Carbonaceous Materials Research Articles

Flash‐sintering behavior of the composites of 3YSZ and graphene oxide

AbstractFlash sintering is a novel technique that involves the sintering of green bodies in few seconds at relatively very low furnace temperature as compared to what is required to sinter them conventionally. In the present work, we flash‐sintered composites of 3 mol.% yttria‐stabilized zirconia (3YSZ) and graphene oxide (GO). The main aim of this work was to see if the decomposition or oxidation of carbonaceous materials can be prevented by the high heating rates during flash sintering and if composites of 3YSZ and GO can be processed in air. 3YSZ with 5, 10, and 20 wt.% of GO were prepared and subjected to constant heating rate flash‐sintering experiments where electric field was applied across the sample right from room temperature. A DC electric field of 100 V/cm was applied and the current density was set to 100 mA/mm2. It was observed that GO decomposed from the surface of the samples; however, in the core of samples, GO was retained but was reduced to graphite. Grain size of the 3YSZ phase increased with increase in the GO content, whereas the hardness decreased. It was observed that the composites containing carbonaceous reinforcements need to be flash sintered in inert atmosphere to realize their full potential.

Ionothermal Carbonization of Sugarcane Bagasse in 1-Alkyl-3-methylimidazolium Ionic Liquids: Insights into the Role of the Chloroferrate Anion.

We report the ionothermal carbonization (ITC) of lignocellulosic biomass in imidazolium tetrachloroferrate ionic liquids (ILs) as an advantageous approach for the preparation of nanostructured carbonaceous materials, namely, ionochars. In a previous study, we investigated the role of the imidazolium cation and demonstrated the possibility of controlling both the textural and morphological properties of ionochars by cation engineering. Although essential for providing intermediate Lewis acidity and relatively high thermal stability, the role of the chloroferrate anion is still open to debate. Herein, we investigated the ITC of sugarcane bagasse and its main component, cellulose, in 1-alkyl-3-methylimidazolium ILs with different chloroferrate anions. We identified anionic speciation and its impact on the properties of the IL by Raman spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The obtained ionochars were characterized by gas physisorption, electron microscopy, Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and 13C solid-state CP-MAS NMR spectroscopy. We show that the anionic species have a predominant impact on the textural and morphological properties of the ionochars.

Opinions on the Development of Ultrahigh Permeation Membranes

In this work, recent progresses made in the development of membranes with ultrahigh permeation rate for reverse osmosis (RO) and membrane distillation (MD) are briefly summarized and the future prospect of those membranes is discussed. In fabrication of ultrahigh permeation RO membranes, carbon nanotube, aquaporin, graphene and fluorous oligoamide nanorings were used and in all of them several orders of magnitude higher fluxes than the conventional commercial membranes were achieved. Ultrahigh MD membranes were fabricated mostly from carbonaceous materials also with several orders of magnitude higher fluxes than conventional commercial membranes, except for those made of ultrathin polymeric material, which demonstrated a high flux at a low transmembrane temperature difference. Despite these remarkable achievements, it was concluded that many challenges would be encountered to produce a sufficient amount of water by the so-called membrane chips.

Enhancing Uptake Capability of Green Carbon Black Recycled from Scrap Tires for Water Purification

