Optimum Pyrolysis Temperature Research Articles

Direct flotation separation of active materials from the black mass of lithium nickel cobalt manganese oxides-type spent lithium-ion batteries

Batteries based on lithium nickel cobalt manganese oxides (NCM), which have not been extensively studied, were considered for this study. A black mass (BM) derived from a diverse mix of NCM-type batteries was pyrolyzed at three different temperatures before flotation. The optimum pyrolysis temperature was determined via X-ray spectrometry, contact angle measurements, thermogravimetry, X-ray diffraction, and X-ray photoelectron spectroscopy as 400 °C at which the active materials in the BM were successfully liberated without generating new phases on the material surfaces. This is crucial for recovering materials from the BM using flotation and their potential subsequent application in battery manufacturing, which requires high-purity materials. After optimal pretreatment, the flotation of the treated BM was conducted to separate active materials. At the laboratory scale, the optimal conditions were an impeller speed of 1600 rpm, a collector dosage of 150 g/t, a frother dosage of 150 g/t, and a pulp density of 20 g/L. Furthermore, the initial anode and cathode grades of 84 % and 92 % were further enhanced to 97 % and 95 %, respectively, by employing additional cleaning and scavenging stages. Therefore, this study offers a promising method for recovering high-purity active materials from the BM through systematic pyrolysis pretreatment and subsequent flotation.

Fractionation and Lability of Phosphorus Species in Cottonseed Meal-Derived Biochars as Influenced by Pyrolysis Temperature.

Defatted cottonseed meal (CSM), the residue of cottonseeds after oil extraction, is a major byproduct of the cotton industry. Converting CSM to biochar and utilizing the goods in agricultural and environmental applications may be a value-added, sustainable approach to recycling this byproduct. In this study, raw CSM was transformed into biochar via complete batch slow pyrolysis at 300, 350, 400, 450, 500, 550, and 600 °C. Thermochemical transformation of phosphorus (P) in CSM during pyrolysis was explored. Fractionation, lability, and potential bioavailability of total P (TP) in CSM-derived biochars were evaluated using sequential and batch chemical extraction techniques. The recovery of feed P in biochar was nearly 100% at ≤550 °C and was reduced to <88% at 600 °C. During pyrolysis, the organic P (OP) molecules predominant in CSM were transformed into inorganic P (IP) forms, first to polyphosphates and subsequently to orthophosphates as promoted by a higher pyrolysis temperature. Conversion to biochar greatly reduced the mobility, lability, and bioavailability of TP in CSM. The biochar TP consisted of 9.3-17.9% of readily labile (water-extractable) P, 10.3-24.1% of generally labile (sequentially NaHCO3-extractable) P, 0.5-2.8% of moderately labile (sequentially NaOH-extractable) P, 17.0-53.8% of low labile (sequentially HCl-extractable) P, and 17.8-47.5% of residual (unextractable) P. Mehlich-3 and 1 M HCl were effective batch extraction reagents for estimating the "readily to mid-term" available and the "overall" available P pools of CSM-derived biochars, respectively. The biochar generated at 450 °C exhibited the lowest proportions of readily labile P and residual P compounds, suggesting 450 °C as the optimal pyrolysis temperature to convert CSM to biochar with maximal P bioavailability and minimal runoff risk.

Electrolytic manganese residue-biochar composite for simultaneous removal of antimony and arsenic from water: Adsorption performance and mechanisms

