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1.
Chemosphere ; 260: 127639, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758767

RESUMO

Lipids are biomolecules extracted from plant sources and plant residues and have a beneficial role in various food, nutrition and medical applications. Supercritical carbon-dioxide as an advanced high-pressure technology which increases the productivity and has negligible environmental impact is employed for the selective extraction of polar lipids from the lipid matrix in mango kernel for the first time. The process parameters affecting the extraction such as pressure, temperature and the flow rate of CO2 are ranged in the intervals of 30-50 MPa, 40-60 °C and 10-30 g min-1, respectively. Optimization using Box Behnken design obtained the highest yield of 3.38% at 40 °C, 50 MPa and 30 g min-1. The phosphorous content was evaluated to understand the behaviour of polar lipids extraction at higher pressures. The study showed the effect of process parameters having significant influence on polarity and solvating capacity of CO2 which enabled for the extraction of polar lipids adding value to the mango kernel converting waste into valuable industrial products. The economic evaluation estimates the return on investment of a plant processing 3000 tons of mango kernel per year to account net present value (NPV) almost five times higher than the investment expenses and the payback period is under 4 years.


Assuntos
Dióxido de Carbono/química , Fósforo/química , Cromatografia com Fluido Supercrítico , Análise Custo-Benefício , Lipídeos/química , Mangifera , Extratos Vegetais/química , Temperatura
2.
Chemosphere ; 259: 127395, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32623200

RESUMO

In this work, iron (oxyhydr)oxide nanoparticle-doped expanded graphite (IO/EG-1 and IO/EG-2) was prepared via a hydrothermal reaction and applied for the phosphorus adsorption in the aqueous solutions. The analysis of scanning electron microscopy (SEM) and X-ray diffraction (XRD) verified the successful fabrication of IO/EGs, and iron (oxyhydr)oxide nanoparticles became more crystalized according to the calcination at high temperature (IO/EG-2). The maximum adsorption capacity of IO/EG-1 was considerably higher (7.30 mg/g) than that of IO/EG-2 (0.70 mg/g) mainly due to the electrostatic interaction between the negatively charged phosphate ions with iron (oxyhydr)oxides. At the neutral pH, IO/EG-1 exhibited more positively charged than IO/EG-2, which the iso-electric points (IEP) were pH of 9.1 and 6.0, respectively. The thermodynamic study also suggested that the phosphorus adsorption energy of IO/EG-1was considerably favorable (-12.13 kJ/mol) than that of IO/EG-2 (-7.43 kJ/mol). The regeneration of IO/EG-1 were efficiently achieved by a simple extraction using an alkaline solution such as NaOH. Overall, our study suggested that the prepared IO/EGs could be used as good adsorbents for the phosphorus recovery from aqueous solutions.


Assuntos
Grafite/química , Fósforo/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Ferro/química , Nanopartículas , Óxidos , Fosfatos , Termodinâmica , Difração de Raios X
3.
Chemosphere ; 259: 127469, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32640377

RESUMO

In this study, Mg and/or Al modified biochars (MABC1, MBC2, ABC3) prepared by co-precipitation were to explore their phosphate adsorption capacity from aqueous solution and the potential for soil phosphate interception. The results revealed that MABC composites contained more functional groups than MBC and showed a higher surface area than ABC. The surface of MABC contained dispersed MgAl2O4, Mg(OH)2, AlOOH and Al2O3 crystals that were associated with its enhanced maximum phosphate adsorption capacity (153.40 mg g-1). According to Langmuir model, the maximum adsorption capacity of MABC was 15.91, 1.85, and 93.54 times the capacity of MBC, ABC, and raw biochar (BC4), respectively. The addition of MABC in red soil could significantly slow down the release of soil phosphorus, and MABC also had a stronger phosphate interception capacity (59.89%) than other BCs. In summary, MABC exhibits superior phosphate adsorption and interception capacity, making it ideal for treatment and prevention of phosphorus-polluted water.


