Oxide Nanocomposite Hydrogels Research Articles

Adsorptive removal of cationic dyes from wastewater using a novel sodium alginate-based iron oxide nanocomposite hydrogel: DFT and advanced statistical physics modelling

A novel Sodium alginate-based hydrogel reinforced with varying Fe2O3 nanoparticles loading (NCH) was synthesized to remove cationic dyes methylene blue (MB) and crystal violet (CV). The NCH, with 5 % Fe2O3 loading, demonstrated optimal removal efficiency for both dyes. Detailed spectroscopic, microscopic, and spectrometric characterization techniques verified the nanocomposite structure and dye adsorption. Batch experiments revealed that at pH: 9, with a 20 mg 100 mL−1 adsorbent dose and times of 60 min for MB and 40 min for CV, with an initial concentration of 500 mg L−1, maximum adsorption capacities were achieved. MB and CV adsorption onto NCH showed distinct mechanisms: MB via physical interaction, CV via both physical and chemical interactions, including electrostatic forces and hydrogen bonding. Despite differences, the Langmuir-Freundlich model best fit the equilibrium isotherms, suggesting monolayer adsorption dominated, even with heterogeneous surface sites on NCH. A dual-site M2 statistical physics model revealed that MB and CV adsorption occurred via a multi-molecular vertical configuration on the binding sites, with heterogeneous adsorption sites contributing to dye uptake. Density functional theory demonstrated higher adsorption affinity for MB over CV, primarily due to hydrogen bonding and electrostatic interactions. NCH exhibited 80 % dye removal efficiency after five cycles, highlighting its potential for industrial effluent treatment.

Fast and effective hydroquinone adsorption by poly (2-dimethylaminoethyl methacrylate)/zinc oxide nanocomposite hydrogel in textile wastewater treatment

ABSTRACT Hydroquinone, a widely used phenolic compound, poses significant health and environmental risk and must be removed from wastewater. In this study, a novel adsorbent was developed for the removal of hydroquinone from aqueous solutions through the in-situ polymerisation of 2-(dimethylamino)ethyl methacrylate (DMAEMA) in the presence of zinc oxide nanoparticles (ZnO NPs). The kinetics of equilibrium swelling in deionised water (DI) and the effect of pH on the swelling behaviour were investigated. The structure of the nanocomposite hydrogel was analysed using FTIR, XRD, FESEM, EDX, TEM, and BET analysis. Various factors affecting the adsorption process, such as solution pH (2–12), initial concentration (25–200 mg/L), adsorbent dosage (4.0–80 mg/100 mL), NaCl concentration (0.1–1.0 mol/L), and temperature, were also investigated. The adsorption capacity of hydroquinone and the removal efficiency of PDMAEMA@ZnO reached 455 mg/g and 91%, respectively, at pH 11 within 15 minutes. Furthermore, PDMAEMA@ZnO showed a high removal efficiency of 99.47% in tests with real wastewater. Reusability studies showed that the adsorbent retained its ability to remove hydroquinone after four regeneration cycles. The adsorption data were well described by the pseudo-second order and Langmuir models. The thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. Therefore, the adsorbent, has considerable industrial potential as it quickly and efficiently adsorbs phenolic impurities such as hydroquinone from real textile wastewater.

Design and synthesis of chitosan/alginate/zinc oxide nanocomposite hydrogel beads as carrier for metformin hydrochloride

