Dye Adsorption Process Research Articles

Kinetika Adsorpsi Zat Warna Tartrazina Menggunakan Limbah Ampas Tahu sebagai Adsorben

It has been conducted a research about the utilization waste of tofu as adsorbent of tartrazine dye. Utilization waste of tofu as adsorption because tofu contains protein which has the power adsorption of amino acids that form a zwitter ion. The purpose of this study was to determine the adsorption process and adosrption kinetics model of tartrazine dye by waste of tofu as adsorbent. Making the adsorbent is done by making waste of tofu into powder with a size of 100 mesh. The method used in the analysis of tartrazine dye is using UV-Vis. Adsorption of of tartrazine dye using waste of tofu at concentrations of 50 ppm and a contact time of 80 minutes with weight adsorbent 0.3 g. The two isotherms were used that Langmuir isotherm and Freundlich isotherm, the adsorption studies of tartrazine dye adsorbent waste of tofu follow Freundlich adsorption isotherms with a correlation coefficient (R2) of 94.4%, KF is 0.0026 mg/g and n is 0.5621. Adsorption kinetics of of tartrazine dye adsorbent waste of tofu following the model of adsorption Ho pseudo-second order with a correlation coefficient (R2) of 100%, Xe is 1.7761 mg/g and k2,ads is -0.6550 g/mg minutes. The mechanism adsorption of of tartrazine dye with waste of tofu as adsorbent is chemisorpsi process.

Silver based hybrid nanocomposite: A novel antibacterial material for water cleansing

The synthesis, characterization, adsorption, and antibacterial activities of silver-based hybrid nanocomposite, Ag/Ag2O/ZrO2/GL, is being reported herein. The composite was synthesized by incorporating silver and zirconium oxides nanoparticles into organic framework derived from abundant fruit bearing medicinal plant leaves of Psidium guajava. The prepared composite was characterized by employing several spectroscopic and microscopic techniques to establish the morphology, and the functional sites at the surface. It was investigated for the adsorption of methylene blue dye from water which revealed that 2.0 g L−1 of Ag/Ag2O/ZrO2/GL could clean solution having 10–60 mg L−1 concentrations in 120 min contact time. The process of dye adsorption was found to be endothermic and spontaneous on the basis of thermodynamic parameters. The investigation further revealed that the Freundlich isotherm explained adsorption data satisfactorily. The reaction followed pseudo-second order kinetics and which was controlled by intraparticle diffusion step. The thermodynamics, isothermal, and kinetics studies suggest that combination of electrostatic and physical adsorption was responsible for the methylene blue removal from water by Ag/Ag2O/ZrO2/GL. The equilibrium partition coefficient and adsorption capacity were 50.6 L g−1 and 4.95 mg g−1, respectively at 10 mg L−1 concentration with significant reusability. The material showed significant antibacterial activity against Escherichia coli and Staphylococcus aureus.

Adsorption of dyes from water by Prunella vulgaris stem and subsequent fungal decolorization

The residue of herbaceous Prunella vulgaris stem (PVS) was evaluated as a potential adsorbent for dye removal, followed by fungal cultivation to achieve dye degradation on solid waste. PVS was analyzed in terms of nutritional composition such as fiber, ash, protein, and fat, which not only played a role in dye adsorption but also provided solid matrix for fungal growth. Five dyes, namely, crystal violet (CV), methylene blue (MB), reactive black 5 (RB), indigo carmine (IC), and direct red 80 (DR), were tested as adsorbates but only CV and MB were effectively adsorbed. Effect of sorbent dose, contact time, dye concentration, and NaCl on adsorption was investigated individually. Langmuir model was suitable for fitting MB adsorption, while adsorption of CV adopted the Freundlich model. The adsorption capacity was calculated to be 625 mg/g for CV and 303 mg/g for MB, respectively. The adsorption process of both dyes was spontaneous and endothermic, and the adsorption followed pseudo 2nd order kinetic model and film diffusion model. The dyed PVS was finally cultivated with fungus Pycnoporus sp., wherein efficient dye decolorization was attained under solid state fermentation. As such, PVS coupled with subsequent fungal degradation might serve as novel alternative for dye effluent treatment.

