Persistent free radicals (PFR) in carbonized particles may play a role in degradation of environmental compounds. The influence of PFR is evaluated in various carbonized particles on their radical scavenging efficiency upon the common radical indicator 2-2-diphenyl-1-picrylhydrazyl (DPPH). Carbonized particles are derived by hydrothermal carbonization of glucose (C-W) or glucose and urea (NC-W) and ionothermal carbonization of glucose and urea ionic liquid (IL) (NC-IL). The carbonized materials contain OH/COOH, C=C, and C-O functionalities. The addition of urea introduces NH/NH2 functionalities. The content of polar surface groups is lower in IL-processed NC-IL. The scavenging ability, measured as DPPH UV-vis absorption decline, increases with concentration and time for all particles, while the efficiency changes are in the order of C-W > NC-W > NC-IL. Electron paramagnetic resonance analysis reveals similar radical concentration in all carbonized materials studied. The difference in efficiency is, thus, not directly related to the PFR concentration but rather to the type of PFR, surface functionalities and/or scavenging mechanism. According to the g-values, radicals in these particles are carbon-centered. The minor variation in g-values suggests interactions between the radicals and their environmental functional groups. This provides insights into the influence of PFR in carbonized materials on their radical scavenging efficiency.

Abstract A fungal biorefinery is presented to valorize food waste to fungal monofilaments with tunable properties for different textile applications. Rhizopus delemar is successfully grown on bread waste and the fibrous cell wall is isolated. A spinnable hydrogel is produced from cell wall by protonation of amino groups of chitosan followed by homogenization and concentration. Fungal hydrogel is wet spun to form fungal monofilaments which underwent post‐treatments to tune the properties. The highest tensile strength of untreated monofilaments is 65 MPa (and 4% elongation at break). The overall highest tensile strength of 140.9 MPa, is achieved by water post‐treatment. Moreover, post‐treatment with 3% glycerol resulted in the highest elongation % at break, i.e., 14%. The uniformity of the monofilaments also increased after the post‐treatments. The obtained monofilaments are compared with commercial fibers using Ashby's plots and potential applications are discussed. The wet spun monofilaments are located in the category of natural fibers in Ashby's plots. After water and glycerol treatments, the properties shifted toward metals and elastomers, respectively. The compatibility of the monofilaments with human skin cells is supported by a biocompatibility assay. These findings demonstrate fungal monofilaments with tunable properties fitting a wide range of sustainable textiles applications.

Pyrolysis of rice husk (RH), alkali-treated cellulose-rich rice husk (RHC), chemically modified RHC (RHCM) and RH-biocomposites by thermogravimetric analysis was carried out to determine combustion and kinetic parameters at three different heating rates of 20, 40 and 50 °C min −1 . Combustion performance was analyzed from results of ignition temperature, burnout temperature, combustion rates, flammability index and combustion characteristic index. Increase in heating rate from 20 to 40 and further to 50 °C min −1 increased the onset of degradation, burnout and peak temperatures as observed by curve shifts to the right. Maximum combustion rates were around 0.57–0.59% min −1 , 1.03% min −1 and 0.63–0.69% min −1 for RH, RHC and RHCM, respectively. For the RH-biocomposites, the maximum combustion rates were in a 0.76–0.97% min −1 range. Their average pre-exponential factors using KAS method were in the 2.24E-03–8.07E-03 range, respectively, while those for OFW method were in the 7.75E + 04–4.55E + 06 range, respectively. Average activation energies of RH-biocomposites were in the 41.0–58.2 kJ mol −1 and 48.3–67.7 kJ mol −1 ranges for KAS and OFW methods, respectively. The data were well fitting with coefficient of determination ( R 2 ) values close to 1. Average Δ G value ranges for RH-biocomposites ranged between 148.2 and 161.7 kJ mol −1 . The low-energy barrier (≤ 5.4 kJ mol −1 ) between activation energy and enthalpy changes indicated that reaction initiation occurs easily.

