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Due to the severe harmful impacts of industrial dyeing wastewater on ecosystems and human health, proper treatment is crucial. Herein, the use of modified graphite as an adsorbent for dyeing wastewater treatment was investigated in this study. The graphite was oxidized and intercalated using a phosphoric acid–nitric acid–potassium permanganate system and then thermally treated at high temperatures to optimize its structure. By adjusting the thermal treatment temperature, the graphite adsorbent with varying porosity was obtained. The optimized graphite demonstrated significant improvement in adsorption performance for dyes and organic compounds, achieving a removal rate of over 85% for methylene blue (MB) dye. The optimal adsorption performance is achieved with a 1.6 mg modified graphite adsorbent at 60 °C under alkaline conditions for adsorbing 10 ppm MB. Adsorption kinetics and isotherm models were applied to elucidate the adsorption mechanisms. The results fit the Langmuir model, suggesting that monolayer homogeneous adsorption is favorable. Importantly, the results demonstrate that high-temperature treatment can significantly enhance the adsorption properties of coal-based graphite, supporting its application in dyeing wastewater treatment. [ABSTRACT FROM AUTHOR]

AbstractThe current work is directed to study the synthesis of nanostructured polypyrrole (PPy) using an azo dye as a soft template. The as-prepared PPy was applied for the adsorption of methylene blue (MB) dye. The influence of the synthesis conditions on the morphology of the synthesized nanostructured PPy was examined. Different analytical tools were used for characterization of the synthesized nanostructured PPy. The surface area of the as-prepared nanostructured PPy was measured to be 30 m2 g−1 and hence it was applied for the adsorption of MB as a model of organic dyes. The influence of different parameters on the adsorption/removal of MB was investigated. It was found that the alkaline medium enhances the adsorption rate and the adsorption capacity. Upon increasing the system temperature, the adsorption capacity of nanostructured PPy toward MB dye increased. Different kinetic models were studied, and the current system was found to follow pseudo-second order as well as intraparticle diffusion kinetic models. The equilibrium data were examined by applying Langmuir, Freundlich, and Tempkin isotherms and the first model preferably described MB dye adsorption onto the nanostructured PPy. Reusability of the synthesized nanostructured PPy for the adsorption of MB dye was investigated for many cycles. [ABSTRACT FROM AUTHOR]

The employment of green synthesized nanomaterials for water pollution prevention is increasing nowadays. Herein, Mn-doped ZnO nanoparticles were synthesized using Peganum Harmala seed extract and subsequently used for crystal violet (CV) dye removal from aqueous solutions. The first part of the study describes the preparation of the adsorbent (Mn-ZnO NPs) using a simple coprecipitation method. The surface properties of the material were characterized by Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The second part investigates the adsorption of CV dye onto the surface of the prepared Mn-ZnO NPs. Additionally, the isotherm, kinetics, and thermodynamics of the adsorption process were studied in detail. Batch adsorption analysis was carried out by evaluating different parameters, such as the amount of the adsorbent (0.01g to 0.04 g), CV concentration (20 to 80 mg/L), adsorption time (30 to 120 min), and temperature (35 to 65 ⁰C). The maximum CV dye adsorption capacity of the Mn-ZnO NPs was 45.60 mg/g. The thermodynamic study revealed the spontaneous, exothermic, and feasible nature of the adsorption process, primarily driven by physical forces. Kinetic and isotherm analyses indicated that the adsorption of the dye best fit the Freundlich isotherm and pseudo-second-order models, respectively. Mn-doped ZnO is considered an effective adsorbent for CV, benefiting from its rapid and easy preparation, non-toxic nature, and 94 % adsorption efficiency. The material holds potential for future applications in the removal of organic dyes from wastewater.. [ABSTRACT FROM AUTHOR]

In this study, a hydrothermal approach was employed to graft chitosan (Chit)/algae (ALG) with salicylaldehyde (SA), resulting in the synthesis of a biocomposite named salicylaldehyde-based chitosan Schiff base/algae (Chit-SA/ALG). The main objective of this biocomposite was to effectively remove methyl violet (MV), an organic dye, from aqueous solutions. The adsorption performance of Chit-SA/ALG toward MV was investigated in detail, considering the effects of three factors: (A) Chit-SA/ALG dose (ranging from 0.02 to 0.1 g/100 mL), (B) pH (ranging from 4 to 10), and (C) time (ranging from 10 to 120 min). The Box–Behnken design (BBD) was utilized for experimental design and analysis. The experimental results exhibited a good fit with both the pseudo-second-order kinetic model and the Freundlich isotherm, suggesting their suitability for describing the MV adsorption process on Chit-SA/ALG. The maximum adsorption capacity of Chit-SA/ALG, as calculated by the Langmuir model, was found to be 115.6 mg/g. The remarkable adsorption of MV onto Chit-SA/ALG can be primarily attributed to the electrostatic forces between Chit-SA/ALG and MV as well as the involvement of various interactions such as n–π, π–π, and H-bond interactions. This research demonstrates that Chit-SA/ALG exhibits promising potential as a highly efficient adsorbent for the removal of organic dyes from water systems. The novelty of this work comes from introducing a new bio-organic based composite adsorbent of chitosan (Chit) biopolymer and algae (ALG) biomass. Moreover, the functionality and chemical stability of Chit–ALG composite was further developed by grafting process with salicylaldehyde (SA) using hydrothermal process. The incorporation of ALG biomass into polymeric matrix of Chit and grafting process with SA makes Chit a unique hybrid adsorbent toward cationic dye (methyl violet dye). [ABSTRACT FROM AUTHOR]

AbstractIn this report we present a simple synthesis of a nickel-based metal organic framework (MOF-Ni) at the room temperature using a solution of dimethylformamide (DMF), ethanol and distilled water. The MOF-Ni synthesized in various solvents displayed numerous different properties and advantages over other materials including easy synthesis procedure, good crystallinity, rigidity, and robust chemical stability. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA) were employed to analyze the as-synthesized MOF-Ni. The as-obtained MOF-Ni was used to investigate its adsorption kinetics of red telon dye (RTL) molecules. The effects of time (30–270 min), initial RTL concentration (20–300 mg/L), adsorbent dose (2–50 mg), solution pH (2–12), and temperature (10–80 °C) were investigated. The pseudo-first order rate equation was able to provide the best description of the adsorption kinetics data in the studied time scale. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms, and the isotherm constants were also determined. Dye adsorption turned out to strongly depend on pH, and a low pH was found to increase the amount of adsorbed dyestuff. Compared with other samples, MOF-Ni synthesized in (DMF ​+ ​C2H5OH ​+ ​H2O) had a significantly enhanced adsorption ability for RTL dye. The MOF-Ni high adsorption capacity for RTL dye was attributed to the electrostatic attraction/repulsion phenomena. Moreover, MOF-Ni showed an improved stability at 370, 417, and 423 °C temperatures. The results obtained through our experiments suggested that our porous MOF-Ni microstructures synthesized in DMF ​+ ​C2H5OH ​+ ​H2O have potential applications for treating wastewaters containing RTL dyes. [ABSTRACT FROM AUTHOR]

