Adsorption Of Cationic Dyes Research Articles

Experimental and DFT insights into the adsorption competition of two cationic dyes on activated carbon derived from walnut shells in aqueous solutions

The adsorption of cationic dyes is more significant in the binary system compared to the simple system, making it a crucial element in the study of complex matrices. Experimental and theoretical investigations were conducted on the adsorption of two cationic dyes, Malachite Green (MG) and Safranin (SAF), on activated carbon derived from walnut shells (AC-Ws) in both simple and binary systems. The impact of pH and the volume of adsorbent in the two systems were exclusively examined. The electrophilic potency of the dyes influenced elimination efficiency. According to the theoretical analysis, MG proves to be more electrophilic than SAF, and therefore displays greater interaction with surface sites in both simple and binary systems, resulting in removal rates of 93.12% and 78.41%, correspondingly. Best removal results were achieved at pH 7 for both systems. The Langmuir model is the most fitting method to explain the removal of dyes, both in simple and binary systems. According to the results of the kinetic study, the phenomenon obeys the pseudo-second order. The theoretical and experimental studies are in alignment, and it can be deduced that the decrease in the elimination efficiency of SAF in the binary system is due to the decreased acceptance of electrons when SAF is present.

Selective Adsorption of Cationic and Anionic Dyes using Ni/Al Layered DoubleHydroxide Modified withEucheuma cottonii

This study investigates the selective adsorption capabilities of Ni/Al Layered Double Hydroxide (LDH) modified withEucheumacottoniifor the removal of cationic and anionic dyes from aqueous solutions. The primary objective was to evaluate the efficiencyand selectivity of these modified adsorbents towards different dyes, including rhodamine-b, malachite green, methylene blue(cationic dyes), and direct yellow, methyl orange, direct green (anionic dyes). The modification process aimed to enhancethe adsorption properties of LDHs, leveraging the natural adsorption capabilities ofEucheuma cottonii. Experimental resultsdemonstrated significant differences in adsorption percentages among the tested dyes, with malachite green showing thehighest adsorption efficiency among cationic dyes, indicating a strong affinity of the modified adsorbents towards cationic dyes.However, the ability to also adsorb anionic dyes suggests the dual-functionality of the modified LDHs, making them versatileagents for dye removal in water treatment applications.

Effect of conductive polyaniline on the cationic and anionic dye adsorption properties of amphoteric alginate/chitosan composite foams

Doped polyaniline is a widely used conductive material and could be used for adsorption based on the electrostatic neutralization effect through the protonation of the imine group. However, the adsorption effect and mechanism towards cationic and anionic pollutants are not clear. Herein, the conductive sulfonic acid doped polyaniline was introduced into alginate/chitosan amphoteric composite foams prepared with a thermal induced phase separation technique. The composite foams were characterized in terms of scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and electrochemical impedance. The composite foam exhibited rich pores and fibrous matrix due to the unique ternary solvent system. The polyaniline was well-distributed and enhanced the cationic dye adsorption ability, contrary to that of anionic dye. Compared with pure alginate/chitosan composite foam, the adsorption capacity of methylene blue was increased by 91.1%, and that of acid blue-113 was reduced by 49.2%. The adsorption rate of the two dyes was both increased. Polyaniline addition enhances the ionic mobility rate and accelerates the movement of dye molecules. Moreover, the composite foams exhibited excellent selective adsorption capacity and reusability. The study indicates that the conductive polymer could find its share in developing high-performance adsorbents.

Topotactic Conversion of Titanium-Oxo Clusters to a Stable TOC-Based Metal-Organic Framework with the Selective Adsorption of Cationic Dyes.

