Selective Removal Of Cationic Dyes Research Articles

Lignin-derived sulfonated porous carbon from cornstalk for efficient and selective removal of cationic dyes

The presence of dye effluents released from dye-using industries has emerged as a great environmental concern in recent years. Adsorption is considered as an efficient method for capturing contaminants from wastewater. However, due to limited adsorption efficiency, selectivity, and regeneration capability of adsorbents, it is difficult to solve the prevailing dye effluent issue. In this work, we prepared a highly efficient and selective lignin-derived sulfonated porous carbon (LSPC) adsorbent from cornstalk by a facile etching-sulfonation process by using Fe3O4 as a templating agent. Profiting from high density of negatively charged groups (including − SO3H, −COOH, and phenolic − OH), the prepared LSPC showed outstanding selectivity for rapid removal of cationic dyes due to electrostatic affinity. LSPC exhibited great pH responsiveness towards methylene blue adsorption capacity, which increased drastically from 234.19 mg/g to 621.52 mg/g when pH value increased from 2 to 11. Moreover, the LSPC demonstrated excellent regenerated property. On account of its excellent selectivity, strong adsorption capacity, facile regeneration, and great reusability, the lignin-derived sulfonated porous carbon holds great potential towards selective adsorption and recycle of cationic dyes in water treatment field.

In-situ synthesis of carbon dot at cellulose nanofiber for durable water treatment membrane with high selectivity

In this work, carbon dot (CD) was in-situ synthesized and attached to cellulose nanofiber (CNF) via hydrothermal process. The in-situ synthesized CD uniformly enveloped the CNF surface by means of amide bonding, without significant changes of the chemical structure of CNF. The prepared CD@CNF composite showed rough and bumpy morphology. The attached CD increased the interaction between the fibers and enhanced the thermal stability and the dimensional stability in aqueous solution. CD@CNF showed excellent performance as a dye-rejection membrane with high-water flux (∼32 LMH bar−1) and high rejection rate (∼99.8 %), as well as the selective removal of cationic dye. This study suggests a novel synthesizing method of durable CNF membrane by envelopment of CD for effective water treatment.

Green synthesis of iron nanoparticle by tea extract (polyphenols) and its selective removal of cationic dyes

The traditional synthesis of iron nanoparticles has the problems of high cost and secondary pollution. There is an urgent need for an economic, effective and environment-friendly method to solve this key issue. Here, the iron nanoparticles were prepared by a novel biosynthesis based on extracted tea polyphenols. Five kinds of tea were tested by microwave method, and the optimum extraction conditions were determined by orthogonal experiment L9 (34). The obtained materials were characterized by XRD, SEM, FTIR, XPS, Zeta potential and UV–Vis. The iron nanoparticle has a regular spherical or ellipsoidal shape with a particle size of about 75–100 nm. It was noted that it shows good selective removal for cationic dyes (malachite green (MG), rhodamine B (RB) and methylene blue (MB)). Kinetic experiment of iron nanoparticle on cationic dyes was in accordance with the pseudo first order kinetic model. Further, the possible removal mechanism was proposed, which mainly involves the process of adsorption and reduction. Mostly, its removal capacity of Malachite green reaches as high as 190.3 mg/g.

Micro-mesoporous divinyl benzene-based polymer for ultrafast, effective and selective removal of cationic dyes

Poly(divinyl benzene-co-maleic anhydride) (PDVB-MAH) with hierarchically micro-mesoporous structure was fabricated by a facile sol-gel method, which was used as an adsorbent for the removal of cationic dyes including methylene blue (MB), rhodamine B (RhB), methyl violet (MV) and malachite green (MG) from wastewater. The resulting PDVB-MAH possessed micro-mesoporous structure with the surface area of 209 m2 g−1, which could facilitate the mass transfer process. The effects of pH (2–10), adsorbent dosage (0.2–2.0 g L−1), contact time, salt concentrations (0.1–0.6 mol L−1), initial concentrations (50–600 mg L−1) of dyes and temperature (298, 308 and 318 K) on the adsorption performance were investigated. The selective adsorption for cationic dyes was rapid and quantitative where removal efficiencies of 100% were obtained for MB and RhB within 5 and 15 min, respectively. The adsorption capacities of PDVB-MAH were 315.9 mg g−1 and 420.4 mg g−1 for MB and RhB, respectively. The adsorption behaviors on MB and RhB were accordance with the pseudo-second-order model and Sips model. The estimated thermodynamic parameters indicated the adsorption process was spontaneous and exothermic. Furthermore, the synergistic effect of π–π stacking interaction and electrostatic attraction was confirmed with the help of FTIR spectroscopy and DFT method. These results demonstrated that the PDVB-MAH could be a potential polymeric adsorbent with efficient dye removal from colored wastewater.

