Adsorption Of Organic Dyes Research Articles

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

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

Sustainable Wastewater Treatment: Recent Progress in the use of Bio-Waste-Derived Adsorbents for Organic Dye Removal

There are serious health and environmental hazards associated with the growing amount of organic dyes in wastewater from sectors like food processing, leather, and textiles. These pollutants are frequently ineffectively removed by traditional wastewater treatment techniques. Adsorbents made from bio-waste have become a viable substitute because of their high removal efficiency, affordability, and sustainability. The adsorption of organic dyes is facilitated by the distinct surface chemistries of these adsorbents, which are made from a variety of biomass sources. Through synthesis and modification approaches, recent research has concentrated on enhancing these materials' adsorption capacity, selectivity, and overall performance. Adsorbents made from bio-waste have potential uses in pollutant degradation, nutrient recovery, and value addition in addition to dye removal. But issues like leaching and long-term stability need to be carefully thought out. This review highlights the recent advancements in the application of bio-waste-derived adsorbents for organic dye removal from wastewater, emphasizing their potential contributions to sustainable wastewater treatment and resource recovery.

Enhancement of visible light adsorption and photocatalytic degradation activity of organic dye by coating semiconducting TiO2 shell on plasmonic Au particles

The plasmonic effect enhances light absorption in semiconductor photocatalysts, while the noble metal-semiconductor interface promotes charge carrier transfer and separation, boosting photocatalytic activity. However, current methods for synthesizing metal-core TiO2-shell nanoparticles face challenges, such as keeping stable and preventing aggregation. This study presents a simple and moderate synthesis method for Au@TiO2 core-shell nanoparticles, enabling precise control over the TiO2 shell thickness and stable photocatalytic performance. Various characterization techniques were employed to assess the optical and structural properties of the synthesized Au@TiO2 core-shell nanostructures. The results demonstrated that increasing the Au core concentration led to a gradual decrease in TiO2 shell thickness. The adsorption properties and photocatalytic degradation efficiency of the synthesized Au@TiO2 core-shell nanostructured catalysts were thoroughly examined, particularly focusing on their performance with methyl orange (MO) and methylene blue (MB). Au@TiO2 achieved excellent adsorption performance for MO, with a maximum capacity of 231±6 mg/g. Furthermore, Au@TiO2 exhibited higher photocatalytic degradation activity of both MO and MB than pure TiO2. The mechanism study indicated that it attributed to enhanced visible light absorption, reduced bandgap, and higher valence band energy. Additionally, the Au@TiO2 catalysts showed good cyclic stability, making them promising for future applications. This research offers insights into designing efficient photocatalysts, addressing existing synthesis challenges, and contributing valuable references for future advancements.

Two novel 3D polyoxometalate-based metal–organic frameworks for structure-directed selective adsorption and photodegradation of organic dyes

Degradation of organic dyes from industrial wastewater is crucial for human health and ecological balance. Synergy adsorption and photodegradation is one of the effective methods to degrade organic dyes at present. The former is usually limited by the challenge of its the recovery and the poor adsorption capacity of the adsorbent, whereas the latter frequently suffers from sluggish reaction kinetics. Herein, the introduction of the unique electron-rich Keggin polyoxometalates (CuW12 and SiW12) into electron-deficient metal photosensitive viologen framework to construct two polyoxometalate(POM)-based metal organic frameworks (POMOFs) of 3D porous layered structures, namely [Cu2(ipbp)2(H2O)2][CuW12O40]·3H2O (1) and [Co2(H2ipbp)3(H2O)2(CoO6)2][SiW12O40]·H2O (2); (H2ipbp·Cl = 1-(3,5-dicarboxyphenyl)-4,4′-bipyridinium), which enable selective adsorption of methylene blue (MB) and effectively photocatalytic degradation cationic dyes. In addition, POMs and metal-organic frameworks act in synergy to result in much improved adsorption of certain cationic dyes as well as enhanced photocatalytic activity that allow the catalyst to show better excellent reusability and stability. The adsorption degradation rate of MB and rhodamine B (RhB) of 2 is faster than that of 1 because of the lower Zeta potential of 2 suggesting that there are electrostatic interactions in the adsorption process. This work adopted a novel view to comprehening the technology.

