Search Results (68)

Solar-driven interfacial evaporation offers a low-energy and sustainable route for seawater desalination and the purification of complex water matrices. However, freestanding hydrogel evaporators often suffer from insufficient mechanical robustness and interfacial salt accumulation under high-salinity conditions. Herein, a spunlace cotton nonwoven/sodium alginate/bamboo charcoal (SC/SA/BC) composite interfacial evaporator was fabricated through a facile impregnation–ionic crosslinking strategy, using a spunlace cotton nonwoven (SC) as the reinforcing scaffold, sodium alginate (SA) as the hydrophilic hydrogel matrix, and bamboo charcoal powder (BC) as the photothermal component. The Ca²⁺-crosslinked SA network immobilized the bamboo charcoal particles and formed continuous hydrated mass-transport pathways, while the spunlace fibrous network provided capillary water-supply channels and robust mechanical support. Consequently, SC/SA/BC exhibited substantially improved mechanical performance compared with the freestanding SA/BC hydrogel. Under 1 sun irradiation using a 3.5 wt% NaCl solution, SC/SA/BC achieved an evaporation rate of approximately 1.80 kg m⁻² h⁻¹ and maintained stable performance during 8 h of continuous operation. The evaporation–condensation process markedly reduced the concentrations of major ions in natural seawater and effectively retained nonvolatile dyes. Through the synergistic integration of a spunlace fibrous scaffold, a hydrated hydrogel network, and a bamboo-charcoal-based photothermal component, the proposed evaporator simultaneously achieved mechanical reinforcement, sustained water supply, efficient photothermal conversion, and salt-tolerant operation. This work provides a promising strategy for constructing structurally stable and readily fabricated solar interfacial evaporation materials. Full article

Natural functional polysaccharides are biodegradable, safe, and bioactive macromolecules that contribute significantly to food security. This review provides a systematic overview of their classification, structural characteristics, and applications in agricultural pest control and grain storage, with emphasis on their mechanisms of action and preparation methods. Key representatives including chitosan, alginate, β-glucan, and pectin function through multiple pathways: direct pest inhibition, induction of plant resistance, bioactive encapsulation, and physical barrier formation. Recent advances in extraction, purification, and advanced nuclear magnetic resonance (NMR) techniques—quantitative NMR (qNMR), diffusion-ordered spectroscopy (DOSY), and pure shift methods—are summarized. Challenges including batch-to-batch variability, high production costs, and regulatory hurdles are discussed and future perspectives on green production, precision structural tailoring, and nano-encapsulation are proposed. This review aims to guide the application of polysaccharide-based materials in insect pest management and food protection. Full article

Gastrointestinal mucus is the first barrier encountered by luminal nutrients, but conventional static models do not reproduce mucus deformation under dynamic luminal flow. Additionally, the effects of mucus purification and dietary components on mucus barrier function remain insufficiently characterized. To address these gaps, a dynamic gastrointestinal mucus simulator was developed to evaluate mucus permeability under continuous luminal flow and investigate the effects of mucus purification and dietary components. The results showed that the dynamic model produced an approximately twofold glucose permeability compared with the static model, while increasing luminal flow further enhanced glucose permeability. Phycocyanin exhibited approximately 10-fold lower permeability than glucose, demonstrating the sensitivity of the model to differences in molecular properties. Additionally, mucus purification may compromise its barrier function due to the loss of gel-forming components. Dietary calcium and fibers enhanced the mucus barrier through different mechanisms, with 10 mM calcium reducing phycocyanin permeability by approximately 42%, and 6% cellulose nanocrystals and 2% alginate reducing glucose permeability by approximately 79% and 37%, respectively, suggesting their potential for modulating nutrient mucopenetration. This study provides an effective tool for evaluating mucus permeability and highlights the mucus barrier as an underexplored pathway where dietary components may modulate nutrient mucopenetration. Full article

