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This paper considers possible uses of fruit-based waste for the production of valuable chemicals and biofuel precursors through recycling by thermochemical conversion. Slow pyrolysis of goji berry mesocarp as sugar-riched feedstock was investigated using simultaneous thermal analysis measurements in non-isothermal conditions. This work announced that pyrolysis of goji berry mesocarp represents a promising route to obtaining an important key platform chemical - 5- hydroxymethylfurfural (5-HMF). To establish the process mechanism, two kinetic approaches were used for kinetic parameters determination: first, Friedman’s and Vyazovkin’s model-free (inverse) methods supported by numerical optimization of the process, and second, the modelbased (direct) method. Model-free results showed a complex evolution of activation energy with conversion, indicating a multi-step mechanism. It was found that autocatalytic dehydration of fructose (in the presence of Lewis acids) is responsible for the production of 5-HMF at a low heating rate (5.0 K/min) with a maximum 5-HMF theoretical yield of 63.20 %. Higher heating rates (10.0 K/min and 15.0 K/min) trigger the fructose autogenesis behavior which opens the transferability channel to glucose (substrate) engagement for 5-HMF theoretical high yield production. It was revealed that differences between kinetic parameters are a consequence of the change in the mechanism of glycosidic bond cleavage. The validity of the proposed reaction mechanism scheme and accuracy of kinetic parameters was confirmed by modulated dynamic predictions.

This paper considers possible uses of fruit-based waste for the production of valuable chemicals and biofuel precursors through recycling by thermochemical conversion. Slow pyrolysis of goji berry mesocarp as sugar-riched feedstock was investigated using simultaneous thermal analysis measurements in non-isothermal conditions. This work announced that pyrolysis of goji berry mesocarp represents a promising route to obtaining an important key platform chemical - 5-hydroxymethylfurfural (5-HMF). To establish the process mechanism, two kinetic approaches were used for kinetic parameters determination: first, Friedman’s and Vyazovkin’s model-free (inverse) methods supported by numerical optimization of the process, and second, the model-based (direct) method. Model-free results showed a complex evolution of activation energy with conversion, indicating a multi-step mechanism. It was found that autocatalytic dehydration of fructose (in the presence of Lewis acids) is responsible for the production of 5-HMF at a low heating rate (5.0 K/min) with a maximum 5-HMF theoretical yield of 63.20 %. Higher heating rates (10.0 K/min and 15.0 K/min) trigger the fructose autogenesis behavior which opens the transferability channel to glucose (substrate) engagement for 5-HMF theoretical high yield production. It was revealed that differences between kinetic parameters are a consequence of the change in the mechanism of glycosidic bond cleavage. The validity of the proposed reaction mechanism scheme and accuracy of kinetic parameters was confirmed by modulated dynamic predictions.

Polymers and polymer composites have wide application in every industrial field, and are a subject of continuous research from different scientific aspects [1,2]. However, most commercial polymers are oil refinery based products. Recently, due to a growing concern for oil depletion, researchers have been focused on modification of polymers, as well as reinforcements [3,4]. Epoxy resin is the most commonly used adhesive that can be improved with fiber or particle reinforcements, or by using chemical modifiers. Modifying agents from renewable resources show potential in replacing oil-based compounds, because of their abundance, low price and heterogeneous structure that offers number of reactive groups [5]. In our research, honey was used as a bio-based modifier for diglycidyl ether of bisphenolA (DGEBA) based epoxy resin, with the aim of investigating structural changes. MALDI-TOF mass spectrometry [6] was used as a powerful technique that is able to reveal presence of functional groups and modified epoxy resin structure. In this manner, successful chemical modification of epoxy resin was confirmed, which further opened the path for the investigation of honey potential as epoxy modifying agent.

In order to clarify relationship between apricot kernel shell biomass slow pyrolysis mechanism and its main constituents (viz. hemicelluloses, cellulose and lignin), the reactivity effects of main constituents on pyrolysis characteristics were determined by the non-isothermal simultaneous thermal analysis. It was found that four-step (parallel) reaction model is suitable for studying the slow pyrolysis process, within the semi-global model which excludes the strong interaction between biomass constituents (pseudo-components). The application of the proposed model was allowed by the results obtained from KAS iterative isoconversional (model-free) approach. The valorization of the model was confirmed by the process optimization. The complex (cumulative) apricot kernel shell pyrolysis rate curves at different heating rates are successfully resolved into the individual decomposition rate curves (arising from thermal conversion of hemicelluloses, cellulose, and primary/secondary lignin fragments) by four-parameter Fraser–Suzuki function. Besides hemicelluloses and cellulose pyrolyses, the proposed model distinguishes primary and secondary lignin reactions, which enhance the gaseous products releasing (primarily CO and CO2 gases) and charification of the solid residue (increased the bio-char yield). © 2020, Akadémiai Kiadó, Budapest, Hungary.

