Adsorption Kinetics Of Dye Research Articles

Kinetics and Mechanism of Adsorption of Anionic Dyes on Montmorillonite Modified with Sodium Metasilicate

The mechanism of adsorption of anionic dyes on montmorillonite modified with sodium metasilicate is investigated. The kinetics of dye adsorption is approximated by a pseudo–second order model, and the adsorption isotherm is analyzed on the basis of the Langmuir and Dubinin–Radushkevich models. The value of average free energy of adsorption E > 8 kJ/mol for all studied dyes, testifying to a surface chemical reaction between dye molecules and protonated silanol and aluminol groups on the surface of the edges of the aluminosilicate layers of the mineral. The adsorption of dyes is directly proportional to the increase in the temperature, mass, and charge of the organic anion and is inversely proportional to the increase in the ionic strength of the solution.

Preparation of diameter-controlled free-standing MWCNT membranes and their application for dye adsorption.

The synthesis of multi-walled carbon nanotubes (MWCNTs) was carried out over different Ni-loaded metallic oxide catalyst nanoparticles and under different reduction times to control the outside diameter of the nanotubes. Moreover, high-purity, free-standing membranes were fabricated by a simple filtration of the as-grown MWCNTs. Furthermore, the dye-adsorption properties of the nanotubes depended on the diameter of the carbon nanotubes (CNTs). The adsorption isotherms and kinetics of anionic dyes could be described by Freundlich and pseudo-second-order models, respectively. Thermodynamic studies suggested that the adsorption processes were spontaneous and exothermic. This work provides new insights into the synthesis and application of MWCNTs with the selective adsorption properties of carbon-based materials for the removal of organic dyes.

The Influence of Electrolytes in the Adsorption Kinetics of Reactive BF-5G Blue Dye on Bone Char: A Mass Transfer Model

The Influence of Electrolytes in the Adsorption Kinetics of Reactive BF-5G Blue Dye on Bone Char: A Mass Transfer Model

Studying Effect of Modifying Nano-Mineral Adsorbents on Efficiency of Dye Removal from Industrial Effluents

In this research work, the potential capability of nano-clay and tonsil, as low-cost and domestic adsorbents, for the elimination of a cationic dye, (CR18) from contaminated water is investigated. The surface properties of the adsorbents are studied by means of the scanning electron microscopy (SEM) and X-ray diffraction techniques. The effects of the initial dye concentration, pH, stirring speed, contact time, and adsorbent dosage are investigated at 25 . The results obtained show that the dye adsorption data from the nano-clay and tonsil experiments fit well to the Langmuir and Freundlich isotherms, respectively. The results of dye adsorption kinetics demonstrate that the adsorption system follows a pseudo-second-order model with a satisfactory correlation value (R=99%).The adsorption thermodynamics is also studied, concluding that the adsorption process is spontaneous and physically controlled. Under the optimum conditions (pH of 7, stirring speed of 200 rpm, CR18 concentration of 30 ppm and contact time of 30 min), the adsorption capacities of the mixed adsorbents show the maximum adsorption efficiency at the tonsil:nano-clay weight ratio of 1:2.

Preparation and characterization of ionic and non-ionic surfactants impregnated κ-carrageenan hydrogel beads for investigation of the adsorptive mechanism of cationic dye to develop for biomedical applications