The development of hydrogel bioinks that combine structural stability with biological compatibility remains a major challenge in extrusion-based 3D printing for tissue engineering. In this proof-of-concept study, bacterial cellulose (BC) obtained from kombucha fermentation was explored as a sustainable nanofibrillar component for alginate/chondroitin sulfate (CS)/silicon-substituted hydroxyapatite (Si-HA) composite inks. Following alkaline purification, mechanical processing, and freeze-drying, BC was characterized by scanning electron microscopy (SEM), ATR-FTIR spectroscopy, and X-ray diffraction (XRD), revealing a highly entangled nanofibrillar architecture with high crystallinity (85.4%) and strong hydrogen-bonding potential. Four hydrogel formulations were developed as a comparative 2 × 2 matrix, contrasting BC-containing systems with methylcellulose (MC)-containing reference systems at two Si-HA loadings. Reduced-viscosity measurements of the uncrosslinked precursor formulations showed higher values at the lower Si-HA loading in both formulation series. All formulations could be extruded as acellular inks into grid-like constructs and retained identifiable macroporous architectures after ionic crosslinking. Swelling increased between 24 and 48 h, while mass loss remained limited after the initial 24 h incubation period. In direct-contact testing with L929 fibroblasts, cell viability remained above 84% after 48 h, meeting the ISO 10993-5 non-cytotoxicity criterion. These findings support the feasibility of incorporating physically processed kombucha-derived BC into alginate-based composite inks. Full article

Magnetic polymer nanocomposites (MPNCs) have attracted considerable attention as advanced multifunctional materials for water purification due to their high adsorption capacity, magnetic recoverability, and excellent reusability. This review presents a comprehensive overview of recent developments in the synthesis, characterization, and environmental applications of MPNCs for wastewater treatment. Particular emphasis is placed on the principal synthesis strategies, including in situ and ex situ approaches, and their influence on nanoparticle dispersion, interfacial interactions, and the physicochemical properties of the resulting nanocomposites. The review covers the most widely investigated magnetic nanomaterials, such as Fe₃O₄, γ-Fe₂O₃, CoFe₂O₄, ZnFe₂O₄, and other ferrites, incorporated into natural and synthetic polymer matrices including chitosan, cellulose, alginate, polyaniline, polypyrrole, poly(vinyl alcohol), and polystyrene. Advanced characterization techniques, including X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM/TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), and superconducting quantum interference device (SQUID) measurements, are discussed to evaluate the structural, chemical, thermal, and magnetic properties of these hybrid materials. The adsorption performance and underlying mechanisms of MPNCs for the removal of heavy metals, dyes, pharmaceutical compounds, organic pollutants, and oil contaminants are critically analyzed, highlighting the roles of polymer functionalization, nanocomposite architecture, and magnetic separation in enhancing treatment efficiency and reusability. In addition, the contribution of density functional theory (DFT) to understanding adsorption mechanisms and guiding the rational design of high-performance adsorbents is reviewed. Finally, current challenges and future perspectives, including green synthesis, multifunctional and stimuli-responsive materials, scalable manufacturing, and industrial implementation, are discussed. This review provides a comprehensive framework for the design and development of next-generation magnetic polymer nanocomposites for sustainable water remediation applications. Full article

The sustained expansion of printing and dyeing operations has led to the discharge of large volumes of organic wastewater containing dyes. The resulting environmental pollution demands urgent solutions, making the development of efficient and eco-friendly methods for the elimination of dyeing wastewater critically important. The combination of alginate hydrogel membranes with advanced oxidation processes (AOPs) for water purification represents an emerging approach in the current field of water treatment. In this study, a calcium alginate membrane was loaded with a glaze containing highly active cobalt oxide to fabricate a glaze-calcium alginate (Glaze-CaAlg) composite membrane. The membrane achieved stable degradation of Orange G dye under optimal conditions, and a series of tests were conducted under varying conditions using pollutant concentrations close to those found in real water bodies. Under optimal conditions (glaze loading = 2.5 mL, PMS = 0.3 mmol/L, cross-flow filtration mode), the membrane achieved a 93.7% degradation efficiency of Orange G (10 ppm) within 45 min, with hydroxyl radicals (·OH, ~79%) identified as the predominant reactive species. The Glaze-CaAlg membrane also exhibited excellent reusability, maintaining a degradation efficiency of over 80% for Orange G across five consecutive cycles. Furthermore, sodium citrate was employed to react with the Glaze-CaAlg membrane, enabling the recovery and secondary application of the glaze. Membranes re-fabricated from the recovered glaze showed mechanical strength and catalytic efficiency comparable to those of the pristine membrane. The Glaze-CaAlg membrane possesses high catalytic activity and good stability. This work offers a sustainable, cost-effective, and recyclable catalytic membrane that converts a traditional ceramic material into an advanced functional material for wastewater remediation, with great potential for practical application in the treatment of refractory organic pollutants. Full article