The fungus Rhizopus delemar was grown on bread waste in a submerged cultivation process and wet-laid into films. Alkali or enzyme treatments were used to isolate the fungal cell wall. A heat treatment was also applied to deactivate biological activity of the fungus. Homogenization of fungal biomass was done by an iterative ultrafine grinding process. Finally, the biomass was cast into films by a wet-laid process. Ultrafine grinding resulted in densification of the films. Fungal films showed tensile strengths of up to 18.1 MPa, a Young’s modulus of 2.3 GPa and a strain at break of 1.4%. Highest tensile strength was achieved using alkali treatment, with SEM analysis showing a dense and highly organized structure. In contrast, less organized structures were obtained using enzymatic or heat treatments. A cell viability assay and fluorescent staining confirmed the biocompatibility of the films. A promising route for food waste valorization to sustainable fungal wet-laid films was established.

Here, cell wall of a zygomycete fungus, Rhizopus delemar, grown on bread waste was wet spun into monofilaments. Using the whole cell wall material omits the common chitosan isolation and purification steps and leads to higher material utilization. The fungal cell wall contained 36.9% and 19.7% chitosan and chitin, respectively. Solid state NMR of the fungal cell wall material confirmed the presence of chitosan, chitin, and other carbohydrates. Hydrogels were prepared by ultrafine grinding of the cell wall, followed by addition of lactic acid to protonate the amino groups of chitosan, and subsequently wet spun into monofilaments. The monofilament inhibited the growth of Bacillus megaterium (Gram+ bacterium) and Escherichia coli (Gram- bacterium) significantly (92.2% and 99.7% respectively). Cytotoxicity was evaluated using an in vitro assay with human dermal fibroblasts, indicating no toxic inducement from exposure of the monofilaments. The antimicrobial and biocompatible fungal monofilaments, open new avenues for sustainable biomedical textiles from abundant food waste.

Food waste and fashion pollution are two of the most prominent global environmental issues. To alleviate the problems associated with food waste, while simultaneously contributing to sustainable fashion, the feasibility of making an alternative textile material with leather-like properties from fungal biomass cultivated on bread waste was investigated. The filamentous fungus, Rhizopus delemar, was successfully grown on waste bread in a submerged cultivation process, and fungal biomass was treated with vegetable tannin of chestnut wood. NMR and FTIR confirmed interactions between tannin and fungal biomass, while OM, SEM and AFM visualised the changes in the hyphae upon the tannin treatment. Thermal stability was assessed using TGA analysis. The wet-laid technique commonly utilised for paper-making was used to prepare sheets of hyphae. Some of the sheets were treated with glycerol and/or a biobased binder as post-treatment. Overall, three of the produced materials exhibited leather-like properties comparable to that of natural leather. Sheets from untreated biomass with only glycerol post-treatment showed a tensile strength of 7.7 MPa and an elongation at break of 5%. Whereas sheets from untreated biomass and tannin treated biomass with both glycerol and binder treatments led to tensile strengths of 7.1 MPa and 6.9 MPa, and the elongation at break of 12% and 17%, respectively. The enhancement of hydrophobicity after the binder treatment, helped to preserve the absorbed glycerol within the sheet and thereby the flexibility was retained when in contact with moisture. These findings demonstrate that bread waste-derived fungal sheets have great potential as environmentally friendly materials with leather-like properties.

•A 1,3-dioxolan-4-one-based monomer bearing a double functionality was successfully synthesized.•The monomer was employed for the synthesis of PLA-PS graft copolymers.•The copolymers were used for the preparation of PLA blends, pointing out a self-assembly behavior directed by the matrix.•Blends were characterized in their thermal, morphological and mechanical properties.•The chemical recyclability of the copolymer was demonstrated.•The compatibilizing effect of the copolymer in PLA/PS blends was pointed out by means of rheological analyses.