Revisiting oxidation and reduction reactions for synthesizing a three-dimensional hydrogel of reduced graphene oxide.

An improvement to Hummers' method involving a cascade-design graphite oxidation reaction is reported to optimize safety and efficiency in the production of graphite oxide (GrO) and graphene oxide (GO). Chemical reduction using highly alkaline ammonia solution is a novel approach to synthesizing reduced graphene oxide (RGO). In this original research, we revisit the oxidation and reduction reactions, providing significant findings regarding the synthetic pathway to obtain a bioinspired water-intercalated hydrogel of RGO nanosheets. Influential factors in the graphite oxidation reaction, typically the exothermic reaction temperature and hydrogen peroxide effect, are described. Furthermore, the chemical reaction of GO reduction using highly alkaline ammonia solution (pH 14) was investigated to produce hydrated RGO nanosheets assembled in a hydrogel structure (97% water). Three-dimensional assembly and water intercalation are key to preserve the non-stacking state of RGO nanosheets. Therefore, ultrasound transmission to aqueous channels in the macroscopic RGO hydrogel vibrated and dispersed the RGO nanosheets in water. Analytical results revealed the single-layer nanostructures, functional groups, optical band gaps, optimized C/O ratios, particle sizes and zeta potentials of GO and RGO nanosheets. The reversible self-assembly of RGO hydrogels is essential for many applications, such as RGO coatings and polymer/RGO nanocomposites. In a water purification application, the RGO hydrogel was dispersed in aqueous solution by simple agitation and showed a high capacity for organic dye adsorption. After the adsorption, the RGO/dye particles were easily removed by filtration through ordinary cellulose paper. The process of adsorption and filtration is effective and inexpensive for practical environmental remediation. In summary, a bioinspired structure of RGO hydrogel is conceptualized for prospective nanotechnology.

Highly porous carbon with rich inherent groups for ultrahigh adsorption of organic dyes from wastewater

Activated carbon from renewable biomass or its waste to purify various dyeing wastewater from textile industry is highly desired. In this work, porous activated carbon was prepared by using silk waste as precursor via a simple one-step carbonization process. The obtained SWC-1-800 had ultrahigh adsorption for anionic dye AR73 and cationic dye MB owing to its ultrahigh specific surface area (2774 m2 g−1) and rich functional groups. SWC-1-800 had an increased adsorption capacity reaching 1310 and 928 mg g−1 for AR73 and MB respectively as the initial concentration up to 1000 mg L−1. Moreover, the adsorption capacity was stable under a wide range of Na+ and SDS concentration. By adjusting the temperature and pH value, the maximum adsorption capacity reached 1337 and 1000 mg g−1 for AR73 and MB respectively, keeping the removal rate of AR73 and MB more than 80 % after 5 adsorption cycles. Besides, SWC-1-800 demonstrated quite good adsorption ability for many other kinds of dyes, which adsorption capacity as high as 1998 mg g−1 (Rh B). The adsorption mechanism was further proposed according to the structural characteristics, inherent functional groups and adsorption properties. Using silk waste-derived carbon to effectively absorb the harmful dyes in the wastewater shows dual value for cleaner production via a “waste-waste to clean products” model, which has great application potential in dyeing wastewater purification.

