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1.
Sci Total Environ ; 912: 169101, 2024 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-38072267

RESUMO

Biowaste-derived hydrochar is an emerging close-to-natural product and has shown promise for soil improvement and remediation, but the environmental behavior of the dissolved organic matter released from hydrochar (HDOM) is poorly understood. Focusing on the typical mulch film plasticizer diethyl phthalate (DEP), we investigated the effect of HDOM on the sorption behavior of DEP on soil. The relatively low concentration of HDOM (10 mg L-1, 25 mg L-1) decreases the sorption quantity of DEP on soil, while it increases by a relatively high concentration, 50 mg L-1. The transformation from multilayer to monolayer sorption of DEP on soil occurs as the concentration of HDOM increases. The tryptophan-like substance is the main component of HDOM sorbed to soil, reaching 49.82 %, and results in competition sorption with DEP. The soil pores are blocked by HDOM, which limits the pore filling and mass transfer of DEP, but partitioning is significantly enhanced. The surface functional groups in HDOM are similar to those in soil, and chemical sorption, mainly composed of hydrogen bonding, exists but is not significantly strengthened. We identified the specific impact of HDOM on the sorption of organic pollutants on soil and provide new insights into the understanding of the environmental behavior of hydrochar.

2.
Chemosphere ; 321: 138138, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-36791817

RESUMO

Much research has been done on the preparation and application of hydrochars, but research on the release characteristics of hydrochar-derived dissolved organic matter (HDOM) is very limited; clarifying the release characteristics of HDOM is important for understanding and adjusting the environmental behaviour of hydrochar. Herein, the potential release of HDOM from rice straw-derived hydrochars prepared at different hydrothermal temperatures was investigated under various potential environmental conditions for the first time. The total release quantity and humification degree of HDOM decreased with increasing hydrothermal temperature. The critical dividing line for various hydrothermal reactions, decomposition and polymerization, was in the range of 240 °C-260 °C. Alkaline condition increased the HDOM release amount (up to 299 mg g-1), molecular weight (as high as 423 Da) and molecular diversity (8857 compounds) from rice straw-derived hydrochars. The unique substances of HDOM released under alkaline condition were mainly distributed in lipids-like substances, CRAM/lignins-like substances, aromatic structures, and tannins-like substances, while few unique substances were found under acidic condition. Additionally, CRAM/lignins-like substances were the most abundant in all HDOM samples, reaching 82%, which were relatively stable and could achieve carbon sequestration in different environments. The findings provided a new insight on understanding the potential environment behaviors of hydrochar.


Assuntos
Matéria Orgânica Dissolvida , Oryza , Temperatura , Lignina , Carbono/química
3.
Bioresour Technol ; 369: 128361, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36423753

RESUMO

Excellent biochar properties are crucial for sorption performance, and a developed pore structure is especially important. Herein, novel porous carbon/porous biochar (PC/PB) composites, in which the porous biochar and porous carbon were prepared at the same time, were synthesized via a green method from algal biomass with the help of the self-activation of citrate for the first time, and the composites were evaluated for the sorption of sulfamethoxazole (SMX). Many micro/meso/macropores were introduced into the PC/PB composites, which showed high specific surface areas (up to 1415 m2/g) and pore volumes (up to 1.08 cm3 g-1). The PC/PB composites displayed excellent SMX sorption capacities, which reached 844 mg g-1. Pore filling played a crucial role in determining the sorption capacity, and hydrogen bonding, electrostatic interactions and π-π stacking controlled the sorption rate. This study provides an improved method for preparation of porous biochar.


