Assisted by multidimensional data analysis, chemical recycling methods for waste generated by the renewable energy sector in the context of the circular economy.

An in-depth study of the oxidative liquefaction process has been provided to degrade the polymeric waste from personal protective equipment (PPEs) and wind turbine blades (WTBs). Thermogravimetric investigations demonstrate that WTBs have three prominent peaks throughout the degradation, whereas PPEs display solitary peak features. Experiments are carried out employing specific experimental design approaches, namely the Central Composite Face-Centered Plan (CCF) for WTBs and the Central Composition Design with Fractional Factorial Design for PPEs in a batch-type reactor at temperature ranges of 250–350 °C, pressures of 20–40 bar, residence times of 30–90 min, H2O2 concentrations of 15–45 %, and waste/liquid ratios of 5–25 % for WTBs. These values were 200–300 °C, 30 bar, 45 min, 30–60 % and 5–7 % for PPE. A detailed comparison has been provided in the context of total polymer degradation (TPD) for PPE and WTBs. Liquid products from both types of wastes after the oxidative liquefaction process are subjected to gas chromatography with flame ionization detection (GC-FID) to identify the existence of oxygenated chemical compounds (OCCs). For WTBs, TPD was 20–49 % and this value was 55–96 % for PPE while the OCC yield for WTBs (36.31 g/kg - 210.59 g/kg) and PPEs (39.93 g/kg - 212.66 g/kg) was also calculated. Detailed optimization of experimental plans was carried out by performing the analysis of variance (ANOVA) and optimization goals were maximum TPD and OCCs yields against the minimum energy consumption, though a considerable amount of complex polymer waste can be reduced and high concentrations of OCC can be achieved, which could be applied for commercial and environmental benefits.

In pursuit of sustainable development, recycling composite waste is a crucial challenge as well as an opportunity to support the progress towards eco-friendly materials management and circular economy practices. The current study brings together two modern recycling techniques solvolysis and oxidative liquefaction to recycle five types of composite waste materials including wind turbine blades (WTBs), composite pipes, personal protective equipment (PPEs) used in the medical sector, photovoltaic (PV) panels and municipal solid waste (MSW). Following a well-structured experimental design for each type of waste the solvolysis was performed at a temperature range of 100–190 °C, process time within the range of 1–3 h, and catalyst (TBD) concentration within the range of 0.015–0.025 mol, end with ethylene glycol and 1-methyl-2-pyrrolidinone in a 1:1 M ratio, while depending on the material evaluated, the oxidative liquefaction process was conducted at temperatures between 250 and 350 °C for WTB and between 200 and 300 °C for PPE, MSW, and PV. Oxidant concentrations, reaction time and pressure (15–45%, 30–90 min, 20–40 bar for WTBs, 30–60%, 45 min, 30 bar for remaining waste types) were studied in addition to highly variant waste-to-liquid ratio from 5 to 25% for WTB, 3–7% for PPE and MSW, and 12.5–37.5 for PV. Prior to experimental investigation, surface morphologies and chemical studies of the waste material were performed by scanning electron microscope (SEM) and Fourier transform infrared FT-IR spectroscopy, while after experimentation total polymer degradation (TPD) was calculated and liquid products were analysed through gas chromatography with flame ionisation detection (GC-FID). Following the solvolysis, 50–60% TPD was obtained, allowing for the recovery of glass fibres (GF) with average lengths of 50–60 mm and a maximum length of 650 mm. This allowed for the recovery of GFs with average lengths of 50–60 mm and a maximum length of 650 mm. In the case of oxidative liquefaction, total polymer degradation of 72–100%, 52–100% and 55–100% was achieved, depending on the investigated waste, i.e. WTB, PPE and MSW, respectively. The yield of oxygenated chemical compounds depended upon the types and composition of waste, but acetic acid was the main acid while WTB, PPE, and MSW, the liquid samples contained phenol also. Involved chemistry and possible degradation pathways of complex composite wastes are discussed in detail to enhance the recycling process and material recovery.

