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1.
Molecules ; 26(4)2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33672045

RESUMEN

Hydrochar is a carbon-based material that can be used as soil amendment. Since the physical-chemical properties of hydrochar are mainly assigned to process parameters, we aimed at evaluating the organic fraction of different hydrochars through 13C-NMR and off-line TMAH-GC/MS. Four hydrochars produced with sugarcane bagasse, vinasse and sulfuric or phosphoric acids were analyzed to elucidate the main molecular features. Germination and initial growth of maize seedlings were assessed using hydrochar water-soluble fraction to evaluate their potential use as growth promoters. The hydrochars prepared with phosphoric acid showed larger amounts of bioavailable lignin-derived structures. Although no differences were shown about the percentage of maize seeds germination, the hydrochar produced with phosphoric acid promoted a better seedling growth. For this sample, the greatest relative percentage of benzene derivatives and phenolic compounds were associated to hormone-like effects, responsible for stimulating shoot and root elongation. The reactions parameters proved to be determinant for the organic composition of hydrochar, exerting a strict influence on molecular features and plant growth response.


Asunto(s)
Espectroscopía de Resonancia Magnética con Carbono-13 , Carbón Orgánico/química , Carbón Orgánico/farmacología , Cromatografía de Gases y Espectrometría de Masas , Desarrollo de la Planta/efectos de los fármacos , Compuestos de Amonio Cuaternario/química , Agua/química , Bioensayo , Raíces de Plantas/anatomía & histología , Raíces de Plantas/efectos de los fármacos , Brotes de la Planta/anatomía & histología , Brotes de la Planta/efectos de los fármacos , Semillas/efectos de los fármacos , Zea mays/efectos de los fármacos , Zea mays/crecimiento & desarrollo
2.
Molecules ; 26(4)2021 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-33670660

RESUMEN

Water decontamination still remains a major challenge to some developing countries not having centralized wastewater systems. Therefore, this study presents the optimization of photocatalytic degradation of Basic Blue 41 dye in an aqueous medium by an activated carbon (AC)-TiO2 photocatalyst under UV irradiation. The mesoporous AC-TiO2 synthesized by a sonication method was characterized by X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy for crystal phase identification and molecular bond structures, respectively. The efficiency of the AC-TiO2 was evaluated as a function of three input variables viz. catalyst load (2-4 g), reaction time (15-45 min) and pH (6-9) by using Box-Behnken design (BBD) adapted from response surface methodology. Using color and turbidity removal as responses, a 17 run experiment matrix was generated by the BBD to investigate the interaction effects of the three aforementioned input factors. From the results, a reduced quadratic model was generated, which showed good predictability of results agreeable to the experimental data. The analysis of variance (ANOVA), signposted the selected models for color and turbidity, was highly significant (p < 0.05) with coefficients of determination (R2) values of 0.972 and 0.988, respectively. The catalyst load was found as the most significant factor with a high antagonistic impact on the process, whereas the interactive effect of reaction time and pH affected the process positively. At optimal conditions of catalyst load (2.6 g), reaction time (45 min), and pH (6); the desirability of 96% was obtained by a numerical optimization approach representing turbidity removal of 93% and color of 96%.


Asunto(s)
Compuestos Azo/efectos de la radiación , Benzotiazoles/efectos de la radiación , Carbón Orgánico/química , Fotólisis/efectos de la radiación , Titanio/química , Rayos Ultravioleta , Análisis de Varianza , Catálisis/efectos de la radiación , Color , Concentración de Iones de Hidrógeno , Cinética , Nefelometría y Turbidimetría , Espectroscopía Infrarroja por Transformada de Fourier , Difracción de Rayos X
3.
Ecotoxicol Environ Saf ; 213: 112075, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33636468

