Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 58.352
Filtrar
1.
Sci Total Environ ; 803: 149964, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34481162

RESUMEN

Energy conversion and utilization of sewage sludge (SS) and lignocellulosic biomass are an important measure to deal with environmental pollution and resource utilization. Addressing the waste by-product in a clean way is essential. In this study, solid char fuel (hydrochar) was obtained through co-hydrothermal carbonization of SS with pinewood sawdust (PS), and methane gas was obtained through anaerobic digestion (AD) of hydrothermal carbonization wastewater (HTCWW). The energy conversion performance of the feedstock organics under different HTC conditions (temperature of 160 °C, 220 °C, and 280 °C; reaction time of 0, 2, and 4 h; feedstock liquid-solid mass ratio of 4:1, 10:1, and 16:1), and the mass and energy yields of hydrochar and methane and their influencing factors were emphasized. More than 60% of the energy in SS and PS can be recovered by coupling the HTC-AD process. With the increase in hydrothermal reaction temperature and reaction time, the mass yield of hydrochar decreased, but the higher heating value increased. The maximum energy yield of hydrochar was 86.47% under the HTC temperature of 160 °C, liquid-solid ratio of 10:1, and reaction time of 2 h. The HTCWW obtained at a lower temperature (160 °C) showed the highest cumulative methane yield of 304.16 mL-CH4/g-COD.


Asunto(s)
Pinus , Aguas del Alcantarillado , Anaerobiosis , Carbono , Temperatura , Aguas Residuales
2.
Sci Total Environ ; 803: 149993, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34482145

RESUMEN

The ecological conservation and high-quality development of China's Yellow River Basin is a national strategy proposed in 2019. Under China's goal of achieving a carbon peak by 2030 and carbon neutrality by 2060, clarifying the carbon footprint of each province and the transfer paths of embodied carbon emissions is crucial to the carbon reduction strategy for this region. This paper uses input-output model and multi-regional input-output model to account for the carbon footprint of nine provinces in the Yellow River Basin, and to estimate the amount of embodied carbon transfer between provinces and industrial sectors. Social network analysis is applied to identify the critical industries in the inter-provincial embodied carbon emission transfers from the three major industries. We found that the per capita carbon footprint of the Yellow River Basin decreased by 23.4% in 2017 compared to 2012. Among the sectoral composition of the carbon footprint of each province, "Processing and manufacturing of petroleum, coking, nuclear fuel, and chemical products", "Construction", "Other services", and "Metal processing and metal, non-metallic products" are the four sectors with a higher proportion of emissions. The embodied carbon emission transfer between the provinces in middle and lower reaches of the Yellow River Basin is much higher than that between the upstream provinces. Among carbon emission transfer network of three major industries in nine provinces,the secondary industry in Shaanxi has the highest centrality and is the most critical industry. This study provides a theoretical basis and data support for formulating carbon emission reduction plans in the Yellow River Basin.


Asunto(s)
Carbono , Ríos , Carbono/análisis , Dióxido de Carbono/análisis , Huella de Carbono , China , Industrias
3.
J Colloid Interface Sci ; 607(Pt 1): 111-124, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34492348

RESUMEN

Herein, a novel adsorbent based on carbon-modified zirconia/spinel ferrite (C@ ZrO2/Mn0.5Mg0.25Zn0.25Fe2O4) nanostructures were chemically prepared to remove 60Co and 152+154Eu radionuclides from liquid media using batch experiments. The XRD pattern confirms the successful preparation of the C@ZrO2/MnMgZnFe2O4 composite. Also, SEM and TEM images confirmed that the composite owns a heterogeneous morphology in the nanoscale range. The optical band gap value of Mn0.5Mg0.25Zn0.25Fe2O4, ZrO2, and the composite samples was 1.45, 2.38, and 1.54 eV, respectively. Many parameters have been studied as the effect of time, solution pH, and initial ion concentration. The kinetics models for the removal process of 152+154Eu and 60Co radionuclides were studied. The second-order kinetic equation could describe the sorption kinetics for both radionuclides. The Langmuir monolayer capacity for 60Co was 82.51 mg/g and for 152+154Eu was 136.98 mg/g. The thermodynamic parameters such as free energy ΔGo, the enthalpy ΔHo, and the entropy ΔSo were calculated. The results indicated that the sorption process has endothermic nature for both two radionuclides onto C@ZrO2/MnMgZnFe2O4 composite.