Biosynthesized gold nanoparticles as photocatalysts for selective degradation of cationic dye and their antimicrobial activity

Herein, polyphenol stabilized gold nanoparticles (AuNPs) have been synthesized for selective removal of cationic dyes from aqueous solution. Gold nanoparticles have been synthesized using Cassytha filiformis plant extract and characterized by UV–vis spectroscopy (UV–vis), High-Resolution Transmission Electron Microscopy (HR-TEM) and X-ray diffraction (XRD). The size of AuNPs was found to be in the range of 8–20 nm with an average size of 12 nm. The newly generated AuNPs demonstrate excellent potential in removing cationic dye such as methylene blue (MB) via photocatalytic degradation under sunlight. The adsorption/degradation behaviour of cationic MB on AuNPs adsorbent from the aqueous solution was studied by varying parameters such as pH and different light sources. Alkaline pH and sunlight were found to be crucial in dye degradation. The adoption of the ultrasonic waves (UW) leads to reduce sorption time significantly with an increase in the sorption ability and at the optimum condition. The AuNPs appear to be promising with a maximum dye loading capacity of 595.23 mg/g and dye degradation efficiency was found to be 87 % after 20 min. Additionally, the antimicrobial studies confirm the significant inhibition (zone of inhibition: 20 mm) of growth of Mycobacterium smegmatis, a model organism for Mycobacterium tuberculosis, suggesting the advancement of a novel new generation eco-friendly and cost-effective ‘green’ AuNPs.

Fabrication porous adsorbents templated from modified sepiolite-stabilized aqueous foams for high-efficient removal of cationic dyes

High internal phase emulsions (HIPEs) as template for fabrication of porous materials has attracted much attention, due to the high porosity and tunable porous structure. But the enormous consumption of organic solvents is still a nightmare for the practical application. In comparison, the aqueous foam without need any organic solvent and hence has greater advantages in the porous materials preparation. In this study, a novel Pickering foam which was stabilized by modified sepiolite (Sep) was prepared and applied as the template for preparation of the porous material via thermal-initiated polymerization. The Pickering foam had excellent ability and stability in the pH of 4–11 and the obtained porous adsorbent possess sufficient and tuned pore structure. The porous materials as adsorbent has favorable performance for adsorption and selective removal of cationic dyes, and the understanding adsorption capacities for Methylene blue (MB) and Methyl green (MG) can be achieved with 1421.18 mg/g and 638.81 mg/g within 60 and 45 min at 25 °C, respectively. This porous material can be as the potential adsorbent for adsorption or separation of organic pollutants.

Efficient and highly selective adsorption of cationic dyes and removal of ciprofloxacin antibiotic by surface modified nickel sulfide nanomaterials: Kinetics, isotherm and adsorption mechanism

