Search Results (154)

Every year, a large amount of antibiotics enter aquatic environments globally through discharging of pharmaceutical wastewater and domestic sewage, emissions from agriculture, and livestock, posing a severe threat to ecosystems and human health. Therefore, it is essential to develop efficient adsorption materials for rapid removal of antibiotics in water. In this study, abundant and renewable wetland plants (lotus leaves, Arundo donax, and canna lilies) were utilized as raw materials to prepare biochar through slow pyrolysis combined with KOH chemical activation. The prepared biochar was employed to adsorb typical tetracycline (TC) antibiotics (TC-HCl, CTC-HCl, OTC-HCl) from water. The results showed that the optimum biochar (LBC-600 (1:3)) was prepared at a pyrolysis temperature of 600 °C with the mass ratio of KOH to lotus leaf of 1:3. The optimum pH for the adsorption of the three antibiotics were 5, 4, and 3, respectively. The highest adsorption rates reached 93.32%, 81.44%, and 83.76% for TC-HCl, CTC-HCl, and OTC-HCl with 0.6 g/L of biochar, respectively. At an initial antibiotic concentration of 80 mg·L⁻¹, the maximum adsorption capacities achieved 40.17, 27.76, and 24.6 mg·g⁻¹ for TC-HCl, CTC-HCl, and OTC-HCl, respectively. The adsorption process conformed to the pseudo-second-order kinetic and Langmuir isotherm models, indicating that it was a spontaneous endothermic process and primarily involved monolayer chemical adsorption. This study transformed wetland plant waste into adsorbent and applied it for antibiotic removal, providing a valuable resource utilization strategy and technical support for recycling wetland plant residues and antibiotic removal from water environments. Full article

Accurate quantification of soil organic matter (SOM) is crucial for improving soil fertility and maintaining ecosystem health. The content of SOM affects soil nutrient availability and is closely linked to the global carbon cycle. The use of an electronic nose to detect SOM contents has the advantages of rapidity, accuracy, and low pollution to the environment. This study proposes a method for obtaining SOM contents via pyrolysis coupled with an artificial olfaction system. To improve the accuracy of SOM content determination, the effects of three parameters (pyrolysis temperature, pyrolysis time, and soil sample mass) related to the pyrolysis process on the distinguishability of pyrolysis gases were investigated. Firstly, single-factor experiments were conducted to determine the optimal values of three parameters that can improve the differentiation of pyrolysis gases. Secondly, a regression model based on the Box–Behnken experiment was established to analyze the interrelationships between the three parameters and the discrete ratio. The experimental results showed that the three parameters exerted significant influences on the discrete ratio, with pyrolysis time having the greatest impact, followed by soil sample mass and pyrolysis temperature. The optimal discrimination and minimal dispersion ratio of the pyrolysis gases were achieved at a pyrolysis temperature of 384 °C, with a pyrolysis time of 2 min 41 s and a soil sample mass of 1.68 g. Finally, the Back-Propagation Neural Network (BPNN) and Partial Least-Squares Regression (PLSR) algorithms were used to establish an SOM prediction model after obtaining soil pyrolysis gases under the optimal combination of pyrolysis parameters. The experimental results demonstrated that the SOM prediction model based on PLSR achieved the best accuracy and the highest generalization capability, with R² > 0.85 and RMSE < 7.21. This study could provide a theoretical basis for the prediction of SOM contents via pyrolysis coupled with an artificial olfaction system. Full article

