Improving konjac glucomannan-based aerogels filtration properties by combining aerogel pieces in series with different pore size distributions

Konjac glucomannan-based foams incorporating cellulose phase change microcapsules for efficient thermal energy regulation

Biomass foam with porous structure has broad application prospects in thermal energy management. However, traditional foams can only passively insulate heat, unable to effectively store thermal energy and prolong the insulation time. In this work, microcapsules rich in paraffin were prepared using the Pickering emulsion template method with phosphorylated cellulose nanocrystals (CNC) as an emulsifier. Phase change microcapsules were combined with konjac glucomannan (KGM) foam to prepare thermal energy management materials with excellent thermal insulation and storage properties. The synergistic interaction between CNC and KGM molecules could form the hydrogen bond cross-linking network to further improve the water resistance and mechanical properties of foams. The encapsulation of CNC microcapsules and the capillary action of KGM foam could effectively inhibit paraffin leakage in the KGM/CNC/paraffin (KCP) foams. Moreover, the enthalpy of melting and crystallization of KCP-8 foam was 144.9 J/g and 141.3 J/g, respectively. The thermal conductivity and infrared thermal imaging results showed that KCP-8 foams exhibited excellent thermal insulation and heat storage properties. This study provides ideas for the design and preparation of porous foams with thermal regulation properties, which has great potential in the field of intelligent textile and building energy conservation.

Konjac glucomannan foams integrated with bilayer phase change microcapsules for efficient heat storage and thermal insulation

The traditional foams can only block heat loss, and cannot effectively store and release heat energy on demand to extend the insulation time. In this work, the paraffin-rich monolayer microcapsules were prepared using negatively charged phosphorylated cellulose nanofibers (CNF) as the emulsifier of Pickering emulsion. The positive chitosan was assembled on the surface of the monolayer microcapsules through an electrostatic layer-by-layer self-assembly method to prepare the bilayer microcapsules. Konjac glucomannan (KGM) was used as the dispersive medium of bilayer microcapsules and the gel skeleton to prepare phase change foam through freeze-drying. The foams exhibited excellent water resistance, mechanical properties, and thermal stability. The double-shell structure of chitosan/CNF microcapsules and the capillary action of KGM foam could effectively inhibit paraffin leakage. Moreover, the paraffin content of KCCP-4 foam was as high as 72.7 %, and the enthalpy of melting and crystallization were as high as 149 J/g and 146 J/g, respectively. The thermal conductivity and infrared thermal imaging results demonstrated that the KCCP-4 foam had excellent thermal insulation and energy storage properties. This study provides a simple and effective design strategy for the application of thermal insulation and energy storage foams in smart textiles.

An ammonia-responsive aerogel-type colorimetric sensor for non-destructive monitoring of shrimp freshness

The colorimetric sensor for volatile amines (VA) detection can realize non-destructive monitoring of shrimp quality. However, its sensing performance still needs to be improved. In this study, we proposed an aerogel-type colorimetric sensor to improve VA sensing performance and realize early detection of shrimp spoilage. The sensor was composed of konjac glucomannan-based aerogel prepared by sol-gel and freeze-drying, and pH-responsive dyes (neutral red) which were adsorbed on the aerogel surface. The sensor could show color change from pink to orange under the exposure of NH3, a marker of spoiled shrimp and the Euclidean Distance (ΔE) of the sensor was positively correlated with NH3 concentration. Due the three-dimensional network of the aerogel and its adsorption performance, the sensitivity of the aerogel-type sensor in NH3 detection was ∼6 times higher and the maximum ΔE was ∼1.5 times higher compared with the film-type sensor. It also showed stable sensing performance under various environment and was further successfully used in shrimp freshness monitoring. It was found that ΔE higher than 23.88 indicated the spoilage of shrimp. The above results provided a general approach for the designing of high-performance colorimetric sensor for real-time and non-destructive monitoring of shrimp freshness.

Borax Cross-Linked Acrylamide-Grafted Starch Self-Healing Hydrogels

The biocompatibility and renewability of starch-based hydrogels have made them popular for applications across various sectors. Their tendency to incur damage after repeated use limits their effectiveness in practical applications. Improving the mechanical properties and self-healing of hydrogels simultaneously remains a challenge. This study introduces a new self-healing hydrogel, synthesized by grafting acrylamide onto starch using ceric ammonium nitrate (CAN) as an initiator, followed by borax cross-linking. We systematically examined how the starch-to-monomer ratio, borax concentration, and CAN concentration impact the grafting reactions and overall performance of the hydrogels. The addition of borax significantly reinforced the strength of the hydrogel; the maximum storage modulus increased by 1.8 times. Thanks to dynamic borate ester and hydrogen bonding, the hydrogel demonstrated remarkable recovery properties and responsiveness to temperature. We expect that the present research could broaden the application of starch-based hydrogels in agriculture, sensors, and wastewater treatment.

