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To obtain nanofiltration membranes with high-performance in desalination and water purification, membranes of graphene oxide (GO), reduced graphene oxide (rGO) and GO/polyacrylamide (PAM) are prepared by a vacuum filtration method. This method is conducted in aqueous solution without any organic solvents. The graphene-based membranes (GBMs) are characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscopy, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. The hydrophilicity of GBMs is also evaluated by contact angle measurement. The interlayer spacing of GO membrane (0.85 nm), GO/PAM membrane (0.68 nm) and rGO membrane (0.36 nm) are measured by X-ray diffraction. The performance of the GBMs is evaluated on a dead-end filtration device. The water flux and retention of rhodamine B of the membranes are 399.04 L m−2 h−1 bar−1 and 85.03% (GO), 188.89 L m−2 h−1 bar−1 and 95.43% (GO/PAM), 85.85 L m−2 h−1 bar−1 and 97.06% (rGO), respectively. The GO/PAM membrane has the best comprehensive separation performance because of its proper interlayer spacing. GO/PAM membranes provide potential advantages in the design of high-performance membranes for molecular separation and water purification. [ABSTRACT FROM AUTHOR]

Polysaccharide-based materials created by physical processes have received considerable attention for biomedical applications. These structures are often made by associating charged polyelectrolytes in aqueous solutions, avoiding toxic chemistries (crosslinking agents). We review the principal polysaccharides (glycosaminoglycans, marine polysaccharides, and derivatives) containing ionizable groups in their structures and cellulose (neutral polysaccharide). Physical materials with high stability in aqueous media can be developed depending on the selected strategy. We review strategies, including coacervation, ionotropic gelation, electrospinning, layer-by-layer coating, gelation of polymer blends, solvent evaporation, and freezing–thawing methods, that create polysaccharide-based assemblies via in situ (one-step) methods for biomedical applications. We focus on materials used for growth factor (GFs) delivery, scaffolds, antimicrobial coatings, and wound dressings. [ABSTRACT FROM AUTHOR]

The shortage of water resources is a problem concerned by all countries in the world. In order to solve this problem of human survival, membrane separation technology promotes the development of water treatment field by virtue of its own advantages of high efficiency and low consumption. Membrane separation technology combined with nanomaterials has brought surprises to researchers. Graphene has unique structure and properties, making graphene and its derivatives have very good potential in water treatment and selective separation. Graphene‐based materials combined with traditional polymer materials have great potential in the field of membrane separation technology. In this article, we first introduce the preparation methods and transport mechanism of graphene‐based membranes, and then summarize the recent applications of graphene oxide/polymer composite membranes in water purification, gas separation, self‐cleaning, and oil–water separation. It is expected to become the next generation of functional composite membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47761. [ABSTRACT FROM AUTHOR]

To obtain pectin-based films is challenging due to the aqueous instability of polyelectrolyte mixtures. We overcome this issue by blending chitosan to pectin of high O -methoxylation degree (56%), followed by solvent evaporation. A durable film containing 74 wt% pectin content was produced and used as an adsorbent material toward Cu(II) ions. Kinetic and adsorption equilibrium studies showed that the pseudo-second-order and Sips isotherm models adjusted well to the experimental data, respectively. Langmuir isotherm indicated a maximum adsorption capacity (q m) for Cu(II) removal of 29.20 mg g−1. Differential scanning calorimetry, contact angle measurements, and X-ray photoelectron spectroscopy confirm the adsorption. The chemisorption plays an essential role in the process; thereby, the film reusability is low. After adsorption, the cytocompatible film/Cu(II) pair prevents the proliferation of Escherichia coli. • A physically crosslinked film contains high pectin content (74 wt%). • The film presents sorption capacity for Cu(II) ions of 29.20 mg g−1. • The chemisorption plays an essential role in the Cu(II) adsorption. • After adsorption, the film/Cu(II) has cytocompatibility for mammalian cells. • The film/Cu(II) prevents the spreading of E. coli on its surface. [ABSTRACT FROM AUTHOR]

