Removal of Anionic Dyes from Water using Citrus limonum (Lemon) Peel: Equilibrium Studies and Kinetic Modeling

Abstract

The present study was undertaken to evaluate the adsorption potential of Citrus limonum (lemon) peel as an adsorbent for the removal of two anionic dyes, Methyl orange (MO) and Congo red (CR) from aqueous solutions. The adsorption was studied as a function of contact time, initial concentration, and temperature by batch method. The adsorption capacities of lemon peel adsorbent for dyes were found 50.3 and 34.5 mg/g for MO and CR, respectively. The equilibrium adsorption data was well described by the Langmuir model. Three simplified kinetic models viz. pseudo-first-order, pseudo-second-order, and Weber and Morris intraparticle diffusion model were tested to describe the adsorption process. Kinetic parameters, rate constants, equilibrium sorption capacities, and related correlation coefficients for each kinetic model were determined. It was found that the present system of dyes adsorption on lemon peel adsorbent could be described more favorably by the pseudo-first-order kinetic model. The results of the present study reveal that lemon peel adsorbent can be fruitfully utilized as an inexpensive adsorbent for dyes removal from effluents.     

Uptake of anionic and cationic dyes by highly effective porous carbon adsorber based on industrial processing residues

In this work, we investigated the performance of porous carbon prepared from carob (Ceratonia siliqua L.) processing residues at optimized conditions for the removal of the Basic Green 4 (BG4) and Direct Red 28 (DR28) dyes from aqueous solutions. The influence of several parameters such as adsorbent dose, initial dye concentration, contact time and temperature was evaluated in batch adsorption experiments. Maximum adsorption capacities were observed as 769 mg g^?1 and 323 mg g^?1 for BG4 and DR28, respectively. These results suggest that BG4 and DR28 could be removed using a novel porous carbon from carob processing residues.     

Adsorption of different dyes from aqueous solution using Si-MCM-41 having very high surface area

Adsorption characteristics of four different dyes Safranin O (cationic), Neutral Red (neutral), Congo Red (anionic) and Reactive Red 2 (anionic) on Si-MCM-41 material having very high surface area are reported. The surface morphology of Si-MCM-41 material before and after adsorbing dye molecules are characterised by FTIR, HRXRD, nitrogen adsorption–desorption isotherms, FESEM, and HRTEM. The adsorption capacities of Si-MCM-41 for the dyes followed a decreasing order of NR > SF > CR > RR2. The adsorption kinetics, isotherm and thermodynamic parameters are investigated in detail for these dyes using calcined Si-MCM-41. The kinetics and isotherm data showed that both SF and NR adsorb more rapidly than CR and RR2, in accordance with pseudo-second-order kinetics model as well as intraparticle diffusion kinetics model and Langmuir adsorption isotherm model respectively. The thermodynamic data suggest that the dye uptake process is spontaneous. The high adsorption capacities of dyes on Si-MCM-41 (q_m = 275.5 mg g^?1 for SF, q_m = 288.2 mg g^?1 for NR) is explained on the basis of electrostatic interactions as well as H-bonding interactions between adsorbent and adsorbate molecules. Good regeneration capacity is another important aspect of the material that makes it potent for the uptake of dyes from aqueous solution.     

Synthesis of a Magnetic Co@C Material via the Design of a MOF Precursor for Efficient and Selective Adsorption of Water Pollutants

3D metal–organic frameworks (MOFs) can be appropriate templates for the fabrication of nanomaterials due to they have active sites exposed on the channel or surface, which thus provide them with improved catalytic performance. In this study, a 3D cobalt-based MOF [Co(H₂bpta)]_n (Co-MOF), where H₄bpta denotes 2,2′,4,4′-biphenyltetracarboxylic acid, has been constructed with the use of a ligand with a high carbon content. On this basis, a 2D magnetic carbon-coated cobalt nanoparticle composite (Co@C) was prepared by using the title MOF under different temperatures. Magnetic Co@C can readily absorb dye from the solution and can thus act as an inexpensive and fast-acting adsorbent. Moreover, we have explored the adsorption isotherms, kinetics and thermodynamics of the anion dyes in detail. The adsorption capacity of the Co@C-800 for investigated methyl orange (MO) and congo red (CR) dyes were 773.48 and 495.66 mg g^?1, respectively. It is noteworthy that MO adsorption is higher in existing materials. Thermodynamic studies suggest that the adsorption processes are spontaneous and exothermic. This study opens a new insight into the synthesis and application of carbon-based materials that enable the selective removal of organic dyes.