Assuntos
Fosfatos/química , Poluentes do Solo/química , Adsorção , Hidróxido de Alumínio , Óxido de Alumínio , Carvão Vegetal , Fósforo/química , Solo , Água
4.
Nat Commun ; 11(1): 2778, 2020 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-32513979

RESUMO

The use of photothermal agents (PTAs) in cancer photothermal therapy (PTT) has shown promising results in clinical studies. The rapid degradation of PTAs may address safety concerns but usually limits the photothermal stability required for efficacious treatment. Conversely, PTAs with high photothermal stability usually degrade slowly. The solutions that address the balance between the high photothermal stability and rapid degradation of PTAs are rare. Here, we report that the inherent Cu2+-capturing ability of black phosphorus (BP) can accelerate the degradation of BP, while also enhancing photothermal stability. The incorporation of Cu2+ into BP@Cu nanostructures further enables chemodynamic therapy (CDT)-enhanced PTT. Moreover, by employing 64Cu2+, positron emission tomography (PET) imaging can be achieved for in vivo real-time and quantitative tracking. Therefore, our study not only introduces an "ideal" PTA that bypasses the limitations of PTAs, but also provides the proof-of-concept application of BP-based materials in PET-guided, CDT-enhanced combination cancer therapy.


Assuntos
Cobre/química , Hipertermia Induzida , Neoplasias/terapia , Fósforo/química , Fototerapia , Tomografia por Emissão de Pósitrons , Animais , Morte Celular , Linhagem Celular Tumoral , Terapia Combinada , Cobre/farmacocinética , Humanos , Íons , Camundongos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Oligopeptídeos/química , Fósforo/farmacocinética , Polietilenoglicóis/química , Espectrofotometria Ultravioleta , Nanomedicina Teranóstica
5.
Chemosphere ; 259: 127402, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593819

RESUMO

Plastic waste has caused severe environmental problems. Some additives in plastics, like organophosphates, enter the environment with plastic waste, causing significant harm to plants and creatures. However, the primary method of recycling phosphorus-containing plastic, especially polycarbonate and acrylonitrile-butadiene-styrene copolymer (PC/ABS), is a mechanical method, which not only does not effectively separate plastics and organophosphates but also tends to cause polymer degradation during recycling. In order to overcome these problems, we proposed an efficient and sustainable approach to recycle of phosphorus-containing plastic. In this method, N, N-dimethylcyclohexylamine (DMCHA), a switchable hydrophilicity solvent (SHS), was used to react with and extract organophosphates in plastic, achieving the goal of complete separation of plastic and organophosphates. PC/ABS can be recovered by precipitation. Dissolved organophosphates can also be easily recovered due to the switching characteristics of SHS. Both of recovered materials were of high purity and were close to virgin materials. This technique is an easy and efficient approach to separate plastic and organophosphates, which has excellent application prospects in recycling phosphorus-containing plastic.


Assuntos
Fósforo/química , Plásticos/química , Reciclagem/métodos , Acrilonitrila , Butadienos , Interações Hidrofóbicas e Hidrofílicas , Cimento de Policarboxilato , Polímeros , Poliestirenos , Solventes
6.
Chemosphere ; 257: 127283, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32531492

RESUMO

The coming global phosphorus (P) crisis makes P recovery from wastewater become an inevitable choice. Hydroxyapatite (HAP) crystallization is an important approach for P recovery, but its requirements for high alkali and acid are unaffordable. Thus, a microbial electrolysis phosphorus-recovery cell (MEPRC) was developed to cut down the alkali cost via raising the wastewater pH (over 11) in the cathode chamber, and the acid cost via producing acid in the acid-production chamber. HAP was confirmed to be the final recovered products, and P recovery efficiency over 80% was achieved at 24-h operation. To optimize the P recovery performance of this system, the effects of the key factors including applied voltage, P initial concentration and Ca/P ration were investigated. High voltage could promote the rate of P recovery but had slight effect on the eventual recovery efficiency (elevated from 88.5 to 91.1%). High P initial concentration (15.0 mM) could slow down the pH elevation, contributing to the low P recovery efficiency (50.1%) within 24 h. However, prolonging the operation could break the buffering and obtain a satisfactory P recovery efficiency (87.2%) at 36 h. Besides, sufficient calcium ions were favorable to the P recovery. In addition, P recovery cost analyses of the MEPRC indicated that it might be a low-cost technology for P recovery. Moreover, the simultaneously produced acid could be used to neutralize the effluent after P recovery with high pH value. These results demonstrate the feasibility of MEPRC for cost-effective P recovery from wastewater.


