Hydrogel‐Assisted Transfer of Graphene Oxides into Nonpolar Organic Media for Oil Decontamination

In this work, graphene oxide (GO)‐loaded agarose hydrogel was transferred into oil such as hexadecane via stepwise solvent exchange with no chemical modification of the GO hydrophilic surface and the agarose network. After transfer, the GOs, loaded in the agarose network, could effectively and efficiently adsorb lipophilic dyes in oil via hydrogen bonding between the polar groups of the GOs and the dyes. The maximum adsorption capacity was 355.9 mg g^?1 for Nile red for instance, which is substantially larger than that of pristine agarose hydrogel and hydrophilic GO powder. The dye concentration for effective adsorption can be as low as 0.5 ppm. Thus, the present work demonstrates the promising potential of using hydrophilic adsorbents for efficient removal of polar impurities from oil.     

Dye removal by a novel hydrogel‐clay nanocomposite with enhanced swelling properties

Acrylamide (AAm)‐2‐acrylamide‐2‐methylpropanesulfonic acid sodium salt (AMPSNa) hydrogel and AAm‐AMPSNa/clay hydrogel nanocomposite having 10 w% clay was prepared by in situ copolymerization in aqueous solution in the presence of a crosslinking agent (N,N′‐methylenebisacrylamide (NMBA)). Swelling properties and kinetics of the hydrogel samples were investigated in water and aqueous solutions of the Safranine‐T (ST) and Brilliant Cresyl Blue (BCB) dyes. The swelling and diffusion parameters were also calculated in water and dye solutions. It was observed that the AAm‐AMPSNa/clay hydrogel nanocomposite exhibits improved swelling capacity compared with the AAm‐AMPSNa hydrogel. It was also found that the diffusion mechanisms show non‐Fickian character. Adsorption properties of the hydrogel samples in the aqueous solution of ST and BCB dyes were also investigated. Clay incorporation into the hydrogel structure increased not only the adsorption capacity but also the adsorption rate. Adsorption capacity values of the hydrogel nanocomposite were found to be 484.2 and 494.2 mg g^?1 for the ST and BCB dyes, respectively. It was seen that the adsorption of dyes by the hydrogel nanocomposite completed in 10 min while the AAm‐AMPSNa hydrogel adsorbed dyes approximately in 90 min. Adsorption data of the samples were modelled by the pseudo‐first‐order and pseudo‐second‐order kinetic equations in order to investigate dye adsorption mechanism. It was found that the adsorption kinetics of hydrogel nanocomposite followed a pseudo‐second‐order model. Equilibrium isotherms were analyzed using the Langmuir and Freundlich isotherms. It was seen that the Langmuir model fits the adsorption data better than the Freundlich model. Copyright © 2008 John Wiley & Sons, Ltd.     

Adsorptive features of polyacrylic acid hydrogel for UO2 2+

Polyacrylic acid hydrogel was synthesized by Free Radical polymerization and characterized by means of FTIR. The FTIR results show that the carboxylic groups in the complexes coordinated to the metal ions in the form of two dentate. The effects of contact time, solid/liquid ratio, pH value, and initial concentration on the adsorption of UO₂ ²⁺ ions onto polyacrylic acid were investigated. The adsorption of UO₂ ²⁺ ions was highly dependent on the initial pH of metal ions solution and initial metal ions concentration. The adsorption kinetic data indicated that the chemical adsorption was the swiftness processes, the adsorption equilibrium could be achieved within 15 min. And there are very good correlation coefficients of linearized equations for Freundlich model, which indicated that the sorption isotherm of the hydrogel for UO₂ ²⁺ can be fitted to the Freundlich model. It was found that the maximum adsorption quantity of UO₂ ²⁺ was 1,179 mg/g. After five times of repeated tests for the hydrogel it still remained its excellent adsorption.     

Heavy metal ions removal by nano-sized spherical polymer brushes

Nano-sized spherical polymer brushes(SPBs) consisting of both a polystyrene(PS) core and a brush shell of poly(acrylic acid)(PAA), poly(N-acrylcysteamine)(PSH), or poly(N-acrylcysteamine-co-acrylic acid)(P(SH-co-AA)), were prepared by photo-emulsion polymerization. The core-shell structure was observed by dynamic light scattering and transmission electron microscopy. Due to the strengthened Donnan effect, the PAA brush can adsorb heavy metal ions. Effects of the contact time, thickness of PAA brush and pH value on the adsorption results were investigated. Due to the coordination between the mercapto groups and heavy metal ions as well as the electrostatic interactions, SPBs with mercapto groups are capable to remove heavy metal ions selectively from aqueous solutions. The order of adsorption capacity of the heavy metal ions by SPBs with mercapto groups is: Hg2+ ≈ Au3+ Pb2+ Cu2+ Ni2+. The adsorbed heavy metal ions can be eluted from SPB by aqueous HCl solution, and the SPBs can be recovered. After three regenerations the recovered SPBs still maintain their adsorption capacity.     

