Removing Reactive Red 120 and 196 using chitosan/zeolite composite from aqueous solutions: Kinetics, isotherms, and process optimization

Electrospun nanofibers of polycaprolactone loaded with chitosan/carbon quantum dots composite for adsorptive removal of Cd(II) ions from wastewater: Adsorption, kinetics, thermodynamics, and BOX Behnken design

The research focused on assessing the improvements in stability and effectiveness regarding the elimination of Cd(II) ions. Specifically, this study involved the development of a novel electrospun nanofibrous membrane composed of chitosan (CS), carbon quantum dots (CQDs), and polycaprolactone (PCL). The membrane's primary application is the elimination of Cd(II) ions, from aqueous solutions. By precisely fine-tuning the electrospinning process parameters, we succeeded in optimizing the membrane. The characterizations performed using FTIR, XRD, XPS, SEM and EDX confirm the successful formation of a robustly crosslinked CS/CQDs/PCL nanofiber membrane. This thorough investigation not only showcases the material's textural characteristics but also underscores its potential for various applications. The examination further analyzed the influence of numerous factors, such as dosage, pH, temperature, and initial concentration, by the adsorption mechanism. The research incorporated equilibrium assessments in conjunction with kinetic evaluations to evaluate the characteristics of adsorption. The results showed that the Langmuir isotherm model well captured the adsorption process and that it complied with pseudo-second-order kinetics values. The fact that metal adsorption rises with temperature indicates that endothermic reactions and spontaneous behavior are both features of the adsorption process. The data suggests that the most effective situations for the elimination of Cd(II) ions in water purification are characterized by a pH level of 6, a amount of 0.02 g of CS/CQDs/PCL per 25 mL, and an adsorption capability measured at 340.05 mg/g precisely for the Cd(II) ions solution. In order to enhance the efficiency of the adsorbent in Cd(II) ions elimination from water, it is crucial to consider multiple significant factors. Systematic trials using the Box-Behnken design and response surface methods, made possible by the Design-Expert software, demonstrated significant improvements in the adsorption efficiency. A thorough assessment of the adsorbent's reusability conducted over five consecutive adsorption and desorption cycles shows a high degree of consistency in its removal efficacy.

Smart nanocomposite of carbon quantum dots in double hydrogel (carboxymethyl cellulose/chitosan) for effectively adsorb and remove diquat herbicide: Characterization, thermodynamics, isotherms, kinetics, and optimizing through Box-Behnken Design

This research synthesized carbon quantum dots (CQDs) encapsulated in a chitosan (CS) and carboxymethyl cellulose (CMC) matrix. The crosslinking with epichlorohydrin formed (CQDs-CS/CMC) hydrogel beads for effective removal of diquat (DQ) herbicides. Various techniques like XRD, FT-IR, FESEM, EDX, XPS, and nitrogen adsorption/desorption isotherm analysis were used to evaluate the textural properties. The textural properties of the CQDs-CS/CMC were investigated through nitrogen adsorption/desorption isotherms. The surface area was found to be 95.72 m2/g, pore size 6.57 nm, and pore volume 0.313 cc/g. Post-DQ adsorption, these values decreased to 68.44 m2/g, 4.2 nm, and 0.162 cc/g, indicating DQ blocked mesopores and adsorption sites. The study also examined the effects of dosage, pH, temperature, and initial DQ concentration on adsorption, employing equilibrium and kinetic studies. The system conformed to pseudo-second-order kinetics and Langmuir isotherm models. Chemisorption was the main adsorption process, with an energy of 32.3 kJ/mol. Increased metal uptake at higher temperatures shows the process is spontaneous and endothermic. The Box-Behnken Design software identified optimal adsorption parameters: a pH of 8 and a dosage of 0.02 g of CQDs-CS/CMC per 25 mL of DQ solution, achieving 449.6 mg/g adsorption capability. Extensive testing using Design-Expert software substantially improved the adsorption procedure. The assessment of adsorbent stability involved six cycles of adsorption/desorption. Results showed consistent reusability with no significant reduction in removal efficacy. It maintained its initial chemical configuration before and after repurposing, exhibited consistent performance, and reliable XRD results.

Effective of mercury (II) removal from contaminated water using an innovative nanofiber membrane: Kinetics, isotherms, and optimization studies

The study aimed to evaluate enhancements in both stability and efficiency concerning the removal of Hg(II) ions. This research specifically concentrated on creating an innovative electrospun nanofibrous membrane (CPP) that is made up of chitosan (CS), polyethylenimine (PEI), and polycaprolactone (PCL). The membrane's primary purpose is to enhance the elimination of Hg(II) from aqueous solutions. By carefully adjusting the electrospinning process variables, we improved its efficiency. Characterization techniques like FTIR, XRD, XPS, SEM, and EDX confirm the successful creation of a highly crosslinked CPP nanofiber membrane. This detailed examination reveals the textural attributes of the material, concurrently underlining its relevance in various domains. The investigation additionally delves into the impact of several aspects on the adsorption mechanism, comprising dosage, pH levels, temperature, and initial Hg(II) concentration. The research incorporates an analysis of adsorption characteristics by integrating kinetic evaluations with equilibrium studies. The findings indicate that the adsorption mechanism aligns with the values of pseudo-second-order kinetics and is appropriately represented by the Langmuir isotherm model. Furthermore, the data suggest a hybrid nature of the adsorption procedure, exhibiting both spontaneous and endothermic characteristics, as showed by the increased metal adsorption at elevated temperatures. The analysis reveals that optimal conditions for the elimination of Hg(II) ions in water purification involve a pH of 6 and the use of 0.02 g of CPP per 25 mL of solution, corresponding to a projected adsorption capability of 393.043 mg/g precisely for the Hg(II) ions solution. To enhance the efficacy of the adsorbent in the elimination of Hg(II) ions from water, several key parameters require careful examination. Notable advancements in adsorption performance have been achieved through the application of response surface methodologies and structured experimentation utilizing the Box-Behnken design, facilitated by the Design-Expert software. A thorough evaluation of the reusability of the adsorbent, conducted during five consecutive cycles of adsorption and desorption, shows a remarkable stability in its ability to efficiently remove Hg(II) ions.

