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The development of new efficient materials for the removal of water-soluble toxic organic dyes has been one of the focused research areas in the recent past. There is a strong demand for the new materials as most of the reported techniques/materials suffer from serious limitations. In this regard, a series of flexible chitosan-based task-specific polyurethane foams (PUCS-GP, PUCS-CA-GP, PUCS-TA-GP, and PUCS-GA-GP) associated with naturally available hydroxycarboxylic acids was developed. The basis for the preparation of these task-specific and functionalized PU foams is to possess amine groups for trapping the anionic dyes (example: Orange II denoted as OII) and carboxylic acid groups for attracting the cationic dyes (example: Rhodamine B denoted as RhB) under specified pH conditions. Batch adsorption experiments were conducted to assess and improve various parametric conditions. The experimental results revealed that the adsorption kinetics closely agree with the pseudo-second-order model having a maximum sorption capacity of 38.3 mg/g at pH 3 for OII on PUCS-GP and 48.4 mg/g at pH 6 for RhB on PUCS-CA-GP. Furthermore, the adsorption process was described by isotherms, kinetic equations and thermodynamic parameters (ΔG°, ΔH° and ΔS°). Notably, the regeneration of OII and RhB dyes from the exhausted PUCS-GP and PUCS-CA-GP materials was effectively accomplished. The recovered PUCS-GP shows >90 % OII and PUCS-CA-GP displays >70 % RhB removal efficiency even after twelve adsorption-desorption processes under mild conditions, demonstrating excellent recyclability/durability. The advantages of these functionalized foam materials are facile preparation, high adsorption capacity, good reusability, and very efficient removal of organic dyes from wastewater streams.
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Compuestos Azo , Bencenosulfonatos , Quitosano , Colorantes , Poliuretanos , Rodaminas , Contaminantes Químicos del Agua , Purificación del Agua , Poliuretanos/química , Rodaminas/química , Quitosano/química , Adsorción , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Compuestos Azo/química , Compuestos Azo/aislamiento & purificación , Purificación del Agua/métodos , Bencenosulfonatos/química , Cinética , Colorantes/química , Colorantes/aislamiento & purificación , Concentración de Iones de Hidrógeno , Agua/química , ReciclajeRESUMEN
The dye-contaminated wastewater discharged from various industries such as dye manufacturing, paint, textile, paper, and cosmetic is a prime source of surface water pollution having serious detrimental effects on both the environment and human beings. These hazardous dyes when exposed to water obstruct the penetration of sunlight into the water and thus restrain aquatic plants from generating photosynthetic compounds. Moreover, some dyes are potential cancer-causing and also negatively impact the human nervous and respiratory systems. In this current study, modification of coconut coir powder (CCP) was carried out through cationic surfactant treatment and was successively utilized as the adsorbent for decoloring anionic dye (acid blue 185 (AB 185)) containing waste stream. Further, a comparative investigation of the dye removal efficiency of raw CCP and surfactant-modified coconut coir powder (SMCCP) as the adsorbent was studied. On surfactant treatment, using a very minimal SMCCP dosage of 8.3 g/L, a very high percentage dye removal of 98.4% is possible, whereas with raw CCP, even after using a higher dosage of 14 g/L, only 70.1% dye removal can be achieved. Characterization of SMCCP adsorbent was done by Fourier transform infrared, thermogravimetric, X-ray, and scanning electron microscope analyses. Furthermore, the optimization of critical operating parameters was investigated for the effective adsorption of AB 185 dye in batch mode. The adsorption of AB 185 onto SMCCP was a thermodynamically spontaneous endothermic process, following the Langmuir isotherm and pseudo-second-order kinetic model. Moreover, regeneration of exhausted SMCCP by 0.1 (M) NaOH was achieved with a satisfactorily high recovery of 97% in the first cycle. Subsequently, SMCCP can be successfully reutilized for five consecutive cycles with a loss of 17.6% in the total adsorption capacity. With all such advantages, the present study delivers a new paradigm to utilize the novel adsorbent SMCCP as a promising eco-friendly adsorbent aided by its advantage of regeneration and reusability for the treatment of dye-contaminated wastewater.