Assuntos
Fósforo/análise , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Eletrodos , Eletrólise , Concentração de Íons de Hidrogênio , Fósforo/química , Água
7.
Chemosphere ; 256: 127138, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32450348

RESUMO

The present work investigates hazardous elements and nanomineralogical assemblages of phosphogypsum waste from an abandoned phosphate fertilizer industry located in Santa Catarina state (Brazil). Correlations between the chemical composition, nanominerals, and ultrafine particles are discussed. Multifaceted physical-geochemical study provided a careful understanding of the nanomineralogical assemblage of the phosphogypsum waste. The electron beam investigation revealed the presence of many hazardous elements in the ultrafine particles. Cr, Pb, Mn, Se, Sr, and Zr, among others, were found in individual ultrafine particles and nanominerals in all studied samples. Besides that, rare earth elements were found in different concentration ranges, being Ce, La, and Nd, the rare earth elements, found in the higher concentrations, above 900 mg kg-1. The data supplied by this article are important to characterize the phosphogypsum waste, assessing the potential hazard to the environment and human health, and also, provides information to enable the designing of alternatives to manage this waste.


Assuntos
Sulfato de Cálcio/química , Monitoramento Ambiental , Fertilizantes/análise , Metais Pesados/análise , Metais Terras Raras/análise , Fósforo/química , Brasil , Humanos , Material Particulado/análise , Fosfatos/análise
8.
Chemosphere ; 256: 126968, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32428738

RESUMO

The recycling of nutrients from wastewater and their recovery in the form of valuable products is an effective strategy to accelerate the circular economy concept. Phosphorus recovery from wastewater by struvite crystallization (MgNH4PO4·6H2O) is one of the most applied techniques to compensate for the increasing demand and to slow down the depletion rate of phosphate rocks. Using low-cost magnesium sources, such as seawater, improves the financial sustainability of struvite production. In this study, the potential of seawater for struvite crystallization versus the commonly used magnesium source, MgCl2, was tested by crystal growth and kinetic experiments. The impact of ammonium concentration, magnesium concentration and pH on the growth kinetics of struvite in synthetic and real reject water were studied. The results showed that simultaneous precipitation of calcium phosphate was insignificant when using seawater, while presence of struvite seeds diminished it further. Among the supersaturation regulators, pH had the most significant effect on the struvite growth with both MgCl2 and seawater, while high N:P molar ratios further improved the struvite crystal growth by seawater. The N:P molar ratios higher than 6 and Mg:P molar ratios higher than 0.2 are recommended to improve the crystal growth kinetics. It was concluded that seawater is a promising alternative magnesium source and the control of supersaturation regulators (i.e., Mg:P, N:P and pH) is an effective strategy to control the reaction kinetics and product properties.


Assuntos
Modelos Químicos , Água do Mar/química , Estruvita/química , Fosfatos de Cálcio , Cristalização , Cinética , Magnésio/química , Cloreto de Magnésio/química , Compostos de Magnésio/química , Minerais , Fosfatos/química , Fósforo/química , Reciclagem , Águas Residuárias/química
9.
Sci Total Environ ; 734: 139284, 2020 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-32450400

RESUMO

This study aims to investigate the effect of anaerobic digestion (AD) on P species and how the different species are distributed in the digestate and digestate fractions, i.e. liquid and solid fractions. To do so, six full scale AD plants were used in this work and representative biomass samples were collected for investigation. P fractionation proceeded by adopting fractionation protocols consisting in step-by-step extraction with different solvents, (i.e. NaHCO3, HCl and NaOH-EDTA). Subsequently P species in the different fractions were identified by using 31PNMR. On average, AD did not substantially affect P speciation that depended on the P-fraction content of feeds. A high NaHCO3 fraction content in the ingestate determined, also, a high content of this fraction in the digestate, with consequently lower contents of both P-HCl and P-NaOH-EDTA, i.e. digestate P-fraction contents represented an inheritance of P speciation in the ingestate. A feed effect was observed in single plants. Highest pig/cow slurry content in the feeds seemed to decrease readily soluble P (extracted with NaHCO3) content and increased P associated with both organic matter and amorphous Fe/Al in the digestate. Again, using a large amount of digestate in the feed increased P-soluble content in the digestate. 31P NMR analyses revealed that inorganic P compounds dominated the spectra of all biomasses and fractions, with orthophosphate as the predominant species. When present, organic phosphorus compounds were typically represented by monophosphate esters, DNA and phospholipids, with a predominance of monophosphate esters.