Graphical Abstract

A Co-MOF has been solvothermal synthesized and structurally characterized, which was used as a combined catalyst and carbon source for the synthesis of magnetic Co@C. Interestingly, the as-grown Co@C-800 exhibits high-performance selective adsorption of anionic dyes (MO and CR) with high adsorption capacities.

     

Graphene Oxide/ Polyacrylic acid-based double network skeleton for enhanced cationic dye adsorption

ABSTRACT

A three-dimensional (3D) porous graphene oxide/polyacrylic acid (GO/PAA) aerogel with double network skeleton was assembled by in situ solution polymerization method toward removing multi-cationic dyes from wastewater, such as methylene blue (MB), crystal violet (CV), methyl orange (MO), and rhodamine B (RhB), in which the adsorption capacities for CV and MB were 851.31 and 771.14 mg g^?1, respectively. This composite showed outstanding adsorption capacity due to the structure of 3D double network skeleton, large specific surface area, and remarkable carboxyl group content.     

Template-free synthesis of MgO mesoporous nanofibers with superior adsorption for fluoride and Congo red

MgO mesoporous nanofibers were obtained by a template-free electrospinning method. The unique bumpy-structure was obtained on the surface of nanofibers that could enhance the surface area and provide more active sites for adsorption. The formation mechanism of the bumpy-structure has been investigated. The as-prepared MgO nanofibers with a high surface area of 194.17?m² g^?1 exhibited excellent adsorption capacities for fluoride of 237.49?mg?g^?1. Furthermore, the MgO nanofibers showed selective adsorption for different organic dyes and have superior adsorption capacity for Congo red (4802.27?mg?g^?1). The adsorption processes for both fluoride and Congo red were systematically investigated, which were found to follow the pseudo-second-order kinetic model. By comparison with the reported fabrication routes and adsorption capacities of mesoporous MgO, the synthesis process is simple, controllable and template-free, and the superior adsorption performance provided a potential adsorbent for the removal of fluoride and Congo red in wastewater treatment. The high surface area of the MgO mesoporous nanofibers might also promote its application in basic catalysis and other fields.     

Highly Efficient Adsorption of Anionic Dyes from Aqueous Solutions Using Sawdust Modified by Cationic Surfactant of Cetyltrimethylammonium Bromide

In the present study, the adsorption behavior of Congo Red (CR) dye from aqueous systems onto sawdust modified by cetyltrimethylammonium bromide, CH₃(CH₂)₁₅N(CH₃)₃Br (CTAB) was attempted. Adsorption experiments were carried out using both batch and column modes under various operating conditions. The effects of some important parameters such as solution pH, adsorbent dosage, initial dye concentration and contact time were investigated. Treatment of the equilibrium data obtained in batch experiments was carried out using Langmuir and Freundlich isotherm equations. Based on the isotherm analysis, it was found that the adsorption of CR dye onto SD fits well to the Langmuir model and the adsorption pattern on CTAB modified sawdust (CTAB/SD) followed the Freundlich isotherm which is indicative of heterogeneity of the adsorption sites on the surfactant-modified sawdust. The maximum adsorption capacity of SD and CTAB/SD were found to be 5.2 and 9.1?mg?g^?1, respectively, according to the Langmuir model. However, much higher differences in sorption capacities were observed for CTAB/SD and SD in the column system (66.73?mg?g^?1). In order to find out the possibility of the exhausted column for frequent use, a regeneration study was also carried out. It was found that the dye uploaded column can be easily regenerated with a high performance using ethanol as the washing solution.     

Application of copper sulfide nanoparticles loaded activated carbon for simultaneous adsorption of ternary dyes: Response surface methodology