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Since the potential carcinogenic, toxic and non-degradable dyes trigger serious environmental contamination by improper treatment, developing novel adsorbents remains a major challenge. A novel high efficiency and biopolymer-based environmental-friendly adsorbent, chitosansodium tripolyphosphate-melamine sponge (CTS-STPP-MS) composite, was prepared for Orange II removing with chitosan as raw material, sodium tripolyphosphate as cross-linking agent. The composite was carefully characterized by SEM, EDS, FT-IR and XPS. The influence of crosslinking conditions, dosage, pH, initial concentration, contacting time and temperature on adsorption were tested through batch adsorption experiments. CTS-STPP-MS adsorption process was exothermic, spontaneous and agreed with Sips isotherm model accompanying the maximum adsorption capacity as 948 mgâg-1 (pH = 3). Notably, the adsorption performance was outstanding for high concentration solutions, with a removal rate of 97 % in up to 2000 mgâL-1 OII solution (100 mg sorbent dosage, 50 mL OII solution, pH = 3, 289.15 K). In addition, the adsorption efficiency yet remained 97.85 % after 5 repeated adsorption-desorption cycles. The driving force of adsorption was attributed to electrostatic attraction and hydrogen bonds which was proved by adsorption results coupled with XPS. Owing to the excellent properties of high-effective, environmental-friendly, easy to separate and regenerable, CTS-STPP-MS composite turned out to be a promising adsorbent in contamination treatment.
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Compuestos Azo , Quitosano , Triazinas , Contaminantes Químicos del Agua , Quitosano/química , Quitosano/análogos & derivados , Adsorción , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Triazinas/química , Compuestos Azo/química , Compuestos Azo/aislamiento & purificación , Concentración de Iones de Hidrógeno , Purificación del Agua/métodos , Bencenosulfonatos/química , Cinética , Polifosfatos/química , Aniones/química , Temperatura , Colorantes/química , Colorantes/aislamiento & purificaciónRESUMEN
Nowadays, dye water pollution is becoming increasingly severe. Composite of MXene, ZnS, and chitosan-cellulose material (MX/ZnS/CC) was developed to remove anionic dyes through the synergistic effect of adsorption and photocatalytic degradation. MXene was introduced as the cocatalyst to form Schottky heterostructure with ZnS for improving the separation efficiency of photocarriers and photocatalytic performance. Chitosan-cellulose material mainly served as the dye adsorbent, while also could improve material stability and assist in generation of free radicals for dye degradation. The physics and chemistry properties of MX/ZnS/CC composite were systematically inspected through various characterizations. MX/ZnS/CC composite exhibited good adsorption ability to anionic dyes with adsorption capacity up to 1.29 g/g, and excellent synergistic effects of adsorption and photodegradation with synergistic removal capacity up to 5.63 g/g. MX/ZnS/CC composite performed higher synergistic removal ability and better optical and electrical properties than pure MXene, ZnS, chitosan-cellulose material, and MXene/ZnS. After compounding, the synergistic removal percentage of dyes increased by a maximum of 309 %. MX/ZnS/CC composite mainly adsorbs anionic dyes through electrostatic interactions and catalyzes the generation of â¢O2-, h+, and â¢OH to degrade dyes, which has been successfully used to remove anionic dyes from environmental water, achieving a 100 % removal of 50 mg/L dye.
