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1.
Braz. j. biol ; 83: e242536, 2023. tab, graf
Artigo em Inglês | MEDLINE, LILACS, VETINDEX | ID: biblio-1339356

RESUMO

Abstract Chromium (VI) a highly toxic metal, a major constituent of industrial waste. It is continuously release in soil and water, causes environmental and health related issues, which is increasing public concern in developing countries like Pakistan. The basic aim of this study was isolation and screening of chromium resistant bacteria from industrial waste collected from Korangi and Lyari, Karachi (24˚52ʹ46.0ʺN 66˚59ʹ25.7ʺE and 24˚48ʹ37.5ʺN 67˚06ʹ52.6ʺE). Among total of 53 isolated strains, seven bacterial strains were selected through selective enrichment and identified on the basis of morphological and biochemical characteristics. These strains were designated as S11, S13, S17, S18, S30, S35 and S48, resistance was determined against varying concentrations of chromium (100-1500 mg/l). Two bacterial strains S35 and S48 showed maximum resistance to chromium (1600 mg/l). Bacterial strains S35 and S48 were identified through 16S rRNA sequence and showed 99% similarity to Bacillus paranthracis and Bacillus paramycoides. Furthermore, growth condition including temperature and pH were optimized for both bacterial strains, showed maximum growth at temperature 30ºC and at optimum pH 7.5 and 6.5 respectively. It is concluded that indigenous bacterial strains isolated from metal contaminated industrial effluent use their innate ability to transform toxic heavy metals to less or nontoxic form and can offer an effective tool for monitoring heavy metal contamination in the environment.


Resumo O cromo (VI), metal altamente tóxico, é um dos principais constituintes dos resíduos industriais. É liberado no solo e na água, causa problemas ambientais e de saúde de crescente preocupação pública em países em desenvolvimento como o Paquistão. O objetivo básico deste estudo foi o isolamento e a triagem de bactérias resistentes ao cromo de resíduos industriais coletados em Korangi e Lyari, Karachi (24˚52'46,0"N 66˚59'25,7"E e 24˚48'37,5"N 67˚06'52,6"E). Do total de 53 cepas isoladas, sete cepas bacterianas foram selecionadas por enriquecimento seletivo e identificadas com base em características morfológicas e bioquímicas. Essas cepas foram designadas como S11, S13, S17, S18, S30, S35 e S48, apresentaram alta resistência aos metais contra concentrações variáveis (100-1500 mg / l) de cromo. Já as cepas S35 e S48 foram identificadas por meio da sequência 16S rRNA e apresentaram 99% de similaridade com Bacillus paranthracis e Bacillus paramycoides. Além disso, as condições de crescimento incluindo temperatura e pH foram otimizadas e ambas as cepas bacterianas apresentaram crescimento máximo na temperatura de 30 ºC, enquanto seu pH ótimo foi observado em 7,5 e 6,5, respectivamente. Conclui-se que o potencial de resistência dessas bactérias resistentes ao cromo pode ser efetivamente utilizado na remoção de cromo de efluentes industriais contaminados. Técnicas de base biológica usando bactérias ajudarão a fornecer métodos mais baratos e ecológicos de remoção, recuperação e desintoxicação de cromo.


Assuntos
Cromo , Metais Pesados , Bacillus , Bactérias/genética , Biodegradação Ambiental , RNA Ribossômico 16S/genética , Resíduos Industriais/análise
2.
Sci Rep ; 12(1): 9618, 2022 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35688864

RESUMO

Chromium (III) salts are highly applied for tanning purpose in tannery industries. The purpose of this study was removal and recovery of chromium(III) from tannery wastewater with a strong cation exchange resin. For this purpose, Amberlite 252 ZU was chosen as a strong cation exchange resin. In the first part of this study, The MINEQL+ computer program was applied depending on the optimum concentration and pH for determining Cr species in aqueous solutions. The second part of the work consists of measuring the exchange equilibrium of H+ ions and Cr(III) ions. Therefore, solutions containing fixed amounts of chromium were brought into contact with different amounts of resins. The evaluation of the obtained equilibrium parameters was done by surface complexing theory. Retention and regeneration steps were successfully performed in the column without any significant change up to 10 cycles. Efficiency was between 90 and 98% in removal studies, and between 81 and 92% in recovery studies. The results showed that a strong cation exchange resin Amberlite 252 ZU can be successfully used for chromium removal and recovery.