RESUMEN

Biochars were studied for their impacts on the dissipation and vegetable uptake of polycyclic aromatic hydrocarbons (PAHs) in an agricultural soil. The health risks of PAHs taken up by vegetables were assessed by growing Chinese cabbage in both unamended soil and biochar-amended soils. In the unamended soil, the total 16 PAHs (Σ16PAHs) content decreased by 77.38% after planting the vegetable. The dissipation percentages of low-molecular-weight PAHs (LMW-PAHs), medium-molecular-weight PAHs (MMW-PAHs), and high-molecular-weight PAHs (HMW-PAHs) were 82.37%, 72.65%, and 68.63%, respectively. A significant negative correlation was determined between the dissipation percentages of PAHs in soil and the logKow of PAHs (p < 0.01), indicating that the affinity of PAHs for soil particles was one of an important limiting factors on the dissipation of PAHs. The uptake of PAHs by plant was significantly reduced with the increase in the molecular weight of the PAHs (76.55% for LWM-PAHs, 17.13% for MMW-PAHs, and 6.05% for HMW-PAHs). Addition of biochars to the soil decreased the dissipation of Σ16PAHs (73.59-77.01%), mostly due to a decrease in the dissipation of LMW-PAHs and MMW-PAHs. This finding was due to the immobilization of LMW-PAHs and MMW-PAHs within the biochar micropores. A marked reduction of Proteobacteria in biochar-amended soils also resulted in the decreased biodegradation of PAHs. Four of six biochars significantly increased the concentrations of Σ16PAHs in plant by 30.10-74.22%. Generally, biochars significantly increased the uptake of LMW-PAHs by plant but had little influence on the plant uptake of MMW-PAHs and HMW-PAHs. Three of six biochars notably increased the incremental lifetime cancer risk values based on the exposure of PAHs by vegetable consumption.


Asunto(s)
Biodegradación Ambiental , Hidrocarburos Policíclicos Aromáticos/análisis , Contaminantes del Suelo/análisis , Agricultura , Carbón Orgánico/química , Suelo , Verduras/metabolismo
4.
J Chromatogr A ; 1639: 461932, 2021 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-33535117

RESUMEN

Position-specific isotope analysis by Nuclear Magnetic Resonance spectrometry was employed to study the 13C intramolecular isotopic fractionation associated with the migration of organic substrates through different stationary phases chromatography columns. Liquid chromatography is often used to isolate compounds prior to their isotope analysis and this purification step potentially alters the isotopic composition of target compounds introducing a bias in the later measured data. Moreover, results from liquid chromatography can yield the sorption parameters needed in reactive transport models that predict the transport and fate of organic contaminants to in the environment. The aim of this study was to use intramolecular isotope analysis to study both 13C and 15N isotope effects associated with the elution of paracetamol (acetaminophen) through different stationary phases and to compare them to effects observed previously for vanillin. Results showed very different intramolecular isotope fractionation profiles depending on the chemical structure of the stationary phase. The data also demonstrate that both the amplitude and the distribution of measured isotope effects depend on the nature of the non-covalent interactions involved in the migration process. Results provided by theoretical calculation performed during this study also confirmed the direct link between observed intramolecular isotope fractionation and the nature of involved intermolecular interactions. It is concluded that the nature of the stationary phase through which the substrate passes has a major impact on the intramolecular isotopic composition of organic compounds isolated by chromatography methods..


Asunto(s)
Acetaminofén/análisis , Isótopos de Carbono/química , Cromatografía Liquida/métodos , Isótopos de Nitrógeno/química , Espectroscopía de Resonancia Magnética con Carbono-13 , Celulosa/química , Carbón Orgánico/química , Fraccionamiento Químico , Reproducibilidad de los Resultados , Gel de Sílice/química , Solventes/química
5.
Ecotoxicol Environ Saf ; 208: 111690, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396022

RESUMEN

The purpose of this study was to produce rendering animal carcass residue char (RACR-C) by pyrolyzing the solid residues of low-recyclable rendered pig carcasses and to evaluate their cadmium (Cd) adsorption characteristics and mechanisms. As the pyrolysis temperature increased, the inorganic content of RACR-C increased, while the carbon content decreased. In particular, the surface structure and chemistry of RACR-Cs prepared at different pyrolysis temperatures were well described by SEM-EDS, XRD, XRF, TGA, and FTIR. The Cd adsorption characteristics of RACR-C were in good agreement with the Langmuir isotherm and pseudo-second-order models, and the Cd adsorption capacities of RACR-Cs prepared at various pyrolysis temperatures were in the order of RACR-C500 (73.5 mg/g)> RACR-C600 (53.8 mg/g)> RACR-C400 (41.5 mg/g) " RACR-C250 (15.9 mg/g). The intraparticle diffusion model suggested that the adsorption of Cd by RACR-C is greatly influenced by internal diffusion as well as external boundary. Since the Cd adsorption capacity of RACR-C is greatly influenced by the initial dosage, pH, and co-existing metals, it is necessary to manage these influencing factors when treating wastewater containing heavy metals. Our results suggest that Cd adsorption by RACR-C is a complex adsorption phenomenon by various mechanisms such as adsorption by functional group (CË­C and C-O), precipitation of Cd-P and ion exchange reaction by exchangeable cation occurring rather than by a single specific mechanism.


