Analytical Pyrolysis of Soluble Bio-Tar from Steam Pretreatment of Bamboo by Using TG-FTIR and Py-GC/MS.

Steam pretreatment at high temperatures enables fresh bamboo to possess antifungal and antiseptic properties. The process produces a large amount of wastewater that urgently needs to be recycled. Soluble bio-tars derived from wastewater under low-temperature (LTS-tar) and high-temperature (HTS-tar) steam pretreatments of moso bamboo were studied with a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis-gas-chromatography/mass spectrometry (Py-GC/MS). Thermogravimetric analysis showed that in the three stages of the thermal decomposition process, the final residue of the bamboo and HTS-tar had two main peaks of 0.88 wt% and 6.85 wt%. The LTS-tar had much more complicated thermal decomposition behavior, with six steps and a high residue yield of 23.86 wt%. A large quantity of CH4 was observed at the maximum mass loss rates of the bamboo and bio-tars. Acids, aldehydes, ketones, esters, and phenolic compounds were found in the pyrolysis products of the bamboo and soluble bio-tars. Both bio-tars contained carbohydrates and lignin fragments, but the LTS-tar under mild steam conditions had more saccharides and was much more sensitive to temperature. The lignin in the bamboo degraded under harsh steam conditions, resulting in high aromatic and polymeric features for the HTS-tar. The significant differences between LTS-tar and HTS-tar require different techniques to achieve the resource utilization of wastewater in the bamboo industry.

Suspected sources of microplastics and nanoplastics: Contamination from experimental reagents and solvents.

There is an increasing concern about the potential effects of microplastics (MPs) and nanoplastics on human health and other organisms. For the separation and detection of MPs, there are various approaches, and the distinct procedures led to different results. However, the presence of MPs in the reagents was not addressed, which could cause false and/or inaccurate results during MPs detection. In this study, the chemical reagents commonly used for the separation and detection of MPs were selected to ascertain whether these reagents introduce MPs. It was shown that a large number of MPs were detected in the reagent and solvent samples. The largest number of MPs (>1 µm) was detected in the KOH reagent, with the abundance of 3070 items/g. The order of MPs abundance in the selected reagents was: KOH > NaCl > CaCl2 > SDS > NaI > H2O2. The types of MPs were the same as the body and stopper of the reagent packaging bottles. MPs size detected in reagent bottles was primarily smaller than 10 µm. The abundance of MPs in the reagents were independent of their purity, however, there was a certain difference in MPs abundance in reagents from different manufacturers. Furthermore, the presence of nanoplastics (< 1 µm) was verified in the reagents through Py-GCMS, with the abundance (39.47-43.01 mg/kg) higher than that of MPs. The obtained results in this study raised specific requirements and cautions for MPs and nanoplastics related research in terms of quality control. Also, this work can facilitate a more accurate assessment of MPs concentrations in the environment.

Extraction and Characterization of Acidolysis Lignin from Turkey Oak (Quercus cerris L.) and Eucalypt (Eucalyptus camaldulensis Dehnh.) Wood from Population Stands in Italy.

Acidolysis lignins from the species Quercus cerris L. and Eucalyptus camaldulensis Dehnh. were isolated and characterized using high pressure size exclusion chromatography (HP-SEC), Fourier-transform (FTIR) infrared spectroscopy, analytical pyrolysis-gas chromatography-mass spectrometry (Py-GCMS), and two-dimensional heteronuclear single quantum coherence (2D HSQC) NMR spectroscopy. The acidolysis lignins from the two different species varied in chemical composition and structural characteristics, with Q. cerris L. lignin having a higher S/G ratio and higher molar mass averages with a bimodal molar mass distribution. The different analytical techniques FTIR spectroscopy, Py-GCMS, and 2D NMR spectroscopy provided consistent results regarding the S/G ratio of the lignins from the two wood species. Based on the determined high S/G ratio of both oak and eucalypt lignin, the two wood sources could be promoted as substrates for efficient lignin isolation in modern forest biorefineries in order to develop innovative lignin-based value-added biorefinery products.