This study reports on the highly simple fabrication of green carbon black (GCB) generated from scrap tires with acetic acid to improve the adsorption efficiency for water purification, which is thoroughly compared with conventional carbon black (CB) obtained from petrochemicals. Unlike traditional modification processes with strong acids or bases, the introduction of a relatively mild acid readily allowed for the effective modification of GCB to increase the uptake capability of metal ions and toxic organic dyes to serve as effective adsorbents. The morphological features and thermal decomposition patterns were examined by electron microscopy and thermogravimetric analysis (TGA). The surface functional groups were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The structural information (ratio of D-defects/G band-graphitic domains) obtained by Raman spectroscopy clearly suggested the successful fabrication of GCB (ID/IG ratio of 0.74), which was distinctively different from typical CB (ID/IG ratio of 0.91). In the modified GCB, the specific surface area (SBET) gradually increased with the reduction of pore size as a function of acetic acid content (52.97 m2/g for CB, 86.64 m2/g for GCB, 102.10-119.50 m2/g for acid-treated GCB). The uptake capability of the modified GCB (312.5 mg/g) for metal ions and organic dyes was greater than that of the unmodified GCB (161.3 mg/g) and typical CB (181.8 mg/g), presumably due to the presence of adsorbed acid. Upon testing them as adsorbents in an aqueous solution, all these carbon materials followed the Langmuir isotherm over the Freundlich model. In addition, the removal rates of cationic species (>70% removal of Cu2+ and crystal violet in 30 min) were much faster and far greater than those of anionic metanil yellow (<40% removal in 3 h), given the strong electrostatic interactions. Thus, this work demonstrates the possibility of recycling waste tires in the powder form of GCB as a cost-effective and green adsorbent that can potentially substitute traditional CB, and the modification strategy provides a proof of concept for developing simple fabrication guidelines of other carbonaceous materials.

Specific Removal and Recovery of Bromide Ions: The Search for Stable Electrodes and Operation Modes

In previous work, we introduced an elegant approach for bromide recovery from water by the introduction of a hybrid physical adsorption and capacitive deionization processes for selective removal and recovery of boron from water. In this paper, we show that the harsh environment of water contaminated with bromine-moieties adversely affects the longevity of relevant electrodes, with close to 100 consecutive work hours of bromides removal without noticeable degradation. To extend the lifespan of electrodes, we used an asymmetric CDI cell with a 1:5 positive/negative electrodes ratio in which a polarity switch between electrodes is applied every six adsorption-desorption cycles in a way that in each adsorption-desorption cycle, a different electrode of the six electrodes, functions as the positive electrode. We deduce that the polarity switch reduces oxidation and subsequent degradation of the positive electrodes, resulting in an extended lifecycle. After examining nine different carbonaceous materials, carbon cloth was chosen to be incorporated in the bromide- recovery cells because of its favorable kinetics and its physical and mechanical properties. We show that with a combination between endurance of the electrodes and asymmetric mode of operation, it is possible to overcome the main barrier that holds the technology from being practical.

Research progress on lignin-based carbon electrode materials in rechargeable batteries

Lignin, with its carbon content of up to 60%, can be an ideal precursor for the preparation of carbon materials. Carbonaceous materials obtained from lignin can be transformed into porous and structural morphologies at different scales, providing a biomass approach to energy conversion and storage in batteries. Focusing on lignin-derived carbon materials, this paper summarizes the different morphologies and structures of lignin-based carbon obtained through different preparation methods, and the different electrochemical properties exhibited by these materials as electrode materials for rechargeable batteries (lithium-ion batteries, sodium-ion batteries, lithium-sulphur batteries, etc.). In addition, the development prospects and challenges of lignin-based carbon materials in the field of rechargeable batteries are summarized, providing ideas for the next step in the design and development of high-performance lignin-based carbon-based electrode materials.

Promoting the circular economy: Valorization of a residue from industrial char to activated carbon with potential environmental applications as adsorbents

Pyrolysis of residues enriched with carbon, such as in agroforestry or industrial activities, has been postulated as an emerging technology to promote the production of biofuels, contributing to the circular economy and minimizing waste. However, during the pyrolysis processes a solid fraction residue is generated. This work aims to study the viability of these chars to develop porous carbonaceous materials that can be used for environmental applications. Diverse chars discharged by an industrial pyrolysis factory have been activated with KOH. Concretely, the char residues came from the pyrolysis of olive stone, pine, and acacia splinters, spent residues fuel, and cellulose artificial casings. The changes in the textural, structural, and composition characteristics after the activation process were studied by N2 adsorption-desorption isotherms, scanning electron microscopy, FTIR, elemental analysis, and XPS. A great porosity was developed, SBET within 776–1186 m2 g−1 and pore volume of 0.37–0.59 cm3 g−1 with 70–90% of micropores contribution. The activated chars were used for the adsorption of CO2, leading to CO2 maximum uptakes of 90–130 mg g−1. There was a good correlation between the CO2 uptake with microporosity and oxygenated surface groups of the activated chars. Moreover, their ability to adsorption of contaminants in aqueous solution was also evaluated. Concretely, there was studied the adsorption of aqueous heavy metals, i.e., Cd, Cu, Ni, Pb, and Zn, and organic pollutants of emerging concern such as caffeine, diclofenac, and acetaminophen.