Photocatalytic degradation of triazine dyes over N-doped TiO2 in solar radiation

Photocatalytic degradation of the reactive triazine dyes Reactive Yellow 84 (RY 84), Reactive Red 120 (RR 120), and Reactive Blue 160 (RB 160) on anatase phase N-doped TiO₂ in the presence of natural sunlight has been carried out in this work. The effect of experimental parameters like initial pH and concentration of dye solution and dosage of the catalyst on photocatalytic degradation have also been investigated. Adsorption of dyes on N-doped TiO₂ was studied prior to photocatalytic studies. The studies show that the adsorption of dyes on N-doped TiO₂ was high at pH 3 and follows the Langmuir adsorption isotherm. The Langmuir monolayer adsorption capacity of dyes on N-doped TiO₂ was 39.5, 86.0, and 96.3 mg g^?1 for RY 84, RR 120, and RB 160, respectively. The photocatalytic degradation of the dyes follows pseudo first-order kinetics and the rate constant values are higher for N-doped TiO₂ when compared with that of undoped TiO₂. Moreover, the degradation of RY 84 on N-doped TiO₂ in sunlight was faster than the commercial Aeroxide^® P25. However, the P25 has shown higher photocatalytic activity for the other two dyes, RR 120 and RB 160. The COD of 50 mg l^?1 Reactive Yellow-84, RR 120 and RB 160 was reduced by 65.1, 73.1, and 69.6 %, respectively, upon irradiation of sunlight for 3 h in the presence of N-doped TiO₂. The photocatalyst shows low activity for the degradation of RY 84 dye, when its concentration was above 50 mg l^?1, due to the strong absorption of photons in the wavelength range 200–400 nm by the dye solution. LC–MS analysis shows the presence of some triazine compounds and formimidamide derivatives in the dye solutions after 3 h solar light irradiation in the presence of N-doped TiO₂.     

A new fast swelling poly[DAPB-co-DMAAm-co-AASS] superabsorbent hydrogel for removal of anionic dyes from water

The objective of this research is to utilize a new poly[N,N-diallyl pyrrolidinium bromide-co-N,Ndimethyl acrylamide-co-acrylic acid sodium salt]superabsorbent hydrogel（SAH）for the removal of two anionic dyes,e.g.,Reactive Red 5B（RR5B）and Reactive Orange M2R（ROM2R）,from water.The SAH was characterized by swelling in water,FTIR,TGA and SEM.The SAH DDA6showed good swelling property and thermal stability.We have also investigated the parameters affecting dye adsorption such as pH,adsorbent dose,adsorption rate and initial dye concentration.The experimental data were also analyzed by applying the well known Langmuir and Freundlich isotherm models.     

Ultrasonic-enhanced synthesis of rubber-based hydrogel for waste water treatment: Kinetic,isotherm and reusability studies

Hydrogel is used as an adsorbent for the removal of dyes and heavy metals in waste water. In this work, different methods of synthesising novel hydrogels from liquid natural rubber (LNR) were investigated. The two different methods were ultrasonic-assisted polymerisation and heating under reflux. Through graft modification, LNR had initially combined with maleic anhydride (MaH) using benzoyl peroxide (BPO) as a radical initiator. After grafting, acrylic acid (AA) was crosslinked onto LNR-g-MaH using N,N-methylenebisacrylamide (MBA) and potassium persulfate (KPS) as a crosslinker and initiator, respectively. The best method between the two different techniques was identified via a five-level-two-factor response surface methodology (RSM). Higher adsorption percentage (93.34%) was observed in the ultrasonic technique. Meanwhile, the effects of adsorbent mass, dye concentration, pH solution and ionic strength were also investigated and results showed that different conditions were found to give different MG dye adsorption rates. The adsorption of MG dyes on hydrogel is dependent on pH and ionic strength solution. This action indicates an ion exchange mechanism. From an isotherm study, it was found that the Freundlich isotherm best fitted the adsorption of MG dyes. Furthermore, the adsorption kinetic data followed the pseudo-second order kinetic model and the reusability of hydrogel was also investigated.     