Rapid industrialization and ever-growing human activities have caused more and more serious water pollution in the last few decades, posing great threats towards both human health and ecological environment. Organic dyes, as one of the major water pollutants, are usually toxic, chemically stable, and hard to degrade. In this paper, a novel PCN-222(Zn)/GO composite was obtained by combining porphyrin-based metal organic framework material PCN-222(Zn) with graphene oxide (GO). The structure and morphology of the composite were characterized by FTIR, XRD, SEM, and optical microscopy. The thermal stability and optical properties were studied by thermogravimetric analysis (TGA) and fluorescence spectroscopy. PCN-222(Zn) and PCN-222(Zn)/GO were used as both adsorbents and photocatalysts for the adsorption and visible light photodegradation of organic dye methylene blue in aqueous solutions. It is found that the blending of GO can improve the photocatalytic degradation activity of PCN-222(Zn) towards organic dyes. [ABSTRACT FROM AUTHOR]

Water contamination caused by textile dyes can affect human health, calling for effective treatment method. Here, we report the preparation of MgFe2O4/C composite through hydrothermal method to adsorb three dyes including rhodamine B, methyl orange (MO) and acid yellow 17 (AY) in water. MgFe2O4/C obtained a surface area of 692.32 m2/g and MgFe2O4 particles were well-dispersed on porous carbon matrix. Taguchi experimental design (L16) was conducted to test the effect of four factors, including initial concentration, adsorbent dosage, contact time and pH at different four levels. pH was a first-ranked factor for adsorption of all three dyes with the highest contribution between 33.20 and 55.61%. The highest capacity (158.12 mg/g) was determined for MO dye adsorption under a concentration of 40 mg/L, pH 3, a dose of 0.05 g/L, and a duration of 240 min. The experiments of MgFe2O4/C reusability were performed, reaching at least fourth cycles offering potential for reuse. It is recommended that Taguchi orthogonal array design can be well adopted to reach the best condition of organic dyes adsorption by MgFe2O4/C composite. [ABSTRACT FROM AUTHOR]

To achieve the actual application of MoO x in absorption removal of organic dye from water, eco-friendly, facilely-scalable, high-yield, and cost-efficient synthesis of MoO x with desirable structures and superior adsorption capacities remains a great challenge. Herein, for the first time, a novel synthetic route to MoO 3 micro-/nanocrystals with different microstructures was based on mechanochemical reactions and subsequent annealing, and their inherent formation mechanisms were also discussed. Moreover, the adsorption kinetics, thermodynamics, and mechanism of Rhodamine B (RhB) on α h -MoO 3 hybrid were systematically investigated. The results show that the microstructures of MoO 3 can be controlled by facile adjusting the dosage of H 2 C 2 O 4 ·2H 2 O, which leads to the different milling precursors. The bicrystalline hybrid of α-MoO 3 nanosheets and h -MoO 3 microrods (α h -MoO 3 hybrid) exhibits an ultrahigh maximum adsorptive capacity (751.88 mg g−1) for RhB at the high initial concentration (80 mg L−1), more than 3 times enhancement compared to that of α-MoO 3 particles (210.16 mg g−1), which can be attributed to the larger specific surface area (28.77 m2 g−1) and more negative surface potential (−72.00 mV). This work provides a scalable and controllable route to synthesize MoO 3 micro-/nanocrystals with desired microstructures, contributing a promising and excellent adsorbent for the practical removal of organic dyes from water. [ABSTRACT FROM AUTHOR]

The results of evaluating the adsorption and fluorescent properties of azolotriazine compounds and phases based on cadmium sulfide quantum dots in vapors of volatile organic compounds (biomarkers of living systems) are considered. The adsorption properties of phases based on organic dyes and encapsulated semiconductors towards vapors of alcohols, ketones, amines, acids, ammonia, and aldehydes are investigated using direct high-sensitivity piezoelectric quartz microweighing. The spectral properties and their variations in analyte vapors are investigated using various spectroscopy methods (absorption, photoluminescence). The research results are compared, and the potential for optimizing this stage is assessed. It is proposed to evaluate the consistency of methods for predicting changes in fluorescent properties in test systems for volatile organic compounds using the Kendall coefficient of concordance, W. The highest level of agreement (W = 0.89) was observed between the methods of spectrofluorimetry and direct vapor microweighing upon adsorption on phases being potential fillers of test systems. A correlation between the results obtained by different fluorescence methods (visual plate test systems and fluorimetry of phases on paper substrates) is 0.80, which confirms a high degree of consistency in assessments using them in the degree of interaction between the analytes and organic, combined fluorochromes. The methods closely related in the nature of the analytical response do not exhibit better agreement than the method of direct vapor microweighing on microphases of fluorimetric reagents of different nature (cadmium sulfide quantum dots/chitosan, organic azolotriazine compounds, mixed phases). This, in turn, enables the selection of simpler, more available, and more rapid methods and means of analysis in routine experiments. [ABSTRACT FROM AUTHOR]

A series of new granular carbonaceous adsorbents was prepared via single-stage physical and chemical activation of walnut shells. Their suitability for removing various types of organic pollutants (represented by dyes, surfactants and water-soluble polymers) from the liquid phase was assessed. The activation of the precursor was carried out with CO2 and H3PO4 using conventional heating. Activated biocarbons were characterized in terms of chemical composition, acidic–basic nature of the surface, textural and electrokinetic properties as well as thermal stability. Depending on the type of activating agent used during the activation procedure, the obtained biocarbons differed in terms of specific surface area (from 401 to 1361 m2/g) and the type of porous structure produced (microporosity contribution in the range of 45–75%). Adsorption tests proved that the effectiveness of removing organic pollutants from the liquid phase depended to a large extent on the type of prepared adsorbent as well as the chemical nature and the molecular size of the adsorbate used. The chemically activated sample showed greater removal efficiency in relation to all tested pollutants. Its maximum adsorption capacity for methylene blue, poly(acrylic acid), poly(ethylene glycol) and Triton X-100 reached the levels of 247.1, 680.9, 38.5 and 61.8 mg/g, respectively. [ABSTRACT FROM AUTHOR]

In an attempt to reuse fibrous textile waste and, at the same time, to address dye pollution in textile wastewater, waste cotton-based yarn was utilized as a cheap and sustainable adsorbent, as well as a row material for carbon adsorbent production. Unmodified yarn and cotton-based carbon adsorbents were used as adsorbents for dye removal from water. Cotton and cotton/polyester yarn samples underwent thermal modification through carbonization followed by chemical activation with KOH. Various techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption isotherms, and surface charge determination, were employed to analyze the morphological and surface characteristics of the cotton-based adsorbents. Adsorption properties were evaluated by testing the removal of selected cationic and anionic dyes from water. The impact of temperature, initial pH and concentration of the dye solution, and contact time on adsorption were investigated, and experimentally obtained data were analyzed using theoretical models. While carbonization alone did not significantly enhance adsorption properties, activated samples exhibited high efficacy in removing both cationic and anionic dyes from water. Despite the negative influence of the polyester component in the carbon precursor on the efficiency of activated samples in removing methyl orange, the results indicated that activated cotton and cotton/polyester yarn could be used to prepare highly efficient adsorbents for the rapid removal of methylene blue from real wastewater samples. [ABSTRACT FROM AUTHOR]