Sonocatalytic Activity of Porous Carbonaceous Materials for the Selective Oxidation of 4-Hydroxy-3,5-dimethoxybenzyl Alcohol.

Selective oxidation, which is crucial in diverse chemical industries, transforms harmful chemicals into valuable compounds. Heterogeneous sonocatalysis, an emerging sustainable approach, urges in-depth exploration. In this work, we investigated N-doped or non-doped carbonaceous materials as alternatives to scarce, economically sensitive metal-based catalysts. Having synthesized diverse carbons using a hard-template technique, we subjected them to sonication at frequencies of 22, 100, 500, and 800 kHz with a 50% amplitude. Sonochemical reaction catalytic tests considerably increased the catalytic activity of C-meso (non-doped mesoporous carbon material). The scavenger test showed a radical formation when this catalyst was used. N-doped carbons did not show adequate and consistent sonoactivity for the selective oxidation of 4-Hydroxy-3,5 dimethoxybenzyl alcohol in comparison with control conditions without sonication, which might be associated with an acid-base interaction between the catalysts and the substrate and sonoactivity prohibition by piridinic nitrogen in N-doped catalysts.

The surface asymmetric site regulation of carbon nitride oxide enabling peroxymonosulfate activation for degrading tetracycline

Peroxymonosulfate (PMS) activation by the carbonaceous-based materials for degrading antibiotics is a recent emerging hotspot in water environment restoration. Herein, a triazine carbon material is prepared by urea thermal condensation follwed by water-mediated oxidation. The optimized triazine carbon material (CNOR15) can degrade around 100 % of tetracycline within 6 mins, thus pseudo-first-order kinetic constant (kobs) enhances approximately 49 folds compared to pristine carbon material. Experiments and characterizations demonstrate non-radical reactive species of 1O2 plays a crucial role in CNOR15/PMS system to eliminate tetracycline, in which performs at an asymmetric C = O site on the edge of triazine motief. Electron paramagnetic resonance and trapping tests comfirm the novel mechanism of electron conduction from sp/sp2-hybrdized triazine to C = O prompting PMS decomposition for 1O2 generation. Ex-situ argon sputtering XPS technology solidly unveils a underlysing linear corelation between catalysis activity and content of carbonyl-constructed assymetric sites. In addition, membranoid CNOR15/PVDF removes ca. 90 % tetracycline at a rate of 100 mL·min−1 in a continuous flow-cell device, exhibiting a promising application in the practical wastewater purification. Our work emphasized a significance of asymmetric site regulation of carbonaceous materials towards PMS activation for environmental remediation.

Utilizing Carbonaceous Materials Derived from [BMIM][TCM] Ionic Liquid Precursor: Dual Role as Catalysts for Oxygen Reduction Reaction and Adsorbents for Aromatics and CO2.

This work presents the synthesis of N-doped nanoporous carbon materials using the Ionic Liquid (IL) 1-butyl-3-methylimidazolium tricyanomethanide [BMIM][TCM] as a fluidic carbon precursor, employing two carbonization pathways: templated precursor and pyrolysis/activation. Operando monitoring of mass loss during pyrolytic and activation treatments provides insights into chemical processes, including IL decomposition, polycondensation reactions and pore formation. Comparatively low mass reduction rates were observed at all stages. Heat treatments indicated stable pore size and increasing volume/surface area over time. The resulting N-doped carbon structures were evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and adsorbents for gases and organic vapors. Materials from the templated precursor pathway exhibited high electrocatalytic performance in ORR, analyzed using Rotating Ring-Disk electrode (RRDE). Enhanced adsorption of m-xylene was attributed to wide micropores, while satisfactory CO2 adsorption efficiency was linked to specific morphological features and a relatively high content of N-sites within the C-networks. This research contributes valuable insights into the synthesis and applications of N-doped nanoporous carbon materials, highlighting their potential in electrocatalysis and adsorption processes.