Excess phosphate in aquatic environments can trigger eutrophication and pose risks to ecosystem integrity and public health, even though phosphate is indispensable for plant growth. Herein, we report the fabrication of Zr-LDHs-PS hydrogel microspheres by in situ cross-linking zirconium–magnesium–iron layered double hydroxides (ZrMgFe-LDHs) with Polyvinyl alcohol (PVA) and sodium alginate (SA). The resulting bead-type adsorbent was designed to enable efficient phosphate capture from water while facilitating subsequent, controlled phosphate release. Benefiting from the cross-linking granulation strategy, the microspheres mitigate typical limitations of powdered adsorbents, including compaction, aggregation, and poor separability. General characterization (SEM, FT-IR, XPS, XRD, BET, TG, and zeta potential) elucidated the microstructure and surface chemical composition. The Zr-LDHs-PS microspheres exhibited a maximum experimental adsorption capacity of 51.313 mg/g. Kinetics data were best fitted by the pseudo-second-order model, and adsorption isotherms were subjected to the Freundlich model, pointing to heterogeneous, multilayer adsorption. Importantly, high phosphate selectivity was preserved despite the coexistence of competing anions (Cl⁻, NO₃⁻, and CO₃²⁻). After adsorption, the spent beads released phosphate gradually in water, highlighting their potential for dual functionality. Collectively, these results demonstrate that Zr-LDHs-PS hydrogel microspheres are promising candidates for extraction-based phosphate removal and resource recovery, with prospects for repurposing slow-release phosphate fertilizers to support sustainable plant nutrition. Full article

Sodium alginate was extracted from beach-cast Sargassum spp. collected along the coast of Puerto Progreso, Yucatán, Mexico, using two established pretreatment routes based on formaldehyde and ethanol. This study evaluates how extraction methodology controls alginate recovery, molecular structure, hydrogel rheology, macroscopic integrity, swelling behavior, and preliminary inorganic contaminant profiles. The ethanol-based route provided the highest extraction yield, reaching 19.87 ± 0.79% w/w for AE-5, whereas the formaldehyde route reached a maximum of 15.60 ± 0.62% w/w for AF-12; statistical analysis confirmed significant differences among extraction conditions (ANOVA, p < 0.05). Despite its lower yield, the formaldehyde route produced alginate with higher intrinsic viscosity (2.13 dL/g) and viscosity-average molecular weight (1.00 × 105 g/mol) than the ethanol-derived sample (1.33 dL/g and 0.62 × 105 g/mol), indicating better preservation of polymer chain length. ¹H NMR analysis showed that AE-5 had higher guluronic acid content (F_G = 0.60), lower M/G ratio (0.67), and higher G-block fraction (F_GG = 0.54), favoring Ca²⁺-mediated junction zone formation. Consequently, AE-5-derived hydrogels exhibited the highest storage modulus at 1 Hz (G′ = 23,650 Pa), compared with AF-12-derived hydrogels (13,160 Pa) and the commercial reference (14,480 Pa). However, visual inspection and swelling analysis showed that the higher small-amplitude stiffness of AE-5 did not translate into superior macroscopic integrity; these hydrogels showed greater fragmentation during handling and higher long-term swelling. In contrast, AF-12-derived hydrogels showed lower stiffness but better apparent cohesion and a more restricted swelling profile, consistent with enhanced long-range network connectivity derived from higher molecular weight. FTIR confirmed preservation of the characteristic functional groups of sodium alginate, whereas XRD provided qualitative evidence of residual crystalline inorganic phases. Selected-metal analysis by MP-AES detected Cu in both extracted alginates, while As was detected but not quantified only in AF-12; Cd and Pb were not detected under the analytical conditions employed. Overall, the results establish a route-dependent structure-property relationship in which extraction conditions govern yield, chain preservation, block architecture, viscoelastic response, swelling behavior, and preliminary contaminant profile. These findings support beach-cast Sargassum as a promising source of research-grade sodium alginate, while emphasizing that further purification, expanded contaminant profiling, arsenic speciation, biological evaluation, and direct mechanical testing are required before any food, biomedical, pharmaceutical, or environmental application can be proposed. Full article

