Fabrication of carboxymethyl cellulose/graphene oxide/ZnO composite hydrogel for efficient removal of fuchsin dye from aqueous media

Hydrogels are hydrophilic, insoluble, and highly porous 3D networks capable of absorbing large amounts of water. This study aimed to develop a carboxymethyl cellulose/graphene oxide (CMC/GO) hydrogel, cross-linked with citric acid and modified with zinc oxide (ZnO) nanoparticles (CMC/GO/ZnO), synthesized via the sol-gel method. The formulated composite hydrogel samples were characterized by Fourier transmittance infrared spectroscopy (FTIR), scanning electron microscopy (SEM) analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermo-gravimetric analysis (TGA). The hydrogels were tested for the adsorption of basic fuchsin (BF) dye from the aqueous medium under various conditions, such as adsorbent dosage, contact time, pH, and temperature, using batch adsorption. The adsorption data best fit the Langmuir and Temkin models, with maximum adsorption capacity (qmax) of 172.41 mg/g for CMC/GO and 303.03 mg/g for CMC/GO/ZnO. Optimal adsorption occurred at pH = 6 and within 30 min. The process followed a pseudo-second-order kinetic model, and thermodynamic results indicated that the adsorption process is physical, endothermic and spontaneous. The COOH groups in the hydrogels enhanced affinity for cationic dyes through hydrogen bonding and electrostatic interactions. Thus, CMC/GO and CMC/GO/ZnO hydrogels are efficient and promising adsorbents for environmental remediation.

Study on the Effects of Low-Intensity Pulsed Ultrasound and Iron Ions for Proliferation and Differentiation of Osteoblasts

OBJECTIVE

This study involved the proliferation and differentiation of osteoblasts treated with low-intensity pulsed ultrasound (LIPUS) and iron (Fe3+) ions, respectively. The biological effects of LIPUS and Fe3+ ions on the proliferation and differentiation of osteoblasts were also evaluated.

METHODS

MC3T3-E1 cells were seeded in six-well plates with the medium, which contained different concentrations of Fe3+ (0, 100, 200, 300, 400, 500, 600 and 700 μg L-1, respectively). LIPUS treatment was directed at the bottom of the plate for 20 min at an intensity of 80 mW cm-2 every day.

RESULTS

Viability results showed that a dose of 400 μg L-1 Fe3+ ions had the best effect at promoting osteogenic proliferation in cell culture. The results of alkaline phosphatase staining and mineralization indicated that the differentiation of osteoblasts was promoted by LIPUS and Fe3+ ions. Fluorescence staining results showed that the number of cell nuclei in the LIPUS, Fe3+ and LIPUS-Fe groups increased by 37.20%, 55.81% and 89.76%, respectively. Migration data indicated that migration and proliferation rates were increased by LIPUS and Fe3+, and the results of protein expression indicated that LIPUS and Fe3+ may increase the expression of Wnt, β-catenin, and Runx2, hence promoting normal bone regeneration and development.

CONCLUSION

The combination of LIPUS (1.5 MHz, 80 mW cm-2) and Fe3+ accelerates the proliferation and differentiation of osteoblasts significantly compared with single-factor treatment (stimulated by LIPUS and Fe3+ ions, respectively). This study could establish a foundation for LIPUS-responsive biomaterials in the repair and regeneration of bone tissues.

Novel hollow beads of carboxymethyl cellulose/ZSM-5/ZIF-8 for dye removal from aqueous solution in batch and continuous fixed bed systems

Zeolitic imidazolate frameworks are a class of metal-organic frameworks that are topologically isomorphic with zeolites. In this study, bionanocomposites of carboxymethyl cellulose-based ZSM-5/zeolitic imidazolate framework (CMC/ZSM-5/ZIF-8) hollow beads with different compositions were synthesized and employed as an adsorbent for methylene blue removal from aqueous solution in batch and continuous fixed bed systems. FESEM, FTIR, XRD, and BET measurements have been employed for characterizing the synthetic bionanocomposites. The effect of time and concentration on adsorption processes, regeneration, and reuse investigations were performed. The equilibrium batch adsorption capacities for CMC, CMC/ZIF-8, CMC/ZSM-5, and CMC/ZSM-5/ZIF-8 adsorbents were 12.01, 13.06, 11.53, and 10.49 mg/g, respectively. The batch adsorption was investigated using pseudo-first-order, pseudo-second-order, intra-particle diffusion, and Elovich kinetic models and the results showed that all four adsorbents are consistent with all models but the pseudo-first-order model showed more consistency. The equilibrium continuous adsorption capacities for CMC, CMC/ZIF-8, CMC/ZSM-5, and CMC/ZSM-5/ZIF-8 adsorbents were 10.56, 11.87, 9.29, and 8.15 mg/g, respectively. The continuous adsorption was investigated by Thomas, Adam-Bohart, Yoon-Nelson, Wolborska, and Modified Dose Response kinetic models and the results showed that the adsorbents showed more consistency with models of Thomas, Yoon-Nelson, and Modified Dose Response. Besides, the generation process was successfully assessed in five steps.

A Novel Cellulose-Based Polymer for Efficient Removal of Methylene Blue

A novel cellulose-based cross-linked polymer, dicarboxymethyl cellulose (DCMC), has been synthesized and used for methylene blue (MB) removal. Inductively coupled plasma atomic emission spectrometry (ICP-AES), Fourier-transform infrared spectroscopy (FTIR), nitrogen porosimetry, and optical microscopy were employed to characterize the structure of the cellulose-based adsorbent. The number of carboxylate groups per gram of polymer (CG) was calculated with sodium content determined by ICP-AES. Systematic equilibrium and kinetic adsorption studies were performed to assess the polymer suitability for dye removal. The effect of pH on its adsorption capacity was also studied and the equilibrium adsorption data was analyzed using Langmuir, Freundlich, and Sips isotherms. At pH = 3, the adsorption isotherms followed the Langmuir model with a maximum adsorption capacity of 887.6 mg/g. At pH = 6.4, the adsorption isotherms produced S-shape curves and were best fitted with the Sips model. The maximum MB uptake increased to 1354.6 mg/g. Pseudo first-order and second-order models were used to fit the kinetic data. A pseudo second-order kinetic model provided the best correlation for the adsorption of MB onto DCMC. Adsorption coupled with membrane filtration achieved 95% methylene blue removal and DCMC can be successfully regenerated and reused in consecutive experiments.

Mesoporous activated carbon from starch for superior rapid pesticides removal

Pesticides contamination of water has caused considerable concern due to the potential hazard to human health. For the first time, mesoporous activated carbon from starch (ACS) was applied to remove pesticides from water. ACS could remove 11 pesticides rapidly (shake five times). The adsorption rates of ACS (>80%) for the 11 pesticides were higher than those of other adsorbents, including commercial activated carbon (AC), graphitised carbon black (GCB), C18, and primary secondary amine adsorbent (PSA). The mechanisms of the adsorption process for pyraclostrobin were also investigated. The pseudo-second-order model could better describe the adsorption for pyraclostrobin (R² = 0.99950). Langmuir model gave the best fit for the isotherm data (R² = 0.99899). Our findings demonstrate that oxygen-containing functional groups, N atom and π-bonding network of benzene promoted the adsorption. The adsorption efficiency of the ACS for 11 pesticides was still over 80% after five cycles.