Spirobifluorene-based polymers of intrinsic microporosity for the adsorption of methylene blue from wastewater: effect of surfactants.

Owing to their high surface area and superior adsorption properties, spirobifluorene polymers of intrinsic microporosity (PIMs), namely PIM-SBF-Me (methyl) and PIM-SBF-tBu (tert-butyl), were used for the first time, to our knowledge, for the removal of methylene blue (MB) dye from wastewater. Spirobifluorene PIMs are known to have large surface area (can be up to 1100 m2 g−1) and have been previously used mainly for gas storage applications. Dispersion of the polymers in aqueous solution was challenging owing to their extreme hydrophobic nature leading to poor adsorption efficiency of MB. For this reason, cationic (cetyl-pyridinium chloride), anionic (sodium dodecyl sulfate; SDS) and non-ionic (Brij-35) surfactants were used and tested with the aim of enhancing the dispersion of the hydrophobic polymers in water and hence improving the adsorption efficiencies of the polymers. The effect of surfactant type and concentration were investigated. All surfactants offered a homogeneous dispersion of the polymers in the aqueous dye solution; however, the highest adsorption efficiency was obtained using an anionic surfactant (SDS) and this seems owing to the predominance of electrostatic interaction between its molecules and the positively charges dye molecules. Furthermore, the effect of polymer dosage and initial dye concentration on MB adsorption were also considered. The kinetic data for both polymers were well described by a pseudo-second-order model, while the Langmuir model better simulated the adsorption process of MB dye on PIM-SBF-Me and the Freundlich model was more suitable for PIM-SBF-tBu. Moreover, the maximum adsorption capacities recorded were 84.0 and 101.0 mg g−1 for PIM-SBF-Me and PIM-SBF-tBu, respectively. Reusability of both polymers was tested by performing three adsorption cycles and the results substantiate that both polymers can be effectively re-used with insignificant loss of their adsorption efficiency (%AE). These preliminary results suggested that incorporation of a surfactant to enhance the dispersion of hydrophobic polymers and adsorption of organic contaminants from wastewater is a simple and cost-effective approach that can be adapted for many other environmental applications.

Fe-ZSM-5 zeolite for efficient removal of basic Fuchsin dye from aqueous solutions: Synthesis, characterization and adsorption process optimization using BBD-RSM modeling

The current study reports the first use of Fe-ZSM-5 as a potential adsorbent for textile effluent purification. The Fe-ZSM-5 zeolite was synthesized through a hydrothermal method using tetrapropylammonium bromide as an organic structure-directing template for application as a binder for basic Fuchsin (BF) dye from aqueous media. SEM observations confirmed that Fe-ZSM-5 exhibits a granular shape with a quasi-hexagonal structure, which is in agreement with its crystallinity demonstrated by XRD analysis. FTIR analysis indicates the abundance of SiOH groups on the Fe-ZSM-5 surface. N2 adsorption-desorption measurement showed the microporous structure (pore size around 1.93 nm) of Fe-ZSM-5 with a BET surface area of 399 m2/g. The uptake performance of Fe-ZSM-5 zeolite for BF dye was systematically studied as a function of different operational parameters. The experimental adsorption data were in good agreement with pseudo-second-order kinetics and Langmuir isotherm with a maximum adsorbed amount of 251.87 mg/g. BF dye adsorption onto Fe-ZSM-5 was a spontaneous and endothermic phenomenon. The binding mechanism is attributed to electrostatic interactions combined with H-bonding. Further, the response surface modeling permits us to optimize BF dye adsorption process. The highest BF dye removal performance was found to be 99.6 % under optimum conditions of pH 5, Fe-ZSM-5 dose 0.75 g/L, initial BF concentration 10 mg/L for 120 min at 20 °C. The findings of this work revealed that Fe-ZSM-5 zeolite could be proposed as an alternative adsorbent with outstanding performance for BF dye removal from wastewaters.

