Removal of Basic Red 46 dye from aqueous solution by adsorption and photocatalysis: equilibrium,isotherms, kinetics,and thermodynamic studies

ABSTRACT

In this study, the main objective is the elimination of Basic Red 46 dye by coupling two processes, adsorption on activated clay followed by photocatalysis over ZnO as photocatalyst. The adsorption was investigated under different conditions of pH, adsorbent dose, dye concentrations, and temperature. The best adsorption yield occurs at neutral pH ~ 7 within 60 min with an uptake percentage of 97% for a concentration of 25 mg/L and a dose of 0.5 g/L. The results at equilibrium were successfully described by the Langmuir model with an adsorption capacity of 175 mg/g. To investigate the mechanism of dye adsorption characteristic, the adsorption constants were determined using pseudo first order, pseudo second-order and intraparticle diffusion model. It was found that the Basic Red 46 dye adsorption is well described by the pseudo second-order kinetic. The second part of this work was dedicated to the photodegradation onto ZnO under solar irradiation of the residual BR 46 concentration, remained after adsorption. For the remaining concentrations, the removal yields reach 100% under.     

Adsorption equilibria between dye and surfactant in single and binary systems onto geological materials

Adsorption characteristics of cationic dyes and surfactants onto clay and sandstone from a single component system were studied using toluidine blue (TB) and cetyl trimethylammonium bromide (CTAB). Equilibrium data of TB and CTAB in the single solute systems fit well to the Langmuir and the Freundlich adsorption isotherms. Competitive adsorption was observed between dye and surfactant cations. The effect of sodium chloride on dye and surfactant adsorption was studied in TB–NaCl and CTAB–NaCl binary systems. Equilibrium adsorption for binary systems was analyzed by using the extended Langmuir and the extended Freundlich models. Adsorption results for the TB–CTAB system onto both adsorbents were also well described by the Sheindorf–Rebuhn–Sheintuch (SRS) model for multi-component systems. Free energy changes for adsorption systems were calculated using thermodynamic equilibrium constants evaluated from selectivity coefficients of the binary systems. The site distribution functions estimated using Freundlich model parameters gave valuable information about the ratio of the adsorption sites on adsorbent surface having different affinity for competing cations.     

Adsorption of malachite green onto bentonite: Equilibrium and kinetic studies and process design

The adsorption of malachite green onto bentonite in a batch adsorber has been studied. The effects of contact time, initial pH and initial dye concentration on the malachite green adsorption by the bentonite have been studied. Malachite green removal was seen to increase with increasing contact time until equilibrium and initial dye concentration, and the adsorption capacity of bentonite was independent of initial pH in the range 3–11. Four kinetic models, the pseudo first- and second-order equations, the Elovich equation and the intraparticle diffusion equation, were selected to follow the adsorption process. Kinetic parameters; rate constants, equilibrium adsorption capacities and correlation coefficients, for each kinetic equation were calculated and discussed. It was shown that the adsorption of malachite green onto bentonite could be described by the pseudo second-order equation. The experimental isotherm data were analyzed using the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich equations. Adsorption of malachite green onto bentonite followed the Langmuir isotherm. The thermodynamic parameters, such as ΔH, ΔS and ΔG, were also determined and evaluated. A single stage batch adsorber was designed for different adsorbent mass/treated effluent volume ratios using the Langmuir isotherm.     

Surfactant‐modified feldspar: Isotherm,kinetic, and thermodynamic of binary system dye removal

In this article, surface modification of feldspar using hexadecyltrimethyl ammonium bromide (HDTMA) and its dye removal ability in single and binary systems was studied. Acid Black 1 (AB1) and Acid Red 14 (AR14) were used as model dyes. The monocomponent Langmuir isotherm model was applied to experimental data and the isotherm constants were calculated for both dyes. The monolayer coverage capacities of surfactant‐modified feldspar (HDTMA‐feldspar) for AB1 and AR14 dyes in single solution system were found as 6.369 mg/g and 3.984 mg/g, respectively. It was observed that the equilibrium uptake amounts of AB1 and AR14 dye in binary mixture onto sorbent decreased with increasing concentrations of the other dye resulting in their antagonistic effect. Equilibrium adsorption for binary systems was analyzed by using the Extended Langmuir and Jain and Snoeyink Modified Extended Langmuir models. The rate of kinetic processes of single and binary dye systems onto adsorbent was described by using two kinetics adsorption models. The pseudo‐second‐order model was the best choice among the kinetic models to describe the adsorption behavior of single and binary dyes onto HDTMA‐feldspar. Thermodynamic parameters showed that dye adsorption on HDTMA‐feldspar were exothermic and unspontaneous in nature. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Comparative studies of functionalized polyacrylamide/graphite composites for the removal of direct blue 2b from aqueous solution