Zirconium-based mixed ligand metal–organic framework for efficient adsorption of organic dyes

Zirconium-based mixed ligand metal–organic framework for efficient adsorption of organic dyes

Post-synthetic modification of zirconium-based metal-organic frameworks for enhanced simultaneous adsorption of heavy metal ions and organic dyes

Heavy metal and dye pollution pose a serious threat to human health and ecology, and there is an urgent need to develop novel adsorbent materials for wastewater treatment. In this study, a novel functionalized zirconium-based MOF UiO-66-Gd was prepared by a post-synthetic modification strategy and used for the simultaneous removal of Pb2+, Cu2+ and methylene blue (MB) from wastewater. UiO-66-Gd retained the crystalline structure and morphological features before modification. The specific surface area reached 574.94 m2/g, which can provide abundant active sites for adsorption. The effects of several factors on the adsorptive performance of UiO-66-Gd were investigated by batch adsorption experiments. The adsorption of Pb2+ by UiO-66-Gd reached the adsorption equilibrium in only 5 min. The theoretical maximum adsorption capacities for Pb2+, Cu2+ and MB were 833.33, 354.61 and 564.91 mg/g, respectively. In addition, UiO-66-Gd has excellent anti-interference and regeneration properties with potential for practical applications. Competition adsorption experiments showed that UiO-66-Gd had the greatest affinity for Pb2+. The adsorption of UiO-66-Gd on Pb2+ and Cu2+ was mainly through electrostatic interactions and chelation, and on MB mainly through electrostatic interactions, π-π interactions and hydrogen bonding. Overall, UiO-66-Gd has great potential for application in the removal of Pb2+, Cu2+ and MB.

Some aspects of adsorption, catalytic and photocatalytic interactions of organic dyes with TiO2-based binary nanocomposites

Some aspects of adsorption, catalytic and photocatalytic interactions of organic dyes with TiO2-based binary nanocomposites

Highly efficient malachite green adsorption by bacterial cellulose and bacterial cellulose/locust bean gum composite

In this study, bacterial cellulose (BC) and BC/locust bean gum (LBG) composite produced from banana hydrolysate were both used as the adsorbent for various organic dyes adsorption especially for malachite green (MG) adsorption for the first time. The BC/LBG(2%) composite exhibited significantly enhanced swelling rate and textural characteristics while maintained the basic structure of BC as depicted by XRD, FT-IR, and NMR, providing a foundation for its application as an excellent adsorbent. The composite exhibited a high adsorption rate and adsorption capacity for MG (exceeding 95 % and 2000 mg/g), and had a good selectivity for MG adsorption in the solution containing crystal violet (CV), rhodamine B (RB), and methyl orange (MO). The MG adsorption process conformed to multiple models including Langmuir and pseudo-first-order models. And the adsorption mechanism mainly comprised chemical adsorption (hydrogen bonding and electrostatic interactions) and physical adsorption. The reusability of BC/LBG(2%) composite was attractive for industrial application that the MG adsorption rate reduced merely a little (still higher than 88 %) after the 5th regeneration process. Overall, considering its adsorption capacity, selectivity, and reusability, BC/LBG(2%) composite prepared by in-situ fermentation with LBG addition was a competent adsorbent for MG adsorption and MG containing wastewater treatment.

Preparation of Sulfonate-Grafted Tetraphenylethylene-Based Hyper-Cross-Linked Polymers for Efficient Adsorption of Organic Dyes in Aqueous Solutions

Preparation of Sulfonate-Grafted Tetraphenylethylene-Based Hyper-Cross-Linked Polymers for Efficient Adsorption of Organic Dyes in Aqueous Solutions

High adsorption capacities for dyes by a pH-responsive sodium alginate/sodium lignosulfonate/carboxylated chitosan/polyethyleneimine adsorbent