Currently, the Longmaxi shale in the Sichuan Basin is the most successful stratum of shale gas production in China. However, because Longmaxi shale mostly has high over-maturity, a low-maturity sample cannot be obtained for gas generation thermal simulations, and as a result, a gas generation model has not yet been established for it. Therefore, models of other shales are usually used to calculate the amount of gas generated from Longmaxi shale, but they may produce inaccurate results. In this study, a Longmaxi shale sample with an equivalent vitrinite reflectance calculated from Raman spectroscopy (EqVR_o) of 1.26% was obtained from Well Yucan 1 in the Chengkou area, northeast Sichuan Province. This Longmaxi shale may have the lowest maturity in nature. Pyrolysis simulations based on gold tubes were performed on this sample, and the gas generation line was obtained. The amount of gas generated during the low-maturity stage was compensated by referring to gas generation data obtained from Lower Silurian black shale in western Lithuania. Thus, a gas generation model of the Longmaxi shale was built. The model showed that the gas generation process of Longmaxi shale could be divided into three stages: (1) First, there is the quick generation stage (EqVR_o 0.5–3.0%), where hydrocarbon gases were generated quickly and constantly, and the generation rate was steady. A maximum of 458 mL/g TOC was reached at a maturity of 3.0% EqVR_o. (2) Second, there is the stable stage (EqVR_o 3.0–3.25%), where the amount of generated gas reached a plateau of 453–458 mL/g TOC. (3) Third, there is the rapid descent stage (EqVR_o > 3.25%), where the amount of generated gas started to decrease, and it was 393 mL/g TOC at an EqVR_o of 3.34%. This model allows us to more accurately calculate the amount of gas generated from the Longmaxi shale in the Sichuan Basin. Full article

Rapid economic growth has led to an increase in the use of multilayer plastic packaging, which involves complex polymer compositions and hinders recycling. This study investigated the catalytic pyrolysis of plastic packaging waste in a 3000 cm³ semibatch reactor, aiming to optimize kerosene-like hydrocarbon production. The temperature (420–500 °C), N₂ flow rate (25–125 mL/min), and catalyst loading (5–20 wt.%) were examined individually and in combination with activated carbon and an Fe-doped dolomite (Fe/DM) catalyst. Central composite design (CCD) and response surface methodology (RSM) were used to identify the optimal conditions and synergistic effects. Pyrolysis product analysis involved simulation distillation gas chromatography (Sim-DGC), gas chromatography/mass spectrometry (GC/MS), and Fourier transform infrared (FT-IR) spectroscopy. The optimal conditions (440 °C, 50 mL/min N₂ flow, catalyst loading of 10 wt.% using a 5 wt.% Fe-doped dolomite-activated carbon 0.6:0.4 mass/molar ratio) yielded the highest pyrolysis oil (79.6 ± 0.35 wt.%) and kerosene-like fraction (22.3 ± 0.22 wt.%). The positive synergistic effect of Fe/DM and activated carbon (0.6:0.4) enhanced the catalytic activity, promoting long-chain polymer degradation into mid-range hydrocarbons, with secondary cracking yielding smaller hydrocarbons. The pore structure and acid sites of the catalyst improved the conversion of intermediate hydrocarbons into aliphatic compounds (C₅–C₁₅), increasing kerosene-like hydrocarbon production. Full article

Valorizing agro-industrial waste into functional materials for environmental remediation and resource recovery is essential for advancing circular economy models. This study presents a novel closed-loop strategy to convert annatto (Bixa orellana) seed residues into biochar for phosphate recovery from aqueous solutions and real agro-industrial wastewater. A novel ternary modification with Fe, Zn, and Mn metals was applied to enhance the phosphate adsorption performance of the biochar. Materials were synthesized via pyrolysis at 600 °C and 700 °C, with ABC-M700 exhibiting the highest performance. Comprehensive characterization (FTIR, SEM–EDS, and XRF) confirmed the successful incorporation of metal (oxy)hydroxide functional groups, which facilitated phosphate binding. Adsorption studies revealed that ABC-M700 achieved a maximum phosphate removal capacity of 6.19 mg·g⁻¹, representing a 955% increase compared to unmodified ABC-N700 (0.59 mg·g⁻¹), and a 31% increase relative to ABC-M600 (4.73 mg·g⁻¹). Physicochemical characterization indicated increased surface area, well-developed mesoporosity, and the formation of metal (oxy)hydroxide functionalities. ABC-M700 achieved a maximum adsorption capacity of 73.22 mg·g⁻¹ and rapid kinetics, removing 95% of phosphate within 10 min and reaching equilibrium at 30 min. The material exhibited notable pH flexibility, with optimal performance in the range of pH 6–7. Performance evaluations using real wastewater from the same agro-industry confirmed its high selectivity, achieving 80% phosphate removal efficiency despite the presence of competing ions and organic matter. Phosphate fractionation revealed that 78% of adsorbed phosphate was retained in stable, metal-associated fractions. Although the material showed limited reusability, it holds potential for integration into nutrient recycling strategies as a slow-release fertilizer. These findings demonstrate a low-cost, waste-derived adsorbent with strong implications for circular economy applications and sustainable agro-industrial wastewater treatment. This study establishes a scalable model for agro-industries that not only reduces environmental impact but also addresses phosphorus scarcity and promotes resource-efficient waste management. Full article