Fabrication of Cerium Metal-Organic Frameworks Functionalized with Glutamic Acid for Adsorption of Basic Red 46 from Aqueous Solutions: Kinetics, Thermodynamics, and Optimization

This research investigated the efficient removal of cationic Basic red 46 (BR46) dye from aqueous solutions, by means of cerium metal-organic frameworks (Ce-MOF) functionalized with glutamic acid to create NH2-Ce-MOF. The NH2-Ce-MOF was easily produced through a postsynthesis functionalization strategy and extensively analyzed through numerous methods with X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray (EDX), and N2 adsorption/desorption isotherm. The findings revealed that the synthesized adsorbent had a high surface area of 1158.8 m2/g, a pore size of 1.511 nm, and a pore volume of 0.875 cm3/g. Upon adsorption of the BR46 dye, the surface area decreased to 872.6 m2/g, the pore size reduced to 1.18 nm, and the pore volume released to 0.53 cm3/g. The decreases in surface area, pore size, and volume demonstrate the material's strong ability to adsorb substances, as the dye molecules can fill the tiny pores. They exhibited an increased adsorption capability of 454.8 mg/g. The Langmuir isotherm and pseudo-second-order kinetic models performed the best at simulating adsorption isotherm and kinetic curves, respectively. The exhibition of chemisorption and adsorption energy of 28.4 kJ/mol was supported by various adsorption driving forces, including hydrogen bonding, electrostatic interaction, π-π conjugation, pore filling, and van der Waals force. After conducting thorough research on the impact of temperature, it was established that the adsorption procedure is both endothermic, indicated by a positive ΔH° of 83.7 kJ/mol.K, and spontaneous, as confirmed by the increase in negativity of ΔG° with rising temperatures. Additionally, the increase in randomness with increasing temperatures is evident in the ΔS° value of 289.32 J/mol. Employed Box-Behnken design (BBD) and response surface methodology (RSM) to enhance the results of the adsorption procedure. The NH2-Ce-MOF proposal is a practical, affordable solution for eliminating BR46 dye from wastewater streams because the adsorbent was composed of reusable materials and reused over five times with excellent efficiency.

Synthesis of pomegranate peel-activated carbon encapsulated onto carboxymethylcellulose and polyethylenimine for cadmium (II) adsorption: Optimization, kinetics and isotherm modeling

This research explores pomegranate peel as a precursor for activated carbon to eliminate cadmium (II) ions from aqueous solutions. The produced activated carbon was encapsulated with carboxymethylcellulose and polyethylenimine, then crosslinked with epichlorohydrin to form activated carbon carboxymethylcellulose and polyethyleneimine (ACCP) hydrogel beads. Numerous analytical methods were working to characterize the adsorbent, including X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), and nitrogen adsorption/desorption isotherms. The BET analysis revealed a surface area of 110.02 m2/g, indicating a highly porous material with numerous active adsorption sites. A pore volume of 0.13 cc/g shows significant capacity for retaining adsorbed ions. The average pore radius of 1.88 nm classifies as mesopores, typically found near the transition between micropores and mesopores. Examine the influence of various factors, including pH, concentration of Cd(II), amount of adsorbent, duration of contact, and temperature, on the adsorption process. The adsorption isotherm monitored the Langmuir equation, suggesting a specific adsorption procedure. Kinetics were defined by the pseudo-second-order model, linking the adsorption rate to the square of unoccupied sites. Thermodynamic parameters yielded ΔHo of 97.94 kJ/mol and ΔSo of 334.8 J/mol.K, indicating an endothermic and spontaneous adsorption process. Various mechanisms for Cd(II) interaction with ACCP may include ion exchange, electrostatic forces, or complexation. Data indicate that optimal parameters for efficient Cd(II) removal in water are a pH of 6, 0.02 g of ACCP per 25 mL solution, and an adsorption capacity of 301.6 mg/g. To enhance the adsorbent's efficacy, various influential parameters must be thoroughly examined. A Box-Behnken design (BBD) and response surface methodology (RSM) are used to help identify the ideal conditions for Cd(II) adsorption. An investigation of the adsorbent's reusability over five cycles shows a substantial reliability for removal applications.

Adsorption and eliminating of diquat herbicide using layer double hydroxide enclosed in double layer hydrogel beads of carboxymethyl cellulose and alginate: Synthesis, characterization, adsorption isotherm, kinetics, thermodynamics and optimization via box-behnken design

This study involved the creation of AlCu-layered double hydroxide (LDH) encapsulated in carboxymethyl cellulose (CMC) and alginate (Alg), which was then crosslinked with epichlorohydrin to form hydrogel beads (AlCu-LDH/CMC-Alg hydrogel beads) used for the removal of diquat (DQ) herbicide. The resulting material, AlCu-LDH/CMC-Alg hydrogel beads, underwent a comprehensive analysis of its properties using XRD, FT-IR, XPS, EDX, N2 adsorption/desorption isotherm, and FESEM to determine its textural characteristics. The AlCu-LDH/CMC-Alg hydrogel beads was analyzed using nitrogen adsorption/desorption isotherms to assess its textural properties. The hydrogel beads of AlCu-LDH/CMC-Alg showed a surface area of 114.22 m2/g, a pore volume of 0.35 cc/g, and a pore radius of 3.62 nm, indicating a mesoporous structure with a notable adsorption capacity. Following the adsorption of DQ, these measurements decreased to 65.145 m2/g, 0.2 cc/g, and 2.4 nm, respectively, suggesting that the DQ had filled or blocked the pores. This study also analyzed the impact of dose, pH, temperature, and initial concentration on the adsorption process. Equilibrium and adsorption kinetics were used to examine the adsorption characteristics. The process followed the pseudo-second-order and Langmuir isotherm models. The primary adsorption mechanism identified was chemisorption, with an adsorption energy of 29.6 kJ.mol-1. The rise in DQ absorption at higher temperatures suggests an endothermic and spontaneous adsorption process. The optimal adsorption parameters, as determined by the Box-Behnken design software, are a pH of 8, a dosage of 0.02 g of AlCu-LDH/CMC-Alg hydrogel beads per 25 mL, and an adsorption capacity of 302.6 mg/g for the DQ solution. Through careful testing and utilization of the Box-Behnken design and response surface technique in the Design-Expert software, significant enhancements were made to the adsorption process. The stability of the adsorbent was assessed by conducting six successive cycles of adsorption and desorption, revealing that its reusability remained steady with no noticeable decline in removal efficiency. Furthermore, it preserved its original chemical makeup both before and after being reused, demonstrated steady effectiveness, and kept consistent X-ray diffraction (XRD) results.