Bioaerogels from biomass waste: An alternative sustainable approach for wastewater treatment

The generation of municipal solid waste is projected to increase from 2.1 billion tonnes in 2023 to 3.8 billion tonnes by 2050. In 2020, the direct global cost of managing this waste was approximately USD 252 billion. When considering additional hidden costs-such as those arising from pollution, adverse health effects, and climate change due to inadequate waste disposal-the total cost escalates to USD 361 billion. Without significant improvements in waste management practices, this figure could nearly double by 2050, reaching an estimated USD 640.3 billion annually. Among municipal solid waste, biowaste accounts for roughly 44 % of the global municipal solid waste, translating to about 840 million tonnes annually. They are widely accessible and economical, offering a cost-effective alternative to traditional treatment materials. Transforming biomass waste into carbon-based materials (e.g., bioaerogels) is a sustainable practice that reduces waste and repurposes it for environmental remediation. This approach not only decreases the volume of waste directed to landfills and mitigates harmful greenhouse gas emissions from decomposition but also aligns with the principles of a circular economy. Furthermore, it supports sustainable development goals by addressing issues such as water scarcity and pollution while promoting waste valorization and resource efficiency. The unique properties of bioaerogels-including their porosity, multi-layered structure, and chemical adaptability-make them highly effective for the remediation of different water pollutants from aquatic bodies. This review article comprehensively delves into multifaceted wastewater remediation strategies -based bioaerogels such as coagulation and flocculation, advanced oxidation processes, membrane filtration, catalytic processes, water disinfection, Oil-water separation, biodegradation, and adsorption. Additionally, it examines different mechanisms of interaction such as surface adsorption, electrostatic interaction, van der Waals forces, ion exchange, surface precipitation, complexation, pore-filling, hydrophobic interactions, and π-π stacking. Moreover, it conducts an integrated techno-economic evaluation to assess their feasibility in wastewater treatment. By valorizing biomass waste, a closed-loop system can be established, where waste is transformed into valuable bioaerogels. This approach not only addresses challenges related to effluent pollution but also generates economic, environmental, and social benefits. Ultimately, the review underscores the transformative potential of bioaerogels in wastewater treatment, emphasizing their crucial role in supporting long-term environmental goals and advancing the principles of resource circularity.

Konjac glucomannan-based composite materials: Construction, biomedical applications, and prospects

Konjac glucomannan (KGM) as an emerging natural polymer has attracted increasing interests owing to its film-forming properties, excellent gelation, non-toxic characteristics, strong adhesion, good biocompatibility, and easy biodegradability. Benefiting from these superior performances, KGM has been widely applied in the construction of multiple composite materials to further improve their intrinsic performances (e.g., mechanical strength and properties). Up to now, KGM-based composite materials have obtained widespread applications in diverse fields, especially in the field of biomedical. Therefore, a timely review of relevant research progresses is important for promoting the development of KGM-based composite materials. Innovatively, firstly, this review briefly introduced the structure properties and functions of KGMs based on the unique perspective of the biomedical field. Then, the latest advances on the preparation and properties of KGM-based composite materials (i.e., gels, microspheres, films, nanofibers, nanoparticles, etc.) were comprehensively summarized. Finally, the promising applications of KGM-based composite materials in the field of biomedical are comprehensively summarized and discussed, involving drug delivery, wound healing, tissue engineering, antibacterial, tumor treatment, etc. Impressively, the remaining challenges and opportunities in this promising field were put forward. This review can provide a reference for guiding and promoting the design and biomedical applications of KGM-based composites.

Superior flame retardancy, thermal insulation, and mechanical properties of konjac glucomannan/sodium alginate biomass aerogel modified by supramolecular assembled phytic acid-melamine nanosheet

The development of biomass-based eco-friendly aerogel with superior flame retardancy, thermal insulation, and mechanical properties at the same time has long been a tough challenge. In this study, the polysaccharide-based aerogels composed of konjac glucomannan, sodium alginate, and supramolecular assembled melamine phytate (MPA) nanosheets were successfully fabricated through the freeze-drying method. Owing to the excellent charcoal-forming and non-combustible gas-releasing effect of MPA nanosheets, the thermal stability and flame retardancy properties of the aerogels were both significantly enhanced, with the highest limiting oxygen index value reaching 42.4 %. Meanwhile, appropriate MPA embedded in the pore walls greatly enhanced the compressive strength of the aerogel (364.9 kPa) and can withstand >7100 times its weight without visual deformation. Moreover, the thermal insulation effect was quite attractive with a thermal conductivity of 0.0385-0.0420 W/mK. The present work provided an environmentally friendly method for the fabrication of multifunctional sustainable fire-resistant aerogels, which showed promising prospects in the future.

