composite: DFT and experimental studies

This research investigates the adsorption efficiency of a chitosan-bentonite (Ch–B) composite in removing methyl orange (MO), a common textile dye, from aqueous solutions. The study integrates experimental and theoretical analyses, employing density functional theory (DFT) to gain insights into the molecular interactions between the composite material and MO molecules. The Ch–B composite was characterized using various techniques, including FT-IR spectroscopy, XRD, and SEM–EDX. The experimental results indicate that the Ch–B composite exhibits a high adsorption capacity for MO, with optimal conditions identified for efficient removal. The Langmuir model was found to best fit the experimental data and the adsorption capacity was 117 mg g−1. Adsorption thermodynamics showed that the adsorption process was spontaneous, feasible, and exothermic. DFT calculation results are correlated with experimental findings to confirm theoretical predictions and improve the overall understanding of the adsorption process. Electronic structure calculations reveal the nature of the interactions between the Ch–B composite and MO molecules, including hydrogen bonds and electrostatic forces.

Magnetic Magnetite-Graphene Oxide (Fe3O4-GO) Nanocomposites for Removal of Dyes from Aqueous Solution

Magnetic magnetite-graphene oxide (Fe3O4-GO) was synthesized using an in-situ precipitation technique and applied in the adsorption of cationic rhodamine B (RhB) and anionic methyl orange (MO) dyes from aqueous solution. The nanocomposite was characterized by different techniques including FTIR, XRD, Raman, XPS, PPMS, BET, SEM and TEM techniques. Batch adsorption studies were conducted to investigate the effect of solution pH, initial metal ion concentration, adsorbent dosage and contact time. The synthesized Fe3O4-GO exhibited characteristic magnetic properties (saturation magnetization of 34 emu/g) and it separated from aqueous solution with ease through the application of an external magnetic field. The adsorption equilibrium time on the adsorption of RhB and MO onto Fe3O4-GO showed best removal of 99.12% for RhB after 60 min, while MO was removed efficiently after 120 min with a removal efficiency of 97.60%. The adsorption of the azo dyes followed the pseudo-second-order kinetics model with high correlation coefficients (0.99995) for RhB and (0.99925) for MO. Maximum removal of the dye pollutants by occurred at pH 8 for RhB and pH 4 for MO, while the optimal adsorbent dosage was 30 mg. The results showed that adsorption equilibrium data were fitted to Langmuir isotherm model and maximum monolayer adsorption capacities for RhB and MO at 70.64 and 15.94 mgg−1, respectively. The magnetic adsorbents were reused for a maximum of 7 cycles and showed reasonable stability and reproducibility. Furthermore, the results showed that Fe3O4-GO nanocomposite can be used as an effective material in the removal of dyes from wastewater.

Enhanced Adsorption of Methyl Orange from Aqueous Phase Using Chitosan-Palmer Amaranth Biochar Composite Microspheres.

To develop valuable applications for the invasive weed Palmer amaranth, we utilized it as a novel biochar source and explored its potential for methyl orange adsorption through the synthesis of chitosan-encapsulated Palmer amaranth biochar composite microspheres. Firstly, the prepared microspheres were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy and were demonstrated to have a surface area of 19.6 m2/g, a total pore volume of 0.0664 cm3/g and an average pore diameter of 10.6 nm. Then, the influences of pH, dosage and salt type and concentration on the adsorption efficiency were systematically investigated alongside the adsorption kinetics, isotherms, and thermodynamics. The results reveal that the highest adsorption capacity of methyl orange was obtained at pH 4.0. The adsorption process was well fitted by a pseudo-second-order kinetic model and the Langmuir isotherm model, and was spontaneous and endothermic. Through the Langmuir model, the maximal adsorption capacities of methyl orange were calculated as 495.0, 537.1 and 554.3 mg/g at 25.0, 35.0 and 45.0 °C, respectively. Subsequently, the adsorption mechanisms were elucidated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy investigations. It is indicated that electrostatic interactions, hydrogen bonding, π-π interactions and hydrophobic interactions between methyl orange and the composite microspheres were pivotal for the adsorption process. Finally, the regeneration studies demonstrated that after five adsorption-desorption cycles, the microspheres still maintained 93.6% of their initial adsorption capacity for methyl orange. This work not only presents a promising method for mitigating methyl orange pollution but also offers a sustainable approach to managing Palmer amaranth invasion.