In this work, the κ-carrageenan (CRG) hydrogel beads were impregnated by polyethylene glycol tert-octylphenyl ether (Triton X-100, TTX), as a non-ionic surfactant, and sodium dodecylbenzene sulfonate (SDBS), as an ionic surfactant, in the presence of crosslinking agents of potassium chloride and aluminum chloride. The prepared hydrogel beads were examined by FTIR, XRD, SEM, BET, and TGA analysis, which well confirmed their successful impregnation by the surfactants. The results revealed that the spherical/cubic CRG-TTX hydrogels have a higher crystal structure and thermal resistance than spherical CRG-SDBS. It was demonstrated that the impregnation of CRG hydrogel beads with TXX and SDBS surfactants improves their adsorption behavior toward methylene blue (MB) from aqueous media. The surfactant amount significantly effects on adsorbent performance, whereas the best surfactant concentration was found to be half of the critical micellar concentration. The optimum concentration of adsorbents was obtained 1 g L−1, and the best removal efficiencies were achieved in the pH range of 4 to 8. The maximum adsorption capacity was obtained 482.15 mg g−1 and 469.57 at 45 °C for CRG-TTX and CRG-SDBS, respectively. The dye adsorption kinetics followed the pseudo-second-order kinetic model and the obtained adsorption experimental data were in good agreement with the Langmuir isotherm equation. Thermodynamic study indicated that the process was spontaneous in nature and endothermic. The polymeric microspheres can be employed to deliver drugs in a rate-controlled and sometimes targeted manner.

Investigation into the adsorption of methylene blue on the surface of a "core–shell" type catalyst for the Fenton system

The catalytic oxidation of organic substances, in particular by the Fenton method, is one of the effective methods of wastewater treatment. The oxidation efficiency is affected by the adsorption properties of the catalyst when using heterogeneous catalysts in the Fenton process. In this work, the adsorption kinetics of methylene blue dye from aqueous solutions of different concentrations on the surface of the synthesized nanostructured magnetosensitive catalyst CoFe2O4/SiO2/CoMnO2 was studied by spectrophotometric analysis and the kinetic parameters of the process were determined. The CoMnO2-based "core–shell" catalyst has a magnetically sensitive cobalt ferrite core coated with a protective layer of porous SiO2, on the surface of which clusters of cobalt and manganese oxides are placed as catalytic centers. The process of adsorption of methylene blue from an aqueous solution can be considered as a quasi-chemical reaction of displacement of solvent molecules from the adsorption layer by dye molecules. The equilibrium state is described by the Langmuir equation, in which the effective adsorption constant is the ratio of the equilibrium constants of the Langmuir interactions of the dye and the solvent, respectively, with the active center of the adsorbent. The limiting adsorption of methylene blue and the adsorption constant characterizing the affinity of the dye to the catalyst surface were determined. The specific area of the catalyst was calculated under the condition of a known landing plane of the dye molecule. The influence of the adsorption properties of the catalyst on the efficiency of the Fenton process was established.

2-Hydroxy-1, 4-napthoquinone solubilization, thermodynamics and adsorption kinetics with surfactant

• Lawsone-surfactant interactions established for the first time. • Lawsone deposited on the surface of glass with silver ions, CTAB in alkaline media. • Dye adsorption kinetics discussed with various adsorptions kinetic models. • Our findings would be helpful to enhance color fastness of dye in textile processes. 2-Hydroxy-1, 4-napthoquinone (lawsone) natural red–orange dye was extracted from fresh henna (Lawsonia inermis) leaves in an alkaline media. The lawsone-surfactant solubilization constants ( K LS ) were calculated for the first time by using cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium dodecyl sulphate (SDS). The standard free energy, concentration of solubilized lawsone and number of lawsone molecules solubilized into micelles were calculated and discussed. Surface excess, minimum surface area per molecule, surface pressure, free energy (adsorption and aggregation) and equilibrium constants of different states were determined from tensiometry. Different metal ions (Ag + , Co 2+ , Cu 2+ , Ni 2+ , Fe 3+ , Zn 2+ and Al 3+ ) were used to determine the complex forming ability with lawsone. Out of these, Ag + ions have strong binding capacity with lawsone. The adsorption of lawsone on the surface of glass with silver ions in presence of CTAB was also observed at pH ≥ 9.0. The pseudo-first, second-order kinetic equation, intraparticles diffusion and Elovich models were used to determine the kinetics of lawsone adsorption onto the surface of glass and a probable mechanism has been discussed. Lawsone adsorption followed second-order kinetic equation ( k 2 = 0.019 g·mg −1 ·min −1 ).