The insulation layer of flame-retardant cables plays a critical role in mitigating fire hazards by influencing toxic gas emissions and the accuracy of fire modeling. This study systematically explores the pyrolysis kinetics and volatile gas evolution of flame-retardant polyvinyl chloride (PVC) and polyethylene (PE) insulation materials using advanced TG-FTIR-GC/MS techniques. Distinct pyrolysis stages were identified through thermogravimetric analysis (TGA) at heating rates of 10–40 K/min, while the KAS model-free method and Málek fitting function quantified activation energies and reaction mechanisms. Results revealed that flame-retardant PVC undergoes two major stages: (1) dehydrochlorination, characterized by the rapid release of HCl and low activation energy, and (2) main-chain scission, producing aromatic compounds that contribute to fire toxicity. In contrast, flame-retardant PE demonstrates a more stable pyrolysis process dominated by random chain scission and the formation of a dense char layer, significantly enhancing its flame-retardant performance. FTIR and GC/MS analyses further highlighted distinct gas evolution behaviors: PVC primarily generates HCl and aromatic hydrocarbons, whereas PE releases olefins and alkanes with significantly lower toxicity. Additionally, the application of a classification and regression tree (CART) model accurately predicted mass loss behavior under various heating rates, achieving exceptional fitting accuracy (R² > 0.98). This study provides critical insights into the pyrolysis mechanisms of flame-retardant cable insulation and offers a robust data framework for optimizing fire modeling and improving material design. Full article

Finding alternatives to platinum that exhibit high activity, stability, and abundant reserves as oxygen reduction electrocatalysts is crucial for the advancement of fuel cells. In this study, we first mixed FeCl₂·4H₂O, 1,10-phenanthroline, and Vulcan XC-72, followed by pyrolysis in a nitrogen atmosphere, to obtain FeNC. Subsequently, we combined FeNC with MXene produce FeNC/MXene composites. The FeNC/MXene catalyst achieved a half-wave potential of 0.857 V in an alkaline medium, exhibiting better oxygen reduction reaction (ORR) activity and durability than commercial Pt/C catalysts. The layered structure of MXene endows the material with a high specific surface area and facilitates efficient electron transfer pathways, thereby promoting rapid charge transfer and material diffusion. The cleavage of Ti-C bonds in Ti₃C₂ at elevated temperatures results in the transformation of MXene into TiO₂, where the coexistence of anatase and rutile phases generates a synergistic effect that enhances both the mass transfer rate and the electrical conductivity of the catalytic layer. Additionally, the unique electronic structure of the FeN_x sites simultaneously optimizes electrocatalytic activity and stability. Leveraging these structural advantages, the FeNC/MXene composite catalysts demonstrate exceptional catalytic activity and long-term stability in oxygen reduction reactions. Full article

