Preparation of MWCNT/CoMn2O4 nanocomposite for effectual degradation of picric acid via peroxymonosulfate activation

In recent years, using nanomaterials based on multi-wall carbon nanotubes (MWCNT) through the activation of peroxymonosulfate (PMS) has attracted more attention to the degradation of organic pollutants. This research presented a new route for the synthesis of MWCNT/CoMn2O4 nanocomposite for the degradation of picric acid using advanced oxidation processes (AOPs). Firstly, CoMn2O4 nanoparticles were prepared and then loaded on MWCNT using ultrasonic waves. The results of various analyzes confirmed the successful loading of nanoparticles on carbon nanotubes. As the degradation process proceeds through oxidation processes, the high electronic conductivity of MWCNT and the active sites of Mn and Co in the nanocomposite play an essential role in activating PMS to generate reactive oxygen species (ROS). An investigation of the reaction mechanism in different conditions showed that the highest speed of picric acid decomposition in the presence of nanocomposite (98%) was in 47 min. However, the scavenger test showed that HO· and SO4·- radicals are more important in the degradation process. Meanwhile, the results showed that removing picric acid using MWCNT/CoMn2O4 was more effective than CoMn2O4 alone and confirmed the interaction effect of MWCNT nanotubes with AB2O4 nanocatalyst.

In-situ magnetic alginate coated chitosan core@shell beads with excellent performance in simulated and real wastewater treatment: Behavior, mechanisms, and new perspectives

Herein, a new hybrid magnetic core@shell biocomposite was prepared based on an alginate-bentonite core and a chitosan shell layer (mAB@Cs) where magnetic Fe3O4 NPs (50.7 nm) were in-situ generated on the surface via a simple non-thermal co-precipitation approach. The biocomposite has a high ability to magnetically separate and remove organic (ciprofloxacin (CPX)) and seven toxic inorganic (Cu2+, Cd2+, Co2+, Ni2+, Pb2+, Zn2+, and Hg2+) contaminants from simulated wastewater. Experimental results showed a CPX monolayer chemisorption with a Langmuir maximum adsorption capacity of 264.7 mg/g, maintained effectiveness up to the fifth cycle, and high removal rates of heavy metals ranging from 74.89 % to 99.86 % corresponding to adsorption capacities ranging from 12 to 20 mg/g. For a more accurate evaluation, the biocomposite was tested on a real urban wastewater sample (RWW) and it has manifested a noteworthy efficiency in removing a mixture of inorganic pollutants in terms of potassium K+ and orthophosphate phosphorous P-PO43-, and organic matter in terms of biological oxygen demand (BOD) and chemical oxygen demand (COD) with 46 %, 90 %, 84 %, and 64 % removal efficiencies, respectively. On top of this, a high inactivation rate of E. coli of the order of 96 % was recorded, making the prepared magnetic biocomposite adept for the simultaneous removal of emergent wastewater pollutants, from organic, inorganic, to pathogen microorganisms.

Construction of an allophane-based molecularly imprinted polymer for the efficient removal of antibiotic from aqueous solution

The widespread presence of ciprofloxacin (CIP) antibiotic in the water and soil poses substantial potential risks to the environment, threatening both human and animal health. In this study, we used nanoclay mineral allophane (Allo), β-cyclodextrin (β-CD) as a bifunctional monomer, and sodium alginate as a cross-linking agent, to prepare 3D porous Allo-β-CD molecularly imprinted polymers (MIPs) for the efficient removal of CIP from aqueous solution. The prepared Allo-β-CD MIP was characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and zeta potential measurements. The effects of initial concentration, time, pH level, and ion concentration on CIP removal dynamics were systematically studied. The adsorption kinetics and equilibrium data of CIP were well-fitted by the pseudo-second-order kinetic model and Langmuir isotherm models, respectively. The Allo-β-CD MIP can efficiently remove CIP from an aqueous solution, with a maximal adsorption capacity of 635 mg/g. It also has impressive recyclability, and enhanced selectivity, and is widely adaptable to various environmental conditions. The adsorption mechanisms of the as-prepared adsorbent include H bonds, hydrophobic interactions, surface complexation, and n-π EDA interactions. Given the experimental evidence, as-prepared adsorbent is therefore a promising candidate for the effective removal of CIP from the aquatic environment.