Asunto(s)
Huesos/química , Cadmio/análisis , Carbón Orgánico/química , Pirólisis , Residuos/análisis , Contaminantes Químicos del Agua/análisis , Adsorción , Animales , Difusión , Intercambio Iónico , Proteínas/química , Porcinos , Temperatura , Aguas Residuales/química
6.
Ecotoxicol Environ Saf ; 208: 111675, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396007

RESUMEN

Metal bioavailability controls its behaviors in soil-plant system, especially involved in biochar amendment. This study compared a rhizospheric pore-water extraction against a BCR sequential extraction method to understand cadmium (Cd) bioavailability in two typical Chinese soils. Soils were spiked with five levels of Cd (CdCl2) and remediated with 3% corn-straw derived biochar. After 60 days of lettuce growth, Cd accumulation and enzyme activities in tissues were analyzed. Results showed that biochar increased soil properties (pH, CEC and SOM) compared to un-amended soils, but decreased contents of bioavailable Cd in soil pore-water (Cdpore-water) and BCR extracted Cd (CdFi+Fii). Contents of Cdpore-water were lower in yellow-brown soils than that in red soils. Pearson analysis showed that bioavailable Cd is negatively correlated with soil pH and CEC (p < 0.05). Cd accumulation in lettuce roots and leaves both were decreased by biochar addition, and the established linear equations proved that soil Cdpore-water is the best predictor for Cd accumulation in lettuce roots (r2 = 0.964) and in leaves (r2 = 0.953), followed by CdFi+Fii. Transfer factor (TF) values of Cd from roots to leaves were lower than 1, and slightly better correlated with soil Cdpore-water (r = -0.674, p < 0.01) than CdFi+Fii (r = -0.615, p < 0.01). Aggregated boosted tree (ABT) analyses indicated that soil properties together with Cdpore-water contribute more than 50% to root enzyme activities. Collectively, soil Cdpore-water is a promising predictor of Cd bioavailability, accumulation and toxicity in soil-plant system with biochar addition.


Asunto(s)
Bioacumulación/efectos de los fármacos , Cadmio/toxicidad , Carbón Orgánico/química , Lechuga/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Disponibilidad Biológica , Transporte Biológico , Cadmio/metabolismo , Lechuga/metabolismo , Modelos Teóricos , Hojas de la Planta/efectos de los fármacos , Hojas de la Planta/metabolismo , Raíces de Plantas/efectos de los fármacos , Raíces de Plantas/metabolismo , Tallos de la Planta/química , Rizosfera , Suelo/química , Contaminantes del Suelo/metabolismo , Agua/química , Zea mays/química
7.
Ecotoxicol Environ Saf ; 208: 111723, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396054

RESUMEN

Combining biochar (BR) with other immobilizing amendments has additive effects on Pb immobilization and been recognized to be effective for the restoration of Pb polluted soils. However, the impacts of different proportions between BR and a highly efficient Pb immobilizing agent called "magnesium potassium phosphate cement (MC)" have never been earlier investigated. This work aimed to investigate the consequences of BR and MC alone and their mixtures of 25:75, 50:50, and 75:25 ratios on Pb bioavailability, Pb immobilization index (Pb-IMMi), and enzymatic activities in Pb polluted soil. Furthermore, amendments effects on Pb distribution in spinach, growth, antioxidant capacity, biochemical, and nutritional spectrum were also investigated. We found that MC alone performed well to immobilize Pb in soil and reducing its distribution in shoots, but was less efficient to improve soil enzymatic activities and plant attributes. Conversely, the application of BR alone stimulated soil enzymatic activities, plant growth, and quality but was less effective to immobilize Pb in soil and reducing shoot Pb concentrations. The combinations of BR and MC of various ratios showed variable results. Interestingly, the most promising outcomes were obtained with BR50%+MC50% treatment which resulted in enhanced Pb-IMMi (73%), activities of soil enzymes, plant growth and quality, and antioxidant capacity, compared to control. Likewise, significant reductions in Pb concentrations in shoots (85%), roots (78%), extractable Pb (73%) were also obtained with BR50%+MC50% treatment, compared to control. Such outcomes point towards a cost-effective approach for reducing Pb uptake by the plants via using MC and BR at a 50:50 ratio.