Elimination of Ni(II) from wastewater using metal-organic frameworks and activated algae encapsulated in chitosan/carboxymethyl cellulose hydrogel beads: Adsorption isotherm, kinetic, and optimizing via Box-Behnken design optimization

The study investigated the enhancement of stability and efficacy in the removal of bivalent nickel ions (Ni(II)) by utilizing a cerium metal-organic framework (Ce-MOF) encapsulated within a food-grade algal matrix. This composite material is integrated into a dual-layer hydrogel containing chitosan and carboxymethyl cellulose. The enhancement of structural integrity in the final product can be attributed to the cross-linking process with epichlorohydrin, leading to the development of Ce-MOF-FGA/CMC-CS hydrogel beads. A comprehensive characterization of the adsorbent was conducted utilizing various analytical methods. These included X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDX), nitrogen adsorption/desorption isotherm analysis, and field emission scanning electron microscopy (FESEM), all aimed at clarifying the textural characteristics of the material. The investigation also explored the effects of multiple variables, including dosage, pH, temperature, and initial concentration, on the adsorption process. The study conducted equilibrium analyses alongside kinetic evaluations to assess the adsorption characteristics. The results demonstrated that the adsorption behavior aligned with the principles of pseudo-second-order kinetics and was suitably described by the Langmuir isotherm model. The data showing heightened metal adsorption as temperatures increase suggests that the adsorption process is characterized by both endothermic properties and spontaneity. In order to determine the most favorable conditions for adsorption, the Box-Behnken design software was utilized. The findings indicate that the optimal conditions include a pH of 5, a dosage of 0.02 g of Ce-MOF-FGA/CMC-CS hydrogel beads for every 25 mL of solution, and an adsorption capacity of 301.05 mg/g specifically for the Ni(II) solution. To optimize the performance of the adsorbent in the removal of Ni(II) during water purification, it is essential to take into account several key variables. The adsorption efficiency was significantly improved by conducting a series of methodically planned experiments, employing the Box-Behnken design alongside response surface methodology, as supported by Design-Expert software. An in-depth evaluation of the adsorbent's reusability carried out over six successive cycles of adsorption and desorption, indicates a significant stability in its removal efficiency.

Electrospun nanofiber chitosan/polyvinyl alcohol loaded with metal organic framework nanofiber for efficient adsorption and removal of industrial dyes from waste water: Adsorption isotherm, kinetic, thermodynamic, and optimization via Box-Behnken design

Dyes can seriously harm human health because they linger or break down in the environment and find their way into drinking water through the water cycle. Examples of the most important interactions between MOFs and dyes are provided, and an effort is made to comprehend how surface charge and size compatibility affect the adsorption process. The methods for incorporating functionalized Ce-MOF into electrospun nanofibers made of polyvinyl alcohol and chitosan to create functionalized cerium metal organic framework nanofiber membranes (FCCP nanofiber membranes) are presented in this paper. A number of techniques, including XRD, FT-IR, N2 adsorption/desorption isotherm, SEM mapping, and EDX, were used to successfully manufacture and analyze the adsorbent. Examine the effects of pH, adsorbent dose, starting concentration, contact time, and thermodynamics on the adsorption process of malachite green dye (MG) onto FCCP nanofiber membrane. The Langmuir and pseudo-second-order adsorption processes were fitted. The adsorption process was chemisorption, as shown by the adsorption energy of 31.6 kJ/mol. Examine the adsorption mechanism, which may involve electrostatic interaction, pore filling, and π-π interaction. The increase in MG dye absorption at higher temperatures suggests an endothermic and spontaneous adsorption process. For the MG dye solution, the ideal adsorption parameters were determined using the Box-Behnken design software to be pH 8, a dosage of 0.2 g of FCCP nanofiber membrane per 25 mL, and an adsorption capacity of 359.2 mg/g. These elements are necessary for the composite sponge to be utilized in water purification processes and to be the most successful at adsorbing arsenate. Applying the Box-Behnken design and response surface approach features of the Design-Expert software successfully enhanced the adsorption process with a small number of planned tests. The stability of the adsorbent was confirmed by an investigation of its reusability using six consecutive cycles of adsorption and desorption, which revealed no appreciable drop in removal effectiveness. It also demonstrated consistent efficiency, preserved homogeneous XRD data, and kept its original chemical composition both before and after reuse.

Kinetic and isotherm studies of cr (VI) adsorption from aqueous media by using a synthetic chitosan-allophane nanocomposite

This study investigates Cr (VI) removal from an aqueous solution by a synthetic chitosan-allophane nanocomposite. The nanocomposite was synthesized using the solvothermal method. The adsorbent was characterized utilizing X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) images, and the Brunauer-Emmet-Teller (BET) method. This work investigated the influence of the solid/liquid ratio, pH, contact time, and initial concentration on the adsorption process, as well as the adsorption kinetics and isotherms. The maximum adsorption capacity of the synthetic nanocomposite for Cr (VI) is 112.17 (mg/g) under optimum conditions. The kinetics study shows that the pseudo-second-order kinetic equation better describes the adsorption behavior of the adsorbent. The isotherms study suggests that the adsorption process of the synthetic chitosan-allophane nanocomposite follows the Langmuir model. Freundlich isotherm shows a better fit to the process with R2 = 0.97 and Freundlich constant of 42.9 L/g. The adsorption of Cr (VI) ions on adsorbent well fits to pseudo-second-order with qe: 125 mg/g. Moreover, the stability and reproducibility of the synthetic nanocomposite were investigated. This study presents a approach for synthesizing high surface area, engineered morphology, reusable, and stable nanocomposite for effectively adsorbing heavy metal ions from wastewaters.

Electrospun nanofibers membrane of carbon quantum dots loaded onto chitosan-polyvinyl alcohol for removal of rhodamine B dye from aqueous solutions: Adsorption isotherm, kinetics, thermodynamics and optimization via Box-Behnken design

The study aims to blend carbon quantum dots (CQDs) with chitosan and polyvinyl alcohol to produce micro fibrous membranes. To create electrospun carbon quantum dots nanofibers (ECQNF) that can absorb rhodamine B dye (RB) found in wastewater. A variety of methodologies were utilized to investigate the ECQNF, including scanning electron microscopy (SEM) for surface morphology, Fourier transform infrared spectroscopy (FTIR) to identify functional groups, X-ray photoelectron spectroscopy (XPS) for elemental analysis, X-ray diffraction (XRD), and N2 adsorption/desorption isotherms for structural analysis. Batch adsorption experiments varied parameters like contact time, initial RB concentrations, and adsorbent dosages. The membrane achieved a maximum adsorption of 522 mg/g at 600 ppm and 298 K. Thermodynamic evaluation indicated the process is endothermic. Several isothermal models analyzed the adsorption of RB onto the electrospun adsorbent, with the Langmuir model best fitting the data. The pseudo-second-order model effectively described the kinetics. The Dubinin-Radushkevich model indicated an adsorption energy of 32.6 kJ/mol, suggesting chemisorption. Positive entropy and enthalpy values, along with a more negative Gibbs free energy, confirm the process is endothermic and spontaneous. The increase in adsorption capability with rising temperature is evident. The ECQNF can be reused up to six times, maintaining efficiency and chemical structure. The XRD analyses demonstrate consistent results before and after each reuse cycle. It's crucial to investigate the interaction mechanisms between the adsorbent and adsorbate, including hydrogen bonding, n-π stacking, electrostatic interactions, and pore filling. Using the Box-Behnken design, the adsorption outcomes were optimized, highlighting the effectiveness of ECQNF in enhancing pollutant removal from wastewater.