Rapid industrialization and global population growth have led to numerous environmental issues. Among these issues, water polluted with toxic heavy metal ions (HMIs) has become a serious problem. Of the various removal methods, adsorption is considered to be one of the most widely used for purifying wastewater due to its simple operation, high adsorption efficiency, low cost and broad applicability. Bio-based hydrogels are becoming increasingly popular for water purification due to the variety of fabrication and modification methods available. These hydrogels act as adsorption aggregators, increasing the local concentration of HMIs. Bio-based fluorescent hydrogels with fluorescent sensors could be further used to sensitively detect the HMIs, accompanied by an obvious fluorescence quenching. The non-radiative energy transfer between the fluorescent sensor and the adsorbed metal ions is responsible for the sensitive detection. In this review, the recent progress of bio-based fluorescent hydrogels for the adsorption and sensing of toxic HMIs is fully summarized. According to the natural hydrogel sources, the bio-based hydrogels, including cellulose-, chitosan-, alginate- and lignin-based hydrogels, are discussed separately. Finally, the challenges, suggestions and opportunities involved in developing novel bio-based fluorescent hydrogels for the adsorption and sensing of toxic HMIs are presented. Full article

Marine algae, microalgae, and Cyanophyceae emerge as sustainable and versatile sources of biomacromolecules for the fabrication of hydrogels with broad biomedical potential. Their phycocolloids, such as alginate, agar, carrageenan, ulvan, and extracellular polysaccharides (EPS), exhibit intrinsic biocompatibility, tunable gelation behavior, and bioactive sulfated structures that support cell viability, tissue regeneration, and therapeutic delivery. This review provides a comprehensive overview of hydrogel fabrication strategies, including physical, chemical, and hybrid crosslinking approaches, and highlights recent advances in composite systems incorporating proteins, glycosaminoglycans, and functional nanomaterials. Applications in skin repair, cartilage and bone regeneration, neural and cardiovascular engineering, and controlled drug delivery are examined, alongside the expanding role of marine-derived hydrogels as bioinks for 3D and 4D bioprinting. Despite their promise, challenges remain related to extract variability, purification complexity, mechanical limitations, and the need for standardized characterization. Future perspectives emphasize genetic engineering of algae and cyanobacteria, development of multifunctional hybrid hydrogels, sustainable large-scale production, and pathways toward clinical translation. Together, these insights position marine-derived hydrogels as next-generation biomaterials with significant potential for regenerative medicine and therapeutic innovation. Full article

Developing sustainable and molecularly selective adsorbents for heavy-metal removal remains a critical challenge in water purification. Herein, we report a green molecular-engineering approach for fabricating aza-crown ether functionalized sodium alginate aerogels (ACSA) capable of highly selective Cu²⁺ capture. The aerogels were synthesized via saccharide-ring oxidation, Cu²⁺-templated self-assembly, and reductive amination, enabling the covalent integration of aza-crown ether motifs within a hierarchically porous biopolymer matrix. Structural analyses (FTIR, ¹³C NMR, XPS, SEM, TGA) confirmed the in situ formation of macrocyclic N/O coordination sites. Owing to their interconnected porosity and chemically stable framework, ACSA exhibited rapid sorption kinetics following a pseudo-second-order model (R² = 0.999) and a Langmuir maximum adsorption capacity of 150.82 mg·g⁻¹. The material displayed remarkable Cu²⁺ selectivity over Zn²⁺, Cd²⁺, and Ni²⁺, arising from the precise alignment between Cu²⁺ ionic radius (0.73 Å) and crown-cavity dimensions, synergistic N/O chelation, and Jahn-Teller stabilization. Over four regeneration cycles, ACSA retained more than 80% of its original adsorption capacity, confirming excellent durability and reusability. This saccharide-ring modification strategy eliminates crown-ether leaching and weak anchoring, offering a scalable and environmentally benign route to bio-based adsorbents that combine molecular recognition with structural stability for efficient Cu²⁺ remediation and beyond. Full article

The integration of bioethanol into transportation fuels requires efficient purification methods to overcome the ethanol–water azeotrope, which cannot be separated by conventional distillation. Pervaporation has become an attractive alternative, offering high selectivity while minimising energy consumption. To further improve membrane performance, this study analyses sodium alginate-based hybrid membranes containing binary mixtures of chromite selenides with varying magnetic properties (ZnCr₂Se₄, CdCr₂Se₄, and CuCr₂Se₄). Pairwise combinations of these fillers were introduced to create complex magnetic structures that can influence polymer–filler interactions and molecular transport. Structural, magnetic, and functional characterisation showed that membrane properties were strongly dependent on the type and proportion of fillers. In particular, the CdCr₂Se₄ with CuCr₂Se₄ combination exhibited the most favourable balance between permeation flux and selectivity, achieving the highest parameters, including pervaporation separation index (PSI) reaching 747 kg·m⁻²·h⁻¹. This superior performance is attributed to the synergistic interaction of these two magnetic fillers, which enhances membrane selectivity while maintaining its integrity. This work presents a novel approach to membrane-based separation, advancing the development of energy-efficient, environmentally sustainable bioethanol purification technologies. Full article