Asunto(s)
Nanoestructuras , Contaminantes Químicos del Agua , Adsorción , Óxido de Aluminio , Carbono , Cobalto , Europio , Compuestos Férricos , Concentración de Iones de Hidrógeno , Cinética , Óxido de Magnesio , Soluciones , Temperatura , Termodinámica , Contaminantes Químicos del Agua/análisis , Circonio
4.
J Colloid Interface Sci ; 607(Pt 1): 16-23, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34492349

RESUMEN

The exploration of carbon dots (CDs) with high quantum yield, facile synthesis path and satisfying output for their multiple applications remains a challenge. Thus, a silicon-doped orange-emitting carbon dots (O-CDs) is synthesized via a one-step hydrothermal method o-phenylenediamine and ethyl orthosilicate as raw materials. The O-CDs exhibits a bright and non-excitation-dependent emission peaking at 580 nm, and the corresponding quantum yield could be greatly boosted from 39.2 % to 64.1 % by silicon doping. The obtained O-CDs possess good biocompatibility and promising luminescence stability with varying solvents, ionic concentrations and temperatures. Its bio-imaging ability is performed by incubating zebrafish embryos with O-CDs aqueous solution, and clear in-vivo fluorescent images are obtained. Furthermore, due to its high-efficient and specific pH-sensitive emission with excellent dispersibility, the O-CDs can be used as a fluorescent ink for dual-model data encry/decryption in both hand-writing and stamp printing. Therefore, the as-prepared O-CDs show the potential as promising candidate for biomedical diagnosis, data encryption, and anti-counterfeiting.


Asunto(s)
Citrus sinensis , Puntos Cuánticos , Animales , Carbono , Colorantes Fluorescentes , Concentración de Iones de Hidrógeno , Luminiscencia , Silicio , Pez Cebra
5.
Sci Total Environ ; 803: 150033, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34492486

RESUMEN

In this study, a novel biodegradable PHBV/PLA/rice hulls (PPRH) composite was applied and tested as biofilm attachment carrier and carbon source in two bioreactors for biological denitrification process. The denitrification performance, effect of operational conditions and microbial community structure of PPRH biofilm were evaluated. The batch experiment results showed that PPRH-packed bioreactor could completely remove 50 mg L-1 of NO3--N at natural pH (ca. 7.5) and room temperature. The continuous flow experiments indicated that high NO3--N removal efficiency (77%-99%) was achieved with low nitrite (<0.48 mg L-1) and ammonia (<0.81 mg L-1) accumulation, when influent NO3--N concentration was 30 mg L-1 and hydraulic retention time was 2-6 h. Furthermore, the microbial community analysis indicated that bacteria belonging to genus Diaphorobacter in phylum Proteobacteria were the most dominant and major denitrifiers in denitrification. In summary, PPRH composite was a promising carbon source for biological nitrate removal from water and wastewater.


Asunto(s)
Comamonadaceae , Microbiota , Oryza , Reactores Biológicos , Carbono , Desnitrificación , Nitratos/análisis , Nitrógeno , Poliésteres , Aguas Residuales
6.
Sci Total Environ ; 803: 149874, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34492491

