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Isothermal chemical conversion of biomass pellets under the atmospheres of Ar, CO2 and O2 were conducted in this study to explore the effects of atmosphere and temperature on the gaseous releasing process and kinetics, and the structure of the solid char/ash products. Results showed that the gas production was promoted while the solid yield was decreased with the raising temperature. The CO2 reaction with char during gasification process mainly happened after 800 °C that the CO formation lasted for a longer time than pyrolysis. The surface area of char under CO2 atmosphere was increased to 215.57 m2/g with the increased temperature to 800 °C, but it was sharply reduced to 5.10 m2/g when the temperature further raising to 900 °C due to the destroyed carbon skeleton. The CO2 formation was largely promoted with a low activation energy of 11.98 kJ/mol during O2 oxidation process. Compared with the crystal structure of solid residues obtained under Ar and CO2 atmospheres, O2 oxidation process resulted in more complex crystal peaks with the main compositions of SiO2, K2SO4, and CaO. This study should be helpful to further understand the thermal conversion of biomass in a complex reaction atmosphere.

A CO2 -mediated hydrogen storage energy cycle is a promising way to implement a hydrogen economy, but the exploration of efficient catalysts to achieve this process remains challenging. Herein, sub-nanometer Pd-Mn clusters were encaged within silicalite-1 (S-1) zeolites by a ligand-protected method under direct hydrothermal conditions. The obtained zeolite-encaged metallic nanocatalysts exhibited extraordinary catalytic activity and durability in both CO2 hydrogenation into formate and formic acid (FA) dehydrogenation back to CO2 and hydrogen. Thanks to the formation of ultrasmall metal clusters and the synergic effect of bimetallic components, the PdMn0.6 @S-1 catalyst afforded a formate generation rate of 2151 molformate molPd-1 h-1 at 353 K, and an initial turnover frequency of 6860 mol H2 molPd-1 h-1 for CO-free FA decomposition at 333 K without any additive. Both values represent the top levels among state-of-the-art heterogeneous catalysts under similar conditions. This work demonstrates that zeolite-encaged metallic catalysts hold great promise to realize CO2 -mediated hydrogen energy cycles in the future that feature fast charge and release kinetics.

As global warming and climate change become perceived as significant, the release of greenhouse gases (GHGs) stored in the earth's polar regions is considered a matter of concern. Here, we focused on exploiting GHGs to address potential global warming challenges in the north polar regions. In particular, we used CO2 as a soft oxidant to recover energy as syngas (CO and H2) and to produce biochars from pyrolysis of peat moss. CO2 expedited homogeneous reaction with volatile matters from peat moss pyrolysis, and the mechanistic CO2 role resulted in the conversion of CO2 and peat moss to CO at ≥530 °C. Steel slag waste was then used as an ex situ catalyst to increase reaction kinetics, addressing the issue of the role of CO2 being limited to ≥530 °C, with the result where substantial H2 and CO formation was achieved at a milder temperature. The porosity of biochars, a solid peat moss pyrolysis product, was modified in the presence of CO2, with a significant improvement in CO2 adsorption capacity compared to those achieved by N2 pyrolysis. Therefore, CO2 has the potential to serve as an initial feedstock in sustainable biomass-to-energy applications and biochar production, mitigating atmospheric carbon concentrations.

To help minimize the negative impact of chemical fertilizers on the environment, recycle nitrogen and phosphorus nutrients of anaerobic digestate and reduce loss of nutrients via leaching, an eco-friendly slow-release fertilizer was prepared through recovery of nitrogen and phosphorus nutrition from digestate using superabsorbent fibers extracted from soybean curd residue as an adsorbent. The preparation method was proposed, and the fiber composite-based adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The successful incorporation of N and P into the fiber composite-based adsorbent via adsorption was confirmed by results of these analyses. The prepared fertilizer showed a relatively high N content (3.65 wt%) and a limited P content (0.14 wt%). Also, the swelling capacity as well as water retention capability of the obtained fiber composite-based adsorbent were evaluated. The release behavior of N and P from impregnated fiber composites was examined and was found to be partially in good accordance with the standard of the Committee of European Normalization, showing good slow-release and water-retention properties. Furthermore, in order to assess the fertilizer quality of the prepared materials, the effects of different fertilizers (commercially available fertilizer and prepared slow-release fertilizer) on tomato plant growth and soil microbial communities were investigated. The obtained results demonstrated the potential of fiber composite-based slow-release fertilizer system for recycling N and P nutrition from digestate, improving the effectiveness of fertilizer as well as protecting the environment.

Surface-modified poly( d , l -lactic-co-glycolic acid) PLGA nanoparticles (NPs) were fabricated via nanoprecipitation for obtaining therapeutic concentration of paclitaxel (PTX) in brain tumor. The cellular uptake and cytotoxicity of NPs were evaluated on C6 glioma cells in vitro, and BALB/c mice were used to study the brain penetration and biodistribution upon intravenous administration. Results showed that by finely tuning nanoprecipitation parameters, PLGA NPs coated with surfactants with a size around 150 nm could provide a sustained release of PTX for >2 weeks. Surface coatings could increase cellular uptake efficiency when compared with noncoated NPs, and d -α-tocopherol polyethylene glycol 1000 succinate (TPGS) showed the most significant enhancement. The in vivo evaluation of TPGS-PLGA NPs showed amplified accumulation (>800% after 96 h) of PTX in the brain tissue when compared with bare NPs and Taxol®. Therefore, PLGA-NPs with PLGA-TPGS coating demonstrate a promising approach to efficiently transport PTX across blood-brain barrier in a safer manner, with the advantages of easy formulation, lower production cost, and higher encapsulation efficiency.

Bio-heavy oil (BHO), a crude mixture of fatty acids (FAs) and mono-, di-, and triglycerides unavoidably generated as waste during biodiesel production processes, is an alternative replacement of petro-heavy oil as a fuel for power generation. It is reported for the first time that upgrading the quality of raw BHO (lowering the acid value (AV) of BHO) can be achieved via a low-pressure non-catalytic esterification process. Esterification of the FAs contained in raw BHO on solid acid catalysts (tungsten trioxide and niobium pentoxide) were investigated by comparison with the non-catalytic method. The AV of raw BHO can be successfully reduced from 116 to ∼38 in 2 h under a low pressure (0.1 bar) via the non-catalytic esterification process. Catalytic esterification with Nb2O5 or WO3 showed similar performance to the non-catalytic esterification. It can be suggested a possibility to make a high-quality renewable fuel (e.g., BHO with a low acid value) for power generation from inexpensive feedstock.