Dyes are indispensable for the rapid development of society, but untreated dye wastewater can threaten human health. In this study, an adsorbent (SA/SL/CCS/PEI@MNPs) was synthesized by one-pot method using magnetic nanoparticles (MNPs), sodium alginate (SA), sodium lignosulfonate (SL), carboxylated chitosan (CCS) and polyethyleneimine (PEI). The adsorbent was mesoporous micrometer-sized particles with pore size of 34.92 nm, which was favorable for dynamic column experiments. SA/SL/CCS/PEI@MNPs possessed pH-responsive performance. Under acidic condition, the maximum adsorption capacities for anionic dyes (tartrazine, reactive black-5, indigo carmine) reached >550 mg/g. Under alkaline condition, those for cationic dyes (methylene blue, methyl violet, neutral red) exceeded 1900 mg/g. The function of the various modifiers was investigated. The results indicated that the incorporation of SL, CCS and PEI was able to provide plenty of sulfonate, carboxylate and amino/imine reactive groups so that adsorption capacities of dyes were improved. The adsorption mechanism was explored by FTIR and XPS. At the same time, the adsorption mechanism was more deeply analyzed using molecular dynamics simulations and radial distribution function. It was demonstrated that the dyes adsorption on the SA/SL/CCS/PEI@MNPs was mainly due to electrostatic attraction and π-π interaction. In addition, the adsorbent had good reusability, and the removal still reached over 90 % after five cycles. In conclusion, the adsorbent displayed a broad prospect for the adsorption of organic dyes.

Highly Porous Multiwalled Carbon Nanotube-Foam Composite for Batch Adsorption Performances of Dyes.

Treatment of dye pollutants prior to their release into the environment remains a formidable challenge, persisting as a longstanding issue. This study focuses on the development of a multiwalled carbon nanotube-foam (MWCNT-foam) composite through low-temperature chemical fusion (LTFC), resulting in a composite with a remarkably high accessible surface area (>475 m2 g-1). The MWCNT-foam composite exhibits a three-dimensional porous structure and demonstrates a notable affinity for organic dye adsorption. The efficacy of this composite was evaluated against various cationic dyes such as Methylene blue (MB) and Crystal Violet (CV) as well as anionic dyes such as Congo red (CR) and Eriochrome black T (EB), and the composite showed removal rates exceeding 99%. Furthermore, the study delved into the impact of the initial dye concentration, adsorbent dosage, kinetics, and other factors on the performance of the MWCNT-foam composite. The adsorption process achieved equilibrium in 10 min and strongly correlated with the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity of MWCNT-foam for MB, CV, CR, and EB was found to be 168.63, 147.49, 99.50, and 93.11 mg g-1, respectively. In order to showcase the potential of this material for continuous adsorption, a specialized cartridge was designed and employed to treat dye solutions, demonstrating the feasibility of continuous mode adsorption.

Liquid-Crystalline Photonic Sandwich: Electroresponsive Colloids of Clay Nanosheets Loading Photofunctional Dyes.

Colloidal clay nanosheets obtained by the delamination of layered crystals of smectite-type clay minerals in water form liquid crystals because of their shape anisotropy. Loading of organic dyes onto the liquid crystalline clay nanosheets will enable novel photonic materials, where photofunctions of the loaded dye are controlled by the liquid crystallinity of the clay nanosheets. However, adsorption of organic dyes onto the nanosheets renders the nanosheet surfaces hydrophobic, and consequently, colloidal stability of the nanosheets is lost. In this study, this drawback is overcome by sandwiching cationic stilbazolium dyes between a pair of synthetic fluorohectorite nanosheets. This is realized by the preparation of stilbazolium-clay second-stage intercalation compounds characterized by intercalation of dye cations into every other interlayer space of the hectorite clay, where nonintercalated interlayer spaces are occupied by Na+ ions. The second-stage intercalation compounds are obtained by partial ion exchange of mother clay mineral incorporating Na+ ions in all of the interlayer spaces and delaminated from the Na+-containing interlayer spaces to form clay nanosheets sandwiching the dye molecules. Aqueous colloids of the dye-sandwiching clay nanosheets form colloidal liquid crystals, and the dye-sandwiching liquid crystalline clay nanosheets respond to an applied AC electric field to be aligned parallel to the electric field. The assembled structure of the dye-sandwiching clay nanosheets under the electric field is characterized by aligned discrete clay platelets, which is somewhat different from that of a colloidal liquid crystal of clay nanosheets without dye loading characterized by macroscopic liquid crystalline domains up to submillimeters. The electric alignment of the clay nanosheets induces alteration of light absorption of the sandwiched stilbazolium molecules, which verifies a strategy of constructing stimuli-responsive photonic materials of clay-organic hybrids.