Asunto(s)
Carbón Orgánico/química , Plomo/farmacocinética , Compuestos de Magnesio/química , Fosfatos/química , Compuestos de Potasio/química , Contaminantes del Suelo/farmacocinética , Spinacia oleracea/metabolismo , Disponibilidad Biológica , Materiales de Construcción , Restauración y Remediación Ambiental , Plomo/análisis , Nyctaginaceae/química , Suelo/química , Contaminantes del Suelo/análisis , Spinacia oleracea/crecimiento & desarrollo
8.
Ecotoxicol Environ Saf ; 208: 111756, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396079

RESUMEN

To deeply assess the feasibility of sewage sludge-based biochars for use in soil applications, this review compared sewage sludge-based biochars (SSBBs) with lignocellulose-based biochars (LCBBs) in terms of their pyrolysis processes, various fractions and potential soil applications. Based on the reviewed literature, significant differences between the components of SSBB and LCBB result in different pyrolysis behavior. In terms of the fractions of biochars, obvious differences were confirmed to exist in the carbon content, surface functional groups, types of ash fractions and contents of potential toxic elements (PTEs). However, a clear influence of the feedstock on labile carbon and polycyclic aromatic hydrocarbons (PAHs) was not observed in the current research. These differences determined subsequent discrepancies in the soil application potential and corresponding mechanisms. The major challenges facing biochar application in soils and corresponding recommendations for future research were also addressed. LCBBs promote carbon sequestration, heavy metal retention and organic matter immobilization. The application of SSBBs is a promising approach to improve soil phosphorus fertility, immobilize heavy metals and provide available carbon sources for soil microbes to stimulate microbial biomass. The present review provides guidance information for selecting appropriate types of biochars to address targeted soil issues.


Asunto(s)
Carbón Orgánico/química , Restauración y Remediación Ambiental/métodos , Metales Pesados/química , Pirólisis , Contaminantes del Suelo/química , Biomasa , Carbono , Lignina , Metales Pesados/análisis , Hidrocarburos Policíclicos Aromáticos , Aguas del Alcantarillado , Suelo , Contaminantes del Suelo/análisis
9.
Ecotoxicol Environ Saf ; 208: 111552, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396093

RESUMEN

A novel material that nano zero valent iron (nZVI) loaded on biochar with stable starch stabilization (nZVI/SS/BC) was synthesized and used for the removal of hexavalent chromium [Cr(VI)] in simulated wastewater. It was indicated that as the pyrolysis temperature of rice straw increased, the removal rate of Cr(VI) by nZVI/SS/BC first increased and then decreased. nZVI/SS/BC made from biochar pyrolyzed at 600 °C (nZVI/SS/BC600) had the highest removal efficiency and was suitable for a wide pH range (pH 2.1-10.0). The results showed that 99.67% of Cr(VI) was removed by nZVI/SS/BC600, an increase of 45.93% compared to the control group, which did not add soluble starch during synthesis. The pseudo-second-order model and the Langmuir model were more in line with reaction. The maximum adsorption capacity for Cr(VI) by nZVI/SS/BC600 was 122.86 mg·g-1. The properties of the material were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, Brunauer-Emmett-Teller (BET), Fourier-transform infrared (FTIR), and X-ray diffraction (XRD). The results showed that the nZVI particles were uniformly supported on the biochar, and the BET surface areas of nZVI/SS/BC was 40.4837 m2·g-1, an increase of 8.79 times compared with the control group. Mechanism studies showed that soluble starch reduced the formation of metal oxides, thereby improving the reducibility of the material, and co-precipitates were formed during the reaction. All results indicated that nZVI/SS/BC was a potential repair material that can effectively overcome the limitations of nZVI and achieve efficient and rapid repair of Cr(VI).


Asunto(s)
Carbón Orgánico/química , Cromo/química , Contaminantes Químicos del Agua/química , Adsorción , Hierro/química , Pirólisis , Almidón , Temperatura , Contaminantes Químicos del Agua/análisis , Purificación del Agua , Difracción de Rayos X
10.
Ecotoxicol Environ Saf ; 208: 111624, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396144