Preparation of novel chitosan polymeric nanocomposite as an efficient material for the removal of Acid Blue 25 from aqueous environment

A novel, sustainable chitosan polymeric nanocomposite (CS-PVA@CuO) was synthesized and subjected to the removal of acid blue 25 (AB25) from the aqueous environment. The influence of different variables such as pH, contact time, initial dye concentration, temperature, and adsorption kinetics has been examined in the batch adsorption process. The CS-PVA@CuO composite was systematically characterized by XRD, FTIR, SEM, and EDX analysis. The pseudo-first order (PFO), pseudo-second order (PSO), and intra-particle diffusion kinetics equations were used to examine the kinetic data of the adsorption process. The adsorption kinetics confirms that the PSO model was a more exact fit. Thermodynamics study typically revealed that the uptake of AB25 by the adsorbent is spontaneous and endothermic in nature. Remarkably, the results reveal the highest adsorption capacity of the CS-PVA@CuO was 171.4 mg/g at 313 K. To be specific, CS-PVA@CuO polymer nanocomposite can be effectively used as a suitable adsorbent material for the potential elimination of anionic AB25 dye from the aqueous solutions.

Green Synthesis of Flowers-Like Nanostructured Calcium Silicates: Kinetics and Adsorption Isotherms of Malachite Green Dye Removal from Polluted Water

Microwaves assisted synthesis of flowers-like nanostructured calcium silicates from marble sawing powder and silica fume wastes has been successfully done in a very short reaction time, energy saving and cost effective approach. XRD analysis of the synthesized powder showed that wollastonite; CaSiO 3 is the predominant phase. Cotton-like structures which composed mainly of coalescenced tiny cubes in the range of less than 1000 nm in size have been obtained as observed from FESEM images. The maximum monolayer adsorption capacity, q max at 30 °C of Malachite green was found to be 17.12 mg/g. Different parameters affect the adsorption process as; pH, sorbent dose, dye concentration and temperature was experimented. The kinetics studies indicated that the adsorption kinetics of MG dye on calcium silicate followed the pseudo- first order reaction. The experimental results also showed that the Malachite green adsorption is fitted better to Freundlich isotherm model. The dye adsorption process was spontaneous, exothermic reaction as indicated from thermodynamic studies. Diffusion model reveal that intra-particle diffusion mechanism was not the sole rate-limiting step in this adsorption.

Surface Characteristics and Rose Bengal Adsorption Studies of Carbon Nanospheres Synthesized via Atmospheric Combustion of Diesel

In this study, the carbon nanospheres were synthesized by burning diesel and then treated with hydrogen peroxide (H2O2). The results showed that H2O2 - carbon nanospheres has a higher surface area than carbon nanospheres and therefore it was chosen as an adsorbent surface to remove the Rose Bengal dye from aqueous solutions. The prepared carbon nanospheres were examined by FTIR, XRD, SEM, AFM, TGA, Raman spectroscopy, BET and EDX. The FTIR study reveals the presence of hydroxyl and carboxyl stretching vibration and weak peaks belong to CH3, CH2 and C=C. Results obtained by Raman and XRD analysis are in good agreement thereby indicating the amorphous structure of the carbon nanospheres. Also, SEM images confirm the presence of soot materials as spherical and semispherical nanoparticles with diameter in the range (31-78 nm). Surface roughness calculated from AFM data provided evidence that spiky appearance on both carbon surfaces. TGA data indicate that both carbon samples are thermally unstable. BET and BJH results indicate that the treated sample possesses the highest surface area and mean pore diameter. EDX analysis indicated the presence of pure carbon nanosphere (treated sample) without any contamination. Also, the adsorptive removal of Rose Bengal on synthesized carbon nanospheres was studied. The isotherm adsorption results were found to be described fitted by the Freundlich rather than the Langmuir and Temkin models. Furthermore, the kinetics of dye adsorption were applied better by the pseudo-second-order model.