Thermal degradation of cyanidin-3-O-glucoside: Mechanism and toxicity of products.

The thermal degradation behavior of cyanidin-3-O-gluoside (Cy3G) in nitrogen and air was studied using thermogravimetric analysis (TGA), thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GCMS). The results show that the thermal degradation of Cy3G in nitrogen and in air can be divided into three steps. The total degradation rate was 63.09% in nitrogen and 99.42% in air, and the total activation energy (Ea) was 65.85 and 80.98 kJ·mol-1, respectively. The TG-FTIR analysis showed that Cy3G is significantly decomposed at 200-300 °C. The Py-GCMS analysis shows that the first step in the thermal degradation of Cy3G in nitrogen is the cleavage of glycosidic bonds to give cyanidin and glucoside. The glucoside and cyanidin then degrade further to give mainly low molecular weight compounds, together with furan derivatives, pyran derivatives and aromatic compounds. The phenols and furans found in the pyrolysis products are known to have a degree of toxicity.

Ex-situ catalytic pyrolysis of chicken litter for bio-oil production: Experiment and characterization.

The depletion of fossil fuels has been a greater concern to the world due to the demand for energy that tremendously increasing with urbanization and population growth. For sustainable development, power industries are trying to find suitable substitute of petroleum fuel which is environment friendly and economically feasible. The biomass such as the production of bio-oil from chicken litter could be a possible alternative source of energy. The conversion of the feedstock was conducted through a catalytic pyrolysis process in an ex-situ fixed bed reactor heated at 500 °C with a heating rate of 50 °C/min. Proximate, ultimate, and calorific analysis of the feedstock was studied using TGA/DTG analysis, CHNS, and bomb calorimeter, respectively. GCMS and py-GCMS experiments on the bio-oil showed that the HHV of the feedstock was 16.01 MJ/kg. The addition of catalyst improved the quality of the bio-oil yield. The presence of dolomite and ZMS-5 catalyst enhances the phenols and aromatic content, respectively. Biomass to catalyst (B/C) ratio increased the oil production from 43.6g to 51.9g for dolomite and 43.6g-47.1g for ZMS-5 with the B/C ration of 20g:3g. Elevating the B/C ratio increases the pyrolytic liquid yield with greater influence on the furanic compound.

Nanoplastics Identification in Complex Environmental Matrices: Strategies for Polystyrene and Polypropylene.

Identification of nanoplastics in complex environmental matrices remains a challenge. Despite the increase in nanoplastics studies, there is a lack of studies dedicated to nanoplastics detection, partially explained by their carbon-based structure, their wide variety of composition, and their low environmental concentrations compared to the natural organic matter. Here, pyrolysis coupled to a GCMS instrumental setup provided a relevant analytical response for polypropylene and polystyrene nanoplastic suspensions. Specific pyrolysis markers and their indicative fragment ions were selected and validated. Possible interferences with environmental matrices were explored by spiking nanoplastics in various organic matter suspensions (i.e., algae, soil natural organic matter, and soil humic acid) and analyzing an environmental suspension of nanoplastics. While a rapid polypropylene nanoplastics identification was validated, polystyrene nanoplastics require preliminary treatment. The strategies presented herein open new possibilities for the detection/identification of nanoplastics in environmental matrices such as soil, dust, and biota.

Material Analysis and a Visual Guide of Degradation Phenomena in Historical Synthetic Polymers as Tools to Follow Ageing Processes in Industrial Heritage Collections.

