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1.
Environ Sci Pollut Res Int ; 27(1): 1167-1174, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31820254

RESUMO

Transport and retention of nano PbO (nPbO) in quartz sand-alluvial soil mixture column and alluvial soil column were investigated. The dissolution kinetics of nano size lead chemicals in alluvial soil and nPbO in different soils were investigated through aging experiment and batch extraction experiment. nPbO was trapped mainly near the inlet of both quartz sand-alluvial soil mixture column and alluvial soil column. pH value (6, 7, and 8) and ion strength (1 and 10 mM CaCl2) did not have obvious effect on the retention of nPbO. nPbO, nPbSO4, and nPbCO3 experienced distinguishable dissolution in alluvial soil, but had similar dissolution trend. The dissolution kinetics of nPbO in alluvial soil and black soil were similar, increasing fast at 0-60 days and then slowing down. The dissolution of nPbO in red soil extracted by using HCl solution, CaCl2 solution and deionized water increased obviously from 90 to 180 days, differed from that by using EDTA extraction. The dissolution kinetics from three contaminated soils assessed by EDTA was similar. Overall, although nPbO had much weaker transport than Pb (II), dissolution would improve its mobility greatly.

2.
Environ Sci Pollut Res Int ; 26(3): 2523-2530, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30471065

RESUMO

In order to remove aqueous radionuclides and find an appropriate method for the disposal of wild duckweed in eutrophic water body, alkali-treated duckweed biomass and duckweed-based hydrothermal biochar (hydrochar) and pyrolytic biochars of 300 and 600 °C were prepared. Their physicochemical properties were characterized carefully. The adsorption isothermal data fitted well with the Langmuir model and the maximum Langmuir adsorption capacities were 104.1, 96.3, 86.7, and 63.5 mg/g for hydrochar, modified biomass, and 300 and 600 °C biochars, respectively. The adsorption kinetic data fitted well with the pseudo-second-order kinetic equation. The sorption data of fixed-bed column also confirmed the high efficient removal of Th(IV) and fitted well with the Thomas model. The duckweed-based hydrothermal biochar is a low-cost adsorbent for Th(IV) removal, and it is also a resource utilization technology of the duckweed collected from eutrophic water body.


Assuntos
Carvão Vegetal/química , Tório/química , Adsorção , Álcalis/química , Biomassa , Cinética , Pirólise , Poluentes Químicos da Água/análise , Purificação da Água/métodos
3.
Environ Sci Pollut Res Int ; 25(26): 26059-26068, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29968219

RESUMO

The airborne particle-bound elements (Ca, Fe, Al, Mg, K, Na, Zn, Mn, P, Pb, Cu, Sr, Ti, Ba, Cr, Ni, As, Sb, Cd, Co, and V) trapped in room air conditioners' filters (filter dusts) during recirculating indoor air from different types of rooms were analyzed, and the objectives of this study were to assess the potential sources of those elements and their potential health risks via inhalation/ingestion exposure. Main crustal elements such as Ca, Fe, Al, Mg, and K with an average value of 60.6, 17.9, 11.3, 7.58, and 6.90 mg g-1, respectively, are the preponderant elements, and the mean values of main toxic elements were 2230, 344, 508, 85.7, 71.5, 36.0, 8.02, and 16.9 mg kg-1 for Zn, Cu, Pb, Cr, Ni, As, Cd, and Sb, respectively. The enrichment factors indicated the significant enrichment of Cd, Pb, Cr, Cu, Sb, and Zn in the filter dusts. Four potential sources with the contributions of 33.5, 29.1, 22.6, and 14.8%, respectively, were identified by absolute principal component scores-multiple linear regression analysis (APCS-MLR). Enrichment factor and APCS-MLR model reveal the outdoor input of toxic elements. In vitro inhalation and ingestion bioaccessibility of toxic elements showed elemental and in vitro procedure dependence. There are potential carcinogenic risks via ingestion exposure and no non-carcinogenic risks to both children and adults based on bioaccessible contents of toxic elements. This study reveals the potential health risks posed by the particle-bound elements.