Kinetic Study of Adsorption of Malachite Green Dye on Poly Aniline-Formaldehyde/Chitosan Composite

Poly aniline-formaldehyde/chitosan composite (PAFC) was prepared by the in situ polymerization method. It was characterized by FTIR spectroscopy in addition to SEM, EDS and TGA techniques. The adsorption kinetics of malachite green dye (MG) on (PAFC) were studied for various initial concentrations (20, 30 and 40) mg/L at three temperatures (308, 313 and 318) K. The influence factors of adsorption; adsorbent dose, contact time, initial concentration and temperature were investigated. The kinetic studies confirmed that adsorption of MG obeyed the pseudo-second-order model and the adsorption can be controlled through external mass transfer followed by intraparticle diffusion mass transfer. A study of the temperature effect was indicated that the adsorption process was endothermic. The activation energy value for each concentration of the dye was calculated, it is observed that it decreases with increasing initial dye concentration.

Study of Kinetics and Adsorption Isotherm of Methylene Blue Dye using Tannin Gel from Ceriops tagal

Research on the equilibrium and adsorption kinetics of methylene blue dye using tannin gel from the Tingi tree (Ceriops tagal) has been carried out. This study aims to determine the capacity and adsorption kinetics of tannin gel against methylene blue dye. Several parameters, such as the effect of contact time, pH, and methylene blue dye concentration on adsorption, were also studied. Based on the research results, the optimum adsorption process is a contact time of 30 minutes and a pH of 7. The adsorption capacity increased to a concentration of 80 mg/L with a maximum adsorption capacity (qm) of 49.261 mg/g. The adsorption process follows the pseudo-second-order adsorption kinetics model and the Langmuir isotherm model.

Equilibrium and Kinetic Studies of a Cationic Dye Adsorption Onto Raw Clay

In this study, methylene blue (MB) dye adsorption from the aqueous solution on raw clay samples collected from the Tilkitepe in the east of Lake Van was presented. Batch adsorption studies were conducted to evaluate the effect of various experimental parameters such as pH, contact time and initial concentrations on the removal of MB. The five nonlinear adsorption equations were applied to describe the equilibrium isotherms. Considering the correlation coefficients, the order of the most suitable isotherm models was Sips> Freundlich> Temkin> Dubinin- Radushkevich>Langmuir. From the data applied to the pseudo-first-second order, Elovich and intra-particle diffusion kinetic models, it can be said that the best model describing the kinetics of MB dye adsorption is the pseudo-second order (PSO) kinetic model. The results are shown that Tilkitepe / Van raw clay material could be used as an economical and effective adsorbent for dye removal.

Adsorption of Reactive Blue 4 Dye onto Chitosan 10B in Aqueous Solution: Kinetic Modeling and Isotherm Analysis

The reactive blue 4 (RB4) dye adsorption onto chitosan 10B was studied in aqueous solution as a function of contact time, dye concentrations, ionic strength, temperature and solution pHs. The dye adsorption kinetics validated a pseudo second-order model while the rate determining step followed intraparticle diffusion mechanism. The equilibrium dye adsorption isotherms were nicely fitted with the Langmuir model. The maximum amount of dye uptake onto chitosan 10B was found to be 95.24 μmol/g. The mean adsorption energy (E) from the Dubinin–Radushkevich isotherm, the activation energy (Ea) from Arrhenius equation and apparent thermodynamic parameters such as changes in standard free energy (∆G°), standard enthalpy (∆H°) and standard entropy (∆S°) indicate that the present adsorption is a spontaneous endothermic physisorption process. Desorption of RB4 from dye-loaded chitosan was tested in NaOH solution (pH 13) and the chitosan flakes can be reused.