Adsorption of anionic dyes from aqueous solutions by a novel CTAB/MXene/carbon nanotube composite: Characterization, experiments, and theoretical analysis

A novel three-dimensional composite was prepared by the self-assembly of MXene nanosheets and carbon nanotubes (CNTs) with the assistance of cetyltrimethylammonium bromide (CTAB), which was named as CMC composite. Adsorption of three anionic dyes, including Acid orange (AO7), Methyl orange (MO) and Congo red (CR), from aqueous solutions on the composite and the mechanisms were investigated in this study. Compared with MXene and CNTs, the CMC composite exhibited superior adsorption performance for AO7, MO and CR with maximum adsorption capacities of 367.9, 294.2, and 628.5 mg/g, respectively. The adsorption capacities of AO7 and MO on the CMC composite decreased, while that of CR increased with increasing temperatures. Quantum chemical calculations indicated that electrostatic interactions, π-π electron-donor-acceptor interactions and hydrogen bonding played important roles on the adsorption. The approximate site energy distribution analysis demonstrated that more adsorption active sites existed on the CMC composite than on MXene and CNTs, which endowed the CMC composite with higher adsorption capacities for these anionic dyes. The differences of adsorption behaviors for three anionic dyes could be ascribed to the number of available adsorption sites and the change of the site heterogeneity on the CMC surface.

Facile synthesis of lignin-based Fe-MOF for fast adsorption of methyl orange

To rapidly remove dyes from wastewater, iron-based metal–organic frameworks modified with phenolated lignin (NH2-MIL@L) were prepared by a one-step hydrothermal method. Analyses of the chemical structure and adsorption mechanism of the NH2-MIL@L proved the successful introduction of lignin and the enhancement of its adsorption sites. Compared with NH2-MIL-101-Fe without phenolated lignin, the modification with lignin increased the methyl orange (MO) adsorption rate of NH2-MIL@L. For the best adsorbent, NH2-MIL@L4, the MO adsorption efficiency in MO solution reached 95.09% within 5 min. NH2-MIL@L4 reached adsorption equilibrium within 90 min, exhibiting an MO adsorption capacity of 195.31 mg/g. The process followed pseudo-second-order kinetics and the Dubinin-Radushkevich model. MO adsorption efficiency of NH2-MIL@L4 was maintained at 89.87% after six adsorption-desorption cycles. In mixed solutions of MO and methylene blue (MB), NH2-MIL@L4 achieved an MO adsorption of 94.02% at 5 min and reached MO adsorption equilibrium within 15 min with an MO adsorption capacity of 438.6 mg/g, while the MB adsorption equilibrium was established at 90 min with an MB adsorption rate and capacity of 95.60% and 481.34 mg/g, respectively. NH2-MIL@L4 sustained its excellent adsorption efficiency after six adsorption-desorption cycles (91.2% for MO and 93.4% for MB). The process of MO adsorption by NH2-MIL@L4 followed the Temkin model and pseudo-second-order kinetics, while MB adsorption followed the Dubinin-Radushkevich model and pseudo-second-order kinetics. Electrostatic interactions, π-π interactions, hydrogen bonding, and synergistic interactions affected the MO adsorption process of NH2-MIL@L4.

Ferrocene crosslinked and functionalized chitosan microspheres towards bio-based Fenton-like system for the removal of organic pollutants

Dye-containing wastewater treatment has been a major long-term global challenge. For this purpose, a novel bio-based microspheres (CS-FC) with high specific surface area (63.24 m2·g−1) and nano-channels (17.95 nm) was prepared using chitosan as the framework and ferrocene as a crosslinking active group. CS-FC not only has the ability to rapidly enrich methyl orange (MO) through hydrogen-bonding and electrostatic attraction, but also almost completely degrades it in the presence of H2O2/K2S2O8 through a synergistic radical/non-radical mechanism under the activating effect of ferrocene. Without H2O2/K2S2O8, the maximum MO adsorption capacity of CS-FC is in the range 871–1050 mg·g−1, and conforms to a Langmuir isothermal model with pseudo-second-order kinetics. In the presence of H2O2/K2S2O8, the removal of MO dramatically increased from 32 % to nearly 100 % after incubation for 60 min, due to the simultaneous formation of highly reactive 1O2 and ·OH. The significant contribution from 1O2 endowed CS-FC/H2O2/K2S2O8 with high universality for degrading various organic pollutants (including azo dyes and antibiotics), a wide pH window (2–8), and low sensitivity to co-existing ions. Such cost-effective, recyclable porous bio-based microspheres are suitable for heterogeneous Fenton-like catalysis in organic wastewater treatment that rely on synergistic radical/non-radical reaction pathways.