RESUMEN

Phthalate esters (PAEs), such as dibutyl phthalate (DBP) and di-(2-ethylhexyl) phthalate (DEHP), are used extensively as additives and plasticizers, and have become ubiquitous in the environment. PAEs in the soil could have adverse effects on crop plants as well as humans via accumulations in food chain. Thus, it is important to explore strategies to reduce the bioavailability of phthalate esters. We investigated the effects of Fe-Mn oxide-modified biochar composite (FMBC) applications on the quality of wheat grown in DBP- and DEHP-polluted brown soil. The application of FMBC and biochar (BC) increased the wheat grain biomass by 9.71-223.01% and 5.40-120.15% in the DBP-polluted soil, and 10.52-186.21% and 4.50-99.53% in the DEHP-spiked soil in comparison to the controls. All FMBC treatments were better than the BC treatments, in terms of decreasing DBP and DEHP bioavailability for the wheat grains. The activities of the glutamine synthetase and glutamic-pyruvic transaminase in the flag leaves at the filling stage and of granule-bound starch synthase, soluble starch synthase, and adenosine diphosphate-glucose pyrophosphorylase in the grains at maturity increased significantly with increases in either the BC or FMBC applications. This, in turn, increased the starch, protein, and amino acid content in the wheat grains. Compared with the BC treatment, the FMBC amendment induced only slight increases in the aforementioned factors. This study offers novel insights into potential strategies for decreasing PAEs bioavailability in soil, with potential positive implications for crop quality and environmental health improvements.


Asunto(s)
Carbón Orgánico/química , Restauración y Remediación Ambiental/métodos , Ácidos Ftálicos/química , Contaminantes del Suelo/metabolismo , Triticum/fisiología , Dibutil Ftalato/análisis , Dibutil Ftalato/metabolismo , Dietilhexil Ftalato/metabolismo , Grano Comestible/química , Contaminación Ambiental , Ésteres/análisis , Humanos , Hierro/análisis , Óxidos/análisis , Plastificantes/análisis , Suelo/química , Contaminantes del Suelo/análisis , Triticum/metabolismo
11.
Ecotoxicol Environ Saf ; 208: 111626, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396146

RESUMEN

Soil application of biochars has been shown to effectively immobilize potentially toxic elements (PTEs). Soil water regime can also affect PTE availability. No previous studies have examined the interactive effect of biochars and soil water regime on Pb availability. Therefore, this study investigated the effect of high and low temperature (300 and 600°C) biochars derived from cow manure (CB), municipal compost (MB) and licorice root pulp (LB) applied at 3 wt%, under two soil moisture regimes (field capacity (FC) and saturation (ST)) on Pb release kinetics and chemical fractions in a Pb-contaminated calcareous soil. Results showed that CB and MB treatments significantly enhanced Pb stabilization compared to LB, attributed to their favorable chemical properties (high P, ash, carbonate, oxidizable C content and high pH) which could promote Pb conversion into stable chemical fractions. Immobilization of Pb was enhanced under saturated conditions compared to FC by the treatments, which is attributed to increased soil pH, reduction of metal oxides and possible formation of sulfides. The most significantly effective treatments were the CB300, CB600 and MB600 treatments under ST, as indicated by significant decrease in soil Pb mobility factor from 29.1% (CL+FC) to 21.2-22.9%, and 11.7-16.3% increase in non-EDTA-extractable Pb. Results of this study demonstrate that combined application of high ash biochars and soil water saturation significantly enhances Pb immobilization in calcareous soil.


Asunto(s)
Carbón Orgánico/química , Restauración y Remediación Ambiental/métodos , Plomo/química , Contaminantes del Suelo/química , Contaminación Ambiental , Estiércol , Óxidos , Suelo/química , Contaminantes del Suelo/análisis
12.
Molecules ; 26(2)2021 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-33419117

RESUMEN

In this study, a new method for economical utilization of coffee grounds was developed and tested. The resulting materials were characterized by proximate and elemental analyses, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and N2 adsorption-desorption at 77 K. The experimental data show bio-oil yields reaching 42.3%. The optimal activated carbon was obtained under vacuum pyrolysis self-activation at an operating temperature of 450 °C, an activation temperature of 600 °C, an activation time of 30 min, and an impregnation ratio with phosphoric acid of 150 wt.%. Under these conditions, the yield of activated carbon reached 27.4% with a BET surface area of 1420 m2·g-1, an average pore size of 2.1 nm, a total pore volume of 0.747 cm3·g-1, and a t-Plot micropore volume of 0.428 cm3·g-1. In addition, the surface of activated carbon looked relatively rough, containing mesopores and micropores with large amounts of corrosion pits.