Assuntos
Ar Condicionado , Filtros de Ar , Poluição do Ar em Ambientes Fechados , Poeira/análise , Monitoramento Ambiental , Exposição por Inalação , Adulto , Criança , China , Monitoramento Ambiental/métodos , Humanos , Metais Pesados/análise , Análise Multivariada , Medição de Risco
4.
Chemosphere ; 208: 800-807, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29906754

RESUMO

In order to develop promising sorbents for value-added application of solid wastes, low-cost aluminum-enriched biochar was prepared from abandoned Tetra Pak used to hold milks, a paper-polyethylence-Al foil laminated package box, after acid pretreatment and subsequent slow pyrolysis under an oxygen-limited environment at 600 °C. The basic physicochemical properties of the resultant biochar were characterized and the sorption performance of aqueous As(III) and As(V) was investigated via batch and column sorption experiments. Carbon (49.1%), Ca (7.41%) and Al (13.5%) were the most abundant elements in the resultant biochar; and the specific surface area and the pH value at the point of zero charge (pHPZC) were 174 m2 g-1 and 9.3, respectively. Batch sorption showed excellent sorption performance for both As(III) (24.2 mg g-1) and As(V) (33.2 mg g-1) and experimental data were fitted well with Langmuir model for the sorption isotherms and pseudo-second order kinetic model for the sorption kinetics. The residual concentrations of As(V) after sorption were below the limited value of arsenic in WHO Guidelines for Drinking water Quality (0.01 mg L-1) even if coexistence of PO43-. Column sorption confirmed the high sorption performance for As(III) and As(V). So the slow pyrolysis of abandoned Tetra Paks as low-cost and value-added sorbents is a sustainable strategy for solid waste disposal and wastewater treatment.


Assuntos
Arsênico/química , Carvão Vegetal/química , Adsorção , Alumínio , Poluentes Químicos da Água/análise , Purificação da Água/métodos
5.
Chemosphere ; 189: 76-85, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28930666

RESUMO

The potential release of toxic elements and the stability of carbon in sludge-based biochars are important on their application in soil remediation and wastewater treatment. In this study, municipal sludge was co-pyrolyzed with calcium carbonate (CaCO3) and calcium dihydrogen phosphate [Ca(H2PO4)2] under 300 and 600 °C, respectively. The basic physicochemical properties of the resultant biochars were characterized and laboratory chemical oxidation and leaching experiments of toxic elements were conducted to evaluate the chemical stability of carbon in biochars and the potential release of toxic elements from biochars. Results show that the exogenous minerals changed the physico-chemical properties of the resultant biochars greatly. Biochars with exogenous minerals, especially Ca(H2PO4)2, decreased the release of Zn, Cr, Ni, Cu, Pb, and As and the release ratios were less than 1%. Tessier's sequential extraction analysis revealed that labile toxic elements were transferred to residual fraction in the biochars with high pyrolysis temperature (600 °C) and exogenous minerals. Low risks for biochar-bound Pb, Zn, Cd, As, Cr, and Cu were confirmed according to risk assessment code (RAC) while the potential ecological risk index (PERI) revealed that the exogenous Ca(H2PO4)2 significantly decreased the risks from considerable to moderate level. Moreover, the exogenous minerals significantly increased the chemical stability of carbon in 600 °C-pyrolyzed biochars by 10-20%. These results indicated that the copyrolysis of sludge with phosphate and carbonate, especially phosphate, were effective methods to prepare the sludge-based biochars with immobilized toxic elements and enhanced chemical stability of carbon.


Assuntos
Carbonato de Cálcio/química , Fosfatos de Cálcio/química , Carbono/química , Carvão Vegetal/química , Esgotos/química , Carvão Vegetal/toxicidade , Temperatura Alta , Metais Pesados/química , Minerais/química , Solo/química , Águas Residuárias/química
6.
Environ Sci Pollut Res Int ; 23(2): 1905-15, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26408115

RESUMO

Biochar as soil amendment can increase soil carbon (C) sequestration and mineral nutrients; however, some of its soluble elements may also be unintentionally released during the application. In this work, eight types of biochars were derived from herbaceous, woody, and waste (tailing, manure, sludge) biomass feedstocks through slow pyrolysis at 600 °C in N2. The elemental composition, specific surface area, morphology, crystalline phases, thermal stability, surface functional groups, and pH of the point of zero charge of the biochars were determined using various methods. These properties varied significantly among the tested biochars, suggesting that feedstock type played an important role in controlling their properties. Laboratory release and toxicity characteristic leaching procedure extraction experiments were conducted to evaluate the potential release of nutritious and toxic element from biochars. Results showed that all the biochars released nutritious elements and thus, may be beneficial to plants when amended in soils. In general, biochars produced from herbaceous and woody biomass feedstocks showed low risks of releasing toxic elements. Biochar derived from sludge, however, might present ecotoxicological challenges for its environmental applications due to the release of toxic elements, such as heavy metals.