In the current study, nanocomposite hydrogel beads were prepared from chitosan, alginate and zinc oxide nanoparticles using sodium tripolyphosphate as the crosslinking agent by ionotropic gelation method. The resulting nanocomposite hydrogel beads were characterized by FT-IR, XRD, TGA and UV methods and the beads were found to be an effective delivery system for the regulated release of the antidiabetic drug metformin. The swelling properties, drug loading and encapsulation efficiencies of the metformin loaded nanocomposite beads were evaluated and these parameters were found to be influenced by the concentrations of chitosan, alginate and ZnO nanoparticles. The rate of release of the drug from the nanocomposite beads was determined by UV spectroscopic method at λmax 233 nm. An increase in the concentration of ZnO enhances the swelling properties but lowers the release rate. Swelling indices of the prepared formulations were in the range 5–150. Maximum swelling index of 150 was observed for the formulation with 3 % chitosan, 2 % alginate and 15 % zinc oxide NPs. However, a maximum release rate of 83.23 % was observed for the formulation without ZnO and with 3 % chitosan, 2 % alginate. Controlled drug release was observed for the drug loaded chitosan/alginate/ZnO, hydrogel beads. The zinc oxide nanoparticles improved the in vitro α-glucosidase inhibitory activity of the formulations and the formulation with 5 % ZnO exhibited a maximum α-glucosidase inhibition rate of 62.92 %. The incorporation of ZnO nanoparticles enhanced the antioxidant properties of the formulations. The cell viability values of the samples were evaluated using L929 mouse fibroblast cells which confirmed the nontoxic nature of the samples. Dinitrosalicylic acid (DNS) studies proved that the prepared nanocomposites are biodegradable.

An Ammonia Gas Sensor Based on Reduced Graphene Oxide Nanocomposite Hydrogels

AbstractA flexible gas sensor based on nanocomposite has been developed and characterized for detecting ammonia gas (NH3) in the atmosphere. This sensor utilizes nanocomposite hydrogels composed of Arabic gum (AG), acrylic acid (AAc), reduced graphene oxide (RGO), and silver nanoparticles (AgNPs). Various techniques, including FTIR (Fourier Transform Infrared Spectroscopy), AFM (Atomic Force Microscopy), XRD (X‐ray Diffraction), SEM (Scanning Electron Microscopy), XRF (X‐ray Fluorescence), TGA (Thermo‐gravimetric Analysis), DSC (Differential Scanning Calorimetry), were used to evaluate the sensor‘s properties. The nanocomposite hydrogels showed exceptional swelling ability (597 %), advantageous for accommodating gas molecules like NH3. The Polymerization and network formation percentages of 31 % and 56 %, respectively, suggest a robust hydrogel matrix structure. When tested for NH3 gas sensing at room temperature, the RGO/AgNPs/AGPAAc‐hydrogel exhibited high sensitivity and stability compared to other variants across gas concentrations ranging from 0 to 100 ppm. The improved performance of the physiochemical properties of the nanocomposite hydrogels might be attributed to the combined effect of AgNPs and RGO, which likely enhance sensitivity and stability. Selectivity tests conducted for three gases at room temperature revealed that the sensor response was highly selective to NH3 at a concentration of 50 ppm. Furthermore, the sensor demonstrated consistent performance over time. These findings suggest potential applications in environmental monitoring and industrial safety, with the possibility of contributing to advancements in gas sensing technology and addressing environmental and safety concerns.

Multifunctional Self-Assembled Block Copolymer/Iron Oxide Nanocomposite Hydrogels Formed from Wormlike Micelles.

This article reports the preparation of multifunctional magnetic nanocomposite hydrogels formed from wormlike micelles. Specifically, iron oxide nanoparticles were incorporated into a temperature responsive block copolymer, poly(glycerol monomethacrylate)-b-poly(2-hydroxypropyl methacrylate) (PGMA-b-PHPMA), and graphene oxide (GO) dispersion at a low temperature (∼2 °C) through high-speed mixing and returning the mixture to room temperature, resulting in the formation of nanocomposite gels. The optimal concentrations of iron oxide and GO enhanced the gel strength of the nanocomposite gels, which exhibited a strong magnetic response when a magnetic field was applied. These materials retained the thermoresponsiveness of the PGMA-PHPMA wormlike micelles allowing for a solid-to-liquid transition to occur when the temperature was reduced. The mechanical and rheological properties and performance of the nanocomposite gels were demonstrated to be adjustable, making them suitable for a wide range of potential applications. These nanocomposite worm gels were demonstrated to be relatively adhesive and to act as strain and temperature sensors, with the measured electrical resistance of the nanocomposite gels changing with applied strain and temperature sweeps. The nanocomposite gels were found to recover efficiently after the application of high shear with approximately 100% healing efficiency within seconds. Additionally, these nanocomposite worm gels were injectable, and the addition of GO and iron oxide nanomaterials seemed to have no significant adverse impact on the biocompatibility of the copolymer gels, making them suitable not only for 3D printing in nanocomposite engineering but also for potential utilization in various biomedical applications as an injectable magnetic responsive hydrogel.