Chemical modification of biopolymers, before use in thermoplastic applications, can reduce the susceptibility to open environment degradation. We demonstrate carbon dots (CDs) as green photocatalytic triggers that can render the common cellulose derivative, cellulose acetate (CA), degradable under open environment relevant conditions. CD-modified cellulose acetate (CA + CD) films were subjected to UV-A irradiation in air and simulated sea water, and the degradation process was mapped by multiple spectroscopic, chromatographic, and microscopy techniques. The addition of CDs effectively catalyzed the deacetylation reaction, the bottleneck preventing biodegradation of CA. The photocatalytically activated degradation process led to significant weight loss, release of small molecules, and regeneration of cellulose fibers. The weight loss of CA + CD after 30 days of UV-A irradiation in air or simulated sea water was 53 and 43%, respectively, while the corresponding values for plain CA films were 12 and 4%. At the same time the weight average molar mass of CA + CD decreased from 62,000 to 11,000 g/mol and 15,000 g/mol during UV-A irradiation in air and simulated sea water, respectively, and the degree of substitution (DS) decreased from 2.2 to 1.6 both in air and in water. The aging in water alone did not affect the weight average molar mass, but the DS was decreased to 1.9. Control experiments confirmed the generation of hydrogen peroxide when aqueous CD dispersion was subjected to UV-A irradiation, indicating a free radical mechanism. These results are promising for the development of products, such as mulching films, with photocatalytically triggered environmental degradation processes.

Adipic acid was evaluated as a novel solvent for wet spinning of chitosan fibers. A solvent with two carboxyl groups could act as a physical crosslinker between the chitosan chains, resulting in improved properties of the fibers. The performance of adipic acid was compared with conventional solvents, i.e., lactic, citric, and acetic acids. Chitosan solutions were injected into a coagulation bath to form monofilaments. Sodium hydroxide (NaOH) and its mixture with ethanol (EtOH) were used as coagulation agents. Scanning electron microscopy confirmed the formation of uniform chitosan monofilaments with an even surface when using adipic acid as solvent. These monofilaments generally showed higher mechanical strength compared to that of monofilaments produced using conventional solvents. The highest Young’s modulus, 4.45 GPa, was recorded for adipic acid monofilaments coagulated in NaOH-EtOH. This monofilament also had a high tensile strength of 147.9 MPa. Furthermore, taking advantage of chitosan insolubility in sulfuric acid (H2SO4) at room temperature, chitosan fibers were successfully formed upon coagulation in H2SO4-EtOH. The dewatering of fibers using EtOH before drying resulted in a larger fiber diameter and lower mechanical strength. Adipic acid fibers made without dehydration illustrated 18% (for NaOH), 46% (for NaOH-EtOH), and 91% (for H2SO4-EtOH) higher tensile strength compared to those made with dehydration.

The cell wall of a zygomycetes fungus was successfully wet spun into monofilament yarns and demonstrated as a novel resource for production of sustainable textiles. Furthermore, the fungus could be cultivated on bread waste, an abundant food waste with large negative environmental impact if not further utilized. Rhizopus delemar was first cultivated in bread waste in a bubble column bioreactor. The fungal cell wall collected through alkali treatment of fungal biomass contained 36 and 23% glucosamine and N-acetyl glucosamine representing chitosan and chitin in the cell wall, respectively. The amino groups of chitosan were protonated by utilizing acetic or lactic acid. This resulted in the formation of a uniform hydrogel of fungal microfibers. The obtained hydrogel was wet spun into an ethanol coagulation bath to form an aggregated monofilament, which was finally dried. SEM images confirmed the alignment of fungal microfibers along the monofilament axis. The wet spun monofilaments had tensile strengths up to 69.5 MPa and Young's modulus of 4.97 GPa. This work demonstrates an environmentally benign procedure to fabricate renewable fibers from fungal cell wall cultivated on abundant food waste, which opens a window to creation of sustainable fungal textiles. (C) 2021 The Authors. Published by Elsevier B.V.

To investigate whether contact lenses used after surgery for congenital cataracts act as a depot for dexamethasone, which would allow the prescribed amount of drops to be reduced, and to examine whether the preservative benzalkonium chloride accumulates in the contact lens matrix, which would suggest a need for more frequent replacements.