Assuntos
Fósforo/química , Anaerobiose , Animais , Biomassa , Bovinos , Feminino , Suínos
10.
Int J Nanomedicine ; 15: 3071-3085, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32431502

RESUMO

Purpose: Recently, two-dimensional (2D) nanomaterials are gaining tremendous attention as novel antibacterial platforms to combat against continuously evolving antimicrobial resistance levels. Among the family of 2D nanomaterials, black phosphorus (BP) nanosheets have demonstrated promising potential for biomedical applications. However, there is a need to gain nanoscale insights of the antibacterial activity of BP nanosheets which lies at the center of technical challenges. Methods: Ultra-large BP nanosheets were synthesized by liquid-exfoliation method in the eco-friendly deoxygenated water. Synthesized BP nanosheets were characterized by TEM, AFM, and Raman spectroscopy techniques and their chemical stability was evaluated by EDS and EELS elemental analysis. The antibacterial activity of BP nanosheets was evaluated at nanoscale by the ultramicrotome TEM technique. Further, HAADF-STEM image and EDS elemental line map of the damaged bacterium were utilized to analyze the presence of diagnostic ions. Supportive SEM and ATR-FTIR studies were carried out to confirm the bacterial cell wall damage. In vitro colony counting method was utilized to evaluate the antibacterial performance of ultra-large BP nanosheets. Results: Elemental EELS and EDS analysis of BP nanosheets stored in deoxygenated water confirmed the absence of oxygen peak. TEM studies indicate the various events of bacterial cell damage with the lost cellular metabolism and structural integrity. Colony counting test results show that as-synthesized BP nanosheets (100 µg/mL) can kill ~95% bacteria within 12 hours. Conclusion: TEM studies demonstrate the various events of E. coli membrane damage and the loss of structural integrity. These events include the BP nanosheets interaction with the bacterial cell wall, cytoplasmic leakage, detachment of cytoplasm from the cell membrane, reduced density of lipid bilayer and agglomerated DNA structure. The EDS elemental line mapping of the damaged bacterium confirms the disrupted cell membrane permeability and the lost cellular metabolism. SEM micrographs and ATR-FTIR supportive results confirm the bacterial cell wall damage.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Nanoestruturas/química , Fósforo/química , Parede Celular/efeitos dos fármacos , Parede Celular/ultraestrutura , Escherichia coli/ultraestrutura , Testes de Sensibilidade Microbiana , Microscopia de Força Atômica , Microscopia Eletrônica de Transmissão , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Água/química
11.
Int J Nanomedicine ; 15: 2045-2058, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32273701

RESUMO

Bone regeneration remains a great clinical challenge. Two-dimensional materials, especially graphene and its derivative graphene oxide, have been widely used for bone regeneration. Since its discovery in 2014, black phosphorus (BP) nanomaterials including BP nanosheets and BP quantum dots have attracted considerable scientific attention and are considered as prospective graphene substitutes. BP nanomaterials exhibit numerous advantages such as excellent optical and mechanical properties, electrical conductivity, excellent biocompatibility, and good biodegradation, all of which make them particularly attractive in biomedicine. In this review, we comprehensively summarize recent advances of BP-based nanomaterials in bone regeneration. The advantages are reviewed, the different synthesis methods of BP are summarized, and the applications to promote bone regeneration are highlighted. Finally, the existing challenges and perspectives of BP in bone regeneration are briefly discussed.