Adsorption studies of toxic organic pesticides from aqueous medium by sodium alginate‐cl‐poly (allyl amine‐co‐acrylic acid)/copper oxide nanocomposite hydrogel: Isotherms, kinetics, and thermodynamics

AbstractThe sodium alginate (SAG) cross‐linked poly (allyl amine‐co‐acrylic acid)/copper oxide [SAG‐cl‐poly(AAM‐co‐AA)/CuO] nanocomposite hydrogel (SNCHG) was synthesized by using a free radical initiated cross‐linked copolymerization process in‐situ. Several characterization techniques namely FTIR, PXRD, FESEM with EDAX, TGA, and BET analysis were employed to characterize the synthesized SNCHG. Water swelling properties together with swelling kinetics of SNCHG were evaluated. The highest swelling (35% after 30 minutes) was found at pH 8. The adsorption property of the developed nanocomposite hydrogel (SNCHG) was evaluated in three pesticides' solution namely chlorpyrifos (CP), phosalone (PL), and 4,4'‐ dichloro diphenyl dichloro ethane (DD) in water medium. Several factors affecting the adsorption like solution pH, time of adsorption, amount of pesticides, etc. were evaluated. The maximum adsorption were found to be 96.9% for CP at pH 7, 95.85% for PL at pH 7, and 86.72% for DD at pH 4. Pseudo‐second order kinetics and both Freundlich and Dubinin–Radushkevich adsorption isotherms were followed in all the three cases. Maximum adsorption capacity (Qm) were found to be 507.61, 158.22, and 132.97 mg g−1 for CP, PL, and DD, respectively. The adsorption process was endothermic in nature and spontaneous.Highlights A novel CuO Nps embedded sodium alginate‐based hydrogel is developed. Increment of surface area and water swelling property are illustrated. The hydrogel exhibits excellent adsorption property towards pesticides. The observed affinity of adsorption is chemisorption.

Novel microbicide graphene oxide nanocomposite hydrogel against herpes simplex virus

Hydrogels are 3D network soft materials capable of swelling in water. Graphene oxide (GO) hydrogels have garnered attention due to their inherent biocompatibility, large surface area, bioavailability, and excellent mechanical properties. In this study, we report the synthesis and characterization of a novel hydrogel nanocomposite incorporating GO, chitosan nanoparticles (CS NPs), zinc oxide nanoparticles (ZnO NPs), and tannic acid (TA). TA acts as a green crosslinker for GO, a binder for ZnO NPs, and a material known for its antiviral and antimicrobial activity. GO sheets were used to stabilize ZnO NPs and prevent their agglomeration. We evaluated the antimicrobial and antiviral activity of the novel nanocomposite hydrogel against pathogenic microbes and the herpes simplex virus (HSV-1), which revealed strong inhibition effects.We demonstrated that the hydrogel nanocomposite incorporating TA, CS NPs,ZnO NPs, and GO sheets displays novel antimicrobial properties. The hydrogel nanocomposite presents a versatile framework for the integration of antibacterial activity against Gram-positive and Gram-negative bacteria, as well as antifungal and anti-Herpes virus (HSV-1) applications. Furthermore, this hydrogel exhibited superior antiviral activity against the HSV-1 virus, with nearly 86% inhibition. The hydrogels possess pH-responsive properties with no cytotoxic effects and represent an up-to-date strategy for improving antiviral surfaces, personal protective equipment (PPE), and sprays based on their excellent swelling properties.