Assuntos
Carvão Vegetal/química , Esterco/análise , Esgotos/química , Biomassa , Metais Pesados/análise , Solo/química , Madeira/química
7.
Water Res ; 68: 206-16, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25462729

RESUMO

Iron (Fe)-impregnated biochar, prepared through a novel method that directly hydrolyzes iron salt onto hickory biochar, was investigated for its performance as a low-cost arsenic (As) sorbent. Although iron impregnation decreased the specific surface areas of the biochar, the impregnated biochar showed much better sorption of aqueous As (maximum sorption capacity of 2.16 mg g⁻¹) than the pristine biochar (no/little As sorption capacity). Scanning electron microscope equipped with an energy dispersive spectrometer and X-ray diffraction analysis indicated the presence of crystalline Fe hydroxide in the impregnated biochar but no crystal forms of arsenic were found in the post-sorption biochar samples. However, large shifts in the binding energy of Fe2p, As3d, O1s and C1s region on the following As sorption indicated a change in chemical speciation from As(V) to As(III) and Fe(II) to Fe(III) and strong As interaction with oxygen-containing function groups of the Fe-impregnated biochar. These findings suggest that the As sorption on the Fe-impregnated biochar is mainly controlled by the chemisorption mechanism. Columns packed with Fe-impregnated biochar showed good As retention, and was regenerated with 0.05 mol L⁻¹ NaHCO3 solution. These findings indicate that Fe-impregnated biochar can be used as a low-cost filter material to remove arsenic from aqueous solutions.


Assuntos
Arsênico/química , Carvão Vegetal/química , Filtração/métodos , Ferro/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Hidrólise
8.
Bioresour Technol ; 167: 569-73, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24998306

RESUMO

Sorption and cosorption of lead (Pb(II)) and methylene blue (MB) in aqueous solutions on low-cost biosorbents made from chemically modified agricultural by-products was investigated. Modified cotton exhibited the highest adsorption capacity for Pb(II), while modified cotton and peanut hull had higher equilibrium adsorption capacity of MB than the other biosorbents. Different chemical modification methods of hickory resulted in no great variation on the equilibrium adsorption capacity of Pb(II) and MB except for the one treated with alkali. Simultaneous sorption of Pb(II) and MB on the biosorbents showed Pb(II) to be preferentially adsorbed at higher Pb(II)-to-MB molar ratios in solution except for modified peanut hull. The equilibrium Pb adsorption contents decreased with the increasing pre-loading of MB and vice versa, suggesting the competitive rather than synergistic adsorption of the two contaminants on the biosorbents.


Assuntos
Biomassa , Chumbo/isolamento & purificação , Azul de Metileno/isolamento & purificação , Adsorção , Biodegradação Ambiental , Cátions , Troca Iônica , Temperatura Ambiente
9.
Guang Pu Xue Yu Guang Pu Fen Xi ; 34(2): 358-63, 2014 Feb.
Artigo em Chinês | MEDLINE | ID: mdl-24822401

RESUMO

The changes of UV-Vis and FTIR spectroscopic properties for capsanthin before and after reaction with exogenous superoxide anion (*O2(-)), hydrogen peroxide (H2O2) and hydroxyl radical (*OH), catalase (CAT), peroxidase (POD) and lipoxygenase (LOX) were explored. The results showed that, the UV-Vis spectral absorption of capsanthin treated with reactive oxygen species had a blue-shift. At the same time, the FTIR spectra changed significantly. The number of FTIR spectral peaks reduced and theFTIR strength weakened for capsanthin molecule treated with *O2(-) and *OH. The characteristic and strong peaks moved to shorter wavelengths when treated with H2O2. And LOX caused breakage of capsanthin molecule and reduction of peak number or groups without carbonyl. Exogenous H2O2 + CAT or H2O2 + POD treatment could not affect the UV-Vis and FTIR spectra significantly. So ROS could cause oxidative degradation of capsanthin and destroy chromophoric groups such as carbon-carbon double bond and carbonyl, then grow colorless alcohols. Hence ROS and LOX should transforms the conjugate system of capsanthin molecules, while CAT and POD could protect the capsanthin.