In the present work, the nickel sulfide nanomaterial with the negative surface charge was synthesized by a simple and eco-friendly route using nickel acetate, thioacetamide and l-glutathione reduced (GSH). The new surface-modified nanomaterial was systematically characterized using various techniques such as XRD, FE-SEM, TEM, EDX, XPS, TGA, Zeta-potential, and FT-IR, and then applied for the removal of dyes and antibiotics. The nanomaterial exhibited selective adsorption towards cationic dyes: methylene blue (MB) and crystal violet (CV) with a high adsorption capacity of 1006.52 mg g−1 and 1946.61 mg g−1, respectively. The adsorption capacity for the removal of ciprofloxacin antibiotic (CIP) was 971.83 mg g−1 which is extremely high. The selectivity of MB in binary mixtures was investigated using two anionic dyes: methyl orange (MO) and orange G (OG). The separation efficiency (α) for MB in MB/MO and MB/OG mixtures was 97.75 % and 99.16 %, respectively. The adsorption process for all the adsorbates followed pseudo-second-order kinetics and the Freundlich isotherm model. The mechanism of interaction was analyzed through pH effect, zeta-potential measurement, FT-IR and XPS analysis, implying that the electrostatic interaction is mainly involved in the adsorption. In addition, the parameters like the effect of initial dye concentration and temperature on the adsorption process were studied. The adsorbent is reusable up to 4 times with 97 % efficiency. Thus, the prepared GSH-capped nanomaterial is an effective adsorbent for the removal of antibiotics and the selective removal of cationic dyes with high adsorption capacity.

Highly selective removal of cationic dyes from water by acid-base regulated anionic functionalized polyacrylonitrile fiber: Fast adsorption, low detection limit, reusability

A series of anionic functionalized polyacrylonitrile fibers were prepared and used to remove cationic dyes from water. The phenolate immobilized fiber (PANP(−)F) exhibited excellent adsorption capacities for cationic dyes, among which the best results was obtained for Brilliant cresyl blue (BCB) with color changing of the solution from sapphire to light yellow. Additionally, PANP(−)F can selectively remove cationic dyes from dye mixtures containing both anionic and cationic dyes. After acid-base regulating, the highest adsorption capacity of PANP(−)F was obtained at pH 10. Moreover, adsorption kinetic illustrated that PANP(−)F can achieve half adsorption capacity within 10 mins and follow pseudo-second-order model. The maximum adsorption capacity calculated from isotherms experiments reached 2.306 mmol/g (890.1 mg/g) at 25 °C. The activation energy of the adsorption process was 30.74 kJ/mol indicating that the BCB adsorption process occurs via chemical adsorption. Furthermore, the PANP(−)F can be readily separated from solution and reused 10 cycles. Under a continuous flow condition, the BCB concentration can be reduced to 20 ppb at first and remained below 1.69 ppm during the 825 mins adsorption process. At the same time, the removal ratio kept above 98.31%. In general, this novel PANP(−)F adsorbent is eco-friendly, highly efficient, selective, reusable, and has great potential for the removal of dyes from industrial wastewaters.

Structural control of cellulose nanofibrous composite membrane with metal organic framework (ZIF-8) for highly selective removal of cationic dye

Highly durable cellulose nanofibrous composite membranes were prepared by in-situ growing of zeolitic imidazolate frameworks (ZIF-8) as spacers in the presence of TEMPO oxidized cellulose nanofibers (TOCN) as their anchoring points. The obtained composite membranes showed three-dimensionally networked nanofibers with ZIF-8 to generate porous structures, which gave high durability without critical compaction of the membrane under pressure (1∼3 bar). The 20 μm thick ZIF-8/TOCN membrane showed most superior water flux (84 Lm−2 h-1 bar-1) without critical flux drop for 24 h operation. Interestingly, the composite membrane exhibited highly selective removal of cationic dyes in the presence of anionic dyes due to strong interaction through negatively charged TOCN networks. The experimental results in the study reveal a novel strategy for durable cellulose nanofibrous membrane via introduction of metal organic frameworks for highly selective filtration.

Ultrathin sodium ferric silicate 2D nanosheets: A novel and robust adsorbent for selective removal of cationic dyes in wastewater

Sodium ferric silicate nanosheets with ultrathin 2D structure were firstly synthesized by hydrothermal method using ferric nitrate and sodium silicate as precursors. The as-prepared nanosheets were characterized by SEM, TEM, AFM, XRD, XPS and N2-physisorption. Adsorption of ten dyes (including 5 cationic dyes and 5 anionic dyes) from aqueous solutions was investigated and discussed. The nanosheets were found to be amorphous and had a thickness of 0.85 nm. The ultrathin nanosheets displayed remarkable selective adsorption capacity toward cationic dyes due to the features of high specific surface area, negative charged surface and good mass transportation property. In particular, such ultrathin nanosheets showed a maximum adsorption capacity of 1.77 mg m−2 per unit surface area for methylene blue (MB), which is the highest value among the reported silicates adsorbents. The equilibrium adsorption data of MB suggested that the Langmuir model was much more suitable for the experimental data, and the pseudo-second-order kinetic equation could well describe the adsorption kinetics. Moreover, the sodium ferric silicate nanosheets could be regenerated by simple calcination and used repeatedly in dyes removal, demonstrating the potential application in wastewater purification and treatment.