Cyclohexane-containing semi-aromatic polyamides (c-SaPA) exhibit excellent comprehensive properties. Existing studies predominantly focus on synthesis and modification, while fundamental investigations into pyrolysis mechanisms remain limited, which restricts the development of advanced materials for high-performance applications such as automotive and energy systems. This study employs Reactive Force Field Molecular Dynamics (ReaxFF-MD) simulations to establish a pyrolysis model for poly(terephthaloyl-hexahydro-m-xylylenediamine) (PHXDT), systematically probing its pyrolysis kinetics and evolutionary pathways under elevated temperatures. The simulation results reveal an activation energy of 107.55 kJ/mol and a pre-exponential factor of 9.64 × 10¹³ s⁻¹ for the pyrolysis process. The primary decomposition pathway involves three distinct stages. The first is initial backbone scission generating macromolecular fragments, followed by secondary fragmentation that preferentially occurs at short-chain hydrocarbon formation sites alongside radical recombination. Ultimately, the process progresses to deep dehydrogenation, carbonization, and heteroatom elimination through sequential reaction steps. Mechanistic analysis identifies multi-pathway pyrolysis involving carboxyl/amide bond cleavage and radical-mediated transformations (N-C-O, C-C-O, OH· and H·), yielding primary products including H₂, CO, H₂O, CH₃N, C₂H₂, and C₂H₄. Crucially, the cyclohexane structure demonstrates preferential participation in dehydrogenation and hydrogen transfer reactions due to its conformational dynamic instability and low bond dissociation energy, significantly accelerating the rapid generation of small molecules like H₂. Full article

With the rapid growth of the global population, increasing per capita energy demands, and waste generation, the need for innovative strategies to mitigate greenhouse gas emissions and effective waste management has become paramount. Pyrolysis, a thermochemical conversion process, facilitates the transformation of diverse biomass feedstocks, including agricultural biomass, forestry waste, and other carbonaceous wastes, into valuable biofuels such as bio-oil, biochar, and producer gas. The article reviews the benefits of pyrolysis as an effective and scalable technique for biofuel production from waste biomass. The review describes the different types of pyrolysis processes, such as slow, intermediate, fast, and catalytic, focusing on the effects of process parameters like temperature, heating rate, and residence time on biofuel yields and properties. The review also highlights the configurations and operating principles of different reactors used for pyrolysis, such as fixed bed, fluidized bed, entrained flow, plasma system, and microwaves. The review examines the factors affecting reactor performance, including energy consumption and feedstock attributes while highlighting the necessity of optimizing these systems to improve sustainability and economic feasibility in pyrolysis processes. The diverse value-added applications of biochar, bio-oil, and producer gas obtained from biomass pyrolysis are also discussed. Full article

In this study, we use coal as a carbon source from Zhangjiamao and doped with different nitrogen sources for co-pyrolysis. Nitrogen-rich tar was successfully prepared, and the content and variety were also increased. From the elemental analysis, the nitrogen content of all the tars was significantly enhanced, among which the nitrogen content of the tars after co-pyrolysis with melamine was enhanced by 5.21%, and the nitrogen content of coke was enhanced by 10.87%. According to the GC/MS results, it was found that the nitrogen compounds in the tar after full pyrolysis were richer and more abundant than those in Py-GC/MS. For the free radical reaction, the reaction process is extremely rapid, and the ¹⁵N substitution product after isotope labeling was successfully captured by adding ¹⁵NH₄Cl for isotope labeling, which can be more intuitively and accurately illustrated from the m/z change. Among them, 26 nitrogen-containing compounds were screened out, which accounted for 66.28% of the content, and they were categorized. It was found that the five-membered nitrogen heterocycles were the most abundant, accounting for 34.88%. In addition, five other nitrogen-containing compounds containing different functional groups and the tar from the co-pyrolysis of tar-rich coal were also analyzed by GC/MS, among which the tar from melamine had the highest content of nitrogen-containing compounds, with 70.48%. Finally, the functional groups of nitrogen-containing compounds were further analyzed by XPS and FTIR, and the results were consistent with those of GC/MS analysis. In this paper, nitrogen-rich tar was prepared by co-pyrolysis of tar-rich coal and nitrogen compounds. This achievement provides a valuable reference for the high-value utilization of coal tar. Full article