Ultrasound-assisted adsorption of chlorpyrifos from aqueous solutions using magnetic chitosan/graphene quantum dot‑iron oxide nanocomposite hydrogel beads in batch adsorption column and fixed bed

Chlorpyrifos is a hazardous material that pollutes the environment and also poses risks to human health. Thus, it is necessary to remove chlorpyrifos from aqueous media. In this study, chitosan-based hydrogel beads with different content of iron oxide-graphene quantum dots were synthesized and used for the ultrasonic-assisted removal of chlorpyrifos from wastewater. The results of batch adsorption experiments showed that among the hydrogel beads-based nanocomposites, the chitosan/graphene quantum dot‑iron oxide (10) indicated a higher adsorption efficiency of about 99.997 % at optimum conditions of the response surface method. Fitting the experimental equilibrium data to different models shows that the adsorption of chlorpyrifos is well described by the Jossens, Avrami, and double exponential models. Furthermore, for the first time, the study of the ultrasonic effect on the removal performance of chlorpyrifos showed that the ultrasonic-assisted removal of chlorpyrifos significantly reduces the equilibration time. It is expected that the ultrasonic-assisted removal strategy can be a new method to develop highly efficient adsorbents for rapid removal of pollutants in wastewater. Also, the results of the fixed bed adsorption column showed that the breakthrough time and exhausting time of chitosan/graphene quantum dot‑iron oxide (10) were equal to 485 and 1099 min, respectively. And finally, the adsorption-desorption study showed the successful reuse of adsorbent for chlorpyrifos adsorption in seven runs without a significant decrease in adsorption efficiency. Therefore, it can be said that the adsorbent has a high economic and functional potential for industrial applications.

Graphene Oxide Nanocomposite Hydrogels Based on Mucilage Extracted from Ocimum basilicum Seeds Grafted by Acrylate Polymers; Assay on Physicochemical Properties

Graphene Oxide Nanocomposite Hydrogels Based on Mucilage Extracted from Ocimum basilicum Seeds Grafted by Acrylate Polymers; Assay on Physicochemical Properties

Phosphonated graphene oxide-modified polyacrylamide hydrogel electrolytes for solid-state zinc-ion batteries

Compared to rigid batteries using liquid electrolytes, solid-state batteries (SSBs) offer several advantages: flexibility, prevention of leakage, suppression of dendritic formation and hydrogen evolution, as well as minimization of cathode active material dissolution. For the materialization of real-life SSBs, gel polymer electrolytes (GPEs) are among promising candidates. However, development of GPEs with satisfying ionic conductivity and mechanical endurance is challenging. Herein, we report on the development of polyacrylamide (PAM)/phosphonated graphene oxide (PGO) nanocomposite hydrogel electrolytes for zinc-ion batteries; PGO acts as the filler through in-situ polymerization of acrylamide in an aqueous suspension of PGO. The synthesized PAM/PGO hydrogel exhibits high ionic conductivity of 31.0 mS/cm at 30 °C compared to that of PAM (13.8 mS/cm) and PAM-GO (20.8 mS/cm). The higher ionic conductivity of PAM-PGO can be attributed to its higher hydrophilicity and electrolyte storage capacity along with its lower activation energy for ionic conduction (7.2 KJ/mol K) in comparison with that of PAM (10.1 KJ/mol K) and PAM-GO (10.2 KJ/mol K). The interaction between water against PAM, PAM-GO and PAM-PGO is investigated via density-functional theory (DFT). The MnO2-based zinc-ion battery assembled using PAM-PGO as electrolyte shows high initial capacity of 240 mAh/g, losing only 4 and 15% of its capacity after 100 and 145 cycles, respectively. Results demonstrate promising potential of PAM-PGO as a solid-state electrolyte for flexible battery applications.

