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Although many studies have investigated the hydrothermal transformation of feedstock biomass, little is known about the stability of the compounds present in the process liquid after the carbonization process is completed. The physicochemical characteristics of hydrothermal carbonization (HTC) liquid products may change over storage time, diminishing the amount of desired products or producing unwanted contaminants. These changes may restrict the use of HTC liquid products. Here, we investigate the effect of storage temperature (20, 4, and −18 °C) and time (weeks 1–12) on structural and compositional changes of selected organic compounds and physicochemical characteristics of the process liquid from the HTC of digested cow manure. ANOVA showed that the storage time has a significant effect on the concentrations of almost all of the selected organic compounds, except acetic acid. Considerable changes in the composition of the process liquid took place at all studied temperatures, including deep freezing at −18 °C. Prominent is the polymerization of aromatic compounds with the formation of precipitates, which settle over time. This, in turn, influences the inorganic compounds present in the liquid phase by chelating or selectively adsorbing them. The implications of these results on the further processing of the process liquid for various applications are discussed.

Herein, we report of the use of reactive eutectic media from ammonium formate and monosaccharides to synthesize poly(hydroxyalkyl)pyrazines via microwave irradiation. This enabled unprecedented fast rates as well as better atom economy compared to previous methods. We investigated the influence of water on the reaction yield as well as the physical properties of the eutectic media and could thereby drastically reduce the viscosity, while preserving high reaction yields. The results were consistent for different monosaccharide, using fructose, glucose, rhamnose and fucose as reactants. Furthermore, the major reaction products were separated, chemically analyzed and tested on their antimicrobial activity via high-throughput screening.

Biopolymers arise as environmentally benign alternatives to bio-accumulating, fossil resource-based synthetic polymers for a variety of applications, many of which require self-standing films or membranes. Novel sustainable amine-functionalized cellulose nanocrystals (CNCs) form dense films with low porosity suitable for gas barriers. Due to their brittleness, pure CNC membranes are challenging to work with but represent an attractive support material for selectivity-inducing additives. Supported ionic liquid membranes (SILMs) are promising due to their tunable properties and good performance in gas separation. In this study, we investigate the possibilities to realize such applications by applying glucose and ionic liquids (ILs) as additives with different functions in CNC-based membranes. By the choice of the plasticizer, the gas permeation behavior of the flexible self-standing films can be tuned from impermeable, using glucose as an additive, to permeable by addition of the ILs 1,3-dibutylimidazolium acetate and 1,3-ditetrahydrofurfurylimidazolium acetate. Tunability is also observed through the choice of the CNC source in the form of an inversed selectivity of the gas pair N2/O2, which was traceable to the CNCs’ source-specific properties. The contributions of the matrix and additive were analyzed by comparing CNC to chitosan membranes and considering gas solubilities and diffusivities. The obtained results underline the diversity and tunability of bio-derived functional materials.AB - Biopolymers arise as environmentally benign alternatives to bio-accumulating, fossil resource-based synthetic polymers for a variety of applications, many of which require self-standing films or membranes. Novel sustainable amine-functionalized cellulose nanocrystals (CNCs) form dense films with low porosity suitable for gas barriers. Due to their brittleness, pure CNC membranes are challenging to work with but represent an attractive support material for selectivity-inducing additives. Supported ionic liquid membranes (SILMs) are promising due to their tunable properties and good performance in gas separation. In this study, we investigate the possibilities to realize such applications by applying glucose and ionic liquids (ILs) as additives with different functions in CNC-based membranes. By the choice of the plasticizer, the gas permeation behavior of the flexible self-standing films can be tuned from impermeable, using glucose as an additive, to permeable by addition of the ILs 1,3-dibutylimidazolium acetate and 1,3-ditetrahydrofurfurylimidazolium acetate. Tunability is also observed through the choice of the CNC source in the form of an inversed selectivity of the gas pair Nsub>2/O, which was traceable to the CNCs’ source-specific properties. The contributions of the matrix and additive were analyzed by comparing CNC to chitosan membranes and considering gas solubilities and diffusivities. The obtained results underline the diversity and tunability of bio-derived functional materials.