Thermocatalytic decomposition of methane to low-carbon hydrogen using LaNi1-xCuxO3 perovskite catalysts

The thermocatalytic decomposition (TCD) of methane is an attractive alternative to produce low-carbon hydrogen and solid carbonaceous materials. In this study, substituted LaNi1-xCuxO3 perovskite catalysts prepared via self-combustion method were investigated for methane TCD. The effect of Ni partial substitution with Cu, varying gas hourly space velocity, temperature and stability on methane conversions were evaluated. PXRD, H2-TPR, SEM-EDS, TGA, and XPS were used to characterize the catalysts. An increase in Cu loading to 50%, increase in temperature and decrease in GHSV resulted in an improvement in methane conversions to 92%. At a GHSV of 2400 ml/gcat.h, no significant deactivation was observed as the stability of the LaNi0.5Cu0.5O3 catalyst increased from 6 to 20 hours’ TOS with methane conversions maintained at 92% where carbon nanofibers were observed on the surface of the spent catalysts. The study demonstrates the potential to prepare LaNi1-xCuxO3 catalysts and identify optimal testing conditions for the novel production of low-carbon hydrogen with minimal catalyst deactivation.

Unravelling the influence of surface functional groups and surface charge on heavy metal adsorption onto carbonaceous materials: An in-depth DFT study

Theoretical analyses were explored for the adsorption of heavy metals in aqueous systems, focusing on the influence of surface charge and functional groups of carbonaceous materials. The approach involved the meticulous assignment and interpretation of active adsorption bands, achieved through modelling of Fourier Transform Infrared (FT-IR) and X-ray Photoelectron Spectroscopy (XPS) spectra. Additionally, atomic charges were analyzed, utilizing their chemical properties to glean valuable insights into the atomic-level intricacies of the adsorption process. The structural parameters of the carbonaceous surface reveal that in unsaturated models, heavy metals preferentially adsorb onto neighboring carbons due to facilitated electron transfer. Conversely, adsorption predominantly occurs in saturated models within functional groups, except for interactions involving the phenolic group, where it occurs on the carbonaceous matrix. Overall, negative ΔG values were observed across a range of temperatures from 285 to 315 K, as evidenced by Gibbs free energy values ranging from −72.93 kcal/mol (Ni2+ on carboxylate) to −4.98 kcal/mol (Cd2+ on ketone), confirming the spontaneous and thermodynamic feasibility nature of the adsorption processes for heavy metals on biochar across all evaluated functional groups, following the trend Ni2+ > Zn2+ > Co2+ > Cd2+. These trends can be rationalized in terms of: a) the size-dependence, where smaller cations such as Ni2+ (0.69 Å) form more stable adsorption complexes than Cd2+ (0.95 Å); b) charge transfer, higher adsorption energy (-55.60 kcal/mol) corresponds to a greater magnitude of charge transfer (0.32e); and c) the electronegativity of the respective metals, which are as follows: 1.367 for Ni2+, 1.349 for Co2+ and 1.336 for Zn2+. Consequently, Ni2+ exhibits a greater propensity to accept electrons from oxygen biochar than Co2+ and Zn2+ atoms. Finally, the assignment of IR and XPS is challenging in the laboratory, facing several endeavours. Our findings indicate a notable shift in the C―O stretching signal from 1631 cm−1 (in the clean system) to 1652 cm−1 upon Cd2+ adsorption, with Co2+, Ni2+, and Zn2+ showing shifts to 1690 cm−1 and 1685 cm−1 for the latter two cases, respectively. Therefore, the theoretical signals reported in the current work are a helpful tool as benchmark data to address and complement further experimental information. Indeed, the modelling of IR and XPS fit with some experimental values for some representative cases, implying appropriate modelling of the above systems.

