Reactive Green Research Articles

Photocatalytic performance of TiO 2 impregnated polyester for the degradation of Reactive Green 12: Implications of the surface pretreatment and the microstructure

In the present work, we investigate the degradation of recalcitrant industrial textile dye (Reactive green 12) in aqueous solution by TiO2 impregnated polyester at room temperature. The TiO2 loading on polyester was optimized using different polyester pretreatments (plasma surface activation and UV-C photons). The applied surface pretreatments led to slightly different microstructure, crystalline sizes and photocatalytic activities. Both catalyst tests showed no photocatalytic activity for Radio-Frequency plasma (from now as “RF-plasma”) pretreated polyester under visible light and a lower activity compared to UVC-pretreated-impregnated-fabrics under UV light. This was attributed to the TiO2 aggregation on the surface of RF-plasma activated polyester. However, the photocatalytic performance of UV-C activated catalyst was investigated studying the optimal reaction conditions such as pollutant initial concentration, applied light (UV or Visible), catalyst loading and the presence of hydrogen peroxide at different concentrations. Under optimized operating conditions, namely catalyst dose of 5.18 g/L and an initial dye concentration of 2 mg/L, the removal of Reactive green 12 reached 100% under UV light and 87.14% under visible light within 120 min. Moreover, the presence of hydrogen peroxide showed a positive impact on the degradation, since the time needed for total dye decreased to 80 min under UV light irradiation for a [H2O2] to [RG 12]0 ratio in the range 20–30. The kinetic results showed that the removal of this recalcitrant dye nearly followed a Langmuir-Hinshelwood (L-H) model with a regression coefficient (R2) value of 0.926. The catalyst activity was found to be stable for more than five reuse cycles. © 2017 Elsevier B.V.

Removal of metal complexed azo dyes from aqueous solution using tris(2-aminoethyl)amine ligand modified magnetic p(GMA-EGDMA) cationic resin: Adsorption, isotherm and kinetic studies

This study demonstrates efficient removal of Reactive Green 5 (RG-5) and Reactive Brown 10 (RB-10) metal complexed dyes from aqueous solution using tris(2-aminoethyl)amine ligand (TAA) attached magnetic poly(glycidylmetharylate-ethyleneglycol dimethacrylate), Mp(GMA-EGDMA)-TAA, resin. The chemical structure and morphology of the magnetic resin were characterized by FTIR, XRD, SEM, VSM, BET, and analytical methods It was observed that the synthesized resin has ferromagnetic behavior under magnetic field which can permit for effective separation from adsorption medium. In the remaining study, the adsorption of RG-5 and RB-10 dyes from their aqueous solutions was realized with Mp(GMA-EGDMA)-TAA resin by varying of initial pH, resin dosage, initial dye concentration, temperature and salt concentration. The maximum adsorption capacity of the resin was found to be 238.7, and 162.4mg/g for RG-5 and RB-10 dyes, respectively. Kinetics and isotherm models, and adsorption thermodynamic were investigated to best describe the sorption process. The results accorded with the pseudo-second-order kinetic model. The Langmuir and Temkin isotherm models can describe the adsorption process appropriately. The thermodynamic parameters indicated that the sorption process was exothermic. In addition, adsorption/desorption studies were performed to evaluate the reusability of the Mp(GMA-EGDMA)-TAA resin, and more 94% of the adsorbed metal complexed dye can be desorbed from the magnetic resin. Repeated use test indicated that the synthesized magnetic resin had good reusability performance especially up to fifteen cycle. Finally, the Mp(GMA-EGDMA)-TAA resin proved to be a sustainable resin effective in low dosage and magnetically separable after laden with pollutant compounds. Thus, the synthesized resin could significantly reduce operation time, and could be applied for treatment of industrial effluents rich in inorganic and organic pollutants.