Dyes adsorption, antifungal and antibacterial properties of metal loaded mesoporous silica: Effect of metal and calcination treatment

Mesoporous silica MCM-41 was synthesized hydrothermally and then impregnated by different transition metals (such as Cr, Cu, Fe and Zn). The modified materials in calcined and non-calcined forms were tested in the adsorption of OG and MB dyes in single and binary system. Effect of calcination, contact time, initial dye concentration and adsorbent mass were studied. Two kinetics models were applied the first and the second order kinetics as well as the Freundlich and Langmuir isotherms were tested. The obtained samples were also used as anti-bacterial and anti-fungal agents using gram negative (P.aeruginos and E coli), gram positive (B. cereus, and S. aureus) pathogenic clinical bacteria and pathogenic fungi (Candida albicans). The result confirms that the adsorption process of both dyes follows second-order kinetics and their equilibrium data were fitted well to the linear Langmuir model. The maximum adsorption capacity of OG and MB dyes was 200 mg/g and 166 mg/g for non-calcined and calcined Zn/MCM-41, respectively. The adsorption of a binary mixture showed that the both materials are selective. The best selectivity was obtained by non-calcined Zn/MCM-41 wherein the OG dye was predominantly adsorbed. The application of all samples as anti-bacterial and anti-fungal agents showed encouraging results, but the best results were obtained by non-calcined materials, particularly with Cu/MCM-41 and Zn/MCM-41.

Preparation, characterization and application of Fe-pillared bentonite to the removal of Coomassie blue dye from aqueous solutions

This study aims to prepare the sodium bentonite (Bent-Na) and the iron-pillared bentonite (PILC-Fe) and to evaluate its adsorption efficacy against Coomassie blue from aqueous solution. Results demonstrated that the PILC-Fe sample presents an increase in the basal distance d001 from 13.66 to 16.93 A. The presence of the Fe–O and FeOOH functional group band on PILC-Fe was confirmed by FTIR analysis. A clear increase has been observed of the specific surface area from 45.86 to 125.30 m2/g for Bent-Raw and PILC-Fe, respectively, and this increase is greater than 63%. Adsorption of CBB dye into Bent-Na and PILC-Fe was fast, and their adsorption equilibriums were reached within 15 and 5 min, respectively. The maximum adsorption capacity for CBB dye is 9.125 mg/g for PILC-Fe, whereas Bent-Na presents a lower adsorption capacity of around 6.848 mg/g. The maximum CBB dye adsorption rate was attained at pH 4.68 for both bentonites. It is observed a difference in the removal efficiency implying that the adsorption of CBB molecule dye was affected by the structure and functional groups of dyes. It is noticed that the adsorption process for CBB dye into Bent-Na and PILC-Fe was better fitted with the linear and nonlinear Langmuir model. The CBB dye kinetic adsorption is better fitted by the pseudo-second-order model. Thermodynamic study indicated the feasibility and spontaneity of the CCB dye adsorption process that was exothermic and physical in nature. A comprehensive adsorption and mechanism interaction study of CBB molecular structure onto PILC-Fe was appropriately discussed.

Kinetics, equilibrium, and thermodynamics of the blue 19 dye adsorption process using residual biomass attained from rice cultivation

Rice husk ash and rice husk are waste materials generated in the rice agro-industries. This study focuses on the possibility of using these materials as adsorbents for the removal of reactive blue dye 19. The adsorbents were characterized by employing the point of zero charge technique, scanning electron microscopy, X-ray microanalysis, and Fourier-transform infrared spectroscopy. The adsorption study was performed in a static system and by determining the influence of the initial concentration, adsorbent dose, initial pH, contact time, and temperature effect. The conditions of the removal process were established as being an initial pH 2, an adsorbent dose of 1 g/100 mL, and an equilibrium time of 120 min. A kinetic study was performed, and the data obtained for rice husk ash as regards blue dye 19 adsorption fitted best to the Bangham model, while those obtained for RH fitted best to the pseudo-second order and Bangham models. The equilibrium isotherms were analyzed by employing the Langmuir, Freundlich, Toth, and Sips models, and the Langmuir and Toth models proved to be the best representatives of blue dye 19 adsorption for both rice husk ash and rice husk. The thermodynamics of the adsorption process was studied, showing that the rice husk/blue dye 19 and rice husk ash/blue dye 19 removal systems were spontaneous and exothermic.