openaire: EC/H2020/788489/EU//BioELCell Lisään tiedoston kun VoR julkaistaan B. P., S. F. and M. A. gratefully acknowledge the Max Planck Society for financial support. B. P. would like to thank Branislav Jeriga for preparing some of the CNC samples. A. R. and O. R. acknowledge funding support by the Academy of Finland’s Biofuture 2025 program under project 2228357-4 (3D Manufacturing of Novel Biomaterials). O. J. R. is grateful for the support received from the ERC Advanced Grant Agreement No. 788489 (‘‘BioElCell’’), the Canada Excellence Research Chair initiative (CERC-2018-00006), and Canada Foundation for Innovation (Project number 38623). R. A. acknowledges funding from the FinnCERES GoGlobal mobility fund. This work made use of the facilities of Aalto University’s Nanomicroscopy Center. Open Access funding provided by the Max Planck Society Direct ink writing (DIW) of Pickering emulsions offers great potential for constructing on-demand objects. However, the rheological properties of fluid emulsions greatly undermines the shape fidelity and structural integrity of 3D-printed structures. We solve here these challenges and realize a new route towards complex constructs for actual deployment. A dynamic, supramolecular host-guest hydrogel based on poly(ethylene glycol) and α-cyclodextrin was synthesized in the continuous phase of cellulose nanocrystal-stabilized Pickering emulsions. The storage modulus of the obtained emulgels could reach up to ∼113 kPa, while being shear thinning and yielding precise printability. Diverse complex architectures were possible with high shape fidelity and structural integrity. The printed objects, for example a double-wall cylinder with 75 layers, demonstrated excellent dimensional stability (shrinkage of 7 ± 2% after freeze-drying). With the merits of a simple fabrication process and the high biocompatibility of all the components, the concept of dynamic supramolecular hydrogel-reinforced emulgels represent a potentially versatile route to construct new materials and structures VIA DIW for use in bioproducts and biomedical devices.

Herein, we analyzed the hydrothermal processes applied to four very different side stream biomasses (chestnut foliage, sugar beet pressing chips, pine bark and branches from park cleaning, bamboo cuts) and identified diverse soluble products depending on the starting pH of the reaction, covering mild to strong basic pH conditions. Despite the biological diversity of the starting products, hydrothermal disintegration of biomass results in a remarkable reduction of chemical diversity towards a controllable number of molecular products, and the well-resolved and rather simple NMR-spectra allow the assignment of the products to only a few families of compounds. It has been revealed that in comparison with the classical hydrothermal treatment, where mostly hydrochar is produced, molar excess of base shifts the hydrothermal treatment towards a humification process. A further increase of the base content causes destruction of the biomass into the more oxygenated homogeneous colloid and thus, for the first time, it can be assigned to the hydrothermal fulvication process. We discuss diverse valorization schemes depending on the biomass and conditions applied.

As tighter regulations on color in discharges to water bodies are more widely implemented worldwide, the demand for reliable inexpensive technologies for dye removal grows. In this study, the removal of the basic dye, methylene blue, by adsorption onto low-cost sodium alginate-kaolin beads was investigated to determine the effect of operating parameters (initial dye concentration, contact time, pH, adsorbent dosage, temperature, agitation speed) on dye removal efficiency. The composite beads and individual components were characterized by a number of analytical techniques. Three models were developed to describe the adsorption as a function of the operating parameters using regression analysis, and two powerful intelligent modeling techniques, genetic programming and artificial neural network (ANN). The ANN model is best in predicting dye removal efficiency with R2 = 0.97 and RMSE = 3.59. The developed model can be used as a useful tool to optimize treatment processes using the promising adsorbent, to eliminate basic dyes from aqueous solutions. Adsorption followed a pseudo-second order kinetics and was best described by the Freundlich isotherm. Encapsulating the kaolin powder in sodium alginate resulted in removal efficiency of 99.56% and a maximum adsorption capacity of 188.7 mg.g−1, a more than fourfold increase over kaolin alone.