Adsorptive removal of organic pollutants from aqueous solutions using novel GO/bentonite/MgFeAl-LTH nanocomposite

The contamination of water with organic pollutants such as dyes and phenols is a serious environmental problem, requiring effective treatment methods. In the present study, a novel nanocomposite was synthesized by intercalating graphene oxide and bentonite clay into MgFeAl-layered triple hydroxide (GO/BENT/LTH), which was characterized using different techniques. The adsorption efficacy of the GO/BENT/LTH nanocomposite was assessed via the removal of two harmful organic water pollutants, namely methyl orange (MO) and 2-nitrophenol (2NP). The obtained results revealed that the maximum adsorption capacities (qmax) of MO and 2NP reached 3106.3 and 2063.5 mg/g, respectively, demonstrating the excellent adsorption performance of the nanocomposite. Furthermore, this study examined the effects of contact time, initial MO and 2NP concentrations, pH, and temperature of the wastewater samples on the adsorptive removal of MO and 2NP by the GO/BENT/LTH nanocomposite. The pH, zeta potential, and FTIR investigations suggested the presence of more than one adsorption mechanism. Thermodynamic investigations elucidated the exothermic nature of the adsorption of MO and 2NP onto the GO/BENT/LTH nanocomposite, with MO adsorption being more sensitive to temperature change. Additionally, regeneration studies revealed a marginal loss in the MO and 2NP removal with the repetitive use of the GO/BENT/LTH nanocomposite, demonstrating its reusability. Overall, the findings of this study reveal the promise of the GO/BENT/LTH nanocomposite for effective water decontamination.

Adsorption of anionic and cationic azo dyes from wastewater using novel and effective multicomponent adsorbent

Water pollution is rising worldwide, necessitating innovative and effective treatment solutions. This study introduces a multicomponent/multifunctional novel nanocomposite synthesized from polyethyleneimine (PEI), graphene oxide (GO), bentonite clay, and MgFeAl-layered triple hydroxide (LTH), termed as AGO/Bentonite/LTH. In this study, the synthesized AGO/Bentonite/LTH nanocomposite was utilized to remove azo dyes (methyl orange and crystal violet) from contaminated water samples. The novel AGO/Bentonite/LTH nanocomposite was benchmarked against its pristine materials and their binary combinations. The results indicated the superior adsorption performance of the AGO/Bentonite/LTH nanocomposite relative to all other adsorbents synthesized and examined herein. All the synthesized adsorbents were characterized using different techniques in order to reveal their textural properties, functional groups, morphology, thermal stability, and crystallinity before applying them to decontaminate wastewater samples contaminated with methyl orange (MO) and crystal violet (CV). The Langmuir adsorption isotherm model predicted that the maximum adsorption capacities of CV and MO onto the AGO/Bentonite/LTH nanocomposite are 1705.1 and 1171.8 mg/g, respectively. On the other hand, zeta potential, pH, and FTIR studies suggested the existence of multiple mechanisms governing the adsorption of CV and MO onto the AGO/Bentonite/LTH nanocomposite. Thermodynamic results indicated the endothermicity and exothermicity of CV and MO adsorption, respectively. Another interesting finding reported herein is the high reusability of this nanocomposite as demonstrated by the minimal reduction in the removal of these two pollutants with the repetitive use of the nanocomposite. Additionally, the nanocomposite can also be easily and cheaply regenerated via a few rinses with a diluted NaOH aqueous solution. These interesting observations suggest that the synthesized AGO/Bentonite/LTH nanocomposite is a potent material for efficient dye removal from contaminated water bodies.

