Separation Of Dyes Research Articles

Development and evaluation of environmentally sustainable cenosphere ceramic membrane for the efficient separation of methylene blue dye

Development and evaluation of environmentally sustainable cenosphere ceramic membrane for the efficient separation of methylene blue dye

Interfacial lignin glued cellulose/aramid nanofiber membranes: Combing toughness, stability, and dye rejection performances

Nanoscale cellulose-based membranes have been considered as perfect candidates for organic dye separation attributed to their sustainability, high aspect ratio, and nanoscale designation. However, as natural polysaccharide, nanocellulose still suffers from drawbacks like brittleness and vulnerability. In this work, the tough and stable lignocellulose nanofibers (LCNFs) based composite membranes were fabricated by introducing lignin modified aramid nanofibers (DANFs) as reinforcing agents. Being benefit from the interfacial lignin bridging effects, the noncovalent interactions (e.g., H-bond and π-π stacking) between LCNFs and DANFs strengthened, and the resultant composite membranes presented enhanced tensile strength (∼186.9 MPa, 6.3 time higher than LCNFs membranes), toughness (∼9.28 MJ/m3, 105 time higher than LCNFs membranes), Young’s modulus (∼8.43 GPa, 4.6 time higher than LCNFs membranes), as well as the optimized stabilities (in organic, acidic and alkali conditions). Combing all these advantages, the composite membranes demonstrated promising dye rejection performances toward methyl violet (a reject rate of ∼98.54 % and a flux of ∼29.76 L•m−2•h−1•bar−1), and can removal 63.08 % of methyl violet after 10 recycles. Thus, this research paves a simple and efficient way to made strong LCNFs-based separation membranes that are suitable as dye separator in harsh environments.

High performance loose-structured membrane enabled by rapid co-deposition of dopamine and polyamide-amine for dye separation

Textile wastewater poses a significant environmental challenge that demands effective treatment. Membrane separation offers a promising solution, with high-flux tight ultrafiltration membranes recognized as an effective technology for dye separation. Polyamide amine (PAMAM), a dendritic macromolecule renowned for its regular structure, high monodispersity, excellent solubility, and tunable molecular weight, has emerged as a promising material for membrane fabrication. This study introduces a novel, eco-friendly, and time-efficient method for preparing polymer composite membranes through one-step co-deposition of dopamine (DA) and PAMAM, predominantly utilizing Michael addition and Schiff base reactions. The incorporation of ammine-rich PAMAM imparts ultra-high hydrophilicity to the membranes (contact angle of 38°), facilitating strong adhesion of water molecules to the membrane surface. The effects of co-deposition time and concentrations of DA and PAMAM on the separation performance of the resulting membranes were systematically investigated. Notably, the optimal membrane demonstrated a high water flux (126.1 L m-2h−1 bar−1), primarily due to the incorporation of PAMAM, which resulted in a looser selective separation layer. Furthermore, the membrane demonstrated excellent rejection of methyl blue (MB) at 98.9 % and low rejection os methyl orange (MO) at 13.2 %, making it well-suited for the selective separation of mixed dyes. Our approach offers a sustainable and technologically advanced solution for addressing resource recovery from textile wastewater.

Selective separation of dyes and tetracycline hydrochloride in polymer‐nucleotide coacervate droplets

