One of the problems of the scalability to industrial applications of pyrolysis reactors is the high electric energy consumption. In this study, a novel device in which a self-sustaining combustion ...front drives the input energy for pyrolysis is proposed. A new methodology to define a representative longitudinal temperature profile based on the time-averaged method at each thermocouple position is introduced. The reactor was tested under operating conditions of air velocities, and bed compositions. The reliability of twenty-nine runs was verified through repeatability, empirical dimensionless correlations, and analysis of variance. The temperature average standard deviation ranged from 30 °C to 54 °C, depending on the bed composition. The dimensionless analysis revealed the power-law relationship between temperature and inputs. The analysis of variance explained the independence of the input parameters on defining the longitudinal temperature profile. A positive energy balance ranging from 1.6 to 5.8 kWh/kg of initial fuel mass, a consequence of a self-sustaining combustion process, was a characteristic of all experiments.
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•The representative temperature profile is based on the time-averaged method.•Temperature profile is a power-law function of bed composition and air velocity.•Self-sustaining combustion process carried enough energy to supply pyrolysis.•The reactor's feasibility is ensured by a positive energy balance.•Sensitivity analysis based on empirical and statistical correlations.
This work investigates for the first time the classical aspects of smoldering front propagation in an annular reactor while presenting new concepts and making new contributions in methodologies of ...establishing the longitudinal temperature profile, calculating the front velocity, and determining the combustion front’s regime. Twenty-nine experiments using different porous beds supported the argument that annular reactor design is, at present, the best for recovering the combustion heat for concomitant processes. Three methods for calculating the front velocity were employed, of which the mass derivative and mass balance methods were specially developed for combustion in heterogeneous beds. The mass balance modeling constrained by the gas analysis results revealed the reactions’ stoichiometry and front velocity relationships with the product formation rate. As a result, the model returned the total oxygen mass, front velocity correction, actual fixed carbon amount oxidized by the front, and the Equivalent Ratio (ER) value, a concept borrowed from gasification studies. It was found that the smoldering front propagated under a gasification regime 0.21 ¡ ER ¡ 0.37. The front structure revealed that the oxidation reaction’s heat was mostly convected downstream of the reaction front resulting in an average bed temperature increase even when the front was close to its propagation’s limit. Finally, the Energy Availability (EA) assessment confirmed that the smoldering front propagation in an annular section is one exceptional design to drive the energy out-of-bed to feed a concomitant process — considering a pyrolysis heat of 1100 kJ/kg for the study.
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•Smoldering front propagation in a reactor with annular cross-section.•New reactor design, Combustion Driven Pyrolysis Reactor, C-DPyR.•Out-of-bed heat recovering for concomitant processes.•High energy availability allows the conversion of energy-intensive materials.•Feasibility of using low-grade fuels to drive heat.
This review aims to explore the potential of resveratrol, a polyphenol stilbene, and beta-lapachone, a naphthoquinone, as well as their derivatives, in the development of new drug candidates for ...cancer. A brief history of these compounds is reviewed along with their potential effects and mechanisms of action and the most recent attempts to improve their bioavailability and potency against different types of cancer.
•New adsorbent materials based on chitosan/alginate and Fe3O4@SiO2 were carried out.•Hydrogel composites acted as adsorbent materials for Pb(II) ions.•Magnetic composites removed Pb(II) ions from ...aqueous systems.•Magnetic composite guaranteed Pb(II) removal of a battery effluent.•Magnetic composite removed the turbidity of a battery effluent.