Cationic Dye Removal (Methylene Blue) from Aqueous Solution Using the Ecologically Friendly Alginate/Hydroxyapatite/Graphene Oxide Nanocomposite Hydrogel Beads

Cationic Dye Removal (Methylene Blue) from Aqueous Solution Using the Ecologically Friendly Alginate/Hydroxyapatite/Graphene Oxide Nanocomposite Hydrogel Beads

Super-strong and anti-tearing poly(vinyl alcohol)/graphene oxide nano-composite hydrogels fabricated by formation of multiple crosslinking bonding network structure

As load-bearing material in biomedical-applications as cartilage replacement, artificial meniscus and tendons, etc., poly(vinyl alcohol) (PVA)/graphene oxide (GO)-tannic acid (TA) nano-composite hydrogels with multiple-crosslinking network were fabricated by establishing freezing/thawing-annealing-swelling method. By TA anchoring, PVA molecules were grafted onto GO surface efficiently, and strong interfacial interaction led to exfoliation and uniform distribution of GO in matrix. By introducing annealing process, the crystallinity and crystallite size of PVA increased and introducing GO-TA led to more perfect and denser crystalline structure, while physical crosslinking network centered on GO-TA and hydrogen bond-abundant crystalline phase formed, resulting in increasing crosslinking density of hydrogel. By further swelling in CaCl2 aqueous solution, hydroxyl-Ca2+ coordination formed, and multiple-crosslinking network was constructed with high crosslinking density. The tensile strength and fracture toughness of composite hydrogel were remarkably improved, reaching 14.38 MPa/27.93 MJ/m3, approximately 11-/26-fold higher than those of neat PVA hydrogel, while tearing strength was significantly enhanced, attributed to high energy dissipation through unzipping multiple interactions.

Enhanced adsorption performance of chitosan/cellulose nanofiber isolated from durian peel waste/graphene oxide nanocomposite hydrogels

In this work, nanocomposite hydrogels were prepared from cellulose nanofiber (CNF) isolated from durian peel waste combined with chitosan (CS) and graphene oxide (GO) with glutaraldehyde as a cross-linking agent. The morphology, structure and thermal properties of the nanocomposites were investigated using Scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction and thermogravimetric analysis techniques. Accordingly, the nanocomposite hydrogels was used for the removal of methylene blue (MB) dye and levofloxacin hemihydrate (LFX) antibiotics pollutant. It was found that the presence of GO in the matrix further enhances the adsorption capacities of 32.05 and 11.01 mg/g for MB and LFX, respectively obtained from pseudo-second order kinetic model. In addition, the removal percentage for both MB and LFX were achieved > 85 % for CS/CNF/GO (6 mg/mL) hydrogels due to the strong electrostatic interaction with MB and LFX. This study revealed that the addition of GO into nanocomposites hydrogel effectively remove MB and LFX in aqueous solution with low cost processing, facile preparation, thus promising for future wastewater treatment.

Green synthesis, characterization, photocatalytic activity, and biological applications of gelatin-sodium alginate zinc oxide nanocomposite

The present study stated a green approach for synthesizing zinc oxide nanoparticles using Oldenlandia umbellata (Rubiaceae) plant extract, which was used as the biological reducing agent for synthesizing zinc oxide nanoparticles from zinc nitrate hexahydrate. The synthesized ZnO nanoparticles were loaded with Gelatin-Sodium alginate biopolymers to convert them into Gelatin-Sodium alginate-Zinc oxide (GSZnO) nanocomposite hydrogels. The UV–Visible spectroscopy showed maximum absorbance at 376 nm for ZnO Nanoparticles and 360 nm for GSZnO nanocomposite. Different functional groups in ZnO Nps and GSZnO nanocomposites are identified using FT-IR spectroscopy. The SEM analysis of ZnO Nps and GSZnO nanocomposites demonstrates the size in the range of 67–80 nm. DLS Particle size analysis shows 71 nm for ZnO.A NPs and 74 nm for GSZnO nanocomposites. XRD analysis proved the crystalline nature and sharp highest peak at 101) plane confirm the hexagonal shape. While the EDAX analysis confirmed the formation of zinc oxide in the nanoparticles. Antioxidant studies were carried out for ZnO.A Nps showed better antioxidant properties compared to plant extract. The antimicrobial activity of plant extract and ZnO.A Nanoparticles were done against Staphylococcus aureus, Proteus vulgaris, Aspergillus flavus, and Candida albicans. ZnO.A nanoparticles showed good photocatalytic activity of methylene red dye in the presence of visible light irradiation. GSZnO nanocomposite was studied for In-vitro cytotoxicity on Vero cells, The IC50 value for the GSZnO nanocomposite was 101.5 µg/ml.