Exploring the peroxydisulfate activation by carbon nanotubes for pollutants degradation: Identification of the primary reaction mechanism and key molecular descriptor

Carbon nanotubes (CNT) have been proposed to activate persulfate over the past decade, resulting in successful degradation performance for organic pollutants in wastewater treatment. However, there is debate over the reaction mechanism involving radical versus non-radical pathways, setting up a roadblock to further developing persulfate activation by carbonaceous materials. This work focused on the carbon nanotubes/peroxydisulfate (CNT/PDS) system, investigated its reaction mechanism, and unveiled the relationship from the aspect of molecular descriptors. The involvement of radicals (e.g., SO4•− and HO•) and 1O2 was ruled out by the observation of quenching effect, oxidation products, chemical probes, solvent exchange, and electron paramagnetic resonance spectra. Then, mediated electron transfer was deemed as the primary reaction mechanism based on linear sweep voltammetry analysis, which was supported by the PDS consumption result. The substrate-dependent treatment capacity was found in the CNT/PDS for multiple contaminants degradation, and it turned out that EB3LYP was the most significant parameter in the relationship between degradation rates and molecular descriptors. Outstanding environmental application was exhibited based on the coexistence of various organic/inorganic substances and repeated degradation experiment. Therefore, the findings from this study would be helpful for both scientific research and technical development of persulfate activation by CNT.

The correlation between electron exchange capacity of Fenton-like heterogeneous catalyst and catalytic activity

Electron transfer played key role in peroxymonosulfate (PMS) activation for heterogeneous Fenton-like catalysts (HFCs). However, the relationship between electron exchange capacity (EEC) and catalytic activity of HFCs has not been elucidated. Herein, thirteen HFCs reported in our previous studies were selected to measure their EEC via electrochemical methods and to investigate the correlation between EEC and catalytic activity for PMS. The results show that nitrogen-doped graphene oxide had much higher EEC (5.299 mM(e) g−1), followed by reduced graphene oxide (3.23 mM(e) g−1), nitrogen-doped biochar-700 (2.032 mM(e) g−1), graphene oxdie (1.789 mM(e) g−1), nitrogen-doped biochar-300 (1.15 mM(e) g−1), g-C3N4 (0.752 mM(e) g−1) and biochar (0.351 mM(e) g−1). For carbon materials, their catalytic activity was not determined by electron donor capacity (EDC), electron acceptor capacity (EAC) and EEC (EDC + EAC), but was linear correlation with |EDC-EAC| that can characterize the extent of HFCs reacting with PMS. The higher the |EDC-EAC| is, the higher the catalytic activity of HFCs is. For carbonaceous materials, their catalytic activity was not proportional to EAC, but had good linear correlation with EDC and |EDC-EAC|. The discrepancy between carbon materials and carbonaceous materials could be due to the different activation mechanisms. Further analysis found that there was no correlation between EEC and the reactive species derived from PMS, indicating that the produced reactive species was not only controlled by EEC. This study firstly elucidated the correlation between EEC and catalytic activity of HFCs, and |EDC-EAC| could be used as an index for evaluating the catalytic activity of HFCs.

A critical and comprehensive review of the current status of 17β-estradiol hormone remediation through adsorption technology.

Even at low concentrations, steroid hormones pose a significant threat to ecosystem health and are classified as micropollutants. Among these, 17β-estradiol (molecular formula: C18H24O2; pKa = 10.46; Log Kow = 4.01; solubility in water = 3.90mgL-1 at 27°C; molecular weight: 272.4gmol-1) is extensively studied as an endocrine disruptor due to its release through natural pathways and widespread use in conventional medicine. 17β-estradiol (E2) is emitted by various sources, such as animal and human excretions, hospital and veterinary clinic effluents, and treatment plants. In aquatic biota, it can cause issues ranging from the feminization of males to inhibiting plant growth. This review aims to identify technologies for remediating E2 in water, revealing that materials like graphene oxides, nanocomposites, and carbonaceous materials are commonly used for adsorption. The pH of the medium, especially in acidic to neutral conditions, affects efficiency, and ambient temperature (298K) supports the process. The Langmuir and Freundlich models aptly describe isothermal studies, with interactions being of a low-energy, physical nature. Adsorption faces limitations when other ions coexist in the solution. Hybrid treatments exhibit high removal efficiency. To mitigate global E2 pollution, establishing national and international standards with detailed guidelines for advanced treatment systems is crucial. Despite significant advancements in optimizing technologies by the scientific community, there remains a considerable gap in their societal application, primarily due to economic and sustainable factors. Therefore, further studies are necessary, including conducting batch experiments with these adsorbents for large-scale treatment along with economic analyses of the production process.