An enhanced immobilization of BSA biomolecule on anionic hydrogels: swelling and adsorption modeling

The three-dimensional structure of hydrogels plays a leading role in several areas of applications. The hydrogels are more and more used as systems of immobilized and controlled release of biomolecules in biotechnology and bio-pharmacy industries. To improve protein adsorption capacity in poly(acrylamide) hydrogels, maleic acid co-monomer was included into the reaction mixture during hydrogel synthesis. So, hydrogels of poly(acrylamide) and its copolymers with diprotic maleic acid were prepared by copolymerization and chemical crosslinking with N,N′-methylene bis-acrylamide. Swelling behavior in distilled water, in physiological saline and in bovine serum albumin (BSA) solutions was studied. Influence of initial BSA concentration on hydrogel swelling and BSA adsorption was investigated. The high amount of maleic acid present in the hydrogels has a significant effect on the swelling behavior and BSA adsorption. Results showed that the pH sensitivity of hydrogels resulted in the high amount of adsorbed BSA. The adsorption isotherms were described by Langmuir and Freundlich models. The thermodynamic parameter (ΔG _ads ⁰ ) was determined for all obtained hydrogels. We demonstrated the favorable character and reversibility of the BSA adsorption process.     

Chemical recycling of PET waste into hydrophobic textile dyestuffs

The paper aims at effective chemical recycling of poly(ethylene terephthalate) (PET) fiber waste into useful products, such as hydrophobic disperse dyes for synthetic textiles. For this, PET fiber waste was glycolytically depolymerized using excess of ethylene glycol in the presence of sodium sulfate as catalyst. The product, pure bis(2-hydroxyethylene terephthalate) (BHET) was obtained with >60% yield by successive recrystallization. In order to synthesize hydrophobic disperse dyes, applicable to synthetic textile fibers, BHET was converted to bis(2-chloroethylene terephthalate), reacted with the p-nitro benzoic acid, reduced and then reacted with bromine and potassium thiocyanate to get benzothiazole derivative. Coupling with N,N-diethylaniline produced a bright yellow disperse dye (Dye A). Similarly, coupling of p-amino benzoic ester with N,N-diethylaniline led to an orange colored disperse dye (Dye B). These dyes were applied onto polyester fabric by conventional method. Results in terms of depth of dyeing, evenness and the performance characteristics were found to be promising.     

Preparation of thermosensitive,calix[4]arene incorporated P(NIPAM‐co‐HBCalix) hydrogel as a reusable adsorbent of nickel(II) ions

A calix‐conjugated thermo‐responsive hydrogel containing 15% tetra(5‐hexenyloxy)‐p‐tert‐butylcalix[4]arene (HBCalix), P(NIPAM‐co‐HBCalix), was used to remove nickel(II) ions from water. Both thermo‐sensitive properties and the Ni²⁺‐adsorption capabilities of the prepared P(NIPAM‐co‐HBCalix) hydrogels are investigated. Introduction of the monomer HBCalix considerably enhanced the adsorption of Ni²⁺ onto the hydrogel by chelation between hexenyloxy groups and metal ion. When HBCalix units capture Ni²⁺ and forms HBCalix/Ni²⁺ host–guest complexes, the lower critical solution temperature of the hydrogel shifts to a higher temperature due to both the repulsion between charged HBCali/Ni²⁺ groups and the osmotic pressure within the hydrogel. Adsorption studies were carried out by varying contact time, counter ion and initial concentration of Ni²⁺. The evaluation of adsorption properties showed that the hydrogel exhibited better correlation with Langmuir isotherm model. P(NIPAM‐co‐HBCalix) could be used repeatedly with little loss in adsorption capacity by simply changing the environmental temperature. This kind of ion‐recognition hydrogel is promising as a novel adsorption material for adsorption and separation of Ni²⁺ ions. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2401–2408     

Adsorption of xanthene food additive dyes to cellulose granules

It was found that three kinds of the synthetic food additive dyes, red nr. 3 (erythrosine), nr. 104 (phloxine), and nr. 105 (rose bengal) were adsorbed to the surface of charred cellulose granules and the maximum amounts of adsorption of these dyes were 3.75, 3.42, and 4.74 mg/g cellulose, respectively. Scanning electron microscopy-electron probe micro analysis (SEM-EPMA) showed a coating of the dyes on the surface of charred cellulose granules. Electron spectroscopy for chemical analysis (ESCA) suggested the presence of NH₃ ⁺ in the surface of charred cellulose granules. Since all three dye compounds have both anionic carboxylate and hydrophobic groups and were released from the surface of charred cellulose granules by 0.1 N NaOH solution, it was surmised that these three food additive dyes were bound to the surface of cellulose granules by both ionic and physical interactions.     