Assuntos
Regeneração Óssea/fisiologia , Nanoestruturas/química , Nanoestruturas/uso terapêutico , Fósforo/química , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/uso terapêutico , Regeneração Óssea/efeitos dos fármacos , Grafite/química , Humanos , Pontos Quânticos/química
12.
PLoS One ; 15(3): e0230192, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32226036

RESUMO

While movement patterns of grazing ungulates are strongly dependent on forage quality their use of nutrient hotspots such as termite mounds or grazing lawns has rarely been quantified, especially in savanna ecosystems where soil-nutrient quality is low. Additionally, few experiments have been conducted to determine the role of termite mound- and grazing lawn-derived soils in improving forage quality in the field. We studied wild ungulate grazing activities around ten termite mounds, six grazing lawns and their respective control sites in a Miombo system of Issa Valley, western Tanzania, in the same system. We used indirect observations (i.e., dung, tracks) to identify seasonal and spatial variations in habitat use of various wild mammalian grazers. Grazer visitation rates were nine and three times higher on termite mounds and grazing lawns, respectively, compared to control sites. During the rainy season, termite mounds were more frequently used than grazing lawns while the latter were used more often during the dry season. In an additional pot experiment with soils derived from different areas, we found that Cynodon dactylon in termite mound-derived soils had twice as high Nitrogen and Phosphorous contents and biomass compared to grasses planted in grazing lawn soils and control site soils. We highlight that both termite mounds and grazing lawns play a significant role in influencing seasonal nutrient dynamics, forage nutrient quality, habitat selectivity, and, hence, grazing activities and movement patterns of wild ungulate grazers in savannas. We conclude that termite mounds and grazing lawns are important for habitat heterogeneity in otherwise nutrient-poor savanna systems.


Assuntos
Cynodon/química , Nutrientes/química , Poaceae/química , Animais , Biomassa , Ecossistema , Comportamento Alimentar/fisiologia , Pradaria , Isópteros/química , Mamíferos , Nitrogênio/química , Fósforo/química , Plantas/química , Estações do Ano , Solo/química , Tanzânia
13.
Environ Geochem Health ; 42(10): 3231-3246, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32323172

RESUMO

Controlled drainage is considered as a soil management tool to improve water supply to crops and reduce nutrient losses from fields; however, its closure may affect phosphorus (P) mobilization in soil. To assess the P mobilization potential, three soil profiles with redoximorphic features were selected along a slight hill in Northern Germany. Soil samples from three depths of each profile were characterized for basic properties, total element content, oxalate- and dithionite-extractable pedogenic Al, Fe and Mn (hydr)oxides, P pools (sequential extraction), P species [P K-edge X-ray absorption near-edge structure (XANES) spectroscopy] and P sorption behavior. In topsoil (~ 10 cm depth), labile P (H2O-P + resin-P + NaHCO3-P) accounted for 26-32% of total P (Pt). Phosphorus K-edge XANES revealed that up to 49% of Pt was bound to Al and/or Fe (hydr)oxides, but sequential fractionation indicated that > 30% of this P was occluded within sesquioxide aggregates. A low binding capacity for P was demonstrated by P sorption capacity and low Kf coefficients (20-33 [Formula: see text]) of the Freundlich equation. In the subsoil layers (~ 30 and ~ 65 cm depth), higher proportions of Al- and Fe-bound P along with other characteristics suggested that all profiles might be prone to P mobilization/leaching risk under reducing conditions even if the degree of P saturation (DPS) of a profile under oxic conditions was < 25%. The results suggest that a closure of the controlled drainage may pose a risk of increased P mobilization, but this needs to be compared with the risk of uncontrolled drainage and P losses to avoid P leaching into the aquatic ecosystem.