Assuntos
Alga Marinha , Sulfametoxazol , Sulfametoxazol/química , Ferro , Citrato de Potássio , Porosidade , Adsorção , Carvão Vegetal/química , Potássio
4.
Bioresour Technol ; 367: 128310, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36370946

RESUMO

Porous carbons are excellent sorbents for removing organic pollutants. Green conversion of biowaste into advanced porous carbons is crucial for industrialized production and practical applications, which, however, have rarely been investigated. This study develops a coassisted carbonization method for the preparation of porous carbons with the environmentally friendly agents HCOOK and (HCOO)2Ca for the first time. The bamboo waste-derived hydrochar was transformed into oxygen-doped porous carbons, which displayed a large surface area and pore volume, abundant oxygen content, graphene structure and many surface functional groups. These properties contributed to the extremely high sorption of large quantities of diethyl phthalate, which reached 761 mg g-1. Surface adsorption, including pore filling, hydrogen bonding, and π-π stacking, rather than partitioning, was the main sorption process. Therefore, this study provides a sustainable and promising route for the preparation of porous carbons that can be applied in the efficient removal of organic pollutants.


Assuntos
Poluentes Ambientais , Oxigênio , Porosidade , Carbono/química , Adsorção , Água/química
5.
RSC Adv ; 12(35): 22760-22769, 2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-36105956

RESUMO

Biochar has attracted great interest in both CO2 capture and supercapacitor applications due to its unique physicochemical properties and low cost. Fabrication of eco-friendly and cost-effective biochar from high potential biomass Tenebrio molitor feces can not only realize the functional application of waste, but also a potential way of future carbon capture and energy storage technology. In this study, a novel KOH activation waste-fed Tenebrio molitor feces biochar (TMFB) was developed and investigated in terms of CO2 capture and electrochemical performance. When activated at 700 °C for 1 h, the specific surface area of the feces biochar (TMFB-700A) increased significantly from 232.1 to 2081.8 m2 g-1. In addition, well-developed pore distribution facilitates CO2 capture and electrolyte diffusion. TMFB-700A can quickly adsorb a large amount of CO2 (3.05 mol kg-1) with excellent recycling performance. TMFB-700A also exhibited promising electrochemical performance (335.8 F g-1 at 0.5 A g-1) and was used as electrode material in a symmetrical supercapacitor. It provided a high energy density of 33.97 W h kg-1 at a power density of 0.25 kW kg-1 with 90.47% capacitance retention after 10 000 charge-discharge cycles. All the results demonstrated that TMFB could be a potential bifunctional material and provided valuable new insights for Tenebrio molitor feces high-value utilization.

6.
Front Plant Sci ; 13: 951181, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36119588

RESUMO

Precise and site-specific nitrogen (N) fertilizer management of vegetables is essential to improve the N use efficiency considering temporal and spatial fertility variations among fields, while the current N fertilizer recommendation methods are proved to be time- and labor-consuming. To establish a site-specific N topdressing algorithm for bok choy (Brassica rapa subsp. chinensis), using a hand-held GreenSeeker canopy sensor, we conducted field experiments in the years 2014, 2017, and 2020. Two planting densities, viz, high (123,000 plants ha-1) in Year I and low (57,000 plants ha-1) in Year II, whereas, combined densities in Year III were used to evaluate the effect of five N application rates (0, 45, 109, 157, and 205 kg N ha-1). A robust relationship was observed between the sensor-based normalized difference vegetation index (NDVI), the ratio vegetation index (RVI), and the yield potential without topdressing (YP0) at the rosette stage, and 81-84% of the variability at high density and 76-79% of that at low density could be explained. By combining the densities and years, the R 2 value increased to 0.90. Additionally, the rosette stage was identified as the earliest stage for reliably predicting the response index at harvest (RIHarvest), based on the response index derived from NDVI (RINDVI) and RVI (RIRVI), with R 2 values of 0.59-0.67 at high density and 0.53-0.65 at low density. When using the combined results, the RIRVI performed 6.12% better than the RINDVI, and 52% of the variability could be explained. This study demonstrates the good potential of establishing a sensor-based N topdressing algorithm for bok choy, which could contribute to the sustainable development of vegetable production.