Rapid and Up‐Scalable Flash Fabrication of Graphitic Carbon Nanocages for Robust Potassium Storage

AbstractGraphitic carbon nanocages (CNCs) have garnered attention as viable candidates for potassium storage, primarily due to their notable crystallinity, large surface area, and rich porosity. Yet, the development of a rapid, scalable, and economically feasible synthesis approach for CNCs persists as a formidable challenge. This study presents a rapid (millisecond‐scale) and scalable (gram‐scale) method for fabricating mesoporous CNCs characterized by high purity and orderly graphitic structures, utilizing the flash Joule heating technique. Employed for potassium storage, the CNC electrode developed herein exhibits exceptional performance metrics, including initial capacity, rate capability, and cycling stability, surpassing numerous carbonaceous materials previously documented. Impressively, it delivers a high initial capacity of 312.3 mAh g−1 at 0.1 A g−1, maintains 175.1 mAh g−1 at a high rate of 2.0 A g−1, and retains 219.6 mAh g−1 over 1000 cycles at 1.0 A g−1. Molecular dynamics simulations and in situ characterizations are employed to elucidate this robust behavior. This work underscores the significant advantages of the flash Joule heating technique in synthesizing carbonaceous materials for potassium storage applications.

Mechanically robust and conductive Ti5Te4/P@C composite materials as promising lithium-ion battery anodes

An urgent need has emerged to develop lithium-ion battery anodes that exhibit high reversible capacity and rate performance surpassing carbonaceous materials. Si-based composites have been investigated extensively. However, in this study, we explored another potential alloy anode consisting of Te and phosphorus without Si. Herein, we present a novel composite material, Ti5Te4/P@C, as an anode for lithium-ion batteries (LIBs). Tellurium, which exhibits good electrical conductivity and high volumetric capacity, and red phosphorus, which exhibits high theoretical capacity, were selected as potential anode materials. To overcome the common drawbacks of the two materials, including the vigorous expansion of volume, electrochemically inactive materials, such as titanium and carbon, were introduced as matrix buffers. Te, Ti, red phosphorus, and C were synthesized using a three-step high energy ball milling (HEBM) technique, that is, stepwise synthesis of (1) Ti and Te, (2) red phosphorus, and (3) carbon. The developed Ti5Te4/P@C composites revealed that the introduction of red P led to the generation of additional pure Te in the Ti5Te4/P@C composites, which was owing to the different binding interactions between Ti, Te, and red P, as confirmed by DFT calculations. Among the developed Ti5Te4/P@C anodes, Ti5Te4/P(30 wt%)@C exhibited outstanding cyclability and high rate performance (440 mAh g−1 at 300 mA g−1 after 500 cycles). To confirm the electrochemical responses and Li+ ion diffusion mechanisms, CV and GITT analyses were performed. Based on the electrochemical characteristics, the superior electrochemical performance of the Ti5Te4/P@C anodes can be ascribed to the well-defined composite structure, including the high electrical conductivity of Te, high theoretical capacity of red P, and effective buffering agents of Ti as a mechanical supporter and conductive C, which enable a pseudocapacitive response, providing better reversibility. Therefore, the Ti5Te4/P@C composite materials are viable anodes for high-performance LIBs.