Frequent oil spill accidents and the massive discharge of industrial oily sewage have destroyed the ecological balance and threatened marine life. Graphene (G) and graphene oxide (GO) have emerged as important materials in the field of oil/water separation because of their remarkable physicochemical properties including high specific surface area, low density, high porosity and tailorable surface functionality. To take full advantage of G and GO, their incorporation with polymers to build functional G/polymer and GO/polymer composites has recently gained increasing popularity because of their improved oil clean-up capability, outstanding mechanical performance, relatively low cost and adjustable surface chemical composition. Tremendous efforts have contributed to the development of G/polymer and GO/polymer composite oil clean-up sorbents and filtration membranes in 3D structural forms such as aerogels, foams, sponges and membranes. In this review, a comprehensive picture from the basic theory of the surface wettability to the recent advances in G/polymer and GO/polymer composite oil clean-up sorbents and filtration membranes are highlighted. The strategies for oil recovery and regeneration of the sorbents are also summarized. Current challenges and future research directions in this topic are provided, aimed at providing new perspectives for in-depth exploration in this field.

Carbon dots (CDs), a novel family of multifunctional carbon-nanomaterials, has the potential to revolutionize several important fields supporting the transformation to sustainable bioeconomy. CDs are characterized by attractive properties such as tunable optoelectronic and fluorescence properties, low toxicity, good biocompatibility, bioactivity and superior water solubility. Diverse methods and precursors have been applied for the synthesis of CDs. The possibility to scale-up the synthesis of CDs by employing Green Chemistry principles is a current research hotspot and a prerequisite for large-scale production and applications. Incorporation of CDs into polymer matrices, is another emerging research area with wide potential application range. This approach endows additional desirable functions and enables easy handling and reuse. This review summarizes recent progress regarding the green synthesis of CDs, the fundamental strategies for the construction of CD/polymer nanocomposites and the state-of-art applications of the CD/polymer nanocomposites in the realm of energy storage, environment and biomedicine. Finally, the outlook including challenges and future potential of CDs and CD/polymer composites are discussed.

Hydrothermally carbonized cellulose and its further modifica-tions are intriguing materials for a wide range of potential ap-plications. Hydrothermal carbonization is a sustainable process for converting biopolymers or other biomass sources into carbonaceous materials under mild conditions in water and at relatively low temperatures. This review presents the latest progress in modification and utilization of hydrothermally carbonized cellulose and related materials in environmental, biomedical, and energy applications. Further applications presented include evaluation of cellulose-derived carbon spheres or carbon dots as catalysts, antibacterial materials, flame retardants, and functional fillers in bioplastic composites. The wide range of applications highlights the great potential and multifunctionality of hydrothermally carbonized cellulose and its derivatives. The field is expected to further expand and increase in importance as we move toward circular bioeconomy.

Thermoplastic “all-cellulose” composites were synthesized by covalent functionalization of cellulose acetate (CA) with oxidized carbonized cellulose (OCC). The OCC were manufactured via microwave-assisted hydrothermal carbonization (HTC) of cellulose followed by oxidation and dialysis. The OCC were of micrometer-size, had plane morphology and contained a variety of oxygen functionalities, enabling transformation into acyl chlorinated OCC under moderate reaction conditions. The synthesis of OCC-modified CA composites and neat CA were performed in the recyclable ionic liquid 1-allyl-3-methylimidazolium chloride. The degree of acetylation and amount of OCC were varied to establish their influence on thermal and physical properties of the composites. The OCC-modified CA composites displayed a notably enhanced film-forming ability, which led to improved optical and mechanical properties compared to neat CA. In addition, it was shown that OCC-modified CA composites can be synthesized from waste products, such as paper tissues. The OCC-modification was demonstrated to be a promising route to transparent and strong thermoplastic “all-cellulose” composites with moderate flexibility.