Rapid depletion of fossil fuel and CO2 mitigation are two major challenges in the modern society. CO2 gasification of carbon-neutral biomass could be an attractive technology to cope up these two emerging problems. Replacing conventional gasifying agent air with CO2 could reduce the fraction of undesired N2 in the gas products because CO2 behaves as inert gasifying agent under low temperature and could be converted to CO at high temperature range. However, most researches on CO2 gasification are limited at the lab-scale level due to the endothermic feature of Boudouard reaction. In this work, a feasibility study of small-scale autothermal gasification using 15% CO2 and 85% air was conducted and compared with traditional air gasification. Prior to that, a lab-scale study of gasification behaviors, under N2, air and CO2 agents, were performed. It was found that using CO2 as gasification oxidant could produce comparable energy (6.67 kJ/g feedstock) to air gasification (7.45 kJ/g feedstock) at equivalent condition (800 °C, 40 min). The pH of biochar obtained under CO2 condition at 800 °C was measured to be 10.63 while the pH of biochar derived by air gasification at the same temperature could reach 12.32. In addition, a small-scale gasification experiment with 15% CO2 addition was successfully conducted in a downdraft autothermal reactor. The results showed CO production was greatly enhanced while CH4 generation was suppressed owing to Boudouard reaction and CO2 dry reforming. Cold gas efficiency and carbon conversion efficiency were both enhanced by 5.8% and 6%, respectively, with CO2 addition. Meanwhile, particulate matters (PM) emitted from both air gasification and 15% CO2 gasification experiments were measured. It was found that under the same equivalence ratio (ER), 75.4% less particle number concentration was emitted during 15% CO2 gasification compared to air gasification.

Compared to pyrolysis biochar (PBC), gasification biochar (GBC) differs in both composition and surface functionalities due to the use of an oxidizing purging gas. This work compares the effect of using PBC and GBC as soil amendments on the soil properties, trace metal bioavailability, soil microbial activity, and soil dissolved organic matter (DOM). Biochar-driven reduction of bioavailable metals does not necessarily result in a positive impact on the soil microbial growth. The DOM in the soil was strongly related to the soil microbial activity, as revealed by the strong correlation between the soil dehydrogenase activity (DHA) and soil dissolved organic carbon (r = 0.957, p 0.01). Three identified fluorescent components (C1, C2, C3) in the soil DOM were closely associated with the soil microbial activity, for instance, with a clear positive correlation between the soil DHA and C1 (r = 0.718, p 0.05) and a significant negative correlation between the total bacterial fatty acid methyl ester content and C3 (r = -0.768, p 0.05). The bioavailability of Cd and Zn is not only related to the pH and surface functionalities of the biochar, but also to its aromatic carbon and inorganic mineral composition. This study further demonstrates that a fluorescence excitation-emission matrix coupled with parallel factor analysis is a useful tool to monitor changes in the soil quality after application of biochar, which is greatly relevant to the soil biota.

This study assessed the developmental toxicities of water-soluble carbon black wastes (CBW) extract (1:5, w/v) in zebrafish embryos (Danio rerio). Acute embryonic toxicity was performed following OECD guideline 236. Analysis using ICP-OES revealed that nickel (Ni) and vanadium (V) were predominant in CBW. Embryos exposed to CBW exhibited developmental delay, along with pericardial and yolk sac edemas. Malformed heart chambers were found in the CBW-exposed embryos and heart rates were significantly reduced since 48 h post fertilization (hpf). After RT-qPCR analysis, two cardiac forming-related genes, amhc and nppa responsible for atrial cardiac myofibril assembly and cardiac muscle cell proliferation, were up-regulated after 96 hpf. The increased mortality and delayed yolk-sac development appeared related to CBW-induced decrease in pH to about 5.5. Individual treatments of Ni and V did not cause identical toxic effects as CBW showed. At 100 ppm, V had a pH of approximately 5.5, causing developmental delay and pericardial edema in zebrafish embryos. At the same pH, combined Ni and V induced morphological anomalies and reduced heart rates similar to CBW-exposed embryos. Conclusively, this study demonstrates that environmental runoff is a serious concern, and thus, CBW incineration bottom ash should be treated carefully before disposal in landfills.

Online measurements of key information such as the decomposition stages of biomass gasification/pyrolysis in a fixed-bed reactor is currently limited with existing technologies. In this study a proof of concept for using Electrical Capacitance Tomography (ECT) for monitoring the decomposition stages of woody biomass is done. In practice, ECT measures the permittivity of the material under test. Therefore, the relation between the permittivity of the biomass in terms of the extent of thermal treatment is essential. Pyrolysis and gasification experiments were conducted to different extent of time and temperatures at a lab scale gasifier using wood chips. The permittivity of the samples was measured in-vitro using impedance analyzer at different excitation frequencies (20 kHz to 3 MHz). At a critical pyrolysis temperature of 700 °C the permittivity starts to increase significantly. In addition, for air-aided gasification the permittivity was found to reach its maximum in holding time of 10 or 30 min. Further examination of these samples in an ECT sensor revealed the same trend, implying that the permittivity results can be used for converting ECT reading to decomposition state. Chemical characterizations were done via elemental, thermogravimetry analysis, X-ray diffraction and Fourier transform infrared (FTIR) Spectroscopy. It was found that graphitization of the material is a prominent factor that control the increase of the permittivity. Analyzing quantitatively the aromatic and aliphatic carbon from the FTIR results disclose that it has a strong relation to the permittivity change when the aromatic carbon is higher than 95%. Therefore, in this range, it was possible to correlate these two parameters by an inverse relation which lead to a good match under frequencies higher than 200 kHz.

In this work, we firstly examined the technical feasibility of geopolymer synthesis from the coal fly ash with high iron oxide (48.84 wt.%) and calcium oxide (22.15 wt.%) contents. The heat resistance of geopolymer was represented by the dry weight loss which ranged from 2.5 to 4.9% and was better than that (11.7%) of OPC. However, the high iron oxide content made the acid resistance (13–14%) of geopolymer inferior to OPC. The economics of geopolymer production changes significantly upon the variation in the arrangement of material use and geopolymer price. The costs of Na2SiO3 and NaOH and the benefit of geopolymer selling were the major factors affecting the economic feasibility of geopolymer production. When the Na2SiO3 price was around 400 USD/ton, the geopolymer production will be profitable even if the geopolymer price was as low as 50 USD/ton. It is possible to improve the economics of geopolymer production by varying the arrangement of material use while not impairing the performance of geopolymer.