Assuntos
Fósforo/química , Solo/química , Adsorção , Agricultura , Alemanha , Oxirredução , Solo/classificação
14.
Chemistry ; 26(26): 5903-5910, 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32142179

RESUMO

First-in-class CuII and AuIII metaled phosphorus dendrons were synthesized and showed significant antiproliferative activity against several aggressive breast cancer cell lines. The data suggest that the cytotoxicity increases with reducing length of the alkyl chains, whereas the replacement of CuII with AuIII considerably increases the antiproliferative activity of metaled phosphorus dendrons. Very interestingly, we found that the cell death pathway is related to the nature of the metal complexed by the plain dendrons. CuII metaled dendrons showed a potent caspase-independent cell death pathway, whereas AuIII metaled dendrons displayed a caspase-dependent apoptotic pathway. The complexation of plain dendrons with AuIII increased the cellular lethality versus dendrons with CuII and promoted the translocation of Bax into the mitochondria and the release of Cytochrome C (Cyto C).


Assuntos
Citocromos c/metabolismo , Dendrímeros/metabolismo , Metais/química , Mitocôndrias/química , Fósforo/química , Apoptose , Morte Celular , Citocromos c/química , Dendrímeros/química , Humanos , Células MCF-7 , Metais/metabolismo , Mitocôndrias/metabolismo , Estrutura Molecular , Fósforo/metabolismo
15.
Ecotoxicol Environ Saf ; 194: 110384, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32126412

RESUMO

Electrolytic manganese residue (EMR) contains a large amount of NH4+-N and Mn2+ and can negatively impact the environment. A stabilization treatment of soluble contaminants in the EMR is necessary for its reuse and safe stacking. This study presents experimental results for the stabilization of NH4+-N and Mn2+ in the EMR using phosphogypsum leachate as a low-cost phosphate source and MgO/CaO (PLMC) process. The results demonstrated that the stabilization efficiency of NH4+-N and Mn2+ was 93.65% and 99.99%, respectively, under the following conditions: a phosphogypsum leachate dose of 1.5 mL g-1, an added MgO dose of 0.036 g g-1, an added CaO dose of 0.1 g g-1 and a reaction time of 2 h. The stabilization effect of the PLMC process was higher and more cost effective than that of using Na3PO4·12H2O and MgO/CaO. The concentration of NH4+-N and Mn2+ in the leaching liquor decreased to 80 mg L-1 and 0.5 mg L-1, respectively, after the stabilization under the optimum conditions. The stabilization characteristics indicated that NH4+-N was stabilized to form NH4MgPO4·6H2O (struvite) and that Mn2+ was stabilized to form Mn5(PO4)2(OH)4, Mn3(PO4)2·3H2O and Mn(OH)2. PO43--P, F-, and heavy metal ions of the phosphogypsum leachate were removed from the leaching liquor and stabilized in the treated EMR.


Assuntos
Compostos de Cálcio/química , Sulfato de Cálcio/química , Óxido de Magnésio/química , Manganês/análise , Óxidos/química , Fósforo/química , Amônia/análise , Amônia/química , Eletrólise , Eletrólitos , Poluentes Ambientais/análise , Poluentes Ambientais/química , Resíduos Industriais/análise , Manganês/química , Solubilidade , Estruvita/análise , Estruvita/química
16.
PLoS One ; 15(3): e0230178, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32187213