The need to effectively remove toxic organic dyes from aquatic systems has become an increasingly critical issue in the recent years. In pursuit of this objective, polydopamine (PDA)-binary ZIF-8/UiO-66 (MOFs) was synthesized and incorporated into cellulose acetate (CA), producing ZIF-8/UiO-66/PDA@CA composite nanofibers under meticulously optimized conditions. The potential of fabricated nanofibers to remove cationic methylene blue (MB) dye was investigated. Various analysis tools including FTIR, XRD, SEM, zeta potential, BET, tensile strength testing, and XPS were employed. Results revealed a substantial leap in tensile strength, with ZIF-8/UiO-66/PDA@CA registering an impressive 2.8 MPa, as a marked improvement over the neat CA nanofibers (1.1 MPa). ZIF-8/UiO-66/PDA@CA nanofibers exhibit an outstanding adsorption capacity of 82 mg/g, notably outperforming the 22.4 mg/g capacity of neat CA nanofibers. In binary dye systems, these nanofibers exhibit a striking maximum adsorption capacity of 108 mg/g, establishing their eminence in addressing the complexities of wastewater treatment. Furthermore, the adsorption data fitted to the Langmuir isotherm, and the pseudo-second-order kinetic model. The fabricated nanofiber demonstrates good reproducibility and durability, consistently upholding its performance over five cycles. This suite of remarkable attributes collectively underscores its potential as a robust, durable, and highly promising solution for the effective and efficient removal of pernicious MB dye, in the context of both water quality improvement and environmental preservation. [ABSTRACT FROM AUTHOR]

This work demonstrated enhanced adsorption capabilities of lignin nanoparticles (LNPs) synthesized via a straightforward hydrotropic method compared to pristine lignin (PL) powder for removing methylene blue dye from aqueous solutions. Kraft lignin was used as a precursor and p-toluenesulfonic acid as the hydrotrope to produce spherical LNPs with ~ 200 nm diameter. Extensive characterization by SEM, AFM, DLS, zeta potential, and BET verified successful fabrication of microporous LNPs with fourfold higher specific surface area (14.9 m2/g) compared to PL (3.4 m2/g). Significantly reduced particle agglomeration and rearranged surface chemistry (zeta potential of −13.3 mV) arising from the self-assembly of lignin fractions under hydrotropic conditions enabled the application of LNPs and superior adsorbents compared to PL. Batch adsorption experiments exhibited up to 14 times higher methylene blue removal capacity, from 20.74 for PL to 127.91 mg/g for LNPs, and ultrafast equilibrium uptake within 3 min for LNPs compared to 10 min for PL. Kinetic modeling based on pseudo-first-order and pseudo-second-order equations revealed chemisorption as the predominant mechanism, with a rate constant of 0.032825 g/mg·h for LNPs—over an order of magnitude higher than PL (0.07125 g/mg·h). Isotherm modeling indicated Langmuir monolayer adsorption behavior on relatively uniform lignin surface functional groups. The substantially augmented adsorption performance of LNPs arose from the increased surface area and abundance of surface functional groups, providing greater accessibility of chemically active binding sites for rapid dye uptake. Overall, this work demonstrates that tailoring lignin nanoparticle structure and surface chemistry via scalable hydrotropic synthesis is a simple and sustainable approach for producing highly efficient lignin-based nano-adsorbents for organic dye removal from industrial wastewater. [ABSTRACT FROM AUTHOR]

The current study employed the hydrothermal approach to graft chitosan functionalized-SiO2 nanoparticles with an aromatic aldehyde (salicylaldehyde, SA) to obtain an organic–inorganic nanohybrid composite of salicylaldehyde-based chitosan Schiff base/SiO2 (CTS-SA/SiO2) for uptake of an acidic azo dye (acid red 88, AR88) from aqueous media. The effects of A: CTS-SA/SiO2 dose (0.02–0.1 g), B: pH (4–10), and C: time (10–90 min) on the adsorption performance of CTS-SA/SiO2 towards AR88 were studied systematically by the Box–Behnken Design (BBD). The CTS-SA/SiO2 dosage, pH, and contact time resulted in maximum dye elimination (76.46%) of AR88, according to the results of the BBD model. These variables were 0.093 g of CTS-SA/SiO2, pH 4.5, and 87.4 min. The pseudo-second order and Langmuir isotherm provide an account of the experimental results for AR88 adsorption by CTS-SA/SiO2. The calculated maximum Langmuir adsorption capacity for CTS-SA/SiO2 is equal to 184.2 mg/g. The high adsorption of AR88 onto the CTS-SA/SiO2 can be mainly ascribed to electrostatic forces between the protonated CTS-SA/SiO2 and the AR88 anions, along with n–π, π–π, and H-bond interactions. This research demonstrates that CTS-SA/SiO2 has promising potential as an adsorbent for organic dye removal from water systems. [ABSTRACT FROM AUTHOR]

The presence of organic dyes in wastewater raises significant environmental and human health concerns, owing to their high toxicity. In light of this, a novel adsorbent material with porous cryogel architecture was developed and employed for the effective removal of organic dyes from an aqueous solution. Initially, a titanium dioxide nanowire doped with zirconium HZTO was synthesized by the hydrothermal process. Subsequently, the beads (SA/HZTO) of sodium alginate and HZTO were successfully prepared through a cross-linking process, employing Ca2+ ions as the crosslinking agent. Structural analysis of SA/ HZTO beads was performed using FTIR, SEM, and EDX techniques. We systematically examined the impact of different conditions, including the initial dye concentration, pH, contact time, and adsorbent dosage, on the adsorption process. Batch experiments, both in signal and binary systems, were conducted to rigorously assess the dye adsorption capabilities. Kinetic modeling revealed that the adsorption process adhered to the pseudo-second-order kinetic model. Remarkably, the prepared beads exhibited impressive adsorption capacities of 26 and 29 mg/g toward methylene blue (MB) and safranin (SF), respectively. SA/ HZTO beads have demonstrated excellent adsorption properties, offering a promising avenue for the development of low-cost, efficient, and reusable adsorbent to remove dyes from wastewater. [ABSTRACT FROM AUTHOR]

The removal of multiple organic dyes contained in industrial wastewater poses a significant challenge, and the underlying mechanisms involved in their simultaneous removal are still not fully understood. In this work, Nickel–Iron layered double hydroxides nanosheets were successfully synthesized by coprecipitation method at constant pH and were characterized by powder x-ray diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and their effectiveness in removing anionic dyes Remazol Red 23, and Indigo Carmine was investigated by studying several parameters such as initial solution pH, adsorbent dose, dye concentration, and temperature effect. The as-prepared nanocomposite exhibited excellent removal efficiency for Remazol Red 23 and Indigo Carmine reaching the maximum adsorption capacities of 133.04 mg.g−1 and 115.59 mg.g−1, respectively. The simultaneous removal of binary anionic dye mixture was studied and proved the high performance of the synthesized material due to the electrostatic attraction. Also, a cationic dye Basic Yellow 28 was successfully removed when it was added to the binary anionic dyes' mixture, and this was explained by two proposed mechanisms: surface charge modification and the synergetic effect of dyes molecules. [ABSTRACT FROM AUTHOR]

Amyloid fibrils derived from different proteins have been proved as a promising material for adsorption of various pollutants from wastewater, which showed advantages of low cost and eco-friendliness. However, most of the amyloid fibrils derived from animal-based proteins with high environmental footprint, while more sustainable amyloid fibrils derived from plant materials are desirable. In this study, a plant-derived amyloid fibril was extracted from the commonly used wheat flour with a simple and scalable protein purification and fibrillization process. Interestingly, the amyloid fibrils showed good adsorption capacity towards typical organic dyes (Eosin Y (EY) and Congo red (CR)) from contaminated water. Adsorption kinetic analysis indicated the adsorption process to EY or CR by wheat flour amyloid well fitted with a pseudo-second-order model. The adsorption also followed a Langmuir isothermal model with adsorption capacities of 333 mg/g and 138 mg/g towards CR and EY, respectively. This work demonstrated the feasibility to utilize the plant-based amyloid fibril for organic dyes removal from contaminated water, which provided an affordable, sustainable and scalable tool for organic dyes removal from wastewater. Highlights: The use of plant-based amyloid fibrils for organic dyes adsorption is demonstrated. The wheat flour-derived amyloid fibrils exhibit excellent adsorption performance. The adsorption kinetics and isotherms mechanisms are explored. The plant-based amyloid fibrils provide sustainable tool for pollutant management. [ABSTRACT FROM AUTHOR]