Titanium-oxo cluster (TOC)-based metal-organic frameworks (MOFs) have received considerable attention in recent years due to their ability to expand the application of TOCs to fields that require highly stable frameworks. Herein, a new cyclic TOC formulated as [Ti6O6(OiPr)8(TTFTC)(phen)2]2 (1, where TTFTC = tetrathiafulvalene tetracarboxylate and phen = phenanthroline) was crystallographically characterized. TOC 1 takes a rectangular ring structure with two phen-modified Ti6 clusters as the width and two TTFTC ligands as the length. An intracluster ligand-to-ligand (TTF-to-phen) charge transfer in 1 was found for TOCs for the first time. Compound 1 undergoes topotactic conversion to generate stable TOC-MOF P1, in which the rectangular framework in 1 formed by a TOC core and ligands is retained, as verified by comprehensive characterization. P1 shows an efficient and rapid selective adsorption capacity for cationic dyes. The experimental adsorption capacity (qex) of P1 reaches a value of up to 789.2 mg/g at 298 K for the crystal violet dye, which is the highest among those of various adsorbents. The calculated models are first used to reveal the structure-property relationship of the cyclic host to different guest dyes. The results further confirmed the host MOF structure of P1.

Exploring the thermal degradation of pine nut shells: a study on biochar production and its efficacy in cationic dye adsorption from water

Exploring the thermal degradation of pine nut shells: a study on biochar production and its efficacy in cationic dye adsorption from water

Cellulose Nanofibrils-Reinforced Pectin Membranes for the Adsorption of Cationic Dyes from a Model Solution.

In the presented research, a facile, one-step method for the fabrication of cellulose nanofibrils/pectin (CNFs/PC) membranes is described, which were tested further for their ability to remove cationic dyes from the prepared model solutions. For this purpose, ten membranes were prepared with different quantities of CNFs and PC with/without citric acid (CA) or CaCl2 as mediated crosslinking agents, and they were characterised comprehensively in terms of their physical, chemical, and hydrophilic properties. All the prepared CNFs/PC membranes were hydrophilic with a Water Contact Angle (WCA) from 51.23° (without crosslinker) up to 78.30° (CaCl2) and swelling of up to 485% (without crosslinker), up to 437% (CaCl2) and up to 270% (CA). The stability of membranes was decreased with the increase in PC; thus, only four membranes (M1, M2, M3 and M5) were stable enough in water after 24 h, and these were additionally applied in the adsorption trials, using two structurally different cationic dyes, i.e., C.I. Basic Yellow 28 (BY28) and C.I. Basic Blue 22 (BB22), in four concentrations. The highest total surface charge of M3 (2.83 mmol/g) as compared to the other membranes influenced the maximal removal efficiency of both dyes, up to 37% (BY28) and up to 71% (BB22), depending on the initial dye concentration. The final characteristics of the membranes and, consequently, the dye's absorption ability could be tuned easily by changing the ratio between the CNFs and PC, as well as the type and amount of crosslinker.

Green chemistry route to chitosan hydrogels and investigation of the materials as efficient dye adsorbents

Abstract Biopolymer-based materials for the adsorption of toxic dyes represent an interesting class of materials for environmental applications. Here we report on chitosan as the starting material for synthesizing dye adsorbents. In particular, the synthesis, characterization, and cationic dye adsorption properties of chitosan hydrogel adsorbents are reported. Polyanionic itaconated chitosan derivatives were synthesized in solvent-less conditions for the first time. Itaconated chitosan was cross-linked using thiol-ene chemistry to obtain hydrogels. The influence of the incorporated carboxylate groups and the cross-linker fraction on the adsorption of Methylene Blue (MB) was investigated. In addition, the impact of pH, adsorbent dose, initial concentration, and ionic strength were investigated to determine the optimum conditions for MB uptake, and the dye uptake kinetics, adsorption isotherms, selectivity, and reusability of the adsorbents were unveiled. A maximum adsorption capacity of 556 mg/g could be achieved, outperforming commercial activated charcoal and ion exchange resins. Furthermore the chitosan hydrogel adsorbents were shown to capture >90 % of cationic MB from a binary equimolar mixture with the anionic dye Methyl Orange. Since the adsorbents can be regenerated and re-used afterwards at least 20 times, retaining a high dye adsorption fraction of >95 %, these materials are promising candidates for environmental applications.