Various waste streams including municipal solid waste (MSW), polymer waste from personal protective equipment (PPE) used in medical fields, and composite waste from wind turbine blades (WTBs) demand modern waste management and recycling approaches. Ultimate and proximate analysis of mentioned samples revealed a higher content of carbon—28.2 ± 8.0, 80.1 ± 2.3, and 50.3 ± 2.3, respectively—exhibiting sufficient potential to be converted into secondary carbon-based compounds. For this purpose, oxidative liquefaction of selected waste materials was carried out following a detailed experimental plan, a centred composite design for WTBs, and a central composite face-centred plan for MSW and PPEs. Temperature, pressure, oxidant concentration, reaction time, and waste-to-liquid ratio were the parameters of key interest, and their values were tested at a range of 200–350 °C, 20–40 bar, 15–60%, 30–90 min, and 3–25%, respectively, depending upon the type of waste. As a result, total polymer degradation (TPD) was recorded for three types of waste and the results were satisfactory, encouraging the decomposition of primary waste in liquid oxygenated chemical compounds (OCCs). Gas Chromatography with Flame Ionisation Detection (GC-FID) helped us quantify the number of OCCs for each waste sample. Energy consumption during the process was also recorded and optimisation of the experimental plan based on maximum TPD and OCCs yields against the minimum energy consumption was performed to make the process tech-economic.

Quantitative methods are detailed for determination of ethyl carbamate in distilled alcoholic beverages by capillary gas chromatography with flame ionization detection (GC/FID) and by packed-column gas chromatography/mass spectrometry (GC/MS) using selected ion monitoring. Five g samples of distillate of known ethanol concentration are diluted with water to 25% ethanol (v/v), washed with petroleum ether, and extracted with dichloromethane prior to GC/FID or GC/MS analysis. As necessary, sample extracts that exhibit GC/FID interference are passed through alumina for additional cleanup. When internal standards (tert-butyl carbamate and n-butyl carbamate for GC/FID, or ethyl 13C-15N-carbamate for GC/MS) were used for quantitation, the limit of detection for ethyl carbamate was in the range of 5-25 ppb. Coefficients of variation ranged from 3.5 to 6.0% for GC/FID determinations, and from 1.4 to 3.2% for GC/MS. Correlation between methods for 22 random distillate samples ranging in concentration from approximately 40 to 800 ppb gave a correlation coefficient (r) of 0.996.

The triacylglycerol (TAG) to sterol (ST) ratio, which has been used to determine the condition index in marine species, has regularly been measured via thin‐layer chromatography with flame ionization detection (TLC/FID) using the Chromarod‐Iatroscan system. However, this method is labor intensive, requires long analysis times, and has a detection limit of ~50 ng. For the determination of lipids in very small samples such as individual fish larvae, short‐column gas chromatography with flame ionization detection (GC/FID) provides an excellent alternative to Iatroscan TLC/FID, owing to its lower detection limit (~1 ng for high‐molecular‐weight TAG and ~0.1 ng for lower‐molecular‐weight species). As well, GC/FID individually profiles lipids based on their carbon number, whereas TLC/FID groups lipids according to their lipid class. Here we describe a method for the determination of neutral lipids from individual Cyclopterus lumpus (lumpfish) and Myoxocephalus scorpius (short‐horn sculpin) larvae using short‐column GC/FID. By using an internal standard and applying weight correction factors, ST and TAG can be accurately and precisely measured. The results reveal that there were no significant differences between GC/FID and TLC/FID in the quantification of TAG or ST in individual fish larvae (P > 0.05); however, GC/FID is more sensitive, precise, rapid, and cost‐efficient.