Swelling Behavior and Metal-Ion Uptake Capacity of pH-Responsive Hydrogels of Poly(N-acryloyl-N′-ethylpiperazine)

New hydrogels based on N-acryloyl-N′-ethylpiperazine (AcrNEP) and N,N-methylene bisacrylamide (MBA) were prepared by thermal initiated solution polymerization. The hydrogels swelled extensively in buffer solutions of low pH due to protonation of the amine functions of the monomers, while the swelling was less significant in buffer solutions of high pH. The increased swelling of the gel in low pH is due to the development and interaction of fixed charges within the gel network. As a result of the electrostatic repulsion between the charges the elastic constraint of the gel is modified which leads to pronounced swelling and hence to high water uptake. Water transport in the hydrogel both in buffer solutions of pH 2.6 and pH 8.4 was non-Fickian due to polymer relaxation (anomalous process). The gels demonstrated good uptake of divalent metal ions such as Ni²⁺, Co²⁺, and Zn²⁺, with high selectivity for Ni²⁺ ions due to the formation of a more stable ligand-metal complex. The metal uptake capacity increased with increase in pH of the solution, while an increase in the crosslinker amount of the hydrogel reduced its metal uptake capacity. In the presence of metal ions the swelling of the hydrogel reduced considerably due to the formation of additional physical crosslinks within the hydrogel network. The metal ion loaded hydrogels could be stripped and regenerated with 1 M sulfuric acid without any loss in swelling or metal uptake capacities.     

Removal of cationic dyes by poly(acrylamide-co-acrylic acid) hydrogels in aqueous solutions

Poly(acrylamide-co-acrylic acid (poly(AAm-co-AAc)) hydrogels prepared by irradiating with γ-radiation were used in experiments on swelling, diffusion, and uptake of some cationic dyes such as Safranine-O (SO) and Magenta (M). Poly(AAm-co-AAc) hydrogels irradiated at 8.0 kGy have been used for swelling and diffusion studies in water and cationic dye solutions. The maximum swellings in water, and SO, and M solutions observed are 2700%, 3500%, and 4000%, respectively. Diffusions of water and cationic dyes within hydrogels have been found to be non-Fickian in character. Adsorption of the cationic dyes onto poly(AAm-co-AAc) hydrogels is studied by the batch adsorption technique. The adsorption type was found Langmuir type in the Giles classification system. The moles of adsorbed dye for SO and M per repeating unit in hydrogel (binding ratio, r) have been calculated as 3834×10⁻⁶ and 1323×10⁻⁶, respectively. These results show that poly(AAm-co-AAc) hydrogels can be used as adsorbent for water pollutants such as cationic dyes.     

Adsorptive scavenging of cationic dyes from aquatic phase by H3PO4 activated Indian jujube (Ziziphus mauritiana) seeds based activated carbon: Isotherm,kinetics, and thermodynamic study

In the present work, a cost-effective Indian jujube seeds derived activated carbon (IJSAC) prepared via o-phosphoric acid chemical activation, is studied for the sequestration of acriflavine (AF) and Victoria blue B (VB) from the aquatic environment. The activated carbon is characterized by Fourier transform infrared spectroscopy, N₂-adsorption/desorption isotherm, scanning electron microscopy techniques and point of zero-charge measurement. The specific surface area (S_BET) of 571 m²/g with a pore radius of 22.45 Å specifies mesoporous nature of the IJSAC. The implication of operational conditions on the adsorption of both dyes onto IJSAC assessed by batch methodology, establish the optimal conditions as dosage (1.5 and 2.5 g/L), contact time (60 min), pH (8 and 10), and initial concentration (130 and 140 mg/L) for AF and VB uptake, respectively. The Freundlich adsorption isotherm model (R² = 0.99) appropriates the equilibrium data suggesting multilayer adsorption onto heterogeneous surface sites, while pseudo-second order (R² = 0.95–0.99) is the best fit kinetic model. The liquid film and intraparticle diffusion modelling demonstrate that the adsorption process of these dyes is governed by both the steps. Maximum Langmuir adsorption capacity is 113.6 mg/g for acriflavine and 92.78 mg/g for Victoria blue B. Thermodynamic studies indicate endothermic and spontaneous adsorption of dyes. The adsorption mechanism for the uptake of AF and VB by IJSAC most probably involves hydrogen bonding, electrostatic and π-π interactions. Based on its high adsorption capacity, relatively faster kinetics, and reusability, IJSAC can be perceived as a proficient and effective adsorbent for cationic dyes removal from the liquid waste.     

