Efficient Removal Of Organic Dyes Research Articles

Upcycling of PVC waste to high-value sorbent with KOH-activation for efficient removal of organic dyes

Polyvinyl chloride (PVC), known for its chemical stability and flame-retardant qualities, has many uses in various fields, such as pipes, electric wires, and cable insulation. Research has established its potential recovery as a fluidic fuel through pyrolysis, but the use of PVC pyrolysis oil, which is tainted by chlorine, is constrained by its low heat value and harmful environmental effects. This study engineered a layered double hydroxide (LDH) to tackle these challenges. The LDH facilitated dechlorination during PVC pyrolysis and bolstered thermal stability via cross-linking. During pyrolysis with LDH, PVC was transformed into carbon-rich precursors to sorbents. Chemical activation of these residues using KOH created sorbents with a specific surface area of 1495.4 m2 g⁻1, rendering them hydrophilic. These resulting sorbents displayed impressive adsorption capabilities, removing up to 486.79 mg g⁻1 of methylene blue and exhibiting the simultaneous removal of cations and anions.

Design of novel FeSe2/ZnO composites and their application in photodegradation of methylene blue

Water pollution has become one of the major global issues, posing serious threat to both humans and aquatic life. The elimination of organic industrial pollutants from wastewater is currently a major area of research. Herein, we report for the first time a novel FeSe2/ZnO composite system for highly efficient removal of organic dyes under visible light. FeSe2/ZnO composites with varying mass ratios of FeSe2 were successfully prepared through simple and low-cost chemical method. The physiochemical properties of the prepared FeSe2/ZnO composites were carefully evaluated and compared with those of pure ZnO rods and FeSe2 flowers. UV–vis spectroscopy confirmed that the coupling of FeSe2 with ZnO caused a significant improvement in the optical absorption of ZnO. The bandgap energies of FeSe2/ZnO composites showed a red shift with increasing the ratio of FeSe2 flowers. The prepared samples were evaluated for their photocatalytic response against the removal of methylene blue dye. Compared to the pure FeSe2 and ZnO, the composites displayed impressive photocatalytic performance. Among the prepared samples, composite with an optimum ratio of 75 wt% FeSe2 revealed outstanding photocatalytic efficiency, making it a promising candidate for the removal of organic pollutants.

Carbon encapsulated ZnO nanoplates for efficient removal of organic dyes from aqueous medium by adsorption: Role of organic ligand and calcination temperature

Water pollution by organic dyes poses great challenge to the environment as well as living organisms. Herein, we have fabricated nanoplates of ZnO in carbon matrix by controlled calcination of zinc-metal organic frameworks (Zn-MOFs) and used as adsorbents for efficient removal of organic dyes from water. Zn-MOF of phthalic acid and 5-nitrophthalic acid produced nanoplates of ZnO (ZnO-C and ZnO-NC) in carbon matrix without and with nitrogen doping. The fabricated hybrid nanostructures were characterized using PXRD, FTIR, BET, TGA, HR-SEM, HR-TEM and XPS analysis. Both ZnO-C and ZnO-NC showed high adsorption of cationic dyes (crystal violet (CV), methylene blue (MB) and Rhodamine B (Rh B)) compared to anionic dyes (methyl orange (MO) and Eosin yellow (EY)). Nitrogen doped ZnO-NC exhibited relatively higher percentage of dyes removal (99 %) compared to ZnO-C. Interestingly, ZnO-NC showed high adsorption of MB dye across the pH range from acidic (pH = 3.0) to alkaline (pH = 11.0). The zero-point charge indicated the negative surface charge for ZnO-NC/ZnO-C that facilitated electrostatic interactions between dyes and adsorbents. Adsorption kinetics suggested a pseudo second order model and adsorption isotherm fitted well with the Freundlich model, suggesting heterogenous adsorption with multilayer coverage of dye molecules. The reusability of ZnO-NC showed only slight reduction of adsorption in three successive cycles. Further, ZnO-NC was used as column packing materials for the successful removal of both cationic as well as anionic dyes upon filtration. Thus, the present studies provided insight on the organic ligand structure and calcination temperature of MOFs for transforming them into effective organic dye adsorbent.