Assuntos
Cromo , Poluentes Químicos da Água , Resinas de Troca de Cátion , Concentração de Íons de Hidrogênio , Águas Residuárias
3.
J Mater Sci Mater Med ; 33(6): 54, 2022 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-35691951

RESUMO

Particles released from cobalt-chromium-molybdenum (CoCrMo) alloys are considered common elicitors of chronic inflammatory adverse effects. There is a lack of data demonstrating particle numbers, size distribution and elemental composition of bone marrow resident particles which would allow for implementation of clinically relevant test strategies in bone marrow models at different degrees of exposure. The aim of this study was to investigate metal particle exposure in human periprosthetic bone marrow of three types of arthroplasty implants. Periprosthetic bone marrow sections from eight patients exposed to CoCrMo particles were analyzed via spatially resolved and synchrotron-based nanoscopic X-ray fluorescence imaging. These analyses revealed lognormal particle size distribution patterns predominantly towards the nanoscale. Analyses of particle numbers and normalization to bone marrow volume and bone marrow cell number indicated particle concentrations of up to 1 × 1011 particles/ml bone marrow or 2 × 104 particles/bone marrow cell, respectively. Analyses of elemental ratios of CoCrMo particles showed that particularly the particles' Co content depends on particle size. The obtained data point towards Co release from arthroprosthetic particles in the course of dealloying and degradation processes of larger particles within periprosthetic bone marrow. This is the first study providing data based on metal particle analyses to be used for future in vitro and in vivo studies of possible toxic effects in human bone marrow following exposure to arthroprosthetic CoCrMo particles of different concentration, size, and elemental composition. Graphical abstract.


Assuntos
Cobalto , Molibdênio , Ligas , Medula Óssea , Cromo , Humanos , Metais , Síncrotrons , Vitálio
4.
Ecotoxicol Environ Saf ; 240: 113676, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35653974

RESUMO

Chromium (Cr) is mainly found in the form of organic-Cr(III) complexes in the natural environment and industrial waste. The widespread existence of composite contaminants composed of organic matter (OM) and Cr pose a serious ecological threat, and its potential interaction and removal need to be further summarised. Organic ligands, such as carbohydrates, nitrogen compounds, phenolic compounds, humus substances (HS), and low molecular weight organic acids (LMWOAs), play an important role in governing the speciation, mobility, and absorption and desorption of Cr in the environment. Moreover, growing evidence indicates that oxygen-containing functional groups (e.g., carboxyl, hydroxyl, and phosphate) are closely related to the complexation of Cr(III). Advanced oxidation processes (AOPs) are efficient and widely applicable technologies. However, the re-complexation of oxidation intermediates with Cr(III) and the formation and accumulation of much more toxic Cr(VI) species hinder the possible utilisation of AOPs. In this paper, the sources and harmful effects of organic-Cr(III) complexes are reported in detail. The complexation behaviour and structure of the organic-Cr(III) complexes are also described. Subsequently, the application of AOPs in the decomplexation and degradation of organic-Cr(III) complexes is summarised. This review can be helpful for developing technologies that are more efficient for organic-Cr(III) complex removal and establishing the scientific background for reducing Cr discharge Cr into the environment.


Assuntos
Cromo , Resíduos Industriais , Cromo/química , Radical Hidroxila , Compostos Orgânicos , Oxirredução
5.
Chem Commun (Camb) ; 58(50): 7094-7097, 2022 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-35661839

RESUMO

Described here is the chromium-catalyzed cleavage of C(aryl)-SMe bonds leading to coupling with organomagnesium to give functionalized benzaldehydes under mild conditions. This reaction was promoted specifically by a low-cost and simple CrCl2 salt used as a precatalyst, enabling synchronous activations of ortho-C(aryl)-SMe and ortho'-C(aryl)-H bonds to achieve difunctionalization of benzaldimines. This work provided a strategy for accessing arylated, alkylated, and diarylated benzaldehyde derivatives as a result of the couplings of C(aryl)-SMe and C(aryl)-SMe/C(aryl)-H bonds promoted with cost-effective Cr catalysis.


