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In this study, bionanocomposite films based on poly(lactide) (PLA) plasticised with poly(ethylene glycol) (PEG) (7.5 wt%) and reinforced with various contents of nanofibrillated cellulose (NFC) (1, 3, 5 wt%) were prepared. The hydrothermal degradation was investigated through immersion in several aqueous environments at temperatures of 8, 23, 58, and 70 °C as a function of time (7, 15, 30, 60, 90 days). The effect of water immersion on the physicochemical properties of the materials was assessed by monitoring the changes in the morphology, thermo-oxidative stability, thermal properties, and molar mass through field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The hydrothermal degradation behaviour was not critically affected regardless of the nanofibrillated cellulose content. All the materials revealed certain integrity towards water immersion and hydrolysis effects at low temperatures (8 and 23 °C). The low hydrothermal degradation may be an advantage for using these PLA biocomposites in contact with water at ambient temperatures and limited exposure times. On the other hand, immersion in water at higher temperatures above the glass transition (58 and 70 °C), leads to a drastic deterioration of the properties of these PLA-based materials, in particular to the reduction of the molar mass and the disintegration into small pieces. This hydrothermal degradation behaviour can be considered a feasible option for the waste management of PLA/PEG/NFC bionanocomposites by deposition in hot aqueous environments. [ABSTRACT FROM AUTHOR]

This paper presented a novel process for production of furfural by hydrothermal degradation of corncob over biochar catalyst, in which it was prepared with the recycling degradation solution and lignocellulosic solid residues. The biochar catalyst was papered by lignocellulose residues and concentrated saccharide solution, and then impregnated in 0.5 mol/L sulphuric acid at room temperature for 24 h assisted by the ultrasonic vibration. In the system of recycling, 8.8 % lignocellulose residues and 100 % concentrated saccharide solution from corncob hydrolysis have been recycled. Hydrolysis of corncob was carried out at 180 °C for duration of 170 min over the biochar catalyst. The experimental results have shown that the furfural yield of up to 37.75 % and overall corncob conversion rate of 62.00 % could be achieved under optimum operating conditions for the catalysts preparation and the corncob hydrolysis. It is believed that the acid density of 4.27 mmol/g of biochar catalyst makes the SOH groups cleave β-1,4 glycosidic linkages effectively and hydrolyze the cellulose and hemicellulose to water-soluble sugars, as well as to facilitate dehydration of xylose to give the product of furfural. [ABSTRACT FROM AUTHOR]

Recycled natural materials such as silk fabric have attracted more and more public attention over the past few years. In this research, unsaturated polyester resin was used as matrix, glass mat and silk fabric were employed as reinforcement to fabricate the laminated hybrid composites by hand lay-up method. Three-point flexural quasi-static and load-controlled low cycle bending fatigue (LCBF) tests at 55 %, 70 % and 85 % pre-set load levels were performed. The composite specimens were also subjected to hot water immersion treatment at 80 oC for different durations. The effects of the immersion treatment on the bending and impact fracture characteristics were investigated. The results showed that higher flexural modulus and strength were obtained when silk fabric layer was stacked at the middle layer. It seems that the antifatigue property was improved by the inclusion of silk fabric reinforced in glass mat hybrid composites. In the water immersion experiments, both the flexural properties and impact properties were improved initially until reaching the maximum and then decreased continuously with further increase in exposure time. These seemingly contradictory behaviors are due to relaxation of the internal stress, swelling of the silk fibers and the weakening of fiber/matrix interface. [ABSTRACT FROM AUTHOR]

The main aim of this study was to evaluate pressurized hot water as a green and environmentally friendly extraction medium for the isolation of phenolic compounds from larch waste wood. Such isolates could find applications in the food, feed, pharmaceutical and cosmetics industries or as natural ingredients for adhesives or biocidal coatings in the wood industry. In the first step different larch wood fractions were extracted using batch system aiming to determine the most suitable fraction for isolation. The content of extractives, total phenolic and tannin content of obtained extracts and their antioxidant activity were evaluated. Secondly, semi-continuous operation was applied, where effects of temperature, addition of ethanol and flow rate were studied. Extraction yield was monitored and extracts were again analyzed for their total phenolic content and antioxidant activity. HPLC analysis was performed, in order to study the effect of temperature and addition of ethanol on the hydrothermal degradation of phenolics during semi-continuous operation. Finally, the economics of pilot-scale and industrial-scale processes with different extractor capacities, ranging from approximately 12 to 1200 kg of woody material per day and operating at optimal conditions for isolation of larch wood extractives was evaluated, in order to determine the cost of manufacturing of such a product. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Electrolysis in subcritical water can convert biomass-derived saccharides into value-added chemicals and fuels without any additives. In this work, we aim to understand reaction behaviours of glucose under subcritical water degradation or electrochemical conditions for the purpose of developing a new method for producing useful carboxylic acids. Degradation of glucose was carried out using a continuous flow-type reactor in subcritical water at various operating conditions, and electrochemical reactions of their product solutions were conducted at identical conditions with a 500-mL batch autoclave. Gaseous products obtained were analyzed by gas chromatography-thermal conductivity detection (GC-TCD), and liquid products were analyzed by high-performance liquid chromatography (HPLC) and gas chromatography-flame ionization detection (GC-FID). The total organic carbon (TOC) in the aqueous product solution was determined by using a TOC analyzer. Based on the experimental results, a reaction pathway for glucose is proposed for subcritical water degradation and electrolysis. [ABSTRACT FROM AUTHOR]

In the present work, polylactic acid, PLA, samples were degraded by hydrothermal treatment, and then their molecular weights, crystallinity, surface charges and compositions, were determined, respectively, by using viscometry, H NMR, Differential Scanning Calorimetry (DSC), microelectrophoresis and Infra Red spectroscopy methods. The viscometry and H NMR data indicate that the molecular weight, of the polymer, decreases after the hydrothermal treatment. However, the crystalline fractions of the PLA samples, as obtained from the DSC and X-ray data, were not altered after the hydrothermal treatment. Furthermore, the zeta potential data, as determined by microelectrophoresis, show for both non-degraded and degraded PLA, an increase of the polymer surface charge density with the pH of the aqueous phase. However, at acidic pH values, the surface charge density for the degraded PLA was higher as compared to the non degraded one. These differences in surface charge densities of the PLA samples were confirmed by Infrared study, according to which the spectra of degraded polymer show the appearance of carboxyl groups occurring at 1,600 cm at the polymer surface. [ABSTRACT FROM AUTHOR]

This paper considers the combination of hydrothermal degradation (HTD) and superheated steam (SHS) drying in disposal and processing of degradable organic wastes in municipal solid wastes (MSW). In SHS drying, a fraction of dryer thermal energy input can be recovered and used to satisfy the heat requirement in maintaining the HTD operating temperature. Both energy and exergy analysis are applied to the combined process. The analysis covers ranges of dryer inlet temperatures of 202.38–234.19°C and feed water content of 32.5–65%. Thermal energy analysis shows that the combination of HTD and SHS drying can achieve thermal energy self-sufficiency (TES) by manipulating process variables. The exergy analysis indicates the location, type, and magnitude of the exergy losses during the whole process by applying the second law of thermodynamics. [ABSTRACT FROM AUTHOR]