Antimony (Sb) and arsenic (As) pollution in the water environment pose a threat to the ecological environment and human health. A lot of studies have been conducted on the removal of pollutants from water by modified biochar, but little attention has been paid to the simultaneous removal of Sb and As from water. This study aimed to simultaneously remediate the water contaminated by Sb and As and realize the resource utilization of solid waste. Herein, electrolytic manganese residue (EMR)-biochar composite (EB) was prepared by a one-step pyrolysis method using the mixture of EMR and distillers grains for the removal of As(III, V) and Sb(III, V) from water. The results indicated that the optimal pyrolysis temperature and EMR to distillers grains mass ratio for EB removal of As(III, V) and Sb(III, V) were 750 °C and 3∶1, respectively. The removal of As(III, V) and Sb(III, V) by EB was inhibited to varying degrees by HCO3−, PO43−, and humic acid. The maximum adsorption capacities of EB for As(III), As(V), Sb(III), and Sb(V) were 40.92, 40.54, 34.36, and 9.42 mg/g, respectively. The main adsorption mechanisms of As(III, V) and Sb(III, V) included complexation, hydrogen bonding, and pore filling. Compared with other engineered biochar composites, EB can be utilized not only as a potential adsorbent to treat water contaminated with As(III, V) and Sb(III, V), but also to enable the hazard-free treatment and resource utilization of EMR and distillers grains, achieving the goal of treating pollution with waste. Future studies on the remediation performance and mechanisms of EB for practical Sb and As co-contaminated soil and water are necessary.

Green direct ultrasonic slurry sampling and electrothermal atomic absorption spectrometry method for metal analysis of solid plastics samples.

This work presents a "green" analytical method developed for the determination of potentially toxic metals such as aluminium, barium and chromium in solid plastics samples using the slurry sampling technique in conjunction with electrothermal atomic absorption spectrometry. The development of the slurry sampling technique in conjunction with electrothermal atomic absorption spectrometry entailed optimisation of the measuring conditions, which included optimisation of the temperature programme, selection of an appropriate liquid medium for slurry preparation, optimisation of the concentration and volume of the liquid medium and optimisation of the mass of the solid plastics sample. The following conditions were determined: the optimal pyrolysis temperature for aluminium, barium and chromium was in the range of 1300 °C to 1700 °C and the optimal atomisation temperature was in the range of 2100 °C to 2400 °C. The optimal liquid media for solid plastics samples were H2O, 0.2% (v/v) HNO3 and 0.2% (v/v) HCl. The optimal volume of liquid medium was in the range from 5 to 15 mL and the mass of the solid plastics samples was in the range from 30 to 100 mg. The limit of detection and limit of quantification were estimated as 0.06-0.52 ng g-1 and 0.22-1.69 ng g-1 for aluminium, 0.11-0.94 ng g-1 and 0.37-3.14 ng g-1 for barium and 0.07-0.31 ng g-1 and 0.25-1.04 ng g-1 for chromium. Relative standard deviation was below 5% for all plastic samples analysed. Based on the established validation parameters, the slurry sampling technique in conjunction with electrothermal atomic absorption spectrometry represents a viable technique for metal analysis of a variety of plastic materials. The concentrations of analytes in individual solid plastic samples were in the range of 1.36 ± 0.06 μg g-1 to 22.65 ± 0.66 μg g-1 for aluminium, 1.13 ± 0.03 μg g-1 to 6.01 ± 0.22 μg g-1 for barium and 0.60 ± 0.03 μg g-1 to 10.48 ± 0.46 μg g-1 for chromium.

Optimum pyrolysis conditions to prepare the most crystalline boron carbide powder from boric acid-mannitol complex ester.

A weak acidic complex ester (CE) in solid form was prepared by a condensation reaction between very weak boric acid (BA: H3BO3) and (D)-mannitol (MA: C6H14O6) by the molar ratio of BA/MA = 2. A boron carbide (B4C) precursor was obtained from heating of the CE at 400 °C for 4 h. The precursor was pyrolyzed under argon flow in the interval of 1300-1550 °C for 4 h and at 1400 °C for 1-4 h, respectively. The materials were examined using several techniques such as X-ray diffraction analysis, thermal analysis, scanning electron microscopy, particle size distribution, and nitrogen adsorption/desorption. The optimum pyrolysis temperature and duration were 1400 °C and 4 h, respectively. The most crystalline B4C particles were distributed between 1 and 100 μm with a mean particle size of 20 μm. The specific surface area and specific pore volume were 13.5 m2 g-1 and 0.09 cm3 g-1, respectively. The size of the pores was between 2 and 36 nm with a mean size of 14 nm.