AbstractThis paper reports the formation of coacervates by the electrostatic interaction of poly (diallyldimethylammonium chloride) (PDDA) and adenosine triphosphate (ATP) in aqueous solution, examining its formation conditions, stability, and efficiency in separation. The ideal concentration for creating coacervate droplets in pure water, HEPES buffer, and NaCl solution was determined to be 20 mM of PDDA and ATP. Enhancing the stability of coacervates was achieved by incorporating phospholipid vesicles on their surface, presenting a novel strategy for building cell models. Ostwald Ripening was employed to comprehend the growth mechanism of the coacervates, while the Hofmeister Ion Series and Schulze‐Hardy's rule were utilized to elucidate the stability differences in solutions containing NaCl, Na2SO4, and MgCl2. These coacervates were stable at concentrations below 90 mM NaCl, 200 mM Na2SO4, and 30 mM MgCl2, respectively. We also explored the specific separation of dyes and tetracycline hydrochloride (TC) in the coacervates. Separation efficiencies of 92.98% for methylene blue (MB), 94.19% for methyl orange (MO), and 85.94% for TC, were achieved by the coacervates, which can be attributed to the synergistic effects of hydrophobicity, electrostatic forces, and π‐π interactions. The proposed coacervates have great potential in cell mimicry and water treatment.

Low Fouling Molecular Selective Channels through Self-assembly of Cross-linked Block Copolymer Micelles for Selective Separation of Dye and Salt.

We report the solvent-evaporation and ionic cross-linking mediated self-assembly of the shell cross-linked micelles of the amphiphilic triblock copolymer containing middle poly(methyl methacrylate) block (hydrophobic) and poly(2-dimethylamino)ethyl methacrylate end blocks (hydrophilic) on the membrane substrate to create molecular selective channels. The formation of selective channels on the substrate is attributed to the local increase of micelle concentration upon solvent evaporation, which leads to the core-core hydrophobic interaction. The post-ionic cross-linking of the shell part further reduces the intermicelle distance, thereby creating interstices for selective separation. The TUF-1:1 membrane prepared by the self-assembly of the cross-linked micelles (triblock copolymer:halide-terminated PEG-based = 1:1 w w-1) and by the post-ionic cross-linking shows molecular weight cutoff of 3000 g mol-1 and pure water permeance of 52 L m-2 h-1 bar-1. The membrane shows 99.5-99.9% rejection of Congo red and Direct red-80 in the presence or absence of salts and Na2SO4 to dye separation factor of about 900. The added functionality (PEG) in the micelle structure provides good fouling-resistant properties toward dye and bovine serum albumin. This work provides the membrane formation mechanism and the advantages of the membrane for fractionation and resource recovery applications.

High Water Permeability Interfacial Polymerized PVDF/EAA Composite Nanofiltration Membrane for Dye Separation

High Water Permeability Interfacial Polymerized PVDF/EAA Composite Nanofiltration Membrane for Dye Separation

Graphene oxide-polydopamine loaded uniform fibrous membranes via robust multi-channel microfluidic-electrospinning method

The rapid development of modern industries has caused serious water pollution such as dyes wastewater, which brings environmental problems and threatens human health. Thus, methods allowing efficient dyes removal from wastewater are substantially desirable. In this work, we fabricated graphene oxide-polydopamine (GO-PDA) by microfluidics, which enables rapid synthesis of products with excellent uniformity due to the precise control of reaction conditions. In addition, the GO-PDA/ thermoplastic polyurethane (GO-PDA/TPU) composite fibrous membrane was prepared in a high-efficiency manner by microfluidic electrospinning with a four-channel chip. Interestingly, GO-PDA not only improves the mechanical strength and hydrophilicity of the composite fibrous membrane, but also endows the membrane with efficient dye adsorption and separation capacity both for single and mixed dyes. It has been proved that the GO-PDA/TPU composite fibrous membrane exhibits selectivity towards cationic dyes, where the removal efficiency is up to 99 wt%. Moreover, the fibrous membrane could be utilized in a continuous and cyclic manner, which still maintains a high adsorption rate (>95 wt%) after 5 recycling, illustrating outstanding durability and reusability. This work proposes an efficient GO-PDA/TPU composite fibrous membrane towards selective adsorption of cationic dyes, which is of great significance in wastewater purification.

Study of Low Temperature-Treated Aldolized Cellulose Nanocrystals for Enhancing Dye Separation and Self-Healing Properties of Graphene Oxide Membranes.