Urchin-like CO2-responsive magnetic microspheres for highly efficient organic dye removal

CO2-responsive materials have emerged as promising adsorbents for the remediation of refractory organic dyes-contaminated wastewater without the formation of byproducts or causing secondary pollution. However, realizing the simultaneous adsorption−separation or complete removal of both anionic and cationic dyes, as well as achieving deeper insights into their adsorption mechanism, still remains a challenge for most reported CO2-responsive materials. Herein, a novel type of urchin-like CO2-responsive Fe3O4 microspheres (U-Fe3O4 @P) has been successfully fabricated to enable ultrafast, selective, and reversible adsorption of anionic dyes by utilizing CO2 as a triggering gas. Meanwhile, the CO2-responsive U-Fe3O4 @P microspheres exhibit the capability to initiate Fenton degradation of non-adsorbable cationic dyes. Our findings reveal exceptionally rapid adsorption equilibrium, achieved within a mere 5 min, and an outstanding maximum adsorption capacity of 561.2 mg g−1 for anionic dye methyl orange upon CO2 stimulation. Moreover, 99.8% of cationic dye methylene blue can be effectively degraded through the Fenton reaction. Furthermore, the long-term unresolved interaction mechanism of organic dyes with CO2-responsive materials is deciphered through a comprehensive experimental and theoretical study by density functional theory. This work provides a novel paradigm and guidance for designing next-generation eco-friendly CO2-responsive materials for highly efficient purification of complex dye-contaminated wastewater in environmental engineering.

Biologically inspired Co-MOF as catalase mimics with an unexpected ROS production ability for the efficient removal of organic dyes

Developing an efficient advanced oxidation technology is of great significance for water treatment and environmental protection. Here, inspired by the structure and feature of coenzyme B12 in natural enzymes (cleavage of Co-C bond triggers the generation of radical), a Co based metal-organic framework (Co-MOF) with catalase-mimicking activity was synthesized and applied in the degradation of organic dyes. Firstly, Co-MOF nanozyme was fabricated via the coordination self-assembly strategy at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive scanning (EDS), powder X-ray diffraction (PXRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphology and structure. The results showed that the obtained Co-MOF nanozyme was rhombic dodecahedral morphology with a size of ∼ 500 nm and excellent crystallinity. The enzymatic experiments proved that such nanozyme possessed a single catalase-like activity. Further research results demonstrated that Co-MOF-based degradation process of acid fuchsin (AF) or crystal violet (CV) had excellent pH adaptability (pH > 5.0). Unexpectedly, an ultra-high catalytic degradation rate (211.35 min−1 g−1 L) was successfully achieved in the catalytic degradation of AF, and it was approximately 5∼200 times of the previous optimal nanozyme or catalysts. In complex matrices and real wastewater, this catalytic process could still maintain degradation efficiency above 90% or even higher within 5 minutes, proving its excellent stability and adaptability. The results of radical and electron quenching experiments, electron paramagnetic resonance (EPR), and electrochemical analysis demonstrated that the excellent catalytic degradation performance was attributed to the generation of reactive oxygen species (ROS) (∙O2 was the main contributor) and the existence of electron transfer. In summary, this new catalytic property endows Co-MOF nanozyme with considerable potential for dye degradation, extending the application scope of catalase mimics.

Fast and highly efficient removal of organic dyes from aqueous solution by attapulgite modified with different amino groups

Type of functional groups of the adsorbent is crucial for an adsorption process which significantly affects adsorption rate and adsorption capacity for certain adsorbate. In this study, attapulgite (APT) was modified with different amino groups and the adsorbents obtained were used to remove toxic organic dyes from aqueous solution. Five adsorption kinetic models and three adsorption isotherm models were employed to estimate the adsorption behaviors for organic dyes methylene blue (MB) and Congo red (CR) onto the adsorbents. The results showed that adsorption behaviors of the adsorbents for MB were different from those for CR, and among the four adsorbents, APT exhibited the highest adsorption capacity for MB (307.27 mg/g) while APT modified with hyperbranched polyamide-amine (APT-(3)) had the highest adsorption capacity for CR (1277.33 mg/g) according to adsorption kinetic data, indicating the type of amino groups did have a significant impact on adsorption. It can be concluded that APT-(3) exhibited certain adsorption selectivity for CR. In addition, the adsorption of MB and CR was a fast and highly efficient process. The results indicated that the APT samples used can remove and enrich cationic and anionic dyes and can be potentially used in the wastewater treatment.

Wheat flour-derived amyloid fibrils for efficient removal of organic dyes from contaminated water

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.Graphical

Porous organic polymers incorporating BODIPY moieties for efficient removal of organic dyes from aqueous solutions

The incorporation of BODIPY units into porous frameworks enhances the materials’ ability to efficiently adsorb organic dyes from aqueous solutions.