The stabilization and upgrading of biomass and waste-derived pyrolysis oils requires development of reliable, active and low-cost upgrading catalysts. Basic natural materials can act as such catalysts and convert reactive oxygenates present in biomass pyrolysis oils. The conversion of furfural as a model compound has been conducted in an autoclave reactor at 200 °C to 300 °C using different calcium-based materials. CaCO₃, Ca(OH)₂, CaO, cement raw meal (CRM) and calcined cement raw meal (cCRM) were screened for their catalytic activity and characterized using X-ray powder diffraction (XRD) and X-ray fluorescence (XRF), nitrogen physisorption, carbon dioxide temperature programmed desorption (CO₂-TPD) and thermogravimetric analysis (TGA). CaCO₃ and CRM had low basicity and showed no catalytic activity at 200 to 300 °C. Notably, 90% conversion of furfural was achieved at 200 °C using Ca(OH)₂ with products being mostly furfural di- and trimers. For the basic CaO and cCRM, a temperature of 250 °C or above caused rapid polymerization of furfural. The proposed mechanism follows the Cannizzaro reaction of furfural, catalyzed by basic sites, polymerization of furfuryl alcohol, decarboxylation of furoic acid and decarbonylation of furfural, releasing CO, CO₂ and H₂O. Calcined cement raw meal showed the most promise for application as low-cost, sacrificial, basic catalyst. Full article

The rapid increase in plastic production and consumption has intensified research into human exposure to micro- and nanoplastics (MNPs) and their health effects. This study quantitatively assessed MNP internal exposure levels in non-invasive human samples, focusing on the four most common types of MNPs (≥300 nm): polyethylene terephthalate (PET), polypropylene (PP), low-density polyethylene (LDPE), and polystyrene (PS). Urine samples from 18 volunteers (4 males, 14 females) were analyzed using pyrolysis–gas chromatography–mass spectrometry (Py-GC/MS) with P(E-¹³C₂) as an internal standard. The study developed a straightforward yet effective analytical approach for quantifying MNPs in biological fluids. MNPs were detected in all urine samples, with concentrations ranging from 0.098 to 0.986 μg/mL and an average concentration of 0.268 ± 0.235 μg/mL. LDPE, 0.074 μg/mL (interquartile range: 0.030–0.243 μg/mL), was the most abundant polymer, accounting for 67.72% of the total MNPs, followed by PS at 21.17%, while PP and PET accounted for 7.06% and 4.05%, respectively. The results also suggest that drinking water type may serve as a distinct source of MNPs in urine. This study provides novel evidence on MNP (≥300 nm) internal exposure in humans and the influence of drinking habits, highlighting the application prospects of this method in assessing the potential health risks of MNPs. Full article

The present study aims to prepare a composite via pyrolysis, based on sodium alginate (SA) and a natural clay collected from the eastern region of Morocco, specifically the OUJDA area (C.O.R), for use in the disposal process of emerging pharmaceuticals. The strategy of rapid microwave heating followed by nitrogen calcination at 500 °C was successfully applied to produce the pyrolyzed carbonaceous materials. The removal of paracetamol (PCT) by adsorption on the carbonaceous clay (ca-C.O.R) composite was investigated to determine the effect of operating parameters (initial contaminant concentration, contact time, pH, and temperature) on the efficiency of PCT removal. The nanocomposite was analyzed using various techniques, including the nitrogen gas adsorption–desorption isothermal curve, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Three models were used to describe the kinetic adsorption, and it was found that the experimental kinetic data fit well with a pseudo-second-order kinetic model with a coefficient of determination R² close to one, a nonlinear chi-square value close to zero, and a reduced root mean square error RMSE (R² → 1, X² → 0 and lower RMSE). The adsorption was best described by the Sips isotherm. The ca-C.O.R composite achieved a PCT removal efficiency of 91% and a maximum adsorption capacity of 122 mg·g⁻¹ improving on the performance of previous work. Furthermore, the variation in enthalpy (∆H°), Gibbs free energy (∆G°), and entropy (∆S°) indicated that the adsorption is exothermic in nature. The composite has shown promising efficiency for the adsorption of PCT as a model of emergent pollutant from aqueous solutions, making it a viable option for industrial wastewater treatment. Using Density Functional Theory (DFT) along with the 6-31G (d) basis set, the geometric structure of the molecule was determined, and the properties were estimated by analyzing its boundary molecular orbitals. The adsorption energy of PCT on MMT and ca-C.O.R studied using the Monte Carlo (MC) simulation method was −120.3 and −292.5 (kcal·mol⁻¹), respectively, which shows the potential of the two adsorbents for the emerging product. Full article