Evaluations of physico-chemical properties of TiO2/clinoptilolite synthesized via three methods on photocatalytic degradation of crystal violet

Different preparation routes for TiO 2 -supported natural and synthetic clinoptilolite (TiO 2 /CP) composites were thoroughly investigated on the basis of sol–gel, hydrothermal, and in-situ hydrothermal methods. The micro-structural features and physicochemical properties of resultant TiO 2 /CPs were characterized via X-ray diffraction patterns, scanning (transmission) electron microscope images, Fourier transform infrared spectra, inductively coupled plasma-optical emission spectrometry methods, BET-isotherms, UV–visible spectra, and surface charge potential distributions. The results showed that in-situ hydrothermal method led to well dispersions of loaded-TiO 2 particles on the surface of leaf-like CP, while obviously aggregated TiO 2 on a relatively distorted structure of CP was obtained using sol–gel and hydrothermal methods. Their adsorptive and photocatalytic efficiencies for removal of crystal violet (CV) dye in aqueous solution were also explored under UV-irradiations. The results demonstrated that TiO 2 /CPs synthesized via sol–gel and in-situ hydrothermal methods presented the excellent performances with 98% removal efficiencies as compare to the bare commercial TiO 2 which achieved 53% removal of CV dye. While, the in-situ hydrothermally synthesized TiO 2 /CPs were the best due to their moderate energy cost, highest adsorption capacities and removal efficiencies. Particularly, the synthetic CPs as supports exhibited synergetic photocatalytic activities for the degradation of CV dye, which is attributed to their high surface areas, better adsorption capability, and fine dispersion of TiO 2 particles. Adsorption and degradation kinetics of CV dye were found to follow the pseudo-second and pseudo-first order models, respectively.

Peptide-Based Gel in Environmental Remediation: Removal of Toxic Organic Dyes and Hazardous Pb2+ and Cd2+ Ions from Wastewater and Oil Spill Recovery.

A dipeptide-based synthetic amphiphile bearing a myristyl chain has been found to form hydrogels in the pH range 6.9-8.5 and organogels in various organic solvents including petroleum ether, diesel, kerosene, and petrol. These organogels and hydrogels have been thoroughly studied and characterized by different techniques including high-resolution transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and rheology. It has been found that the xerogel obtained from the peptide gelator can trap various toxic organic dyes from wastewater efficiently. Moreover, the hydrogel has been used to remove toxic heavy metal ions Pb2+ and Cd2+ from wastewater. Dye adsorption kinetics has been studied, and it has been fitted by using the Freundlich isotherm equation. Interestingly, the gelator amphiphilic peptide gels fuel oil, kerosene, diesel, and petrol in a biphasic mixture of salt water and oil within a few seconds. This indicates that these gels not only may find application in oil spill recovery but also can be used to remove toxic organic dyes and hazardous toxic metal ions from wastewater. Moreover, the gelator can be recycled several times without significant loss of activity, suggesting the sustainability of this new gelator. This holds future promise for environmental remediation by using peptide-based gelators.

Willow Lignin Recovered from Hot-Water Extraction for the Production of Hydrogels and Thermoplastic Blends.

A blend of commercial willow cultivars (Salix spp.) was subjected to hydrothermal pretreatment: hot-water extraction in a pilot plant 65-ft3 digester. Lignin recovered from the autohydrolyzate (willow lignin, WL) was used to produce hydrogels and thermoplastic blends. Lignin-kaolin-acrylamide (WL 10.7 % w/w) and lignin-poly(ethylene)glycol diglycidyl ether (WL 66.7 % w/w) hydrogels exhibited favorable adsorption and absorption properties, respectively. Dye adsorption kinetics, swelling capacities, fragrance emanation, and compression moduli were measured for the hydrogels, along with SEM characterization. Additionally, WL was esterified by acetylation (C2 , WAc) and acylation with lauroyl chloride (C12 , WFAE and WFAEH ). The crude and esterified lignin samples were blended (1-12 % w/w) with polylactic acid (PLA) via lab-scale melt extrusion to produce thermoplastic blends. The physicochemical properties of the blends were evaluated. They exhibited an increase in degradation temperature and UV absorbance with potential to hinder photodegradation of PLA and may be leveraged in packaging applications.