Graphene oxide (GO) membranes with a 2D layered structure and nanoscale channels have great application prospects for dye wastewater purification. In this paper, ethylenediamine (EDA) was grafted onto the surface of GO nanosheets at 70 °C and aldolized cellulose nanocrystals (ICNC) were introduced to form EDA-ICNC hydrogel structures between the GO nanosheets by Schiff base reaction. The interlayer structure of the membrane was determined by adjusting the amount of ICNC added and the degree of aldolization, and the EGOICNC-24 membrane with the best performance was prepared. The water flux is not only 12 times higher than that of GO membrane but also has a good separation ability for dye molecules with a molecular weight around 300. Following the EDA-ICNC-24 hydrogel cross-linking process, the tensile strength of the EGOICNC-24 membrane exhibited a 173% increase relative to that of the GO membrane. Additionally, the dye rejection rate reached 97.16% after 130 h of dye separation. When the surface of the membrane was damaged, it was self-healed by regulating the repair temperature and adding a very small amount of ICNC to undergo a dynamic Schiff base reaction and a synergistic effect of hydrogen bonding.

Ultrahydrophilic Inorganic Nanosheet-Based Nanofiltration Membranes for High Efficiency Separations of Inorganic Salts and Organic Dyes.

Two-dimensional (2D) inorganic nanomaterials have garnered extensive attention in the fabrication of inorganic nanofiltration membranes due to their unique structures and properties. In this study, we developed a facile process for fabricating large-scale ultrahydrophilic nanofiltration membranes using layered titanate H1.07Ti1.73O4·nH2O nanosheets (HT-ns). A drying deposition process was used to fabricate HT-ns membranes on a poly(tetrafluoroethylene) (TF) substrate. To enhance the bonding strength between the substrate and the deposited HT-ns membrane, the substrate surface was modified with a Cu2+-adsorbed silane monomolecular layer, connecting a negatively charged HT-ns membrane and a positively charged substrate surface. The fabricated HT-ns membrane exhibited an excellent rejection performance for inorganic salts and dye molecules. The ultrahydrophilicity of HT-ns membrane with a low water contact angle of 31° results in an ultrafast water permeance, which is approximately 6 times higher than that of a simple graphene-based nanofiltration membrane. The results open a new avenue to a new category of ultrahydrophilic nanofiltration membranes.

Multifunctional electrospun membranes incorporated with metal oxide nanoparticles, cellulose acetate, and polyvinylpyrrolidone for wastewater treatment: Oil/water separation, dye adsorption, and dye degradation

Multifunctional membranes have gained considerable attention as useful materials for the treatment of complex wastewater that contains dye and oil substances. Electrospun nanofiber membranes (ENM) have substantial advantages and potential for complex wastewater remediation, owing to their unique properties. In this study, an environmentally compatible ENM is fabricated by incorporating photocatalytic metal oxide nanoparticles of zinc oxide (ZnO) or silver-zinc Oxide (Ag-ZnO) into cellulose acetate (CA)/polyvinylpyrrolidone (PVP) nanofibers using electrospinning. Composite membranes ZnO/CA/PVP, Ag-ZnO/CA/PVP, ZnO/DCA/PVP (DCA: deacetylated cellulose acetate), and Ag-ZnO/DCA/PVP (deacetylated) were employed for oil–water emulsion separation, owing to their superhydrophilic and underwater superoleophobic nature, photocatalytic dye degradation due to the presence of ZnO or Ag-ZnO, and dye adsorption resulting from their high surface area. The composite membranes showed more than 95% efficiency for oil/water separation, malachite green adsorption, and photocatalytic methylene blue degradation. These membranes displayed simultaneous oil–water and dye separation efficiency, as well as antibacterial properties. The membrane we present here provides a simple and effective platform for wastewater remediation with a low energy consumption.