Effect of chelating agents on Reactive Green 19 decolorization through Fe0-activated persulfate oxidation process

The effect of chelating agents on the decolorization of Reactive Green 19 (RG19) through Fe0 activated persulfate (PS/Fe0) process was investigated. Though other previous studies reported that chelating agent can enhance the degradation of organic contaminant in Fenton-like system, our finding showed that the presence of chelating agents would chelate free Fe2+ and minimize free Fe2+ concentration, which resulted in the retardation of RG19 decolorization. RG19 decolorization decreased to 7%, 21%, and 15% in the presence of sodium citrate, sodium EDTA, and sodium oxalate, compared with control test (without chelating agent, 99%) within 10 min. The degradation efficiencies decreased with increasing chelating agent concentrations because of complex formation with Fe2+. Higher PS concentration, Fe0 dosage, and temperature had an obvious enhancement for RG19 decolorization efficiency. Elucidation of RG19 containing sodium EDTA degradation pathways indicated that PS/Fe0 process could degrade RG19 to carboxylic acids and inorganic salts efficiently. The presence of sodium EDTA had no influence on by-products, and EDTA just played a chelating agent function for chelating Fe ions.

Removal of textile dye reactive green-19 using bacterial consortium: Process optimization using response surface methodology and kinetics study

In the present work, removal of a textile dye Reactive Green-19 from the aqueous medium was investigated using a developed bacterial consortium. Optimal combinations of three significant process parameters pH (5–10); incubation temperature (25–45°C); and Yeast extract concentration (0–1.5g/100mL) were determined using response surface methodology. Experiments were based on Box–Behnken surface statistical design, performed at initial dye concentration of 100mg/L as a fixed input parameter. Regression analysis displayed good fit of the experimental data to the second-order polynomial model with the coefficient of determination (R2)=0.9974 and Predicted (R2)=0.9677. The adequacy of the model was established with various descriptive statistics like lack of fit, coefficient of variation, predicted residual sum of squares, and adequate precision. The optimal decolorization conditions were as follows: temperature, 32.04°C; pH, 8.3 and Yeast Extract concentration, 1.16g/100mL. Under optimized conditions, more than 97% removal efficiency was achieved within 24h. First order kinetic fitted well with experimental data for different concentrations of dye Reactive green-19. Michaelis-Menten kinetics was used to define the apparent relationship between the decolorization rate and the dye concentration at optimized condition. The double reciprocal plot for kinetics yield maximum decolorization rate, Vm=120.48h−1 and half saturation constant, Km=1674mg/L. Biodegradation of dye was confirmed through UV–vis spectroscopy, Fourier transform infra-red spectroscopy, and High-performance liquid chromatography analysis. Reactive green-19 degradation products were identified through GC–MS analysis.

Microbial fuel cell operation using monoazo and diazo dyes as terminal electron acceptor for simultaneous decolourisation and bioelectricity generation

Monoazo and diazo dyes [New coccine (NC), Acid orange 7 (AO7), Reactive red 120 (RR120) and Reactive green 19 (RG19)] were employed as electron acceptors in the abiotic cathode of microbial fuel cell. The electrons and protons generated from microbial organic oxidation at the anode which were utilized for electrochemical azo dye reduction at the cathodic chamber was successfully demonstrated. When NC was employed as the electron acceptor, the chemical oxygen demand (COD) removal and dye decolourisation efficiencies obtained at the anodic and cathodic chamber were 73±3% and 95.1±1.1%, respectively. This study demonstrated that the decolourisation rates of monoazo dyes were ∼50% higher than diazo dyes. The maximum power density in relation to NC decolourisation was 20.64mW/m2, corresponding to current density of 120.24mA/m2. The decolourisation rate and power output of different azo dyes were in the order of NC>AO7>RR120>RG19. The findings revealed that the structure of dye influenced the decolourisation and power performance of MFC. Azo dye with electron-withdrawing group at para substituent to azo bond would draw electrons from azo bond; hence the azo dye became more electrophilic and more favourable for dye reduction.

A highly efficient immobilized ZnO/Zn photoanode for degradation of azo dye Reactive Green 19 in a photocatalytic fuel cell

Photocatalytic fuel cell (PFC) is a potential wastewater treatment technology that can generate electricity from the conversion of chemical energy of organic pollutants. An immobilized ZnO/Zn fabricated by sonication and heat attachment method was applied as the photoanode and Pt/C plate was used as the cathode of the PFC in this study. Factors that affect the decolorization efficiency and electricity generation of the PFC such as different initial dye concentrations and pH were investigated. Results revealed that the degradation of Reactive Green 19 (RG19) was enhanced in a closed circuit PFC compared with that of a opened circuit PFC. Almost 100% decolorization could be achieved in 8 h when 250 mL of 30 mg L−1 of RG19 was treated in a PFC without any supporting electrolyte. The highest short circuit current of 0.0427 mA cm−2 and maximum power density of 0.0102 mW cm−2 was obtained by PFC using 30 mg L−1 of RG19. The correlation between dye degradation, conductivity and voltage output were also investigated and discussed.