Synthesis and Characterization of Novel Magnetic Nano-Biocomposite Hydrogels Based on Starch-g-poly(acrylic acid) Reinforced by Cellulose Nanofibers for Cu2+ Ion Removal

One of the crucial challenges of the adsorption process is to recapture the adsorbent from the solution, especially for adsorbents in powder form. This study synthesized a novel magnetic nano-biocomposite hydrogel adsorbent to successfully remove Cu²⁺ ions, followed by convenient recovery and reusability of the adsorbent. The Cu²⁺ adsorption capacity of starch-g-poly(acrylic acid)/cellulose nanofibers (St-g-PAA/CNFs) composite hydrogel and magnetic composite hydrogel (M-St-g-PAA/CNFs) was investigated and compared in both bulk and powder forms. Results showed that Cu²⁺ removal kinetics and swelling rate were improved by grinding the bulk hydrogel into powder form. The kinetic data and adsorption isotherm were best correlated with the pseudo-second-order and Langmuir models, respectively. The maximum monolayer adsorption capacity values of M-St-g-PAA/CNFs hydrogels loaded with 2 and 8 wt % Fe₃O₄ nanoparticles in 600 mg/L Cu²⁺ solution were found to be 333.33 and 555.56 mg/g, respectively, compared to 322.58 mg/g for the St-g-PAA/CNFs hydrogel. Vibrating sample magnetometry (VSM) results demonstrate that the magnetic hydrogel that included 2 and 8 wt % magnetic nanoparticles exhibited paramagnetic behavior with the magnetization of 0.6-0.66 and 1-1.04 emu/g at the plateau, respectively, which showed a proper magnetic property and good magnetic attraction in the magnetic field for separating the adsorbent from the solution. Also, the synthesized compounds were characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Fourier transform infrared spectroscopy (FTIR). Finally, the magnetic bioadsorbent was successfully regenerated and reused for four treatment cycles.

Synthesis and Characterization of Hydrogel Droplets Containing Magnetic Nano Particles, in a Microfluidic Flow-Focusing Chip

Magnetic hybrid hydrogels have exhibited remarkable efficacy in various areas, particularly in the biomedical sciences, where these inventive substances exhibit intriguing prospects for controlled drug delivery, tissue engineering, magnetic separation, MRI contrast agents, hyperthermia, and thermal ablation. Additionally, droplet-based microfluidic technology enables the fabrication of microgels possessing monodisperse characteristics and controlled morphological shapes. Here, alginate microgels containing citrated magnetic nanoparticles (MNPs) were produced by a microfluidic flow-focusing system. Superparamagnetic magnetite nanoparticles with an average size of 29.1 ± 2.5 nm and saturation magnetization of 66.92 emu/g were synthesized via the co-precipitation method. The hydrodynamic size of MNPs was changed from 142 nm to 826.7 nm after the citrate group's attachment led to an increase in dispersion and the stability of the aqueous phase. A microfluidic flow-focusing chip was designed, and the mold was 3D printed by stereo lithographic technology. Depending on inlet fluid rates, monodisperse and polydisperse microgels in the range of 20-120 μm were produced. Different conditions of droplet generation in the microfluidic device (break-up) were discussed considering the model of rate-of-flow-controlled-breakup (squeezing). Practically, this study indicates guidelines for generating droplets with a predetermined size and polydispersity from liquids with well-defined macroscopic properties, utilizing a microfluidic flow-focusing device (MFFD). Fourier transform infrared spectrometer (FT-IR) results indicated a chemical attachment of citrate groups on MNPs and the existence of MNPs in the hydrogels. Magnetic hydrogel proliferation assay after 72 h showed a better rate of cell growth in comparison to the control group (p = 0.042).

"Smart" Delivery of Monoclonal Antibodies from a Magnetic Responsive Microgel Nanocomposite