In this study, the chemical modification of chitosan using itaconic acid as a natural-based unsaturated dicarboxylic acid was investigated. In an aqueous environment, the amine group of chitosan reacts with itaconic acid to produce a chitosan derivative with pyrrolidone-4-carboxylic acid group. On the basis of the elemental analysis, 15% of the amine groups of chitosan reacted, thus creating modified chitosan with amine and carboxylic acid functionalities. Due to the presence of amine and carboxylic acid groups, the surface charge properties of the chitosan were notably altered after itaconic acid modification. In an aqueous solution, the modified chitosan exhibited zwitterionic properties, being cationic at low pH and turning anionic when the pH was increased over 6.5, whereas the original chitosan remained cationic until pH 9. Furthermore, it was demostrated that the modified chitosan was suitable for the preparation of a self-standing film with similarly high transparency but notably higher mechanical strength and oxygen barrier properties compared to a film made from the original chitosan. In addition, the thermal stability of the modified chitosan film was higher than that of the original chitosan film, and the modified chitosan exhibited flame-retardant properties.

A novel method based on the use of reactive eutectic media for the extraction of cellulose nanocrystals and their functionalization with positively charged functional groups in a one-step procedure is presented. With its ability to form strong hydrogen bonds, the eutectic medium serves as a cellulose-solubilizing agent, while the presence of a Leuckart reagent provides the reactivity toward the reductive amination of carbonyl groups in the cellulose chains. In the proposed method, amorphous cellulose domains are partially dissolved by undergoing aminolysis, resulting in the formation of water-dispersible nanocellulose products with high crystallinity.

The strength of the acid sites in isostructural hierarchical porous zeolites increases in the order BSiO < GaSiO < AlSiO, and the concentration in the structural types increases in the order MTW < BEA < MOR. Zeolite materials with BEA and MOR topology, which consist of nanocrystals with ultrathin-layer morphology, are characterized by a marked decrease of the adsorption potential compared with isostructural materials with nanorods or nanosphere morphology due to a 1.5-fold decrease in the isosteric heats of adsorption of triethylamine.

BaCe 0.7 Y 0.2 In 0.1 O 3–δ (BCYI) compositions were prepared by a modified Pechini method, following this the ceramic samples were consolidated using conventional sintering (CS) and spark plasma sintering (SPS) at 1250–1500 °C for 3–10 min. The structural and microstructural characteristics of the samples were determined using XRD, SEM and TEM. The total, bulk and grain boundary ionic conductivities were evaluated using the AC impedance method in dry air, wet air and dry Ar. It was shown that application of SPS in case of nanocrystalline BCYI allows to reduce the sintering time, and in case of microcrystalline BCYI application of SPS after CS allows to improve hardness and total conductivity through reduction of grain boundary resistance.

Potentiometric titration was used to characterize the acid-base properties of micro-mesoporous zeolite-like materials obtained via dual template synthesis using sol-precursors of Beta zeolite and micellar templates. The obtained results were compared with other methods of acidity determination (ammonia TPD, pyridine ad(de)sorption). The acid sites with the strength comparable to Beta zeolite (lg K values 4.3–4.7) were found in low-crystalline and X-ray amorphous micro-mesoporous materials. The strongest acid sites were observed in conventional Beta zeolite and a low-crystalline (degree of crystallinity ca. 0.1) micro-mesoporous material prepared on its basis (lg K 4.3) in concentration of 450 and 100 μmol/g, respectively. A change from acidic to alkaline reaction media in the second stage of micro-mesoporous materials preparation led to an increase of the acid sites concentration from 190 to 600 μmol/g concomitant with formation of a high fraction of comparatively strong acid sites (lg K 4.7, 200 μmol/g). A high content of acid sites in low-crystalline and X-ray amorphous samples was assigned to acidity of zeolite precursors rather than zeolite crystals.

Samples of porous silicon carbide were obtained using sucrose or carbon and aerosil or silica mesoporous molecular sieves (SBA-3, SBA-15, KIT-6 and MCF). Fibers content in silicon carbide samples is higher when the mesopore surface area of carbon materials derived from carbon-silica composites is lower. Based on the found correlation between the morphology and porosity of SiC and mesopore surface area of the carbon component in the composites, a templating action of carbon in carbothermal reduction was suggested.