Synthesis and catalytic evaluation of silver@nickel oxide and alginate biopolymer nanocomposite hydrogel beads

In this study, silver–nickel oxide/calcium alginate (Ag@NiO/Alg) hydrogel beads were synthesized by incorporating the nanomaterial into the polymer solution followed by their extrusion from a syringe to coagulating solution for crosslinking. The Ag@NiO/Alg beads formed through this procedure were characterized by different instrumental techniques. The catalytic efficiency of Ag@NiO/Alg was evaluated for the reduction of rhodamine B (RhB) and methyl orange (MO), in the presence of sodium borohydride. After applying various kinetic order equations to the experimental data, the reactions were found to follow pseudo-first order kinetics using the Ag@NiO/Alg catalyst. The apparent rate constant (kapp) was determined as 0.33358 min−1 and 0.20882 min−1 for the catalytic reduction of RhB and MO, respectively. Furthermore, reduction reactions were studied at varying dye concentration and catalyst dosages. The recovered catalyst was reused up to five cycles without significant drop in the activity.

Characterization of a Multi-responsive Magnetic Graphene Oxide Nanocomposite Hydrogel and Its Application for DOX Delivery

Nanocomposite hydrogels are one of the most important types of biomaterials which can be used in many different applications such as drug delivery and tissue engineering. Placement of nanoparticles within a hydrogel matrix can provide unique characteristics like remote stimulate and mechanical strength improvement. In this study, the synthesis of graphene oxide and graphene oxide nanocomposite hydrogel has been studied. Nanocomposite hydrogel was synthesized with carboxymethyl cellulose as a natural base, acrylic acid as a monomer, graphene oxide as a filler, ammonium persulfate as an initiator, and iron nanoparticles as a crosslinking agent. The effect of reaction variables such as the iron nanoparticles, graphene oxide, ammonium persulfate, and acrylic acid were examined to achieve a hydrogel with maximum absorbency. Doxorubicin, as an anti-cancer chemotherapy drug, was loaded on this hydrogel and the release of drug in a phosphate buffer solution with different pH was carried out. The structure of the graphene oxide and optimized hydrogel were confirmed by Fourier-transform infrared spectroscopy, Raman spectroscopy, X-Ray diffraction, scanning electron microscopy, and atomic force microscopy.

Fabrication of chitosan-aminopropylsilane graphene oxide nanocomposite hydrogel embedded PES membrane for improved filtration performance and lead separation

In the present study chitosan-aminopropylsilane graphene oxide (CS-APSGO) nanocomposite hydrogel was synthesized and utilized as a hydrophilic additive in different dosages (0.5, 1, 2 and 5 wt%) in fabrication of porous polyethersulfone (PES) membranes via the phase inversion induced process by immersion precipitation method for heavy metal ion and dye removal. The modified membranes were characterized using ATR-FTIR, AFM, SEM, water contact angle, overall porosity and mean pore radius evaluations and zeta potential measurement. The addition of CS-APSGO nanocomposite hydrogel to PES doping solutions enhanced membranes hydrophilicity and consequently pure water flux permeability. Filtration performance of the CS-APSGO embedded membranes showed promising antifouling properties during BSA filtration test (FRR> 90%) and 1 wt% membranes showed the highest pure water flux of 123.8 L/m2 h with BSA rejection more than 98% and removal capability more than 82% for lead (II) ion, 90.5% and 98.5% for C.I. Reactive Blue 50 and C.I. Reactive Green 19, respectively. Therefore, the CS-APSGO nanocomposite hydrogel blending in order to modification of PES-based membranes have a noticeable potential in improving filtration performance of blended membranes.