Asunto(s)
Carbón Orgánico/química , Café/química , Aceites Vegetales/química , Polifenoles/química , Adsorción
13.
Molecules ; 26(3)2021 Jan 27.
Artículo en Inglés | MEDLINE | ID: mdl-33513953

RESUMEN

Soybean dreg is a by-product of soybean products production, with a large consumption in China. Low utilization value leads to random discarding, which is one of the important sources of urban pollution. In this work, porous biochar was synthesized using a one-pot method and potassium bicarbonate (KHCO3) with low-cost soybean dreg (SD) powder as the carbon precursor to investigating the adsorption of methylene blue (MB). The prepared samples were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analyzer (EA), Brunauer-Emmett-Teller (BET), X-ray diffractometer (XRD), Raman spectroscopy (Raman), Fourier transform infrared spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS). The obtained SDB-K-3 showed a high specific surface area of 1620 m2 g-1, a large pore volume of 0.7509 cm3 g-1, and an average pore diameter of 1.859 nm. The results indicated that the maximum adsorption capacity of SDB-K-3 to MB could reach 1273.51 mg g-1 at 318 K. The kinetic data were most consistent with the pseudo-second-order model and the adsorption behavior was more suitable for the Langmuir isotherm equation. This study demonstrated that the porous biochar adsorbent can be prepared from soybean dreg by high value utilization, and it could hold significant potential for dye wastewater treatment in the future.


Asunto(s)
Carbón Orgánico/química , Azul de Metileno/química , Soja/química , Adsorción , Bicarbonatos/química , Carbono/química , China , Cinética , Espectroscopía de Fotoelectrones/métodos , Porosidad , Compuestos de Potasio/química , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Termodinámica , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos
14.
Ecotoxicol Environ Saf ; 207: 111309, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32931970

RESUMEN

Cadmium (Cd2+), as the primary contaminant in Chinese soils, is dangerous to human health and ecological security. Invasive plant Spartina alterniflora in Chinese coastal wetlands presents a promising feedstock for biochar, which is an efficient adsorbent for heavy metal removal. S. alterniflora harvested in summer, autumn and winter were pyrolyzed to produce biochars. We analyzed the effects of harvest time and desalination of feedstock on biochar properties and Cd2+ adsorption capacity in aqueous solution. Biochars were characterized by pH probe, elemental analyzer, SEM, BJH, BET, and FTIR, and the Cd2+ concentrations were measured using AAS. Except pH (9.85-10.95) and nitrogen contents (0.71-1.59%), other biochar properties had no linear correlations with harvest time. Biochars produced from feedstock harvested in autumn had the highest carbon contents (73.25%) and lowest functional groups diversity (CC and -CHx). The pH and carbon contents (64.44-73.25%) were increased by desalination treatment. The surface area (0.48-2.27 m2/g), total pore volume (0.0015-0.0055 mL/g), mesopore volume (0.0015-0.0052 mL/g), and Cd2+ adsorption capacities (16.29-32.34 mg/g) were affected by desalination treatment, and the effects varied with harvest time. Biochars produced from desalted feedstock harvested in summer and untreated feedstock harvested in winter showed higher surface area, porosity, and Cd2+ adsorption capacity. Moderate salt contents (1.5-3.0% in chloride content) in feedstock promote the formation of biochars with higher surface area and porosity.


Asunto(s)
Cadmio/química , Carbón Orgánico/química , Poaceae/química , Contaminantes Químicos del Agua/química , Purificación del Agua , Adsorción , Cadmio/análisis , Carbono , Metales Pesados , Pirólisis , Suelo/química , Soluciones , Tiempo , Agua , Humedales
15.
Ecotoxicol Environ Saf ; 207: 111565, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-33254418

RESUMEN

Biochar plays an essential role in soil remediation, but its effect on the arsenic remediation has been controversial. In this study, hexadecyl trimethyl ammonium bromide (HDTMA-Br) modified or unmodified biochar on As mobility and bioavailability in soil were studied. The sequential extraction experiment showed that As in the original soil mainly existed in the occluded form (78.24%), followed by Fe‒As (20.72%) and Al‒As (0.88%) forms. With the addition of the modified and unmodified biochars, the contents of Ca‒As and Fe‒As increased by 0.36 - 0.95% and 2.06 - 3.36%, respectively, suggesting the increased potential toxicity of As. The NaH2PO4 extraction result showed that the unmodified biochar increased the As availability by 3.23 - 22.76%, whereas the HDTMA-modified biochar reduced the As availability by 4.80 - 13.41%. Pot experiment showed that the unmodified and modified biochar increased the biomass of Brassica pekinensis, and the modified biochar (HB5) decreased the uptake of As by plants by 80.77% compared to the unmodified biochar. In particular, the plant achieved better growth in the modified biochar treatment (average height 8.31 cm) than in the unmodified biochar treatment (average height 6.97 cm). Therefore, both biochars facilitated phase transformation of As from the stable to the mobile states in the soil. Nevertheless, the HDTMA-modified biochar had an effect on alleviating As bioavailability and toxicity.