BiOCl-PVDF nanofibrous membrane for synergic oil-water separation and degradation of dye

Polymeric membranes have garnered remarkable attention, attributed to the significant breakthrough in the filtration of oily wastewater. However, the major setbacks of pristine polymeric membranes include susceptibility to fouling and chemical instability. Addressing such issues, this work focusses in the modification of polymer membranes using a metal oxyhalide, such as Bismuth oxychloride (BiOCl). This modification not only enhances water purification capabilities but also strengthens the membrane, protecting it from environmental deterioration and extending its lifespan. BiOCl was integrated into an electrospun pristine nanofibrous polymeric membrane using hydrothermal technique. The synthesized membrane matrix displayed superhydrophilicity and underwater superoleophobicity, effectively separating oil-in-water mixtures and emulsions. Moreover, BiOCl was effectively utilized to assess organic pollutant adsorption and degradation through photocatalysis. In addition, the membrane exhibited exceptional recyclability and withstood harsh conditions, contributing to its mechanical stability. The numerous advantages, enhance the effectiveness of BiOCl modified membrane in water pollution remediation.

Functionalized expanded graphite foam supported by PVDF skeleton for cationic dyes selectively separating and purifying

In order to fully utilize the advantages of expandable graphite (large specific surface area and porous structure), a solvent-free method was used to provide a supporting skeleton for expandable graphite through melting, bonding and solidification of polyvinylidene fluoride (PVDF). Based on its porous structure and enhanced mechanical stability, the formed PVDF/expandable graphite composite foam, amounts of functional groups were introduced throughout the foam (outside on the surface and inner side in the expandable graphite) by deposition of tannic acid (TA) and dopamine (DA), endowing it selective adsorption characteristics. The functioned foam exhibited excellent dynamic dye adsorption capacity by capturing dye molecules firmly through π-π interaction, hydrogen bonding, and charge attraction between the functional groups and dyes. Furthermore, with low zeta potential (-24.9 mV), the functional groups showed selective adsorption properties resulting in rapid separation of cationic dyes and anionic dyes. The functionalized PVDF/expandable graphite composite foam contact these two materials together in order to complement each other's advantages, showing a new research orientation for the treatment of different types of dyestuff wastewater.

Cholesterol Based Organogelators in Environmental Remediation: Applications in Removal of Toxic Textile Dyes and Oil Spill Recovery.

Oil spills in the ocean and textile dyes have a catastrophic impact on the environment, economy, and ecosystem. Phase-selective organic gelator dye sorption and oil separation for oil adsorption should meet certain criteria such as facile synthesis, low cost, effective gelation, and recyclability. This study has discovered that an aliphatic chain synthetic amphiphile based on cholesterol can produce organogels in a variety of organic solvents. Numerous methods, such as X-ray diffraction, Fourier-transform infrared spectroscopy, high-resolution scanning electron microscopy, and rheology, have been used extensively to examine and describe these organogels. An environmentally acceptable technique for achieving hazardous dye separation is presented here. For the sustainable filtration of dye-contaminated water, a new, straightforward, one-step method driven by gravitational force has been employed by using a gel column. This approach has shown excellent stability and reusability with repeated use, and it is easily scalable for the effective removal of a wide range of hazardous dyes. Furthermore, because the oil fraction was absorbed in the gel, the study showed how well it might be used to apply phase selectivity to separate the oil-water mixture from marine accidents. Furthermore, a straightforward distillation method can be used to quantitatively recover the oils contained in the gel and gelator molecules in phase-selective gelation. This low-tech, ecofriendly, and highly effective method also offers valuable insights into the development of advanced materials for separating toxic dyes and oil from water.