RESUMO

The Olsen phosphorus (Olsen-P) concentration of soil is generally a good indicator for estimating the bioavailability of P and environmental risk in soils. To maintain soil Olsen-P at adequate levels for crop growth and environmental sustainability, the relationship between soil Olsen-P and the P budget (the P input minus the output) as well as the variations of soil Olsen-P and P budget were investigated from three long-term (22 years) experiments in China. Five treatments were selected: (1) unfertilized control (CK); (2) nitrogen and potassium (NK); (3) nitrogen, phosphorous, and potassium (NPK); (4) nitrogen, phosphorous, potassium and straw; (5) nitrogen, phosphorous, potassium and manure. The results showed that without P fertilizers (CK, NK), there was a soil P deficit of 75-640 kg ha-1, and the lowest P deficit (mean of CK and NK) was in Eutric Cambisol. Soil Olsen-P decreased by 0.11-0.39 mg kg-1 year-1 in the order of Luvic Phaeozems > Eutric Cambisol > Calcaric Cambisol. Soil Olsen-P and the P deficit had a significantly (P<0.01) positive linear relationship. For every 100 kg of P ha-1 of deficit, soil Olsen-P decreased by 0.44-9.19 mg kg-1 in the order of Eutric Cambisol > Luvic Phaeozems > Calcaric Cambisol. Under the P fertilizer treatments (NPK, NPKS, and NPKM), soil Olsen-P showed an obvious surplus (except the NPK and NPKS in Luvic Phaeozems) of 122-2190 kg ha-1, and the largest P surplus was found under the NPKM treatment at each site. The relation between soil Olsen-P and the experimental years could be simulated using quadratic equation of one unknown in Calcaric Cambisol for the lower P input after 14 years of fertilization. And soil Olsen-P increased by 1.30-7.69 mg kg-1 year-1 in the order of Luvic Phaeozems > Eutric Cambisol. The relation between soil Olsen-P and the P surplus could be simulated by a simple linear equation except under NPK and NPKS in Luvic Phaeozems. With 100 kg ha-1 P surplus, soil Olsen-P increased by 3.24-7.27 mg kg-1 in the order of Calcaric Cambisol (6.42 mg kg-1) > Eutric Cambisol (3.24 mg kg-1). In addition, the change in soil Olsen-P with a 100 kg P ha-1 surplus (soil Olsen-P efficiency) was affected by the soil organic matter (SOM), pH, and CaCO3 content, etc. In the practice of fertilization, it's not necessary to increase the amount of P fertilizers, farmers should take measure to solve the local problem, for adjust the soil pH of Eutric Cambisol and Calcaric Cambisol, and apply more nitrogen in Luvic Phaeozems. In the area of serious soil P surplus, it is encouraged to stop applying P fertilizers for a few years to take advantage of soil accumulated P and make the high Olsen-P content decrease to a reasonable level.


Assuntos
Fósforo/química , Potássio/química , Agricultura/métodos , China , Produtos Agrícolas/química , Fazendeiros , Fertilizantes , Esterco/análise , Nitrogênio/química , Solo
17.
Chemosphere ; 248: 125979, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32028158

RESUMO

In China, the amount of phosphogypsum (PG) has exceeded 250 million tons with more than 55 million tons of growth rates each year. As the micro constituent, fluorine and phosphorus restrict the resourceful disposal of PG. This paper focused on chemical looping gasification (CLG) which used PG as an oxygen carrier, systematically investigated the gasification performance and chemical behavior of fluorine and phosphorus contained in PG during CLG process. Main conclusions are as follows. The main pollutant of chemical looping gasification process was HF, which was transformed from NaF. Phosphorus transformed from water-soluble phosphorus (Ca(H2PO4)2, Ca(HPO4)) into insoluble Ca3(PO4)2.20 reducing-oxidizing cycles were investigated, and a less and less fluorine content in oxygen carrier was found because its phase transformation from solid NaF to gaseous HF, and the phosphorus content in oxygen carrier changed slightly under the current conditions. The Ca3(PO4)2 particle layers existed in both the middle of the reduced solid particles and the middle of the cycled oxygen carrier particles, confirmed to actually act as a glue between the particles. Furthermore, transformation routes of fluorine and phosphorus during the CLG process were discussed and the generation of syngas in CLG process needed to be purified.


Assuntos
Sulfato de Cálcio/química , Flúor/química , Fósforo/química , China , Fluoretos , Gases , Oxigênio/química , Água
18.
Chemosphere ; 248: 126026, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32006839

RESUMO

Phosphorus-containing flame retardants (PFRs) have been frequently detected in various environmental samples at relatively high concentrations and are considered emerging environmental pollutants. However, their biological effects and the underlying mechanism remain unclear, especially alkyl-PFRs. In this study, a battery of in vitro bioassays was conducted to analyze the cytotoxicity, oxidative stress, mitochondrial impairment, DNA damage and the involved molecular mechanisms of several selected alkyl-PFRs. Results showed that alkyl-PFRs induced structural related toxicity, where alkyl-PFRs with higher logKow values induced higher cytotoxicity. Long-chain alkyl-PFRs caused mitochondrial and DNA damage, resulting from intracellular reactive oxygen species (ROS) and mitochondrial superoxide overproduction; while short-chain alkyl-PFRs displayed adverse outcomes by significantly impairing mitochondria without obvious ROS generation. In addition, alkyl-PFRs caused DNA damage-induced cell cycle arrest, as determined by flow cytometry, and transcriptionally upregulated key transcription factors in p53/p21-mediated cell cycle pathways. Moreover, compared to the control condition, triisobutyl phosphate and trimethyl phosphate exposure increased the sub-G1 apoptotic peak and upregulated the p53/bax apoptosis pathway, indicating potential cell apoptosis at the cellular and molecular levels. These results provide insight into PFR toxicity and the involved mode of action and indicate the mitochondria is an important target for some alkyl-PFRs.