In this study, we prepared glucose and glucosamine-grafted polyacrylamide (PAM)/graphite composites as adsorbents and characterized by Fourier transform infrared (FT-IR), SEM/EDAX, XRD and TGA analysis. Direct blue 2b dye removal by composites was investigated using kinetic, equilibrium and thermodynamic studies by varying adsorption parameters. The results manifest that glucosamine-grafted PAM/graphite composite was an efficient adsorbent for the expulsion of dye from aqueous medium. The Freundlich isotherm fits well with the equilibrium data. The pseudo second-order model was suitable for describing the kinetic data and equilibrium attained within 60 min. Thermodynamic analysis reveals that adsorption of dye is physical, spontaneous and endothermic in nature. The recyclability study reveals that the regeneration efficiency of GA-g-PAM/graphite was maintained 85.35% up to eight cycles.     

Adsorption of anionic dyes on poly(epicholorohydrin dimethylamine) modified bentonite in single and mixed dye solutions

The performance of poly(epicholorohydrin dimethylamine) modified bentonite (EPIDMA/bentonite) as an adsorbent to remove anionic dyes, namely Direct Fast Scarlet, Eosin Y and Reactive Violet K-3R, was investigated in single, binary and ternary dye systems. In adsorption experiments in single dye solutions, the adsorption of the three dyes onto EPIDMA/bentonite was described by the Langmuir isotherm model and the pseudo-second-order kinetic model. At low dosage of EPIDMA/bentonite, preferential adsorption was observed for the dye with higher affinity to the adsorbent in mixed dye systems. The reduction in uptake of the dye with increasing equilibrium dye concentration in the isotherm and desorption in the kinetic curves were observed for the dye with lower affinity. The total amount of dyes adsorbed versus the total equilibrium dye concentrations were fitted well by the Langmuir isotherm model. The kinetics of the total adsorbed amount of dyes followed the pseudo-second-order kinetic model. The effect of the dosage of adsorbent on color removal efficiency, residual color distribution and adsorption kinetics was investigated.     

竹制活性炭处理酸性染料废水吸附等温线模型的误差分析(英文)

High surface area activated carbons were produced by thermal activation of waste bamboo scaffolding with phosphoric acid.Single component equilibrium dye adsorption was conducted on the carbons produced and compared with a commercially available carbon.Two acid dyes with different molecular sizes,namely Acid Yellow 117(AY117) and Acid Blue 25(AB25),were used to evaluate the adsorption capacity of the produced carbons.It was found that the dye with smaller molecular size,AB 25,was readily adsorbed onto the produced carbon,nearly three times higher than a commercially available carbon,while the larger size dye,AY117,showed little adsorption.The experimental data were analyzed using isotherm equations including Langmuir,Freundlich,Tempkin,Toth,Redlich-Peterson and Sips equations.The equilibrium data were then analyzed using five different non-linear error analysis methods.     

Adsorption kinetics and mechanism of acid dye onto montmorillonite from aqueous solutions: Stopped-flow measurements

The adsorption of acid dye, namely, acid fuchsin (AF), onto sodium montmorillonite (Na⁺-Mt) from aqueous solutions was investigated. The adsorption process was very fast and attained equilibrium within 1 h, which was an economically favorable requisite. The Freundlich and Langmuir adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were calculated. The experimental data fit well with Freundlich model rather than the Langmuir model. The equilibrium adsorption constant, K_c, was determined and used to calculate the enthalpy and entropy of the adsorption process. The adsorption kinetics was followed up using a stopped-flow spectrophotometer under pseudo-first-order conditions. The influence of initial dye concentrations, amount of sodium montmorillonite, and temperature on the rate of adsorption were studied. The activation energy of adsorption was calculated and indicated a chemical adsorption process. The enthalpy of adsorption confirmed an exothermic process. A proper mechanism for adsorption supported by X-ray and atomic absorption data was proposed.     

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

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, secondorder 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)).     

EFFECT OF TEMPERATURE ON THE ADSORPTION OF METHYLENE BLUE DYE ONTO SULFURIC ACID–TREATED ORANGE PEEL

The present study explains the preparation and application of sulfuric acid–treated orange peel (STOP) as a new low-cost adsorbent in the removal of methylene blue (MB) dye from its aqueous solution. The effects of temperature on the operating parameters such as solution pH, adsorbent dose, initial MB dye concentration, and contact time were investigated for the removal of MB dye using STOP. The maximum adsorption of MB dye onto STOP took place in the following experimental conditions: pH of 8.0, adsorbent dose of 0.4 g, contact time of 45 min, and temperature of 30°C. The adsorption equilibrium data were tested by applying both the Langmuir and Freundlich isotherm models. It is observed that the Freundlich isotherm model fitted better than the Langmuir isotherm model, indicating multilayer adsorption, at all studied temperatures. The adsorption kinetic results showed that the pseudo-second-order model was more suitable to explain the adsorption of MB dye onto STOP. The adsorption mechanism results showed that the adsorption process was controlled by both the internal and external diffusion of MB dye molecules. The values of free energy change (ΔG ^o) and enthalpy change (ΔH ^o) indicated the spontaneous, feasible, and exothermic nature of the adsorption process. The maximum monolayer adsorption capacity of STOP was also compared with other low-cost adsorbents, and it was found that STOP was a better adsorbent for MB dye removal.     