Microwave synthesis of amino-functionalized MCM-41 from coal gasification fine slag for efficient bidirectional adsorption of anionic and cationic dyes

Coal based solid waste has been recognized as a sustainable raw material for the preparation of high added value materials for wastewater treatment. In this paper, a preparation route was designed for the rapid, efficient, and low-cost preparation of MCM-41 zeolite using coal gasification fine slag as raw material. Functionalization modification of MCM-41 was carried out by grafting amino groups on its surface to improve its application performance. Moreover, the prepared functionalized material is used for bidirectional adsorption of anionic and cationic dyes. The experimental results indicate that MCM-41 zeolite with highly ordered pore structure was rapidly prepared using the advantages of fast heating and strong permeability of microwave synthesis method, with a specific surface area of up to 862.03 m2/g. Amine functionalized MCM-41 exhibits strong adsorption capacity for both cationic and anionic dyes, with maximum adsorption capacities for methylene blue and Congo red being 292.40 mg/g and 354.61 mg/g, respectively. The study of adsorption kinetics and adsorption mechanism indicate that the adsorption process is mainly controlled through chemical adsorption, including electrostatic attraction, hydrogen bonding, and π-π interactions. The results of this study will provide useful references for the use of coal based solid waste to prepare functional materials for the treatment of organic wastewater.

Sustainable aerogels based on biobased poly (itaconic acid) for adsorption of cationic dyes

This work reports the synthesis of poly (itaconic acid) by thermal polymerization mediated by 2,2′-Azobis(2-methylpropionamidine) dihydrochloride. Furthermore, physical hydrogels were prepared by using high molecular weight poly (itaconic acid) characterized by low dispersity and laponite RD. The hydrogels presented porous 3D network structures, with a high-water penetration of almost 2000 g/g of swelling ratio, which can allow the adsorption sites of both poly (itaconic acid) and laponite RD to be easily exposed and facilitate the adsorption of dyes. The water adsorption followed Schott's pseudo-second-order model. The mechanism of the adsorption process was investigated using 1H and 31P NMR. The hydrogel is able to fast adsorb by a combination of electrostatic interactions and hydrogen bonding by the synergic effect of the clay and poly (itaconic acid). Moreover, the prepared aerogels exhibited a fast removal of Basic Fuchsin, with an adsorption capacity of 67.56 mg/g and a high removal efficiency (~99 %). The adsorption followed the pseudo-second-order kinetic model and Langmuir isotherm model. Furthermore, the thermodynamic parameters showed that the BF process of adsorption was spontaneous and feasible, endothermic, and followed physisorption. These results indicated that the PIA/laponite-based aerogel can be considered a promising adsorbent material in textile wastewater treatment.

Adsorption of cationic dyes from aqueous solution onto modified nanocellulose reinforced porous bio based polyurethane hybrid composites

In this study polyurethane (PU) based porous composites were synthesized by using the biobased polyol derived from chaulmoogra and grape seed oils. These polyols were used for the preparation of porous PU composites using methylene diphenyl diisocyanate as hard segment and polyethylene glycol (PEG6000) as soft segment with 1,4-diazabicyclo[2, 2, 2]octane (DABCO) as catalyst. Swelling ratio of the PU were analyzed by using water, salt, acid and base buffers. Nanocellulose prepared from moringa olifera seed pods were modified (aminated, carboxylated and phosphorylated) and were added as fillers (1, 3, and 5 weight %) to obtain porous polyurethane composites. The prepared samples were also characterized by using XRD, SEM, FT-IR, along with other physical and chemical methods. The SEM results show the nanofibrillation of cellulose and closed cell porosity in polyurethane. The strength of nanocellulose filled polyurethane composites (mNC-PU) increased with the increase in the mNC-content. Using the obtained mNC as filler, porous polyurethane composite with good adsorption capacity were prepared, and were used for the adsorption of Indigo carmine (IC), Rhodamine-B(Rh-D) and mixed (binary) dye system. The experimental process parameters optimization was carried out using Box Behnken Design. The predicted and the experimental percentage of dye removal were found to be in good agreement with a maximum of experimental percentage dye removal being in the range of 85 to 94 % for both IC dye and Rh-D dye individually and from mixed dye system. The coefficient of determination value and adjusted coefficient of determination value indicated that the model had significant fit. An increase in pH was found to increase the sorption capacities of the porous polyurethane towards the dyes. Maximum adsorption was found in the higher pH range of 9–12.