Remediation of Crystal Violet Dye Aqueous Solution Using Agro Waste Based Activated Carbon: Equilibrium and Kinetics Studies

Remediation of crystal violet (CV) dye aqueous solution was attempted using acid activated raphia hookeri seeds (AARHS) as adsorbent. Adsorption equilibrium and kinetics of CV dye uptake onto AARHS were examined in series of experimental runs, and effects of contact time and initial CV dye concentrations were investigated at different solution temperatures (303 K, 313 K and 323 K). Equilibrium and kinetic data modeling of the adsorption process was performed using selected theoretical methods. Four different forms of Langmuir (type I, II, III and IV) and Freundlich isotherms were considered for fitting the equilibrium data while zero order, first order, pseudo-first order (PFO), second order, types I, II, III and IV pseudo-second order (PSO) and intra-particle diffusion models were selected to describe the kinetics of the adsorption process. Error functions including coefficient of determination (R2), root mean square error (RMSE), chi square (χ2) and average relative error (ARE) were employed to reveal model of best fit. Results obtained from error value computations show that the equilibrium data best followed Freundlich isotherm, which indicates multilayer adsorption of CV dye onto AARHS. The calculated Freundlich’s adsorption intensity values at different temperatures reveal the favourability of the adsorption process. PSO type I, II and IV best fitted the kinetic data compared to other investigated models. Intra-particle diffusion plots depict that the adsorption process of CV dye onto AARHS is a two-step process and also, intra-particle diffusion is not the only rate-limiting step.

Efficient and sustainable treatment of anionic dye wastewaters using porous cationic diatomite

How to develop an effective and cheap adsorbent for removing dyes completely from wastewaters and avoid disable adsorbent secondary pollution have great challenges for green dye and dyeing industrial production. In order to realize this aim, in this work, the porous cationic diatomite was prepared for the first time by covalently immobilizing poly-epichlorohydrin-dimethylamine onto natural diatomite, and its adsorption characteristics and sustainable utilization were investigated. The results indicated that the immobilizing reaction was found to happen both on the surface of diatomite and the inner wall of its pores. Cationic diatomite possessed a high removal efficiency to anionic dyes. The batch dye adsorption processes were endothermic and spontaneous, and better consistent with pseudo-second-order kinetic model and Freundlich isotherm model. The completely colorless effluent solution could be obtained when cationic diatomite was used as fixed-bed adsorbent, and its maximum dye adsorption capacities were more than 200 and 3 times larger than that of natural diatomite and commercial activated carbon, respectively. Most importantly, the disabled cationic diatomite could be used in colored coatings as pigment and filler simultaneously, thereby avoiding secondary pollution. In conclusion, this study can provide a green viable solution for controlling pollution in dye and dyeing industrial production.

Bioadsorbent from Magnetic Activated Carbon Hybrid for Removal of Dye and Pesticide

AbstractA novel bioadsorbent has been developed based on the framework of activated carbon, Fe3O4 nanoparticles, and ascorbic acid (AA@Fe3O4 NPs@AC). The objective of this study was efficient adsorption of organic compounds such as dye and pesticide from aqueous solutions by AA@Fe3O4 NPs@AC adsorbent. The structure of AA@Fe3O4 NPs@AC was characterized by TEM, TGA, FTIR, VSM, XRD, BET and Zeta potential. Moreover, the adsorption process of dye and pesticide compounds on AA@Fe3O4 NPs@AC was systematically considered and was found which the pseudo‐second‐order kinetic equation and Langmuir isotherm model conformed. The maximum adsorption capacities of AA@Fe3O4 NPs@AC for methylene blue (MB) dye and acetamiprid pesticide compounds were 370.37 and 357.14 mg g−1, respectively that revealed excellent adsorption performance of AA@Fe3O4 NPs@AC adsorbent. On the other hand, with easy and high recovery of AA@Fe3O4 NPs@AC through magnetic separation has provided a simple and green method to enhance the efficiency of bio‐adsorbent for remove of dyes and pesticides from contaminated water.