Adsorption of Bezanyl Red and Nylomine Green from aqueous solutions by natural and acid-activated bentonite

The adsorption of two acid dyes, namely, Red Bezanyl and Green Nylomine, onto natural bentonite and acid activated bentonite from aqueous solutions were studied in a batch system. The kinetic data show that at the equilibrium, the acid-activated bentonite fixes more Bezanyl Red and Nylomine Green than the natural bentonite. Adsorption equilibrium was reached within 2 h. The results also showed that the kinetics of adsorption is best descibed by a pseudo second-order expression than a first or second-order model. Adsorption isotherms of acid dyes onto bentonite and acid-activated bentonite were determined and correlated with common isotherm equations such as the Langmuir and Freundlich models. The Langmuir model agrees very well with the experimental data. For better explanation of these results, the natural bentonite and acid-activated bentonite have been examined in detail through FTIR, BET and XRD analyses.     

Removal of basic and acid dyes from aqueous solutions by a waste containing boron impurity

In this study, batch experiments were carried out for the sorption of basic blue 41 (BB 41), and acid blue 225 (AB 225) onto boron waste (BW) from boron enrichment plant. The operating variables studied are the initial dye concentration, contact time, solution pH, and adsorbent dosage. The experimental equilibrium data were analyzed by using various adsorption isotherm models and the results have shown that the adsorption behavior of AB 225 and BB 41 could be described well reasonably by Langmuir and Temkin isotherms, respectively. Kinetics studies indicated that the adsorption of both dyes follow pseudo-second-order kinetics. The sorption of basic dye increased at high pH values, whereas the opposite was true for acidic dye. The results indicate that BW could be employed as low-cost alternatives to the commercially available adsorbents in wastewater treatment for the removal of acid and basic dyes.     

The Removal of Textile Dyes with Cross-Linked Chitosan-Poly(acrylamide) Adsorbent Hydrogels

This study examined the behaviors and mechanisms of chitosan (CS)-poly(acrylamide) (PAAM) full interpenetrating polymeric network (IPN) hydrogels as an adsorbent to remove EY-4GL and S-Blue textile dyes from an aqueous solution. CS-PAAM IPN hydrogels were prepared by acrylamide monomer polymerization in the presence of a natural polymer, e.g., chitosan. N,N′-methylenebisacrylamide (MBAM) and glutaraldehyde (GLA) were selected to cross-link PAAM and CS chains and a full-IPN structure formed simultaneously. Kinetic swelling studies of CS-PAAM IPNs were carried out with deionized water and aqueous dye solutions. The experimental data clearly suggested that the swelling process obeys second-order kinetics. Network and diffusion parameters for CS-PAAM and PAAM hydrogels were calculated and it was observed that these IPN hydrogels have high cross-linking efficiencies in comparison to PAAM hydrogels. Adsorption of textile dyes onto hydrogels was studied by a batch adsorption technique at 23°C and 40°C, and it was seen that the higher temperature increased the dye adsorption onto the hydrogels. L type (Lan gmuir) adsorption isotherms, according to Giles classification system, were established at the end of adsorption experiments. The prepared IPN hydrogels show good ability to uptake textile dyes from wastewater.     

Adsorption performance of mesoporous silicas towards a cationic dye. Influence of mesostructure on adsorption capacity

The dye adsorption performance of four mesoporous silicas with different structure and textural properties, MCM-41, MCM-48, SBA-15 and mesocellular silica foam (MCF), was studied and compared by using toluidine blue O (TBO) as dye model in aqueous solution. These materials were characterized by X-ray diffraction (XRD), small-angle X-ray scattering, nitrogen adsorption-desorption analyses, and transmission electron microscopy (TEM). The effect of some parameters such as adsorbent dosage, contact time, temperature, and pH on the TBO removal in aqueous solution was studied. Results showed that adsorption capacity raised when adsorbent dosage, contact time and pH solution were increased while an increase in temperature decreased the adsorption of TBO. Langmuir, Freundlich and Temkin isotherm models were employed to elucidate the adsorption mechanism while the adsorption rate data were analyzed according to the pseudo-first and second-order kinetic models. Results showed that adsorption of TBO onto MCM-48, SBA-15, and MCF fitted well the Freundlich isotherm model while the kinetic studies showed that adsorption process could be better described by the pseudo-second-order model for all mesoporous silicas. Finally, some solvents were evaluated to carried out dye desorption from the TBO-loaded mesoporous silicas founding that acetic acid was the most efficient.     