Assuntos
Catalase/química , Peróxido de Hidrogênio/química , Radical Hidroxila/química , Oxirredução , Peroxidases/química , Espécies Reativas de Oxigênio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Superóxidos/química , Xantofilas/química
10.
Environ Pollut ; 187: 42-8, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24440437

RESUMO

Lead levels and isotopic compositions in atmospheric particles (TSP and PM2.5), street dust and surface soil collected from Nanjing, a mega city in China, were analyzed to investigate the contamination and the transfer of lead in urban environmental compartments. The lead contents in TSP and PM2.5 are significantly higher than them in the surface soil and street dust (p < 0.05). The enrichment factor using the mass ratio of lead to the major crustal elements (Al, Sr, Ti and Fe) indicates significant lead enrichment in atmospheric particles. The plots of (206)Pb/(207)Pb vs.(208)Pb/(206)Pb and (206)Pb/(207)Pb vs. 1/Pb imply that the street dust and atmospheric particles (TSP and PM2.5) have very similar lead sources. Coal emissions and smelting activities may be the important lead sources for street dust and atmospheric particles (TSP and PM2.5), while the deposition of airborne lead is an important lead source for urban surface soil.


Assuntos
Cidades/estatística & dados numéricos , Monitoramento Ambiental , Poluentes Ambientais/análise , Chumbo/análise , China , Carvão Mineral , Poeira/análise , Solo/química , Poluentes do Solo/análise
11.
Environ Geochem Health ; 36(3): 399-408, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24026570

RESUMO

In order to investigate the ecological and human health risks of metal(loid)s (Cu, Pb, Zn, Ni, Cd, Mn, Cr, and As) in peri-urban soils, 43 surface soil samples were collected from the peri-urban area around Nanjing, a megacity in China. The average contents were 1.19, 67.8, 37.6, 105, 167, 44.6, 722, and 50.8 mg kg(-1) for Cd, Cr, Ni, Pb, Zn, Cu, Mn, and As, respectively. A significant positive correlation was found between Cu, Pb, Zn, Cd, Mn, and As (p < 0.01), and Cr had a significant positive correlation with Ni (p < 0.01). Geoaccumulation indices indicate the presence of Cd and As contamination in all of the peri-urban soil samples. Potential ecological risk indices show that the metal(loid)s in the soil could result in higher ecological risks. Cd is the main contributor to the risk, followed by As. The levels of Cu, Pb, Zn, Cd, Mn, and As in stomach and intestinal phases show a positive linear correlation with their total contents. Mn, Zn, Ni, Cd, and Pb in stomach phase showed higher bioaccessibility, while in intestinal phase, Cu, Cr, and As had the higher bioaccessibility. The carcinogenic risk in children and adults posed by As, Pb, and Cr via ingestion was deemed acceptable. The non-carcinogenic risks posed by these metal(loid)s via ingestion to children are higher than to adults and mainly result from As.


Assuntos
Ecologia , Metais/toxicidade , Poluentes do Solo/toxicidade , Adulto , Disponibilidade Biológica , Criança , China , Humanos , Metais/farmacocinética , Medição de Risco , Poluentes do Solo/farmacocinética
12.
Environ Pollut ; 159(5): 1215-21, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21345560

RESUMO

The oral bioaccessibility and the human health risks of As, Hg and other metals (Cu, Pb, Zn, Ni, Co, Cd, Cr, Mn, V and Fe) in urban street dusts from different land use districts in Nanjing (a mega-city), China were investigated. Both the total contents and the oral bioaccessibility estimated by the Simple Bioaccessibility Extraction Test (SBET) of the studied elements varied with street dusts from different land use districts. Cd, Zn, Mn, Pb, Hg and As showed high bioaccessibility. SBET-extractable contents of elements were significantly correlated with their total contents and the dust properties (pH, organic matter contents). The carcinogenic risk probability for As and Cr to children and adults were under the acceptable level (<1×10(-4)). Hazard Quotient values for single elements and Hazard Index values for all studied elements suggested potential non-carcinogenic health risk to children, but not to adults.