Water polluted by organic dyes is normally present in industrial production, which seriously threatens environmental safety. Research on dye adsorption has recently been related to nanomaterials due to their large specific surface area. However, there are still some problems associated with their preparation, application, and recovery. In this study, we developed the one‐step synthesis of lignocellulosic‐Fe(OH)3 hybrid fibers by in situ growth of Fe(OH)3 nanoparticles on lignocellulosic, which could be used as effective adsorbents for dye removal. The formed Fe(OH)3 nanoparticles were dispersed homogeneously on the surface of lignocellulosic. The as‐prepared hybrid fibers featured a large absorption capacity for methylene blue, up to 150.9 mg/g. In a fixed‐bed column separation process, dye pollutants were successfully removed from the water even at a high speed of 5.0 mL/min, with the separation efficiency higher than 99.99%. Remarkably, 1.0 g of lignocellulosic‐Fe(OH)3 was capable of separating over 1200 mL of dye solution continuously and thoroughly. Notably, the underlying adsorption mechanism analyses suggested that multi‐interactions of hydrogen bonds, π–π interactions, and coordinate bonds contribute to the adsorption ability of lignocellulosic‐Fe(OH)3. [ABSTRACT FROM AUTHOR]

The presence of organic dyes and heavy metal ions in water sources poses a significant threat to human health and the ecosystem. In this study, hydrogel adsorbents for water pollution remediation were synthesized using Guipi residue (GP), a cellulose material from Chinese herbal medicine, and chitosan (CTS) through radical polymerization with acrylamide (AM) and acrylic acid (AA). The characteristics of the hydrogels were analyzed from a physicochemical perspective, and their ability to adsorb was tested using model pollutants such as Pb2+, Cd2+, Rhodamine B (RhB), and methyl orange (MO). The outcomes revealed that GP/CTS/AA-co-AM, which has improved mechanical attributes, effectively eliminated these pollutants. At a pH of 4.0, a contact duration of 120 min, and an initial concentration of 600 mg/L for Pb2+ and 500 mg/L for Cd2+, the highest adsorption capabilities were 314.6 mg/g for Pb2+ and 289.1 mg/g for Cd2+. Regarding the dyes, the GP/CTS/AA-co-AM hydrogel displayed adsorption capacities of 106.4 mg/g for RhB and 94.8 mg/g for MO, maintaining a stable adsorption capacity at different pHs. Compared with other competitive pollutants, GP/CTS/AA-co-AM demonstrated a higher absorption capability, mainly targeted toward Pb2+. The adsorption processes for the pollutants conformed to pseudo-second-order kinetics models and adhered to the Langmuir models. Even after undergoing five consecutive adsorption and desorption cycles, the adsorption capacities for heavy metals and dyes remained above 70% and 80%. In summary, this study effectively suggested the potential of the innovative GP/CTS/AA-co-AM hydrogel as a practical and feasible approach for eliminating heavy metals and dyes from water solutions. [ABSTRACT FROM AUTHOR]

Water pollution has become a major environmental threat owing to the expeditious development of industries. These industries rapidly release wastewater containing harmful dyes (organic pollutants), which significantly affect the lives of humans and aquatic organisms to a huge extent. Therefore, the elimination of the pollutants in the contaminated water has become the primary need of the moment that is to be treated before it discharges into the environment. This article mainly focuses on the adsorption mechanism of the organic dye methylene blue from wastewater under sunlight using a zinc-metal organic framework (Zn-MOF). The Zn-MOF, being a three-dimensional porous structure was synthesized by the direct precipitation method using zinc metal ions and terephthalic acid (or) benzene-1,4-dicarboxylic acid as a connecting linker. Then, morphological and optical characterizations, along with the analysis of thermal and surface parameters, were performed for the synthesized Zn-MOF. The synthesized Zn-MOF appeared to be in a cubic form with a pore volume of about 0.006 cc/g. It was also found to have a surface area of 4.705 m2/g, with an absorbance range of 239.39 nm. The elemental composition of zinc in the synthesized Zn-MOF was approximately 25.41%, proving that the synthesized MOF is a Zinc-based MOF. As the results showed many properties related to the adsorption mechanism, Zn-MOF was chosen to proceed with the adsorptive application of removing the methylene blue dye from wastewater under sunlight. This application provides an efficient solution for the treatment of wastewater through the adsorption property of Zn-MOF, thereby proving its potential as an adsorbent. [ABSTRACT FROM AUTHOR]

Corncob-β-cyclodextrin composites(CB-β-CD) were synthesized in one-pot using corncob and P-cyclodextrin as raw materials. CB-β-CD Were characterized by FTIR, SEM, BET and thermogravimetry. The adsorption performance of CB-β-CD was tested by adsorbing dye molecules(AF) and MG under different conditions. The results showed that the initial mass concentration of 20 mL dye was 30 mg/L and add long adsorbent the adsorption time was 3 h, the maximum adsorption amounts of CB-β-CD for MG and AF were 52.16 mg/g and 58.04 mg/g, respectively. The adsorption of MG was better under alkaline conditions, while AF was adsorbed better under acidic conditions. The adsorption of AF and MG is more in line with the quasi second-order kinetic model and Langmuir isotherm adsorption type, and the adsorption process is mainly single-molecule layer and chemical adsorption. After five cycles of reuse, the adsorption performance of the material can still reach above 90%. [ABSTRACT FROM AUTHOR]

Synthetic organic dyes, which are resistant to biodegradation, pose a notable health risk, potentially leading to cancer and respiratory infections. Researchers have addressed this concern by exploring physicochemical methods to remove organic dyes from wastewater. A particularly promising solution involves modified biochar adsorbents, which demonstrate high efficiency in organic dye removal. Biochar, a charcoal-like material derived from biomass pyrolysis, offers advantages such as low cost, eco-friendliness, high efficiency and reusability. Beyond its role in sustainable soil remediation, biochar proves effective in removing organic dyes from wastewater after undergoing physical or chemical modification. Acid–base activation or metal–heteroatom impregnation enhances biochar's adsorption capacity. This comprehensive review examines the attributes of biochar, common methods for production and modification, and the impacts of raw materials, pyrolysis temperature, heating rate and residence time. It further elucidates the biochar adsorption mechanism in the removal of organic dyes, assessing factors influencing efficiency, including biochar feedstock, solution pH, adsorption temperature, particle size, initial dye concentration, biochar dosage and reaction time. It explores challenges, opportunities, reusability and regeneration methods of biochar in treating organic dye wastewater. It also discusses recent advances in organic dye removal using adsorption-based biochar. The review ultimately advocates for enhancing biochar's adsorption performance through post-modification.