Assembly of 3D printed N-doped biochar as impeller with CaCO3 as sacrificial pore generator for enhanced dye adsorption

Three-dimensional (3D) printed monolithic catalysts/adsorbents have attracted much attention due to their excellent properties. Herein, the rice husk-derived nitrogen-doped biochar (using urea as the nitrogen dopant) was printed into monolithic adsorbents using direct ink writing technology, and then assembled as agitating paddles for organic dye adsorption. To reduce the over-embedding of active sites in the polymeric matrix, CaCO3 particles in nano-sized or micron-sized were added as sacrificial pore generators to form macropores and expose active sites, leading to an enhanced mass transfer efficiency. Material characterization results confirm the self-sacrificial role of CaCO3. The 3D-printed adsorbents with micron-sized CaCO3 (denoted as 3D-HRSCCm) possessed excellent adsorption performance, as evidenced by a high adsorption capacity and kinetics study. Meanwhile, 3D-HRSCCm adsorbents were mounted as agitating impellers which demonstrated excellent reusability with the adsorption efficiency remaining above 90% after ten cycles. Furthermore, the 3D-HRSCCm exhibited excellent adsorption properties for various dyes such as methylene blue, rhodamine B, crystal violet, and malachite green. Moreover, the numerical simulation confirms that the introduction of CaCO3 as a pore generator improved diffusion by providing wider channels and facilitated the mass transfer that accelerated the adsorption rates.

High-capacity adsorption of organic dyes using separable pullulan gel encapsulated with PDA-modified ZIF-8

In this investigation, a hydrogel adsorbent featuring remarkable efficiency in dye adsorption was successfully synthesized by the integration of natural polysaccharide (pullulan) and nanoparticles (ZIF-8@PDA). The prepared natural polysaccharide nanocomposite hydrogels not only exhibit superior mechanical strength and biocompatibility, but also demonstrate adeptness in the removal of dye pollutants. The dye removal capacities were 615.4 mg/g for malachite green (MG) and 525.8 mg/g for Congo red (CR), respectively. Notably, the adsorption process exhibits minimal susceptibility to variations in water quality and the presence of co-existing ions. The pH-responsive surface charge conversion capability of the adsorbent renders it recyclable, maintaining a dye adsorption performance exceeding 88 % even after 5 cycles of repeated usage. Overall, these environmentally friendly natural polysaccharide nanocomposite hydrogels hold potential for addressing complex wastewater treatment challenges and long-term use.

Self-Assembly of Polynuclear Coordination Cage and Organic Dyes Adsorption Behavior in Water

Self-Assembly of Polynuclear Coordination Cage and Organic Dyes Adsorption Behavior in Water

Exploring the multifunctionality of MoS2 and MoSe2 nanostructures: Enhanced ammonia sensing, antimicrobial activity and organic dye adsorption