Decolorization of Textile Dye by Halophilic Exiguobacterium sp.VK1: Biomass and Exopolysaccharide (EPS) Enhancement for Bioremediation of Malachite Green

AbstractThe salt pan soil screened for the exopolysaccharides (EPS) producing organisms for the decolourization textile dyes. The isolate was characterized and confirmed as Exiguobacterium sp. VK1 by 16S rRNA analysis. The enhanced production of EPS was obtained with the minimal medium which was supplemented with various carbon sources, and cassava peel which has shown a 5.9 fold increase in the EPS (7704.71 mg/L) production. Exiguobacterium sp. VK1 removed Malachite Green (MG) dye (684.38 mg/g) with the maximum biosorption capacity of 79.1% at pH 6 and 40°C. With the increased EPS production, by supplementing the cassava peel, the MG dye adsorption also increased up to 97.61%, when decolorized within 30 min by Exiguobacterium sp. VK1. It was found that Pseudo Second‐order kinetics and Freundlich isotherm is the best fit for the equilibrium adsorption process of MG dye by Exiguobacterium sp. VK1. The thermodynamic properties such as activation energy (12.993 kJ/mol), change in enthalpy (10.501 kJ/mol), change in entropy ‐254.07 J/(mol K) and change in Gibbs energy (84.945‐90.026 kJ/mol) were investigated by Arrhenius and Eyring equation using Pseudo‐second‐order kinetic model. The result revealed that the adsorption process was thermodynamically feasible.

Removal of anionic azo dyes from aqueous solutions by quaternary ammonium salt-functionalized fibers with adjustable surface microenvironments

Adsorption is one of the most effective methods to remove organic pollutants from water. A series of functionalized fiber adsorbents with cationic adsorption sites and different hydrophobic alkyl chains have been prepared by immobilizing quaternary ammonium salts (QASs) on polyacrylonitrile fiber (PANF). The hydrophobicities of these QAS-functionalized fibers were evaluated by water uptake and contact angle analysis. These fibers were employed to remove anionic azo dyes (methyl orange, alizarin yellow R and methyl red from water. The fiber with a twelve-carbon alkyl chain (designated PANQAS-12F) had the highest adsorption capacity for MO and the maximum adsorption capacity (Qe) is 1.82 mmol g-1. The PANQAS-12F dye adsorption process follows second-order kinetics and correlates with a Langmuir model. A possible adsorption mechanism that proposes electrostatic interactions as the primary interactive force and hydrophobic and weak hydrogen bonding interactions as secondary forces is presented. The QAS-functionalized fiber can be reused ten times while still maintaining a removal rate of 99% or higher. The QAS-functionalized fiber is also very suitable for continuous flow processes giving a MO removal rate of more than 90% for the treatment up to 1020 mL of MO-containing water. These QAS-functionalized fibers have very promising application potential.

Adsorption of Methylene Blue Dyes Using Pectin Membrane

Environmental pollution caused by methylene blue textile dyes is very dangerous for the aquatic environment and human health. To overcome this problem, various adsorbents have been developed for the processing of methylene blue liquid waste. This aim of this research is to know the ability of pectin membrane toward methylene blue dyes. Pectin is a biomaterial isolated from the plant cell walls. Pectin is an anionic polymer, many contain active groups which able to bind positive ions of methylene blue. This method of this research is an experimental method in the laboratory. Pectin adsorbent membrane was made by dissolving of pectin into a 5% acetic acid solution. The optimal condition of the adsorption of methylene blue by pectin membrane was determine. The functional groups of pectin membranes were analyzed by infra red spectroscopy. The adsorption of methylene blue was analysis by using Ultraviolet-Visible Spectroscopy. The characterization of FTIR showed that pectin membranes have carboxyl and hydroxyl active groups. The results showed that the optimum condition of the adsorption process of methylene blue dye was within pH 4 with adsorption capacity of 0.75 mg/g and 60 minutes of contact time with adsorption capacity 17.64 mg/g. The optimum adsorption capacity of pectin membranes in adsorbing methylene blue was 19.39 mg /g

Enhancement of Adsorption of Magenta Dye by Immobilized Laccase on Functionalized Biosynthesized Activated Carbon Nanotubes

In the present study, laccase was immobilized over on activated carbon nanotubes (ACNTs) prepared from Prosopis juliflora bark (PJB) to improve good stability, reusability, and its adsorption performance of magenta dye. The immobilized laccase-ACNTs were characterized by scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR). The efficiency of magenta dye (MD) adsorption process was investigated in batch adsorption experiments. Response surface methodology (RSM)-based Box-Behnken design (BBD) was used to optimize the parameters, and the maximum MD adsorption was achieved around 95% at 120 min. The obtained results revealed that the immobilized laccase-ACNTs are a promising composite for degradation of textile dyes.