Asunto(s)
Arsénico/análisis , Carbón Orgánico/química , Contaminantes del Suelo/análisis , Disponibilidad Biológica , Biomasa , Brassica , Inmovilización , Suelo
16.
Chemosphere ; 262: 128322, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32962838

RESUMEN

The presence of emerging contaminants such as pharmaceuticals in aquatic means presents as a serious threat, since their real consequences for the environment and human health are not well known. Therefore, this work consisted of preparing and characterize sludge-derived activated carbons (beverage sludge activated carbon - BSAC and acid-treated beverage sludge activated carbon - ABSAC) to investigate their use in the pharmaceuticals adsorption in aqueous media. The morphology study has demonstrated that ABSAC, unlike BSAC, exhibited an abundant porous structure, with smaller particles and bigger roughness. Adsorption results indicated that the ABSAC was more effective that BSAC, since it presented superior surface area (642 m2 g-1) and total pore volume (0.485 cm3 g-1) values. Pseudo-second-order kinetic model was more suitable to predict experimental data. Sips model best described the equilibrium data, with maximum adsorption capacities of 145, 105, and 57 mg g-1 for paracetamol, ibuprofen, and ketoprofen, respectively. Besides, the sludge-derived adsorbent was highly efficient in the treatment of a simulated drug effluent, removing 85.16% of the pharmaceutical compounds. Therefore, the material prepared in this work possesses intrinsic characteristics that make it a remarkable adsorbent to be applied in the treatment of pharmaceutical contaminants contained in industrial wastewater.


Asunto(s)
Acetaminofén/química , Antiinflamatorios no Esteroideos/química , Bebidas , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Adsorción , Carbón Orgánico/química , Humanos , Ibuprofeno/química , Cetoprofeno/química , Cinética , Aguas del Alcantarillado , Aguas Residuales , Agua , Contaminantes Químicos del Agua/análisis
17.
Chemosphere ; 262: 128031, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33182077

RESUMEN

In this research, raw jujube seeds (RJS) treated with sulphuric acid followed by ultrasonic treatment such as ultrasonic assisted jujube seeds (UAJS) based biochar have been experimented as a viable material for treating Zn(II) and Pb(II) contaminated water. The adsorption ability of UAJS was compared with RJS through Langmuir adsorption capacity. The produced adsorbents were analysed by using BET surface area and thermogravimetric analyses. The removal kinetics, isotherms and thermodynamic behaviours of metal ions adsorption by UAJS were studied. Adsorption equilibrium data were analysed using various equilibrium models and Freundlich isotherm was appropriate towards explain the adsorption characteristics. UAJS Langmuir capacity of 221.1 mg/g and 119.8 mg/g were obtained for Zn(II) ions and Pb(II) ions, respectively. The results observed that UAJS holds higher capacity as compared with RJS. The pseudo-first order model was relevant to address adsorption behaviour. The mechanism on the separation of metal ions by UAJS was tested using diffusion and Boyd models. The mechanism outcomes observed that the internal and external diffusion controlled the separation process. The thermodynamic results explain the separation process was viable, exothermic and natural. The electroplating industrial wastewater was also treated with UAJS biochar to remove the metal ions such as copper, nickel, chromium and zinc ions from wastewater. Desorption process showed that 0.1 N HCl provide the good results as compared with other desorbing agents. The adsorbent property is not lost till the maximum of 5 adsorption/desorption cycles. The produced UAJS can be a better adsorbent for treating the heavy metal polluted wastewater.


Asunto(s)
Carbón Orgánico/química , Galvanoplastia , Metales Pesados/análisis , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Adsorción , Difusión , Iones , Cinética , Semillas/química , Termodinámica , Ziziphus/química
18.
Chemosphere ; 262: 128072, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33182132

RESUMEN

A new synthesis method was developed to prepare an aluminum-based metal organic framework (MIL-96) with a larger particle size and different crystal habits. A low cost and water-soluble polymer, hydrolyzed polyacrylamide (HPAM), was added in varying quantities into the synthesis reaction to achieve >200% particle size enlargement with controlled crystal morphology. The modified adsorbent, MIL-96-RHPAM2, was systematically characterized by SEM, XRD, FTIR, BET and TGA-MS. Using activated carbon (AC) as a reference adsorbent, the effectiveness of MIL-96-RHPAM2 for perfluorooctanoic acid (PFOA) removal from water was examined. The study confirms stable morphology of hydrated MIL-96-RHPAM2 particles as well as a superior PFOA adsorption capacity (340 mg/g) despite its lower surface area, relative to standard MIL-96. MIL-96-RHPAM2 suffers from slow adsorption kinetics as the modification significantly blocks pore access. The strong adsorption of PFOA by MIL-96-RHPAM2 was associated with the formation of electrostatic bonds between the anionic carboxylate of PFOA and the amine functionality present in the HPAM backbone. Thus, the strongly held PFOA molecules in the pores of MIL-96-RHPAM2 were not easily desorbed even after eluted with a high ionic strength solvent (500 mM NaCl). Nevertheless, this simple HPAM addition strategy can still chart promising pathways to impart judicious control over adsorbent particle size and crystal shapes while the introduction of amine functionality onto the surface chemistry is simultaneously useful for enhanced PFOA removal from contaminated aqueous systems.