Copper sulfide nanoparticles were synthesized and loaded on activated carbon (CuS-NPs-AC) for ternary dye removal. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) were used to characterize the synthesized materials. The performance of the materials was subsequently evaluated for simultaneous ultrasound assisted adsorption of Disulphine Blue (DB), Eosin Yellow (EY) and Safranin O (SO) dyes in ternary solution under different conditions that include variation in solution pH, initial concentrations of dyes, sonication time and adsorbent dosage. Response surface methodology (RSM) using central composite design (CCD) was employed to obtain the optimum experimental conditions. The maximum removal efficacies (88.39%, 68.49% and 55.69% for DB, EY and SO, respectively) were found at the optimum conditions: 3.63 min of sonication time, 0.02 g of CuS-NPs-AC, 7.76mg L^-1 of DB, 8.89mg L^-1 of EY, 9.87mg L^-1 of SO and pH 6.5. Very high adsorbent capacities of 198.12, 165.0, 139.58mg g^-1 for DB, EY and SO, respectively, were yielded from Langmuir isotherm as best fitted model. Kinetic study indicated that the pseudo-second-order kinetic model was well fitted to the experimental data of ternary adsorption process. The results of the study display very good adsorption efficiency of the synthesized adsorbent for dye removal with high adsorption capacity under optimum conditions.     

Application of ecological adsorbent in the removal of reactive dyes from textile effluents

BACKGROUND: The capacity and mechanism of adsorption of the reactive dyes monoazo (RR2) and diazo (RR141), using a new adsorbent with a strong ecological appeal developed from the sludge of the textile effluent treatment process, were investigated. The kinetics and adsorption isotherms were determined at different temperatures and salt concentrations. After determination of the best experimental conditions for adsorption for both dyes, tests were carried out in fixed‐bed adsorption columns. RESULTS: For both dyes, there was a reduction in the adsorption capacity of the adsorbent developed when the system operated at temperatures above 40 °C. When 10% (by mass) of sodium chloride was added to the adsorbate RR141 the maximum adsorption increased from 66.67 mg g^?1 to 78.74 mg g^?1. For both dyes, the addition of sodium sulfate did not favor significantly the adsorption. The results obtained for scale‐up of the laboratory data for the adsorption columns indicated that the operating time with reactive dye diazo is 43.5% longer than that for monoazo. CONCLUSION: The adsorbent studied was shown to be a very promising alternative in terms of an environmentally friendly process. Copyright © 2009 Society of Chemical Industry     

Role of unburnt carbon in adsorption of dyes on fly ash

Various fly ash samples with different unburnt carbon contents were collected, characterised and tested for adsorption of basic dyes, Methylene Blue and Crystal Violet, in aqueous solution. It was found that unburnt carbon plays a major role in dye adsorption. The mineral matter of fly ash has little adsorption capacity and most of the adsorption capacity of fly ash can be attributed to the unburnt carbon. The fly ash with higher unburnt carbon content will have higher adsorption capacity. For the carbon‐free fly ash, adsorption capacities for Methylene Blue and Crystal Violet are only 2 × 10^?6 mol g^?1 and 1.0 × 10^?6 mol g^?1, respectively, while the adsorption capacities for Methylene Blue and Crystal Violet on carbon‐enriched fly ash are 1.2 × 10^?4 mol g^?1 and 1.0 × 10^?4 mol g^?1, respectively. A two‐site Langmuir adsorption model best describes the adsorption isotherm. Copyright © 2005 Society of Chemical Industry     

Adsorption of Congo Red from Aqueous Solutions Using Chitosan Hydrogel Beads Formed by Various Anionic Surfactants

The structural organization of chitosan hydrogel beads (CSBs) formed by various anionic surfactants, sodium dodecyl sulfate (SDS), sodium decyl sulfate (DS), dodecyl benzenesulfonic acid sodium salt (SDBS), and dioctyl sulfosuccinate sodium salt (DSS), and their applications as adsorbents for environmental purifications were investigated using Congo red (CR) as a model dye. The adsorption capacities of CSB as a function of surfactant concentration revealed that CSBs formed by 5 g/L anionic surfactant were the most effective for CR adsorption. The structure of CSBs and their adsorption capacities for CR depend on the nature of anionic surfactants. The maximum adsorption capacities of CSB_SDS, CSB_DS, CSB_SDBS, and CSB_DSS obtained from the Langmuir isotherm model were 186.02, 209.28, 207.25, and 113.83 mg/g, respectively, indicating that CSB_DS was the best adsorbent for CR.     