Effects of the Amylose/Amylopectin Ratio of Starch on Borax-Crosslinked Hydrogels

Herein, we simultaneously prepared borax-crosslinked starch-based hydrogels with enhanced mechanical properties and self-healing ability via a simple one-pot method. The focus of this work is to study the effects of the amylose/amylopectin ratio of starch on the grafting reactions and the performance of the resulting borax-crosslinked hydrogels. An increase in the amylose/ amylopectin ratio increased the gel fraction and grafting ratio but decreased the swelling ratio and pore diameter. Compared with hydrogels prepared from low-amylose starches, hydrogels prepared from high-amylose starches showed pronouncedly increased network strength, and the maximum storage modulus increased by 8.54 times because unbranched amylose offered more hydroxyl groups to form dynamic borate ester bonds with borate ions and intermolecular hydrogen bonds, leading to an enhanced crosslink density. In addition, all the hydrogels exhibited a uniformly interconnected network structure. Furthermore, owing to the dynamic borate ester bonds and hydrogen bonds, the hydrogel exhibited excellent recovery behavior under continuous step strain, and it also showed thermal responsiveness.

Hydrophobic Silk Fibroin-Agarose Composite Aerogel Fibers with Elasticity for Thermal Insulation Applications

Aerogel fibers, characterized by their ultra-low density and ultra-low thermal conductivity, are an ideal candidate for personal thermal management as they hold the potential to effectively reduce the energy consumption of room heating and significantly contribute to energy conservation. However, most aerogel fibers have weak mechanical properties or require complex manufacturing processes. In this study, simple continuous silk fibroin-agarose composite aerogel fibers (SCAFs) were prepared by mixing agarose with silk fibroin through wet spinning and rapid gelation, followed by solvent replacement and supercritical carbon dioxide treatment. Among them, the rapid gelation of the SCAFs was achieved using agarose physical methods with heat-reversible gel properties, simplifying the preparation process. Hydrophobic silk fibroin-agarose composite aerogel fibers (HSCAFs) were prepared using a simple chemical vapor deposition (CVD) method. After CVD, the HSCAFs' gel skeletons were uniformly coated with a silica layer containing methyl groups, endowing them with outstanding radial elasticity. Moreover, the HSCAFs exhibited low density (≤0.153 g/cm3), a large specific surface area (≥254.0 m2/g), high porosity (91.1-94.7%), and excellent hydrophobicity (a water contact angle of 136.8°). More importantly, they showed excellent thermal insulation performance in low-temperature (-60 °C) or high-temperature (140 °C) environments. The designed HSCAFs may provide a new approach for the preparation of high-performance aerogel fibers for personal thermal management.

Study on the Influence of the Preparation Method of Konjac Glucomannan-Silica Aerogels on the Microstructure, Thermal Insulation, and Flame-Retardant Properties

Natural polysaccharides with high viscosity, good thermal stability, and biocompatibility can improve the mechanical properties of inorganic silica aerogels and enhance their application safety. However, the effects of the preparation methods of polysaccharide-silica aerogels on their microstructure and application properties have not been systematically studied. To better investigate the effect of the microstructure on the properties of aerogel materials, two aerogels with different structures were prepared using Konjac glucomannan (KGM) and tetraethoxysilane (TEOS) via physical blending (KTB) and co-precursor methods (KTC), respectively. The structural differences between the KTB and KTC aerogels were characterized, and the thermal insulation and fire-retardant properties were further investigated. The compressive strength of the KTC aerogels with a cross-linked interpenetrating network (IPN) structure was three times higher than that of the KTB aerogels, while their thermal conductivity was 1/3 of that of the KTB aerogels. The maximum limiting oxygen index (LOI) of the KTC aerogels was 1.4 times, the low peak heat release rate (PHRR) was reduced by 61.45%, and the lowest total heat release (THR) was reduced by 41.35% compared with the KTB aerogels. The results showed that the KTC aerogels with the IPN have better mechanical properties, thermal insulation, and fire-retardant properties than the simple physically blending KTB aerogels. This may be due to the stronger hydrogen-bonding interactions between KGM and silica molecules in the KTC aerogels under the unique forcing effect of the IPN, thus enhancing their structural stability and achieving complementary properties. This work will provide new ideas for the microstructure design of aerogels and the research of new thermal insulation and fire-retardant aerogels.