Synthesis and characterization of magnetic carbon dots (CDs)-based hybrid material as an adsorbent for the removal of organic dye from water

In recent years, the rapid advancement of materials science and the desire for new functions has led to an enormous demand for novel materials, which could be used in various applications. As a result, hybrid materials have gained the interest of the scientific community due to the infinite combinations of individual components, which could lead to materials with unique properties. In this study, a carbon dots (CDs)-CuFe2O4 nanohybrid material was successfully prepared through a solvothermal process and utilized as an adsorbent for the removal of Congo Red (CR) dye from aqueous environment. The nanohybrid material combines interactive surface functional groups due to CDs and high magnetic saturation due to CuFe2O4 nanoparticles, resulting in enhanced selectivity towards CR dye and easy separation after utilization with an external magnet. The as-prepared material was characterized by various techniques, including XRD, micro-Raman, FT-IR, HR-TEM/EDS, N2 porosimetry, and SQUID. Finally, its capability in the removal efficiency of CR dye was investigated at different initial CR concentrations, contact times and pH values via UV–Vis spectroscopy.

Efficient removal and separation of cationic dyes by microbubbles for electroflotation coupling membrane electrosorption

In order to enhance the treatment efficiency of cationic dyes wastewater, a dual chamber reactor was ingeniously designed to combine electroflotation and electrosorption technologies. The electrochemical system effectively removed representative single and mixed cationic dyes within 64 min at 150 mA. The observable reaction process phenomena, microbubble photos, clear Tyndall effect phenomena, and electrochemical experimental results all indicated the crucial role of electroflotation in removing cations dyes. Furthermore, changes in surface color, morphology, and functional groups of the anion exchange membrane before and after electrolysis suggested that the electrosorption process also contributed significantly to the removal process. Analysis using UV–vis absorption spectrum and high-resolution mass spectroscopy indicated that no significant chemical reaction occurred with the cationic dye during this process; thus, confirming that the separation of the cationic dye was a physical removal process. This study provides valuable theoretical guidance for efficient removal and separation of cationic dyes in wastewaters.

Construction of multiple interpenetrati ng network electric field-assisted healing hydrogel composite damage-resistant membrane

Inspired by the intrinsic self-healing ability of organisms, this study proposes to incorporate healing properties into separation membranes that are susceptible to physical damage during installation, operation, maintenance, and cleaning. The polyacrylic acid (PAA) hydrogel-modified layer was first obtained by in situ cross-linking and free radical polymerization in this research. After that, the construction of multiple interpenetrating three-dimensional (3D) network hydrogel-modified layers was realized via inserting amininated carbon nanotubes (CNTs-NH2) and Fe3+. Under the external effect of the electric field, the reversible dynamic linkage bonded in the conductive network constructed by CNTs-NH2 and Fe3+ benefited the rearrangement and diffusion of PAA molecular chains at the fractured interface. The dye separation performance of the composite membrane was restored to ca. 90 % of the initial level without affecting the dynamic operation after damage. The hydrogel-modified layer can be structurally stabilized for as long as 100 days. The Fe3+/CNTs-NH2/PAA/PES hydrogel composite membrane maintained a pure water flux of as high as 124.66 L m−2 h−1∙bar−1. This coating also exhibited excellent electrical conductivity (714.33 Ω/sq), mechanical strength (4.31 Mpa), repair, and screening capabilities. It provides a theoretical basis for achieving industrial scale-up and demonstrates good application prospects and empowerment potential.

Alginate functionalized sugarcane cellulose-based beads to improve methylene blue adsorption from aqueous solution

The study was carried out with the goal of synthesizing composite bead of cellulose, chitosan functionalized by sodium alginate using as an efficient and applicable adsorbent for methylene blue removal. Fabricating parameters of the material synthesis process like cellulose mass, sodium hydroxide concentration, immersing time and sodium alginate concentration were assessed in detail. The dye adsorption performance in water under the influence of pH, contact time, dye initial concentration, the material mass, shaking speed, temperature was also thoroughly evaluated. The results of advanced analyses showed that the beads were successfully synthesized with a rough surface and mesoporous structure. The adsorption isotherm and adsorption kinetics of dye adsorption process exhibited that the process was consistent with the Freundlich adsorption isotherm and the pseudo-second-order kinetic model, indicating a favorable physical adsorption process with multilayer of the dye on the adsorbent surface. The intra-particle diffusion model showed the strong dye adsorption by the beads occurred during the first two and half hours. The adsorbent could maintain its adsorption performance of 86 % for three times of regeneration. Finally, this study provided a recyclable and effective adsorbent for dyes separation from water.