Co‐generation and GHG emission from agricultural waste based on pyrolysis/gasification: Experimental and LCA approaches

AbstractIn this study, co‐generation from rice straw based on pyrolysis and gasification was studied by experimental and modeling approaches. Pyrolysis experiment results show that improving pyrolysis temperature will benefit the yield of gas and bio‐oil, while reducing the yield of bio‐char. The BET (Brunauer, Emmett, and Teller) surface area of bio‐char reached a maximum of 143.26 m2/g when the temperature was increased to 550°C. For co‐generation in this study, an optimized pyrolysis temperature of 500°C was selected. With respect to gasification, air equivalence ratio (ER) largely influenced the syngas yield and composition. At ER = 0.25, the concentration of H2 and CO reached a maximum of 17.8 wt% and 16.2 wt%. Based on the experimental results, an Aspen Plus model was built to evaluate the mass and energy balance during co‐generation. Furthermore, a life cycle assessment method was used to evaluate the greenhouse gas emission during co‐generation process initialed from rice straw planting. Results show that the greenhouse gas emission intensities of the two co‐generation systems were 2.92 and 3.51 g CO2/MJ respectively, which were much lower than traditional fossil fuels.

Performance and mechanism analysis of sludge-based biochar loaded with Co and Mn as photothermal catalysts for simultaneous removal of acetone and NO at low temperature.

Replacing NH3 in NH3-SCR with VOCs provides a new idea for the simultaneous removal of VOCs and NOx, but the technology still has urgent problems such as high cost of catalyst preparation and unsatisfactory catalytic effect in the low-temperature region. In this study, biochar obtained from sewage sludge calcined at different temperatures was used as a carrier, and different Co and Mn injection ratios were selected. Then, a series of sludge-based biochar (SBC) catalysts were prepared by a one-step hydrothermal synthesis method for the simultaneous removal of acetone and NO in a low-temperature photothermal co-catalytic system with acetone replacing NH3. The characterization results show that heat is the main driving force of the reaction system, and the abundance of Co and Mn atoms in high valence states, surface-adsorbed oxygen, and oxygen lattice defects in the catalyst are the most important factors affecting the performance of the catalyst. The performance test results showed that the optimal pyrolysis temperature of sludge was 400 °C, the optimal dosing ratio of Co and Mn was 4:1, and the catalyst achieved 42.98% and 52.41% conversion of acetone and NO, respectively, at 240 °C with UV irradiation. Compared with the pure SBC without catalytic effect, the SBC loaded with Co and Mn gained the ability of simultaneous removal of acetone and NO through the combined effect of multiple factors. The key reaction steps for the catalytic conversion of acetone and NO on the catalyst surface were investigated according to the Mars-van Krevelen (MvK) mechanism, and a possible mechanism was proposed. This study provides a new strategy for the resource utilization of sewage sludge and the preparation of photothermal catalysts for the simultaneous removal of acetone and NO at low cost.

Pyrolysis recovery and product distribution of shrimp shell waste: Insights from thermogravimetric-Fourier transform infrared spectroscopy and pyrolysis–gas chromatography/mass spectrometry characterization