7.
Bull Environ Contam Toxicol ; 109(4): 651-658, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35908225

RESUMO

Contaminated soils have caused serious harm to human health and the ecological environment due to the high toxicity of organic and inorganic pollutants, which has attracted extensive attention in recent years. Because of its low cost, simple operation and high efficiency, soil washing technology is widely used to permanently remove various pollutants in contaminated soils and is considered to be the most promising remediation technology. This review summarized the recent developments in the field of soil washing technology and discusses the application of conventional washing agents, advanced emerging washing agents, the recycling of washing effluents and the combination of soil washing and other remediation technologies. Overall, the findings provide a comprehensive understanding of soil washing technology and suggest some potential improvements from a scientific and practical point of view.


Assuntos
Recuperação e Remediação Ambiental , Metais Pesados , Poluentes do Solo , Poluição Ambiental , Humanos , Metais Pesados/análise , Solo , Poluentes do Solo/análise , Tecnologia
8.
Sci Total Environ ; 846: 157511, 2022 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-35872190

RESUMO

In this study, three high-performance porous biochars were synthesized by the cocarbonization of Pistia stratiotes-derived precursors (raw biomass, hydrochar and pyrochar) with potassium hydroxide and utilized for the sorption of diethyl phthalate from aqueous solution. The developed pore structure, surface functional groups, high hydrophobicity characteristic and graphene structure of porous biochars contributed to the excellent sorption quantity of up to 813 mg g-1 (Ce, 25 mg L-1). Among the three precursors, hydrochar-derived porous biochar showed better properties in terms of its specific surface area and hydrophobicity, and it displayed the highest sorption capacity. The sorption kinetics and isotherm experiments confirmed that pore filling and partitioning dominated the sorption capacity while the mass transfer, hydrogen bonding and π-π stacking in the hydrochar limited the sorption rate. This finding helped to propose a feasible method for the efficient utilization of invasive aquatic plants and provided novel insight into the selection of precursors for preparing porous biochars.


Assuntos
Carvão Vegetal , Ésteres , Adsorção , Biomassa , Carvão Vegetal/química , Ácidos Ftálicos , Porosidade
9.
Bioresour Technol ; 360: 127546, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35777643

RESUMO

In contrast to the efforts dedicated to applying porous biochars in environmental remediation, the search for green synthesis methods, which are crucial for industrialized production, is often neglected. Herein, oxygen-doped porous biochars were prepared for the first time by the assisted carbonization of hydrochar with a novel noncorrosive activator, potassium formate, and these biochars displayed a porous structure with large amounts of micropores (surface area: 1242 âˆ¼ 1386 m2 g-1). Interestingly, the biochars contained an abundance of oxygen element (20 âˆ¼ 26%), which formed many functional groups. Through sorption experiments, it was demonstrated that the oxygen-doped porous biochars were excellent sorbents for diethyl phthalate, and maximum sorption quantity reached 453 mg g-1. Monolayer sorption by pore filling, hydrogen bonding, electrostatic interaction and π-π stacking was the potential mechanism. This finding indicated that potassium formate was promising as an activator to greenly convert biowaste into advanced biochars for removing organic pollutants from aqueous solutions.


Assuntos
Poluentes Ambientais , Adsorção , Carvão Vegetal/química , Formiatos , Oxigênio , Porosidade , Água
10.
Waste Manag ; 144: 153-162, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35366496