Multi-crosslinked robust alginate/polyethyleneimine modified graphene aerogel for efficient organic dye removal

Polymer composite aerogel holds great promise for sewage treatment. Here, a novel triply crosslinked alginate/graphene aerogel for efficient organic dye removal was reported. The triple crosslinking of aerogel was realized firstly by the association between in-situ released Ca2+ ions and sodium alginate (SA). And the electrostatic attraction between polyethyleneimine-modified reduced graphene oxide (PEI-RGO) and the alginate chain provides an additional boost to crosslinking the aerogel. Moreover, the hydrogen bonding between PEI and SA also helps in achieving the crosslinking of the aerogel. Thus, the robust triply crosslinked alginate/graphene aerogel was obtained with using cost-effective precursors and a straightforward process. Additionally, the as-prepared aerogels were employed to remove the cationic dyes from wastewater. It was found that the porous alginate/graphene exhibited a strong affinity to methylene blue (MB) and neutral red (NR). The adsorption process of the aerogel towards MB was in accordance with the Langmuir isothermal model and pseudo-second-order model, and the maximum theoretical adsorption capacities were 1091.9 and 813.2 mg g−1, suggesting its potential application in sewage treatment.

Efficient removal of organic dyes using electrospun nanofibers with Ce-based UiO-66 MOFs

Cerium-based UiO-66 (Ce-UiO-66) metal-organic frameworks (MOFs) were synthesized via a facile solvothermal method and fully characterized using FTIR, XRD, BET, SEM, EDX, and zeta potential techniques. The synthesized Ce-UiO-66 particles were embedded into an electrospun cross-linked polyvinyl alcohol (PVA)/chitosan (CTS) nanofiber (EPCNF), and then employed to remove organic dyes from water. The adsorption results demonstrated that the adsorption capacities of both anionic (Congo Red (CR), Methyl Orange (MO) and Methyl Red (MR)) and cationic (Methylene Blue (MB)) dyes over the fabricated electrospun nanofibers (ENFs) increased with increasing the loadings of Ce-UiO-66 MOFs. Accordingly, the adsorption performance of EPCNF-10 (containing 10 wt% of Ce-UiO-66 MOFs) adsorbent toward these organic dyes is in the order of CR (102.04 mg/g) > MO (87.71 mg/g) > MR (65.35 mg/g) > MB (34.24 mg/g). Moreover, it was found that the Freundlich isotherm model and the pseudo-second-order kinetic model were appropriate for describing the adsorption behaviors of EPCNF-10 adsorbent toward both anionic and cationic dyes. Thus, it can be proposed that the fabricated EPCNF-10 adsorbent would be effective adsorbent materials for the removal of anionic and cationic dyes from water due to its excellent adsorption performance, facile preparation, good regeneration, and simple separation from aqueous solutions.

A novel Fe-containing carbon foam with hierarchical porous structure for efficient removal of organic dyes

A novel Fe-containing carbon foam (Fe-CF) was achieved with a hierarchical porous structure by carbonization of nano‑magnesium oxide/epoxy resin mixture followed by Fe(NO3)3 activation. The structures and properties of as-prepared Fe-CF were characterized via XRD, compression strength test, FESEM, TEM, BET, Raman and XPS, meanwhile the effects of adsorption conditions on the removal performance of Congo red (CR), Malachite green (MG) and Methylene blue (MB) by the Fe-CF are investigated through batch adsorption experiments. Results show that the Fe-CF obtained at 1000 °C possesses a fluffy and porous structure without obvious collapse and closure, and the iron oxide particles are evenly distributed on its surface, which endows it with high adsorption capacities for CR (1263.36 mg g−1), MG (679.84 mg g−1) and MB (483.66 mg g−1) at the optimum conditions, respectively. Furthermore, the adsorption process can be depicted well by the Langmuir and pseudo-second-order models, and the thermodynamic analysis results reflect that the adsorption processes are thermodynamically feasible and spontaneous. More importantly, the prepared adsorbent retains relatively high adsorption ability and stability even after five regeneration cycles.