RESUMEN

The treatment of sewage sludge (SS) is an environmental problem worldwide. In recent years, hydrothermal carbonization (HTC) of SS for hydrochar (HC) has attracted extensive attention. This study preliminarily explored the microwave-assisted HTC of SS for the first time. Increasing the reaction temperature (150-250 °C) and reaction time (0-120 min) resulted in a decrease in the HC yield, and it gradually increased with the rising solid-liquid ratio (0.03-0.25 g/mL). Compared with raw SS, the HC products possessed higher aromaticity, carbonization degree, porosity, and polarity, and lower content of soluble nutrients (N/P/K) and leachable heavy metals (Cu, Zn, Pb, Cd, Cr, and Ni), indicating a lower risk of nutrient and heavy metal loss. Attention should be paid to the total contents of Zn and Cd in HC exceeded the permitted value for use in cultivated land with edible crops. The use of CaO as a catalyst improved the yield of HC, made the HC and process water (PW) weakly alkaline, and further passivated the heavy metals in the HC. In the case of H3PO4, although the conversion of SS was enhanced (lower content of volatile organic matter in HC), the contents of soluble nutrients (N/P/K) in HC/PW increased, and the migration of Zn and Cd into process water was enhanced. The HCs obtained in this study had poor combustion properties, but higher ignition temperatures than raw SS. PW must be properly treated or recycled because it still contained high contents of organic matter and nutrients. This fundamental study provides basic insights into the microwave-assisted HTC of SS.


Asunto(s)
Metales Pesados , Aguas del Alcantarillado , Carbono , Microondas , Temperatura , Agua
7.
Sci Total Environ ; 803: 150057, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34500269

RESUMEN

Black carbon (BC), characterized by high aromaticity and stability, has been recognized as a substantial fraction of the carbon pool in soil and sediment. The effect of BC on the particulate organic carbon (POC) pool in lake water, which is an important medium of carbon transmission and transformation, has not been thoroughly studied. The investigations of BC composition and distribution, POC, polycyclic aromatic hydrocarbons (PAHs), and stable carbon and nitrogen isotopes were conducted in a eutrophic urban lake, Taihu Lake, which is the third largest freshwater lake in China. The results indicate that the BC is composed of 55 ± 12% char and 45 ± 12% soot and accounted for 12 ± 6% of POC (the maximum value is 31%). The comparatively high levels of BC and char are distributed in the northern Taihu Lake, especially in Meiliang Bay (0.72 ± 0.38 mg L-1 and 0.45 ± 0.24 mg L-1). The distribution of soot presents a declining trend from the lakeshore to the central lake, particularly in the northern, western, and southern lakes. Source apportionment results from positive matrix factorization of PAHs suggest that consumption of fossil fuel (79 ± 20%) is the dominant source of BC, which agrees with the low ratio of char/soot (1.41 ± 0.71) and relatively depleted δ13C. The covariation of BC and PAHs and terrestrial dissolved organic carbon indicate that the effect of terrestrial input significantly regulates the distribution of BC in Taihu Lake, which is reflected in the high BC value along the lakeshore.


Asunto(s)
Lagos , Hidrocarburos Policíclicos Aromáticos , Carbono/análisis , China , Monitoreo del Ambiente , Sedimentos Geológicos , Hidrocarburos Policíclicos Aromáticos/análisis , Hollín/análisis
8.
Sci Total Environ ; 803: 150035, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34500275

RESUMEN

The Loess Plateau is China's primary apple-growing area, and the orchard is a significant source of greenhouse gases (GHGs) emissions due to high nitrogen fertilizer input. Thus, a two-year field study was carried out to investigate the effects of apple wood derived biochar on GHGs emissions during apple orchard production, including soil organic carbon sequestration (SOCSR) and net global warming potential (NGWP) assessments. There are four treatments in this study: 20 t ha-1 biochar in a non-fertilized plot (B); no biochar in a fertilized plot (F); 20 t ha-1 biochar in a fertilized plot (FB); no biochar in a non-fertilized plot (CK). Results showed that the combined application of biochar and fertilizer stimulated CO2 emissions by 9.25% and 8.39% than either biochar or fertilizer alone. Meanwhile, biochar in fertilized plot increased annual N2O emissions by 32.6% as compared to fertilized plot without biochar amendment. Compared with CK, biochar had no significant effect on GHG emissions in unfertilized plot. The N2O emission factor of FB and F were 0.91% and 0.45% respectively in 2017-2018 and they were both 0.34% in 2018-2019. Moreover, compared with CK, the FB and B treatments increased the SOCSR by 316.52% and 354.78%, while, decreased the NGWP by 368.93% and 480.91%, respectively. Thus, biochar application may help reduce the impact of apple production on climate change by sequestering more soil organic carbon and decreasing the NGWP.