Thermo-analytical characterization of selected biomasses (agricultural waste and wood biomass feedstock) through the pyrolysis process was performed under dynamic conditions. Slow pyrolysis (carbonization) regime (with a heating rate below 50 °C min−1) was selected because it favours the residual solid (bio-carbon/bio-char) in the higher yields (change in the surface area of bio-char with pyrolysis conditions was dependent on the type of biomass feedstock). Comparison of results and discussions related to obtained percentage pyro char yields from thermo-chemical conversion of biomass feedstocks were generated from simultaneous thermal analysis (STA) (TGA-DTG-DTA apparatus). The analysis of gaseous products of pyrolysis was carried out using mass spectrometry (MS) technique. Releasing of the light gaseous compounds (mainly CO, CO2, CH4, and H2 non-condensable gases) was monitored simultaneously with TGA measurements. Discussion related to this issue was performed from the aspect of the syngas production, as well as the versatility of selected biomasses in the gasification process where the various gasifying agent may be in use. © Springer Nature Switzerland AG 2020.

This paper investigates the ability of waste apricot (Prunus armeniaca) kernel shells (AKS) bio-char prepared by single-step carbonization process at 850 °C (residence time of 1 h) for possible removal of toxic elements and organic micro-pollutants. The experiment that was performed as well as parameters used proved to be optimal for bio-char production as adsorbing medium, where last issue is validated by multiform material characterization techniques. It has been shown that the produced bio-char possess highly-porous morphology features, with large specific surface area (328.570 m2 g−1). The obtained product was characterized by various pore sizes (including super-micropores and mesopores with maximum pore size of 2.24 nm) structures. Preliminary results are indicated that obtained bio-char can shows increased affinity to possible adsorption of the small organic molecule contaminants upgraded by its physico-chemical properties. Cost estimation of AKS bio-char production substantiated its cost effectiveness and its good physical and chemical properties for future design in batch adsorption and regeneration tests. It was established that AKS produced bio-char was 2.5 times cheaper than the commercially available activated carbon. Bio-char exhibits promising removal performances for potential adsorption of heavy metal and organic micro-pollutants from wastewaters systems, as indicated by material textures and spectroscopy measurements. © 2019 Elsevier Ltd

Pyrolysis of lignocellulosic biomass is a promising process capable of producing renewable fuels and chemicals that are currently derived from non-renewable sources. However, industrial pyrolysis processes to make these products from biomass are not yet economically viable and require significant optimization before they can contribute to existing oil-based transportation and chemical systems. One means of optimization uses kinetic and transport models for predicting the products of biomass pyrolysis, which serve as the basis for designing pyrolysis reactors capable of producing the highest value products. In this work, two computational approaches applied in modeling the complex pyrolysis process of biomass were presented. First approach encompasses iterative isoconversional method established in generic codes in MATLAB program. Second approach represents the use of Fraser-Suzuki fitting function for resolving the rate curves that arise from complex process of lignocellulosic materials. In the latter case, every identified reaction step was considered through mechanistic description, which involves selection the appropriate kinetic model function. Comparison of the results as well as discrepancies between them has been discussed. As an example, the slow pyrolysis of apricot (Prunus armeniaca) kernel shells was taken into the consideration, where devolatilization process is monitored using the simultaneous thermal analysis (STA).

Polychlorinated biphenyls (PCBs) are the most highly toxic species of POPs. More than 200 PCB congeners exist in nature. [1] PCBs are highly toxic for humans. They enter the human body via inhalation, ingestion or sorption through the skin and the bloodstream transports them to the organs, muscles and adipose tissues, where they are accumulated. This study presents the validation of analytical method for determination of 7 PCBs congeners in soil: PCB 28, PCB 52, PCB 101, PCB 118, PCB 153, and PCB 180. The method is based on solid- liquid extraction with cyclohexane and the analysis by gas chromatography with mass spectrometric detection (GC-MS). [2] Samples were analyzed in SIM mode, and the analytes qualitative confirmation was performed comparing the mass spectra of analytical standards of PCB congeners with the NIST data base. The method developed can be applied in range from 0,005 to 10 mg/kg with the appropriate parameters of precision, accuracy, repeatability and linearity and can be used for simultaneous determination of low PCBs concentrations in different types of soil (agricultural, contaminated soil, etc.).

The estimation of uncertainty measurement using different approaches is increasingly applied to assess the reliability of results generated by applied analytical methods. This paper presents the Monte Carlo simulation model (MCS) for calculating the uncertainty of the measurement associated with the result of the analysis. The results of MCS were compared with the commonly used a standard method (GUM). The calculations of the measurement uncertainty were demonstrated in the case of the determination of 2,4-dimethylphenol by gas chromatography in concrete samples.