Efficient removal of tetracycline by VCo-layered double hydroxide encapsulated with chitosan: Optimization via Box-Behnken design, and thermodynamics

The VCo-LDH/CS hydrogel beads were created by combining VCo-layered double hydroxide (VCo-LDH) and chitosan (CS) using a cross-linking process with epichlorohydrin. These beads were specifically designed to remove tetracycline (TTC). To characterize the VCo-LDH/CS hydrogel beads, several analytical techniques were used, with PXRD, XPS, FESEM, EDX, and FT-IR. The thorough characterization methods provided crucial information about the phase, crystallinity, morphology, surface properties, and chemical arrangement of the synthesized VCo-LDH/CS hydrogel beads. However, significant changes occurred in these important physical properties after TTC was adsorbed. These alterations in the physical characteristics of the VCo-LDH/CS hydrogel beads indicate that the TTC molecules have been successfully absorbed into the porous assembly of the adsorbent, filling the obtainable adsorption places and causing a decrease in the material's overall surface area, pore size, and pore volume. It was determined that a pH of 7 and an applied dosage of 0.02 g/25 mL were the most favorable conditions for achieving the highest adsorption capability of 546.6 mg/g. The Langmuir equation accurately represented the adsorption isotherm, and the kinetic information were evaluated using the pseudo-second-order model. Chemisorption was utilized for the adsorption procedure, demonstrated by an adsorption energy of 29.62 kJ/mol. Analysis of thermodynamic limits ΔG°, ΔH°, and ΔS° suggested that the adsorption procedure happened spontaneously, maintained by the progressively negative ΔG° as enthalpy and entropy values increased. This demonstrates the complex and changing nature of the adsorption procedure, with various potential mechanisms suggested to affect it, including π-π interactions, electrostatic forces, pore filling, and hydrogen bonding. The utilization of a Box-Behnken design (BBD) alongside Response Surface Methodology (RSM) enhanced the outcomes of the adsorption process.

Use of polysulfone capsules impregnated with phosphonium-based ionic liquid for removal of black reactive dye

In this study, polysulfone capsules impregnated with the ionic liquid tetradecyltrihexylphosphonium decanoate (IC) were synthesized and applied to remove the reactive dye black (RB) an aqueous solution. The impregnated capsules were characterized by scanning electron microscopy (SEM), surface analysis by Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). Some adsorption parameters were investigated, such as the effect of adsorbent dosage (0.01-1.5 g/30 mL), pH (2-12), and temperature (293-323 K). At pH 8, the dye was completely removed and the process was characterized as exothermic. The kinetic model that best represented the adsorption of RB was the pseudo-first-order. The analysis of the variation of the dye concentration (150-1000 mg L-1) was performed and the Langmuir, Freundlich, and Redlich-Peterson models were presented in their nonlinear form. The maximum adsorption capacity identified by the Langmuir model was q max of 276.94 mg g-1, and the capsules could be reused for up to 4 cycles, showing removal percentages above 50% and cumulative loading of 520.8 mg g-1. In addition, a fixed bed column adsorption study was carried out. These results indicate that the proposed material has a high adsorptive capacity and has potential for application in the treatment of industrial textile effluents containing reactive dyes. In addition to considerably reducing the toxic effects of the dye on Lactuca sativa, when compared with pure IL.

Adsorption and removal of Pb (II) via layer double hydroxide encapsulated with chitosan; synthesis, characterization adsorption isotherms, kinetics, thermodynamics, & optimization via Box-Behnken design

The study aimed to enhance the stability and efficiency of removing bivalent Pb(II) by encapsulating AlNi-layered double hydroxide (LDH) in chitosan and itaconic acid to create an adsorbent with chemically active sites. The resulting material, AlNi-LDH/CS, underwent thorough property analysis using XRD, FT-IR, XPS, EDX, N2 adsorption/desorption isotherm, and FESEM to find out what textural characteristics it has. Specifically, nitrogen adsorption/desorption isotherms were utilized to assess the textural properties of AlNi-LDH/CS. The Al/Ni-LDH/CS surface displayed a specific surface area of 71.95 m2/g and an average pore size of 2.537 nm, consistent with the platelets' external surface. The effects of dose, pH, temperature, and starting concentration on the adsorption process were also investigated in this study. The adsorption characteristics have been examined by means of equilibrium and adsorption kinetics. The adsorption process adhered to the pseudo-second-order and Langmuir isotherm models. The predominant adsorption process was found to be chemisorption, which had an adsorption energy of 28.42 kJ·mol-1. An endothermic and spontaneous adsorption process is suggested by the increase in metal absorption at increasing temperatures. The Box-Behnken design software was utilized to establish the optimal adsorption parameters as pH 5, a dosage of 0.2 g of AlNi-LDH/CS per 25 mL, and an adsorption capacity of 453.05 mg/g for the Pb(II) arsenate solution. For the composite sponge to be most effective in adsorbing arsenate and be used in water purification procedures, these factors are essential. The adsorption process was successfully improved with few planned tests by applying the Box-Behnken design and response surface technique aspects of the Design-Expert software. An evaluation of the adsorbent's reusability using six successive cycles of adsorption and desorption confirmed its stability and showed no discernible decrease in removal efficiency. Additionally, it retained its original chemical composition before and after reuse, showcased consistent efficiency, and maintained uniform XRD data.

Zeolites in wastewater treatment: A comprehensive review on scientometric analysis, adsorption mechanisms, and future prospects

Zeolites possess a microporous crystalline structure, a large surface area, and a uniform pore size. Natural or synthetic zeolites are commonly utilized for adsorbing organic and inorganic compounds from wastewater because of their unique physicochemical properties and cost-effectiveness. The present review work comprehensively revealed the application of zeolites in removing a diverse range of wastewater contaminates, such as dyes, heavy metal ions, and phenolic compounds, within the framework of contemporary research. The present review work offers a summary of the existing literature about the chemical composition of zeolites and their synthesis by different methods. Subsequently, the article provides a wide range of factors to examine the adsorption mechanisms of both inorganic and organic pollutants using natural zeolites and modified zeolites. This review explores the different mechanisms through which zeolites effectively eliminate pollutants from aquatic matrices. Additionally, this review explores that the Langmuir and pseudo-second-order models are the predominant models used in investigating isothermal and kinetic adsorption and also evaluates the research gap on zeolite through scientometric analysis. The prospective efficacy of zeolite materials in future wastewater treatment may be assessed by a comparative analysis of their capacity to adsorb toxic inorganic and organic contaminates from wastewater, with other adsorbents.