Chitosan/alginate (CHT/ALG) and magnetic CHT/ALG/Fe3O4@SiO2 composites were successfully prepared and used as adsorbent materials to remove Pb(II) from aqueous systems. New hydrogel beads were yielded through an unpublished methodology, examining the ionic strength of the chitosan (CHT) solutions. Polyvalent cations and toxic cross-linking agents such as glutaraldehyde and epichlorohydrin, frequently used to prepare CHT/ALG-based materials were not used in this study. The samples were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy, thermal analysis (TAG/DSC), and zeta potential measurements. The addition of Fe3O4@SiO2 (8 ± 3 nm) significantly modified the surface morphology of the composites. The CHT/ALG/Fe3O4@SiO2(8) hydrogel comprising the highest Fe3O4@SiO2 content (8.0 wt%), displayed magnetic feature and zeta potential of −76.8 mV at pH 6.0. Kinetic and equilibrium adsorption studies reveal that Elovich and Redlich-Peterson mathematical models provide the best fits for the experimental data, respectively. The magnetic composite CHT/ALG/Fe3O4@SiO2(8) had maximum adsorption capacity (qm) of 234.77 mg g−1 and adsorption/desorption cycles designed its reuse performance. The CHT/ALG/Fe3O4@SiO2(8) hydrogel was applied to treat battery effluent, achieving 99.04% Pb(II) removal, and diminishing the turbidity from 73 to 3.0 NTU. Wastewater and battery effluents contaminated with Pb(II) may be treated using an eco-friendly magnetic hybrid material based on CHT/ALG/Fe3O4@SiO2 as the adsorbent.
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•N–S-doped mesoporous carbon has been synthesized from a new template and heteroatoms precursor.•The material has high mesopore volume (0.450cm3g−1).•N–S-doped carbon is composed for ...1.63% of nitrogen and 2.29% of sulfur.•The IBF adsorption performance and involved mechanism have been studied.•N–S-doped carbon presents maximum monolayer adsorption capacity of 56.78mgg−1 at 30°C.
We report the synthesis of N–S-doped mesoporous carbon (NSMC) using bone char (BC) as template and heteroatoms precursor. The efficiency of process was evaluated through the synthesis of a material without the use of BC (SC). The materials were properly characterized and textural analysis showed that the BC led to increase of surface area and mesoporous volume for NSMC (568m2g−1 and 0.294cm3g−1) as compared to SC (518m2g−1 and 0.130cm3g−1). The doping of NSMC’s lattice was evaluated from XPS survey spectra. The spectra deconvolution showed that sulfur was incorporated as thiophene and oxidized sulfur, while nitrogen was incorporated as pyridinic, pyrrolic and graphitic, with relative composition of 2.29% and 1.63%, respectively. The Raman and X-ray diffraction analyses showed that the use of BC led to decrease in the intensity of graphitic-band, indicating the doping of carbon lattice. The pHpzc analysis showed that NSMC’s surface has acidic character with pH 3.50, which favored the ibuprofen (IBF) adsorption at pH 4.0, once at this pH value, approximately 87% of IBF species are in protonated form, according to the distribution diagram of species. Adsorption kinetic studies indicated the pseudo-second order model as the best to describe the experimental data. Moreover, adsorption equilibrium studies revealed that the Langmuir model allowed the determination of NSMC’s adsorption capacity (56.78mgg−1); while thermodynamic study showed that the adsorption is a spontaneous and exothermic process. From the results obtained adsorption mechanism of IBF onto the NSMC was proposed.
•The genome of two member of a bacterial community able to degrade chloroaromatic compounds were sequence.•MT1 strain is the only bacterial member of the community possessing genes for the ...degradation of chloroarosalicylates.•MT3 strain is capable of metabolizing chlorocatechol and chloromuconate but not proteoanemonin.•MT3 strain has the capacity to mineralize nitroaromatic compounds and phenols.
We describe the genome sequence of Pseudomonas reinekei MT1 and Achromobacter xylosoxidans MT3, the most abundant members of a bacterial community capable of degrading chloroaromatic compounds. The MT1 genome contains open reading frames encoding enzymes responsible for the catabolism of chlorosalicylate, methylsalicylate, chlorophenols, phenol, benzoate, p-coumarate, phenylalanine, and phenylacetate. On the other hand, the MT3 strain genome possesses no ORFs to metabolize chlorosalicylates; instead the bacterium is capable of metabolizing nitro-phenolic and phenolic compounds, which can be used as the only carbon and energy source by MT3. We also confirmed that MT3 displays the genetic machinery for the metabolism of chlorocathecols and chloromuconates, where the latter are toxic compounds secreted by MT1 when degrading chlorosalicylates. Altogether, this work will advance our fundamental understanding of bacterial interactions.