Magnetic Mesoporous Silica Nanoparticles Functionalized with 5,5′-Dithiobis(2-Nitrobenzoic Acid) for Highly Efficient Removal of Organic Dyes from Contaminated Water

The removal of organic pollutants has become an increasingly important environmental concern. In recent years, there has been significant research into the use of nanomaterials for removing organic dyes in single-component systems. In this study, magnetic mesoporous silica nanoparticles (magnetic MSNs) were prepared with an average particle size of 170 nm. Iron oxide nanoparticles (20 nm) were embedded within the mesoporous silica structure. These nanoparticles were functionalized with amine, derivatized with thiol, and then reacted with 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB). The presence of DTNB molecules attached to the surface was confirmed by FTIR spectra, as evidenced by the appearance of peaks at ∼1528 cm−1 and ∼1365 cm−1. The nanoadsorbents demonstrated high removal efficiency for bromothymol blue (BT) and methyl orange (MO) at a pH below 5, with a maximum adsorption capacity of 139.27 mg/g and 101.62 mg/g for BT and MO, respectively. The linear regression coefficient value suggested that the adsorption of BT and MO onto magnetic MSNs-DTNB followed the Langmuir isotherm and second-order process. Overall, these findings suggest that magnetic MSNs-DTNB could be a promising nanoadsorbent for removing organic pollutants from contaminated water sources.

β-Cyclodextrin network crosslinked by novel phosphonium-based tetrakiscarboxylic acid derived from PH3 tail gas: Synthesis and application for rapid removal of organic dyes from wastewater

Organic dyes, such as methyl orange (MO), Congo red (CR), crystal violet (CV) and methylene blue (MB), are common organic pollutants existing in wastewater. Therefore, the exploration of bio-based adsorbents for the efficient removal of organic dyes from wastewater has gained many attentions. Here, we report a PCl3-free synthetic method for the synthesis of phosphonium-containing polymers, in which the prepared tetrakis(2-carboxyethyl) phosphonium chloride-crosslinked β-cyclodextrin (TCPC-β-CD) polymers were applied to the removal of dyes from water. The effects of contact time, pH (1−11), and dye concentration were investigated. The selected dye molecules could be captured by the host-gest inclusion of β-CD cavities, and the phosphonium and carboxyl groups in the polymer structure would respectively facilitate the removal of cationic dyes (MB and CV) and anionic dyes (MO and CR) via electrostatic interactions. In a mono-component system, over 99 % of MB could be removed from water within the first 10 min. Based on the Langmuir model, the calculated maximum adsorption capacities of MO, CR, MB, and CV were 180.43, 426.34, 306.57, and 470.11 mg/g (or 0.55, 0.61, 0.96 and 1.15 mmol/g), respectively. Additionally, TCPC-β-CD was easily regenerated using 1 % HCl in ethanol, and the regenerative adsorbent still showed high removal capacities for MO, CR, and MB even after seven treatment cycles.

CoNi–MOF–Graphene Magnetic Nanocomposites for the Electrocatalytic Detection of Glucose and the Efficient Removal of Organic Dyes

The design of a nanocomposite with electrocatalytic activity and recyclable development for the detection of small biomolecules and the removal of environmental pollutants has received enormous attention. A magnetic nanocomposite was synthesized by the hydrothermal approach comprising two building units: metal–organic frameworks (MOFs) and graphene (GR). GR accumulated organic ligands through the large specific surface area and cobalt (Co) and nickel (Ni) served as coordination ions to seamlessly connect with the former for forming CoNi–MOFs–GR (CNMs–GR) to improve the conductivity of MOFs and the electrocatalytic activity of GR. The nanocomposite was utilized to construct an electrochemical sensing platform for the detection of glucose in human blood serum and the removal of organic dyes (methylene blue (MB), congo red (CR), and neutral red (NR)) in water. The CNMs–GR-modified electrode exhibited good electrochemical performance toward glucose in a wide linear range of 10–2900 μM with a detection limit of 1.27 μM. The maximum uptake capacity of CNMs–GR for MB, CR, and NR was 184.29, 912.47, and 894.36 mg/g, respectively. Most obviously, this work provided a strategy for the design of an effective bifunctional nanocomposite, which not only demonstrated the enormous potential for detection of glucose but also realized the removal of organic dyes.

Non-porous covalent organic polymers enable ultrafast removal of cationic dyes via carbonyl/hydroxyl-synergetic electrostatic adsorption