Sono-assisted enhanced adsorption of eriochrome Black-T dye onto a novel polymeric nanocomposite: kinetic, isotherm, and response surface methodology optimization

Nowadays, the colored wastewater generated primarily from dyeing and textile industries loaded with synthetic dyes are considered to be one of the key reason for water pollution. However, the remarkable development in material science resulted to fabrication of highly efficient composite materials for effective remediation of such wastewaters. In recent times, polymer matrix-based nanocomposites have turned out to be an outstanding domain of research considering the potential application of polymeric nanocomposite in several important areas including environmental remediation. In this work, the fabrication of a novel iron oxide/polyaniline polymeric nanocomposite (Iron oxide-PANI-PNC) was reported and its sono-assisted adsorptive potential was studied for a toxic anionic dye, Eriochrome Black-T (EBT). This study clears that pure iron oxide has strong pH dependency and it shows maximum dye adsorption only at highly acidic conditions. However, Iron oxide-PANI-PNC could reduce this pH dependency significantly and this polymeric nano-composite shows enhanced dye removal in the wide range of pH from 2.0 to 5.0. Langmuir isotherm model was best fitted to EBT dye adsorption experimental data onto Iron oxide-PANI-PNC with a maximum monolayer adsorption capacity of 285.71 mg/g. Sono-assisted EBT dye adsorption process has achieved an enhanced removal efficiency of 93% as compared to magnetic stirring (65%) and batch stirring (60%). Response surface methodology (RSM) based optimization revealed that maximum EBT dye uptake adsorption of 99.61% at Iron oxide-PANI-PNC dose of 0.8 g/L, sonication time of 27 min, and initial EBT dye concentration of 30 mg/L.

Modification of rice husk silica with bovine serum albumin (BSA) for improvement in adsorption of metanil yellow dye

In the present research, bovine serum albumin-modified silica from rice husk has been prepared and examined as adsorbent for removal of the metanil yellow dye. The silica was obtained by purification of silica from the rice husk. Rice husk was heated up at 700 °C for 4 h, the obtained rice husk ash was mixed with NaOH 5% and acidified with HNO3 10% to obtain silica. The modification was carried out by reacting silica with bovine serum albumin, and the amine-functionalized rice husk silica was obtained. The rice husk silica and amine-functionalized rice husk silica were characterized by Fourier-transform infrared, X-ray fluorescence, scanning electron microscopy, and Brunauer–Emmett–Teller. The adsorption study was conducted using batch method and investigated some parameters such as pH, adsorbate concentration, contact time, and temperature. The maximum adsorption capacity of rice husk silica and amine-functionalized rice husk silica was 25.975 and 82.345 mg/g, respectively. The adsorption process of metanil yellow dye onto rice husk silica followed Langmuir isotherm model. Besides, the adsorption of metanil yellow dye onto amine-functionalized rice husk silica was fitted to both Langmuir and Freundlich isotherm models (R2 = 0.99). The kinetic data were well described by the pseudo-second-order (R2 = 0.99) indicated a chemisorption process. The thermodynamic equation showed that the adsorption of metanil yellow dye onto rice husk silica was spontaneous through an endothermic reaction, while the adsorption onto amine-functionalized rice husk silica was spontaneous through exothermic reaction.

Adsorption of acid orange 7 using green synthesized CaO/CeO2 composite: An insight into kinetics, equilibrium, thermodynamics, mass transfer and statistical models