RESUMO

Fluorescence excitation-emission matrix (EEM) spectroscopy is a powerful tool to characterize DOM that interacts with heavy metals in MSWI bottom ash (IBA). Here, two fresh IBA samples collected from large MSWI plants were subjected to 33 days of accelerated weathering. Carbon content and fluorescence characterization of DOM and leaching behavior of heavy metals (Cu, Ba, Cr, Ni, and oxyanions) were monitored during the weathering. The mineralogical and chemical properties of IBA during the weathering process were also characterized. EEM combined with parallel factor analysis showed that fluorescent DOM could be decomposed into humic-like (C1, C2) and tryptophan-like substances (C3), while the accelerated weathering process can be further divided into three phases. Fitted cubic polynomials described well the changes in the specific intensity of fluorescence components. Humification and freshness indexes and SUVA results suggested the leached DOM contained a higher proportion of condensed aromatic structures and/or conjugation of aliphatic chains post-weathering. The results also revealed that adsorption of humic-like substances onto neo-formed reactive surfaces occurred quickly in the early stage of accelerated weathering; thereafter, biodegradation of lower molecular mass-hydrophilic organic carbon fraction plays a vital role in further reduction of Cu and Cr leaching in subsequent weathering. Oxyanions (Mo and Sb) became more mobile after 3 days of accelerated weathering, but their leaching was effectively reduced after the weathering process. A novel method for an IBA weathering treatment combined with enhanced microbial degradation is proposed. These findings provide new and inspiration for improving accelerated weathering technology.


Assuntos
Cinza de Carvão , Metais Pesados , Carbono , Análise Fatorial , Substâncias Húmicas/análise , Espectrometria de Fluorescência/métodos
11.
Front Plant Sci ; 13: 864285, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35463444

RESUMO

Plant growth regulators are known to exert strong influences on plant performance under abiotic stress, including exposure to high nitrate, as occurs commonly in intensive vegetable production. However, direct comparative evaluations of growth regulators under otherwise identical conditions in major crop species are scarce. In this study, tomato (Solanum lycopersicum L.) was used as a model crop, and the roles of four common exogenously applied plant growth regulators (MT, melatonin; SA, salicylic acid; HA, humic acid; SNP, sodium nitroprusside) in regulating crop growth were studied under high-nitrate stress. We provide a particular focus on root system architecture and root physiological responses. Our data show that all four growth regulators improve tomato tolerance under high nitrate, but that this occurs to differing extents and via differing mechanisms. Optimal concentrations of MT, SA, HA, and SNP were 50 µmol L-1, 25 µmol L-1, 25 mg L-1, and 50 µmol L-1, respectively. MT and SNP produced the strongest effects. MT enhanced root growth while SNP enhanced above-ground growth. Growth of coarse and thin lateral roots was significantly improved. Furthermore, an enhancement of root vitality and metabolism, improved integrity of root cell membranes, and an increase in antioxidant enzyme activities were found, but regulatory mechanisms were different for each growth regulator. Our results show that in particular the application of MT and SNP can improve growth of tomato in intensive vegetable production under high-nitrate stress and that root growth stimulation is of special importance in procuring these beneficial effects.

12.
Bioresour Technol ; 346: 126604, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34953984

RESUMO

A one-pot co-pyrolysis of potassium/calcium carbonate with biowaste-derived hydrochar strategy was proposed to prepare hierarchical porous biochars (HPBs) for the first time. The pore structure, especially the pore size distribution, could be designed by adjusting the mass ratios of different carbonates. HPBs were hydrophobic, nitrogen doped, graphitized, and contained surface functional groups. HPBs showed unexpected sorption quantity for diethyl phthalate (DEP) that reached 657 mg g-1, which much higher than that of the reported sorbents. The sorption was multilayered and had multiple action modes, and was limited by the chemical sorption and the sorption quantity was dominated by the physical sorption. Lewis acid-base interaction, π-π stacking interaction, hydrogen bonding interaction, partitioning and pore filling were the potential sorption mechanisms. This work proposed a simple, environmentally friendly and low-cost method to convert biowaste into advanced HPBs and confirmed that produced HPBs represent ideal sorbents for the removal of organic pollutants.