Identifying the most vulnerable plastics and monitoring their deterioration is one of the main problems within heritage collections with historical synthetic polymers. Gathering and interpreting data about material and degradation phenomena in a collection reveals its conservation needs. A systematic survey of the collection can help towards this purpose. Surveys aiming at inspecting and documenting damages rely on several tools in order to fulfill their purpose. Firstly, objective descriptions of the damages that may appear, and secondly, the means of acquiring and interpreting material information. To address these needs, this article presents (a) a visual damage catalogue of degradation phenomena in plastic and rubber materials, and (b) the implementation of Fourier-transform infrared spectroscopy (FTIR) and pyrolysis-gas chromatography-mass spectrometry (py-GCMS) for the identification of analytically challenging rubber materials and of blooming phenomena. The damage catalogue is based solely on visual and olfactory signs, so that the assessment is independent of possible causes of damages and underlying processes, with the purpose of allowing objectivity to prime over interpretation. The limitations of the use of FTIR in the identification of heavily compounded rubbers in museum surveys is highlighted, and examples are presented. The use of py-GCMS on these cases conveniently allowed the identification of the constituting monomers of several rubber materials where FTIR could not provide a univocal classification of the material present. The study of several cases of blooming allowed the identification of diverse compositions and origins, showing that the description of a degradation phenomenon is only the first step towards its understanding. Unveiling the nature of a particular case of blooming is particularly critical when conservation treatments, such as the removal of a (potentially protecting) layer, are planned. For this purpose, attenuated total reflection-FTIR (ATR-FTIR) as a surface technique was particularly useful.

Nanoplastic occurrence in a soil amended with plastic debris.

While several studies have investigated the potential impact of nanoplastics, proof of their occurrence in our global environment has not yet been demonstrated. In the present work, by developing an innovative analytical strategy, the presence of nanoplastics in soil was identified for the first time. Our results demonstrate the presence of nanoplastics with a size ranging from 20 to 150 nm and covering three of the most common plastic families: polyethylene, polystyrene and polyvinyl chloride. Given the amount of organic matter in the soil matrix, the discrimination and identification of large nanoplastic aggregates are challenging. However, we provided an innovative methodology to circumvent the organic matter impact on nanoplastic detection by coupling size fractionation to molecular analysis of plastics. While photodegradation has been considered the principal formation pathway of nanoplastics in the environment, this study provides evidence, for the first time, that plastic degradation and nanoplastic production can, however, occur in the soil matrix. Moreover, by providing an innovative and simple extraction/analysis method, this study paves the way to further studies, notably regarding nanoplastic environmental fate and impacts.

Comparison of µ-ATR-FTIR spectroscopy and py-GCMS as identification tools for microplastic particles and fibers isolated from river sediments.

In recent years, many studies on the analysis of microplastics (MP) in environmental samples have been published. These studies are hardly comparable due to different sampling, sample preparation, as well as identification and quantification techniques. Here, MP identification is one of the crucial pitfalls. Visual identification approaches using morphological criteria alone often lead to significant errors, being especially true for MP fibers. Reliable, chemical structure-based identification methods are indispensable. In this context, the frequently used vibrational spectroscopic techniques but also thermoanalytical methods are established. However, no critical comparison of these fundamentally different approaches has ever been carried out with regard to analyzing MP in environmental samples. In this blind study, we investigated 27 single MP particles and fibers of unknown material isolated from river sediments. Successively micro-attenuated total reflection Fourier transform infrared spectroscopy (µ-ATR-FTIR) and pyrolysis gas chromatography-mass spectrometry (py-GCMS) in combination with thermochemolysis were applied. Both methods differentiated between plastic vs. non-plastic in the same way in 26 cases, with 19 particles and fibers (22 after re-evaluation) identified as the same polymer type. To illustrate the different approaches and emphasize the complementarity of their information content, we exemplarily provide a detailed comparison of four particles and three fibers and a critical discussion of advantages and disadvantages of both methods.

Examination of the chemical changes in cured phenol-formaldehyde resins during storage.

Chemical changes occurring within cured phenol-formaldehyde resins (resite and novolak type) during their storage were investigated by FT-NIR, py-GCMS and inverse gas chromatography. It was shown that a mixture of resite with novolak was less stable than resite or novolak itself as regards bulk properties. This aging phenomenon is mainly due to reaction of ammonia (product of hexa decomposition) with CH2OH groups present in resite. FT-NIR technique seems to be the least sensitive method for assessment chemical changes occurring during cured resins storage. Applications of py-GCMS and IGC method made able to indicate that more significant changes were for bulk samples (py-GCMS results) than on their surface (IGC results).