Synergistic interactions between cellulose and plastics (PET, HDPE, and PS) during CO2 gasification-catalytic reforming on Ni/CeO2 nanorod catalyst

CO2 gasification-reforming is a promising approach for the transformation of carbonaceous materials into CO-rich syngas. Within municipal solid waste and agricultural waste streams, plastics are commonly found intermixed with biomass waste. This study delves into the CO2 gasification-reforming of biomass (cellulose) and various plastics (PET, HDPE, and PS) using a self-built online weighing fixed bed reactor and a two-stage fixed bed reactor. During the gasification-reforming of cellulose-plastic mixtures without the catalyst, the experimental gas production rate of cellulose slightly decreased, with the peak of gas production migrating to a higher temperature range. This phenomenon can be attributed to the molten plastic adhering to the cellulose surface, which impeded heat and mass transfer essential for cellulose decomposition. Furthermore, the gas production from plastics was suppressed in the mixtures, likely due to the interference of cellulose char in the decomposition of plastics. The incorporation of 2%Ni/CeO2 catalysts not only augmented gas yields and production rates but also emphasized the synergistic interactions. For the cellulose-HDPE mixture, the total gas yield was reduced by 14.9 mmol gsample−1 relative to the theoretical value. Given that HDPE possessed the highest decomposition temperature, the synergistic interaction was predominantly driven by the inhibitive nature of cellulose char. In contrast, the total gas yields for cellulose-PET and cellulose-PS mixtures increased by 8.7 mmol gsample−1 and 13.3 mmol gsample−1, respectively. The free radicals emanating from cellulose could trigger the decomposition of volatile components from plastics. Concurrently, the decomposition products of plastic could serve as hydrogen donors to stabilize the volatiles of cellulose. The interactions primarily affect the volatiles and tar components of the mixtures. The catalysts amplified gas yields by facilitating the CO2 reforming of tar, therefore, the synergistic interaction became evident upon catalyst addition. Gas chromatography-mass spectrometry analyses of the tar also corroborated the described interaction mechanisms between cellulose and plastics. Thermogravimetric analysis of used catalysts indicated that the synergistic action between cellulose and plastic could effectively diminish coke deposition, thereby preventing swift catalyst deactivation.

The application of machine learning methods for prediction of heavy metal by activated carbons, biochars, and carbon nanotubes

Carbonaceous materials are commonly used as adsorbents for heavy metals. The determination of the adsorption capacity needs time and energy, and the key factors affecting the adsorption capacity have not been determined. Therefore, a new and efficient method is needed to predict the adsorption capacity and explore the decisive factors in the adsorption process. In this study, three tree-based machine learning models (i.e., random forest, gradient boosting decision tree, and extreme gradient boosting) were developed to predict the adsorption capacity of eight heavy metals (i.e., As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) on activated carbons, biochars, and carbon nanotubes using 3674 data points extracted from 151 journal articles. After a comprehensive comparison, the gradient boosting decision tree had the best performance for a combined model based on all data (R2 = 0.9707, RMSE = 0.1420). Moreover, independent models were developed for three datasets classified by the adsorbent and eight datasets classified by the heavy metals. In addition, a graphical user interface was built to predict the adsorption capacity of heavy metals. This study provides a novel strategy and convenient tool for the removal of heavy metals and can help to improve the removal efficiency of heavy metals to build a healthier world.

Use of Carbon-Based Additives in Bio-Electrochemically Assisted Anaerobic Digestion for Cheese Whey Valorisation

This study explores the possibility of utilising electrochemically assisted anaerobic digestion supplemented with carbon-based materials to stimulate methanogenesis. Two different carbonaceous materials—commercial activated carbon (AC), and pyrolysed argan (PA, derived from argan shells)—were employed as supplements, with cheese whey (CW) being used as the substrate. Methane production slightly increased in the electrochemically assisted digesters, potentially translating into a 2–4% increase in the output of industrial digesters. In addition, reactors supplemented with PA also exhibited better production rates (496–508 L·kgVS−1), although there was no observed improvement in the quantity of biogas at the end of the biodegradability experiment. In contrast, when commercial AC was used as the supplement, the start-up phase was accelerated (5 days), although methane productivity decreased (273–352 L·kgVS−1). These observations were supported by microbiological analyses, demonstrating that the reactors with the poorest performance (those supplemented with AC) experienced the most significant decrease in both archaeal and bacterial populations.