The rapid development of industry has led to the discharge of large quantities of organic pollutants into water bodies, posing a significant threat to aquatic safety. It is imperative to develop efficient and environmentally friendly methods for the elimination of organic pollutants. The integration of hydrogel membranes with advanced oxidation processes (AOPs) for water purification has attracted considerable interest due to their high efficiency. However, conventional wet membrane materials stored in aqueous environments are more prone to swelling and leakage of loaded metal species. This limits its application in the degradation of organic pollutants. This study employs a vacuum drying strategy for wet hydrogels, incorporating molybdenum disulfide as a cocatalyst and Co²⁺ cross-linking within the alginate matrix, resulting in a dried MoS₂–cobalt alginate hydrogel membrane (D-MoS₂-CoAlg). The drying process of the D-MoS₂-CoAlg membrane not only significantly enhanced its mechanical strength and anti-swelling capacity but also effectively mitigated the leaching of Co²⁺. Throughout five consecutive cycles, the concentration of leached Co²⁺ remained below 0.032 mg/L. This enables the membrane to achieve a balance between reusability and environmental compatibility. Under the conditions of a drying time of 60 min, a peroxymonosulfate (PMS) dosage of 0.2 mmol/L, and an initial methylisothiazolinone (MIT) concentration of 20 mg/L, the D-MoS₂-CoAlg membrane exhibited exceptional catalytic performance, achieving a degradation rate of MIT as high as 92.14% within 5 min. The D-MoS₂-CoAlg membrane demonstrates high catalytic activity and good stability, showing promising potential for application in the field of organic wastewater treatment. Full article

In recent years, seaweed-derived polysaccharides have gained recognition as renewed potent bioactive compounds with significant antibacterial and antiviral properties. These polysaccharides include carrageenan, agar, agarose, and porphyran from red seaweed; fucoidan, laminarin, and alginate (alginic acid) from brown seaweed; and ulvan from green seaweed. Their diverse and complex structures, shaped by sulfation patterns, glycosidic linkages, and monosaccharide composition, contribute to their broad-spectrum biological activities, including antimicrobial, immunomodulatory, and prebiotic functions. This review explores the structural characteristics of these marine polysaccharides, reported in vitro and in vivo antimicrobial activities, and the mechanisms underlying their antibacterial and antiviral effects. Additionally, the extraction, purification methods, and commercial applications of these bioactive polysaccharides are discussed. By integrating recent advances and highlighting their multifunctionality, this review underscores the translational promise of seaweed-derived polysaccharides as sustainable, natural agents in the global fight against antimicrobial resistance and infectious diseases. Full article

Traditional water purification systems often rely on synthetic materials that pose environmental risks due to their non-biodegradability and the potential release of harmful substances. To address these concerns, natural polymer-based membranes are being developed as a sustainable and environmentally friendly alternative for water treatment due to their biodegradability, low toxicity, and chemical versatility. These materials are particularly suitable for removing a wide range of contaminants due to their high selectivity and water permeability. Despite their benefits, challenges such as improving mechanical strength, durability, and resistance to fouling persist. Ongoing research continues to optimize the performance of electrospun membranes to meet modern water treatment demands. For this purpose, crosslinking via thermal initiators azobisisobutyronitrile (AIBN) and 2,2’-azobis(2-amidinopropane)dihydrochloride (V50) and chemical crosslinking by glutaraldehyde (GA) vapor have been studied for methacrylated chitosan and alginate. In addition, biocharcoal has been introduced into the membranes to enhance their functional properties. The development of natural polymer-based membranes combined with biocharcoal presents a promising and scalable solution for sustainable water purification, playing a crucial role in reducing pollution and preserving vital water resources for future generations. In this study, we demonstrate that the crosslinking effect plays a key role in maintaining the stability of alginate-based membranes in an aqueous environment while enhancing their adsorption capacity for methylene blue dye, making them promising for water purification applications. Full article