Asunto(s)
Malus , Suelo , Agricultura , Carbono , Dióxido de Carbono/análisis , Secuestro de Carbono , Carbón Orgánico , China , Calentamiento Global , Metano/análisis , Óxido Nitroso/análisis
9.
J Colloid Interface Sci ; 607(Pt 1): 1-15, 2022 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-34500412

RESUMEN

The intracellular O2-supply not only can relieve tumor hypoxia but also enhance the effects of photodynamic therapy (PDT). In this work, metallic Mo2C@N-carbon@PEG nanoparticles were constructed to reveal the near infrared (NIR)-photocatalytic O2 generation and promote photodynamic therapy (PDT). Here, (NH4)6Mo7O24·4H2O nanorods and urea were adopted as resources that were calcined to obtain Mo2C@N-carbon nanoparticles (20 nm). All samples displayed high NIR absorption as well as photothermal conversion efficiency of up to 52.7 % (Mo2C@N-Carbon-3@PEG). The density functional theory calculations demonstrated the metallic characteristic of Mo2C and that the consecutive interband/intraband charge-transition was responsible for the high NIR harvest and redox ability of electron-hole pairs, making the NIR-photocatalytic O2 and reactive oxygen species (ROS) generation. In comparison with the pure Mo2C, the heterostructure displayed twice the performance due to the enhanced charge-segregation between Mo2C and N-carbon. Given the high X-ray absorption coefficient and photothermal ability, the nanocomposite could be used in novel computer tomography and photothermal imaging contrast. Furthermore, the novel biodegradation and metabolism behaviors of nanocomposites were investigated, which were reflected as elimination from the body (mouse) via feces and urine within 14 days. The as-synthesized Mo2C@N-Carbon@PEG nanocomposites integrated the dual-model imaging, intracellular O2-supply, and phototherapy into one nanoplatform, revealing its potential for anti-cancer therapy.


Asunto(s)
Nanopartículas , Neoplasias , Fotoquimioterapia , Animales , Carbono , Línea Celular Tumoral , Ratones , Molibdeno , Neoplasias/tratamiento farmacológico , Oxígeno , Fototerapia
10.
Sci Total Environ ; 803: 150030, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525688

RESUMEN

Biological soil crusts (BSCs), known as ecological engineers, play an important role in soil organic carbon (SOC) sequestration in dryland ecosystems. Although numerous individual studies had been conducted, the global patterns of the changes in SOC concentration following BSCs establishment remain unclear. In this study, we performed a comprehensive meta-analysis of 184 independent observations at 47 sites to quantify the responses of SOC and other soil variables to BSCs establishment and identify the underlying mechanisms. Our results showed that BSCs generally increased SOC by 70.9% compared to the controls (uncrusted soil), and the positive effects of BSCs on SOC in deserts (120.3%) were stronger than those in grasslands (32.7%). Mosses and lichens had a stronger positive effect on SOC than algae crusts (67.5%, 82.8%, and 58.2% respectively). Mixed crusts accumulated more SOC (181.6%) than single (moss, lichen and algae) crusts. The presence of BSCs considerably increased total nitrogen (TN) (+80.7%), total phosphorus (TP) (+20.3%), available N (+62.7%), and available P (+14.3%). Significant relationships were observed among the effect size of SOC and climate and soil N and P in both desert and grassland. The random forest analysis showed that TN could be considered as a determinant of the concentration of SOC, followed by climate (P < 0.01). Our study shows that the capacity of the BSCs to fix and store C could be regulated by soil N and P dynamics, indicating a major finding opening new ways to promote soil recovery and formation. Our findings highlight the remarkable contribution of mixed crusts to soil C pools; this contribution needs to be incorporated into regional and global models to predict the effects of human disturbance on drylands worldwide and for assessing the soil C budget.