Kinetics and thermodynamics investigations of efficient and eco-friendly removal of alizarin red S from water via acid-activated Dalbergia sissoo leaf powder and its magnetic iron oxide nanocomposite

The present work aimed to highlight an efficient, readily accessible, and cost-effective adsorbent derived from Dalbergia sissoo (DS) leaf powder for removing the environmentally hazardous dye "alizarin red S" (ARS) from hydrous medium. A variant of the adsorbent is activated via sulfuric acid and composited with magnetic iron oxide nanoparticles (DSMNC). Both adsorbents are thoroughly characterized using techniques such as Fourier transform infrared spectroscopy, point of zero charge, energy-dispersive X-ray spectroscopy, and scanning electron microscopy, which show that they have a porous structure rich in active sites. Different adsorption conditions are optimized with the maximum removal efficiency of 76.63% for DS and 97.89% for DSMNC. The study was highlighted via the application of various adsorption isotherms, including Freundlich, Langmuir, Temkin, and Dubinin-Radushkevich, to adsorption data. Pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were utilized to investigate the kinetics and mechanism of adsorption. The Freundlich model and pseudo-second-order kinetics exhibited the best fit, suggesting a combination of physical interactions, as confirmed by the D-R and Temkin models. The dominant adsorbate-adsorbent interactive interactions responsible for ARS removal were hydrogen bonding, dispersion forces, and noncovalent aromatic ring adsorbent pi-interactions. Thermodynamic parameters extracted from adsorption data indicated that the removal of the mutagenic dye "ARS" was exothermic and spontaneous on both DS and DSMNC, with DSMNC exhibiting higher removal efficiency.

Novel algae-chitosan/alginate beads for efficient basic Fuchsin removal: Synthesis, characterization, adsorption study, mechanism, and optimization

In this study, utilized algae activated with citric acid and lime juice to develop a novel bioadsorbent, The Algae@CS/Alginate beads were formed by encapsulating the activated algae with chitosan and alginate, producing a nanocomposite that is efficient in removing Basic Fuchsin (BF) dye from water. The beads were characterized by means of a diversity of techniques, such as FTIR, XRD, XPS, SEM and determination the surface area via N2 adsorption/desorption isotherm that permitted that the adsorbent has high surface area 124.43 m2/g. The electrical properties of the BF, including its structure and reactivity, were determined by density functional theory (DFT). The MEP data and the molecular orbitals (HOMO and LUMO), as well as the sites of the electrophilic besides nucleophilic attack places, correspond fairly well, according to DFT. The adsorption process was fitted to Langmuir isothermally, and kinetically to pseudo-second-order (PSOE) model. The adsorption mechanism was identified as chemisorption with an adsorption energy of 32.6 kJ/mol. Thermodynamic research shows that the BF adsorption process by Algae@CS/Alginate beads is spontaneous and endothermic because of the positive ΔHo and negative ΔGo. Through numerical optimization of the programmed, the ideal conditions for adsorption were strongminded to be a pH of 8, a dosage of 0.02 g/25 mL for Algae@CS/Alginate beads, and a concentration of 367.27 mg/g of BF. Using the least amount of intended experiments, the adsorption procedure was optimized by the request of Box-Behnken design (BBD) and answer surface methodology (RSM) in Design-Expert software. Adsorbent reusability test results showed that, following eight successive cycles of adsorption and desorption, the adsorbent was stable and that removal efficacy had not decreased. It additionally demonstrated good efficacy, no alteration in chemical conformation, and the same XRD and FTIR data before and after recycle. Analyze the interaction between the Algae@CS/Alginate beads and the BF.

Removal of organic and inorganic effluents from wastewater by using degradation and adsorption properties of transition metal-doped nickel ferrite

Removal of water pollutants (methylene blue dye and heavy metals) was achieved by zinc/manganese-doped nickel ferrites (Ni1 - xMxFe2O4, where x = 0.00, 0.025, 0.10). Degradation of dye was achieved under natural solar light illumination. Degradation studies of dye were conducted under different parameters such as contact time-80 min, dye's concentration-5 mg/L, pH-7, and dosage of ferrites-15 mg. The adsorption of dye was studied using non-linear kinetics models (pseudo-first-order and pseudo-second-order) and isotherm models (Langmuir and Freundlich). The adsorption of dye followed pseudo-first-order kinetics (R2 = 0.99377) than second-order kinetics (R2 = 0.98063) and Langmuir isotherm model (R2 = 0.96095) than Freundlich model (R2 = 0.95962) with maximum adsorption efficiency of 29.62 mg/g. Doping of nickel ferrites caused an increase in the removal percentage of methylene blue dye (80 to 90%) and inorganic effluents (75 to 95% for lead and 47 to 82% for cadmium). In addition to this, band gap energy (2.43 to 3.26 eV) (UV-Vis spectroscopy), pore radius (65.2 to 74.8 A°), and specific surface area (16.45 to 27.95 m2/g) (BET analysis) were also increased. Generally, the results of the study revealed that synthesized nanoparticles can act as potential candidate for the removal of effluents from wastewater under optimum parameters along with recyclability, reusability, and separation under the influence of a magnetic field.

pH-dependent and whole-cell catalytic decolorization of dyes using recombinant dye-decolorizing peroxidase from Rhodococcus jostii

Dyes in wastewater have adverse effects on the environment and human health. Dye-decolorizing peroxidase (DyP) is a promising biocatalyst to dyes degradation, but the decolorization rates varied greatly which influencing factors and mechanisms remain to be fully disclosed. To explore an effective decolorizing approach, we have studied a DyP from Rhodococcus jostii (RhDyPB) which was overexpressed in Escherichia coli to decolorize four kinds of dyes, Reactive blue 19, Eosin Y, Indigo carmine, and Malachite green. We found the decolorization rates of the dyes by purified RhDyPB were all pH-dependent and the highest one was 94.4% of Malachite green at pH 6.0. ESI-MS analysis of intermediates in the decolorization process of Reactive blue 19 proved the degradation was due to peroxidase catalysis. Molecular docking predicated the interaction of RhDyPB with dyes, and a radical transfer reaction. In addition, we performed decolorization of dyes with whole E. coli cell with and without expressing RhDyPB. It was found that decolorization of dyes by E. coli cell was due to both cell absorption and degradation, and RhDyPB expression improved the degradation rates towards Reactive blue 19, Indigo carmine and Malachite green. The effective decolorization of Malachite green and the successful application of whole DyP-overexpressed cells in dye decolorization is conducive to the bioremediation of dye-containing wastewaters by DyPs.

Nylon fiber waste as a prominent adsorbent for Congo red dye removal

In this research nylon fibers wastes (NF) were fabricated into porous sheet using a phase inversion technique to be utilized as an adsorbent materials for Congo red dye (CR). The fabricated sheet denoted as NS was characterized using FTIR and XRD. The surface studies of the adsorbent materials using SEM and BET analysis reveals a highly pores structure with an average pore volume 0.61 cc/g and BET surface area of 767 m2/g. The adsorption studies of fabricated NS were employed into CR at different parameters as pH, effect of time and dye concentration. The adsorption isotherm and kinetic studies were more fit to Langmuir and pseudo second order models. The maximum adsorption capacity qmax reached 188 mg/g with removal percentage of 95 for CR concentration of 400 mg/L at pH 6 and 0.025 g NS dose for 10 ml CR solution. The regeneration study reveals a prominent adsorption behavior of NS with removal % of 88.6 for CR (300 mg/L) after four adsorption desorption cycles. Effect of incorporation of NaonFil Clay to NS was studied using Response Surface Methodology (RSM) modeling and reveals that 98.4% removal of CR could be achieved by using 19.35% wt. of fiber with 8.2 g/L dose and zero clay, thus at a predetermined parameters studies of NanoFil clay embedded into NS, there are no significant effect for %R for CR.