Reactive Green 19 modified poly(HEMA) nanostructures for alcohol dehydrogenase immobilization

Reactive Green 19 modified poly(HEMA) nanostructures for alcohol dehydrogenase immobilization In this presented work, poly(HEMA) nanostructures were prepared by using surfactant free emulsion polymerization technique. Magnetic character was introduced to the polymer by simple adding of Fe 3 O 4 to the polymerization medium while polymerization taken place. These magnetic nanostructures were modified with Reactive Green 19 dye by nucleophilic substitution reaction. Synthesized dye attached poly(HEMA) nanostructures were characterized by FTIR, ESR, AFM and EDX analysis. These nanostructures were used for immobilization of alcohol dehydrogenase by the help of dye affinity interaction. Effects of medium pH and temperature, and substrate concentration on the activity of the alcohol dehydrogenase were investigated. Optimum pHs for free and immobilized alcohol dehydrogenase were found to be 8.0 (in phosphate buffer), while optimum temperature of both enzyme types was found to be 25 °C. Kinetic parameters of free and immobilized enzyme were also determined. Both K m ad V max values of the immobilized alcohol dehydrogenase were found to be higher than that of free enzyme. Also, thermal, operational and storage stability of immobilized enzyme were investigated and it was found that immobilized preparation showed more stability than free one. Immobilized preparation worked 10 successive reuse with a little decrease in its activity.

Reversible papain immobilization onto poly(AAm–MMA)-based cryogels

In the present work, new dye ligand affinity chromatographic support for papain adsorption was synthesized. For this purpose, poly(acrylamide–methyl methacrylate) [poly(AAm–MMA)] cryogels were synthesized by using the free radical cryopolymerization technique. These cryogels were then functionalized with Reactive Green 19 dye and were characterized with Fourier transform infrared, environmental scanning electron microscopy, macroporosity and energy-dispersive X-ray spectrometer analyses. Incorporation of the dye molecule onto cryogel structure was clearly demonstrated by these characterization techniques and pore diameter of the cryogel was found to be around 30–40μm. Effects of medium pH, initial papain concentration, medium temperature and ionic strength on the papain adsorption onto dye-attached cryogel were also investigated. Maximum papain adsorption was found to be 40.66 mg g−1 cryogel by using pH 5.5 acetate buffer at 25°C. Reusability profile of the cryogel was also investigated and it was found that the adsorption capacity of the cryogel decreased only about 2.13% at the end of the 10 reuses. Activity studies of papain in desorption medium were carried out and it was found that desorbed papain was active and showed 88.5% of its initial activity.

Enhanced electricity generation and degradation of the azo dye Reactive Green 19 in a photocatalytic fuel cell using ZnO/Zn as the photoanode

The photocatalytic fuel cell is under consideration as a potential alternative system for recovering energy from the photocatalytic degradation of organic pollutants. In this study, a single-chambered photocatalytic fuel cell using ZnO/Zn as the photoanode and platinum loaded carbon as the cathode was constructed, and Reactive Green 19 was used as the organic pollutant. Operating parameters such as aeration, organic pollutant and photoanode were evaluated. Electricity generation and degradation efficiency were investigated in the presence of different supporting electrolytes such as sodium chloride, sodium sulfate and magnesium sulfate. The results indicated that the addition of sodium sulfate as the supporting electrolyte afforded the highest short circuit current: 2.64 mA cm−2 and a maximum power density of 1.2696 mW cm−2. However, in terms of photocatalytic degradation, the presence of sodium chloride as the supporting electrolyte led to the highest dye degradation efficiency. In addition to electrolytes, the voltage output and degradation rate were significantly affected by different initial concentrations of dye. Ultraviolet–Visible spectroscopy and chemical oxygen demand analysis determined that 100% decolorization and 92% mineralization of 10 mg L−1 of dye could be achieved after 8 h using sodium chloride as the supporting electrolyte in an aerated photocatalytic fuel cell.