Asunto(s)
Cianobacterias , Suelo , Carbono , Secuestro de Carbono , China , Clima Desértico , Ecosistema , Humanos , Nitrógeno , Microbiología del Suelo
11.
Sci Total Environ ; 803: 150044, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525696

RESUMEN

A typhoon is extreme weather that flushes terrestrial carbon (C) loads and temporally mixes the entire water columns of lakes in subtropical regions. A C flux varies based on the trophic level associated with the ecological cycle related to hydraulic retention time (residence time). Herein, we sought to clarify how the hydraulic retention time and the disturbance from a typhoon affect the C flux regimes in two subtropical mountain lakes in a humid region of Taiwan with different trophic levels-oligotrophic and mesotrophic. We investigated the meteorological data and vertical profiles of the water temperature, dissolved inorganic carbon (DIC), dissolved organic C (DOC), and chlorophyll a (Chl. a) during the pre-typhoon period (April-July), during the typhoon period (August-November), and the post-typhoon period (December-March) for five years (2009-2010 and 2015-2017). We applied a three-dimensional environmental model (Fantom) to investigate the hydraulic retention effect on the net ecosystem production (NEP) using the residence time in stratified lakes. The results demonstrate that typhoon-induced mixing associated with the hydraulic retention effect plays one of the critical roles in controlling the NEP and C flux in shallow subtropical lakes.


Asunto(s)
Tormentas Ciclónicas , Lagos , Carbono , Ciclo del Carbono , Clorofila A , Ecosistema
12.
Sci Total Environ ; 803: 150064, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525700

RESUMEN

Chloroacetamides are commonly used in herbicide formulations, and their occurrence has been reported in soils and groundwater. However, how their chemical structures affect transformation kinetics and pathways in the presence of environmental reagents such as hydrogen sulfide species and black carbon has not been investigated. In this work, we assessed the impact of increasing Cl substituents on reaction kinetics and pathways of six chloroacetamides. The contribution of individual pathways (reductive dechlorination vs. nucleophilic substitution) to the overall decay of selected chloroacetamides was differentiated using various experimental setups; both the transformation rates and product distributions were characterized. Our results suggest that the number of Cl substituents affected reaction pathways and kinetics: trichloroacetamides predominantly underwent reductive dechlorination whereas mono- and dichloroacetamides transformed via nucleophilic substitution. Furthermore, we synthesized eight dichloroacetamide analogs (Cl2CHC(=O)NRR') with differing R groups and characterized their transformation kinetics. Dynamic NMR spectroscopy was employed to quantify the rotational energy barriers of dichloroacetamides. Our results suggest that adsorption of dichloroacetamides on black carbon constrained R groups from approaching the dichloromethyl carbon and subsequently favored nucleophilic attack. This study provides new insights to better predict the fate of chloroacetamides in subsurface environments by linking their structural characteristics to transformation kinetics and pathways.


Asunto(s)
Carbono , Sulfuros , Acetamidas , Cinética , Espectroscopía de Resonancia Magnética , Oxidación-Reducción
13.
Sci Total Environ ; 803: 150061, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525705

RESUMEN

Downed woody material (DWM) is a unique part of the forest carbon cycle serving as a pool between living biomass and subsequent atmospheric emission or transference to other forest pools. Thus, DWM is an individually defined pool in national greenhouse gas inventories. The diversity of DWM carbon drivers (e.g., decay, tree mortality, or wildfire) and associated high spatial variability make this a difficult-to-predict component of forest ecosystems. Using the now fully established nationwide inventory of DWM across the United States (US), we developed models, which substantially improved predictions of stand-level DWM carbon density relative to the current national-reporting model ('previous' model, here). The previous model was developed from published DWM carbon densities prior to the NFI DWM inventory. Those predictions were tested using NFI DWM carbon densities resulting in a poor fit to the data (coefficient of determination, or R2 = 0.03). We present new random forest (RF) and stochastic gradient boosted (SGB) regression models to prediction DWM carbon density on all NFI plots and spatially on all forest land pixels. We evaluated various biotic and abiotic regression predictors, and the most important were standing dead trees, long-term annual precipitation, and long-term maximum summer temperature. A RF model scored best for expanding predictions to NFI plots (R2 = 0.31), while an SGB model was identified for DWM carbon predictions based on purely spatial data (i.e., NFI-plot-independent, with R2 = 0.23). The new RF model predicts conterminous US DWM carbon stocks to be 15% lower than the previous model and 2% higher than NFI data expanded according to inventory design-based inference. The new NFI data-driven models not only improve the predictions of DWM carbon density on all plots, they also provide flexibility in extending these predictions beyond the NFI to make spatially explicit and spatially continuous estimates of DWM carbon on all forest land in the US.