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Celulosa , Quitosano , Colorantes , Contaminantes Químicos del Agua , Compuestos de Zinc , Quitosano/química , Adsorción , Celulosa/química , Compuestos de Zinc/química , Colorantes/química , Colorantes/aislamiento & purificación , Catálisis , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/aislamiento & purificación , Sulfuros/química , Purificación del Agua/métodos , Fotólisis , Aniones/químicaRESUMEN
With the increase of sustainable development goal, the bio-based adsorption materials with high and selective dye removal are important for water treatment in the dyeing industry. In this paper, a bio-based adsorption foam composed of metal-organic frameworks (MOF) and polyethyleneimine (PEI)-modified cellulose was prepared by a three-step process, i.e., PEI modification of cellulose fibers (PC), MOF decoration of PEI-modified cellulose (MIL-53@PC), and in-situ foaming with polyurethane. PEI modification provides cellulose fiber with more active sites for both dye adsorption and MOF bonding. We found that MIL-53 crystals were tightly bonded on the surface of PC through hydrogen bonding. Because of the abundant adsorption sites (e.g., amines, iron oxide group), the MIL-53@PC demonstrated high adsorption capacity and selectivity for anionic dye (e.g., 936.5 mg/g for methyl orange) through electrostatic interaction and hydrogen bonding. Finally, MIL-53@PC particles were blended with a waterborne polyurethane prepolymer to prepare a three-dimensional hydrophilic foam (MIL-53@PC/PUF), which not only maintained high adsorption capacity and selectivity of MIL-53@PC and also improved its recyclability and reusability. The MIL-53@PC/PUF offers a promising solution for dye wastewater treatment.
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Celulosa/análogos & derivados , Estructuras Metalorgánicas , Polietileneimina/análogos & derivados , Contaminantes Químicos del Agua , Colorantes/química , Adsorción , Polietileneimina/química , Poliuretanos , Contaminantes Químicos del Agua/químicaRESUMEN
Recently a large number of extensive studies have amassed that describe the removal of dyes from water and wastewater using natural adsorbents and modified materials. Methyl orange dye is found in wastewater streams from various industries that include textiles, plastics, printing and paper among other sources. This article reviews methyl orange adsorption onto natural and modified materials. Despite many techniques available, adsorption stands out for efficient water and wastewater treatment for its ease of operation, flexibility and large-scale removal of colorants. It also has a significant potential for regeneration recovery and recycling of adsorbents in comparison to other water treatment methods. The adsorbents described herein were classified into five categories based on their chemical composition: bio-sorbents, activated carbon, biochar, clays and minerals, and composites. In this review article, we want to demonstrate the capacity of natural and modified materials for dye adsorption which can yield significant improvements to the adsorption capacity of dyes such as methyl orange. In addition, the effect of critical variables including contact time, initial methyl orange concentration, dosage of adsorbent, pH, temperature and mechanism on the adsorption efficiency will be covered as part of this literature review.
The novelty of this review article describes the utility of various natural and modified materials employed to remove methyl orange (MO) from water, wastewater and aqueous solutions. Natural sorbents are very popular adsorbents because the majority of them are affordable and readily accessible in terms of addressing key challenges concerning water security that are relevant to MO adsorption processes.This review is significant since it will be useful in guiding researchers on the selection of an adsorbent that would be suitable for MO adsorption. Furthermore, our findings provide a basis for researchers interested in the design of composite adsorbents based on the selection of constituent components.
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Compuestos Azo , Aguas Residuales , Contaminantes Químicos del Agua , Adsorción , Biodegradación Ambiental , Colorantes , Cinética , Concentración de Iones de HidrógenoRESUMEN
An eco-friendly cationic polyacrylamide (CPAM)-modified diatomite/Ce(III)-crosslinked sodium alginate hybrid aerogel (CPAM-Dia/Ce-SA) was synthesized successfully and characterized by SEM-EDS, XRD, FTIR, UV-Vis and XPS. Adsorption performance, interaction mechanism and reusability of CPAM-Dia/Ce-SA used for the removal of acid blue 113 (AB 113), acid blue 80 (AB 80), acid yellow 117 (AY 117), Congo red (CR) and Direct Green 6 (DG 6) anionic dyes from aqueous media were investigated in detail. The results demonstrate that CPAM-Dia/Ce-SA aerogel is macroscopic polymer hybrid spheres with a particle size of around 1.3 mm, unique undulating mountain-like surface and porous mesostructure, and exhibits outstanding adsorption capacity for anionic dyes and good reusability. The maximum adsorption amounts of AB 113, AB 80, AY 117, CR and DG 6 by CPAM-Dia/Ce-SA were 3008, 1208, 914, 1832 and 1232 mg/g at pH 2.0, 60 min contact time and 25 °C, and corresponding removal efficiency reached individually 97.5, 96.6, 99.7, 99.9 and 98.5 % respectively and were less affected by increasing pH up to 10.0. Dye adsorption behaviour and adsorption processes with spontaneous and exothermic nature were perfectly interpreted by the Langmuir and Pseudo-second-order rate models respectively. Physicochemical and multisite-H-bonding synergies promoted the ultrastrong biosorption of anionic dyes by CPAM-Dia/Ce-SA.