In-situ surface enhanced Raman spectroscopy revealing the role of metal–organic frameworks on photocatalytic reaction selectivity on highly sensitive and durable Cu-CuBr substrate

Photocatalytic reactions using copper-based nanomaterials have emerged as a new paradigm in green technology. Selective photocatalysis is very important for improving energy utilization efficiency, and in order to directional improve catalytic selectivity, it is necessary to understand the mechanism of interfacial reactions at the molecular level. Therefore, a unique bifunctional Cu-CuBr substrate is first fabricated via an electrochemical method, which overcomes the instability of traditional copper-based materials and endows high surface-enhanced Raman spectroscopy (SERS) sensitivity and photocatalytic performance and can be stored stably for more than a year. Further modification of the surface with Metal-Organic Frameworks (MOFs) containing carboxyl functional groups can significantly tune the surface properties of the substrate. This increases the adsorption of cationic dyes to improve the SERS effect, and 10−10 M methylene blue can easily be detected with this substrate. Surprisingly, in-situ SERS monitoring of the interfacial photocatalytic dehalogenation reaction of aromatic halides through its intrinsic SERS effect reveal two competing selective reaction pathways, self-coupling and hydrogenation. Typically, the SERS spectra reveal that the latter's selectivity was greatly enhanced after MOFs modification, and the yield rate of the hydrogenated product increased from 27.6 % to 46.9 % (selectivity increased from 32.7 % to 51.5 %). This proves that the surface properties of catalysts, especially the affinity for reaction intermediates, can effectively regulate catalytic selectivity.

Adsorption of anionic and cationic azo dyes from wastewater using novel and effective multicomponent adsorbent

Water pollution is rising worldwide, necessitating innovative and effective treatment solutions. This study introduces a multicomponent/multifunctional novel nanocomposite synthesized from polyethyleneimine (PEI), graphene oxide (GO), bentonite clay, and MgFeAl-layered triple hydroxide (LTH), termed as AGO/Bentonite/LTH. In this study, the synthesized AGO/Bentonite/LTH nanocomposite was utilized to remove azo dyes (methyl orange and crystal violet) from contaminated water samples. The novel AGO/Bentonite/LTH nanocomposite was benchmarked against its pristine materials and their binary combinations. The results indicated the superior adsorption performance of the AGO/Bentonite/LTH nanocomposite relative to all other adsorbents synthesized and examined herein. All the synthesized adsorbents were characterized using different techniques in order to reveal their textural properties, functional groups, morphology, thermal stability, and crystallinity before applying them to decontaminate wastewater samples contaminated with methyl orange (MO) and crystal violet (CV). The Langmuir adsorption isotherm model predicted that the maximum adsorption capacities of CV and MO onto the AGO/Bentonite/LTH nanocomposite are 1705.1 and 1171.8 mg/g, respectively. On the other hand, zeta potential, pH, and FTIR studies suggested the existence of multiple mechanisms governing the adsorption of CV and MO onto the AGO/Bentonite/LTH nanocomposite. Thermodynamic results indicated the endothermicity and exothermicity of CV and MO adsorption, respectively. Another interesting finding reported herein is the high reusability of this nanocomposite as demonstrated by the minimal reduction in the removal of these two pollutants with the repetitive use of the nanocomposite. Additionally, the nanocomposite can also be easily and cheaply regenerated via a few rinses with a diluted NaOH aqueous solution. These interesting observations suggest that the synthesized AGO/Bentonite/LTH nanocomposite is a potent material for efficient dye removal from contaminated water bodies.