Removal of Indigo Carmine and Pb(II) Ion from Aqueous Solution by Polyaniline

In this work, we report the synthesis of polyaniline emaraldine salt (PAni-ES) by a chemical oxidative polymerization method. The obtained PAni-ES samples prepared under different conditions were used for the removal of indigo carmine anionic dye and Pb(II) ion from aqueous solutions. The results also showed that the pseudo–second-order kinetic model fitted better than the data obtained from pseudo–first-order model for the adsorption of anionic dye and Pb(II) ion onto PAni-ES. The fit of the data for indigo carmine and Pb(II) ion adsorption onto PAni-ES suggested that the Langmuir model gave closer fittings than Freundlich model.     

Adsorption d'un colorant textile réactif sur un biosorbant non‐conventionnel : Les fibres de Posidonia oceanica (L.) delile

The marine biomaterial Posidonia oceanica (L.) fibres were used as a novel low‐cost biological adsorbent for the removal of reactive textile dye (Cibacron Red) from aqueous solutions. Batch experiments were carried out for sorption kinetics and isotherms. Operating variables studied were contact time, fibres quantity, temperature, pH, and chemical pre‐treatment. The equilibrium state was reached within 48 h. Biosorption capacity seems to be enhanced by increasing the biosorbent mass. Rising the temperature has also a positive effect on dye removal rate. Maximum colour removal was observed at pH 5.5. Pre‐treating fibres with H₃PO₄ and HNO₃ solutions increased considerably the adsorption capacity. Kinetic and equilibrium data for raw fibres were well described by the pseudo‐second order and Freundlich models, respectively. Besides, the thermodynamic study has showed that the dye‐adsorption phenomenon onto P. oceanica biomass was favourable, endothermic and spontaneous.     

Palladium,silver, and zinc oxide nanoparticles loaded on activated carbon as adsorbent for removal of bromophenol red from aqueous solution

The adsorption of bromophenol red (BPR) onto three adsorbents including palladium, silver and zinc oxide nanoparticles loaded on activated carbon (Pd-NP-AC, Ag-NP-AC and ZnO-NP-AC) in a batch system has been studied and the influence of various parameters has been optimized. The influence of time on removal of BPR on all adsorbent was investigated and experimental data were analyzed by four kinetic models including pseudo first and second-order, Elovich and the intraparticle diffusion equations. Following fitting the experimental data to these models, the respective parameters of each model such as rate constants, equilibrium adsorption capacities and correlation coefficients for each model were investigated and based on well known criterion their applicability was judged. It was seen that the adsorption of BPR onto all adsorbents sufficiently described by the pseudo second-order equation in addition to interparticle diffusion model. The adsorption of BPR on all adsorbent was investigated at various concentration of dye and the experimental equilibrium data were analyzed and fitted to the Langmuir, Freundlich, Tempkin, Dubinin, and Radushkevich equations. A single stage in batch process was efficient and suitable for all adsorbents using the Langmuir isotherm with maximum adsorption of 143 mg g^?1 for Pd-NP-AC, 250 mg g^?1 for Ag-NP-AC and 200 mg g^?1 for ZnO-NR-AC. Thermodynamic parameters such as ΔG°, ΔH°, and ΔS° for Pd-NP-AC adsorbent were calculated.     

Preparation of methacrylamide grafted and dye-ligand immobilized PET fibers: Studies of adsorption and purification of lysozyme

In this study, novel affinity chromatographic fibers was prepared from methacrylamide grafted poly(ethylene terephthalate), PET-g-pMAA, using benzoylperoxide as an initiator. A dye ligand (i.e., Procion Brown) as a ligand was then covalently immobilized on the different amount of pMAAm grafted PET fibers, (PET-g-pMAAm-PB). The fibers were characterized by surface area measurement, infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Adsorptive properties of the composite fibers were tested using a model protein (i.e., lysozyme). To achieve these purposes, the influence of pH, ionic strength, initial lysozyme concentration, and temperature on adsorption system has been investigated and evaluated. A maximum lysozyme adsorption PET-g-pMAAm-PB fiber was obtained as 43.9 mg g⁻¹ at pH 7.5. The experimental equilibrium data obtained for lysozyme adsorption onto PET-g-pMAAm-PB fibers fitted well to the Langmuir isotherm model. The result of kinetic analyzed for lysozyme adsorption onto affinity fibers showed that the second-order rate equation was favorable. The purity of the eluted lysozyme, as determined by HPLC, was 84% with recovery 73% for PET-g-pMAAm-PB fiber. Experiments on regeneration and dynamic adsorption were also performed. It appears that PET-g-pMAAm-PB fibers can be applied for lysozyme separation without causing any denaturation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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.