Metabolic fingerprinting of hard and semi-hard natural cheeses using gas chromatography with flame ionization detector for practical sensory prediction modeling

Considering the increasing number of low cost vegetable oil product adulterations, it is necessary to assess the authenticity of the lipid sources used in the dog food manufacture, consequently different brands and classifications of feed were analyzed to verify the product authenticity by gas chromatography (GC) with flame ionization detector (FID) and by electrospray ionization mass spectrometry (ESI-MS). Fatty acid (FA) composition analysis was performed to compare the FAs amount in samples with the respective guarantee levels stated by the manufacturers on its product label. Gas chromatography with flame ionization detector (GC-FID) results for omega-3 and 6 percentages are within the limits presented by each manufacturer, while the timnodonic + cervonic acids amount information presented on feed sample labels is not in accordance with GC-FID results. Consequently, the samples were analyzed by ESI-MS, the results exposed the chicken oil presence in the feed and eicosapentaenoic (EPA) + docosahexaenoic (DHA) acids absence, since no lipid profiles similar to fish oils or triacylglycerols (TAGs) containing these two FAs were found. Thus, the information presented on labels are in disagreement with the results obtained both by GC-FID FA composition analysis and by ESI-MS lipid profile analysis. Principal component analysis (PCA) confirmed that the main contribution was from FAs found by GC-FID.

Rapid analysis of eucalyptus oil adulteration in Moroccan rosemary essential oil via GC-FID and mid-infrared spectroscopy

An evaluation of qH NMR: A complementary approach to GC-FID for quantification of Thymol and trans-Anethole in essential oils and supplements

Ambient air commonly contains carbon dioxide at concentrations greater than 400µmolmol-1 and methane at ~ 2000nmolmol-1; non-methane hydrocarbons are also widespread in the atmosphere at much lower concentrations. For quantification of various carbon-containing compounds in typical analytical instrument, corresponding number of reference materials are required. Therefore, the development of a method that uses a single reference material applicable to air monitoring is desired. Here, we examined a post-column reaction system combined with a gas chromatograph equipped with a flame ionization detector (FID), which involves oxidation and reduction processes after separation. To determine various carbon-containing gases by post-column reaction gas chromatography with FID (GC-r-FID) using a single reference, it is necessary to confirm a good linearity of the response with carbon concentrations originating from various carbon-containing gases. When mixtures of carbon-containing gases at three different concentrations and the calibration curve of the FID response with the concentration converted into methane were used, a single linear calibration curve (correlation coefficient > 0.9999, 18 points) was obtained over four orders of magnitudes (to ~ 5000µmolmol-1 as methane). The applicability of GC-r-FID was confirmed by determining carbon-containing gases in air and gas seeped from the seafloor samples. Because the results were comparable to those obtained by conventional GC-FID and GC-thermal conductivity detector, typically GC-r-FID with a single reference gas should be suitable for air monitoring.

The monosaccharide composition is one of the crucial factors affecting the bioactivity of exopolysaccharide (EPS) in Cordyceps species. Therefore, many scientists have studied, analyzed monosaccharide composition and structure of EPS from Cordyceps species, especially Ophiocordyceps sinensis (O. sinensis). This study aimed to compare hydrochloric acid (HCl) with trifluoroacetic acid (TFA) in the EPS hydrolysis process in monosaccharide composition analysis by Gas Chromatography with Flame-Ionization Detection (GC-FID). The hydrolysis is a crucial step in forming the acetyl derivative, which helps the GC-FID technique to have good results in monosaccharide composition analysis. The results showed that hydrolysis with HCl gave a higher hydrolysis efficiency and was more suitable than hydrolysis by TFA in pretreatment to EPS for GC-FID. Hydrolysis results were analyzed through thin-layer chromatography and high-performance liquid chromatography (HPLC), then Acetyl derivatives were produced and finally analyzed by GC-FID to determine the monosaccharide composition of EPS. For EPS hydrolyzed by HCl, the analytical results presented that this sample had 6 kinds of monosaccharides, including rhamnose, arabinose, xylose, mannose, glucose, and galactose; the most monosaccharide was glucose. The EPS hydrolyzed by TFA only detected three kinds of monosaccharides, including mannose, arabinose, and galactose, mainly mannose. The study has set a foundation for further analysis of monosaccharide composition and structure of EPS from O. sinensis.