Asunto(s)
Carbono , Ecosistema , Biomasa , Carbono/análisis , Ciclo del Carbono , Estados Unidos , Madera/química
14.
Sci Total Environ ; 803: 150012, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525708

RESUMEN

Thermal desorption coupled with different detectors is an important analysis method for ambient carbonaceous aerosols. However, it is unclear how the compounds coexisting in both the gas and particle phases affect carbonaceous aerosol concentrations and measurements during thermal desorption. We observed matrix effects leading to a redistribution of different OC fractions (OC1 to OC4) during the thermal desorption process. These factors led to the formation of OC with low volatility (OC4), mainly from high-volatility OC (OC1 and OC2). Laboratory studies further indicated that ammonium promotes such matrix effects by transforming OC in the particle phase. Therefore, in addition to providing insights into the chemical evolution of OC during haze events, we argue that thermal-desorption-based OC measurements should be used with caution, which is an important step towards a more accurate measurement of OC in the ambient atmosphere.


Asunto(s)
Contaminantes Atmosféricos , Compuestos de Amonio , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Carbono/análisis , Monitoreo del Ambiente , Tamaño de la Partícula , Material Particulado/análisis , Estaciones del Año
15.
Sci Total Environ ; 803: 150135, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525728

RESUMEN

Carbonation treatment (CT) by alkaline fly ash (FA) affects the stability of potentially toxic elements (PTEs). This study investigated the leachability and environmental risk of six PTEs contained in FA during natural and accelerated carbonation (NC, AC) using two typical leaching scenarios with distilled water (DW) and acetic acid (AA). The leaching of Pb/Cu/Cr/Ni in solidified/stabilized FA decreased due to CT in DW leaching, but the leaching of Pb/Zn/Cu/Cd increased due to CT in AA leaching. The leaching of the six PTEs (especially Pb/Cd) in AA leaching was significantly higher than that in DW leaching. CT was a promoting factor to increase the environmental risk level of PTEs in FA leachate, especially in AA leaching with H+ input. In the early stage of NC, under DW leaching tests, the environmental risk level of PTEs in FA leachate can be weakened due to the formation of carbonate minerals in the FA matrix. However, excessive NC increases the environmental risk of leached PTEs due to the decalcification of carbonate minerals. Both NC and AC increased the potential environmental risk of PTEs contained in the carbonated FA matrix. The nucleation and dissolution of carbonate minerals were interdependent with the immobilization and leaching of PTEs, which played a dominant role in the CT and leaching tests respectively. They jointly affected the occurrence behavior of PTEs in the FA matrix in CT tests and the leachability of PTEs in leaching tests. This study demonstrates that it is more scientific to evaluate the leachability of PTEs in carbonated FA according to the actual disposal scenarios.


Asunto(s)
Metales Pesados , Eliminación de Residuos , Carbono , Carbonatos , Ceniza del Carbón , Incineración , Metales Pesados/análisis , Material Particulado , Residuos Sólidos/análisis
16.
Sci Total Environ ; 803: 150104, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525736

RESUMEN

China has pledged to achieve peak carbon emissions by 2030 and to be carbon neutral by the mid-century, and buildings will be the "last mile" sector in the transition to carbon neutrality. To help buildings hit the carbon peak goal, we investigate the different emission scales of carbon emission changes of residential and commercial building operations across 30 provinces in China through the carbon Kuznets curve (CKC) model. We observe that (1) more than three-quarters of the samples can be fitted by the CKC model. Most CKCs are the inverted U-shaped, residential and commercial buildings occupying 93% and 90% at the total emission scale, respectively. In addition, the remains can be illustrated as N-shaped curves. (2) Under the premise of CKCs existence, approximately half of the provincial residential and commercial buildings peak at different emission scales, except for emission per floor space (residential: 89%; commercial: 81%). Provinces with better economic development have a higher peaking probability. In the total emissions, the peaking probability in residential buildings is 33% and 50% for provinces with economic indicators <20,000 Chinese Yuan and 30,000-40,000 Chinese Yuan, respectively, and 22% and 67% for commercial buildings, respectively. (3) Taking carbon intensity as a case study, decoupling analysis examines the robustness of the CKC estimation. Overall, we close the gap of the CKC estimation in commercial and residential buildings, and the proposed methods can be treated as a tool for other economies to illustrate the retrospective and prospective trajectories of carbon emissions in building operations.