Assuntos
Carbonato de Cálcio , Pirólise , Adsorção , Cálcio , Carbonatos , Carvão Vegetal , Ácidos Ftálicos , Porosidade , Potássio
13.
Chemosphere ; 280: 130712, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33971415

RESUMO

Invasive plants pose a significant threat to natural ecosystems because of their high adaptability, rapid propagation and spreading ability in the environment. In this study, a typical aquatic invasive plant, Pistia stratiotes, was chosen as a novel feedstock for the preparation of nitrogen-doped biochars (NBs) for the first time, and the NBs were used as efficient sorbents to remove phthalate esters (PAEs) from aqueous solution. Characterization results showed that NBs possess great pore structure (up to 126.72 m2 g-1), high nitrogen (2.02%-2.66%) and ash (24.7%-34.1%) content, abundant surface functional groups, hydrophobicity and a graphene structure. Batch sorption experiments were performed to investigate the sorption performance, processes and mechanisms. The capacities for PAEs sorption onto NBs were high, especially with NBs pyrolyzed at 700 °C, ranging up to 161.7 mg g-1 for diethyl phthalate and 85.4 mg g-1 for dibutyl phthalate; these levels were better than many reported for other sorbents. With kinetic and isotherm results, Pseudo-second order and Freundlich models fit the sorption data well, and chemical interactions involving hydrogen bonding, Lewis acid-base interaction, functional group interaction, cation-π interaction and π-π stacking interaction were identified as possible rate-limited steps. Moreover, Intra-particle diffusion and Dubinin-Radushkevich models indicated that multiple pore filling and partitioning dominated the process of PAEs sorption onto NBs. This study opens the door for new methods of pollution control with waste treatment, since invasive plant biomass resources were converted into advanced biochars for efficient environmental remediation.


Assuntos
Ésteres , Nitrogênio , Adsorção , Carvão Vegetal , Ecossistema , Ácidos Ftálicos , Pirólise
14.
Sci Total Environ ; 781: 146712, 2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-33812102

RESUMO

Potential release quantity and quality of dissolved organic matter (DOM) from hydrochar (HDOM) in various environmental conditions were investigated. Corn cobs were utilized as model agricultural residue to prepare the hydrochar. Four extracts, ultra-pure water, acid solution, alkali solution and salt solution, and two temperatures, 20 °C and 60 °C, were adopted to imitate various environmental conditions. Excitation-emission spectrophotometry with parallel factor analysis was used to evaluate the chemical properties of HDOM. The results showed that the dissolved organic carbon in the HDOM was high, ranging from 46 to 268 mg g-1. Four components were confirmed in the HDOM: mixed substances of humic-like and protein-like components, marine humic-like substances, terrestrial humic-like substances and tyrosine-like substances. Alkalinity and high temperature conditions could enhance the leaching amount of HDOM, particularly humic-like substances, and change the relative proportion of components and the chemical quality. In addition, values of the fluorescence indexes indicated that the HDOM was high microbial availability. Released HDOM may result in significant impacts in ecosystem functionality. These findings reveal the potential release characteristics of HDOM in the environment, opening new doors to understanding the environmental impacts of hydrochar and guiding its rational application.

15.
RSC Adv ; 11(24): 14347-14356, 2021 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-35423965

RESUMO

Fluorescence excitation-emission matrix (EEM) spectroscopy is a powerful tool for characterizing dissolved organic matter (DOM), a key component of anaerobic digestion. In this study, the fluorescence characteristics of DOM during 55 days of anaerobic digestion of oil crop straw inoculated with rumen liquid were investigated. EEM spectroscopy coupled with parallel factor analysis (PARAFAC) showed that three major fluorescence components, tyrosine- (C1), humic- (C2) and tryptophan-like substances (C3), were identified in all DOM samples. The F max values of C1 and C3 increased rapidly during the first 5 d, decreased dramatically from day 5 to day 35, and then remained stable, while C2 was not biodegraded. The changes in the F max values of the fluorescence components reflected the biodegradation of lignin and/or embedded cellulose by rumen microorganisms. The changes in the Stokes shift of the fluorescence peak were readily explained by the variation in the hydrophobic/hydrophilic fraction distribution. The humidification index (HIX) and A : T ratio of the DOM decreased after 5 d and then increased gradually. Compared with the McKnight fluorescence index (MFI), the Y fluorescence index (YFI) was better able to track the evolution of the DOM. Correlation analysis of the different fluorescence indices (intensities) and absorbance indices was also carried out. The EEM-PARAFAC individual components, HIX and A : T ratio were conveniently used to characterize the degree of anaerobic conversion of the organic matter, and the peak at the Stokes shift of ∼1.0 µm-1 was used as one of the indicators showing the stabilization of anaerobic digestion. These findings may assist in developing fluorescence technology for monitoring the anaerobic digestion of crop straw.

