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Given the poor mechanical properties of traditional adhesive hydrogels, many pieces of research have been focused on the preparation of adhesive hydrogels with good mechanical properties and expanded their application. In this study, a novel multifunctional adhesive hydrogel acrylated adenine/chitosan/polyacrylamide/ Fe(III)(Aa/CS/PAM/Fe(III)) hydrogels were prepared by a chemical and physical hybrid crosslinking strategy. The hydrogels can adhere to various solid substrate surfaces and show good mechanical properties. The highest adhesion strength of the hydrogel to wood reached 11.17 kPa with the fracture stress being 0.11 MPa and the toughness 0.84 MJ/m3. The hydrogels can be stretched to more than 1400% of their original length without breaking. Additionally, the hydrogels also have good repetitive adhesion and fatigue resistance. Due to the presence of Fe3+ and Cl−, hydrogels also have certain electrical conductivity, which can be used in human motion detection. [ABSTRACT FROM AUTHOR]

The removal of dye pollutants from dyeing and printing industrial wastewater is a very important issue, and different methods have developed for this purpose. Here, a hydrogel adsorbent gelatin/chitosan/β-cyclodextrin/sodium humate (GEL/CS/β-CD/SH) was developed by a simple method for removal of the reactive dyes in aqueous solutions. The hydrogel used as an adsorbent had a good adsorption to different kinds of organic dyes. In this work, we focused on the adsorption process of GEL/CS/β-CD/SH hydrogels to the cationic dyes methylene blue (MB) and anionic dyes acid fuchsin (AF), which are commonly used in the printing and dyeing industry. The effects of dye solution pH, ionic strength, temperature, and contact time were investigated in a batch system. The adsorption thermodynamic and dynamic behaviors towards AF and MB were investigated in detail. The adsorption process could occur spontaneously at environmental temperature. The results indicated that the maximum adsorption capacity of AF and MB reached 1666.7 mg/g and 714.3 mg/g, respectively. Moreover, the GEL/CS/β-CD/SH hydrogel could be degraded completely by microorganisms in the soil. Therefore, GEL/CS/β-CD/SH hydrogel has a potential application as an effective adsorbent for the treatment of dyeing wastewater. [ABSTRACT FROM AUTHOR]

A novel biodegradable porous hydrogel (gelatin/chitosan/β-cyclodextrin, GEL/CS/β-CD) was prepared via a simple one-pot polymerization of gelatin, chitosan, and β-cyclodextrin. The chemical structure, morphology, and thermal stability were characterized by Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and thermogravimetric (TG) analysis, respectively. Due to a great number of active groups, such as amino groups, hydroxyl groups, and carboxyl groups of the hydrogel providing enough adsorption active sites, the hydrogel had excellent adsorption performances. Various organic dyes, such as malachite green (MG), crystalline violet (CV), congo red (CR), methylene blue (MB), acid fuchsin (AF), and methyl orange (MO), could be effectively removed. For 30 mg /L of MB and AF, the removal rate was between 80.0 and 93.3%. At 298 K, the adsorption capacities of AF and MB were as high as 1111 mg/g and 667 mg/g, respectively. Adsorption thermodynamics study indicated that the adsorption was a spontaneous process with a negative ΔG. The adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model. Moreover, the GEL/CS/β-CD hydrogel had good biodegradability and it degraded completely in soil extract solution for 30 days. Herein, the prepared GEL/CS/β-CD hydrogel has potential application as a green and environmentally friendly adsorbent for the effective removal of organic dyes in printing and dyeing wastewater. [ABSTRACT FROM AUTHOR]

Herein, a porous, biodegradable and recyclable Gelatin/Chitosan hydrogel was fabricated as an effective adsorbent for organic pollutant. The synthesized Gelatin/Chitosan hydrogel composite was utilized in the removal of multiple dyes from aqueous solution using batch adsorption experiments. Among them, the Gelatin/Chitosan hydrogel had excellent adsorption capacity for various dyes. The maximum adsorption capacities for crystalline violet, methyl orange, acid fuchsin, congo red, malachite green, and methylene blue were 233.4 mg/g, 294.1 mg/g, 454.5 mg/g, 221.2 mg/g, 186.7 mg/g, and 209.2 mg/g, respectively. Moreover, the adsorption process could be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. The dye removal efficiency was still more than 50% after five consecutive cycles of dye adsorption–desorption. Therefore, the Gelatin/Chitosan hydrogel composite is a potential candidate towards dye pollution remediation owing to its environment friendliness, high adsorption potential and regeneration capability. [ABSTRACT FROM AUTHOR]

Adsorptive removal of dyes from industrial wastewater has attracted intensive interests in recent years. Hydrogels is a kind of promising adsorbent in dyes removal owing to the simple synthesis and convenient application. A biodegradable and recyclable gelatin hydrogel (GH) was synthesized by a convenient approach in this work. The as-prepared GH was used to remove dyes in aqueous solution. The results indicated that the GH had excellent adsorption capacity for various dyes and the maximum adsorption capacities of crystalline violet (CV), methyl orange (MO), acid fuchsin (AF), congo red (CR), malachite green (MG), and methylene blue (MB) were 138.89 mg/g, 72.63 mg/g, 66.29 mg/g, 64.84 mg/g, 64.64 mg/g, and 60.32 mg/g, respectively. Moreover, the dye removal efficiency was still more than 60% after five consecutive adsorption–desorption cycles and the shape of the GH kept well. Therefore, GH can be used as an environmentally friendly and effective adsorbent to remove virous dyes from printing and dyeing wastewater. [ABSTRACT FROM AUTHOR]

Highly swelling P(2-acrylamido-2-methyl-1-propanesulfonic acid- co-acrylic acid) (P(AMPS- co-AAc)) superabsorbent hydrogel was synthesized in aqueous solution by a simple one-step using glow-discharge electrolysis plasma technique, in which N,N'-methylenebisacrylamide was used as a crosslinking agent. The structure, thermal stability and morphology of P(AMPS- co-AAc) superabsorbent hydrogel were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. A mechanism for synthesis of P(AMPS- co-AAc) superabsorbent hydrogel was proposed. The reaction parameters affecting the equilibrium swelling (i.e., discharge voltage, discharge time, macroscopic temperature of the liquid phase, mass ratio of AMPS to AAc, and content of crosslinker) were systematically optimized to achieve a superabsorbent hydrogel with a maximum swelling capacity. The hydrogel formed which absorbed about 1,685 g HO/g dry hydrogel of the optimized product was used to study the influence of various pH values and salts solutions (NaCl, KCl, MgCl, and CaCl) on the equilibrium swelling. In addition, swelling kinetics in distilled water and on-off switching behavior were preliminarily investigated. The results showed that superabsorbent hydrogel was responsive to the pH and salts. [ABSTRACT FROM AUTHOR]