Adsorbents prepared from epoxy-based porous materials of microcrystalline cellulose for excellent adsorption of anionic and cationic dyes

It reported a porous material prepared from microcrystalline cellulose (MCC), to achieve rapid preparation of adsorbents. The porous material was characterized by several tools including 1H NMR, FTIR, XPS, and SEM. Two adsorbents were prepared and subjected to adsorption experiments. Dye adsorption experiments show that the adsorption driving is electrostatic interactions and the process is chemisorption. The maximum capacity of Microcrystalline cellulose-g-Poly (glycidyl methacrylate)-Tannins (MPT) reached 191.3 (Methylene blue), 123.7 mg g−1 (Rhodamine B), and Microcrystalline cellulose-g-Poly (glycidyl methacrylate)-Lysine (MPL) attained 425.8 (Methylene blue), 480.7 mg g−1 (Methyl orange). The results were followed the pseudo-second-order (PSO) and agreed with the Langmuir fit model. Adsorption-desorption cycling experiments further indicate that the adsorbent possesses outstanding reproducibility. At last, epoxidized bio-porous materials are positive in the preparation of dye adsorbents with critical adsorption properties.

Polypyrrole-decorated bentonite magnetic nanocomposite: A green approach for adsorption of anionic methyl orange and cationic crystal violet dyes from contaminated water

In the presented study, a novel polypyrrole-decorated bentonite magnetic nanocomposite (MBnPPy) was synthesized for efficient removal of both anionic methyl orange (MO) and cationic crystal violet (CV) dyes from contaminated water. The synthesis of this novel adsorbent involved a two-step process: the magnetization of bentonite followed by its modification through in-situ chemical polymerization. The adsorbent was characterized by SEM/EDX, TEM/SAED, BET, TGA/DTA-DTG, FTIR, VSM, and XRD studies. The investigation of the adsorption properties of MBnPPy was focused on optimizing various parameters, such as dye concentration, medium pH, dosage, contact time, and temperature. The optimal conditions were established as follows: dye concentration of Co (CV/MO) at 100 mg/L, MBnPPy dosage at 2.0 g/L, equilibrium time set at 105 min for MO and 120 min for CV, medium pH adjusted to 5.0 for MO dye and 8.0 for CV dye, and a constant temperature of 303.15 K. The different kinetic and isotherm models were applied to fit the experimental results, and it was observed that the Pseudo-2nd-order kinetics and Langmuir adsorption isotherm were the best-fitted models. The maximal monolayer adsorption capacities of the adsorbent were found to be 78.74 mg/g and 98.04 mg/g (at 303.15 K) for CV and MO, respectively. The adsorption process for both dyes was exothermic and spontaneous. Furthermore, a reasonably good regeneration ability of MBnPPy (>83.45%/82.65% for CV/MO) was noted for up to 5 adsorption-desorption cycles with little degradation. The advantages of facile synthesis, cost-effectiveness, non-toxicity, strong adsorption capabilities for both anionic and cationic dyes, and easy separability with an external magnetic field make MBnPPy novel.

Hydroxypropyl sulfonated starch and Asperlligus oryzae biomass for cationic dye adsorption: characterization, mechanism, sorption modelling