Adsorption of reactive green 19 from water using polyaniline/bentonite

Polyaniline/bentonite was used in this study to investigate its adsorption behaviors of reactive green 19. Influencing factors including contact time, pH, temperature and inorganic salts were investigated. The adsorption kinetic data fitted the pseudo-second-order model better than the pseudo-first-order and Elovich models, and the Langmuir model was better than the Freundlich model to describe the adsorption process. Thermodynamic studies indicated that the adsorption of reactive green 19 by polyaniline/bentonite was an endothermic and spontaneous process. Experimental data indicated that both NaCl and Na2SO4 could improve the reactive green 19 adsorption as a result of aggregation of the dye molecules in solution induced by the inorganic salts, and an increase of pH value from 5 to 9 caused a slight decrease in reactive green 19 adsorption.

Interactive influences of decolorized metabolites on electron-transfer characteristics of microbial fuel cells

This study clearly uncovered how and why decolorized metabolites (DM) or intermediates could stimulate bioelectricity-generating capabilities in microbial fuel cells (MFCs) due to synergistic interactions. It also disclosed mysteries behind the reversible stabilities of electron shuttles (ESs) of such biodegraded intermediates in practical MFCs. Electrochemical impedance spectra indicated that DM of reactive green 19 (RG19), reactive blue 160 (RBu160) and malachite green (MG) could significantly stimulate bioelectricity-generating capabilities in MFCs due to significant reduction of internal resistance. With autocatalysis of DM, apparently feedback stimulation of decontaminated species directly controlled the performance of MFC-based bioremediation.

Catalytic Activity of Iron Doped Hexagonal Mesoporous Silica (Fe-HMS) for Degradation of Reactive Green-19 Dye in Water

Iron nitrate supported hexagonal mesoporous (Fe-HMS) catalyst were successfully synthesized for Fenton-like oxidative degradation of Reactive Green-19 (RG19). Effects of pH, light intensity, catalyst amount, dye concentration, sensitizers, etc., were studied to optimize conditions for enhanced photo-catalytic activity. SEM, EDX, BET and UV–Vis (diffused reflectance mode) techniques were used to revealed the Fe-HMS physico-chemical properties. Kinetic study RG-19 treatment process at a reaction temperature 40°C, pH 3, 3 mgL-1 of Fe-HMS, 50 μL of H2O2, and 100 mgL-1 of dye were successfully carried out. The Fenton-like process correlation coefficient favors the first order kinetic model. COD and metal leaching analysis were done and results revealed that they were below DOE standard for effluent. Therefore, the treated water can safely discharge to the environment. The Fe-HMS catalyst reusability proved that it could be reused and has stability in reaction more than four cycles.

GA 처리 후 급 성장하는 완두콩(Pisum sativum L.) 발아체로부터 분리된 중성 invertase의 특성

Invertase (β-D-fructosfuranosidase, EC 3.2.1.26) catalyzes the hydrolysis of sucrose into D-glucose and D-fructose. Three biochemical subgroups of invertases have been investigated in plants: vacuolar (soluble acid), cytoplasmic (soluble alkaline), and cell wall-bound (insoluble acid) invertases. An isoform of neutral invertase was purified from pea seedlings (Pisum sativum L.) and treated with gibberellic acid (GA) by sequential procedures consisting of ammonium sulfate precipitation, ion-exchange chromatography, absorption chromatography, and reactive green-19 affinity chromatography. The results of the overall insoluble invertase purification were a 430-fold increase. The purified neutral invertase was not glycosylated and had an optimum pH between neutral and alkaline (pH 6.8-7.5). It was inhibited by Tris, as well as by heavy metals, such as Hg 2+ and Cu 2+ . Typical Michaelis?Menten kinetics were observed when the activity of the purified invertase was measured, with sucrose concentrations up to 100 mM. The K m and V max values were 12.95 mM and 2.98 U/min, respectively. The molecular mass was around 20 kDa. The sucrose-cleaving enzyme activity of this enzyme is similar to that of sucrose synthase and fructosyltransferase, but its biochemical characteristics are different from those of sucrose synthase and fructosyltransferase. Based on this biochemical characterization and existing knowledge, neutral INV is an invertase isoform in plants.