Current and Expected Trends for the Marine Chitin/Chitosan and Collagen Value Chains

Chitin/chitosan and collagen are two of the most important bioactive compounds, with applications in the pharmaceutical, veterinary, nutraceutical, cosmetic, biomaterials, and other industries. When extracted from non-edible parts of fish and shellfish, by-catches, and invasive species, their use contributes to a more sustainable and circular economy. The present article reviews the scientific knowledge and publication trends along the marine chitin/chitosan and collagen value chains and assesses how researchers, industry players, and end-users can bridge the gap between scientific understanding and industrial applications. Overall, research on chitin/chitosan remains focused on the compound itself rather than its market applications. Still, chitin/chitosan use is expected to increase in food and biomedical applications, while that of collagen is expected to increase in biomedical, cosmetic, pharmaceutical, and nutritional applications. Sustainable practices, such as the reuse of waste materials, contribute to strengthen both value chains; the identified weaknesses include the lack of studies considering market trends, social sustainability, and profitability, as well as insufficient examination of intellectual property rights. Government regulations, market demand, consumer preferences, technological advancements, environmental challenges, and legal frameworks play significant roles in shaping both value chains. Addressing these factors is crucial for seizing opportunities, fostering sustainability, complying with regulations, and maintaining competitiveness in these constantly evolving value chains.

Cross-linked chitosan-epichlorohydrin/bentonite composite for reactive orange 16 dye removal: Experimental study and molecular dynamic simulation

Chitosan/bentonite beads (CsB) composites were prepared from chitosan (Cs) and bentonite (B) and cross-linked with epichlorohydrin for removal of reactive orange 16 (RO16) and methylene blue (MB). The adsorption results have shown that the (Cs20B80), 20 % wt of (Cs) and 80 % (B), was selected as the best adsorbent for (MB) and (RO16) dyes. SEM, EDX, FTIR, BET, and pHpzc were implemented to investigate the features of Cs, B, and Cs20B80 samples. The influence of contact time (0-72 h), initial RO16 concentration (15-300 mg/L), temperature (30, 40, and 50 °C), the quantity of adsorbent (1-4 g/L), ion strength (0.1-1 M), and solution pH (3-10) on RO16 adsorption onto Cs20B80 were explored. The pseudo-second-order and the Langmuir models fit adequately the adsorption kinetic results and the isotherms ones respectively. Also, the maximal monolayer capacities calculated using the non-linear form of the Langmuir isotherm are 55.27, 55.29, and 70.80 mg/g, at 30, 40 and 50 °C. Based to the statistical physics model, the RO16 could be retained on the surface of Cs20B80 through a non-parallel orientation. The RO16 adsorption process is endothermic and natural, as demonstrated by thermodynamic studies. After three regeneration cycles, the Cs20B80 composite has shown an adsorption capacity of around 20 % compared to the initial one. The adsorption energy of RO16 onto Cs, B, and Cs20B80 examined using the Monte Carlo simulation method (MC) ranged from -164.8 to -303.7 (kcal/mol), showing the potential of the three adsorbants for RO16 dye. Also, the process of adsorption of RO16 dye on the surface of Cs20B80 composite indicates several kinds of physical interactions, involving electrostatic interaction, hydrogen bonding, and π-π interactions, this finding was proved theoretically via molecular dynamic simulations.

Adsorption Properties of Anionic Dyes on Quaternized Microcrystalline Cellulose

Efficient removal of dyes in the wastewater of dyeing and printing industries is challenging, especially the anionic dyes with strong stability, serious environmental pollution, and difficult degradation. In the present work, a novel cationic adsorbent was synthesized through the quaternization of 2,3-epoxypropyltrimethylammonium chloride (GTA) onto microcrystalline cellulose and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, specific surface and pore size analysis, and scanning electron microscopy. Acid Yellow 128 (AY-128) and Acid Red 1 (AR-1) were selected to investigate their adsorption on quaternized microcrystalline cellulose (QMCC). The experimental adsorption results indicated that (1) the adsorption kinetics of AY-128 and AR-1 on QMCC could be consistent with the pseudo-second-order and Freundlich models, respectively; (2) the adsorption process was spontaneous and feasibly endothermic. The removal efficiency of AY-128 and AR-1 was up to 99 and 95%, respectively. After five times of reuse, the removal efficiency of AY-128 and AR-1 was still 97 and 95%. In conclusion, quaternized microcrystalline cellulose was a promising adsorbent for AY-128 and AR-1.

Controlled design of Na-P1 zeolite/ porous carbon composites from coal gasification fine slag for high-performance adsorbent

Low-cost and concentrated industrial wastes have been recognized as a sustainable resource for preparation of new functional materials. Here, a new method was designed for the synthesis of porous composites containing high-purity Na-P1 zeolite and porous carbon from waste coal gasification fine slag (CGFS), which was treated first by acid leaching to controllably remove metal impurities and adjust Si/Al ratio, followed by NaOH fusion and hydrothermal treatment. By leaching with 1.0 mol/L HCl solution, the Si/Al ratio of the raw CGFS increased to 5.7, and the obtained CZ-1.0 consisted of high-purity Na-P1 zeolite with a typical cone-shaped flower cluster shape. The residue carbon in CGFS can be further activated to form porous carbon and graphite carbon layers interposed in the zeolite structure. The specific surface area and pore volume of CZ-1.0 reached 153.91 m²/g and 0.18 cm³/g, respectively. CZ-1.0 exhibited remarkable adsorption performance for methylene blue (MB) with the adsorption capacity reaching 137.5 mg/g for 100 mg/L MB solution. The adsorption process is mainly controlled by the chemisorption mechanism, and the adsorption of MB by CZ-1.0 may include ion exchange, hydrogen bond interaction, π-π bond interaction and van der Waals force. NaCl solution was successfully used as the desorption agent to regenerate the composite material, and the removal rate remained above 92% after five cycles. This work provides an effective strategy to synthesize a practically applicable adsorbent from the waste coal gasification fine slag for the purification of MB wastewater.

Photocatalytic degradation of bisphenol a from aqueous solution using bismuth ferric magnetic nanoparticle: synthesis, characterization and response surface methodology-central composite design modeling

PURPOSE

Bisphenol A (BPA), as endocrine-disrupting compound (EDC), is extensively used as an important chemical in the synthesis of polycarbonate polymers and epoxy resins. BPA absorption into the body can result in the development of metabolic disorders such as low sex-specific neurodevelopment, immune toxicity, neurotoxicity and interference of cellular pathway. Therefore, the presence of BPA in the body and the environment can create hazards that must reach standards before being discharged into the environment.