Asunto(s)
Aluminio/química , Caprilatos/análisis , Fluorocarburos/análisis , Dietilamida del Ácido Lisérgico/análogos & derivados , Estructuras Metalorgánicas/química , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Resinas Acrílicas/química , Adsorción , Carbón Orgánico/química , Dietilamida del Ácido Lisérgico/química , Tamaño de la Partícula , Solubilidad , Propiedades de Superficie
19.
Chemosphere ; 263: 127981, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32822946

RESUMEN

Hydrothermal carbonization technology has attracted wide attention in recent years owing to its advantages, e.g., high yield and clean production, compared with traditional pyrolysis. Anaerobic fermentation (AF) is a new method to modify carbon materials, which may improve the surface properties of hydrochar (HC). To explore whether AF has effects on different feedstocks based HCs, two kinds of HCs derived from wheat straw and poplar sawdust were treated with AF for different time in this study. By comparing the changes in physicochemical properties of anaerobic fermentative hydrochars (AFHCs), adsorption behaviors of Cadmium (Cd2+) on AFHCs were evaluated. The results showed that the surface electrical characteristics, specific surface area, and oxygen-containing functional groups of HCs improved significantly after AF treatment, which confirmed our hypothesis that AF is suitable for improving the adsorption of different feedstocks based HCs. The adsorption capacity of Cd2+ on AFHCs was significantly enhanced by a 3.1-3.4 times increase after AF treatment. The effect of AF treatment on wheat straw hydrochar (WHC) was more evident than poplar sawdust hydrochar (SHC). WHCs treated with AF own higher adsorption capacity of Cd2+, which was attributed to the higher negative charge, more exchangeable cations, and more oxygen-containing functional groups. The adsorption process was found to be a spontaneous endothermic reaction dominated by chemisorption and controlled by electrostatic attraction, ion exchange, functional groups complexation, and π-bonding coordination. These results were contributed to understanding the modification of HC by AF and its application in heavy metal pollution remediation.


Asunto(s)
Cadmio/metabolismo , Restauración y Remediación Ambiental/métodos , Adsorción , Anaerobiosis , Cadmio/análisis , Carbono , Carbón Orgánico/química , Fermentación , Metales Pesados , Triticum
20.
Chemosphere ; 262: 127820, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-32781332

RESUMEN

In this study, the behavior of mono-component (metronidazole/phosphate/nitrate, MET/PO43-/NO3-) and multi-component (MET+PO43-+NO3-) adsorption in fixed-bed adsorption column was investigated using Prosopis juliflora activated carbon (PJAC). The influence of column operating parameters such as bed depth (H: 5-15 cm), influent flow rate (Q: 0.5-2 L/h) and adsorbate concentration (Co: 25-100 mg/L) on breakthrough curves were evaluated. The experimental data was correlated with breakthrough models viz. Thomas, Adams-Bohart, Yoon-Nelson and bed depth service time (BDST) models. The results showed that the Thomas model fitted the experimental data better than other models in predicting the breakthrough characteristics for the removal of MET, PO43- and NO3- by PJAC. The maximum adsorption capacity found by Thomas model was 9.70, 8.21 and 5.57 mg/g for MET, PO43- and NO3-, respectively. In multi-component systems, antagonistic behavior in sorption of MET, PO43- and NO3- was observed and as a result, adsorption capacity was 1.2-1.5 folds lesser than that observed in mono-component system. In conclusion, results of the present study indicate that the PJAC can be successfully employed for the removal of MET, PO43- and NO3- using fixed-bed adsorption column; however, the column design for multi-component mixture should be based on rapid breakthrough sorbate.


Asunto(s)
Carbón Orgánico/química , Prosopis , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , Antibacterianos , Nutrientes , Contaminantes Químicos del Agua/análisis
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