Effective and selective removal of cationic dye from aqueous solution using rosin derivative modified wheat straw

Effective and selective removal of cationic dye from aqueous solution using rosin derivative modified wheat straw

Selective removal of cationic dyes using response surface methodology optimized gum acacia-sodium alginate blended superadsorbent

Gum acacia and sodium alginate were blended to synthesize highly efficient superadsorbent formed by grafting of poly(acrylic acid) (AA) used as monomer onto the hybrid of gum acacia and sodium alginate and the polymeric chains were crosslinked through N,N′-methylene bisacrylamide (MBA). The overall reaction followed free radical polymerization with ammonium persulphate (APS) used as initiator. Response surface methodology integrated with central composite design (RSM-CCD) could synthesize semi-Interpenetrating network (semi-IPN) having maximum swelling capacity of 1749.2% at MBA, APS and AA concentrations of 0.89 × 10−2 mol L−1, 3.29 × 10−2 mol L−1 and 1.46 mol L−1, respectively using 15 mL water at 70 °C for 2.5 h. The synthesized sample was found to be selective for removal of cationic dyes upto 97.49%, 95.39% and 94.56% for auramine-O (AO), malachite green (MG) and crystal violet (CV), respectively. Adsorption capacities at equilibrium were calculated experimentally as 2.01 mg g−1, 3.06 mg g−1 and 7.55 mg g−1 for AO, MG and CV, respectively. These dyes could be desorbed with 0.1 N HCl for the recyclization of semi-IPN. Adsorption mechanism involved monolayer formation with three step process of adsorption and followed first order kinetics. Exothermic nature of adsorption was revealed by thermodynamic studies.

Rapid synthesis of a silsesquioxane-based disulfide-linked polymer for selective removal of cationic dyes from aqueous solutions

Developing a facile and rapid method to prepare adsorbents for an efficient and selective removal of dyes is of great importance for human health and environment. In this work, a silsesquioxane-based disulfide-linked polymer (DLP) was rapidly synthesized by a simple oxidative coupling reaction of octa(3-mercaptopropyl)silsesquioxane within 2 min at room temperature. The synthesized DLP demonstrated selective and efficient adsorption of cationic dyes over anionic dyes with the maximum capacities of 12.94 mg g−1 for methylene blue, 18.47 mg g−1 for rhodamine B and 26.69 mg g−1 for crystal violet. The high uptake and selectivity for cationic dyes was attributed to the electrostatic interactions between the anionic charges from sulfur and oxygen anions formed by the deprotonation of thiols and hydroxyls in the DLP and the cationic charges from the dyes, and the swelling behavior of the DLP. To investigate the adsorption process, the effect of various factors such as contact time, initial concentration, temperature, and pH on the adsorption activity of cationic dyes was studied. The adsorption equilibrium data showed a better fitting to the Langmuir isotherm model than the Freundlich model and the adsorption kinetics fitted well with the pseudo-second-order kinetic model, indicating that the adsorption process is mostly governed by the chemisorption behavior. Additionally, the absorbent was recyclable with the adsorption capacity being >95% after five times recycle adsorption. These results indicated that the present disulfide-linked polymer could be promisingly applied as an efficient adsorbent for the selective removal of cationic dyes from industrial wastewater.

Facile Fabrication of Magnetic Metal-Organic Framework Composites for the Highly Selective Removal of Cationic Dyes.