Synthesis,physical properties,and application of aminated poly(glycidyl methacrylate)/zeolite composite

Poly(glycidyl methacrylate)/zeolite (PGMA/Z) composite was prepared by free radical polymerization and it was further modified to contain amino groups on its surface, by reacting to hexamethylenediamine. FTIR, TG, and SEM analyses were performed and investigated its potential as an adsorbent for removal of anionic dyes; namely, Reactive Red 120 (RR120) and Reactive Blue 4 (RB4). The effect of operational parameters was investigated. Maximum RR120 and RB4 adsorption capacities of composite were calculated as 136.5 and 189.8 mg g⁻¹, respectively. Isotherm, kinetic, and thermodynamic studies were also performed. It was found that the adsorption process might be heterogeneous by nature, and adsorption kinetics of reactive dyes followed the pseudo‐second order. The thermodynamic calculations showed that adsorption process was spontaneous and exothermic. POLYM. COMPOS., 37:2313–2322, 2016. © 2015 Society of Plastics Engineers     

Removal of Congo red from aqueous solution using a chitosan/organo‐ montmorillonite nanocomposite

To further improve the adsorption capacity of chitosan (CTS), a series of novel chitosan/organo‐montmorillonite nanocomposites (CTS/OMMT) were synthesized and the adsorption abilities for Congo red (CR) investigated in this study. The nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the results indicated that an exfoliated nanostructure was formed in CTS/OMMT nanocomposites. Compared with the adsorption capacity of OMMT (192.4 mg g^?1), CTS/OMMT with an amount of cetyltrimethylammonium bromide equal to 0.75 CEC of MMT and molar ratio of CTS to OMMT of 1:10 exhibited the higher adsorption capacity (290.8 mg g^?1). The adsorption behaviours of OMMT and CTS/OMMT showed that the adsorption kinetics and isotherms were in good agreement with a pseudo‐second‐order equation and the Langmuir equation, respectively. The IR spectra revealed that a chemical interaction occurred between CTS/OMMT and CR. The adsorption capacity of CTS/OMMT nanocomposite was higher than that of other absorbents; this study suggested that the CTS/OMMT nanocomposite could be used as an adsorbent to remove CR dye from aqueous solution. Copyright © 2007 Society of Chemical Industry     

Investigation of synergistic adsorption between methyl orange and Cd(II) from binary mixtures on magnesium hydroxide modified clinoptilolite

The simultaneous removal of Methyl orange (MO) and Cd²⁺ (mainly from organo-metallic dyes) onto magnesium hydroxide modified clinoptilolite (MHMC) was described and compared to a single adsorbate situation. The adsorption performance was studied by batch experiments. The adsorption mechanism of MO and Cd²⁺ on MHMC was investigated. Langmuir and Dubinin-Raduskevich (D-R) isotherm successfully predicted the adsorption of MO and Cd²⁺ in single and binary systems. Maximum adsorption capacity calculated from Langmuir isotherm equation in single solution for MO and Cd²⁺ was 0.305 and 0.282mmol/g, respectively. In a binary system of MO/Cd²⁺, the adsorption capacity for both MO and Cd²⁺ was higher than in single solutions. The results indicated that the adsorption system of MO/Cd²⁺ presented a synergistic effect, not competitive adsorption, which suggested that MHMC can be used as an adsorbent for removal of dyes and heavy metal in the multi-solute system.     

Chitosan/polyaniline hybrid for the removal of cationic and anionic dyes from aqueous solutions

Nanostructured chitosan/polyaniline (CH/PANI) hybrid was synthesized via in situ polymerization of aniline in the presence of chitosan. The CH/PANI hybrid was characterized by FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. The CH/PANI hybrid had a nanofibrous structure with an average diameter of 70 nm. This hybrid was employed as an ecofriendly and efficient adsorbent with high adsorption capacity for the removal of Acid Green 25 (AG) and methylene blue (MB) from aqueous solutions. AG and MB were used as anionic and cationic model dyes, respectively. The CH/PANI adsorbent showed high dependence on the pH of the medium with an excellent adsorption performance and regeneration manner. The kinetics and adsorption isotherms were studied. The CH/PANI hybrid follows the pseudo second-order adsorption kinetics and Temkin isotherm model for the adsorption of both AG and MB dyes. This assumes that the enthalpy of dyes molecules decreases with the adsorption on heterogeneous surface with various kinds of adsorption sites and as well as the ability to form multilayers of the dye. Also, intraparticle diffusion was found to play an important role in the adsorption mechanism. The maximum adsorption capacity was found to be 240.4 mg g⁻¹ of AG at pH 4 and 81.3 mg g⁻¹ of MB at pH 11. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47056.     