Chitosan/alginate (CHT/ALG) and magnetic CHT/ALG/Fe 3 O 4 @SiO 2 composites were successfully prepared and used as adsorbent materials to remove Pb(II) from aqueous systems. New hydrogel beads were yielded through an unpublished methodology, examining the ionic strength of the chitosan (CHT) solutions. Polyvalent cations and toxic cross-linking agents such as glutaraldehyde and epichlorohydrin, frequently used to prepare CHT/ALG-based materials were not used in this study. The samples were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, thermal analysis (TAG/DSC), and zeta potential measurements. The addition of Fe 3 O 4 @SiO 2 (8 ± 3 nm) significantly modified the surface morphology of the composites. The CHT/ALG/Fe 3 O 4 @SiO 2 (8) hydrogel comprising the highest Fe 3 O 4 @SiO 2 content (8.0 wt%), displayed magnetic feature and zeta potential of −76.8 mV at pH 6.0. Kinetic and equilibrium adsorption studies reveal that Elovich and Redlich-Peterson mathematical models provide the best fits for the experimental data, respectively. The magnetic composite CHT/ALG/Fe 3 O 4 @SiO 2 (8) had maximum adsorption capacity (q m ) of 234.77 mg g −1 and adsorption/desorption cycles designed its reuse performance. The CHT/ALG/Fe 3 O 4 @SiO 2 (8) hydrogel was applied to treat battery effluent, achieving 99.04% Pb(II) removal, and diminishing the turbidity from 73 to 3.0 NTU. Wastewater and battery effluents contaminated with Pb(II) may be treated using an eco-friendly magnetic hybrid material based on CHT/ALG/Fe 3 O 4 @SiO 2 as the adsorbent. [ABSTRACT FROM AUTHOR]

[Display omitted] • HFPNM undergoes fluorescence quenching upon contact with Cu2+. • HFPNM is capable of accurately detecting 100–1000 nmol/L of Cu2+. • HFPNM can still be used as a Cu2+ sensor after 5 cycles of use. • HFPNM have the advantages of high detection sensitivity and environmental friendliness for recycling compared to other Cu2+ sensors. Cu2+ contamination in drinking water poses a threat to humans and the environment, and high concentrations of Cu2+ in human blood can induce disease. In recent years, fluorescence sensing of Cu2+ prepared from rare earth elements has been widely used for the accurate detection and quantification of Cu2+. In this paper, we report that europium (Eu), 4,4′,4-trimethyltriphenylamine (TTA), and 1,10-phenanthroline (Phen) undergo a complexation reaction to form the Eu(TTA) 3 Phen complex, which is loaded on SiO 2 nanoparticle to form SiO 2 @Eu3+. We use electrospinning of SiO 2 @Eu3+ and polyacrylonitrile (PAN) co-blended solutions to prepare PAN fluorescent nanofiber membranes (FPNM). FPNM are hydrolyzed hydrolysis to obtain Cu2+ sensors (HFPNM). The super hydrophilic surface of HFPNM undergoes fluorescence quenching upon contact with Cu2+. HFPNM is capable of accurately detecting 100–1000 nmol/L of Cu2+. Moreover, EDTA can be used as a reversible on/off switch for detection, and HFPNM can still be used as a Cu2+ sensor after 5 cycles of use. The HFPNM have the advantages of high detection sensitivity and environmental friendliness for recycling compared to other Cu2+ sensors. Fluorescent nanofibers can be combined with bio-nanotechnology allowing for promising future applications in Cu2+ detection and wearable smart fabrics. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new polymer-tannin adsorbet was created from the freezing-thawing method. • The acid black 172 and methylene blue were removed from aqueous solutions. • The adsorption was spontaneous and endothermic, being governed by physisorption. • Hydrophobic interactions are primarily responsible for dye removal. • Dye desorption quickly occurs in ethanol. This study presents an innovative adsorbent material obtained from the dialysis of an aqueous tannin derivative solution, followed by one freezing-thawing cycle at −4 °C. The freezing precipitated the tannin (459 ± 97 kDa) in water, yielding the solid adsorbent (d-TN) with aqueous insolubility and stability. The tannin derivative is mainly composed of amino-functionalized polyphenolic chains, but it comprises hydrolyzable tannins as well. The d-TN adsorbent removed the metal-complex acid black 172 (AcB) and methylene blue (MB) from water. Kinetic studies suggested that the nonlinear pseudo-first-order and pseudo-second-order models adjusted well to the experimental AcB and MB kinetic curves, respectively. Equilibrium studies indicated that the Sips model the experimental isotherms well, supporting maximum removal capacities (q m) of 119.1 mg/g for AcB and 310.2 mg/g for MB. The free Gibbs energy (ΔG0) was –3.33 kJ/mol for AcB adsorption and –4.16 kJ/mol for MB adsorption. The dye adsorption was spontaneous and endothermic, being governed by physisorption. Hydrophobic interactions are primarily responsible for dye removal. Therefore, dye desorption quickly occurs in ethanol. High-resolution XPS spectra characterized the d-TN surface after dye adsorption, confirming the adsorption of AcB composed of chromium ions (Cr3+). The eco-friendly d-TN can replace conventional adsorbents used to remove dyes from water. [ABSTRACT FROM AUTHOR]