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Colorantes , Contaminantes Químicos del Agua , Colorantes/química , Adsorción , Alginatos/química , Contaminantes Químicos del Agua/química , Cinética , Rojo Congo/química , Agua , Concentración de Iones de HidrógenoRESUMEN
Water pollution by synthetic anionic dyes is one of the most critical ecological concerns and challenges. Therefore, there is an urgent need to find an efficient adsorbent and photocatalyst for dye removal. In the present study, we aimed to fabricate a hybrid mesoporous composite of spongy sphere-like SnO2 and three-dimensional (3D) cubic-like MgO (SnO2/MgO) as a promising adsorbent/photocatalyst to remove the anionic sunset yellow (SSY) dye from real wastewater at neutral pH conditions. The as-synthesized SnO2 and MgO composite was investigated using XRD, SEM, EDX, TEM, XPS, BET, and zeta potential. The experimental study of the SSY removal using SnO2/MgO composite was performed at different conditions, such as pH, stirring time, dose, and temperature. More than 99% of 10 mg/L SSY was effectively adsorbed from aqueous solution using 40 mg of SnO2/MgO composite at pH 7 and a stirring time of 60 min. The SSY adsorption behavior was well fitted by pseudo-second order and the Langmuir model, indicating that the SSY was chemisorbed to the composite-active sites as a monolayer. On the other hand, photocatalytic degradation process exhibited better results in terms of speed of removal and used quantity of photocatalyst, where 20 mg of SnO2/MgO composite can be used to remove > 99% of SSY dye within 30 min. Mechanism of SSY adsorption and photocatalytic degradation was discussed. In addition, elution experiments demonstrated that the SnO2/MgO composite as an SSY adsorbent could be reused for nine cycles without considerable reduction in the SSY adsorption efficiency. Therefore, this work exhibited that the mesoporous SnO2/MgO composite can be considered an effective adsorbent/photocatalyst to remove SSY dye from real industrial effluent water at neutral pH conditions.
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Colorantes , Contaminantes Químicos del Agua , Colorantes/química , Óxido de Magnesio/química , Adsorción , Agua , Contaminantes Químicos del Agua/análisis , Cinética , Concentración de Iones de HidrógenoRESUMEN
The aim of this study is to prepare an eco-friendly bioadsorbent by graft copolymerization and modification from hemp fiber including bio-macromolecules such as cellulose, hemicellulose and lignin for anionic dyes adsorption from aqueous solutions, and to investigate adsorptive properties. The prepared cellulose-supported bioadsorbent (TEPA-(GMA-g-HF)) was characterized in detail using SEM-EDX, STEM, FTIR, XRD, TGA and BET techniques and calculating the point of zero charge. It was used as an adsorbent to remove three different anionic dyes, Remazol Brilliant Blue R (RBBR), Reactive Red 120 (RR120) and Reactive yellow 160 (RY160) from the aqueous medium. The effects of adsorbent amount, pH, initial dye concentration, time and temperature on the adsorption were investigated. From the results, it was determined that the adsorption of all three dyes to the developed fibrous bioadsorbent was more compatible with the pseudo-second-order kinetic and the Langmuir isotherm model. It was found that the adsorption capacity increased with increasing temperature, and the adsorption capacity at 298 K was 91.70 mg/g for RBBR, 83.33 for RY160 and 76.34 mg/g for RR120, respectively. Dye removal efficiencies were provided as approximately 100 % at acidic pHs. This high removal efficiency has also achieved in the dense matrix medium, and even after five consecutive reused.