Asunto(s)
Dióxido de Carbono , Carbono , Carbono/análisis , Dióxido de Carbono/análisis , China , Desarrollo Económico , Estudios Prospectivos , Estudios Retrospectivos
17.
Sci Total Environ ; 803: 149767, 2022 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-34525748

RESUMEN

Isotope fractionation between the gas and aerosol phases is an important phenomenon for studying atmospheric processes. Here, for the first time, seasonally resolved stable carbon isotope ratio (δ13C) values are systematically used to study phase interactions in bulk aerosol and gaseous carbonaceous samples. Seasonal variations in the δ13C of total carbon (TC; δ13CTC) and water-soluble organic carbon (WSOC; δ13CWSOC) in fine aerosol particles (PM2.5) as well as in the total carbon of part of the gas phase (TCgas; δ13CTCgas) were studied at a suburban site in Prague, Czech Republic, Central Europe. Year-round samples were collected for the main and backup filters from 14 April 2016 to 1 May 2017 every 6 days with a 48 h sampling period (n = 66). During all seasons, the highest 13C enrichment was found in WSOC, followed by particulate TC, whereas the highest 13C depletion was found in gaseous TC. We observed a clear seasonal pattern for all δ13C, with the highest values in winter (avg. δ13CTC = -25.5 ± 0.8‰, δ13CWSOC = -25.0 ± 0.7‰, δ13CTCgas = -27.7 ± 0.5‰) and the lowest values in summer (avg. δ13CTC = -27.2 ± 0.5‰, δ13CWSOC = -26.4 ± 0.3‰, δ13CTCgas = -28.9 ± 0.3‰). This study supports the existence of different aerosol sources at the site during the year. Despite the different seasonal compositions of carbonaceous aerosols, the isotope difference (Δδ13C) between δ13CTC (aerosol) and δ13CTCgas (gas phase) was similar during the seasons (year avg. 1.97 ± 0.50‰). Moreover, Δδ13C between WSOC and TC in PM2.5 showed a difference between spring and winter, but in general, these values were also similar year-round (year avg. 0.71 ± 0.37‰). During the entire period, TCgas and WSOC were the most 13C-depleted and most 13C-enriched fractions, respectively, and although the resulting difference Δ(δ13CWSOC - Î´13CTCgas) was significant, it was almost invariant throughout the year (2.67 ± 0.44‰). The present study suggests that the stable carbon isotopic fractionation between the bulk aerosol and gas phases is probably not entirely dependent on the chemical composition of individual carbonaceous compounds from different sources.


Asunto(s)
Contaminantes Atmosféricos , Carbono , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Carbono/análisis , Isótopos de Carbono/análisis , Monitoreo del Ambiente , Material Particulado/análisis , Estaciones del Año
18.
Food Chem ; 370: 131005, 2022 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-34536786

RESUMEN

Opuntia ficus indica (OFI) waste was evaluated as a fermentation feedstock for lactic acid production using Lactobacillus plantarum. Dilute acid pretreatment of the OFI cladodes (OFIC) was performed for extracting maximum fermentable sugars by optimizing process parameters using statistical optimization method. The best results were obtained with HCl 1% (v/v), temperature 120 °C, residence time 40 min, granulation 350 µm and substrate loading 5% (w/v), the sugar concentration reached 24 g/L with low concentration of hydroxymethylfurfural. The feasibility of producing lactic acid from OFI fruit peel (OFIFP) as a source of carbon was also investigated. Lactobacillus plantarum was shown to have a capacity for lactic acid production from OFIC350 (granulation 350 µm) hydrolysate and OFIFP extract without detoxification. The highest lactic acid yields of 0.46 and 0.78 g/g were obtained from enzymatic hydrolysate of pretreated OFIC350 and OFIFP extract, respectively.