A granular composite sorbent (LC-CF) was synthesized from acid-leached carbon waste using chitosan and FeCl3, and its feasibility for nitrate and phosphate removal was investigated in this study. The sorption data was well described by the pseudo-second-order kinetic model, and the maximum sorption capacity of LC-CF predicted by Langmuir model for nitrate and phosphate were 41.90 mg g−1 and 62.72 mg g−1, respectively. In comparison, LC-CF had a greater affinity for phosphate and exhibited a better reusability for nitrate removal during the sorption-desorption cycles. Ion exchange, electrostatic interaction, and hydrogen bond are the potential sorption mechanisms. In light of the cost-benefit analysis, the proposed treatment of carbon waste was more economically feasible as compared with existing incineration scheme. These results illuminated that synthesis of granular sorbent with carbon waste could achieve the harmless disposal of hazardous industrial waste as well as the production of value-added sorbent for water treatments.

Anaerobic digestion produces large quantities of digestate as a by-product, which can potentially be applied as an organic fertilizer, but untreated anaerobic digestate (AD) may contain phytotoxins and the large volume of AD makes transportation and storage difficult. This study explored two relatively inexpensive processing methods to improve the agronomic performance of AD as a fertilizer via vegetable cultivation experiments. We first investigated the effect of dilution on AD’s performance using four leafy vegetables (Chinese spinach, water spinach, Chinese cabbage and lettuce). The optimal concentrations of the AD were 20–40% (v/v in 250 mL applications per single-plant pot) for all four vegetables based on shoot fresh weight and comparable to the control treatment using commercial fertilizer. AD application also introduced Synergistetes bacteria into the growing medium, but the overall bacterial diversity and composition were similar to those of the control treatment. Considering the nutrient separation in the liquid and solid fractions of AD and the need to reduce the volume, we then experimented with the recovery of nutrients from both the liquid and solid fractions by filtering AD using two types of wood-based biochar (100 g biochar: 1 L AD) before applying the AD-biochar residues as side dressing at 1% (w/w). Both types of biochar achieved yields comparable to the treatment using a commercial fertilizer for the three vegetables tested (kale, lettuce and rocket salad). Our results show that dilution and biochar filtration can improve the agronomic performance of AD, making it a sustainable substitute for commercial fertilizer.

The remediation of oil spills and treatment of oily wastewater remains challenging to cope with nowadays. This has caused a surge in demand on adsorbent materials with multi-functionalities to effectively separate oils and nonpolar solvents from water. A superhydrophobic composite aerogel prepared from industrial waste-derived leached carbon black waste (LCBW) and polyvinyl alcohol (PVA) was developed in this work via conventional freeze-casting followed by surface coating. The composite aerogel was ultralight and porous with porosity >85% and tunable density ranging between 0.015 and 0.065 g/cm3. It was found that the embedded LCBW in the PVA network is crucial to impart superhydrophobicity and superoleophilicity to the aerogel as it enhances the surface roughness. Wettability test showed that composite aerogel prepared from 0.5 wt% PVA at PVA/LCBW ratio of 1 exhibited the highest water contact angle (156.7 ± 2.9°). LCBW also improved the thermal stability of the composite aerogel. With its superior selectivity, PVA/LCBW aerogel was used as selective adsorbent for a variety of oils and organic solvents. The adsorption test showed that the composite aerogel exhibited an adsorption capacity up to 35 times its original weight and could be reused repeatedly and easily recovered through a simple drying method.

In recent years, combination therapy has emerged as the cornerstone of clinical practice in treating glioblastoma multiforme. However, their ability to trigger and leverage the body's adaptive immunity has rarely been studied. Tumour heterogeneity, the presence of the blood-brain barrier, and an immunosuppressive tumor microenvironment play a crucial role in the 90% local tumor recurrence post-treatment. Herein, we report an improved combination therapy approach capable of stimulating an immune response that utilizes Light responsive antigen-capturing oxygen generators (LAGs). The engineered LAGs loaded with a non-genotoxic molecule, Nutlin-3a, and a photosensitizer, Protoporphyrin IX, can release the payload on-demand when exposed to light of a specific wavelength. The in-situ oxygen generation capability of LAGs enables tumor oxygenation enhancement, thereby alleviating the tumor hypoxia and enhancing the efficacy of chemo-photodynamic therapy. Furthermore, by modulating the surface properties of LAGs, we demonstrated that the tumor-derived protein antigens released can be captured and retained in-situ, which improves antigen uptake and presentation by the antigen-presenting cells. Dual drug-loaded LAGs (DD-LAGs) upregulated the expression of cell surface CD83 maturation and CD86 costimulatory markers on monocyte-derived-dendritic cells, suggesting intrinsic immune adjuvancy. In the presence of 3D printed hypoxic U87 spheroids (h-U87), DD-LAGs induced cancer cell death, upregulated IL-1β, and downregulated IL-10 resulting in CD3+, helper CD4+, and cytotoxic CD8+ proliferation. Finally, we have investigated convection-enhanced delivery as a potential route of administration for DD-LAGs. Our work presents a novel strategy to induce tumor cell death both during and post-treatment, thereby reducing the possibility of recurrence.

Biochar as a biomass derived, low cost, carbon conductive material is considered as an important supplement in the anaerobic digestion (AD) of organic matter. It functions as an electrical grid to ...

Fly ash represents a kind of finely divided solid waste which is derived from industrial or municipal waste incineration and contains various metal elements. In this work, we focus on the waste-to-resource conversion of one fly ash which is generated from the incineration of petroleum coke gasification waste. The leaching behaviors and waste conversion of this fly ash to value-added products under different treatments were investigated. The majority of the identified elements in leachate demonstrated different leaching patterns as the species of leached element from fly ashes depend on the chemical properties of leaching agents. Moreover, A pathway is developed to harvest toxic vanadium from this fly ash, and the vanadium-containing leachate can be further converted into electrolyte for vanadium redox flow battery (VRFB). The vanadium electrolyte was synthesized by using fly ash leachate as the resource materials in two different ways afterwards: reducing vanadium in the leachate directly (electrolyte from leachate) and synthesizing V2O5 from leachate as the intermediate product (electrolyte from leachate-derived V2O5). The electrochemical behavior and performance of these electrolytes were analyzed to investigate the feasibility of these approaches. The measurement of electrochemical performance proves that the electrolyte from leachate-derived V2O5 is comparable to the standard electrolyte in terms of columbic efficiency (CE), energy efficiency (EE) and stability. Based on experimental results, our research provides a potential solution for the establishment of vanadium flow battery plant. Cost-benefit analysis proves that the payback period of electrolyte synthesized from alkaline leachate and leachate-derived V2O5 is 2.1 years and 1.0 year, respectively.