Great efforts have been made over the years to assess the effectiveness of air pollution controls in place in the metropolitan area of São Paulo (MASP), Brazil. In this work, the community multiscale ...air quality (CMAQ) model was used to evaluate the efficacy of emission control strategies in MASP, considering the spatial and temporal variability of fine particle concentration. Seven different emission scenarios were modeled to assess the relationship between the emission of precursors and ambient aerosol concentration, including a baseline emission inventory, and six sensitivity scenarios with emission reductions in relation to the baseline inventory: a 50% reduction in SO
2
emissions; no SO
2
emissions; a 50% reduction in SO
2
, NO
x
, and NH
3
emissions; no sulfate (PSO
4
) particle emissions; no PSO
4
and nitrate (PNO
3
) particle emissions; and no PNO
3
emissions. Results show that ambient PM
2.5
behavior is not linearly dependent on the emission of precursors. Variation levels in PM
2.5
concentrations did not correspond to the reduction ratios applied to precursor emissions, mainly due to the contribution of organic and elemental carbon, and other secondary organic aerosol species. Reductions in SO
2
emissions are less likely to be effective at reducing PM
2.5
concentrations at the expected rate in many locations of the MASP. The largest reduction in ambient PM
2.5
was obtained with the scenario that considered a reduction in 50% of SO
2
, NO
x
, and NH
3
emissions (1 to 2 μg/m
3
on average). It highlights the importance of considering the role of secondary organic aerosols and black carbon in the design of effective policies for ambient PM
2.5
concentration control.
The application of best management practices is a long-term conservation effort in Midwest U.S. croplands, and many farmers have adopted structural conservation practices (SCPs) to reduce soil ...erosion and surface water runoff, such as terraces and grassed waterways. Despite that, the geographic distribution of these practices is barely known in the region, and mapping initiatives are required to develop timely and spatially explicit inventories of SCP areas. This study presents the first mapping of SCPs in the agricultural areas over 12 Midwest U.S. states. Semantic segmentation model (adapted U-Net) and National Agriculture Imagery Program 2018–2019 data were used to map the SCP areas at 2-m spatial resolution (490.2 billion pixels). In general, mapping results achieved 78.2% overall accuracy across 20 counties. Our results indicate that 52% of SCP areas are distributed over Iowa (26%), Illinois (15%), and Nebraska (11%). In contrast, the states with the lowest SCP areas are Michigan and North Dakota, with less than 4% of SCP areas. Since the SCP extent is also dependent on the number of cropland areas per state, the percentage of SCP per cropland area was calculated. Specifically, the average percentage of SCP area per cropland is ~1.19%, ranging from 0.8 (e.g., North Dakota and south Minnesota) to 5.5% (e.g., northeast Kansas and southwest Iowa). Interestingly, results also illustrate that regions with high soil erosion rates present the largest percentage of SCP areas in croplands, indicating conservation efforts by farmers. While this preliminary analysis shows some limitations in the mapping quality (mislabel, non-accurate location or discontinuity of SCP areas), the framework has a potential for operational conservation monitoring. The development of such mapping has positive implications for conservation programs, and this geospatial inventory is easily accessible information for the large-area evaluation of conservation practices across Midwest U.S. croplands.
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•First mapping of structural conservation practices (SCP) using deep learning model•The spatial distribution of SCP areas is highly distinct among U.S. states.•Iowa, Nebraska and Kansas presented the largest area of SCPs in agricultural fields.•Regions with high soil erosion rates present the largest percentage of SCP areas.•Further research is needed to improve SCP mapping for field-scale assessment.
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