Experimental and theoretical studies of acridine orange as corrosion inhibitor for copper protection in acidic media

The corrosion process commonly limits the use of copper in practical applications. The use of corrosion inhibitors is one of the effective methods to reduce the corrosion rate of copper. In this research, the inhibition effect of acridine orange (3,6-bis(dimethylamine)acridine) (AcO) for the protection of copper in 0.5 ?M ?H₂SO₄ solution was studied. For this aim, the change of open circuit potential with exposure time (E_ocp-t), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR), anodic and cathodic potentiodynamic polarization measurements (PP) and chronoamperometry (CA) techniques were used. Some quantum chemical parameters (E_HOMO, E_LUMO and dipole moment) were calculated and discussed. The AcO film formed over the copper surface was examined by SEM, EDX, AFM and contact angle measurements. The electrochemical data showed that AcO is an effective corrosion inhibitor even at low concentrations (ranging between 99.1% and %99.4 ?at concentrations from 0.01 ?mM to 1 ?mM). The corrosion rate of copper decreases in the presence of the inhibitor by reducing both anodic and cathodic rates, which is depended on its concentration. This compound behaves as mixed-type corrosion inhibitors with predominantly cathodic type. Its adsorption on the copper surface obeys Langmuir adsorption isotherm. The value of adsorption equilibrium constant (K_ads) and the standard free energy of adsorption were ΔG_ads 1.298 x 10³ ?M^?1 and -27.71 ?kJ/mol in the case of 0.5 ?M ?H₂SO₄ solution containing 1.0 ?mM AcO, which shows the adsorption is high and spontaneous. The adsorbed inhibitor film over the metal increase contact angle of the surface, which suggests the more hydrophobic properties of the surface are increasing coming from the orientation of hydrophobic sites to the electrolyte. The zero charge potential (E_pzc) studies showed that the surface charge of the metal is positive in the corrosive media containing the inhibitor. Quantum chemical calculations showed that the binding of inhibitor molecules to the metal surface takes place through N atoms of the inhibitor.     

Combining mesoporous silica–magnetite and thermally-sensitive polymers for applications in hyperthermia

In this work, the synthesis strategy of a multifunctional system of [SBA-16/P(N-iPAAm)/Fe₃O₄] hybrids of interest for magneto-hyperthermia was explored. Magnetite nanoparticles coated by mesoporous silica were prepared by an alternative chemical route using neutral surfactant and without the application of any functionalization method. Monomer adsorption followed by in situ polymerization initiated by a radical was used to incorporate the hydrogel into the pore channels of the silica nanocomposite. Structural and magnetic characterization of the obtained materials was carried out by using thermal analysis, X-ray diffraction, N₂ adsorption desorption isotherms, ⁵⁷Fe Mössbauer spectroscopy, vibrating sample magnetometry and transmission electron microscopy. Measurements of alternating current magnetic-field-induced heating behaviour under different applied magnetic fields showed that the [SBA-16/P(N-iPAAm)/Fe₃O₄] hybrid here synthesized is suitable as a hyperthermia agent for biological applications.     

氧化石墨：制备及去除阳离子染料的性能

以石墨粉为原料按Hummers氧化法制备氧化石墨,借助X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、傅里叶变换红外光谱法(FTIR)和低温氮吸附-脱附对氧化石墨的结构和形貌进行了表征。结果表明,氧化石墨是不平整的、具有一定层状结构的褶皱片状,在其表面存在着许多含氧的官能团如:环氧基、羟基、羧基。此外还研究了氧化石墨对阳离子染料的吸附性能,结果表明:吸附过程的等温模型符合Langmuir等温式,对甲基紫、甲基绿、中性红这3种阳离子染料的最大饱和吸附量分别为:741,446和368 mg.g-1;对阳离子染料的吸附过程符合二级动力学方程。氧化石墨作为一种吸附剂能有效的去除阳离子染料与其较高的比表面积和与阳离子染料的静电吸引有关。     