In this work, we show a novel magnetic composite material Fe3O4@HPU-9 (HPU-9 = {[Cd(L)0.5(H2O)](DMA)(CH3CN)}n) (H4L = 1,1′-di(3,5-dicarbonylbenzyl)-2,2′bimidazoline, DMA = N,N-dimethylacetamide) constructed by in situ growth of HPU-9 on Fe3O4, which has excellent absorption of cationic dyes from aqueous solution. The Fe3O4@HPU-9 particle possesses a well-defined core-shell structure consisting of a Fe3O4 core (diameter: 190 nm) and a HPU-9 shell (thickness: 10 nm). In the composite, the HPU-9 shell contributes to the capsulation of cationic dyes through electrostatic attractions between HPU-9 and cationic dyes, while the Fe3O4 core serves as magnetic particle. The maximum absorption capacity of Fe3O4@HPU-9 for R6G was 362.318 mg·g−1. The absorption kinetics data were well described by a psedo-second-order model (R2 > 0.99), and the equilibrium data were also well fitted to Langmuir isotherm model (R2 > 0.99). Our data confirmed that the proposed magnetic composite could be recycled and reused several times without centrifugal separation, making it more convenient, economic and efficient than common adsorbents.

An anionic metal-organic framework as a platform for charge-and size-dependent selective removal of cationic dyes

A novel anionic framework {[Me2NH2]0.5[In0.5L0.5]·xDMF}n (1) with two one-dimensional (1D) channels along the b axis of about 7.37 × 11.95 Å and 6.58 × 7.24 Å was solvothermally synthesized and characterized. The adsorption studies on organic dyes having different charges and sizes indicate that compound 1 exhibits selective adsorption and separation behavior for cationic dyes through an ion-exchange process due to the presence of an intrinsic anionic framework. Additionally, compound 1 can selectively separate methylene blue (MB+) from the cationic dyes mixture consisting of methylene blue (MB+) and rhodamine B (RhB+). Moreover, when implemented as chromatographic column stationary phases, compound 1 displays efficient and selective separation of MB+ from both anionic-cationic dyes mixture and only cationic dyes mixture.

One-step electrospinning of negatively-charged polyethersulfone nanofibrous membranes for selective removal of cationic dyes

Abstract The conventional strategies employed for introducing functional groups onto the surfaces of nanofibrous membranes (NFMs) require complicated steps. Herein, we report a simple strategy for the fabrication of negatively-charged polyethersulfone (PES) NFMs adsorbent by utilizing one-step electrospinning. Firstly, functional groups were introduced into the electrospinning solution via in-situ cross-linking co-polymerization of sodium styrene sulfonate and acrylic acid in PES solution. Then, the solution was directly used to electrospin into negatively-charged PES NFMs. Sufficient characterization methods were carried out to demonstrate the successful fabrication of the functional NFMs. Batch adsorption experiments for various kinds of dyes with different initial concentrations and pH values were carried out. The results indicated that the NFMs showed efficient adsorption capacity for cationic dye of methylene blue MB. In particular, binary dye adsorption column experiments were carried out and the membranes exhibited excellent separation efficiency of 98.29% for MB/amaranth mixture. The successful fabrication of such fascinating NFMs adsorbent by using this simple approach may provide new sights into the design and development of adsorptive materials for industrial wastewater treatment with excellent separation efficiency towards mixed dyes.

Synthesis and characterization of a series of novel perovskite-type LaMnO3/Keggin-type polyoxometalate hybrid nanomaterials for fast and selective removal of cationic dyes from aqueous solutions.

In this paper, Keggin-type heteropoly acids H3PMo12O40 (PMo12), H3PW12O40 (PW12) and H4SiW12O40 (SiW12) were successfully supported on silica-coated perovskite type LaMnO3 nanoparticles by a simple acid-base reaction. These novel hybrid nanomaterials (denoted as LaMnO3@SiO2/PMo12 (1), LaMnO3@SiO2/PW12 (2), and LaMnO3@SiO2/SiW12 (3)) were characterized by means of FT-IR, PXRD, inductively coupled plasma (ICP) spectrometry, SEM, EDX, TEM and BET surface area analysis. Furthermore, the adsorption abilities of 1-3 were tested towards cationic methylene blue (MB) and anionic methyl orange (MO) dyes. The results revealed that the MB dye can be removed almost completely (≥98%) by adsorbents 1-3 in 1, 30 and 0.5 minutes, respectively. For the most efficient adsorbent 3, the effects of the initial concentration and the initial pH values of MB solution on its adsorption ability were examined. Furthermore, the selective adsorption of the hybrid materials towards mixed MB & MO solution was investigated. The nanomaterials 1-3 could be easily separated from the aqueous solution and reused several times without any impact on their adsorption abilities and structures.