Cationized cellulose filters with coating of oxidized carbonized cellulose (OCC) were successfully fabricated. The OCC-coated filter was demonstrated as a combined surface for adsorption of environmental contaminants and their detection on the filter by surface-assisted desorption ionization-mass spectrometry (SALDI-MS). The cellulose filters were cationized by utilizing 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHTAC) and sodium hydroxide. It was shown that the degree of substitution increased with the CHTAC feed. OCC, synthesized by hydrothermal carbonization of cellulose with subsequent oxidation and dialysis, was attached onto the cationized filters by electrostatic interactions. The filters adsorbed the model contaminant methylene blue (MB) from aqueous solution, and the MB could subsequently be detected on the filter surfaces by SALDI-MS as [M](+) adduct. The OCC coating further improved the relative peak intensity of [M](+) with little background interferences. This work indicates great potential for the OCC-coated filters as a combined surface for rapid monitoring of environmental contaminants.

Elongated carbon structures, here denoted as carbon flakes (CF), are revealed after microwave-assisted hydrothermal carbonization of sodium lignosulfonate. The morphology of formed CF is investigated by transmission electron microscopy and atomic force microscopy. Interestingly, a wide range of length distributions (between 100 and 700 nm) and a relatively constant aspect ratio and thickness are observed, indicating structures clearly different from the carbon spheres commonly formed during hydrothermal carbonization of lignocellulosic biomass. Moreover, X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy provide further information of the chemical structure, which consist mainly of nanographitic domains with a high degree of defects such as oxygenated functional groups, hybridized sp3 carbon, and aliphatic side chains. Furthermore, new insights into the formation mechanisms are uncovered and the formation is speculated to proceed through the combined effect of microwave irradiation and a heterogeneous solid-solid conversion. The formed CF are anticipated as highly interesting products for a variety of material applications.

The advance of miniaturized and low-power electronics has a striking impact on the development of energy storage devices with constantly tougher constraints in terms of form factor and performance. Microsupercapacitors (MSCs) are considered a potential solution to this problem, thanks to their compact device structure. Great efforts have been made to maximize their performance with new materials like graphene and to minimize their production cost with scalable fabrication processes. In this regard, we developed a full inkjet printing process for the production of all-graphene microsupercapacitors with electrodes based on electrochemically exfoliated graphene and an ultrathin solid-state electrolyte based on nano-graphene oxide. The devices exploit the high ionic conductivity of nano-graphene oxide coupled with the high electrical conductivity of graphene films, yielding areal capacitances of up to 313 μF cm-2 at 5 mV s-1 and high power densities of up to ∼4 mW cm-3 with an overall device thickness of only ∼1 μm.

Carbon spheres (CS) are interesting materials for antibacterial applications. Herein, CS are produced by a green process utilizing microwave-assisted hydrothermal treatment of cellulose. The CS are then postmodified in acidic and basic solutions to evaluate the influence of different functionalities on antibacterial properties. CS contain OH/COOH, C-C, and C-O functionalities, while O-CS produced by acid treatment of CS have additional COOH, and NH/NH2 groups, resulting in carbon spheres with negatively and positively charged groups in dispersion. Treatment with base (Na-CS) removes low molecular weight species with oxygen and results in carbon spheres with the highest C/O ratio. CS, O-CS, and Na-CS have nonporous morphology and are in micro/nanometer sizes, although, smaller sized spheres, hollow spheres, and fragments are also attained in the case of O-CS. O-CS show antibacterial activity toward both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Pseudomonas aeruginosa (P. aeruginosa). The minimum inhibitory concentration is 200 and 400 mu g mL(-1) for S. aureus and P. aeruginosa, respectively, and is achieved only after 3 h of incubation. Neither CS nor Na-CS exhibit antibacterial activity. The antibacterial activity is suggested to originate from electrostatic interactions between O-CS and the bacteria.

Utilizing renewable recourses and waste recycling are necessary for reaching a circular resource society. The concept of this thesis was to set up a sustainable recycling route, suitable even for l ...