Assuntos
Retardadores de Chama/toxicidade , Pontos de Checagem da Fase G1 do Ciclo Celular/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Células A549 , Dano ao DNA , Poluentes Ambientais/toxicidade , Humanos , Mitocôndrias/efeitos dos fármacos , Organofosfatos/toxicidade , Fósforo/química , Testes de Toxicidade , Fatores de Transcrição/genética
19.
Chemosphere ; 247: 125847, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32069709

RESUMO

The effective removal and recovery of phosphorus from aquatic environments are highly important for successful eutrophication control and phosphorus recycling. Herein, we prepared biochar containing MgO nanoparticles (MgO-biochar) by fast pyrolysis of MgCl2-impregnated corn stalks, probed its phosphate adsorption performance. Through the fast pyrolysis, the MgCl2 promoted the formation of micropores and mesoporous, and decomposed into MgO nanoparticles with the size smaller than 100 nm. The adsorption experiments showed that the adsorption property increased with the increase of Mg content, and had a strong correlation with the external surface area. And the phosphate adsorption was well described by the Langmuir-Freundlich model (maximum adsorption capacity was determined as 60.95 mg P/g). Kinetic analysis and characterization analysis of MgO-biochar for different adsorption time indicated that phosphate adsorption onto MgO-biochar was mainly controlled by rapid binding to the external surface (about 75% of the equilibrium adsorption amount), and the uptake rate was limited by the slow diffusion of phosphate into the biochar interior (about 25% of the equilibrium adsorption amount). The results suggested that the synthesized MgO-biochar with enough MgO active site dispersed on a higher external surface can be used as a potential adsorbent for phosphate removal and recovery from aqueous solution.


Assuntos
Carvão Vegetal/síntese química , Óxido de Magnésio/química , Fósforo/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cinética , Nanopartículas/química , Fosfatos/química , Fósforo/química , Reciclagem , Água , Poluentes Químicos da Água/análise
20.
Environ Pollut ; 261: 114223, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32109821

RESUMO

Iron oxide-biochar composites have been widely used in removal of phosphate from water, however, their effects on phosphorus retention and decrease leaching are unclear in saline-alkaline soils. We utilized rice straw-derived biochar modified with ferrous chloride (Fe(II)) and ferric chloride (Fe(III)) to study the potential mechanisms of phosphorus retention and leaching under field conditions. Results showed that the Fe(II) biochar exhibited superior phosphate adsorption capacity (39.2 mg g-1) over the unmodified. In addition, Fe(III) biochar was relatively insensitive to pH and competed anions. This might be due to iron in Fe(II) biochar that exists primarily in an amorphous state as FeOOH, which enhanced its ability to adsorb phosphate because it has high isoelectric points. Crystals of Fe2PO5 and (PO3)3 were formed in the Fe(II) and Fe(III) biochars, respectively. Electrostatic attraction and ligand exchange contributed to phosphate adsorption. In the column leaching experiments, all treatments were found to significantly increase the phosphorus content in 0-20 cm soil compared to Control, especially with Fe(II) biochar amendment. Fe(II) biochar decreased leaching by 86.4%. In the field experiments, Fe(II) and Fe(III) biochar increased the available phosphorus by 78.6% and 90.3%, respectively. Overall, application of iron modified biochar to saline-alkaline soils promoted phosphorus adsorption and decreased leaching.


Assuntos
Carvão Vegetal , Ferro , Fósforo , Poluentes do Solo , Solo , Adsorção , Carvão Vegetal/química , Compostos Férricos/química , Ferro/química , Fósforo/química , Solo/química
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