Preparation and characterization of graphene oxide/TiO2 blended PES nanofiltration membrane with improved antifouling and separation performance

Polyethersulfone (PES)-based mixed matrix nanofiltration membrane was developed by blending with partially reduced graphene oxide (rGO)/TiO2 nanocomposite. The effect of rGO/TiO2 contents on the morphology and performance of the prepared membranes was investigated by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), atomic force microscopy (AFM) and water contact angle analysis. The blended membranes displayed improved water permeability and fouling resistance compared to the bare PES. When the content of rGO/TiO2 was 0.15wt.%, the water flux reached a maximum value (45.0kg/m2h) nearly twice of that of the bare PES membrane (23.1kg/m2h). Fouling resistance of the membranes studied by bovine serum albumin (BSA) solution filtration showed that 0.1wt.% rGO/TiO2 membrane had the best antifouling property. Nanofiltration performance of the prepared membranes was evaluated by rejection of three organic dyes with different molecular weights (i.e. C. I. Reactive Green 19, C. I. Direct Yellow 12 and C. I. Reactive Blue 21). The rGO/TiO2/PES membranes showed better dye removal performance than the bare PES. Compared with TiO2/PES and GO/PES membranes, rGO/TiO2/PES membranes presented the best water permeation rate, antifouling ability and dye rejection.

Comparison between the photocatalytic degradation of single and binary azo dyes in TiO2 suspensions under solar light irradiation

Textile industries discharge a large quantity of colored wastewater which is harmful to the ecosystem. In this study, two kinds of dyes were investigated: the mono azo Acid Orange 7 (AO7) and diazo Reactive Green 19 (RG19). The photocatalytic degradation of single (AO7, RG19) azo dye and binary (AO7 and RG19 mixture) azo dye aqueous solutions was photocatalyzed by commercial titanium dioxide (TiO2, P25) under solar light irradiation. The objectives of this study are to compare the photocatalytic degradation between single and binary azo dye aqueous solution and to study the various parameters such as the effect of different initial azo dye concentrations, different initial azo dye pH values, and compare the adsorption capacity of azo dyes with and without solar light irradiation, which influences the photocatalytic activities of single and binary azo dye aqueous solutions in a TiO2 suspension. The results showed that photocatalytic degradation of AO7 and RG19 in a single azo dye aqueous solution was faster than a binary azo dye solution under the solar light irradiation process. Chemical oxygen demand results revealed that complete mineralization could be achieved for both AO7 and RG19 azo dyes under solar light irradiation within 22 hours.

Short Time Exposure (STE) test in conjunction with Bovine Corneal Opacity and Permeability (BCOP) assay including histopathology to evaluate correspondence with the Globally Harmonized System (GHS) eye irritation classification of textile dyes

Eye irritation evaluation is mandatory for predicting health risks in consumers exposed to textile dyes. The two dyes, Reactive Orange 16 (RO16) and Reactive Green 19 (RG19) are classified as Category 2A (irritating to eyes) based on the UN Globally Harmonized System for classification (UN GHS), according to the Draize test. On the other hand, animal welfare considerations and the enforcement of a new regulation in the EU are drawing much attention in reducing or replacing animal experiments with alternative methods. This study evaluated the eye irritation of the two dyes RO16 and RG19 by combining the Short Time Exposure (STE) and the Bovine Corneal Opacity and Permeability (BCOP) assays and then comparing them with in vivo data from the GHS classification. The STE test (first level screening) categorized both dyes as GHS Category 1 (severe irritant). In the BCOP, dye RG19 was also classified as GHS Category 1 while dye RO16 was classified as GHS no prediction can be made. Both dyes caused damage to the corneal tissue as confirmed by histopathological analysis. Our findings demonstrated that the STE test did not contribute to arriving at a better conclusion about the eye irritation potential of the dyes when used in conjunction with the BCOP test. Adding the histopathology to the BCOP test could be an appropriate tool for a more meaningful prediction of the eye irritation potential of dyes.

Removal of Reactive Green 19 dye from synthetic wastewater using electrocoagulation and aluminum electrodes