AbstractIn this work, hydroxypropyl starch sulfate (HPSS) and Aspergillus oryzae (Asp. oryzae) were successfully synthesized and investigated for aqueous methylene blue (MB) adsorption. The as-prepared adsorbents were also characterized extensively using FTIR, XRD, SEM, EDX, and BET surface area analyses to elucidate their functional, textural, and morphological properties. Also, the effects of initial dye concentration, contact time, and pH on the adsorption performance of both adsorbents were systematically investigated. Due to the significant surface area differences, the HPSS recorded a higher maximum adsorption capacity (qmax) of 52.41 mg/g at 20 mg/L initial concentration, 60 min, and pH 8.0, while the Asp. oryzae recorded a qmax of 37.26 mg/g at 20 mg/L initial concentration, 60 min, and pH 9.0. Specifically, the –SO3 groups on the HPSS shared some electrostatic affinity with the MB dye cationic center (N+ backbone), while a hydrogen bond is formed between the hydroxyl groups of the starch and N+ backbone of the MB dye. Also, the nitrogen- and oxygen-containing groups on the Asp. oryzae provided active sites for the binding of MB species. Also, the XRD spectra of the loaded HPSS showed a decrease in the sharp crystalline peaks, while no structural changes were observed in the case of loaded Asp. oryzae. Therefore, the effectiveness of the HPSS and Asp. oryzae for adsorbing MB was established in the study.

Construction of C8/threonine-functionalized mesoporous silica aerogel based on mixed-mode and its adsorption properties for both anionic and cationic dyes

High adsorption and desorption efficiencies for both anionic and cationic dyes are still a challenge for adsorbents to treat dyestuffs wastewater. In this study, the C8/threonine-functionalized mesoporous silica aerogel based on mixed-mode was constructed to overcome the challenge, with properties of hydrophobicity and switchable surface charge of n-octyl and threonine groups. With methylene blue and azophloxine as cationic and anionic dye models, batch tests were conducted. The consequences proofed the adsorption process was efficient and fast, and the highest adsorption quantities for methylene blue and azophloxine were estimated as 274.30 mg/g and 152.43 mg/g, respectively. Additionally, the adsorbent showed good removal efficiency and reusability. The desorption efficiencies exceeded 97% using low concentration HCl or NaOH as eluents. Mechanism investigation proved that adsorption process relied on hydrophobicity and electrostatic interactions. These results instructed that SG-C8/Thr was a promising adsorbent with excellent adsorption and desorption efficiencies for both anionic and cationic dyes.

Halloysite nanotubes (MHNTs) modified S-scheme g-C3N4/γ-Fe2O3 photocatalyst for enhancing charge separation and photocatalytic activity

Photocatalysis is a surface process and an increase in the adsorption of target molecules on the surface of a photocatalyst could be of prime necessity in the photodegradation efficiency enhancement of dyes. To attain such a purpose, this study equips g-C3N4 with pores-modified halloysite nanotubes (MHNTs), then gets it wrapped by γ-Fe2O3 nanoparticles with high specific surface area (SSA) and S-scheme mechanism through a one-pot synthesis and co-precipitation, respectively. Characterization of fabricated photocatalysts is conducted to detect physical, chemical, optical, magnetic, and electrical properties by XRD, FT-IR, XPS, FE-SEM, EDX+MAP, TEM, BET, DRS, PL, VSM, Photocurrent, and EIS analyses. This research introduces a novel, ternary nanocomposite (g-C3N4/MHNTs/γ-Fe2O3) with dual functionality towards adsorption of both anionic and cationic dyes. Modified halloysite nanotubes (MHNTs), due to predominant negative charges (Si-O) on their outer surface, perform a significant role in the separation of holes (h+) from the photocatalysts and higher adsorption in MB photodegradation. In contrast, the inner surface of MHNTs through positive charges of AL-OH is beneficial for the electron (e-) separation and MO treatment. MHNTs with mesopores structure (Mean pore diameter: 10.6 nm) and high specific surface area (76.25 m2/g) contribute to higher adsorption and rapid transfer of photoexcited charges to the surface of ternary photocatalyst (g-C3N4/MHNTs/γ-Fe2O3 – 59.06 m2/g). After adding γ-Fe2O3 to g-C3N4/MHNTs, band gap of g-C3N4/MHNTs/γ-Fe2O3 reduces to 2.70 eV from 2.85 eV of g-C3N4/MHNTs, indicating influential role of γ-Fe2O3 nanoparticles in shifting photocatalytic activity of the ternary photocatalyst towards larger wavelengths (≥ 900 nm), and real world’s application (under illumination of sunlight). Among fabricated photocatalysts, g-C3N4/MHNTs/γ-Fe2O3 excels at degrading both MB and MO with the efficiency of %99.99 in 60 min and %89.1 in 120 min, respectively. To recognize the photocatalytic mechanism of the ternary photocatalyst, a trapping experiment was utilized for detecting oxidizing radicals in the photocatalytic process and then a photocatalytic mechanism was proposed.