Collagen/chitosan-functionalized graphene oxide hydrogel provide a 3D matrix for neural stem/precursor cells survival, adhesion, infiltration and migration

To have therapeutic promise of neural stem/precursor cells (NS/PCs) an appropriate scaffold is mostly essential. This study was conducted to fabricate collagen (Col)/chitosan-functionalized graphene oxide (CSGO) nanocomposite hydrogel and evaluated it as scaffold for NS/PCs. Graphene oxide was first functionalized with chitosan and the obtained CSGO was then added to Col solution and the solution underwent hydrogel formation. GO sheets were exfoliated after CS functionalization and the CSGO was homogenously dispersed in Col hydrogel. CSGO addition resulted in hydrogels with higher porosity and smaller Col fibers. Furthermore, CSGO increased the gelation time and water absorption capacity while the degradation was decreased. Cell studies demonstrated higher viability of NS/PCs on Col/CSGO hydrogel comparing with Col and poly-l-lysine as control (Cnt). NS/PCs were also penetrated into the Col/CSGO hydrogel and showed more cell spreading, neurite outgrowth and inter-cell connections in comparison with Col hydrogel. In addition, the cells traveled longer distance on Col/CSGO hydrogels than on Col and Cnt, indicating excellent migration capacity of NS/PCs on Col/CSGO hydrogel. Our results indicate the potential Col/CSGO hydrogels as an appropriate scaffold for NS/PCs.

Rheology and direct write printing of chitosan - graphene oxide nanocomposite hydrogels for differentiation of neuroblastoma cells

The direct write printing method has gained popularity in synthesizing scaffolds for tissue engineering. To achieve an excellent printability of scaffolds, a thorough evaluation of rheological properties is required. We report the synthesis, characterization, rheology, and direct-write printing of chitosan - graphene oxide (CH - GO) nanocomposite hydrogels at a varying concentration of GO in 3 and 4 wt% CH polymeric gels. Rheological characterization of CH - GO hydrogels shows that an addition of only 0.5 wt% of GO leads to a substantial increase in storage modulus (G′), viscosity, and yield stress of 3 and 4 wt% of CH hydrogels. A three-interval thixotropy test (3ITT) shows that 3 wt% CH with 0.5 wt% GO hydrogel has 94% recovery of G′ after 7 sequential stress cycles and is the best candidate for direct-write printing. Neuronal cell culture on 3 wt% CH with 0.5 wt% hydrogels reveals that GO promotes the differentiation of SH-SY5Y cells.

Poly(vinyl alcohol)/graphene oxide nanocomposite hydrogel with catalytic activity: the removal behavior and dual adsorption/catalytic degradation mechanism for dye wastewater

AbstractThe treatment of dye wastewater with traditional adsorption materials usually proceeds slowly with low removal efficiency and without completely eliminating dye molecules, leading to secondary pollution. In this work, poly(vinyl alcohol)/graphene oxide@tetraamino iron phthalocyanine (PVA/GO@TAFePc) nanocomposite hydrogels with catalytic activity were prepared via an in situ crosslinking method. Through interfacial covalent and π–π interactions, TAFePc was loaded onto GO layers with a high loading ratio, and GO@TAFePc was exfoliated and uniformly dispersed in the matrix. With increasing GO@TAFePc hybrid content, the pore size increased and a loose network structure was formed for the hydrogels, while the specific surface area rose significantly by using the hydrogel in a dye removal process, the removal rate of methylene blue (MB) increased sharply with contact time, reaching 98% in the presence of H2O2 with good reusability, and high removal efficiency was achieved for different dyes. The large surface area of the hydrogel was beneficial for MB adsorption. Meanwhile, under catalysis of TAFePc, a large amount of high activity ·OH was produced by H2O2 so as to degrade the MB molecules rapidly. Therefore, the MB degradation process for the composite hydrogel was ascribed to a dual adsorption/catalytic degradation mechanism. © 2020 Society of Industrial Chemistry