Shrimp consumption is increasing owing to its rich nutrition and delicious taste. As a result, the generation of shrimp shell waste is also increasing, while the current disposal method such as landfilling causes pollution and produces harmful leachate to living organisms and the environment. Therefore, a proper management strategy is needed to dispose of shrimp shell waste to mitigate the adverse effects caused to the environment. This study presents an in-depth approach to reveal the properties of shrimp shell waste and explore its potential for use in various applications. The shrimp shell waste was subjected to pyrolysis–gas chromatography/mass spectrometry and thermogravimetric-Fourier transform infrared spectroscopy pyrolysis to evaluate the gas composition from pyrolysis. Thermogravimetric-Fourier transform infrared spectroscopy analysis reveals that when the optimal temperature for pyrolysis is 400 °C–600 °C, the predominant functional group of gases produced are –CH, –OH, and –NH. On the other hand, the results of pyrolysis–gas chromatography/mass spectrometry indicate that hydrocarbon (51.86%) is the main product of shrimp shell waste pyrolysis at 900 °C, which can be used in paints, paint thinners, rubber, printing inks, adhesives (glue). Although it has a calorific value of 15.113 MJ/kg, it cannot be directly burned because of its high nitrogen concentration (10.85 wt.%) which may generate harmful pollutants such as nitrogen oxides. Overall, pyrolysis is recommended as a viable method for converting shrimp shell waste into versatile products.

ZIF-8-derived magnetic FCZ@C-600 composite for efficient adsorptive removal of unsymmetrical dimethylhydrazine from wastewater

Efficient and convenient removal of hazardous unsymmetrical dimethylhydrazine (UDMH) remains challenging for ecological security and human health. In this work, ZIF-8-derived magnetic porous carbons (FCZ@Cs) were synthesized via layer-by-layer self-assembly and pyrolysis using chitosan as an external carbon source. The optimal pyrolysis temperature of FCZ@Cs is 600 °C and the maximum adsorption capacity of FCZ@C-600 for UDMH is 185.70 mg/g at 298 K. Moreover, FCZ@C-600 has wide pH adaptability and good resistance to acid, natural organic matter, and interfering ions. UDMH adsorption onto FCZ@C-600 and ZIF-8-600 conforms to pseudo-second-order and Langmuir models. Thermodynamic studies demonstrate that the adsorption performance is endothermic and favorable. Mechanisms investigations further identify electrostatic interactions, diffusion, and hydrogen/coordination bonds as the greatest contributors to UDMH adsorption. Notably, magnetic FCZ@C-600 can be readily separated by a magnet and exhibits high stability with an adsorption capacity of 42.05 mg/g after six cycles. Furthermore, the leaching concentration of Fe and Zn can be as low as 0.3 mg/L and 1.0 mg/L (pH ≥ 4), respectively. UDMH wastewater after adsorption also shows good biosafety. This work provides insights into the development of emerging metal-organic framework-derived adsorbents with multifunctionality and good sustainability for efficient wastewater treatment.

In situ activation synthesis of tire-derived sorbents for efficient immobilization of elemental mercury from flue gas

Mercury removal from coal combustion flue gas remains a daunting challenge because of the lack of cost-effective sorbents. In this study, the in situ activation synthesis of tire chars was realized through SO2 induction and the tire-derived sorbents were used for elemental mercury (Hg0) removal from the simulated flue gas. Therein the sulfur species in tire chars are regulated. The results indicated that the specific surface area of tire chars was slightly decreased whereas more micropores were generated after SO2 activation. Compared with raw tire char, the sulfur content of tire-derived sorbents was obviously increased. The tire-derived sorbents also contained more sulfur- and oxygen-containing functional groups. For this reason, the Hg0 removal performance of tire-derived sorbents was dramatically increased after SO2 activation. The optimum pyrolysis temperature for the synthesis of tire-derived sorbents was 600 °C. The SO2 concentration in activation atmosphere had little effect on the Hg0 removal performance of tire-derived sorbents. The presence of SO2, NO and O2 was beneficial for Hg0 removal·H2O had little effect on Hg0 removal. The Hg0 adsorption capacity of tire-derived sorbents was further compared with the previously reported sorbents through adsorption dynamic simulations. Furthermore, the mechanism of Hg0 removal over tire-derived sorbents was revealed through XPS analysis and mercury temperature programmed desorption. It was found that the Hg0 removal process was mainly dominated by chemisorption, where organic sulfur species, CO group and COOH/C(O)–O–C group served as active sites for Hg0 capture.