This review investigated depth literature survey on the removal of various heavy metals and dyes contamination. The current study is a broad review of the different methods of preparation of biowaste adsorbent from rice husk and rice straw that has been implemented for the adsorption of many hazardous heavy metals and dyes in order to reduce their harmful effect on the environment. The selection of rice waste-based material for the adsorption process was considered due to its cost-effectiveness, easy availability, high adsorption efficiency, and reusability. This study is a comprehensive review of the adsorption of toxic heavy metals and dyes using rice husk and rice straw-based adsorbents either in bare or in modified forms under different physicochemical processes. In addition, some parameters affecting adsorption capability like pH, initial dye concentration, equilibrium time, temperature, adsorbent dosage, and shaking or stirring speed influence the adsorption mechanism have been discussed thoroughly. The applicability of various adsorption isotherm models and adsorption kinetic models for dye adsorption by various rice husk and straw biomass adsorbents is also reported here. Finally, from the literature reviewed conclusions have been drawn and also proposed a few future research suggestions. [ABSTRACT FROM AUTHOR]

Due to their detrimental and carcinogenic effects, synthetic organic dyes pose significant environmental and health risks. Consequently, addressing the bioremediation of industrial wastewater containing these organic dyes has become an urgent environmental concern. The adsorption using low-cost and green materials is one of the best alternative techniques for the removal of dyes. This study aims to investigate the use of chitin to eliminate Congo red (CR), an anionic dye, from wastewater. The chitin was produced from shrimp shell in a quick and environmentally friendly manner by utilizing a co-solvent (glycerol/citric acid (GLC)). The resulting adsorbent was characterized through various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR spectroscopy. The effectiveness of CR removal with chitin was studied with respect to contact time, adsorbent dose, initial pH, equilibrium isotherms, and kinetic and thermodynamic parameters. It was observed that variations in the dye concentration and pH significantly influenced the removal of CR with chitin. Under optimal operating conditions (pH = 7, contact time = 130 min, temperature = 50 °C), the adsorption capacity reached 29.69 ± 0.2 mg/g. The experimental data revealed that CR adsorption onto a chitin adsorbent is better represented by a Langmuir isotherm. [ABSTRACT FROM AUTHOR]

The modification of the Tetraselmis sp. algae material (Tetra-Alg) with surfactant Cethyltrimethylammonium Bromide (CTAB) yielded adsorbent Tetra-Alg-CTAB as an adsorbent of methyl orange (MO) and methylene blue (MB) solutions. The characterization of the adsorbent used an infrared (IR) spectrometer to identify functional groups and Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDX FEI Inspect-S50, Midland, ON, Canada) to determine the surface morphology and elemental composition. Methyl orange and methylene blue adsorption on the adsorbent Tetra-Alg, Tetraselmis sp. algae-modified Na+ ions (Tetra-Alg-Na), and Tetra-Alg-CTAB were studied, including variations in pH, contact time, concentration, and reuse of adsorbents. The adsorption of MO and MB by Tetra-Alg-CTAB at pH 10, during a contact time of 90 min, and at a concentration of 250 mg L−1 resulted in MO and MB being absorbed in the amounts of 128.369 and 51.013 mg g−1, respectively. The adsorption kinetics and adsorption isotherms of MO and MB and Tetra-Alg, Tetra-Alg-Na, and Tetra-Alg-CTAB tend to follow pseudo-second-order kinetics models and Freundlich adsorption isotherms with each correlation coefficient value (R2) approaching 1. Due to the modification with the cationic surfactant CTAB, anionic dyes can be strongly sorbed in alkaline pH due to strong electrostatic attraction, while MB is more likely to involve cation exchange and hydrogen bonding. The reuse of Tetra-Alg-CTAB was carried out four times with adsorption percent > 70%, and the adsorbent was very effective in the adsorption of anionic dyes such as MO. [ABSTRACT FROM AUTHOR]

Pharmaceuticals have emerged as a new class of ecological pollutants and have majorly contributed to harmful effects on the environment and human health. The presence of these pharmaceuticals in wastewater treatment plants, ground, and seawater has been reported widely. Organic dyes and other organic contaminants which are being considered as emerging contaminants are now in the race among the top organic pollutants that need effective treatment. Removal of these contaminants via green adsorbents has become an essential requirement towards a green and cleaner environment. Herein, we report the efficacy of the novel greener porous graphene obtained via the near-green synthesis method as an adsorbent material for treating seven organic pollutants: Methyl orange, Methyl red, Rhodamine-B, Ciprofloxacin, Atenolol, Ibuprofen, and Carbamazepine. Batch tests were conducted to investigate the effect of adsorption time and varying adsorbent dosages. The obtained greener porous graphene showed fast kinetics, which was determined to be guided by pseudo second-order kinetics and the maximum pollutant removal efficiency (>80%) was seen at a high adsorbent dosage (2 mL injected from a 5 g/L solution). Furthermore, the nonlinear adsorption modeling confirmed that the greener porous graphene followed the Langmuir model for the dye rhodamine-B sorption and the Freundlich model for all the other six contaminants. This greener porous graphene can be considered an effective adsorbent for the removal of organic pollutants in wastewater. [ABSTRACT FROM AUTHOR]

The preparation of high performance, low cost and recyclable adsorbents is very important to cope with the increasingly devastating water pollution. As a typical three-dimensional porous carbon material, carbon foam (CF) is expected to be a highly efficient adsorbent to wipe out organic dyes from wastewater. However, the uneven size distribution, and lack of adsorption sites signified by insufficient foaming process limit its wider application in the environmental field. Here, CF/carbon nanotubes/graphene oxide (CF/CNTs/GO) composites (adsorbents) were prepared by press-assisted foaming and carbonization methods using mesophase precursors of coal tar pitch and CNTs followed by impregnation of GO nanosheets. The results highlighted that the addition of CNTs facilitated improvement in pore distribution, porosities, and mechanical properties (20 MPa). After treating with GO nanosheets, the adsorption performances of CF/CNTs/GO adsorbents substantially improved due to the increased active sites in the CF/CNTs and the adsorption rate and capacity of methylene blue (MB) reached 73.1% and 146 mg/g respectively. Further, adsorption isotherms (Langmuir and Freundlich), thermodynamics, quasi-first order and quasi-second order kinetics and intraparticle diffusion models were employed to investigate the adsorption mechanism. This work provides a low-cost fabrication technique for the high-performance CF/CNTs/GO adsorbent and is expected to provide reference for application in the treatment of contaminated water. [ABSTRACT FROM AUTHOR]

Biochar is a potential porous carbon to remove the contaminants from aquatic environments. Herein, N-doped hierarchical biochar was produced by the combined approach of ammonia torrefaction pretreatment (ATP) and alkali activation. ATP could not only incorporate N element into poplar wood, but obtain the loose structure of poplar wood. The highest surface area of N-doped hierarchical biochar was 2324.61 m2 g−1 after ammonia wet torrefaction pretreatment, which was higher than that of activation carbon (1401.82 m2 g−1) without torrefaction pretreatment, the hierarchical biochar (2111.03 m2 g−1) without ammonia atmosphere. The N-doped hierarchical biochar presented the highest adsorption capacity (564.7 mg g−1) of methyl orange (MO), which was 14.64-fold of that on biochar without N doping. In addition, the pseudo-second-order and Langmuir model fitted well with the adsorption kinetics and isotherms of the N-doped hierarchical biochar. The incorporation of nitrogen element could not only tune the distribution of surface electrons on biochar, but optimize the ambient condition of adsorption active sites as well. The adsorption of MO might occur on the N-/O-containing functional groups through the electrostatic interaction, the π-π dispersion interaction, and the hydrogen bonding. The density functional theory showed that the graphitic-N and pyridinic-N were the dominant adsorption active sites. Highlights: Ammonia torrefaction pretreatment coupled with alkali activation was developed for the preparation of N-doped hierarchical biochar. AWTP had better performance on N-doping and increasing of BET than ADTP. Graphitic-N and pyridinic-N were dominant active sites for the adsorption of organic dye. [ABSTRACT FROM AUTHOR]