"Smart" drug-delivery systems have significant potential to increase therapeutic efficiency, avoid undesired immune responses, and minimize drug side effects. Herein, we report on an innovative strategy to control the drug release process using two magneto-activated materials operating in the system. One of them, a polyvinyl alcohol (PVA)-diboronate (DB)-interpenetrated (IPN) alginate (Alg) microgel nanocomposite (PVA-DB-IPN-Alg) loaded with magnetic nanoparticles (MNPs), is acting as a drug-delivery system. The drugs or model (bio)molecules are loaded in the PVA-DB-IPN-Alg and then released upon receiving a magnetic signal. Another component of the system is represented with the MNPs functionalized with the glucose oxidase (GOx) enzyme, GOx-MNPs. The immobilized GOx biocatalytically produces H₂O₂ in the presence of glucose and oxygen, while the PVA-DB-IPN-Alg is decomposed/dissolved by reacting with H₂O₂. In the absence of a magnet, the biocatalytically produced H₂O₂ was mostly decomposed by the catalase enzyme present in the solution, thus not reaching the alginate microgel. Upon aggregation of these two types of particles induced by a magnet, the GOx-MNPs produced H₂O₂ in situ increasing locally its concentration, degrading the PVA-DB-IPN, thus opening pores in the alginate hydrogel resulting in a faster release of the entrapped payload. The release of the payload was confirmed in physiological complex environments, exemplified with human serum, demonstrating the stability and functionality of the materials in biological fluids. The release rate was strongly dependent on the concentration of catalase but not dependent on glucose concentration. The magneto-induced release process was confirmed for the small model protein payload, such as bovine serum albumin (BSA), as well as the trastuzumab monoclonal antibody (TmAb). For the latter, the release rate was up to 3.3 times higher in the presence of the magnet than in the absence of it in the human serum. We expect that the drug-delivery concept developed by these materials can find useful applications in the emerging field of "smart" materials in immunotherapy.

Alginate-Based Smart Materials and Their Application: Recent Advances and Perspectives

Nature produces materials using available molecular building blocks following a bottom-up approach. These materials are formed with great precision and flexibility in a controlled manner. This approach offers the inspiration for manufacturing new artificial materials and devices. Synthetic artificial materials can find many important applications ranging from personalized therapeutics to solutions for environmental problems. Among these materials, responsive synthetic materials are capable of changing their structure and/or properties in response to external stimuli, and hence are termed "smart" materials. Herein, this review focuses on alginate-based smart materials and their stimuli-responsive preparation, fragmentation, and applications in diverse fields from drug delivery and tissue engineering to water purification and environmental remediation. In the first part of this report, we review stimuli-induced preparation of alginate-based materials. Stimuli-triggered decomposition of alginate materials in a controlled fashion is documented in the second part, followed by the application of smart alginate materials in diverse fields. Because of their biocompatibility, easy accessibility, and simple techniques of material formation, alginates can provide solutions for several present and future problems of humankind. However, new research is needed for novel alginate-based materials with new functionalities and well-defined properties for targeted applications.

A Comparison Study on the Magneto-Responsive Properties and Swelling Behaviors of a Polyacrylamide-Based Hydrogel Incorporating with Magnetic Particles

This work investigates the mechanical properties, microstructures, and water-swelling behavior of a novel hydrogel filled with magnetic particles. The nanoparticles of magnetite (Fe₃O₄) and the micro-particles of carbonyl iron (CI) were selected and filled into a polyacrylamide (PAAM) hydrogel matrix to create two types of magnetic hydrogels. The isotropy and anisotropy of magnetic hydrogels are also presented in this study. The isotropic samples were cured without applying a magnetic field (MF), and the anisotropic samples were cured by applying an MF in the direction perpendicular to the thickness of the samples. The effects of the size, content, and inner structures of magnetic particles on the magneto-responsive and swelling properties of magnetic hydrogels were investigated. It was found that the magnetorheological (MR) effect of anisotropic samples was apparently higher than that of isotropic samples, and the hydrogels with CI exhibited a noticeable MR effect than those with Fe₃O₄. The storage modulus can be enhanced by increasing the filler content and size, forming an anisotropic structure, and applying an external MF. In addition, the magnetic hydrogels also have a swelling ability that can be tuned by varying the content and size of the particle fillers.

Development of Hydrogels with the Incorporation of Raphanus sativus L. Seed Extract in Sodium Alginate for Wound-Healing Application

Hydrogels prepared from polymers have been proposed for tissue regeneration and the treatment of bruise wounds. In this research work, we synthesized a Raphanus sativus L.-based wound-healing hydrogel with recognized antimicrobial activity for the healing of cutaneous lesions, drawing on its healing potential. A structural analysis was performed by Fourier transform infrared spectroscopy, confirming the interaction between sodium alginate and Raphanus sativus L. The surface morphology was studied by scanning electron microscopy. A swelling test showed that the T-1 hydrogel capability of absorption of the solution was superior compared to other synthesized samples. It was evident that the swelling tendency decreased as the Raphanus sativus L. seed extract concentration was reduced. In a thermogravimetric analysis, T-1 shows high thermal stability over other prepared hydrogel samples, enjoying a high content of seed extract compared with all samples. The prepared hydrogels were placed on the chick chorioallantoic membrane of fertilized chick eggs, and their healing capability was examined. All seed extracts containing hydrogels showed clear curative performance as compared to the control hydrogel, whereas their healing magnitude lessened as the extract ratio decreased. It was concluded from the results of the current study that the Raphanus sativus L. plant has wound-healing characteristics.