Activated Carbon and P-Rich Fertilizer Production from Industrial Sludge by Application of an Integrated Thermo-Chemical Treatment

The cost and environmental impact of sludge disposal methods highlight the necessity of new solutions for resource recovery. This study aims at concurrently producing activated carbon while recovering phosphorous by applying an integrated thermo-chemical treatment to a sludge of industrial origin. The sludge was first subjected to slow pyrolysis on a laboratory scale at different temperatures, and the produced chars were processed by leaching to obtain biocoal. Leaching tests enabled us to define the optimal slow pyrolysis temperatures to maximize leaching performances. Then, sludge was processed in a slow pyrolysis pilot-scale plant, and the produced char was subjected to acid leaching and finally to physical activation. Chemical precipitation was then applied to the liquid leachate to recover phosphorous as a salt. Laboratory-scale slow pyrolysis and leaching tests showed that a higher pyrolysis temperature leads to a lower degree of demineralization by leaching. Leaching enabled us to reduce the char ash content by almost 88%, extracting 100% P, Mg, Ca, and Fe and almost 90% Al. Physical activation of biocoal with CO2 at 700 and 800 °C produced materials with a surface area of 353 and 417 m2 g−1, respectively, that make them potentially applicable as adsorbents in wastewater treatment or in industrial emissions processes. Moreover, the activated carbons showed the atomic H/C and O/C ratios of anthracite, which opens a wide range of alternative market applications to fossil coal, such as metallurgy and the advanced material sector. In addition, the high P and K concentrations in the salt obtained by precipitation make it a promising fertilizing product in line with the current regulations.

Induced synthesis of SO2-promoting and H2O-tolerant sorbents for elemental mercury removal from flue gas

In this study, novel S-doped sorbents synthesized via one-step co-pyrolysis of biomass and scrap tires under SO2 atmosphere were developed for elemental mercury (Hg0) removal from coal-fired flue gas. The presence of SO2 could regulate the sulfur species in S-doped sorbents and improve their Hg0 removal performance. Sample characterization exhibited that SO2 activation increased the sulfur content and decreased the carbon content in sorbents due to the occurrence of carbothermal reduction reaction. The specific surface area, pore volume, and micropore content in S-doped sorbents were obviously improved compared with raw sorbents. After SO2 activation, partial inorganic sulfide was converted into sulfur-containing functional groups and more oxygen-containing functional groups were generated on the sorbents. The S-doped sorbents presented more excellent performance for Hg0 removal compared with raw sorbents. The optimal pyrolysis temperature and SO2 concentration in activation atmosphere were 700 °C and 10%, respectively. It was surprising that SO2 facilitated Hg0 removal and the S-doped sorbents showed good water-resistance due to the presence of ZnS. O2 and NO had positive effects on Hg0 removal. A close fitting to the pseudo-second-order model was obtained for the behavior of Hg0 removal over S-doped sorbents. Aliphatic sulfur, sulfoxide, carbonyl and carboxyl/ester groups functioned as active components for Hg0 removal.

Study on the kinetic-guided pyrolysis of oil shale kerogen catalyzed by needle-like NiFe-LDH

An in-depth understanding of the thermo-physicochemical behavior of kerogen catalytic pyrolysis is helpful to realize the efficient utilization of oil shale. In this work, the pyrolysis behavior of Barkol Kerogen and its product distribution were investigated by dry distilled experiment with needle-like NiFe-LDH as Catalyst, which was designed based on the kinetic experiments. As a result, NiFe-LDH has low-temperature and high-efficiency pyrolysis catalytic activity in the oil shale recovery and product selectivity. The initial pyrolysis catalytic temperature of kerogen was advanced to 250 °C, and the optimum pyrolysis temperature was decreased by 42.02 °C. The catalytic pyrolysis temperature was selected as 400 °C because of the maximum temperature weight loss in thermal analysis. NiFe-LDH not only increased the oil yield of kerogen by 5.18% and alkane selectivity by 2.62% but also reduced the content of heteroatomic hydrocarbon by 6.46%. Simultaneously, according to the change of activation energy during thermal analysis and the results of pyrolysis experiment, the catalytic pyrolysis process was speculatively divided into three possible stages. This resolution is helpful to understand the catalytic effect of NiFe-LDH on kerogen. Thus, NiFe-LDH plays a distinct role in the catalytic pyrolysis of kerogen and its kinetic regulation.