Asunto(s)
Lactobacillus plantarum , Opuntia , Carbono , Análisis Costo-Beneficio , Fermentación , Ácido Láctico
19.
Chemosphere ; 286(Pt 2): 131760, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34352536

RESUMEN

Heavy metal ions (HMI) have attracted worldwide concern due to their serious environmental pollution which led to the risk of health conditions. From Red Malus floribunda fruits, nitrogen-doped carbon dots (N-CDs) were prepared, followed by hybrid-spherical shaped hydrogel particles (CGCDs) were prepared. The prepared CGCDs were utilized as adsorbents for HMI-(Hg(II), Cd(II), Pb(II), and Cr(III)) from water. N-CDs with about 4.0 nm in diameter were characterized by various techniques such as field emission-scanning electron microscopy (FE-SEM) and attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR) that confirm the presence of nitrogen, oxygen, and carbon functionalities. The prepared spherical CGCDs were characterized very well before it was used as HMI adsorbents. The sizes of the CGCDs were ranges between 20 and 300 µm and the degree of swelling was calculated as 1320 %. ATR-FTIR and X-ray diffraction analyses reveal the presence of N-CDs in CGCDs. Further, FE-SEM confirms the spherical shape morphology of CGCDs. Three different concentrations of HMI solutions were 500 mg/L, 1000 mg/L, and 1500 mg/L. Hg(II) adsorbed proficiently by CGCDs in single metal ion systems with ~72 % and almost complete removal of Hg(II) ions (99 %) in multiple metal ion systems was observed. Moreover, all metal ions Hg(II), Cd(II), Pb(II), and Cr(III) were efficiently (>70 %) removed in multiple systems by CGCDs. After HMI adsorption experiments, the elemental mapping from FE-SEM and X-ray photoelectron spectroscopy studies conveys the presence of HMI on CGCDs. This suggests that CGCDs would be a suitable adsorbent for the simultaneous removal of multiple HMI from wastewater.


Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , Adsorción , Carbono , Hidrogeles , Iones , Metales Pesados/análisis , Aguas Residuales , Contaminantes Químicos del Agua/análisis
20.
Chemosphere ; 286(Pt 2): 131763, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34352552

RESUMEN

Typical large-scale sewage-water treatments consume energy, occupy space and are unprofitable. This work evaluates a conceivable two-staged sewage-water treatment at 40,000 m3/d of sewage-water with sewage-sludge (totaling 10kgCOD/m3) that becomes a profitable bioenergy producer exporting reusable water and electricity, while promoting carbon capture. The first stage comprises microbial anaerobic digesters reducing the chemical oxygen demand (COD) by 95% and producing 60%mol methane biogas. The effluent waters enter the subsequent aerobic stage comprising microbial air-fed digesters that extend COD reduction to 99.7%. To simulate the process, up-to-date anaerobic/aerobic digester models were implemented. A biogas-combined-cycle power plant with/without post-combustion carbon capture is designed to match the biogas production, supplying electricity to the process and to the grid. Results comprehend electricity exportation of 13.21 MW (7.92 kWh/tReusable-Water) with -9.957tCO2/h of negative carbon emission (-0.6 kgCO2-Emitted/kgCOD-Removed). The biogas-combined-cycle without carbon capture achieves 21.08 MW of power exportation, while a 37.3% energy penalty arises if carbon capture is implemented. Configurations with/without carbon capture reach feasibility at 125 USD/MWh of electricity price, with respective net present values of 6.86 and 85.07 MMUSD and respective payback-times of 39 and 12 years. These results demonstrate that large-scale sewage-water treatment coupled to biogas-fired combined-cycles and carbon capture can achieve economically feasible bioenergy production with negative carbon emissions.


Asunto(s)
Aguas del Alcantarillado , Purificación del Agua , Anaerobiosis , Biocombustibles/análisis , Reactores Biológicos , Carbono , Metano , Eliminación de Residuos Líquidos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...