Oxidation two-dimensional porous carbon membrane for efficient and precise separation of mixed dyes solution

In actual production, dye wastewater typically contains a mixture of two or more dyes. Therefore, developing efficient and precise separation techniques for mixed dyes solution is of great value but still faces great challenges. In this study, we prepared two-dimensional porous carbon sheets (PCS) using Ti3C2 as the precursor through halogenation etching technology. Subsequently, the PCS was oxidized with nitric acid at room temperature to obtain oxidized porous carbon sheets (OPCS). When mixed dyes solution RB/MO and RB/MB were screened using OPCS vacuum filtration self-assembled porous carbon membrane (OPCSM), the rejection rate for the larger dye RB was 99.9 %, while the permeation rates for the smaller dyes MO and MB were 91.0 % and 99.5 %, respectively. Notably, OPCSM also exhibited much higher water flux than the previously reported. The combination of high water flux and precise screening make OPCSM a highly promising membrane for the separation and reuse of mixed dyes.

PH independent adsorption: Reusable zinc-ferrite nanospheres for the selective recovery of dyes from binary mixtures

Efficient separation of colorant pollutants is a formidable challenge, prompting research into innovative materials. We developed zinc-ferrite nanoparticles via the Microwave-Assisted Solvothermal Technique (MAST), exploiting judicious solvent compositions to enhance Lewis's acidity. Upscaling to gram batches yielded nanoparticles with a higher specific surface area (149 m2g−1). These nanoparticles demonstrated selective separation of dyes from binary mixtures, including Orange-G (OG), Fluorescein-Sodium (FSS), and Methyl-Orange (MO), with their high sorption rate fitting to the pseudo-second-order kinetic model. Langmuir isotherm for OG and MO were observed with respective adsorption capacity (qm) of 94.12 mg/g, 104.28 mg/g, whereas FSS more likely matched Sips isotherm with qm = 124.31 mg/g at natural pH in room temperature (27 °C). Desorption, reliant on solution pH and OH− ions, enabled efficient regeneration and multiple reuses without significant efficiency loss over five reuse cycles. Remarkably, selective separation was independent of surface charge and remained effective across a wide pH range and in the presence of common anions, namely I−, NO3−, C2H3O2− routinely encountered in dye effluents. This ecologically safe, scalable adsorbent offers a promising solution for expensive dye recovery.

Lanthanum hydroxide@cellulose membranes with tunable pore sizes for selective removal of dyes with the same charges

Adsorptive membranes for the efficient separation of dyes with the same charges are quite desirable. Herein, a novel membrane of lanthanum hydroxide/cellulose hydrogel coated filter paper (LC) was prepared through a facile strategy of dip-coating followed by freeze-shaping. With the aid of cellulose gel, the generated La(OH)3 achieved fine dispersion. In addition, the pore size of LC membrane could be regulated by altering the cellulose concentration or the lanthanum chloride dosage, which was crucial for its water flux. In particular, the obtained membrane possessed a high water flux (128.4 L m−2 h−1) and a high dye rejection (97.2 %) for anionic Congo red (CR) only driven by the gravity, which outperformed many previously reported membranes. More intriguingly, its dye rejection for anionic methyl orange (MO) was only 0.9 %, exhibiting high selectivity for dyes with the same charges. Single-solute adsorption experiments indicated that the CR adsorption on the membrane was best fitted by the pseudo-first-order kinetic model, and it followed the Langmuir monolayer adsorption mechanism.