Investigation on chemically modified carbon black in enhancing asphalt performance

Asphalt is still regarded as the most common raw material for road paving. In the pursuit of more long-term sustainability and the creation of durable and resilient pavements, researchers are diligently exploring high-quality asphalt. The objective of this study was to delve into the behavior of carbon black (CB)-modified asphalt, through conducting the conventional tests. The determination of the optimal pyrolysis temperature for CB involved assessing productivity, ash content, oil absorption value, iodine absorption value, and scanning electron microscopy (SEM). The modification was undertaken to generate modified carbon black (MCB), involving nitric acid oxidation and hydroxymethylation. The MCB was confirmed through total acidity (T), carboxyl and lactone groups (P), and hydroxyl groups (Q), complemented by SEM, Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) characterization. The optimal MCB dosage determination of 15 % was accomplished by employing three index tests. Fluorescence microscopy was employed to illustrate the dispersion compatibility between MCB and asphalt. To assess the high-temperature performance and resistance to aging of CB and MCB modified asphalt, dynamic shear rheometer (DSR) temperature scanning was employed. The findings revealed that MCB significantly enhanced the temperature sensitivity, viscosity, rheological properties, and high-temperature characteristics of the modified asphalt. Moreover, the incorporation of CB and MCB exhibited improved anti-aging behavior in the asphalt.

Pyrolysis behaviour of shellfish waste via TG-FTIR and Py-GC/MS

Shellfish waste (SW), a by-product of seafood processing and consumption, poses ecological concerns from improper management, resulting adverse effects such as water pollution, habitat degradation, and destruction of local ecosystems. Furthermore, the inefficient disposal of SW goes against the principles of circular economy and resource utilization. Therefore, this study is conducted to convert and reuse SW and transform it into value-added products, thereby contributing to sustainable waste management practices. Shellfish waste was characterized for its elemental and proximate contents, followed by performing pyrolysis of SW to study the pyrolysis behaviors and chemical composition of pyrolytic products. Thermogravimetric analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR) was employed to identify the optimal pyrolysis temperature range (660–780 °C). Additionally, pyrolysis combined with gas chromatography/mass spectrometry (Py-GC/MS) was utilized to analyze gaseous products generated from SW pyrolysis. The analysis revealed that SW possesses a low high calorific value (5.57–8.05 MJ/kg) and high H/C (0.3–1.3) and O/C (3.2–5.2) ratios, rendering it unsuitable for direct use as fuel. Optimal pyrolysis conditions were identified within the temperature range of 660–780 °C through TG-FTIR analysis. Py-GC/MS analysis at 700 °C and a heating rate of 30 °C/min indicated that carboxyl compounds (37.3–87.0%) constituted the dominant components of gaseous products generated during SW pyrolysis. In conclusion, the study underscores the promise of pyrolysis as a viable method for transforming SW into value-added chemicals. The findings of this study contribute to the advancement of sustainable waste management strategies and the utilization of waste materials for valuable purposes in various industries.

Influence of Pyrolytic Carbon Black Derived from Waste Tires at Varied Temperatures within an Industrial Continuous Rotating Moving Bed System.