Tailoring Chitosan/LTA Zeolite Hybrid Aerogels for Anionic and Cationic Dye Adsorption

Chitosan (CS) is largely employed in environmental applications as an adsorbent of anionic dyes, due to the presence in its chemical structure of amine groups that, if protonated, act as adsorbing sites for negatively charged molecules. Efficient adsorption of both cationic and anionic dyes is thus not achievable with a pristine chitosan adsorbent, but it requires the combination of two or more components. Here, we show that simultaneous adsorption of cationic and anionic dyes can be obtained by embedding Linde Type A (LTA) zeolite particles in a crosslinked CS-based aerogel. In order to optimize dye removal ability of the hybrid aerogel, we target the crosslinker concentration so that crosslinking is mainly activated during the thermal treatment after the fast freezing of the CS/LTA mixture. The adsorption of isotherms is obtained for different CS/LTA weight ratios and for different types of anionic and cationic dyes. Irrespective of the formulation, the Langmuir model was found to accurately describe the adsorption isotherms. The optimal tradeoff in the adsorption behavior was obtained with the CS/LTA aerogel (1:1 weight ratio), for which the maximum uptake of indigo carmine (anionic dye) and rhodamine 6G (cationic dye) is 103 and 43 mg g⁻¹, respectively. The behavior observed for the adsorption capacity and energy cannot be rationalized as a pure superposition of the two components, but suggests that reciprocal steric effects, chemical heterogeneity, and molecular interactions between CS and LTA zeolite particles play an important role.     

Adsorption of Water-Soluble Organic Dyes on Magnetic Charcoal

Magnetic charcoal was prepared by entrapment of fine charcoal particles into the structure of magnetic iron oxides. This adsorbent can efficiently adsorb a variety of organic compounds. For the adsorption experiments water soluble organic dyes belonging to the triphenylmethane, heteropolycyclic and azodye groups were used as model compounds. Maximum adsorption capacities ranged between 10 and 20 mg of dyes per 1 cm³ of the sedimented adsorbent; this corresponds to 132·5–265 mg of dyes per 1 g of the dried adsorbent. © 1997 SCI.     

Cellulose/polyaniline derivatives nanocomposites: Synthesis and their performance in removal of anionic dyes from simulated industrial effluents

A series of cellulose/polyaniline derivatives [polyaniline (PANI), poly(N‐methylaniline) (PNMANI), and poly(N‐ethylaniline) (PNEANI)] nanocomposites were synthesized by in situ chemical oxidation polymerization method and successfully applied for removal of acid red 4 and direct red 23 dyes from simulated industrial effluents. The synthesized nanocomposites were analyzed using Fourier transform infrared and ultraviolet‐visible spectroscopies, thermogravimetric analysis and scanning electron microscope. The effect of some parameters including pH, adsorbent amount, and initial dyes concentrations on adsorption processes were evaluated. The maximum adsorption capacities (Q_m) for the synthesized nanocomposites were calculated, and among them the Cell/PANI sample showed the highest Q_m for both AR4 (117 mg g^–1) and DR23 (56 mg g^–1) dyes. The regeneration and reusability tests exhibited that the synthesized nanocomposites had the relatively good reusability after five repetitions of the adsorption–desorption cycles. According to results, we envision that these nanocomposites, especially Cell/PANI, find application for removal of anionic dyes from industrial effluents mainly due to their low production costs, high adsorption effectiveness, and relatively good reusability. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45352.     

Cu2+ removal from aqueous solution by modified chitosan hydrogels

BACKGROUND: The adsorption of Cu²⁺ from aqueous solution using crosslinked chitosan hydrogels impregnated with Congo Red (CR) by ion‐imprint technology was systematically investigated with particular reference to the effects of contact time, pH, and initial concentration on adsorption. RESULTS: The adsorption capacity of the crosslinked chitosan without impregnation was only 68.68 mg g^?1 for Cu²⁺. However, the adsorption capacity increased from 77.42 (without imprint ion) to 84.54 mg g^?1 (imprint ion content 0.5 mmol) after the chitosan was impregnated with a ratio of 1/12 of CR to chitosan. The as‐prepared adsorbents were found to be pH‐dependent and the process of adsorption agreed well with the Freundlich isotherm. The loaded adsorbents could be regenerated and reused without the appreciable loss of capacity. CONCLUSION: Chitosan hydrogels impregnated with CR showed higher Cu²⁺ adsorption capacities compared with those prepared conventionally without imprint ion, and thus developed a good approach to increase Cu²⁺ adsorption efficiency in the treatment of waste‐water. Copyright © 2012 Society of Chemical Industry