Necklace-like ferroferric oxide (Fe3O4) nanoparticle/carbon nanofibril aerogels with enhanced lithium storage by carbonization of ferric alginate

Preparation of magnetic sodium alginate/sodium carboxymethylcellulose interpenetrating network gel spheres and use in superefficient adsorption of direct dyes in water

The rapid development of the printing and dyeing industry has led to the production of a large amount of high-density printing and dyeing wastewater, and technology for its effective treatment has become a focus of research. To construct a polymeric adsorbent material with abundant functional groups for the efficient adsorption of dye wastewater, a novel magnetic sodium alginate/carboxymethylcellulose interpenetrating network gel sphere (Fe3O4@SA/CMC-Fe) was prepared by co-blending sodium alginate (SA) and sodium carboxymethylcellulose (CMC) with Fe3O4; Fe3O4@SA/CMC-Fe was characterized by SEM-EDS, XRD, TGA, FT-IR, UV-Vis, VSM, BET-BJH and XPS. Static adsorption experiments showed that the optimal rates for adsorption of DV 51 and DR 23 from solutions with neutral pH values by Fe3O4@SA/CMC-Fe were up to 96 %, the adsorption process exhibited a Langmuir adsorption isotherm, and the dynamic adsorption process was accurately described by the pseudo-second-order kinetic model. A thermodynamic study showed that the adsorption reactions were all spontaneous exothermic reactions with increasing entropy. The mechanism for adsorption of the dyes by Fe3O4@SA/CMC-Fe involved hydrogen bonding, complexation and electrostatic adsorption. In summary, Fe3O4@SA/CMC-Fe is a green, simple, recyclable and highly efficient magnetic adsorbent that is expected to be widely used in treating dye wastewaters over a wide pH range.

Synthesis of cellulosic and nano-cellulosic aerogel from lignocellulosic materials for diverse sustainable applications: a review

Cellulosic aerogels are sustainable, biodegradable, and ultra-light porous materials with three-dimensional networks having high specific surface area. Depending on the source of precursor materials, they are categorized into plant-based aerogel, bacterial cellulosic aerogel. Different types of aerogels are also produced from microcrystalline cellulose (MCC), nanocrystalline cellulose (NCC), cellulose microfibril (CMF) and cellulose nanofibril (CNF). Furthermore, inorganic and organic substances are embedded to produce hybrid aerogel or composite aerogel for the enhancement of its performance in various fields. Mixing, gelation, solvent exchange, and drying (e.g., super critical carbon dioxide or freeze drying) are the basic steps involved in cellulosic aerogel synthesis. Based on the composition of precursors during aerogel synthesis, cellulosic aerogels have broad applications in various fields such as adsorbents, electrodes, sensors, captive deionization materials, catalysts, drug delivery, thermal and sound insulating materials. This review provided consolidated information on: (i) classification of cellulosic aerogels based on the sources of raw materials, (ii) processes involved to produce the cellulosic aerogel, (iii) cellulosic aerogel synthesized from MCC, NCC, CMF and CNF, (iv) nano particle doped cellulosic aerogel, and (v) its application in various field with future perspectives.

Super-efficient removal and adsorption mechanism of anionic dyes from water by magnetic amino acid-functionalized diatomite/yttrium alginate hybrid beads as an eco-friendly composite

The development of eco-friendly, large-capacity and easy-to-separate adsorbent materials has always been the focus and difficulty of adsorption technology in wastewater treatment applications based on the characteristics of dye wastewater. Therefore, in this study, a green magnetic glycine(Gly)-functionalized diatomite(Dia)/yttrium alginate (Y-SA) hybrid bead composite (Dia-Gly-Y-SA@Fe₃O₄) was synthesized by the droplet polymerization, and characterized by various modern analytical techniques. The adsorption performance and adsorption mechanism of the composite were evaluated and elucidated by the removal of anionic dyes direct Blue 106 (DB 106), Congo red (CR) and direct red 13 (DR 13) from water. The results show that the composite is a macroparticle gelpolymer with an average particle size of about 1.5 mm, flower-like fold surface structure, abundant porosity and sensitive magnetic response, and displays ultrastrong adsorption ability for three dyes. The adsorption equilibrium of each dye can be reached quickly within 30 min, and the removal efficiency is more than 95% at pH 2.0 and decreases slightly with pH up to 9.0. The adsorption processes could be explained by the Pseudo-second-order rate equation well. All isotherm data fitted the Langmuir model well, and the maximum adsorption capacities were 1635, 2359 and 1165 mg/g for DB 106, CR and DR 13 at 298 K, respectively. The ultrastrong adsorption performance was due to the multisite interaction of physicochemical action and various hydrogen bonds between hybrid beads and dye anions. As a cost-effective magnetic macroparticle adsorbent prepared by natural ingredients, Dia-Gly-Y-SA@Fe₃O₄ composite exhibits much more stronger adsorption efficiency, better collectability and no secondary pollution than powder Dia, and would have a good application prospect for the purification of anionic dye wastewater with a wide pH range.

Exploration of Dual Ionic Cross-Linked Alginate Hydrogels Via Cations of Varying Valences towards Wound Healing

This study explored the synergistic effects of simultaneously using calcium and gallium cations in the cross-linking of alginate, detailing its effects on the characteristics of alginate compared to its single cation counterparts. The primary goal is to determine if there are any synergistic effects associated with the utilisation of multiple multivalent cations in polymer cross-linking and whether or not it could therefore be used in pharmaceutical applications such as wound healing. Given the fact divalent and trivalent cations have never been utilised together for cross-linking, an explanation for the mode of binding that occurs between the alginate and the cations during the cross-linking process and how it may affect the future applications of the polymer has been investigated. The calcium gallium alginate polymers were able to retain the antibacterial effects of gallium within the confines of the polymer matrix, possessing superior rheological properties, 6 times that of pure calcium and pure gallium, coupled with an improved swelling capacity that is 4 times higher than that of gallium alginate.

Ions-induced gelation of alginate: Mechanisms and applications

Alginate is an important natural biopolymer and has been widely used in the food, biomedical, and chemical industries. Ca²⁺-induced gelation is one of the most important functional properties of alginate. The gelation mechanism is well-known as egg-box model, which has been intensively studied in the last five decades. Alginate also forms gels with many other monovalent, divalent or trivalent cations, and their gelation can possess different mechanisms from that of Ca²⁺-induced gelation. The resulted gels also exhibit different properties that lead to various applications. This study is proposed to summarize the gelation mechanisms of alginate induced by different cations, mainly including H⁺, Ca²⁺, Ba²⁺, Cu²⁺, Sr²⁺, Zn²⁺, Fe²⁺, Mn²⁺, Al³⁺, and Fe³⁺. The mechanism of H⁺-induced gelation of alginate mainly depends on the protonation of carboxyl groups. Divalent ions-induced gelation of alginate show different selection towards G, M, and GM blocks. Trivalent ions can bind to carboxyl groups of uronates with no selection. The properties and applications of these ionotropic alginate gels are also discussed. The knowledge gained in this study would provide useful information for the practical applications of alginate.