Numerous catalysts for water pollutant mitigation have been developed over recent decades. However, the utilization of catalysts embedded in 3D structures remains challenging. This study aims at fabricating 3D-printed TiO2/SiO2/polymer scaffolds for the degradation of organic dyes, specifically Methylene Blue (MB) and rhodamine B (Rh B). The TiO2/SiO2/polymer scaffolds were fabricated by stereolithography (SLA) technique, using TiO2 photocatalyst synthesized via a solution combustion process, silica adsorbent prepared from sugarcane leaves, and photocurable resin as feedstock. X-ray diffraction analysis confirmed that TiO2 exhibited anatase/rutile/brookite triphasic structure while SiO2 possessed amorphous structure. Scanning electron micrographs revealed that TiO2 and SiO2 particles uniformly deposited on the surface of the photocurable resin. The adsorption activity of the TiO2/SiO2/polymer scaffolds was examined in the dark for 24 h to ensure that adsorption equilibrium was achieved. Photocatalytic examinations were conducted under UV light (λ = 365 nm). The TiO2/SiO2/polymer scaffolds efficiently demonstrated their potential dye removal efficiency against MB and Rh B dyes as 81.9% and 60%, respectively. Reusability testing revealed that after hydrogen peroxide treatment, the used scaffolds exhibited the degradation ability in a comparable range to the as-fabricated scaffolds. An application of a 3D printing technique for water pollution reduction was successfully demonstrated in this study. [ABSTRACT FROM AUTHOR]

Seeking efficient, reusable, and low-budget adsorbent materials for the removal of industrial effluent is of great interest for the community of environmental chemistry. In this work, a mesoporous phenolic resin-type polymer was successfully synthesized by one-step solvothermal synthesis starting from two relatively cheap polymer monomers (i.e., phloroglucinol and 4,4′-Biphenyldicarboxaldehyde), and it exhibited excellent adsorption capacity toward both methylene blue (728.63 mg/g) and Pb (II) (176.08 mg/g) at 308 K. Based on a variety of characterizations on this material and a systematic study on the effect of various working conditions (including concentration, temperature, pH value, and ionic strength), we conclude that the adsorption for methylene blue and Pb(II) on phenolic resin-type polymer was consistent with pseudo-second-order kinetic equation (R2 > 0.98) and Langmuir model (R2 > 0.97); adsorptions were thermodynamically endothermic and occurred spontaneously; adsorptions were driven by the electrostatic interaction between phenolic resin-type polymer and Methylene blue or Pb (II). Our research demonstrated the potential application of phenolic resin-type polymer in the elimination of two different types of pollutants from wastewater. [ABSTRACT FROM AUTHOR]

In this work, Mg(OH)2-based adsorbents were synthesized by the impinging-streams approach combined with the bubble-template method and were applied to remove the Congo red (CR) from the water. Material characterizations revealed that the prepared Mg(OH)2 adsorbents possessed a mesoporous microsphere structure with a specific surface area of 9.249 m2/g. The adsorption experiments showed that the first 5 min were critical for the adsorption process, as it basically reached the adsorption equilibrium during this period. Impressively, a saturated adsorption amount of 504 mg/g was achieved, under the given experimental conditions, where the temperature was maintained at 298 K, the adsorbent dosage was 40 mg/30 mL, and the adsorption process lasted for 2 h. The enhanced removal effect can be attributed to the microsphere structure, which provides more stable binding sites for contaminants. The adsorption kinetics and isotherms of Mg(OH)2 microsphere adsorbents followed pseudo-second-order kinetic and Langmuir isotherm models, respectively. Additionally, the adsorption process was found to be exothermic and spontaneous. Physical adsorption mechanisms based on hydrogen bonding and pore diffusion are hypothesized to explain the adsorption process. After seven adsorption–desorption cycles, the Mg(OH)2 microspheres remained above 85% of the maximum adsorption capacity. Therefore, the Gas-continuous Impinging Streams (GIS) technique can be effectively utilized for the preparation of magnesium hydroxide microsphere adsorbents that exhibit excellent adsorption stability. [ABSTRACT FROM AUTHOR]

This article presents the results of an assessment of the use of CdSe, NiCdSe, and CoCdSe thin films as a basis for photocatalysts used for the decomposition of the organic dyes rhodamine B, cargo red, and indigo carmine. Interest in this area was determined by the need to solve a number of issues related to increasing the efficiency purifying aqueous media from the negative effects of organic dyes, which cannot be disposed of using traditional methods associated with adsorption or filtration. The use of the electrochemical synthesis method to obtain thin films of a given thickness showed that the addition of nickel or cobalt sulfates to the standard electrolyte solution used to obtain CdSe films results in the formation of CdSe films with a higher degree of structural ordering (the crystallinity degree was more than 50%), as well as a decline in the band gap. When analyzing data on the photocatalytic decomposition of organic dyes, it was found that a change in the structure of the films due to the introduction of nickel and cobalt leads, in the case of the decomposition of the rhodamine B dye, to a more efficient decomposition, and in the case of the cargo red and indigo carmine dyes, not only to their complete decomposition and mineralization, but also to a reduction in the time of photocatalytic reactions (decomposition growth rate). Moreover, an analysis of cyclic tests demonstrated that NiCdSe and CoCdSe films maintain 90% of their photocatalytic decomposition efficiency compared to that achieved during the first decomposition cycle, while CdSe degrades after three consecutive cycles and its efficiency reduces by more than 2.5–3 times. [ABSTRACT FROM AUTHOR]

The presence of dyes in effluents from textile industries has a detrimental effect on aquatic ecosystems as it hinders the process of photosynthesis by reducing the penetration of sunlight. The adsorption capacity of a carbon foam-based iron oxide sorbent obtained from natural sources for the removal of organic methylene blue (MB) dye from water was investigated. The adsorption capacities were examined by batch experiments, wherein the impacts of varying iron content, sorbent dosage, contact time, dye concentration, and characterization were assessed. The physical characteristics and surface morphology of the synthesized carbon foam were also investigated. The carbon precursor and iron oxide precursor were coalesced within a singular container and subjected to carbonization process. This resulted in the formation of a porous structure that is capable of effectively providing support to the iron oxide particles. The carbon foam produced is a self-assembled formation that possesses the characteristic shape and underlying network structure reminiscent of bread. As the number of nanoparticles went up, so did the number of active sites. At elevated temperatures, the interactions between the dye molecules were enhanced, resulting in a more efficient process of dye removal. The magnetite sample exhibited endothermic adsorption, and all other samples exhibited exothermic adsorption. The adsorption of MB onto iron supported by carbon foam did not exhibit intraparticle diffusion as the only rate-limiting step for all samples. The adsorption rate was governed by a multistep elementary reaction mechanism in which multiple processes occurred simultaneously. The experimental data in this study may be accurately modeled by the pseudo-second-order kinetic model (R2 > 0.96). Additionally, the Freundlich isotherm best describes the adsorption equilibrium, which is supported by the outstanding fit of data to the model (R2 > 0.999). The findings suggest that the utilization of a natural carbon foam as a support for an immobilized iron oxide sorbent demonstrates considerable effectiveness in the removal of methylene dye from industrial effluent. [ABSTRACT FROM AUTHOR]