The occurrence of emerging organic contaminants (EOCs) such as chemicals in personal care products, pharmaceuticals, plasticizers, etc. in surface waters is a growing global concern. The discharge of most EOCs is not regulated, and EOCs have been shown to be toxic to both human and aquatic life even at low concentrations. In this work, acid-leached carbon black waste (LCBW), a carbonaceous residue from petroleum refineries, was investigated as a potential waste-derived adsorbent for the removal of EOCs. Ciprofloxacin hydrochloride, (CIPRO, antibiotic), sulfamethoxazole (SULFA, antibiotic), acetaminophen (ACET, pharmaceutical), bisphenol A (BPA, plasticizer) and N,N-diethyl-3-methylbenzamide (DEET, insect repellent) were chosen as the target EOCs owing to their presence in relatively high concentrations in surface waters as well as in the influent and effluent of wastewater treatment plants. LCBW, with a specific surface area of 409 m2/g, demonstrated 90–99% removal of 10 ppm CIPRO, BPA, and ACET and 70–80% removal of 10 ppm SULFA and DEET in tap water. Adsorption was rapid, particularly for CIPRO, BPA, and ACET, wherein >85% of the adsorption occurred within 1 h of contact time. To illustrate the potential of LCBW as an adsorbent in different physical forms, ∼3 mm spherical beads of LCBW encapsulated within carboxymethyl cellulose matrix were prepared by a facile ionic gelation method and their adsorption performance was demonstrated.

Light irradiation is considered an ideal non-invasive stimulus that enables precise tumour treatment with flexible, facile, and spatiotemporal control. Photodynamic therapy (PDT) is an important clinically relevant therapeutic modality that has proven to compensate for the reduced therapeutic efficacy of conventional chemotherapy. However, oxygen consumption during PDT can result in an inadequate oxygen supply which reduces photodynamic efficacy. In our quest to circumvent the limitations of chemotherapy and photodynamic therapy, we have engineered a robust and smart "all-in-one" nanoparticle-based drug delivery system capable of overcoming biological barriers and leveraging on several synergistic cancer cell killing mechanisms. The fabricated Targeted Micellar Nanoprobe (TMNP) had exceptionally high encapsulation efficiencies of a hydrophobic drug simvastatin (SV) and a photosensitizer protoporphyrin IX (PpIX) due to the ℼ-ℼ stacking of the aromatic groups of SV and PpIX and strong hydrophobic interactions with the alkyl chains of the carrier. In-vitro results demonstrated that TMNP exhibited excellent colloidal stability, biocompatibility and drug retaining capability in physiological condition. Under light irradiation, TMNP causes the accelerated generation of reactive oxygen species (ROS) which subsequently damages the mitochondria. On further evaluation of the mechanisms behind the superior anti-cancer effect of TMNP, we concluded that TMNP causes synergistic apoptosis and necrosis along with cell cycle arrest at the G1-S phase and elicits anti-angiogenic effects. Taking into consideration that these promising results on 2D monolayer cell cultures might not translate into similar results in animal models, we developed 3D multicellular tumour spheroids (MCs) as an intermediate step to bridge the gap between 2-D cell experiments and in-vivo studies. TMNPs showed enhanced penetration and growth inhibition on MCs. In addition, the modelling of the transport of TMNP in the tumour exhibited the improved effective delivery volume. Overall, TMNPs could potentially be used for image-guided delivery of the therapeutic payloads for precise cancer treatment.

Sewage sludge bottom ash (SSBA) from the incineration plant used for the production of construction materials possibly possess heavy metals which might cause a negative impact on human health. Considering biosafety, we investigated the toxicity effects of 0.5–2 mm (aggregate substitute) and

Disposal of nitrogen-containing sewage sludge (SS) via gasification leads to the formation of NOx precursors and NOx and ammonia emissions. Pretreatment of SS via hydrothermal carbonization (HTC) was shown to improve coalification, desulfurization, and deamination. In this study, we propose a combined hydrothermal pretreatment and CO2 gasification process for removal of nitrogen from SS and production of energy via the gasification of the pretreated SS. In the HTC process, around 50% of nitrogen contained in the sludge was removed. The derived hydrochar (HC) was subsequently fed for gasification using CO2 as a gasifying agent, which was characterized by the expected reduction in the formation of ammonia. We further improved the process by establishing cogasification of hydrochar with waste leaves. The improvement is believed to be due to the catalytic effect of Ca, present in plant leaves, on the gasification. Cold gas efficiency of the cogasification process of a 1/1 hydrochar/leaves blend by mass was en...

This study is a comparison of the effect of biochar produced by bioenergy systems, via the pyrolysis and gasification processes, on the immobilization of metals/metalloids in soil. Because the processes for these two techniques vary, the feedstocks undergo different heating regimens and, as a result, their respective char products exhibit different physico-chemical properties. Therefore, this study focuses on (1) the characterization of derivative biochar from the bioenergy system to understand their features and (2) an exploration of various biochar impacts on the mobility of As and Pb in contaminated soil. The results showed bioenergy biochars (BBCs) performed well in mitigating Pb extractability (1 M ammonium acetate) with a Pb immobilization >80%, but unfavorably mobilized the bioavailable As, likely because of electrostatic repulsion and ion exchange competition. The BBC surface functional group would chemically bond with the As and remain stable against the pH change. An increment in aromatic carbon would effectively enhance cation-π interaction for Pb immobilization. Nevertheless, an amendment with richer condensed structure and higher inorganic minerals (Ca2+, K+, Mg2+, and Na+) can lead to better performance in retaining Pb.

Phytoremediation is increasingly recognized as a cost-effective approach for remediation of heavy metal (HM) contaminated soils, whereas the derived HM-enriched hyperaccumulators must be properly harvested and disposed. In this study, gasification of Sedum alfredii was performed at a temperature series (300–900 °C) with different gasifying agents (N2, CO2 and air), then the transfer behaviors of zinc (Zn), cadmium (Cd), and lead (Pb) and the characteristics of the derived biochar and syngas were investigated. The high gasification temperatures and reducing atmosphere (N2) effectively enhanced the volatilization of Zn, Cd, and Pb, and the results from toxicity characteristic leaching process indicate that gasification greatly enhanced the stability and reduced the availability of HMs in S. alfredii. The CO2-derived biochars had moderate pH and greater stability, while the N2-derived biochars showed better energy density. The evolution of functional groups and crystalline phases in biochars were both influenced by the temperature, and the role of atmosphere was increasingly obvious at temperatures above 600 °C. As expected, biochars derived under N2 and CO2 both showed considerable sorption capacity for Pb (134.2–198.8 mg g−1) and Cd (38.1–186.8 mg g−1). CO2 atmosphere greatly enhanced the production of CO at higher temperatures (>700 °C), while N2 atmosphere favored the yield of H2 and CH4. These results imply that gasification could be a promising technique to achieve the separation of HMs from hyperaccumulator as well as the production of energy and multifunctional material, and this process is greatly affected by the gasification temperature and atmosphere.