Selective removal of cationic dye from aqueous solution by low-cost adsorbent using phytic acid modified wheat straw

In this paper, the wheat straw (WS) was modified using phytic acid (PA) to improve adsorption capacity for selective removal of methylene blue dye (MB, cationic dye). The morphology, structure and surface state of the modofied wheat straw using phytic acid (PA-WS) were characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The effects of pH, MB concentration, different temperatures and contact time on adsorption experiments were investigated. The maximum adsorption quantity of PA-WS for MB was up to 205.4mgg−1 at 25°C. Equilibrium adsorption isotherm data indicated a good fit to the Langmuir isotherm model and the adsorption kinetic was well-fitted by the pseudo-second-order model and the Elovich model. Regeneration study revealed that PA-WS can be reused effectively. These results indicated that PA-WS was a promising adsorbent for the removal of cationic dyes.

Preparation and characterization of sulfonated poly(styrene-alt-maleic anhydride) and its selective removal of cationic dyes

Abstract Sulfonated poly(styrene-alt-maleic anhydride) (SSMA) microspheres were prepared from poly(styrene-alt-maleic anhydride) (SMA) by sulfonation reaction and its adsorption behavior as an efficient adsorbent for the removal of organic dyes was systematically studied. The structure and morphology of SMA and SSMA were characterized by 13 C NMR, FTIR, EDS, XPS, SEM and TEM. The adsorption performance of SMA and SSMA toward organic dyes was investigated by batch mode adsorption experiments. Results indicated that the SSMA had much more adsorbability for cationic dyes such as methylene blue (MB) and Rhodamine B (RhB) compared to SMA. The adsorption capacity for MB of SSMA 8h which had been sulfonated 8 h was found to be 671.14 mg/g, while the adsorption capacity of SMA for MB was 344.83 mg/g at 25 °C, showing that the adsorption capacity for cationic dyes was enhanced 94.63% via the sulfonation. The kinetic studies revealed that the sorption followed a pseudo-second-order kinetic model which indicated that the adsorption interaction between adsorbent and adsorbate molecules was chemisorption. Moreover, adsorption isotherm mechanisms were analyzed by Freundlich and Langmuir models.

Nanocomposite hydrogels for selective removal of cationic dyes from aqueous solutions

Removal of organic dyes from waste water has received a significant attention in recent years. In this work, a set of nanocomposite hydrogels (NHs) were prepared and their capacity to absorb crystal violet (CV), a cationic dye, and acid yellow‐23 (AY), an anionic dye, from aqueous solutions was determined. NHs were prepared by in situ formation of Fe3O4 magnetic nanoparticles (MNPs) inside poly(acrylamide‐co‐4‐styrene sulfonic acid sodium salt) (P[AAm‐co‐SSA]) hydrogel matrices. The dye absorption capacity of the magnetic NHs (MNHs) was compared with simple hydrogels (hydrogels or SHs) without the MNPs The prepared hydrogels were characterized by FTIR, XRD, thermogravimetric analysis, high resolution TEM, field emission SEM, and vibrating sample magnetometer measurement. From HRTEM, it was confirmed that the prepared MNPs in hydrogel matrices were in the size range of about 8 to 10 nm. The MNHs showed greater swelling behavior as well as greater removal efficiency of cationic dye from aqueous solutions in comparison to the SHs. With increase of SSA mole percentage, dye removal efficiency was also increased for both types of hydrogels. The present study indicates that the hydrogels containing MNPs can be potentially used as an efficient absorbent material for removal of cationic dyes from waste water. POLYM. ENG. SCI., 56:776–785, 2016. © 2016 Society of Plastics Engineers