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Cannabis , Contaminantes Químicos del Agua , Colorantes/química , Celulosa/química , Temperatura , Adsorción , Cinética , Concentración de Iones de Hidrógeno , Contaminantes Químicos del Agua/químicaRESUMEN
In this study, chitosan nanoparticles (ChNs) were used as an adsorbent for single and simultaneous uptake of cationic (methylene blue (MB)) and anionic (methyl orange (MO)) dyes. ChNs were prepared based on the ionic gelation method using sodium tripolyphosphate (TPP) and characterized by zetasizer, FTIR, BET, SEM, XRD, and pHPZC. The studied parameters that affect removal efficiency included pH, time, and dyes' concentration. The results showed that in single-adsorption mode, the removal of MB is better in alkaline pH, contrary to MO uptake which presents higher removal efficiency in acidic media. The simultaneous removal of MB and MO from the mixture solution by ChNs could be achieved under neutral conditions. The adsorption kinetic results showed that adsorption of MB and MO for both single-adsorption and binary adsorption systems comply with the pseudo-second-order model. Langmuir, Freundlich, and Redlich-Peterson isotherms were used for the mathematical description of single-adsorption equilibrium, while non-modified Langmuir and extended Freundlich isotherms were used to fit the co-adsorption equilibrium results. The maximum adsorption capacities of MB and MO in a single dye adsorption system were 315.01 and 257.05 mg/g for MB and MO, respectively. On the other hand, and for binary adsorption system, the adsorption capacities were 49.05 and 137.03 mg/g, respectively. The adsorption capacity of MB decreases in solution containing MO and vice versa, suggesting an antagonistic behavior of MB and MO on ChNs. Overall, ChNs could be a candidate for single and binary removal of MB and MO in dye-containing wastewater.
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Laminar membranes comprising graphene oxide (GO) and metal-organic framework (MOF) nanosheets benefit from the regular in-plane pores of MOF nanosheets and thus can support rapid water transport. However, the restacking and agglomeration of MOF nanosheets during typical vacuum filtration disturb the stacking of GO sheets, thus deteriorating the membrane selectivity. Therefore, to fabricate highly permeable MOF nanosheets/reduced GO (rGO) membranes, a two-step method is applied. First, using a facile solvothermal method, ZnO nanoparticles are introduced into the rGO laminate to stabilize and enlarge the interlayer spacing. Subsequently, the ZnO/rGO membrane is immersed in a solution of tetrakis(4-carboxyphenyl)porphyrin (H2 TCPP) to realize in situ transformation of ZnO into Zn-TCPP in the confined interlayer space of rGO. By optimizing the transformation time and mass loading of ZnO, the obtained Zn-TCPP/rGO laminar membrane exhibits preferential orientation of Zn-TCPP, which reduces the pathway tortuosity for small molecules. As a result, the composite membrane achieves a high water permeance of 19.0 L m-2 h-1 bar-1 and high anionic dye rejection (>99% for methyl blue).
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Sapelli wood sawdust-derived magnetic activated carbon (SWSMAC) was produced by single-step pyrolysis using KOH and NiCl2 as activating and magnetization agents. SWSMAC was characterized by several techniques (SEM/EDS, N2 adsorption/desorption isotherms, FTIR, XRD, VSM, and pHPZC) and applied in the brilliant blue FCF dye adsorption from an aqueous medium. The obtained SWSMAC was a mesoporous material and showed good textural properties. Metallic nanostructured Ni particles were observed. Also, SWSMAC exhibited ferromagnetic properties. In the adsorption experiments, adequate conditions were an adsorbent dosage of 0.75 g L-1 and a solution pH of 4. The adsorption was fast, and the pseudo-second-order demonstrated greater suitability to the kinetic data. The Sips model fitted the equilibrium data well, and the maximum adsorption capacity predicted by this model was 105.88 mg g-1 (at 55 °C). The thermodynamic study revealed that the adsorption was spontaneous, favorable, and endothermic. Besides, the mechanistic elucidation suggested that electrostatic interactions, hydrogen bonding, π-π interactions, and n-π interactions were involved in the brilliant blue FCF dye adsorption onto SWSMAC. In summary, an advanced adsorbent material was developed from waste by single-step pyrolysis, and this material effectively adsorbs brilliant blue FCF dye.