Biosynthesis of chitosan-coated iron oxide (Fe3O4) hybrid nanocomposites from leaf extracts of Brassica oleracea L. and study on their antibacterial potentials

In this study, we prepared chitosan (CS)-coated iron oxide (Fe₃O₄) nanocomposites (NCs) by employing the aqueous leaf extract of Brassica oleracea L. and evaluated its antimicrobial potential. The characterization of hybrid CS-Fe₃O₄ NCs was performed using Fourier-transform infrared spectroscopy (FTIR) analysis to evaluate the chemical bonding of chitosan to nanoparticles (NPs). X-ray photoelectron spectroscopy (XPS) studies revealed the presence of oxidation state elements Fe 2p, O 1s, N 1s, and C 1s, and the zeta potential analysis was found to have well-colloidal stability (+ 76.9 mV) of NCs. Transmission electron microscopy (TEM) analysis determined that CS-Fe₃O₄ NCs were spherical with an average particle size of 27 nm. The X-ray diffractometer (XRD) spectrum ascertained the crystallinity of the hybrid NCs and the vibrating sample magnetometer (VSM) inferred the ferromagnetic behavior of the synthesized NCs. Furthermore, the significant antibacterial efficacy of NPs was demonstrated against foodborne bacterial pathogens, such as Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), and the highest zone of inhibition was observed to be 11.5 mm and 13.5 mm in CS-Fe₃O₄ NCs, respectively. In comparison with Fe₃O₄ NPs, synergistic impacts of CS-Fe₃O₄ NCs displayed great antibacterial potential as exhibited by a clearly enlarged zone. Thus, CS-Fe₃O₄ NCs could be used as efficacious antimicrobial agents in food packaging and food preservation fields.

Natural Polymer-based Stimuli-responsive Hydrogels

The abilities of intelligent polymer hydrogels to change their structure and volume phase in response to external stimuli have provided new possibilities for various advanced technologies and great research and application potentials in the medical field. The natural polymer-based hydrogels have the advantages of environment-friendliness, rich sources and good biocompatibility. Based on their responsiveness to external stimuli, the natural polymer-based hydrogels can be classified into the temperature-responsive hydrogel, pH-responsive hydrogel, light-responsive hydrogel, electricresponsive hydrogel, redox-responsive hydrogel, enzyme-responsive hydrogel, magnetic-responsive hydrogel, multi-responsive hydrogel, etc. In this review, we have compiled some recent studies on natural polymer-based stimuli-responsive hydrogels, especially the hydrogels prepared from polysaccharides. The preparation methods, properties and applications of these hydrogels in the medical field are highlighted.

Revealing importance of particles' surface functionalization on the properties of magnetic alginate hydrogels

Iron/silica core-shell microparticles (IMPs) were functionalized by different functional groups including amine, glycidoxy, phenyl, and thiocyanate. Many of the IMPs modifications are reported for the first time. The resulting surface chemistry turned out to affect the properties of magnetic alginate hydrogels fabricated from sodium alginate and dispersed IMPs. Differences in magnetorheological properties of the obtained magnetic hydrogels can be at least partially attributed to the interactions between alginate and surface functionalities of IMPs. Density Functional Theory (DFT) calculations were carried out to get detailed insight into those interactions in order to link them with the observed macroscopic properties of the obtained hydrogels. For example, amine groups on the IMPs surface resulted in well-formed hydrogels while the presence of thiocyanate or phenyl groups - in poorly formed ones. This observation can be used for tuning the properties of various carbohydrate-based hydrogels.