The present research reported the co-precipitation mediated synthesis of mixed metallic oxide composite, CaO/CeO2 using ultrasound-assisted extract of Eichhornia crassipes leaves. Fourier Transform Infrared Spectroscopy (FT-IR), Thermo-gravimetric/Differential Thermal analysis (TG/DTA), X-ray Diffraction (XRD), and Brunauer-Emmet-Tellet (BET) isotherms ensured the formation of the mixed oxide. Further, the CaO/CeO2 composite was tested in the anionic azo dye, Acid Orange 7 (AO7) removal process. The optimal removal of 92.68% was attained in the initial solution pH of 2.0 with the composite dosage of 0.1 g for 10 mg/L of AO7 concentration, operating at the temperature of 301 K. Response Surface Methodology (RSM) and Artificial Neural Network (ANN) techniques were employed to model the dye removal process. A second-order quadratic model from Box-Behnken Design (BBD) predicted and optimized the dye removal percentage with high degree of statistical accuracy (Fcal > Ftab at df=9; p < 0.0001). Likewise, a three-layered ANN model using the Levenberg–Marquardt backpropagation algorithm well predicted the dye adsorption process with the least root mean square error values (RMSE 0.3020). Further, the mean impact value (MIV) method identified pH0 as the most influential batch variable in the AO7 dye adsorption process.

Use of the β-Cyclodextrin Additive as a Good Alternative for the Substitution of Environmentally Harmful Additives in Industrial Dyeing Processes

In this work, the substitution of environmentally harmful additives in the industrial dyeing process of polyamide-6 microfiber-made knitted fabrics (PA-6µFKF) was studied. Using the disperse red 60 (DR60) dye, kinetic adsorption tests on the PA-6µFKF dyeing were performed by using either β-cyclodextrin (β-CD) additive, commercial leveling agents, or without additives. Equilibrium tests were also performed during 25 h. A modelling based on a dye adsorption process controlled by an intraparticle diffusion was proposed to represent the sets of kinetic data. Three isotherm models were also tested for representing the equilibrium data. The kinetic data have evidenced three main dye diffusion zones. Different adsorption mechanisms on PA-6µFKF surface dyeing was evidenced, being the data well represented by the two-step Langmuir isotherm. Finally, the best quality on color uniformity was attained using the β-CD additive, revealing a good alternative for the substitution of environmentally harmful additives in industrial dyeing processes.

Removal of malachite green using carboxymethyl cellulose-g-polyacrylamide/montmorillonite nanocomposite hydrogel

In this study, carboxymethyl cellulose based graft poly(acrylamide) hydrogel (CMC-g-P(AAm)) and its nanocomposite with montmorillonite (CMC-g-P(AAm)/MMT) were produced by the free radical method and it was used to malachite green (MG) dye removal from aqueous solution. The properties and characterization of the adsorbents were investigated using FTIR, SEM, TGA, and XRD analyzes, and the results showed that MMT nanoparticles were successfully distributed in the hydrogel system. MMT nanoparticles were loaded into the hydrogel system with different weight percentages and the maximum adsorption efficiency of MG dye was determined at 10 wt% MMT. Also, the effect of temperature, contact time, initial concentration of MG dye and initial pH on the adsorption efficiency of MG dye was studied in a batch. Equilibrium behavior investigation of the adsorption process showed that the equilibrium data determined are in good agreement with the Langmuir isotherm model and the monolayer surfaces play an effective role in the adsorption process. The maximum monolayer adsorption capacity (qmax) determined using the Langmuir isotherm model for CMC-g-P(AAm) and CMC-g-P(AAm)/MMT were determined to be 158.1 mg/g and 172.4 mg/g, respectively. Also, the kinetic study showed that the pseudo-second- order kinetic model is more capable of describing the kinetic behavior of the process than other models. Also, the α parameter values for the MG dye adsorption process using CMC-g-P(AAm) and CMC-g-P(AAm)/MMT were determined to be 0.6337 mg/g·min and 31.04 mg/g·min, respectively. This indicates that the produced composite has a high adsorption value. Gibbs free energy (ΔG°) was negative for the adsorption processes in the range of 25–50 °C, indicating that the process was spontaneous. In addition, the enthalpy parameter (ΔH°) was determined for the adsorption process using CMC-g-P(AAm) and CMC-g-P(AAm)/MMT nanocomposite hydrogels at 39.859 KJ/mol and 74.736 KJ/mol, respectively. Positive ΔH° indicates that the process is endothermic in the range of 25–50 °C using both adsorbents. Also, the concentrations effect of Na+ and K+ ions on adsorption efficiency was investigated and it was concluded that the efficiency of the adsorption process decreased with the increase of ions concentration. Adsorption efficiency decrease can be due to the occupation of active sites and repulsive electrostatic interactions at the adsorbent surface with the MG dye molecule.