Titanium-manganese mixed oxides TiO2/MnOx (TMO) were prepared by chemical precipitation of manganese hydroxide on pure nanocrystalline rutile TiO2 particles with subsequent thermal treatment at different temperatures. The morphology, structural and optical properties of TMO samples were investigated using standard XRD, SEM, EDS, XRF, TGA, FT-Raman and UV–vis absorption spectroscopic techniques. The photoluminescence (PL) in TMO was excited by the UV laser pulses (337.1 nm). All measurements were carried out at room temperature. Examination of PL spectra revealed that they are strongly dependent on the phase composition and Mn concentration in TMO compounds. The quenching of the PL is connected with the oxygen vacancies in the TMO structure, in particular, the intensity lowering for the near band edge emission at 3.06 eV (405 nm) and the free exciton emission at 2.92 eV (424 nm) is interpreted by the non-radiative Auger recombination. The relative increase and decrease in the ratio of PL intensities for UV and visible bands with increasing Mn content (from 9 to 16 at%) is explained by the concentration effects.

Partly zeolitized micro-mesoporous aluminosilicates SBA-15/ZSM-5 were synthesized by conversion of dry gel of template-containing SBA-15 in the presence of tetrapropylammonium hydroxide. They have a hexagonally ordered mesostructure and developed surface and mesoporosity for which the concentration and strength of the Bronsted and Lewis acid sites are higher than in AlSi-SBA-15. The formation of Bronsted acid sites of moderate strength in the samples with a low degree of zeolitization is due to the presence of ZSM-5 precursors as well as crystallites in the obtained aluminosilicates.

Heat treatment of carbon–silica composites derived from micro-mesoporous zeolite-like materials yields the β-modification of silicon carbide with adsorption characteristics much superior to those of analogs obtained using large-porous silica exotemplates (meso-cellular foams). The presence of a large volume of relatively homogeneous mesopores, which permits us to achieve a close-to-stoichiometric C/SiO2 ratio, accounts for the formation of silica carbide with well-developed porosity.

Samples of crystal modifications of porous silicon carbide were obtained by carbothermal method using carbon precursors (sucrose, carbon) and aerosil or mesoporous silicas molecular sieves SBA-3, SBA-15, KIT-6, and MCF as silicon sources. Porous β-SiC samples obtained from carbon–silica composites are characterized by high structural and sorption characteristics (S BET up to 410 m2/g, V pore up to 1.0 cm3/g). High hydrogen adsorption capacity of silicon carbide samples based on KIT-6 (up to 1.24 wt% at 77 K and 1 atm.), considering low adsorption energy ( $$ \left| {\Delta \mu_{0} } \right|_{{{\text{H}}_{2} }} $$ ) up to 2.3 kJ/mol for SiC vs. ca. 5.0 kJ/mol for carbon), was determined. The highest ever reported value among the existing porous materials was observed for specific adsorption of H2 by SiC (specific adsorption on the pore surface, ρ up to 15 μmol/m2) corresponding to almost complete filling of the surface with hydrogen in the examined conditions (77 K, 1 atm.).

The possibility of obtaining foam-like copper (I) oxide and the process of carbon dioxide photocatalytic reduction under its participation were studied. It was shown that this material had a high photocatalytic activity in gas phase CO2 reduction with water vapor to acetaldehyde (up to 8.2 μmole·gcat−1·h−1) and methane (up to 19.2 μmole·gcat−1·h−1). A similar effect can be explained both by the formation of nanocrystalline Cu2O and the spatial organization of such components into the foam-like three-dimensional (3D) material. Based on the distribution of the final products conclusions about the possible mechanism of CO2 conversion during a transition from an irradiation with the full spectrum of a lamp to UV and visible light were made.

In this paper, we propose a new approach for valorization of monosaccharides derived from biomass into value added chemicals in a green and economically efficient manner by forming eutectic medium exclusively between reactants. Eutectic mixtures are emerging as an advantageous alternative to ionic liquids and have already found broad applications in biomass treatment; however they are preferably used only as low vapor pressure solvents. Increasing interest in eutectic solvents originates from their flexibility to adjust their properties to different biorefinery needs by simple variation of the compositions of eutectic mixtures. In this work, we made a first attempt to use a low molecular weight component, ammonium formate, to significantly change the physical properties of the eutectic mixtures and simultaneously increase their chemical reactivity. Using this approach, we valorised simple monosaccharides by turning them into fructopyrazines with high yields in their eutectic mixtures with ammonium formate. The research revealed a high sensitivity of the product yields to the temperature of the reaction and composition of the eutectic medium, as well as an important role of formate anions in product stabilization.