Preparation of cationic surfactant modified two-dimensional (2D) multi-layered Ti3C2Tx MXene for methyl orange removal from aqueous solution: Kinetic, equilibrium, and adsorption mechanisms

In this study, cetyltrimethylammonium bromide-modified multi-layered Ti3C2Tx MXene (CMM) was produced using a Ti3AlC2 precursor, and its capacity to remove the anionic dye, methyl orange (MO), was investigated in detail. An electrostatic combination between negatively charged Ti3C2Tx nanosheets and cationic surfactant solution (CTAB) produced this adsorbent. This triggered an exposure of the accessible active sites to further boost adsorption effectiveness by increasing the distance between the MXene nanosheets. Prepared adsorbents were characterized using some analytical techniques, including TGA, FESEM, EDX, FTIR, XRD, and N2 adsorption-desorption. Furthermore, some influencing parameters such as contact time, solution of pH, loading adsorbent, and initial dye concentration were evaluated, with findings showing that MO could adsorb CMM to its maximum capacity at an adsorbent dosage of 0.83 g/L, a contact time of 90 min, and a solution pH of 3. Adsorption results were found to be highly linked with both Langmuir isotherm (R2 = 0.9990) and the pseudo-second-order kinetic model (R2 = 0.9924). The maximum adsorption capacity of MO was obtained at approximately 213.00 mg/g. Also, hydrogen bonding, π-cation interactions, and electrostatic adsorption can all be implicated in the mechanism of MO adsorption on CMM. The fabricated CMM is presented as a prospective adsorbent for the removal of dyes from polluted water, demonstrating robust recyclability for up to the fifth iteration. All these outstanding properties indicate that cetyltrimethylammonium bromide-modified multi-layered Ti3C2Tx MXene can be considered as applicable adsorbents for textile pollutants.

Gemini Quaternary Ammonium Surfactants with Different Counterions-modified Montmorillonite for Efficient Removal of Methyl Orange.

Organic Na-montmorillonite (OMt-12-2-12·2Y - , Y=CH 3 CO 3 - , C 6 H 5 COO - and Br - ) modified by a series of Gemini quaternary ammonium surfactants with different counterions was prepared for enhancing the adsorption capacity of methyl orange. Compared with the initial adsorption capacity of 5.251 mg/g of Na-Mt, the adsorption effect of OMts under the optimal conditions increased by about 31~34 times. The adsorption isotherms and kinetics of all adsorption processes were respectively described by Langmuir and pseudo-second-order models. The structure, hydrophobicity and hydration of the counterions, as well as the affinity of the counterions with the long aliphatic chains, had a certain influence on the adsorption performance of OMts for methyl orange.

Selective separation of methylene blue from aqueous solution using Mn/Pd decorated chemically modified MoS2 nanocomposites

The presence of dyes in wastewater is posing as serious threat to human health. There are a huge number of physical, chemical, biological and hybrid methods available for the removal of colorants (dyes) from aqueous environment. In this work, we demonstrate the fabrication of new nanocomposites, MoS2-COOH/gly@M (M= Mn, Pd), with high adsorption property fabricated by chemically immobilizing manganese and palladium metallic centers onto the glycine- modified molybdenum disulfide (MoS2) material. The chemical and physical properties of adsorbents were analyzed using Fourier transform infrared spectrometer (FT-IR), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) companied by energy dispersive X-ray and mapping (EDAX & MAP) analyses. Zeta potential (ξ) technique was also used to measure the surface charge of adsorbents. Performances of nanocomposites were investigated on the sewage as adsorbent for dye removal. Synthesized nanocomposites revealed selective adsorption of methylene blue (MB) dye from aqueous mixture of MB and methyl orange (MO). Results displayed the equivalent high adsorption capacity for MB and MO up to 553 and 619 mg/g, respectively (green reaction condition= 120 min contact time, ,25 °C, pH 2.0 and pH 7.0, in the presence of 2 mg adsorbent and 50 mg/L (30 mL) initial concentration of MO and MB). The remarkable adsorption capacity of dye by MoS2-COOH/gly@M (M= Mn, Pd) nanocomposites can be attributed to the intermolecular interactions due to the presence of the amine, hydroxyl, and carboxyl functionalities. To describe the adsorption mechanism of MO and MB dye by synthesized nanomaterials, the pseudo-first-order and pseudo-second-order kinetics were further studied. Isotherm models displayed that the adsorption of MB and MO onto the MoS2-COOH/gly@M (M= Mn, Pd) nanocomposites is more correspondent with the Freundlich model with high-correlation coefficients. The results showed that the electrostatic attraction and H-bonding interaction were the basic cause of the adsorption of these anionic and cationic dyes on the surface of the nanocomposites. One of the distinguished properties of adsorbents is their capability to selectively adsorb MB from an admixture of MO and MB. The adsorption selectively has expanded in the following order: MoS2 < MoS2-COOH/gly@Mn < MoS2-COOH/gly@Pd. Based on the results, this new type of nanocomposites has potential to act as an effective and affordable adsorbent material for dye removal from an industrial sewage.