A two-step fabrication process combining emulsification-solvent evaporation method for encapsulation of drug in PLGA microparticles followed by supercritical gas foaming was developed to produce drug-releasing biodegradable micro-porous foams. The encapsulation and release of model hydrophobic drug (Curcumin) and of model hydrophilic drug (Gentamicin) were investigated in this work. By utilizing a two-step fabrication process, a uniform dispersion of the drug in PLGA polymer matrix can be achieved and the method can be further adapted for the encapsulation of a wide range of active ingredient (both hydrophobic and hydrophilic) in biodegradable micro-porous scaffold. The in vitro release profile of the drug-encapsulated PLGA foam was studied over a period of 2 weeks and it was observed that the drug release profile can be engineered by the selection of different PLGA polymer blend, varying lactic to glycolic ratio and molecular chain length of the polymer, and by addition of compatible biodegradable polymer such as Polyethylene Glycol (PEG) to the polymer matrix.

In this study, microwave-assisted alkali pretreatment for brewers’ spent grain (BSG) waste was comprehensively investigated using Box-Behnken design under varying operating parameters, i.e. microwave power, pretreatment time and alkali/biomass (A/B) ratio. Both quantitative and qualitative characterization analysis such as crystallinity index (CrI), specific surface area (SSA), morphology and compositional analyses were conducted on pretreated samples. Standard biomethane potential (BMP) tests were performed for each pretreated sample to observe the biomethane enhancement after pretreatment. Under optimized conditions, it was observed that the pretreatment technique has facilitated removal of 46% of lignin and 38% of hemicellulose and improved the SSA of samples from 9.55 to 161.98 m2/g, contributing to 52% increase in BMP value. Meanwhile, mathematical models with correlation coefficients of 97.9% and 98.2% respectively were built to predict both the soluble chemical oxygen demand (COD) yield and BMP after pretreatment. Furthermore, a simplified concept of overall evaluation mechanism for pretreatment has been introduced, taking into account waste-removal, energetic and economic indices. Under the proposed evaluation mechanism, the caustic soda price was found to play a more important role than the prices of industry electricity and wholesale natural gas.

Convection enhanced delivery (CED) of chemotherapeutic drugs can successfully bypass the blood-brain barrier (BBB). However, the treatment efficacy is significantly variable in clinic owing to the absence of proper drugs and the lack of understanding on the local drug transport. In this study, mathematical modelling is employed to investigate the suitability of six chemotherapeutic drugs from the perspective of intratumoural transport, including fluorouracil, carmustine, cisplatin, methotrexate, doxorubicin and paclitaxel. The convection/diffusion/reaction model coupled with Darcy's law is applied to a 3-D realistic brain tumour model that is extracted from magnetic resonance (MR) images. The modelling demonstrates the advantages of CED in enhancing the convective flow of interstitial fluid and reducing the drug concentration dilution caused by the fluid loss from blood stream in the tumour region around the infusion site. The delivery outcomes of the drug in CED treatments are strongly dependent on its physicochemical properties. Convection is more effective in determining the transport of paclitaxel and methotrexate in brain tumour. Paclitaxel exhibits its superiority in drug penetration and accumulation, resulting in the largest effective delivery volume as compared to the other studied drugs. Nanocarrier and diagnostic ultrasound are able to enhance the drug penetration for achieving improved delivery outcomes. Results obtained in this study can serve as a guide for optimising CED treatment regimens.

Currently, industrial wastes are typically combusted at incineration plants, and the resulting ashes are sent to landfill. This practice raises issues, such as potential toxicity of the leachate to the environment, as well as the loss of valuable metals left in the waste. Therefore, from both economic and environmental standpoints, it is becoming increasingly important to recover valuable metals from industrial waste. In this work, a transformative recovery of vanadium (conversion nearly 100%) from leaching solutions of carbon black waste (metal leaching efficiency > 97%) which originates from oil refineries in Singapore, has been systematically studied. Interestingly, three distinctive alkaline earth vanadate nanomaterials were successfully synthesized from the leaching solutions by a facile hydrothermal process, that is, single-crystal calcium vanadate nanorods (Ca10V6O25) oriented along the [001] direction, strontium vanadate nanorods with ellipsoid-like assembly (Sr10V6O25), and barium vanadate polyhe...

The solar/autothermal hybrid gasifier (SAHG) is an attractive approach to provide continuous production of the syngas via coupling autothermal and solar gasification together, where the SAHG mainly includes fully solar, hybrid, and fully autothermal modes. An ICE CCHP system driven by the SAHG with an indirectly irradiative two-cavity reactor introduced conceptually and investigated thermodynamically. Considering the effects of solar flux inputs and various reactant ratios, a zero-dimensional steady-state model of the SAHG was established by using Gibbs free energy minimization, and was validated with the reported data. The optimal steam-to-feedstock and oxygen-to-feedstock ratios has been achieved based on the restrictions of temperature over 1000 K and minimization of steam input. The results of two consecutive days indicate mole flow rates of H 2 and CO were increased by over 38.8% and 11.8%, respectively, leading to an increment in LHV s by 51.7%. An increment in primary energy ratio by 11.5% can be achieved by using the SAHG-CCHP system. The yearly assessment of the SAHG-CCHP system shows that the yearly average increments in heat, power, and cooling for the SAHG system were reached by 19.5%, 23.8%, and 4.5%, respectively. A yearly average increment of 14.2% in primary energy ratio can be obtained under the solar radiation condition of Singapore.