Adsorption of UO2 2+ on poly(N,N-diethylacrylamide-co-acrylic acid): effects of pH, ionic strength, initial uranyl concentration, and temperature

We prepared poly(N,N-diethylacrylamide-co-acrylic acid) (P(DEA-co-AA)) microgels which could efficiently remove UO₂ ²⁺ from aqueous solutions. In this study, the effect of adsorption parameters such as pH value, adsorbent dose, shaking time, and temperature has investigated. It is found that the pseudo-second-order model is more suitable for our experiment. The adsorption kinetic data indicated that the chemical adsorption was the swiftness processes, the adsorption equilibrium could be achieved within 30 min. And there are very good correlation coefficients of linearized equations for Langmuir isotherm model, which indicated that the sorption isotherm of the hydrogel for UO₂ ²⁺ can be fitted to the Langmuir isotherm model. The adsorption process was spontaneous (?G ⁰ < 0) and exothermic (?H ⁰ < 0). The adsorbed UO₂ ²⁺ can be desorbed effectively by 0.1 M HNO₃ and the adsorption capacity is not significantly reduced after five cycles. Present study suggests that this P(DEA-co-AA) can be used as a potential adsorbent for sorption UO₂ ²⁺ and also provide a simple, fast separation method for removal of UO₂ ²⁺ ions from aqueous solution.     

Development of cloud point extraction using pH-sensitive hydrogel for preconcentration and determination of malachite green

A novel and sensitive cloud point extraction procedure using pH-sensitive hydrogel was developed for preconcentration and spectrophotometric determination of trace amounts of malachite green (MG). In this extraction method, appropriate amounts of poly(styrene-alt-maleic acid), as a pH-sensitive hydrogel, and HCl were added respectively into the aqueous sample so a cloudy solution was formed. The cloudy phase consists of hydrogel particles distributed entirely into the aqueous phase. Organic or inorganic compounds having the potential to interact with polymer particles (chemical interaction or physical adsorption) could be extracted to cloudy phase. After centrifuging, these particles of hydrogel were sedimented in the bottom of sample tube. The sedimented hydrogel-rich phase was diluted with acetonitrile and its absorbance was measured at 617 nm (λ_max of malachite green in hydrogel). Central composite design and response surface method were applied to design the experiments and optimize the experimental parameters such as, concentration of hydrogel and HCl, extraction time and salting out effect. Under the optimum conditions, the linear range was 1 × 10⁻⁸-5 × 10⁻⁷ mol L⁻¹ malachite green with a correlation coefficient of 0.992. The limit of detection (S/N = 3) was 4.1 × 10⁻⁹ mol L⁻¹. Relative standard deviation (RSD) for 7 replicate determinations of 10⁻⁷ mol L⁻¹ malachite green was 3.03%. In this work, the concentration factor of 20 was reached. Also the improvement factor of the proposed method was 23. The advantages of this method are simplicity of operation, rapidity and low cost.     

Tough poly(L-DOPA)-containing Double Network Hydrogel Beads with High Capacity of Dye Adsorption

Developing a low-cost and well-recyclable adsorbent with high adsorption capacity is greatly desirable in dye wastewater treatment. Here, we demonstrate a kind of novel tough and reusable hydrogel beads with quite high capacity of dye adsorption via incorporating mussel-bioinspired poly(L-DOPA) (PDOPA) into alginate/poly(acrylamide) double network (DN) hydrogels. The synthesized PDOPA nanoaggregates were introduced into the DN hydrogels by simple one-pot mixing with the monomers prior to polymerization. The fabricated hydrogel beads exhibited high mechanical strength and good elastic recovery due to the interpenetrating Ca²⁺-alginate and poly(acrylamide) networks. It was shown that the beads exhibited relatively high dye adsorption capacity compared to other adsorbents reported in literature, and the introduction of PDOPA with an appropriate amount raised the adsorption capacity. It is believed that the addition of PDOPA and the matrix of double network architecture contributed synergistically to the high adsorption capacity of hydrogel beads. Moreover, the desorption of dyes could be easily realized via rinsing in acidic water and ethanol solution. The hydrogel beads remained the high adsorption capacity even after 5 times of adsorption and desorption cycles. This tough and stable hydrogel with high adsorption capacity may have potential in treatment of dye wastewater released by textile dyeing industry.