METHODS

In this study, bismuth ferric nanomagnetic (BFO NMPs) were successfully synthesized via sol-gel method and developed as photocatalysts for BPA removal under visible light irradiation. FE-SEM, TEM, PL, XRD, UV-Vis DRS, VSM, EDX, and FTIR were used to characterize the BFO NMPs.

RESULTS

RSM model (R2 = 0.9745) showed a good correlation between experimental and predicted removal efficiency of BPA. The investigation of four independent variables indicated that pH had the most significant positive effect on the degradation of BPA. Under optimal conditions (pH = 4.042, catalyst dose = 7.617 mg, contact time = 122.742 min and BPA concentration = 15.065 mg/L), maximum degradation was calculated to be 98.7%. After five recycles, the removal of BPA remained >82%, which indicated the proper ability to reuse the catalyst.

CONCLUSION

In conclusion, it can be stated like BPA, the prepared BFO NMPs is a promising photocatalyst for practical application in organic pollutant decomposition.

Adsorptive removal of organic dyes via porous materials for wastewater treatment in recent decades: A review on species, mechanisms and perspectives

Organic dyes, a type of high toxic and carcinogenic chemicals that present severe threats to human and aquatic life, are the most commonly seen organic pollutants in wastewater of industries such as textile, rubber, cosmetic industry etc. Various techniques for the removal of dyes are compared in this review. Adsorption has proven to be a facile and promising approach for the removal of dyes in wastewater. This work focuses on the latest development of various porous materials for the adsorption of organic dyes. The characteristics, functionalization and modification of different porous materials are also presented. Furthermore, adsorption behaviors and mechanism of these adsorbents in the adsorption of organic dyes are critically reviewed. Finally, challenges and opportunities for future research in the development of novel materials for the highly efficient removal of dyes are proposed.

Adsorption isotherm models: A comprehensive and systematic review (2010-2020)

Among numerous methods developed in purification and separation industries, the adsorption process has received considerable attention due to its inexpensive, facile, and eco-friendly nature. The importance of the adsorption process causes extraordinary endeavors for modeling the adsorption isotherms during the years; thus, myriads of research have been conducted and many reviews have been published. In this paper, we have attempted to gather the most widely used adsorption isotherms and their related definitions, along with examples of correlated work of the recent decade. In the present review, 37 adsorption isotherms with about 400 references have been collected from the research published in the period of 2010-2020. The adsorption isotherms utilized are alphabetically organized for ease of access. The parameters of each isotherm, as well as the applicable definitions, are presented in the table, in addition to being discussed in the text. Another table is provided for the practical use of researchers, featuring the usage of the related isotherms in peer-reviewed studies.

Preparation and characterization of magnetic modified bone charcoal for removing Cu2+ ions from industrial and mining wastewater

Heavy metal water pollution is an urgent global problem to be addressed. Copper ions are common toxic heavy metal pollutants in wastewater. In order to remove the excessive copper ions in wastewater, in this study, chicken bone charcoal was modified by sodium dodecyl sulfonate and combined with magnetic nanoparticles prepared with ferric chloride hexahydrate and ferrous sulfate heptahydrate to produce a high efficiency adsorbent. The characterization of the magnetically modified bone charcoal was analyzed by scanning electron microscopy, surface and porosity analyses, FTIR and thermogravimetric analysis. The optimal adsorption conditions of magnetically modified bone charcoal for Cu²⁺ were obtained through batch experiments. The highest removal rate and adsorption capacity of Cu²⁺ was 99.98% and 15.057 mg/g, respectively, when the pH was 3.0, adsorbent dosage was 0.2 g, initial concentration of the Cu²⁺ solution was 50 mg/L, and temperature was 25 °C. The adsorption process fitted well with the Langmuir isotherm and the pseudo-second-order kinetic model. The regeneration experiment indicated that M-SDS-BC-500 maintained a high removal rate after five repetitions. The results suggest that the adsorbent has wide application prospects.

The use of eggshell membrane for the treatment of dye-containing wastewater: Batch, kinetics and reusability studies

The worldwide consumption of eggs is very high, leading to about 250,000 tons of eggshell membrane (ESM) waste annually. The present research thus investigated the potential use of ESM as an inexpensive and abundant adsorbent for Reactive Red 120 (RR120) in aqueous solutions, a widespread hydrophilic azo dye used in the textile industry. The chemical structure and morphology of ESM were characterized using various spectroscopic methods, including scanning electron microscopy, Fourier transform infrared spectroscopy, and elemental analysis. It was found that natural ESM has a porous structure and surface functional groups that are suitable for the adsorption of the target molecules. The impact of the operating conditions, including the variation in the pH and temperature, on the RR120 sorption capacity and mechanisms of ESM was also analyzed. The maximum monolayer adsorption ability of ESM for RR120 was found to be 191.5 mg/g at 318 K, and the sorption process was spontaneous and endothermic. The adsorption of RR120 onto ESM was significantly influenced by the solution pH and the use of NaOH as eluent, indicating that the driving force for this adsorption was electrostatic attraction. Subsequent desorption experiments using 0.1 M NaOH resulted in satisfactory recovery efficiency. Kinetic, isothermic, and thermodynamic analysis was also conducted to support the experimental findings. The experimental results for the adsorption kinetics of ESM were fitted by a pseudo-second-order model. In conclusion, ESM has the potential to be utilized as an eco-friendly and cost-effective adsorbent for the removal of RR120 from aqueous solutions.

Application of chitosan-alginate bio composite for adsorption of malathion from wastewater: Characterization and response surface methodology

Agricultural effluents in aqueous media have caused serious threats due to adversely affect human health and the ecosystem. In this study, the low-cost easily accessible chitosan-alginate adsorbent was prepared for the removal of malathion from agricultural effluents using microemulsion method. The adsorbent was characterized using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The optimum experimental conditions, including adsorbent dosage (0.05-0.25 g), contact time (5-25 min), and concentration of malathion (5-25 mg L^-1) at five levels were studied using the composite central design (CCD) based on the response surface methodology (RSM). The highest removal percentage was obtained 82.35 with an adsorbent dosage of 0.18 g, contact time of 20 min, and initial concentration of 10 mg L^-1. The analysis of variance (ANOVA) was applied to assess the significance and adequacy of the model. The results revealed that quadratic model was proper for the prediction removal of malathion. The adsorption kinetics and isotherms were examined under optimal conditions. The Langmuir with a coefficient of determination (R²) = 0.99 and pseudo-second-order with R² = 0.99 were achieved as the best isotherm and kinetic models, respectively. The results showed that the chitosan-alginate biopolymer can be effective and affordable adsorbent for the removal of malathion from aqueous solution.