Containment of oil spills in aquatic bodies and treatment of oily wastewater are necessary to mitigate oil pollution. Synthetic oil sorbents are commonly used for managing oil spills and while they are effective, their usage introduces a considerable amount of non-biodegradable plastic into the environment. In an effort to develop an inexpensive sorbent by reutilizing solid wastes for a sustainable future, this study investigates the fabrication of a composite oil sorbent from used polyethylene terephthalate bottles and waste carbonaceous residue from the gasification of oil refinery bottoms via an energy efficient phase inversion method. The composite sorbent demonstrated oil sorption capacity of ∼ 8 g/g, which is comparable to some commercially available adsorbents, and excellent retention capacity for mineral, paraffin and crude oils of different viscosities. Furthermore, the composite is able to remove oil from mineral or paraffin oil-in-water emulsions by sorption, with an efficacy of > 99.7 %, indicating its promising application in the treatment of industrial oily wastewater. Cost analysis shows that this waste-derived composite can be produced commercially at a competitive price.

A 7-kWth indirectly irradiated solar gasifier with a clapboard-type internally circulating fluidized bed was developed and conducted experimentations under concentrated solar radiation. The solar CO2 gasification of charcoal produced by low-temperature pyrolysis was examined under a 28-kWe high-flux solar simulator considering different operating conditions. The effects of CO2:C and feedstock mass on the key performance indicators e.g. the carbon conversion, energetic upgrade factor, and solar conversion efficiency were investigated by using alumina granules as an inert bed material. The first-hand, reproducible experimental data indicated the highest values of the average carbon conversion of 0.53 ± 0.04, energetic upgrade factor of 0.883 ± 0.03, solar conversion efficiency of 5.3 ± 0.6% were achieved under the operating conditions of 80 g charcoal, 1.5 kg alumina particles, and 2 L/min CO2. The feedstock mass significantly affected the solar conversion efficiency but no notable effect on the energetic upgrade factor was observed. The solar conversion efficiency can be significantly improved via fully replacing inert alumina particles by feedstock, adding a continuous feeder, and optimizing the superficial velocity to minimize particle entrainment.

This study focused on conversion of algal biomass to bio-oil through in-situ catalytic fast pyrolysis. In particular, novel Ni2P-loaded and unmodified (zeolite, activated carbon and chicken manure biochar) catalysts were evaluated to determine their effect on in-situ upgrading of algal pyrolysis products. Among the catalysts evaluated, Ni2P-loaded zeolite achieved the highest bio-oil hydrocarbon (34.97 %) and calorific value (32.66 MJ/kg), and the lowest O/C (0.075) and N/C (0.074) ratios. There was a 137 % increase of the aliphatic hydrocarbon fraction and a 72 % increase of the biochar specific surface area (SSA) with the loading of Ni2P to zeolite. Additionally, unfavourable major oxygen- and nitrogen-containing compound, phytol and tetradecanamide, decreased seven- and six-fold, respectively, compared to the non-catalytic baseline case. Ni2P-loaded biochar achieved a reduction in the bio-oil acidity from a pH of 4.52–6.78 and a 41 % decrease of the carboxylic acids content. Biochar produced from the zeolite formulations exhibited especially favourable sorbent quality with SSA greater than 500 m2/g. According to the proposed catalytic mechanism, the generation of n-heptadecane and hexadecanamide may be due to the decomposition of phytol and tetradecanamide, and the catalytic activity was correlated to the pore size of the catalyst (22.22 A). Direct addition reactions were the dominant pathway in the formation of liquid hydrocarbons. These results suggest that it is feasible to develop an in-situ multi-catalyst system to achieve high-quality bio-oil production. Thus, the development of novel Ni2P-loaded catalysts addressed a promising approach for biomass conversion into hydrocarbon-rich products with low risk to the environment.

Disposal of animal manure in an environmentally friendly way is a severe challenge for megacities. At the gasification temperature of chicken manure around 900 °C, the CO2 gasification product is abundant in hydrogen. The co-gasification of chicken manure with petcoke increased the hydrogen content in syngas. The catalytic effect of chicken manure ash on petcoke gasification was investigated individually. The yield of CO in ash catalyzed gasification product of petcoke was more than 5 times higher than that in pure petcoke gasification product, which demonstrated the strong catalytic effect of chicken manure ash on gasification reaction. The microstructure of partially gasified petcoke particles demonstrated the effect of chicken manure ash on pore development. Reaction surface areas of petcoke also would be blocked when adding excess ash in petcoke for gasification. The high content of calcium and potassium contributed to the dramatically catalytic effect of chicken manure ash. The combustion of petcoke supplied enough heat for co-gasification process. Synergistic effect was achieved during co-gasification process of chicken manure and petcoke. The chicken manure waste was sustainably disposed and also was used as catalyst for gasification reaction.

A food waste treating system was proposed in this study by combining biochar-assisted high-solid anaerobic digestion and subsequent steam gasification of the digestate. The effect of solid level, biochar dosage in anaerobic digestion on the properties of biogas, syngas, and final biochar products were investigated. Results showed that at a high total solid level and biochar dosage of 25 g/L and 50 g/L, the accumulative methane yield reached 110.3 mL CH4/g VS and 126.7 mL CH4/g VS, respectively. From steam gasification of different digestates under 850 °C for 15 min, a maximum of 34.92 mmol/g for the hydrogen yield and 11.44 MJ/m3 for the higher heating value could be obtained for the syngas. Furthermore, the by-product produced from steam gasification was a nutrient-enriched porous biochar, which was suitable to be used as compost. This study demonstrated a pathway for food waste treating to produce methane-enriched biogas, hydrogen-enriched syngas, and nutrient-enriched biochar.

In this study, the conversion of fat, oil and grease (FOG) into fatty acid methyl esters (FAMEs) without pre-treatment of FOG is investigated. A thermally induced process to accomplish simultaneous esterification of free fatty acids (FFAs) and transesterification of lipids is introduced. Despite high contents of impurities in FOG (∼14 wt%), the maximum achievable yield of FAMEs on feedstock mass basis was >86% for 10 s reaction time without removal of impurities prior to the reaction while conventional acid catalyzed reaction only produced

Biomass conversion to value-added chemicals and fuels over heterogeneous catalysts is one of the top issues in green chemistry. This review focuses on recent advances in the application of solid catalysts for producing three prominent bio-based chemicals, hydroxymethylfurfural (HMF), levulinic acid (LA) and fatty acid methyl ester (FAME) from biomass materials, respectively. Our work highlights the perspectives and challenges during the conversion of actual biomass, including the impact of complex constituents and impurities of biomass on the solid catalysts, mass transfer limitation in the reactions, and the stability and deactivation of the solid catalysts. Transformation of solid catalysts from research to industrialization necessitates future work on identification of interactions between the catalysts and actual biomass, and comprehensive evaluation of the suitability of the catalysts in the reaction systems.