Divalent metal ion removal from simulated water using sustainable starch aerogels: Effect of crosslinking agent concentration and sorption conditions

This paper evaluates corn starch aerogels, studying different crosslinking agent (trisodium citrate) concentrations (1:1, 1:1.5, and 1:2) and sorption conditions (contact time, adsorbent weight, and initial concentration) regarding the potentially toxic elements (PTEs) [Cd(II) or Zn(II)] adsorption of the aqueous systems. Besides, other properties of aerogels, such as structural properties, specific surface area, and mechanical performance, were evaluated. For adsorption results, better values were observed in adsorption capacity and efficiency for the initial concentration of 100 ppm. In addition, an adsorption time of 12 h and an adsorbent weight of 3.0 g obtained better results due to the possible balance in this time and the high specific surface area available for Cd(II) adsorption. As for the type of adsorbent, the Aero 1:1.5 sample (intermediate crosslinking agent concentration) obtained better results, possibly due to the high porosity, smaller pore sizes, high pore density, and high specific surface area (198 m²·g^-1). In addition, hydroxyl groups in the starch aerogel removed Cd(II) ions with 30 % adsorption efficiency. Lastly, Aero 1:1.5 obtained a high mechanical strength at compression and a satisfactory compressive modulus. In contrast, starch aerogels did not absorb the Zn(II) ion.

Bioaerogels, the emerging technology for wastewater treatment: A comprehensive review on synthesis, properties and applications

Over the past decade use of aerogels has received much attention as an emerging technology for wastewater treatment. However, production of aerogels is not environment-friendly. Owing to its excellent properties such as porosity, three-dimensional structure, being amenable to chemical modifications, it is imperative to devise strategies for their improved production and use. Bioaerogels are non-toxic and most of their precursor compounds are biomass-derived. This review aims to present a comprehensive report on survey of existing literature published on the use of bioaerogels for removal of all major categories of water contaminants, namely, heavy metals, industrial dyes, oil, organic compounds and pharmaceuticals. It also gives critical analysis of the lacunae in the existing knowledge such as lack of studies on domestic sewage, emerging pollutants, toxicity of raw materials and adequate disposal of used adsorbents. Proposals of overcoming the limitations in the applicability of bioaerogels, like combining constructed wetlands with use of bioaerogels, among others have been discussed. In this review, emphasis has been given on production of bioaerogels, with an aim to underscore the potential of valorization of biomass waste to develop novel materials for wastewater treatment in an effort towards creating a circular and green economy.

Effect of ultrasound assisted konjac glucomannan treatment on properties of chicken plasma protein gelation

The effect of ultrasound assisted konjac glucomannan treatment on the properties of chicken plasma protein gelation was investigated in this study. There were four gelation groups as follows: untreated plasma protein gelation (Control), gelation added konjac glucomannan (KGG), gelation by ultrasound treatment alone (UG) and gelation added konjac glucomannan combined with ultrasound treatment (KGUG). The data showed that the gelation strength and water-holding capacity of the treated groups were significantly increased compared with those of Control. The strongest bonding water was present in KGUG, followed by KGG and UG in low-field nuclear magnetic resonance. The storage energy (G') and loss energy modulus (G″) of KGUG showed the largest rheological properties, and the G' value was higher than that of G″. Furthermore, the elastic and gelatinous properties of UG, KGG and KGUG played a dominant role in viscoelasticity. After konjac glucomannan addition, the particle size of KGG increased significantly. Compared with that of the Control and KGG, the average particle size of UG and KGUG decreased significantly after ultrasound treatment. The hydrophobicity and disulfide bonds mainly affected the formation of heat-induced gelation in these four groups. Furthermore, KGUG with the highest hydrophobicity and disulfide bonds revealed the best stability. Therefore, the gelation of chicken plasma protein by ultrasound assisted konjac glucomannan treatment had excellent gelling properties.

Microstructure, Thermal Conductivity, and Flame Retardancy of Konjac Glucomannan Based Aerogels

With abundant renewable resources and good biodegradability, bio-based aerogels are considered as promising insulating materials for replacing the conventional petroleum-based foam. In this study, konjac glucomannan (KGM)-based aerogels were prepared as thermal insulation materials via a convenient sol–gel and freeze-drying progress with different content of plant polysaccharides, proteins, and wheat straw. The morphology, thermal conductivity, and flame retardancy of KGM-based aerogels were determined. The KGM-based aerogels showed a uniform three-dimensional porous microstructure. The addition of wheat straw could significantly reduce the pore size of aerogels due to its special multi-cavity structure. KGM-based aerogels showed low densities (0.0234–0.0559 g/cm⁻³), low thermal conductivities (0.04573–0.05127 W/mK), low peak heat release rate (PHRR, 46.7–165.5 W/g), and low total heat release (THR, 5.7–16.2 kJ/g). Compared to the conventional expanded polystyrene (EPS) and polyurethane (PU) foam, the maximum limiting oxygen index (LOI) of KGM-based aerogels increased by 24.09% and 47.59%, the lowest PHRR decreased by 79.37% and 94.26%, and the lowest THR decreased by 76.54% and 89.25%, respectively. The results demonstrated that the KGM-based aerogels had better performance on flame retardancy than PU and EPS, indicating high potential applications as heat insulation in the green advanced engineering field.