16.
J Hazard Mater ; 407: 124785, 2021 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-33348203

RESUMO

Nitrogen-doped porous biochar (NPB) with a large specific surface area, wide pore size distribution, graphitized structure, nitrogen doping, and hydrophobicity was fabricated by high-temperature modification of algal biochar with potassium carbonate. This NPB was then uniformly coated on stainless steel wire as a novel solid-phase microextraction (SPME) fiber. The extraction efficiency of NPB-coated fiber for seven chlorobenzenes (CBs) was excellent; it was 1.0-112.2 times higher than that of commercial SPME fibers. A trace determination method was developed for seven CBs in water with the optimized extraction conditions by NPB-coated fiber and gas chromatography-electron capture detector, which showed wide linear ranges (1-1000 ng L-1), low detection limits (0.007-0.079 ng L-1), great repeatability (2.5-6.5% for intra-day, and 3.1-6.8% for inter-day), and excellent reproducibility (3.5-6.3%, n = 5). The practicality of the developed method was evaluated using real water samples and showed great recoveries (89.55-105.19%). This study showed that low-cost biomass wastes could be converted to advanced biochar materials by a facile method, and displayed excellent performance in SPME applications.


Assuntos
Microextração em Fase Sólida , Poluentes Químicos da Água , Carvão Vegetal , Clorobenzenos , Nitrogênio , Porosidade , Reprodutibilidade dos Testes , Água , Poluentes Químicos da Água/análise
17.
Archaea ; 2020: 8841490, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33223962

RESUMO

Thermophilic solid-state anaerobic digestion (SS-AD) of agricultural wastes, i.e., corn straw, cattle manure, and vegetable waste, was carried out in this study. The effects of temperature (40-60°C), initial solid content (ISC, 17.5-32.5%), and C/N ratio (15-32 : 1) on biogas production were evaluated using a Box-Behnken experimental design (BBD) combined with response surface methodology (RSM). The results showed that optimization of process parameters is important to promote the SS-AD performance. All the factors, including interactive terms (except the ISC), were significant in the quadratic model for biogas production with SS-AD. Among the three operation parameters, the C/N ratio had the largest effect on biogas production, followed by temperature, and a maximum biogas yield of 241.4 mL gVS-1 could be achieved at 47.3°C, ISC = 24.81%, and C/N = 22.35. After 20 d of SS-AD, the microbial community structure under different conditions was characterized by high-throughput sequencing, showing that Firmicutes, Bacteroidetes, Chloroflexi, Synergistetes, and Proteobacteria dominated the bacterial community, and that Firmicutes had a competitive advantage over Bacteroidetes at elevated temperatures. The biogas production values and relative abundance of OPB54 and Bacteroidia after 20 d of SS-AD can be fitted well using a quadratic model, implying that OPB54 and Bacteroidia play important roles in the methanogenic metabolism for agricultural waste thermophilic SS-AD.