Nowadays, waste tires have emerged as one of the most significant sources of environmental pollution. To address this issue, pyrolysis has become a widely adopted method. The continuous rotary kiln reactor has particularly gained popularity in industrial production for pyrolysis due to its suitability. In order to guide the development of new industrial continuous rotary kiln reactors and achieve high-performance pyrolytic carbon black (CBp), this study was conducted to investigate the relationship between the physical and chemical characteristics of CBp and pyrolysis temperature. The elevated-temperature procedure led to a reduction in DBP values from 90 to 70 mL/100 mg, accompanied by a rise in the specific surface area from 63 to 77 m2/g. The augmentation of pyrolysis temperature was noted to induce the agglomeration of CBp particles, thereby negatively impacting their dispersion within polymer matrices. CBp particles at 550 °C exhibited greater structural order, as determined by Raman spectroscopy, which can be attributed to the elevated temperature proximate to the cylinder wall surface. Furthermore, the potential of CBp for reinforcement in natural rubber (NR) was taken into consideration. The pronounced propensity of high-temperature CBps to agglomerate led to uneven dispersion within the polymer, consequently causing heightened heat accumulation and the emergence of the Payne effect. Based on a thorough analysis of the outcomes, the optimal pyrolysis temperature for CBp synthesis within the continuous reactor was ascertained.

Pyrolysis of cellulose in Fe‐[Bmim]OTf catalyst for selective production of 4,4‐dimethyl‐2‐cyclohexen‐1‐one

Abstract4,4‐dimethyl‐2‐cyclohexene‐1‐one is a valuable ketone compound, which is an important (±)‐cuparene and filicinic acid intermediate, but the synthetic method of 4,4‐dimethyl‐2‐cyclohexene‐1‐one is rarely mentioned in the marketplace. This article, a new method is proposed for the preparation of 4,4‐dimethyl‐2‐cyclohexen‐1‐one in high yield by selective catalytic pyrolysis of cellulose with FeCl3‐doped [Bmim]OTf magnetic ionic liquids. By studying the effect of temperature on the yield of pyrolysis products in [Bmim]OTf, the results showed that the optimal pyrolysis temperature of cellulose in [Bmim]OTf was 330°C and the maximum relative content of 4,4‐dimethyl‐2‐cyclohexen‐1‐one was 86.81%. In addition, different FeCl3/[Bmim]OTf mass ratios were found at 330°C. The relative yield of the target product reached a maximum (91.31%) when iron ions with excellent catalytic activity were introduced, at which the FeCl3/[Bmim]OTf mass ratio was 10%. At last, based on the basic model of cellulose monomer, the evolution pathway of ketones products was proposed, which provides ideas for the production of sustainable chemical products from cellulose.

Effect of the catalyst type on pyrolysis products distribution of polymer blends simulating plastics contained in waste electric and electronic equipment

The valorization of the plastic part from waste electric and electronic equipment (WEEE) is of significant importance for the upcycling of this waste stream with pyrolysis proposed as an appropriate, environmentally friendly, thermo-chemical recycling technique. The subject of this study is to investigate the distribution of the products obtained after the addition of certain catalysts in the pyrolysis of polymer blends with a composition similar to that of plastics in WEEE. Specifically, blends of acrylonitrile-butadiene-styrene (ABS), high impact polystyrene (HIPS), polycarbonate (PC), polypropylene (PP) and poly(vinyl chloride) (PVC) were examined in experiments taking place in a lab scale pyrolyser coupled with gas chromatography/mass spectrometry (Py-GC/MS) for the on-line recording of the products obtained. Six different catalysts (CaO, γ-Al2O3, Fe2O3, ZSM-5, Silicalite, Al-MCM41) were used and the optimum pyrolysis temperatures were selected for each system based on evolved gas analysis. The results from catalytic cracking were compared and evaluated in terms of the number of compounds produced, the ratio between aromatic and aliphatic products, and the intensity of the peaks. It was found that the best choice for the decomposition of ABS is Fe2O3 and for HIPS the Al-MCM41. γ-Al2O3 affects PC degradation and CaO exhibits specific selectivity to this polymer. Pyrolysis of blends results in the production of a mixture of hydrocarbons together with other aliphatic and aromatic compounds. Polymer blends including chlorinated compounds such as PVC start degrading at relatively low temperatures, slightly over 200 °C. Degradation occurs in two steps with peaks around 300 and 465 °C, respectively. The first is attributed to the removal of halogenated compounds and the second to the scission of the main carbon chain. PVC degradation produces chlorine radicals that affect the degradation mechanism. The presence of the catalysts did not significantly change the temperatures of degradation. However, they do change the type of the products obtained. Pyrolysis of the styrenic polymers, i.e. ABS or HIPS resulted in mainly aromatic compounds with one, two or even three aromatic rings, whereas PC results in several phenols. CaO is proposed as the best choice for catalytic cracking of Blend A, whereas Silicalite should be considered for Blend B since it leads in the production of more aromatic compounds compared to conventional pyrolysis.