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Carbón Orgánico , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico/química , Madera , Contaminantes Químicos del Agua/química , Termodinámica , Cinética , Fenómenos Magnéticos , Concentración de Iones de Hidrógeno , Azul de Metileno/químicaRESUMEN
There is a dire need to find an efficient, cost-effective, sustainable, and environment-friendly adsorbent for the removal of anionic pollutants such as dyes from waste effluent. In this work, a cellulose-based cationic adsorbent was designed and utilized for methyl orange and reactive black 5 anionic dyes adsorption from an aqueous medium. Solid-state nuclear magnetic resonance spectroscopy (NMR) revealed the successful modification of cellulose fibers, and dynamic light scattering (DLS) evaluations showed the levels of charge densities. Furthermore, various models for adsorption equilibrium isotherm were utilized to understand the adsorbent characteristics, with the Freundlich isotherm model providing an excellent fit for the experimental results. The modelled maximum adsorption capacity was as much as 1010â¯mg/g for both model dyes. The dye adsorption was also confirmed using EDX. It was noted that the dyes were chemically adsorbed through the ionic interaction that can be reversed using sodium chloride solution. Overall, the cationized cellulose is inexpensive, environment-friendly, nature-driven, and recyclable making it an appealing adsorbent feasible for the dye removal from textile wastewater effluent.
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Colorantes , Contaminantes Químicos del Agua , Colorantes/química , Celulosa/química , Contaminantes Químicos del Agua/química , Aguas Residuales , Cationes/química , Adsorción , CinéticaRESUMEN
In this work, a cost-effective chitin-based magnesium oxide (CHt@MgO) biocomposite with excellent anionic methyl orange (MO) dye removal efficiency from water was developed. The CHt@MgO biocomposite was characterized by FT-IR, XRD, SEM-EDX, and TGA/DTG. Results proved the successful synthesis of CHt@MgO biocomposite. Adsorption of MO on the CHt@MgO biocomposite was optimized by varying experimental conditions such as pH, amount of adsorbent (m), contact time (t), temperature (T), and initial MO concentration (Co). The optimized parameters for MO removal by CHt@MgO biocomposite were as follows: pH, 6; m, 2 g/L; t, 120 min. Two common isotherm models (Langmuir and Freundlich) and three kinetic models (pseudo-first-order (PFO), pseudo-second-order (PSO), and intraparticle diffusion (IPD)) were tested for experimental data fitting. Results showed that Langmuir and PFO were the most suitable to respectively describe equilibrium and kinetic results on the adsorption of MO adsorption on CHt@MgO biocomposite. The maximum Langmuir monolayer adsorption capacity (qm) on CHt@MgO biocomposite toward MO dye was 252 mg/g at 60 °C. The reusability tests revealed that CHt@MgO biocomposite possessed high (90.7%) removal efficiency after the fifth regeneration cycle.
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Óxido de Magnesio , Contaminantes Químicos del Agua , Quitina , Espectroscopía Infrarroja por Transformada de Fourier , Agua , Adsorción , Cinética , Contaminantes Químicos del Agua/análisis , Concentración de Iones de HidrógenoRESUMEN
Here we report an efficient strategy to separate and recycle acid blue 93 (AB93) from mixed anionic dyes selectively within sodium hydroxide activated A/CS adsorbent (N-A/CS). This work broke the common sense that the larger the specific surface area, the better the adsorption property is, which provided an alternative strategy to separate dyes. The adsorption equilibrium of AB93 could be achieved approximately within 1-2 min, and the maximum adsorption capacity was up to 2500 mg/g. Besides, it can be activated continuously and reused at least 15 times. In mixed anionic dyes, the adsorption selectivity of N-A/CS on AB93 in the mixture of AB93 and acid fuschin (AF) reached up to 99.7 %. Molecular dynamics simulation revealed that the trend of adsorption energy for dyes qualifies well with the experimental order of adsorption capacities and molecular sizes among five anionic dyes based on molecular matching effect. Thus, N-A/CS is a low-cost, easily-preparable, significantly-effective-and-reusable adsorbent, providing a promising "size-matching" strategy to adsorb multi-component dye systems.