Nanostructured materials have emerged as a focal point in materials science, primarily due to their unique physical and structural characteristics that facilitate a wide range of applications. Multifunctional activity derived from a single material has been attracting attention recently. This study focuses on synthesizing the Molybdenum disulfide (MoS2) and Molybdenum diselenide (MoSe2) using the hydrothermal method of synthesis. The nanostructures thus produced were studied for various environmental remediation applications, including ammonia gas sensing, antimicrobial activities, and the removal of methyl orange (MO) dye from aqueous solutions. Herein, the flower-like MoS2 nanostructures exhibit remarkable ammonia-sensing capabilities with a response (Δ R/Rair%) of 100 % at room temperature when exposed to 20 ppm of ammonia gas. Additionally, they were also effective in the removal of MO from aqueous solutions. Furthermore, the antimicrobial activity of the synthesized samples was also studied against Escherichia Coli (E. Coli) (MTCC443) and Saccharomyces cerevisiae (MTCC170) using the agar diffusion method. The antibacterial activity of MoS2 and MoSe2 against E. coli produced inhibition zones of 18 mm and 22 mm, respectively. The antifungal activity against Saccharomyces cerevisiae resulted in inhibition zones of 11 mm and 16 mm, respectively, for 0.1 μg of MoS2 and MoSe2. The results indicated that MoSe2 exhibits superior antibacterial and antifungal activities compared to MoS2. This enhanced activity is likely attributable to the nanorod-like morphology of MoSe2, which facilitates easier penetration into microbial cell walls. Overall, this study underscores the multifunctional potential of these synthesized nanostructured materials, highlighting their applicability in environmental remediation.

Adsorbent based on MOF-5/cellulose aerogel composite for adsorption of organic dyes from wastewater

Industries persistently contribute to environmental pollution by releasing a multitude of harmful substances, including organic dyes, which represent a significant hazard to human health. As a result, the demand for effective adsorbents in wastewater treatment technology is steadily increasing so as to mitigate or eradicate these environmental risks. In response to this challenge, we have developed an advanced composite known as MOF-5/Cellulose aerogel, utilizing the Pampas plant as a natural material in the production of cellulose aerogel. Our investigation focused on analyzing the adsorption and flexibility characteristics of this novel composite for organic dye removal. Additionally, we conducted tests to assess the aerogel’s reusability and determined that its absorption rate remained consistent, with the adsorption capacity of the MOF-5/cellulose aerogel composite only experiencing a marginal 5% reduction. Characterization of the material was conducted through XRD analysis, revealing the cubic structure of MOF aerogel particles under scanning electron microscopy. Our study unequivocally demonstrates the superior adsorption capabilities of the MOF-5/cellulose aerogel composite, particularly evident in its efficient removal of acid blue dye, as evaluated meticulously using UV–Vis spectrophotometric techniques. Notably, our findings revealed an impressive 96% absorption rate for the anionic dye under acidic pH conditions. Furthermore, the synthesized MOF-5/cellulose aerogel composite exhibited Langmuir isotherm behavior and followed pseudo-second-order kinetics during the absorption process. With its remarkable absorption efficiency, MOF-5/cellulose aerogel composites are poised to emerge as leading adsorbents for water purification and various other applications.

A pH-dependent and charge selective covalent organic framework for removal of dyes from aqueous solutions

A novel imine-linked COF is synthesized by the condensation of 2,4,6-tris(4-aminophenyl)−1,3,5-triazine (TAPT) and 2-hydroxy-5-methoxyisophthalaldehyde (HMIPA) under solvothermal conditions. This COF adsorbs preferentially the neutral dye Neutral Red (NR) over the positively charged dye Methylene Blue (MB) at pH 7, and the negatively charged Methyl Orange (MO) over the positively charged Methylene Blue (MB) at pH 3. The maximum adsorption capacities (qe) obtained within very short times (11–60 min) under optimized conditions were 108, 185 and 429 mg.g−1 for the MB, MO, and NR dyes, respectively. These adsorptions obey the Langmuir isotherm and pseudo-second-order kinetics. The prepared TAPT-HMIPA-COF is used successfully for the removal of the dyes from real water and treated wastewater samples. The adsorption data, BET, FTIR, and zeta potential measurements show that the electrostatic, π-π stacking and hydrogen bond interactions are responsible for the adsorption of organic dyes on the surface of the prepared COF. Due to recyclability, high capacity and efficiency for the adsorption of positive, negative and neutral organic dyes, this COF can be considered promising for simultaneous removal of various dyes from aqueous solutions at adjusted pHs.