Rapid and highly efficient removal of organic dyes from polluted water is of great significance for environmental protection and water resources management. Herein, an anionic covalent organic polymer (COP), denominated as COPOH+CO, with the fastest cationic dye adsorption kinetics so far was prepared and packed into solid phase extraction cartridges for rapid and automatic water treatment. As-prepared COPOH+CO contains abundant hydroxyl and carbonyl groups. Compared to COPOH and COPCO, other two COPs containing only hydroxyl and carbonyl, respectively, COPOH+CO gives a maximum adsorption capacity of 813 mg·g−1 towards cationic dye methylene blue (MB), which is about 4.6 times the sum of those of COPOH (42.4 mg·g−1) and COPCO (135 mg·g−1), suggesting the existence of 1 + 1 > 2 synergy between carbonyl and hydroxyl groups. Such a synergy is well demonstrated by theoretical calculation, which shows that the mutual penetration distance of electrostatic potentials in MB/COPOH+CO complex (4.722 Å) is much larger than those in MB/COPOH (0.443 Å) and MB/COPCO (1.602 Å). Although the rapid synthesis endows COPOH+CO with very poor porosity, the resulted surface adsorption avoids the long-term mass transfer, thus giving an ultra-fast adsorption kinetics with a so far fastest adsorption rate constant of 0.17 g·mg−1·s−1. This work demonstrates that by using the synergetic effect of surface functional groups, rapidly synthesized non-porous COPs may work as promising adsorbents for fast adsorption of targets.

Adsorption-enhanced catalytic oxidation for long-lasting dynamic degradation of organic dyes by porous manganese-based biopolymeric catalyst

Improving the adsorption kinetics of metal-oxide catalysts is critical for the enhancement of catalytic performance in heterogeneous catalytic oxidation reactions. Herein, based on the biopolymer pomelo peels (PP) and metal-oxide catalyst manganese oxide (MnOx), an adsorption-enhanced catalyst (MnOx-PP) was constructed for catalytic organic dyes oxidative-degradation. MnOx-PP shows excellent methylene blue (MB) and total carbon content (TOC) removal efficiency of 99.5 % and 66.31 % respectively, and keeps the long-lasting stable dynamic degradation efficiency during 72 h based on the self-built continuous single-pass MB purification device. The chemical structure similarity and negative-charge polarity sites of the biopolymer PP improve the adsorption kinetics of organic macromolecule MB, and construct the adsorption-enhanced catalytic oxidation microenvironment. Meanwhile, the adsorption-enhanced catalyst MnOx-PP obtains lower ionization potential and O2 adsorption energy to promote the continuous generation of active substance (O2*, OH*) for the further catalytic oxidation of adsorbed MB molecules. This work explored the adsorption-enhanced catalytic oxidation mechanism for the degradation of organic pollutants, and provided a feasible technical idea for designing adsorption-enhanced catalysts for the long-lasting efficient removal of organic dyes.

Highly efficient removal of organic dyes and heavy metal cation from wastewater by polyphenolate porous coordination polymer

Highly efficient removal of organic dyes and heavy metal cation from wastewater by polyphenolate porous coordination polymer

Crosslinked 3D porous composite foams as adsorbents for efficient organic dye removal

Crosslinked 3D porous composite foams as adsorbents for efficient organic dye removal

3D flower-like CuO@NiAl-LDH microspheres with enhanced removal affinity to organic dyes: mechanistic insights, DFT calculations and toxicity assessment

Highly efficient removal of organic dyes in wastewater is attracting more and more attention.

Visible-light induced photocatalytic removal of methylene blue dye by copper oxide decorated zinc oxide nanorods

The establishment of rod-shaped visible light heterojunction ZnO/CuO composites for potential redox ability presents a potential application prospect in the development of efficient photocatalysts for environmental purification. Herein, the CuO-decorated ZnO nanorods composites with preeminent retrievability were obtained by the simple hydrothermal method. The physicochemical properties of the ZnO, CuO and its composites were explored through systematic characterizations. X-ray diffraction (XRD) results show that the ZnO belongs to the wurtzite structure and CuO belongs to the monoclinic crystal structure. The size, shape and elemental composition of the ZnO/CuO composites were confirmed by high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) analysis. The average length of the nanorods is around 420 to 430 nm and the diameter is around 24–30 nm, respectively. The synthesized CuO/ZnO composites were used as a photocatalyst for the degradation of methylene blue (MB) dye under UV–visible light irradiation (UV–Vis). Particularly, ZnO/CuO (10%) composites achieved 98.5% degradation within 150 min, thus evidence suggesting that ZnO/CuO (10%) composites exhibited the best catalytic activity at optimum photocatalytic conditions. The composite materials contain a synergistic effect/factor, which is positive interaction between the CuO and ZnO to improve the photocatalytic activity. In addition, ZnO/CuO (10%) composites demonstrated good reusability and stability while retaining their high photocatalytic activity. It was estimated that this study could create a new opportunity to fabricate easily recoverable and eco-friendly photocatalysts with nanosized heterojunction for efficient removal of organic dyes, antibiotic pollutants and pesticides etc under visible light irradiation.