The main goal of this study is to investigate the possibility of using residual materials (biomass derived from used cooking oils and lignocellulosic biomass from plant waste) on a large scale for producing renewable fuels and, in particular, the best way to collect them. The methodology of Geographic Information Systems (GIS) as well as spatial analysis (SA) techniques were used to investigate the Greek case for this. The data recorded in the geographic database were quantities of waste cooking and household oils as well as quantities of lignocellulosic biomass. The most common global and local indices of spatial autocorrelation were used. Concerning the biomass derived from used cooking oils, it was found that their quantities were important (163.17 million L/year), and these can be used to produce green diesel in the context of the circular economy. Although the dispersion of the used cooking oils was wide, there is no doubt that their concentration in large cities and tourist areas is higher. This finding suggests a collection process that could be carried out mainly in these areas through the development of small autonomous collection units in each neighborhood and central processing plants in small regional units. The investigation of the geographical–spatial distribution of residual lignocellulosic biomass showed the geographical fragmentation and heterogeneity of the distributions. The quantities recorded were significant (4.5 million tons/year) but widely dispersed, such that the cost of collecting and transporting the biomass to central processing plants could be prohibitive. The “geography” of the problem itself suggests solutions of small mobile collection units in every part of the country. The lignocellulosic biomass would be collected and converted in situ into bio-oil by rapid pyrolysis carried out in a tanker vehicle. This would transport the produced bio-oil to the nearest oil refineries for the conversion of bio-oil into biofuels through deoxygenation processes. Full article

Due to their substantial biomass and rapid growth, emergent plants found in wetlands are viewed as excellent sources for biochar production, which has been demonstrated to serve as an effective substitute for absorbite in the effluent treatment. This article systematically contrasted the physicochemical properties of biochar derived from each section of Iris sibirica L. (designated as BC_R, BC_S, and BC_L) under identical pyrolysis conditions, in order to assess their effectiveness in removing cadmium (Cd) from effluent. Experimental results indicated that the removal efficiencies of Cd among the various biochars followed the order BC_S (19.92 mg/g) > BC_L (19.89 mg/g) > BC_R (13.22 mg/g). The removal of Cd²⁺ by biochar is primarily governed by chemisorption, as described by the Langmuir and Freundlich models. Moreover, different adsorption kinetic models, e.g., first-order kinetics, second-order kinetics, intra-particle diffusion, and the Elovich model, were performed to elucidate the adsorption process. Compared to BC_L and BC_R, the proportions of ion exchange and precipitation were more superior in BC_S, reaching 54% and 31%, respectively, which could serve as an effective adsorbent for metal ions, achieving the maximum adsorption capacity. In addition, precipitation (46%) was predominant during the Cd²⁺ adsorption process through BC_R. Therefore, BC_R was more suitable for the acidic wastewater treatment. This study provided an in-depth understanding of the cadmium removal behavior through biochar obtained from different part (roots, stems, and leaves) of wetland plants and introduced a new option for efficient utilization of waste biomass. Full article