Boron-doped carbon nanostructures were obtained via template and bulk synthesis from sucrose in the presence of boric acid. Synthesized B-containing mesoporous materials are characterized by high spatial ordering, developed surface (up to 870 m2/g), and porosity (up to 1.2 cm3/g). The obtained B-doped microporous materials exhibit high interfacial capacitance (up to 0.36 F/m2), which is higher than the available literature data and enables the use of synthesized samples as materials of supercapacitors. The capacity of electric double layer up to 300 F/g using sulfuric acid as the electrolyte was accumulated on microporous B-doped carbons.

S-doped porous carbon nitride was obtained by a simple method using melamine and sulfuric acid. The synthesized material exhibits high BET specific surface area (75 m2/g) compared to non-doped C3N4 (25 m2/g). According to X-ray photoelectron spectroscopy sulfur atoms substitute nitrogen forming C−S bonds in the structure of carbon nitride. Incorporation of sulfur into C3N4 results in a significant increase of the light absorbance intensity especially in the UV region compared to undoped sample. Synthesized S-doped carbon nitride was found to be p-type semiconductor with high catalytic activity towards photoreduction of carbon dioxide with water vapour. Doping C3N4 with sulfur increases the catalytic activity in this reaction almost tenfold.

The samples of nonstoichiometric carbon nitride characterized by spatial ordering, large pore volume (up to 0.8 cm3/g) and specific surface area (up to 585 m2/g) were obtained via matrix carbonization of ethylenediamine in the presence of carbon tetrachloride in mesoporous molecular sieves KIT-6 and MCF as exotemplates. In contrast to nitrogen-containing carbons (obtained by modification of carbon samples with nitrogen in the result of compatible thermal treatment of the initial porous carbon with melamine) nonstoichiometric carbon nitride contains much more nitrogen (up to 13.7 wt.% (C/N = 6), compared with preceding 0.6 wt.%) and increased the quantity of basic nitrogen-containing groups (in particular, amino groups)—up to 0.68 mmol/g (vs. 0.46 mmol/g). The increase of adsorption capacity towards hydrogen and carbon dioxide: adsorption potential, differential heat of CO2 adsorption, specific adsorption on the pore surface—from 5.4 to 7.3 μmol H2/m2 and from 2.2 to 5.4 μmol CO2/m2 for carbon and synthesized samples of nonstoichiometric carbon nitride, respectively, due to the incorporation of nitrogen atoms into the carbon framework was noticed.

Porous carbon nitrides of different morphology were obtained via bulk and hard template (SBA-15 and MCF) pyrolysis of melamine. Matrix method allowed obtaining ordered porous C 3 N 4 with higher bandgap (2.87 eV) in the contrary to the bulk sample (2.45 eV). Obtained carbon nitrides were found to be p-type semiconductors with catalytic activity towards photoreduction of carbon dioxide with water vapour. Carbon nitride obtained in MCF has the higher bandgap, developed surface, sponge-like morphology, spatially ordering and it's characterized by the highest photocatalytic activity.

In this work, we prepared CdTe quantum dots, and series of Cd1-xMnxTe-alloyed quantum dots with narrow size distribution by an ion-exchange reaction in water solution. We found that the photoluminescence peaks are shifted to higher energies with the increasing Mn2+ content. So far, this is the first report of blue-emitting CdTe-based quantum dots. By means of cyclic voltammetry, we detected features of electrochemical activity of manganese energy levels formed inside the Cd1-xMnxTe-alloyed quantum dot band gap. This allowed us to estimate their energy position. We also demonstrate paramagnetic behavior for Cd1-xMnxTe-alloyed quantum dots which confirmed the successful ion-exchange reaction. Electronic supplementary material The online version of this article (10.1186/s11671-018-2529-y) contains supplementary material, which is available to authorized users.