Characterization of carbon quantum dots obtained through citric acid pyrolysis

Carbon quantum dots (CQDs) were produced through citric acid (CA) pyrolysis. For the first time, we searched for the optimum CA pyrolysis duration and temperature. As a basic quality criterion of quantum dots, photoluminescence quantum yield (QY) was chosen. For this purpose, the pyrolysis products were analysed with UV–Vis spectroscopy and fluorescence (FL) spectroscopy. The optimum pyrolysis time was accepted to be 240 min, whereas the optimum pyrolysis temperature was approved as 200 °C. The pyrolysis products obtained at the optimum conditions were further subjected to dialysis. Finally, the purified CQDs were characterised with FL spectroscopy, transmission electron microscopy, dynamic light scattering, Raman spectroscopy, and Fourier transform infra-red spectroscopy. The produced CQDs were shown to be stable in water solution. Their PL QY (6.1%) was decreased to 1.2% after CQDs exposure to daylight for 90 days. Luminescent polymer composites were produced when CQDs were embedded in the poly(vinyl alcohol) and bacterial cellulose matrices. The prepared composites can be used for fabrication of transparent, flexible, and luminescent films and for production of anti-counterfeiting paper for confidential documents, labels, and banknotes.

Study on Adsorption of Phosphate in Water Environment by Mg–Al Modified Biochar

Excessive release of phosphate has gained prominence as a pivotal contributor to water contamination. Biochar, known for its abundant surface acreage and unparalleled adsorptive prowess, has been widely employed in aqueous remediation. Within the scope of this investigation, unprocessed biochar was derived from Chaetomorpha valida via pyrolysis methodologies involving temperatures ranging from 320 °C, 460 °C, 620 °C, and 860 °C, respectively. Mg-BC620, Al-BC620, and Mg–Al-BC620 were prepared using the co-precipitation method at the optimal temperature to maximize the resource utilization of Chaetomorpha valida. The physicochemical attributes of altered biochars were evaluated employing X-ray diffractometry and other analytical techniques. The influence of different factors on phosphate’s adsorptive aptitude of altered biochar was investigated, and the adsorptive behavior and mechanism of biochar were studied using diverse kinetics of adsorption and assortment of isotherm models. The outcomes revealed that the optimal pyrolysis temperature was 620 °C, and the altered biochar displayed a strikingly elevated affinity for phosphate sorption, outperforming the unaltered biochar. Among the modified biochars, Mg–Al-BC620 outperformed the rest, boasting an astonishing eradication rate of 94.92% when dosed at 8 g/L, maintaining a pH equilibrium of 7 in the solution, while confronting an inceptive phosphate density of 150 mg/L. The utmost threshold of adsorption proficiency predicted by the Langmuir equation was 228.130 mg/g, which was 88.56 times that of BC620. This modified biochar exhibits a strong affinity for phosphate and excellent adsorption selectivity, providing a promising avenue for the resource utilization of Chaetomorpha valida and has broad application prospects for scavenging phosphate in aqueous mediums.