Assuntos
Anaerobiose/fisiologia , Carbono/química , Esterco/microbiologia , Nitrogênio/química , Verduras/química , Zea mays/química , Animais , Bactérias/crescimento & desenvolvimento , Biocombustíveis/microbiologia , Reatores Biológicos/microbiologia , Bovinos , Microbiota/fisiologia , Temperatura
18.
Bioresour Technol ; 303: 122947, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32045865

RESUMO

Enhanced macroalgal biochars with large specific surface areas (up to 399 m2 g-1), partly graphitized structure, high nitrogen doping (up to 6.14%), and hydrophobicity were fabricated by co-carbonization of macroaglae, ferric chloride, and zinc chloride. These biochars were used as sorbents for the removal of polycyclic aromatic hydrocarbons from water. The sorption capacity of polycyclic aromatic hydrocarbons onto macroalgal biochars was high (up to 90 mg g-1), and recycling by thermal desorption was practicable. We revealed the physical-dominated multilayer sorption process, based on results from characterization and sorption experiments. Pore filling, mass transfer, π-π stacking, and the partition effect were found to be possible sorption mechanisms. This study suggests that porous graphitized nitrogen-doped biochars may be synthesized from macroalgae with simple one-pot carbonization and display promising applicability for sorption removal of organic pollutants from water.


Assuntos
Hidrocarbonetos Policíclicos Aromáticos , Alga Marinha , Adsorção , Biota , Carvão Vegetal , Nitrogênio , Porosidade
19.
Sci Total Environ ; 681: 392-399, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31108359

RESUMO

There is urgent demand for the design of advanced coating materials for solid-phase microextraction (SPME) for water quality monitoring and assessment because of the global occurrence of chlorobenzenes (CBs). In this study, we proposed a dual-order activation method in which potassium hydroxide is used to modify pre-activated calcium citrate to synthesize a highly developed meso-/microporous carbon (MMC). The as-obtained MMC presented well-developed porosity with a super-high specific surface area (2638.09 m2 g-1), abundant meso-/micropores (0.5-10 nm), high hydrophobicity, excellent thermal stability (>720 °C), and a partly graphitized structure. As a coating material for headspace-SPME, the MMC-coated fiber exhibited outstanding extraction capability for CBs (up to 48.5 times higher than that of commercial fibers), which may be attributed to multiple interactions between the MMC and the pollutants, including size selectivity, micropore filling, π-π stacking and hydrophobicity. Finally, a satisfactory method using an MMC-coated fiber coupled with gas chromatography and electron capture detection was developed with good linearity (1-1000 ng L-1, R2 > 0.9982), high enrichment efficiencies (enrichment factors, 861-7819), low limits of detection (0.003-0.072 ng L-1), excellent repeatability (0.7-5.3%) and reproducibility (1.7-5.1%), and outstanding recoveries (90.18-103.02%) when applied to determine trace CBs in real water samples. These results suggest that MMC is a promising coating material for the SPME of CBs.

20.
Bioresour Technol ; 284: 1-8, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30925418

RESUMO

In this study, rape straw- and corn cob-derived porous carbons (PCs) were fabricated by hydrothermal treatment (250 °C, 4 h) and subsequent activation (850 °C, 1 h) using a non-corrosive agent, potassium bicarbonate. The PCs exhibited a very large specific surface area (1069-1281 cm2 g-1), high pore volume (0.55-0.72 cm3 g-1), wide pore size distribution (from micropores to macropores), high hydrophobicity, and partly graphitized structure. These properties contributed to highly efficient performance for the sorption of polycyclic aromatic hydrocarbons (PAHs), with maximum sorption capacities of 592.97, 480.27, and 692.27 mg g-1 towards naphthalene, acenaphthene, and phenanthrene, respectively. A three-step sorption process with pore filling, hydrophobic effects, and π-π stacking interactions on the heterogeneous surface is a possible mechanism for the sorption of PAHs onto PCs. This study presents an environmentally friendly strategy for the reuse of crop residues in the field of organic micropollutant-contaminated water treatment.


Assuntos
Carbono/química , Naftalenos/isolamento & purificação , Fenantrenos/isolamento & purificação , Poluentes Químicos da Água/química , Água/química , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Cinética , Porosidade
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