Electrostatic charge generation is a multivariable and complex issue whose working mechanism has never been fully understood. The objective of this paper is to investigate the effect of granule surface roughness on electrostatic charge generation. Two kinds of granule material, Polyvinyl chloride (PVC) and polypropylene (PP) were used with the granule size of 4 mm diameter, 2 mm height and the shape was cylinder or semi-cylinder. The working surfaces were grounded and roughness ranged from 0.140 to 8.600 μm. It was found that uneven surfaces tended to give rise to voids between two solids, where air stored in the voids was able to accelerate discharging. With the same roughness, PVC tended to generate more electrostatic charge than PP by one order of magnitude. For both materials, electrostatic charge generation first increased with surface roughness and then decreased. The maximum electrostatic charge generated was found to occur when the effects of interaction, contact area and voids discharging were at equilibrium. With the combined effect of humidity, surface roughness and contact area, highest electrostatics generation occurred near the mid-roughness tested in this work. Humidity had more effect on electrostatic charge generation as the granule working surface had lower roughness.

Background and Objective This study aimed to develop pH-responsive polylactide-glycolic acid co-polymer and chitosan (PLGA/chitosan) nanosphere as an inflammation-responsive vehicle and evaluate the potential of the nanosphere encapsulating metronidazole, an antibiotic, and N-phenacylthiazolium bromide (PTB), a host modulator, for treating periodontitis. Material and Methods PLGA/chitosan nanospheres were fabricated using oil-in-water emulsion method. Experimental periodontitis was induced on the rat maxillae, and the sites were randomly allocated to four treatment categories, including periodontitis alone (PR), periodontitis with nanospheres alone, nanospheres encapsulating metronidazole (MT) and nanospheres encapsulating PTB (PB). The ligature was retained until the animals were killed, and the treatment outcome was evaluated by the progression of periodontal bone loss (PPBL), inflammatory cell infiltration and collagen deposition. Results The encapsulated drug was released rapidly from the nanospheres without significant initial burst release at pH 5.5. Compared with group PR, PPBL was significantly reduced in groups MT and PB on day 4 (P

Owing to the presence of multidrug resistance in tumor cells, conventional chemotherapy remains clinically intractable. To enhance the therapeutic efficacy of chemotherapeutic agents, targeting strategies based on magnetic polymeric nanoparticles modified with targeting ligands have gained significant attention in cancer therapy. In this study, we synthesized transferrin (Tf)-modified poly(D,L-lactic-co-glycolic acid) nanoparticles (PLGA NPs) loaded with paclitaxel (PTX) and superparamagnetic nanoparticle (MNP) using a solid-in-oil-in-water solvent evaporation method, followed by Tf adsorption on the surface of NPs. The Tf-modified magnetic PLGA NPs were characterized in terms of particle morphology and size, magnetic properties, encapsulation efficiency and drug release. Furthermore, the cytotoxicity and cellular uptake of the drug-loaded magnetic PLGA NPs were evaluated in both MCF-7 breast cancer and U-87 glioma cells in vitro. We found that Tf-modified PTX-MNP-PLGA NPs showed the highest cytotoxicity effect and cellular uptake efficiency under Tf receptor mediation in both MCF-7 and U-87 cells compared to unmodified PLGA NPs and free PTX. The cellular uptake efficiency of Tf-modified magnetic PLGA NPs appeared to be facilitated by the applied magnetic field, but the difference did not reach statistical significance. This study illustrates that this proposed formulation can be used as one new alternative treatment for patients bearing inaccessible tumors.

Convection enhanced delivery (CED) is a promising method of anticancer treatment to bypass the blood–brain barrier. This paper is aimed to study drug transport under different CED operating conditions. The convection enhanced delivery of chemotherapeutics to an intact and a remnant brain tumour after resection is investigated by means of mathematical modelling of the key physical and physiological processes of drug transport. Realistic models of brain tumour and its holding tissue are reconstructed from magnetic resonance images. Mathematical modelling is performed for the delivery of carmustine and paclitaxel with different infusion rates, solution concentrations and locations of infusion site. Modelling predications show that drug penetration can be improved by raising the infusion rate and the infusion solution concentration. The delivery of carmustine with CED is highly localised. High drug concentration only can be achieved around the infusion site. The transport of paclitaxel is more sensitive to CED-enhanced interstitial fluid as compared to carmustine, with deeper penetration into tumour interior. Infusing paclitaxel in the upstream of interstitial fluid flow leads to high spatial averaged concentration and relatively uniform distribution. Results obtained in this study can be used to guide the design and optimisation of CED treatment regimens.

In Singapore, approximately 30t/day of carbon-based solid waste are produced from petrochemical processes. This carbon black waste has been shown to possess physical properties that are characteristic of a good adsorbent such as high external surface area. Therefore, there is a growing interest to reutilize and process this carbon black waste into secondary materials such as adsorbents. However, the carbon black waste obtained from petrochemical industries may contain heavy metals that are hazardous to human health and the environment, hence restricting its full potential for re-utilization. Therefore, it is important to examine the possible toxicity effects and toxicity mechanism of carbon black waste on human health. In this study, inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis showed that the heavy metals, vanadium (V), molybdenum (Mo) and nickel (Ni), were present in the carbon black waste in high concentrations. Three human cell lines (HepG2 cells, MRC-5 cells and MDA-MB-231 cells) were used to investigate the toxicity of carbon black waste extract in a variety of in vitro assays. Results from MTS assays indicated that carbon black waste extract decreased the viability of all three cell lines in a dose and time-dependent manner. Observations from confocal microscopy further confirmed this phenomenon. Flow cytometry assay also showed that carbon black waste extract induced apoptosis of human cell lines, and the level of apoptosis increased with increasing waste concentration. Results from reactive oxygen species (ROS) assay indicated that carbon black waste extract induced oxidative stress by increasing intracellular ROS generation in these three human cell lines. Moreover, induction of oxidative damage in these cells was also observed through the alteration of glutathione (GSH) and superoxide dismutase (SOD) activities. Last but not least, by treating the cells with V-spiked solution of concentration equivalent to that found in the carbon black waste extract, V was identified as the main culprit for the high toxicity of carbon black waste extract. These findings could potentially provide insight into the hazards of carbon black waste extract and its toxicity mechanism on human cell lines.