Assuntos
Arsênico/análise , Carcinógenos Ambientais/análise , Poeira/análise , Exposição Ambiental/análise , Metais Pesados/análise , Adulto , Disponibilidade Biológica , Criança , China , Cidades , Humanos , Medição de Risco
13.
Bull Environ Contam Toxicol ; 82(1): 80-4, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18795215

RESUMO

Lead/cadmium contamination in vegetables grown in peri-urban area of Nanjing, China was assessed and the route for metals entering into plants was investigated through lead isotopic tracing. Results show that agricultural soils have been polluted with Cd. Contents of Pb (22.1-37.5 mg kg(-1 )dw) and Cd (2.53-4.19 mg kg(-1) dw) in vegetables' edible parts nearby a lead/zinc mining/smelting plant were beyond their maximum allowable limit prescribed in the (EC) No 1881/2006. Pb isotope ratios in plants differed from those in the corresponding soils, suggesting that soils were not the only contamination source of Pb and Cd in plants.


Assuntos
Agricultura , Cádmio/análise , Resíduos Industriais , Isótopos/análise , Chumbo/análise , Poluentes do Solo/análise , Verduras/metabolismo , Cádmio/metabolismo , Cádmio/toxicidade , China , Cidades , Isótopos/metabolismo , Isótopos/toxicidade , Chumbo/metabolismo , Chumbo/toxicidade , Metalurgia , Mineração , Medição de Risco , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade , Verduras/crescimento & desenvolvimento
14.
Chemosphere ; 48(6): 621-9, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12143937

RESUMO

Through short-term exposure (7-d exposure), long-term exposure (16-d exposure) and exposure-recovery (7-d exposure + 9-d recovery), the bioaccumulation and distribution of La and Ce and their effects on growth of wheat seedlings were studied. Addition of La (0.5-25 mg/l) and Ce (0.5-25 mg/l) to the culture medium individually and in combination inhibited primary root elongation, reduced the dry weight of roots and shoots and the content of mineral elements (Ca, Mg, K, Cu, Zn). The damage increased with an increase in the concentrations of La and Ce in culture medium. Relative damage ratio increased with an increase in concentrations of La and Ce in the culture medium and with exposure time. Comparing exposure-recovery groups with long-term exposure groups, primary root lengths, dry weight of roots and shoots and the content of five mineral elements were higher. The accumulation of La and Ce in the seedlings was positively correlated with the concentrations of La and Ce in the culture medium and with exposure time. Bioaccumulation factors of La and Ce in roots were much higher than those of shoots. The uptake rates of La and Ce by the plants were much higher than the translocation rates from roots to shoots. The accumulation and distribution of La and Ce in the seedlings in exposure-recovery groups showed that there was very little excretion through metabolism during the recovery period, but redistribution occurred throughout the whole plant. No apparent selective uptake was found between La and Ce by the plants when they were applied in combination.


Assuntos
Cério/efeitos adversos , Cério/farmacocinética , Lantânio/efeitos adversos , Lantânio/farmacocinética , Triticum/fisiologia , Interações de Medicamentos , Folhas de Planta/química , Raízes de Plantas/química , Plântula/crescimento & desenvolvimento , Distribuição Tecidual , Triticum/crescimento & desenvolvimento
15.
Huan Jing Ke Xue ; 23(1): 97-102, 2002 Jan 30.
Artigo em Chinês | MEDLINE | ID: mdl-11987417

RESUMO

The effect of soil pH value on the bioavailability and fractionation of rare earth elements (REEs) in wheat seedling (Triticum aestivum L.) were investigated. The results showed that the concentration of REEs in wheat decreased with increasing pH value, and their inter-relationship was best expressed as quadratic equation, with correlation coefficients from 0.6003 to 0.9572. The response of individual elements to pH value change tended to be Ce > La > Nd > Sm > Gd > Yb > Eu, with Ce most sensitive to changing pH conditions and Eu lest. Chemical fractionation indicated that the order of REEs concentration in three fractions could be as follows: B2(NH2OH.HCl extraction) > B3(H2O2-NH4Ac extract) > B1(HAc extract). The increase of pH value resulted in transformation from B1 to B2 and B3. Multiple regression analysis was utilized to obtain the regression equations for prediction plant uptake of REEs. B1 fraction was most available to wheat. Meanwhile, it was found that the fractionation factors of REEs in wheat were negatively correlated with the soil pH value.


Assuntos
Metais Terras Raras/metabolismo , Solo/análise , Triticum/metabolismo , Disponibilidade Biológica , Concentração de Íons de Hidrogênio , Metais Terras Raras/isolamento & purificação
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