The traditional linear economy has created unstainable development. A circular economy (CE) is considered as a crucial means and has been adapted by many governments to achieve sustainable development goals. By narrative literature review, this article aims to discuss the concepts of linear and circular economies and CE models, examine countries’ CE development experiences, and make recommendations for successfully adapting a CE. The findings show that a CE is different from a linear one in terms of the step plan, focus, system boundaries, reuse, and business models. The CE model includes slowing and closing resource loops and a narrowing of resource flows and is based on the foundation of renewable and non-toxic resources as well as through long-lasting design, and reducing, maintaining, repairing, reusing, remanufacturing, refurbishing, recovering, and recycling. Many countries around the world have adapted a CE model with different circularity levels with the main focus to reduce waste. The paper also recommends that a CE should be percieved as the central point of socio-economic development programs and policies that must address the full cycle, from product design to production processes, consumption, and recycling rather than having only a waste reduction focus. Producers should use a CE framework as the basis for product design, manufacturing, and recycling strategies. Consumers should change their perception of CE and adjust their behaviors towards making decisions to buy and consume toward circularity. Also, there is a need to change the perceptions of policy makers and other stakeholders on the CE concepts and framework.

Oxidative liquefaction as an alternative method of recycling and the pyrolysis kinetics of wind turbine blades

Groundwater contamination by polycyclic aromatic hydrocarbons (PAH) may pose a risk to human health, as these compounds are considered to be highly toxic, carcinogenic and/or mutagenic and bioaccumulative. The aim of this study was to evaluate and determine PAH levels in groundwater samples collected from tubular wells in a city of northern Brazil by gas chromatography with flame ionization detector (GC-FID) used by the population for consumption. Sample pre-treatment using solid-phase extraction cartridges was performed in order to promote an enrichment of the PAH fraction of interest and to remove interferences from the matrix to further determine PAH in samples by GC-FID. The results obtained showed that all groundwater samples studied presented PAH levels lower than maximum values allowed by MS 2914/2011 and CONAMA 396/2008. The developed procedure is characterized by low limits of detection and quantification, equal to 0.024–0.113 µg L−1 and 0.079–0.378 μg L−1, respectively, good linearity (r2 > 0.99). The recoveries obtained for 16 PAH by the addition and recovery method ranged from 85.4 to 105.7% with good precision (RSD < 5.0%). The results of this study showed that the method developed is fast, accurate and robust with high efficiency for identification and determination of 16 PAH in groundwater samples.

Introduction: The detection of methanol in alcoholic beverages represents a critical public health issue, particularly in light of the recent outbreak of poisonings in Brazil, which registered 58 confirmed cases and 15 deaths through October 2025. Methanol's toxicity, with an estimated lethal dose ranging from 0.5 to 1.5 g/kg, requires reliable analytical methods for health surveillance. Brazilian legislation establishes a maximum limit of 20 mg/100 mL of anhydrous alcohol; however, the need for accessible screening methods in field settings remains an important challenge. Objective: To critically compare three analytical methods for methanol determination: classical qualitative methods (Lucas Test and dichromate/Schiff), Brazilian colorimetric method, and gas chromatography with flame ionization detector (GC-FID), evaluating their performance and applicability in resource-limited contexts. Methods: Theoretical-comparative approach through critical analysis of specialized literature and normative technical documentation. Methods were evaluated according to: operational principle, sensitivity (LOD/LOQ), selectivity, operational complexity, analysis time, and practical applicability. Results: The Lucas Test is not applicable for methanol detection. Colorimetric methods showed moderate sensitivity (LOD ~20-160 mg/100 mL), a 10-30-minute execution time, low operational complexity, and excellent portability. The Brazilian method presented chemical equivalence with international standards, differing only in the type of reading performed. GC-FID has shown superior sensitivity (LOD ≤ 1 mg/100 mL) and high specificity, but it requires extended time (~45-60 minutes), complex laboratory infrastructure, and specialized operators. Sugars interfere with colorimetric methods. Conclusions: The methods are complementary within a hierarchical system. Colorimetric methods enable rapid field screening, while GC-FID serves as the confirmatory method for forensic analyses. We recommend implementing integrated protocols that combine in situ colorimetric screening with GC-FID confirmation in accredited laboratories for effective health surveillance.