Silicon carbide in the $$ \beta $$ modification with a developed surface and a large pore size was obtained by carbothermal reduction using mesoporous siliceous molecular sieves (SBA-15, KIT-6, MCF, SBA-3). The formation of silicon carbide with high porosity parameters is favored by the use of the KIT-6 mesoporous molecular sieve (MMS) with a three-dimensional structure and a mutually intersecting system of mesopores as matrix, by the close to the stoichiometric C/SiO2 ratio, and also by the higher level of filling with carbon in the pores of the siliceous MMS.

Solid-liquid phase transitions in Cd0.95-xMnxZn0.05Te alloys with x = 0.20 and 0.30 were investigated by differential thermal analysis (DTA). The heating/cooling rates were 5 and 10 K/min with a melt dwell time of 10, 30 and 60 minutes. Cd0.95-xMnxZn0.05Te (x=0.20, 0.30) single-crystal ingots were grown by the vertical Bridgman method guided by the DTA results. Te inclusions (1-20 micron diameter), typical of melt-grown CdTe and Cd(Zn)Te crystals, were observed in the ingots by infrared transmission microscopy. The measured X-ray diffraction patterns showed that all compositions are found to be in a single phase. Using current-voltage (I-V) measurements, the resistivity of the samples from each ingot was estimated to be about 105 Ohm·cm. The optical transmission analysis demonstrated that the band-gap of the investigated ingots increased from 1.77 to 1.88 eV with an increase of the MnTe content from 20 to 30 mol. %.

Carbon–silica composites were obtained by uniformly coating the entire pore surface of SBA-15 and KIT-6 with a thin carbon layer using a 2,3-dihydroxynaphthalene as a carbon source. Due to formation of uniform carbon coating obtained composites possesses electrical conductivity despite the insulative nature of the silicas and thus exhibit ohmic curves. The specific capacitance per surface area of carbon–silica composites is higher than those of conventional activated carbons due to carbon–silica composites exhibited capacitance from electric double-layer and a time-consuming process between carbon surface and H2SO4 electrolyte similar to pseudocapacitance. This allows considering such composites as electrode materials with uniform pores. The Hydrogen initial potential for adsorption |Δµ 0| and density of pore surface filling with hydrogen for the composite with higher carbon content (24.7 µg/m2) is more than 5 times higher than for the initial silica (4.6 µg/m2) and approximately 2 times higher than for the composite with lower carbon content (10.4 µg/m2). |Δµ 0| for the obtained porous carbons is higher (5.2 kJ/mol) than for the initial matrices (2.8 kJ/mol) and carbon–silica composites (3.7–5.1 kJ/mol).

Meso- and microporous nitrogen-containing carbons, characterized by homogeneous meso- (V = 1.00 cm3/g, D = 3.5 nm) and microporous (V up to 0.26 cm3/g, D ≈ 0.5 nm) structure, and the presence of basic groups (up to 1.7 mmol/g) were obtained by matrix and bulk carbonization of sucrose in the presence of melamine or urea. It is shown that obtained N-containing microporous carbons possess good interfacial capacitance (0.21 F/m2) and they are characterized with stability during repeated charge–discharge cycles. Synthesized N-containing nanoporous carbons show higher adsorption of carbon dioxide (up to 6.3 mmol/g at −20 °C) than the samples without nitrogen (up to 3.9 mmol/g at −20 °C).

Microporous, mesoporous, and new hybrid materials were studied in verbenol oxide isomerization for the synthesis of biologically active substance with anti- Parkinson activity. H-Si-MCM-41, H-Al- MCM-41, H- Al- MCM-48, H-Beta-25, and H-Beta-300 were compared with hybrid materials. The latter with a zeolite-like micromesoporous structure were characterized and evaluated for their catalytic activity for the first time. The approach of dual templating for synthesis of new materials was applied in this work to combine properties of Beta-zeolites and mesoporous cellular foams (MCF). The selectivity to the target product was the highest over microporous mild acidic H-Beta- 300 and hybrid ZF-100, with also mild acidity and even absence of strong acid sites. Selectivity at 97 and 99% of conversion was 61 and 59% for H-Beta-300 and hybrid ZF-100, respectively.