Study of the Dye Adsorption Kinetics of Metal–Organic Frameworks in Aqueous Media

Water can easily be contaminated by many dye molecules because of its high solubility with dense color. Dye‐contaminated water requires purification via the adsorptive removal of dye molecules, employing various porous materials. To increase the removal efficiency and selectivity, demands for developing new metal–organic frameworks (MOFs) for dye removal continue to increase. Herein, we present a study on the dye‐adsorption properties of MOFs based on their structures and pore sizes. The effects of dye molecule charge and size were also investigated. Three different MOFs (Universitetet i Oslo; UiO‐66, UiO‐67, Materials of Institute Lavoisier; MIL‐100 [Fe]) and four dye molecules (Methylene Blue, Rhodamine B, Tropaeolin O, and Amaranth) were employed. The results suggest that the surface properties and framework structure of the MOFs affect dye adsorption capacity and kinetics, as characterized by UV–Vis spectroscopy and adsorption kinetics analysis. These results provide opportunities for the development of MOFs for dye removal from aqueous solution.

Brilliant Green Dye Biosorption Using Activated Carbon Derived from Guava Tree Wood

The removal of brilliant green (BG) dye from an aqueous solution using activated carbon (AC) derived from guava tree wood is conducted in batch conditions. The influence of different factors such as contact time, pH, adsorbent dosage, initial dye concentration, and temperature on the adsorption of BG onto AC was investigated. FTIR, BET, and SEM analyses were performed to determine the characteristics of the material. The isotherm results were analyzed using the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherms. Linear regression was used to fit the experimental data. It was found that the equilibrium data are best represented by the Freundlich isotherm, and the adsorption capacity (qe) was 90 mg dye/g AC. The values of the free energy (∆G), enthalpy (∆H), and entropy (∆S) were −86.188 kJ/mol, 43.025 kJ/mol, and 128 J/mol.K, respectively, at pH 7 for the BG dye. The kinetics of BG dye adsorption were analyzed using pseudo-first-order and pseudo-second-order models, and it was found that the pseudo-second-order model was suitable for the behavior of the BG dye at R2 = 0.999.

Eco-friendly synthesis of ZnO nanoparticles using Cannabis sativa and assessment of its activities as efficient dyes removal and antioxidant agent

ABSTRACT In reported work, zinc oxide nanoparticles (ZnONPs) had been synthesised by a green method using aqueous extract of Cannabis sativa leaves. A facile, eco-friendly, time saving and beneficial procedure for the preparation of metal nanoparticles had been developed. UV-visible spectroscopy, Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to characterise the ZnONPs composition, their shape, size and crystallinity. Ultraviolet-visible spectra showed the absorbance band between 300 and 400 nm, which indicated the synthesis of stable ZnO nanoparticles. Average size of ZnONPs was calculated from XRD as 46 nm. SEM and EDX spectra confirmed the synthesis of spherical shaped ZnONPs. FTIR spectra showed that different functional groups were present in aqueous extract of plant’s leaves, which acted as reducing agents in the formation of stable ZnONPs. The value of DPPH radical inhibition percentage shown by ZnONPs was 88 ± 0.08% at 1500 µg/ml concentration revealing its good antioxidant activity. The total antioxidant activity calculated for ZnONPs was 0.521 ± 0.34 against BHT as standard. Total phenolic contents for ZnONPs was calculated to be 292.60 ± 1.12 mg/g GAE. Then the synthesised ZnONPs were utilised as catalyst for the removal of harmful organic dyes methylene blue (MB) and Congo red (CR). Various factors like adsorbent dosage, dye concentration, pH and temperature were studied and optimised for maximum removal of dyes. Pseudo-first-order model was followed for adsorption kinetics of both dyes. Adsorption isotherms were also assessed using Freundlich and Langmuir isotherm models. Hence, green approach was easy and cost effective for the removal of organic dyes and found as efficient antioxidant in current study.