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Quitosano , Contaminantes Químicos del Agua , Acroleína , Hidróxido de Sodio , Cinética , ColorantesRESUMEN
Current study aims to synthesize chitosan/polyvinyl alcohol (CS/PVA), poly(ethyleneimine), and Fe3O4 impregnated beads for co-removal of Cr(VI) and toxic azo-dyes from wastewater. The mesoporous PEI@AC@Fe3O4 exhibits magnetism and enhanced physisorption by higher specific-porosity (2.1 nm) from Cr(VI) radii (0.044 nm). Moreover, surface functional groups (-OH, -NH, -NH2, -COOH etc.), especially amines enhance ionic bonding due to positive zeta potential. Hence, it is unique for anionic dyes removal under a wide pH range. It showed maximum adsorption capacity 98, 85.5, 85.8, and 91%, or 199.8, 148, 167, 176.5 mg g-1 respectively for Cr(VI), tartrazine, sunset yellow, and erythrosine. Surface adsorption of Cr(VI) and its transition into Cr(III) was confirmed by EDX. Langmuir isotherm and pseudo-first-order kinetics best fit the adsorption of Cr(VI) and azo-dyes confirming their monolayer physisorption on adsorbent surface. Synthesized adsorbent examined in wastewater purification prototype for efficient removal of different simulated wastewaters confirms its potential for real-world applications.
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Quitosano , Colorantes de Alimentos , Nanocompuestos , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Cromo/análisis , Colorantes , Concentración de Iones de Hidrógeno , Cinética , Aguas Residuales , Contaminantes Químicos del Agua/análisisRESUMEN
Geopolymers have been recently studied as environmentally friendly and low-cost adsorbents especially for the removal of cationic species in wastewater treatment mainly because of their negative surface charge at spontaneous pH conditions. Although there are very few recent studies conducted with different geopolymer composites on anionic dyes, high cost, difficulty of the composite preparation and most importantly the necessity of very low pH values limit their usage. Hence, in this study, a simple and low-cost surface modification with CTAB was applied to a previously prepared fly ash-based geopolymer (GEO) for the removal of anionic Acid Blue 185 (AB185) without the need of strongly acidic conditions. Within this scope, the effects of CTAB dosage (1-5% by weight of GEO), adsorbent dosage (0.5-3.0 g L-1) and initial dye concentration (10-50 mg L-1) were studied as a function of retention time (5-300 min). For 40 min, the removal efficiency of AB185 substantially increased from 0.29 up to 79.36% for the respective GEO and its modified product with 4% CTAB (MGEO4). The efficiency increased with the adsorbent (MGEO4) dosage of up to 2.0 g L-1 at which 89.20% was obtained for 300 min. However, a little decrease was observed down to 81.10% for 3.0 g L-1. The efficiency values of 98.19 and 89.20% were obtained for the initial AB185 concentrations of 10 and 50 mg L-1, respectively. The Langmuir-Hinshelwood kinetic model is highly correlated with the experimental results. The high adsorption capacity attained in a very short time suggests that the main mechanism is based on physical adsorption via the electrostatic attraction between MGEO4 and AB185. Overall results have indicated that the CTAB-modified fly ash-based geopolymer can be effectively used for the adsorption of AB185.