In this work, carbon black waste - a hazardous solid residue generated from gasification of crude oil bottom in refineries - was successfully used for making an absorbent material. However, since the carbon black waste also contains significant amounts of heavy metals (especially nickel and vanadium), chemical leaching was first used to remove these hazardous impurities from the carbon black waste. Acid leaching with nitric acid was found to be a very effective method for removal of both nickel and vanadium from the carbon black waste (i.e. up to 95% nickel and 98% vanadium were removed via treatment with 2M nitric acid for 1h at 20°C), whereas alkali leaching by using NaOH under the same condition was not effective for removal of nickel (less than 10% nickel was removed). Human lung cells (MRC-5) were then used to investigate the toxicity of the carbon black waste before and after leaching. Cell viability analysis showed that the leachate from the original carbon black waste has very high toxicity, whereas the leachate from the treated samples has no significant toxicity. Finally, the efficacy of the carbon black waste treated with HNO3 as an absorbent for dye removal was investigated. This treated carbon black waste has high adsorption capacity (∼361.2mg dye/g carbonblack), which can be attributed to its high specific surface area (∼559m2/g). The treated carbon black waste with its high adsorption capacity and lack of cytotoxicity is a promising adsorbent material. Moreover, the carbon black waste was found to show high electrical conductivity (ca. 10S/cm), making it a potentially valuable source of conductive material.

The impact of algal biochar addition on mesophilic and thermophilic anaerobic co-digestion of algal biomass and food waste was investigated with a focus on semi-continuous operations and functional microbial communities. Under batch co-digestion, the highest co-digestion synergy was observed for a mixture of 25% food waste and 75% algal biomass. During semi-continuous co-digestion of 25% food waste-75% algal biomass mixture, biochar amended digesters exhibited a 12–54% increase in average methane yield (275.8–394.6 mL/gVS) compared to the controls. Elevated temperature induced narrow distributions of volatile fatty acids (VFAs) by inhibiting the production of branched VFAs. Genus Proteiniphilum was selectively enriched by 3.2 folds in mesophilic digesters with biochar amendment while genus Defluviitoga was selectively enriched in thermophilic digesters due to elevated temperature. Methanogenic communities were significantly different in mesophilic and thermophilic digesters. Biochar amendment contributed to shifts in the predominant methanogens leading to a more balanced state of two methanogenic pathways.

Gasification waste, also known as carbon soot, is solid industrial waste from the bottom residual of an oil refinery and contains a substantial amount of toxic vanadium. In this work, we report an ...

Dry mouth or xerostomia is a frequent medical condition among the polymedicated elderly population. Systemic pilocarpine is included in the first line of pharmacological therapies for xerostomia. However, the efficacy of existing pilocarpine formulations is limited due to its adverse side effects and multiple daily dosages. To overcome these drawbacks, a localized formulation of pilocarpine targeting the salivary glands (SG) was developed in the current study. The proposed formulation consisted of pilocarpine-loaded Poly(lactic-co-glycolic acid) (PLGA)/poly(ethylene glycol) (PEG) nanofiber mats via an electrospinning technique. The nanofiber mats were fully characterized for their size, mesh porosity, drug encapsulation efficiency, and in vitro drug release. Mat biocompatibility and efficacy was evaluated in the SG organ ex vivo, and the expression of proliferation and pro-apoptotic markers at the cellular level was determined. In vivo short-term studies were performed to evaluate the saliva secretion after acute SG treatment with pilocarpine-loaded nanofiber mats, and after systemic pilocarpine for comparison purposes. The outcomes demonstrated that the pilocarpine-loaded mats were uniformly distributed (diameter: 384 &plusmn, 124 nm) in a highly porous mesh, and possessed a high encapsulation efficiency (~81%). Drug release studies showed an initial pilocarpine release of 26% (4.5 h), followed by a gradual increase (~46%) over 15 d. Pilocarpine-loaded nanofiber mats supported SG growth with negligible cytotoxicity and normal cellular proliferation and homeostasis. Salivary secretion was significantly increased 4.5 h after intradermal SG treatment with drug-loaded nanofibers in vivo. Overall, this study highlights the strengths of PLGA/PEG nanofiber mats for the localized daily delivery of pilocarpine and reveals its potential for future clinical translation in patients with xerostomia.

In this study, solar thermal power coupled with a direct irradiated solar thermochemical reactor using porous-medium NiFe2O4@ZrO2 oxygen exchange material was investigated by combining experiments to the numerical models. The ability of ZrO2, NiFe2O4, and NiFe2O4@ZrO2 to release/uptake O2 and their CO2-splitting characteristics are analyzed by the thermogravimetric analyzer (TGA) and the microstructural changes and chemical composition of NiFe2O4@ZrO2 are examined by scanning electron microscopy (SEM) and x-ray energy dispersive spectrometer (EDS). The experiment performed with a redox thermochemical reactor under a high-flux solar spectrum resulted in a total of 337.89 mL of CO collected during 46 min of CO2-splitting over NiFe2O4@ZrO2 redox material. Higher CO2-splitting activity of NiFe2O4 resulting in 186.545 μmol/g and 130.707 μmol/g of CO yield at 1293-795 °C and 100 sccm of CO2 flow rate were obtained by TGA at the first and second cycle, respectively. The results of both experiments showed significant CO yield at the early stages of oxygen carriers’ re-oxidation with CO2. This study provided important results that could have significant contributions to the solar thermochemical energy storage and CO2 chemical transformation processes.

Thermal chemical processing of plastic has been seen as an efficient practice for the disposal and resource utilization facing the current plastic waste problem. A pyrolysis followed by catalytic decomposition process was investigated in this work to produce carbon materials from polypropylene plastic over FeNi catalysts. The effects of both catalysis temperature (600, 700 and 800 °C) and catalyst type on the gaseous yields, as well as the physicochemical properties (morphology, porosity, purity and graphitization degree) of the as-obtained carbon materials were systematically explored. Various technologies including high resolution electron microscopies, temperature programmed oxidation, Raman, X-ray diffraction were used for full characterizations of the as-obtained carbons. Results show that the yields of both carbon and hydrogen gas were significantly proportional to the catalysis temperature. In terms of the physiochemical properties of carbon materials, the low catalysis temperature of 600 °C generated the majority amorphous and disordered carbons, due to the insufficient decomposition reactions and low catalyst activity. Catalysis temperature higher than 700 °C was necessary for the successful growth of carbon nanotubes, while further increase in temperature mainly acted on the yield rather than thermal stability and graphitic degree. High purity multi-walled carbon nanotubes with outer diameters of 20–30 nm and length up to few micrometers were generated with FeNi1 at 800 °C. FeNi1 catalyst synthesized by sol–gel method displayed higher activity towards the production of high quality carbon materials than FeNi2 catalyst at any temperature range investigated, due to the porous structure and the uniform dispersion of metal particles.