Mechanistic investigation of ciprofloxacin recovery by magnetite-imprinted chitosan nanocomposite: Isotherm, kinetic, thermodynamic and reusability studies

Recovery of antibiotics from water and wastewaters has recently gained a great deal of attention due to their serious health and environmental problems. In this work, a magnetite imprinted chitosan polymer nanocomposites (Fe-CS NCs) were synthesized and applied for the adsorptive removal of ciprofloxacin (CIFO) as a model fluoroquinolone antibiotics. The composition and surface morphology of Fe-CS NCs were studied by SEM, BET, XRD, TEM, FTIR and zeta potential meter. Modelling and optimization of adsorption process were studied using response surface methodology (RSM). The reliability of the RSM models was tested by fitting the data. A comparative analysis of the results derived from the models demonstrated that the second-order model was the best. From the contour plotting results, at pH < pH_iep low adsorption rate was observed due to protonation of the chitosan NH₂ groups, whereas the adsorption rate was significantly enhanced and achieved to a maximum level at pH 6 due to the electrostatic interactions and hydrophobic interactions. Under optimum conditions, maximum removal efficiency and maximum adsorption capacity were obtained 68% and 142 mg/g, respectively. Well regenerability of Fe-CS together with its high capacity of fluoroquinolone antibiotics removal provide a promisable strategy to remediation of wastewaters.

Alginate-based composites for environmental applications: A critical review

Alginate-based composites have been extensively studied for applications in energy and environmental sectors due to their biocompatible, nontoxic, and cost-effective properties. This review is designed to provide an overview of the synthesis and application of alginate-based composites. In addition to an overview of current understanding of alginate biopolymer, gelation process, and cross-linking mechanisms, this work focuses on adsorption mechanisms and performance of different alginate-based composites for the removal of various pollutants including dyes, heavy metals, and antibiotics in water and wastewater. While encapsulation in alginate gel beads confers protective benefits to engineered nanoparticles, carbonaceous materials, cells and microbes, alginate-based composites typically exhibit enhanced adsorption performance. The physical and chemical properties of alginate-based composites determine the effectiveness under different application conditions. A series of alginate-based composites and their physicochemical and sorptive properties have been summarized. This critical review not only summarizes recent advances in alginate-based composites but also presents a perspective of future work for their environmental applications.

Chitosan-Iron Oxide Coated Graphene Oxide Nanocomposite Hydrogel: A Robust and Soft Antimicrobial Biofilm

We report a robust biofilm with antimicrobial properties fabricated from chitosan-iron oxide coated graphene oxide nanocomposite hydrogel. For the first time, the coprecipitation method was used for the successful synthesis of iron oxide coated graphene oxide (GIO) nanomaterial. After this, films were fabricated by the gel-casting technique aided by the self-healing ability of the chitosan hydrogel network system. Both the nanomaterial and the nanocomposite films were characterized by techniques such as scanning electron microscopy, FT-IR spectroscopy, X-ray diffraction, and vibrating sample magnetometry. Measurements of the thermodynamic stability and mechanical properties of the films indictaed a significant improvement in their thermal and mechanical properties. Moreover, the stress-strain profile indicated the tough nature of the nanocomposite hydrogel films. These improvements, therefore, indicated an effective interaction and good compatibility of the GIO nanomaterial with the chitosan hydrogel matrix. In addition, it was also possible to fabricate films with tunable surface properties such as hydrophobicity simply by varying the loading percentage of GIO nanomaterial in the hydrogel matrix. Fascinatingly, the chitosan-iron oxide coated graphene oxide nanocomposite hydrogel films displayed significant antimicrobial activities against both Gram-positive and Gram-negative bacterial strains, such as methicillin-resistant Staphylococcus aureus, Staphylococcus aureus, and Escherichia coli, and also against the opportunistic dermatophyte Candida albicans. The antimicrobial activities of the films were tested by agar diffusion assay and antimicrobial testing based on direct contact. A comparison of the antimicrobial activity of the chitosan-GIO nanocomposite hydrogel films with those of individual chitosan-graphene oxide and chitosan-iron oxide nanocomposite films demonstrated a higher antimicrobial activity for the former in both types of tests. In vitro hemolysis potentiality tests and MTT assays of the nanocomposite films indicated a noncytotoxic nature of the films, which conveyed the possibility of potential applications of these soft and tough films in biomedical as well as in the food industry.

Metal powder–pure water system for rational synthesis of metal oxide functional nanomaterials: a general, facile and green synthetic approach

A general and facile approach for synthesis of metal oxide functional nanomaterials based upon a metal powder–pure water system.

Efficient batch and column removal of Cr(vi) by carbon beads with developed nano-network

Alginate-derived carbon beads with a developed nano-network were successfully synthesizedviaa facile carbothermal reduction and acid-washing treatment. The product was used for Cr(vi) removal with easy recovery features.

Alginic acid/graphene oxide hydrogel film coated functional cotton fabric for controlled release of matrine and oxymatrine

The present study describes the fabrication of a functional cotton fabric and investigated the drug release capability of the functional cotton fabric.