Modification of melamine sponge by solid-phase esterification of citric acid-polyvinyl alcohol and its selective adsorption for cationic dyes

In the work, the functionalized melamine sponge has been successfully prepared by an in-situ solid esterification reaction of poly (vinyl alcohol) (PVA) and citric acid (CA) monomers. The esterification products were evenly coated onto the surface of the sponge framework of the melamine sponge (MS) by the mild heat treatment. Characterization results showed that the as-prepared PVA/CA@MS was provided with a rich hydroxyl group and carboxyl groups due to the as-formed cross-linked hydrogel and the suspending carboxyl group derived from the citric acid monomer. Therefore, the as-prepared 3D PVA/CA@MS was employed as the specific adsorbent to remove cationic dyes due to its oxygen-containing group. The adsorption performance of 3D PVA/CA@MS for cationic methylene blue and methyl violet was systemically carried out by kinetic and isothermal adsorption investigation. The data analyses suggested that the adsorption for PVA/CA@MS for MB and MV followed Langmuir isotherm adsorption and the maximum experimental adsorption capacities were 137.6 and 262.5 mg•g−1, respectively. The pseudo-second-order adsorption kinetic model fitted well with the experimental data of the time-dependent adsorption process. Mechanistic studies indicated that the electrostatic interaction was the main driving force for the adsorption of cationic dyes. These results demonstrated that the as-fabricated 3D PVA/CA@MS with easy separation performance was an efficient adsorbent for the selective removal of cationic dyes.

Recyclable hydrolyzed polymers of intrinsic microporosity-1/Fe3O4 magnetic composites as adsorbents for selective cationic dye adsorption

Recyclable hydrolyzed polymers of intrinsic microporosity-1/Fe3O4 magnetic composites as adsorbents for selective cationic dye adsorption

Magnetic chitosan-functionalized waste carton biochar composites for efficient adsorption of anionic and cationic dyes

In this study, BC-CoFe2O4-CS magnetic composite was successfully prepared from waste cardboard and investigated as an efficient adsorbent for the removal of amaranth and methyl orange in aqueous solution. First, the fibers obtained from the cardboard waste were carbonized by a hydrothermal process to produce biochar. Subsequently, the final magnetic composites were synthesized by in situ growth and Schiff base crosslinking reactions. The composites were characterized by zeta potential, Brunauer–Emmett–Teller measurements, Fourier transform Infrared spectroscopy, Scanning electron microscopy, Energy dispersive spectrometer,X-ray Diffraction, Thermogravimetry analysis and Vibrating sample magnetometer. The effects of adsorbent dosage and initial solution pH on dye removal efficiency were studied. The results showed that the maximum adsorption capacity of amaranth could reach 500.6 mg·g−1 at pH = 2, the adsorbent dosage of 0.5 mg·ml−1, and methyl orange could reach 644.0 mg·g−1 at pH = 4, the adsorbent dosage of 0.5 mg·ml−1. The adsorption process followed the pseudo-second order kinetic models and Langmuir isotherm. BC-CoFe2O4-CS was easily separated from the aqueous solution due to the loading of CoFe2O4 magnetic nanoparticles. Besides, the BC-CoFe2O4-CS could be further used after the adsorption experiments with or without desorption and still showed good adsorption performance in the actual water samples. Therefore, it is expected that the composite material prepared from waste cartons can be used for the treatment of dye-containing wastewater due to its low cost, high efficiency, and simple application.