Textile dyeing is considered to be one of the major industrial sources of high rates of organic and aromatic compounds. Conversely, these compounds have become a significant environmental problem. Many methods have been investigated for color removal from dye-containing wastewater. In this research, the efficiency of the electrocoagulation (EC) process with aluminum electrodes in the removal of Reactive Green 19 (RG-19) dye from synthetic solutions was studied. The experiments were conducted in a batch reactor equipped with 4 aluminum electrodes with a volume of 2 l. Dye concentrations were measured (λ max = 630 nm). The effects of operating parameters, such as voltage, reaction time, initial dye concentration, energy consumption, pH, KCl concentration, and inter-electrode distance, on removal efficiency were investigated. The highest removal efficiency of RG-19 was found to be 33.49, 60.32, 72.43, 93.63, and 94.91 percent for initial voltage of 10, 20, 30, 40 and 50 v, respectively, in optimum conditions (pH = 11, KCL concentration = 0.005 M, and distance = 1 cm). The removal was effectively reduced to less than 99.88% when the initial dye concentration increased from 25 to 150 mg/l. In addition, by increasing KCl concentration and decreasing electrode distance, removal efficiency increased considerably. Based on the results, EC process by aluminum electrodes is an efficient and suitable method for reactive dye removal from wastewater.

Development of bioreactor systems for decolorization of Reactive Green 19 using white rot fungus

The ability of Trametes versicolor U97 to decolorize Reactive Green 19 in bioreactor was investigated to determine whether the immobilized enzyme would be suitable for decolorization of Reactive Green 19 under agitation and nonagitation condition. Free cells of T. versicolor U97 showed an ability to decolorize Reactive Green 19 by approximately 44% in 72 h. Mediator mixture containing Tween 80, MnSO4–H2O2, and hydroxybenzotriazole was added to the immobilized fungi to improve the decolorization process. Reactive Green 19 was decolorized by the immobilized fungi by approximately 80%, which is a twofold improvement over decolorization without mediators. In bioreactor system, decolorization of Reactive Green 19 was increased to 82% after 72 h. We evaluated the efficiency of the decolorization model for use in a small industry. Our results indicated that the wastewater discharge of 10 m3 d−1 requires a reactor volume of 24 m3 to obtain 80% decolorization with a retention time of 1.75 d. This study identifed that bioreactor of T. versicolor U97 immobilization is the most promising method for use in decolorize Reactive Green 19 and may be suitable for the treatment of wastewater in small industries.

Modeling and optimization of Reactive Green 19 oxidation on a BDD thin-film electrode

A membrane-free electrochemical reactor with a boron-doped diamond (BDD) anode was used to degrade Reactive Green 19 (RG19), an azo dye widely used in the textile industry. Oxidation experiments were carried out under galvanostatic conditions according to a central composite design. The factors investigated were current density (100–500 A/m2), pH (3–11), chloride concentration (0–0.5 M) and agitation rate (250–750 rpm), while the response variables were the efficiencies of color and TOC removal. Color removal was strongly affected by chloride concentration and, to a lesser extent, by current density and stirring rate. In contrast, current density was the factor with the greatest influence on TOC removal, followed by pH and chloride concentration. Under optimal degradation conditions, the efficiencies of color and TOC removal reached values close to 90% and 80%, respectively. Taken together, the results of this study suggest that the anodic oxidation of RG19 on a BDD thin-film electrode can be a suitable method to degrade this dye, once the optimum operating conditions have been established.

Dye functionalized cryogel columns for reversible lysozyme adsorption

In this study, poly (methyl methacrylate–glycidyl methacrylate) [poly(MMA-GMA)] cryogels were prepared by radical cryocopolymerization of MMA with GMA as a functional comonomer. Reactive Green 19 dye was then attached to the cryogel by nucleophilic substitution reaction, and this dye-attached cryogel column was used for lysozyme adsorption. Characterization of the cryogel was performed by Fourier transform infrared spectroscopy, environmental scanning electron microscopy, Brunauer–Emmett–Teller, and energy dispersive X-ray analysis. Pore size of the cryogels was 15–30 μm and pores were interconnected structure. Attached amount of Reactive Green 19 to cryogel support was calculated as 106.25 μmol/g cryogel. Lysozyme adsorption studies were carried out by using a continuous system. It was found that the maximum amount of lysozyme adsorption (32 mg/g cryogel) obtained from experimental results was found to be approximately same with the calculated Langmuir adsorption capacity (33 mg/g cryogel). Desorption of adsorbed lysozyme was carried out by using 1.5 M NaCl in pH 4.5 acetate buffer, and desorption yield was found to be 97.4%. Cryogels were very stable, and it was found that there was no remarkable reduction in the adsorption capacity at the end of ten adsorption–desorption cycles. As a result, Reactive Green 19-attached cryogels have great advantages such as easy preparation, rapid adsorption, and desorption, being economic and allowing the direct separation of proteins.