The latest developments in the adsorption of organic dyes by adsorbents (metal oxides, modified metal oxides) were addressed in this review study. The main goal of this paper is to sort out the dispersion information of adsorbent materials, which are often employed in organic dye adsorption. The review dedicated to the specific dyes adsorption using various adsorbent (metal oxides, modified metal oxides). The review covers the adsorption process including parameters, kinetics, and isotherms. The review gives the brief information of Congo red (CR) adsorption using metal oxide nano‐adsorbents which provide readers with massive dye specific collection. For the first time, several metal‐doped materials that absorb organic dyes are summarized and addressed. The review includes adsorption of organic dyes using single metal oxide, bimetallic oxide, trimetallic oxide, and modified metal oxide. This study also summarized the effects of critical factors such as pH, initial dye concentration, adsorbent dosage, contact time, and temperature on dye adsorption utilizing metal oxide nano‐adsorbents. In addition, the kinetic and applied isotherm models have been discussed. Finally, a few recommendations are made for further research on adsorbent materials. [ABSTRACT FROM AUTHOR]

Hydrogen titanate (H2Ti3O7) nanotubes, synthesized via the hydrothermal process, are one of the advanced adsorbents used for the treatment of aqueous solutions containing harmful organic dyes. Although various advanced oxidation processes (AOPs) have been demonstrated to regenerate the H2Ti3O7 nanotubes, an ozonation (O3)-based AOP still remains unexplored for this purpose. Hence, in the present work, this technique has been demonstrated, for the first time, to regenerate the H2Ti3O7 nanotubes after the adsorption of cationic methylene blue molecules on their surfaces from an aqueous solution. The effect of various test parameters, such as the O3 flow rate (2–6 g h−1), an ozonation time (10–60 min), and an initial regeneration solution pH (2–10), on the regeneration efficiency of ozonation-based AOP has been systematically investigated. The O3 flow rate, ozonation time, and initial regeneration solution pH of 6 g h−1, 60 min, and 6.6 (neutral) respectively have been observed to be the most optimum values for the complete regeneration of H2Ti3O7 nanotubes. The mechanism of the regeneration of nanotubes via an ozonation-based AOP has been ascertained by using the hydroxyl (●OH) and superoxide (O2●−) radical-trapping as well as the hydroperoxyl (●OOH) radical-scavenging experiments which unambiguously reveal that the ●OOH radicals, having a lower oxidation potential, are primarily responsible for the regeneration of H2Ti3O7 nanotubes. Five consecutive regeneration cycles of H2Ti3O7 nanotubes have been demonstrated which confirms that the high adsorption capacity of H2Ti3O7 nanotubes is maintained even after the repeated number of adsorption cycles which suggests the consistency of ozonation-based AOP. [ABSTRACT FROM AUTHOR]

The importance of water for all living organisms is unquestionable and protecting its sources is crucial. In order to reduce water contaminants, like toxic metals and organic dyes, researchers are exploring different techniques, such as adsorption, photocatalytic degradation, and electrolysis. Novel materials are also being sought. In particular, biopolymers like guar gum and xanthan gum, that are eco-friendly, non-toxic, reusable, abundant and cost-effective, have enormous potential. Gum-based nanocomposites can be prepared and used for removing heavy metals and colored dyes by adsorption and degradation, respectively. This review explains the significance of gum-based nanomaterials in waste water treatment, including preparative steps, characterization techniques, kinetics models, and the degradation and adsorption mechanisms involved. [ABSTRACT FROM AUTHOR]

The presence of organic dyes in wastewater raises significant environmental and human health concerns, owing to their high toxicity. In light of this, a novel adsorbent material with porous cryogel architecture was developed and employed for the effective removal of organic dyes from an aqueous solution. Initially, a titanium dioxide nanowire doped with zirconium HZTO was synthesized by the hydrothermal process. Subsequently, the beads (SA/HZTO) of sodium alginate and HZTO were successfully prepared through a cross-linking process, employing Ca2+ ions as the crosslinking agent. Structural analysis of SA/HZTO beads was performed using FTIR, SEM, and EDX techniques. We systematically examined the impact of different conditions, including the initial dye concentration, pH, contact time, and adsorbent dosage, on the adsorption process. Batch experiments, both in signal and binary systems, were conducted to rigorously assess the dye adsorption capabilities. Kinetic modeling revealed that the adsorption process adhered to the pseudo-second-order kinetic model. Remarkably, the prepared beads exhibited impressive adsorption capacities of 26 and 29 mg/g toward methylene blue (MB) and safranin (SF), respectively. SA/HZTO beads have demonstrated excellent adsorption properties, offering a promising avenue for the development of low-cost, efficient, and reusable adsorbent to remove dyes from wastewater.

The preparation of biochar capped magnetic nanoparticles as adsorbents for the removal of methylene blue (MB), bromophenol blue (BPB) and rhodamine B (RhB) dyes is reported. Morphological studies of the untreated magnetic biochar nanoadsorbent showed monodispersed particles of about 20 nm. Brunauer, Emmett and Teller (BET) analysis revealed surface area of 138.28 m2/g while saturation magnetization was 12.61 emu/g. The energy bandgap of pure magnetite was reduced from 4.03 to 2.70 eV after capping with biochar. Maximum adsorption capacity (Qo) of the dyes onto the magnetic biochar are 14.39, 16.47 and 2.65 mg/g for MB, RhB and BPB respectively. The Langmuir equation best interpreted the sorption of methylene blue while Freundlich equation was more suitable for the sorption of bromophenol blue and Rhodamine B dyes. FTIR spectra of the magnetic biochar nanoadsorbent after adsorption indicated that uptake of the organic dyes occurred through physisorption. Competitive adsorption studies indicate the sorption of methylene blue, and bromophenol blue dyes occurred in acidic medium in comparison to neutral and alkaline media. The result from the study also shows that ethanol is the best eluent for the desorption of the organic dyes and eluted about 70% of adsorbed dyes in the first run.

We synthesized a γ-irradiated chitosan-ZnO-AgNPs (ICZA) composite by using a simple hydrogels method. We evaluated its adsorption/photocatalytic degradation abilities for the removal of an organic dye and its antibacterial activity. The XRD, SEM, TEM, EDS, and FTIR techniques were used to characterize the obtained samples. Based on the adsorption and degradation of methylene blue (MB) in the dark and under UV light irradiation, the adsorption and the photocatalytic activity of the as-obtained samples were evaluated. The optimum conditions for synthesizing the composite were as follows: contact time of 210 min, a dosage of 2 g/L, MB concentration of 40 mg/L, and a solution pH of 8.0. The ICZA had a high adsorption capacity, which was suitable for removing MB from the aqueous solutions; it showed a maximum adsorption capacity (qm) of 92.59 mg/g. The fit of the adsorption isotherms with the Langmuir model was satisfactory. The photocatalytic degradation ability of the composite was also better than that of other catalysts in the presence of UV light, with an apparent rate constant (kapp) of 3.08 × 10−2. The synthesized ICZA also showed good antibacterial activity against Staphylococcus aureus, with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 12.5 g/mL and 50 g/mL under light-incubation and dark-incubation conditions. Finally, we discussed the hypothesized mechanism of the adsorption/photocatalytic activity and antibacterial activity of the ICZA composite in this study. [ABSTRACT FROM AUTHOR]