Modified wheat straw-derived graphene for the removal of Eriochrome Black T: characterization, isotherm, and kinetic studies

A cost-effective and environment-benign adsorbent was prepared from an abundant agro-waste material. Wheat straw was reduced to graphene and then modified by crosslinking to epichlorohydrin. During the conversion process of wheat straw to graphene, the specific surface area increased more than 100 times (from 4 to 415 m² g^-1). The adsorption efficiency of raw wheat straw, graphene nanosheets, and modified graphene against Eriochrome Black T (EBT) were 8.0, 34.7, and 74.4%, respectively. The modified graphene was further investigated for the effect of environmental condition, i.e., pH (3 to 11), EBT concentration (25-100 mg L^-1), adsorbent dosage (0.25-0.75 g L^-1), contact time (5-60 min), and solution temperature (30-60 °C). The dye removal remained at a high level under a wide range of pH from 3 to 9. The EBT removal decreased from 87.3 to 54.5 by increasing dye concentration and increased from 38.2 to 85.4% by increasing adsorbent dose in the studied ranges. Dye removal also increased by mixing time from 5 to 30 min, whereas a slight drop was observed by continuing agitation up to 60 min. Conducting experiments at various temperatures revealed an endothermic process. Pseudo-first-order and pseudo-second-order models were adequate to represent the adsorption kinetics. Isotherm models suggest a multilayer adsorption of EBT molecules on heterogeneous modified graphene surface with a maximum adsorption capacity of 146.2 mg g^-1. The present work demonstrated that the modified graphene obtained from available and low-cost agro-wastes could be used effectively as adsorbent against EBT from aqueous media.

Dye removal from water and wastewater by nanosized metal oxides - modified activated carbon: a review on recent researches

The conventional water and wastewater treatment methods are unable to provide up-to-data organized standards for drinking water and discharging effluents into natural ecosystems. Therefore, developing advanced and cost-effective methods to achieve published standards for water and wastewater and population needs are nowadays necessity. The important parts of this article are providing literature information about dyes and their effects on the environment and human health, adsorption properties and mechanism, adsorbent characteristics, and recent information on various aspects of modified activated carbons with nanosized metal oxides (AC- NMOs) in the removal of dyes. This review also summarized the effect of main environmental and operational parameters such as adsorbent dosage, pH, initial dye concentration, contact time, and temperature on the dye adsorption using AC-NMOs. Furthermore, the applied isotherm and kinetic models have been discussed.

Carboxymethyl cellulose improved adsorption capacity of polypyrrole/CMC composite nanoparticles for removal of reactive dyes: Experimental optimization and DFT calculation

In this study, polypyrrole/carboxymethyl cellulose nanocomposite particles (PPy/CMC NPs) were synthesized and applied for removal of reactive red 56 (RR56)and reactive blue 160 (RB160) as highly toxic dyes. The amount of CMC was found significantly effective on the surface adsorption efficiency. Different optimization methods including the genetic programming, response surface methodology, and artificial neural network (ANN) were used to optimize the effect of different parameters including pH, adsorption time, initial dye concentration and adsorbent dose. The maximum adsorption of RR56 and RB160 were found under the following optimum conditions: pH of 4 and 5, adsorption time of 55 min and 52 min for RR56 and RB160, respectively, initial dye concentration of 100 mg/L and adsorbent dose of 0.09 g for both dyes. were obtained for RR56 and RB160, respectively. Also, the results indicated that ANN method could predict the experimental adsorption data with higher accuracy than other methods. The analysis of ANN results indicated that the adsorbent dose is the main factor in RR56 removal, followed by time, pH and initial concentration, respectively. However, initial concentration mostly determines the RB160 removal process. The isotherm data for both dyes followed the Langmuir isotherm model with a maximum adsorption capacity of 104.9 mg/g and 120.7 mg/g for RR56 and RB160, respectively. In addition, thermodynamic studies indicated the endothermic adsorption process for both studied dyes. Moreover, DFT calculations were carried out to obtain more insight into the interactions between the dyes and adsorbent. The results showed that the hydrogen bondings and Van der Waals interactions are dominant forces between the two studied dyes and PPy/CMC composite. Furthermore, the interaction energies calculated by DFT confirmed the experimental adsorption data, where PPy/CMC resulted in higher removal of both dyes compared to PPy. The developed nanocomposite showed considerable reusability up to 3 cylces of the batch adsorption process.

Zwitterion composite chitosan-epichlorohydrin/zeolite for adsorption of methylene blue and reactive red 120 dyes

In this research, an attempt to develop zwitterion composite adsorbent is conducted by modifying chitosan (CHS) with a covalent cross-linker (epichlorohydrin, ECH) and an aluminosilicate mineral (zeolite, ZL). The zwitterion composite adsorbent of chitosan-epichlorohydrin/zeolite (CHS-ECH/ZL) is performed multifunctional tasks by removing two structurally different cationic (methylene blue dye, MB), and anionic (reactive red 120 dye, RR120) dyes from aqueous solutions. The surface property, crystallinity, morphology, functionality, and charge of the CHS-ECH/ZL are analyzed using BET, XRD, SEM, FTIR, and pH_pzc, analyses, respectively. The influence of pertinent parameters namely CHS-ECH/ZL dosage (0.02-0.5 g), solution pH (4-10), temperature (303-323K), initial dye concentration (30-400 mg/L), and contact time (0-600 min) on the MB and RR120 removal are tested. The research findings revealed that the adsorption isotherm at equilibrium well explained in according to the Freundlich isotherm model, and the recorded adsorption capacities of CHS-ECH/ZL are 156.1 and 284.2 mg/g for MB and RR120 respectively at 30 °C. The mechanism of MB and RR120 adsorption onto the CHS-ECH/ZL indicates various types of interactions namely, electrostatic interaction, hydrogen bonding, and Yoshida H-bonding in addition to n-π interaction. Overall, this research introduces CHS-ECH/ZL composite as an eco-friendly zwitterion adsorbent with good applicability towards the two structurally different cationic and anionic dyes from aqueous environment.

From microporous to mesoporous mineral frameworks: An alliance between zeolite and chitosan

Microporous and mesoporous minerals are key elements of advanced technological cycles nowadays. Nature-driven microporous materials are known for biocompatibility and renewability. Zeolite is known as an eminent microporous hydrated aluminosilicate mineral containing alkali metals. It is commercially available as adsorbent and catalyst. However, the large quantity of water uptake occupies active sites of zeolite making it less efficient. The widely-used chitosan polysaccharide has also been used in miscellaneous applications, particularly in medicine. However, inferior mechanical properties hampered its usage. Chitosan-modified zeolite composites exhibit superior properties compared to parent materials for innumerable requests. The alliance between a microporous and a biocompatible material with the accompaniment of negative and positive charges, micro/nanopores and proper mechanical properties proposes promising platforms for different uses. In this review, chitosan-modified zeolite composites and their applications have been overviewed.