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Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Ceniza del Carbón , Colorantes , Cinética , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodosRESUMEN
In order to solve the low sorption capacity of pristine biochar for anionic pollutants, e.g., reactive red 120 (RR120), a novel mesoporous Fe-biochar composite was fabricated in this study by combination of Fe-loading and ball-milling methods. The ball-milling Fe-biochar composite could effectively remove RR120 by up to 90.1 mg g-1 at pH of 7.5, and slightly alkaline condition was preferred. Adsorption kinetics showed that ball-milling Fe-biochar composite could quickly sorb RR120 with the rate constant (k2) of 2.07 g mg-1 min-1 (pH = 7.5). Positive surface charge and large surface area were responsible for the outstanding removal performance of RR120 by ball-milling Fe-biochar composite: (1) The adscititious Fe would be converted to ß-FeOOH during pyrolysis, which significantly improved the zeta potential of biochar and thus facilitated the electrostatic adsorption for RR120, which contributed to 42.3% and 85.5% at pH of 3 and 7.5, respectively; (2) Ball-milling effectively increased the specific surface area and uniformed the pore size distribution, which could provide more sorption sites and expedite the diffusion of RR120 molecules, shortening the time from several hours to less than 15 min. Findings of this study not only provide a feasible modification method for biochar to adsorb anionic pollutants efficiently and rapidly, but also help to reveal the roles of Fe-loading and ball-milling in enhancing adsorption capacity.
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Hierro , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Cinética , Contaminantes Químicos del Agua/análisisRESUMEN
Anionic Congo red dye (CR) is not effectively removed by conventional adsorbents. Three novel biochars derived from agro-waste (Acacia auriculiformis), modified with metal salts of FeCl3, AlCl3, and CaCl2 at 500 °C pyrolysis have been developed to enhance CR treatment. These biochars revealed significant differences in effluents compared to BC, which satisfied initial research expectations (P < 0.05). The salt concentration of 2 M realized optimal biochars with the highest CR removal of 96.8%, for AlCl3-biochar and FeCl3-biochar and 70.8% for CaCl2-biochar. The modified biochars were low in the specific surface area (137.25-380.78 m2 g-1) compared normal biochar (393.15 m2 g-1), had more heterogeneous particles and successfully integrated metal oxides on the surface. The CR removal increased with a decrease in pH and increase in biochar dosage, which established an optimal point at an initial loading of 25 mg g-1. Maximum adsorption capacity achieved 130.0, 44.86, and 30.80 mg g-1 for BFe, BCa, and BAl, respectively. As magnetic biochar, which is easily separated from the solution and achieves a high adsorption capacity, FeCl3-biochar is the preferred biochar for CR treatment application.
Asunto(s)
Rojo Congo , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , MetalesRESUMEN
Organic dyes can enter water bodies through industrial wastes and may pose a threat to the health of aquatic organisms and human. Metal organic framework derived carbon materials (CMOFs) have shown excellent performance for aqueous dye adsorption. However, few have studied multimetallic CMOFs for dye removal. Herein, a ternary metal oxide embedded carbon derived from amino-modified metal organic framework (CMOF(Fe/Al/Ni 8/7/5)-NH2) has been developed as an efficient adsorbent to remove aqueous methylene blue (MB) and acid red 73 (AR-73). CMOF(Fe/Al/Ni 8/7/5)-NH2 reached adsorption equilibrium for both MB and AR-73 within 30 min at neutral pH condition. It also achieved 18 and 24 times higher adsorption than commercial activated carbon (AC) in 10 min for MB and AR-73, respectively. Compared to other CMOFs-NH2, CMOF(Fe/Al/Ni 8/7/5)-NH2 had the highest adsorption capacity for both cationic MB and anionic AR-73. In addition, CMOF(Fe/Al/Ni 8/7/5)-NH2 had < 0.15% metal leaching in 90 min in the pH range of 4-10, and it also maintained 89% and 95% adsorption capacity for MB and AR-73 in five consecutive adsorption batches, respectively. Electrostatic interaction was identified as the primary interaction between CMOFs-NH2 and the dyes, and the embedded crystalline metal oxides with different points of zero charge (PZCs) were identified to be the key adsorption sites. A uniformly distributed surface charge model was proposed to explain the exceptional adsorption capacity of CMOF(Fe/Al/Ni 8/7/5)-NH2. With fast kinetics, high adsorption capacity, wide applicability and good stability, CMOF(Fe/Al/Ni 8/7/5)-NH2 may be an effective adsorbent for many other ionic organic pollutants.