In this study, proanthocyanidins-functionalized Fe3O4 magnetic nanocomposites were synthesized by the hydrothermal method. The prepared Fe3O4 nanocomposites were characterized by Fourier transform infrared spectrometer (FTIR), X-ray powder diffractometer (XRD), physical property measurement system (PPMS), particle size analyzer, scanning electron microscope (SEM), and transmission electron microscope (TEM). FTIR results indicated that the obtained products were coated with proanthocyanidins. The SEM and TEM results, as well as particle size distribution analysis, revealed that the obtained products were spherical particles with average diameter of 3 2 8. 6 2 ± 2 6. 7 5 nm. XRD and PPMS characterization confirmed that the Fe3O4 nanoparticles have a cubic spinel structure with magnetic properties. The performance of the Fe3O4 nanocomposites for removing organic dyes in an aqueous solution was investigated. The synthesized products were found to be effective on removing various organic dyes, such as Methylene blue (MB), neutral red (NR) and Rhodamine B (RhB), indicating their considerable potential as efficient dyes adsorbents for wastewater treatment. Proanthocyanidins-functionalized Fe3O4 magnetic nanocomposites were synthesized by the hydrothermal method. The obtained Fe3O4 nanocomposites can efficiently remove the organic dyes in an aqueous solution. Proanthocyanidins-functionalized Fe3O4 magnetic nanocomposites had the potential to be developed as efficient dyes adsorbents for wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, a green and effective adsorbent of chitosan/montmorillonite/algae (CHI/MMT/ALG) composite was developed to be an alternative adsorbent to remove dyestuffs including basic green 1 (BG1) and reactive blue 19 (RB19) from the aqueous solutions. The physicochemical characteristics of CHI/MMT/ALG were analyzed using XRD, CHN–O, BET, FTIR, pHpzc, and SEM analytical techniques. The findings of the characterization revealed that the increased surface functionalities offered an enticing platform for the improved adsorption of cationic and anionic dye molecules. The essential adsorption variables, such as A: CHI/MMT/ALG dosage (0.02–0.08 g), B: pH (4–9), and C: duration (5–30 min), were optimized using the Box-Behnken design (BBD) approach. The BG1 adsorption process demonstrated a better match with the Langmuir model, whereas the RB19 adsorption process exhibited a better fit with both the Temkin and Langmuir models. The fitting of the kinetic analysis illustrates that the BG1 and RB19 adsorption by CHI/MMT/ALG could be better represented by a pseudo-second-order model. The maximum adsorption capacity of CHI/MMT/ALG for BG1 and RB19 was specified to be 509.5 mg/g and 227.9 mg/g, respectively. The endothermicity and spontaneity of the BG1 and RB19 adsorption processes are evidenced by thermodynamic analysis. The improved surface functionalities of CHI/MMT/ALG inspired the adsorption mechanism of CHI/MMT/ALG for BG1 and RB19 could be essentially ascribed by electrostatic attraction, n-π stacking, and hydrogen bonding. Overall, the study's findings indicate that the newly developed CHI/MMT/ALG has significant potential for the removal of synthetic dye from aqueous. [ABSTRACT FROM AUTHOR]

Fe-Co-Ni-S (FCNS) nanocomposite is prepared through a hydrothermal method as a new efficient adsorbent to remove organic dyes in wastewater. The morphology, elemental composition and crystalline structure of the adsorbents have been studied by scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The influence of the dosage of adsorbent and the pH value on the adsorption performance, the reusability of the nanocomposite, and effects of different anions are studied, which show that the adsorption rate of FCNS towards Rhodamine B (RhB) is as high as 99.63%. The adsorption kinetics of RhB on FCNS is described to pseudo-second- order model. At 318 K, the saturated adsorption capacity is 581.4 mg/g, which is consistent with the Langmuir isotherm. The kinetic results indicate that the adsorption process involves three steps, among which chemical adsorption and intraparticle diffusion play important roles. In addition, through the thermodynamic fitting of the adsorption process, it indicates that the adsorption of RhB by FCNS is spontaneous and accompanied by endothermic reaction. The FCNS nanocomposites has good adsorption performance under pH values ranging from 3 to 11. The FCNS has good reusability and adsorption performance after being reused 5 times. The Fourier-transform infrared spectrum indicates that hydrogen bonding is one of the main factors for influencing the adsorption. Compared with monometallic or bimetallic sulfides, the composite presented here has better adsorption performance and higher adsorption capacity, which will inspire some other emerging trimetallic sulfide composites for various advanced applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Controlled growth of CeO 2 nanoparticles (NPs) on reduced graphene oxide (rGO) layers was designed and synthesized via heterogeneous reactions of Ce3+ ions and oxygen-containing functional groups. • The growth process of CeO 2 NPs was studied using the in-situ TEM analysis. • We identified the key formation mechanisms of in-situ grown CeO 2 NPs on rGO layers and reported good adsorption-photocatalytic activities of the as-synthesized CeO 2 @rGO. • Degradation rate of rhodamine B using the composite reached 94.7% within 120 min, and after five cycles, the degradation rate was still maintained at 87.2%. Nanostructured composites of metal oxides and graphene often exhibit synergistic physicochemical properties, which can be explored for applications in photocatalysis and water treatment. However, there are key issues about effective structure controls such as distributions and sizes of nanoparticles inside these composite materials. Herein, we report a green approach using hydrothermal calcination processes to in-situ grow CeO 2 nanoparticles (with their ultrafine crystalline sizes, homogeneous dispersion and controlled oxygen-vacancy) directly onto surfaces of reduced graphene oxides (rGOs). The growth process of CeO 2 NPs was characterized by in-situ TEM analysis. During the calcination process, oxygen-containing functional groups such as –OH and C O on the rGOs were transformed into H 2 O and CO 2 , which acted as oxidizing agents to react with cerium ions and produce CeO 2 nanoparticles directly onto surfaces of rGOs. Integration of ultrafine crystalline oxygen deficient CeO 2 and electrically conducting rGOs facilitated fast adsorption of reactant molecules and provided numerous active sites, which effectively achieved superior photocatalytic performance and enhanced adsorption capability for colored organic dyes of rhodamine B and methyl orange. Degradation rate of rhodamine B using the composite reached 94.7% within 120 min, and after five cycles, the degradation rate was still maintained at 87.2%, showing good stability and reusability. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of the adsorption efficiency of methylene blue and methyl orange dyes by polyaniline base (PANI), halloysite nanotubes (HNTs), and their nanocomposite (HNTs/PANI). PANI and the nanocomposite were prepared by the chemical oxidative polymerization of aniline in the absence and presence of HNTs followed by subsequent dedoping by ammonia solution. The morphology and thermal stability of the adsorbents were explored. In particular, the TEM method showed that the nanocomposite consisted of practically non-agglomerated nanoparticles with a "core-shell" morphology. Particles of pure polymer are quite agglomerated and form massive aggregates. The kinetics of decreasing the concentration of dyes in solutions upon their contact with adsorbent powders was studied by the method of electron spectroscopy. The HNTs/PANI nanocomposite was found to absorb both dyes with slightly higher efficiency than the PANI base probably due to more developed surface of the former. Processing of the obtained results of adsorption of both dyes on the studied adsorbents according to different kinetic models (pseudo-first and pseudo-second order and intraparticle diffusion) showed that in all cases this process is best described by the pseudo-second order model, which indicates the chemical nature of adsorption. The calculated adsorption capacity of the adsorbents under study appeared be quite close to the experimental one. These materials can be used as effective adsorbents for cleaning wastewaters from organic dyes. [ABSTRACT FROM AUTHOR]