Assuntos
Benzaldeídos , Cromo , Catálise
6.
Mar Pollut Bull ; 180: 113826, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35696894

RESUMO

In this study, 214 surface sediment samples were collected from the offshore area of the Dongying coast and were analysed for heavy metals; particularly, their concentrations and pollution status were evaluated. The copper (Cu) and chromium (Cr) distributions were similar, their concentrations were the highest in the northeast areas and the Xiaoqing River estuary, where dominated by fine-grained sediments. Higher concentrations of lead (Pb), zinc (Zn), cadmium (Cd), and arsenic (As) were generally found in the offshore area of the study location, and the highest Cd concentration was observed in the Xiaoqing River estuary. The sediments were not polluted by Cu, Pb, Zn, and Cr; they were not polluted or moderately polluted by Cd and As. Results of the principal component analysis indicated that Cu, Pb, Zn, and Cr were derived from natural sources and Cd and As were derived from anthropogenic sources.


Assuntos
Arsênio , Metais Pesados , Poluentes Químicos da Água , Arsênio/análise , Cádmio/análise , China , Cromo/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Chumbo/análise , Metais Pesados/análise , Medição de Risco , Rios , Poluentes Químicos da Água/análise , Zinco/análise
7.
J Environ Sci (China) ; 122: 50-61, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35717090

RESUMO

The widespread contamination of water systems with antibiotics and heavy metals has gained much attention. Intimately coupled visible -light-responsive photocatalysis and biodegradation (ICPB) provides a novel approach for removing such mixed pollutants. In ICPB, the photocatalysis products are biodegraded by a protected biofilm, leading to the mineralization of refractory organics. In the present study, the ICPB approach exhibited excellent photocatalytic activity and biodegradation, providing up to ∼1.27 times the degradation rate of sulfamethoxazole (SMX) and 1.16 times the Cr(VI) reduction rate of visible-light-induced photocatalysis . Three-dimensional fluorescence analysis demonstrated the synergistic ICPB effects of photocatalysis and biodegradation for removing SMX and reducing Cr(VI). In addition, the toxicity of the SMX intermediates and Cr(VI) in the ICPB process significantly decreased. The use of MoS2/CoS2 photocatalyst accelerated the separation of electrons and holes, with•O2- and h+ attacking SMX and e- reducing Cr(VI), providing an effective means for enhancing the removal and mineralization of these mixed pollutants via the ICPB technique. The microbial community results demonstrate that bacteria that are conducive to pollutant removal are were enriched by the acclimation and ICPB operation processes, thus significantly improving the performance of the ICPB system.


Assuntos
Poluentes Ambientais , Sulfametoxazol , Biofilmes , Catálise , Cromo , Titânio
8.
Sci Rep ; 12(1): 9821, 2022 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-35701474

RESUMO

The co-pyrolysis of oily sludge with biomass to prepare carbon materials is not only an effective way to mitigate oily sludge pollution, but it is also a method of obtaining carbon materials. In this study, a carbon material (OS-CS AC) was obtained by the direct co-pyrolysis of oily sludge (OS) and corn stalks (CS) and then applied to Cr(VI) removal. According to the hydroxy and carboxy masking experiments and the characterization of OS-CS AC by FT-IR, SEM, XPS, XRD, and N2 physical adsorption-desorption, Cr(VI) can be adsorbed efficiently through pore filling, the surface oxygen-containing functional groups can promote the reduction of Cr(VI) to Cr(III) through electron donors, and the greater the electrostatic attraction between the electron-donating functional groups of OS-CS AC and the Cr(VI) is, the stronger the ability to remove Cr(VI). In addition, the removal process was discussed, and the results indicated that the McKay kinetic model, Langmuir isotherm model and Van't Hoff thermodynamic model were the most suitable models for removal. The main factors affecting the removal of Cr(VI) were discussed, and the removal of Cr(VI) reached 99.14%, which gives a comprehensive utilization way of oily sludge and corn stalks.


Assuntos
Esgotos , Poluentes Químicos da Água , Adsorção , Carbono , Carvão Vegetal , Cromo/análise , Cinética , Óleos , Pirólise , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/análise , Zea mays
9.
Sci Rep ; 12(1): 9817, 2022 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-35701510

RESUMO

The aim of the study was to determine how feeding rats a high-fat diet (F) supplemented with various forms of chromium affects the responses of the immune and redox systems, as well as epigenetic changes in the ileal tissue and the course of fermentation processes in the caecum. The rats received a pharmacologically relevant dose 0.3 mg Cr/kg body weight in form of chromium(III) picolinate (Cr-Pic), chromium (III)-methionine (Cr-Met), or chromium nanoparticles (Cr-NPs). The F increased DNA oxidation and raised the level of interleukin IL-6. The F was shown to reduce the intensity of fermentation processes in the caecum while increasing the activity of potentially harmful enzymes in the faeces. The addition of Cr in the form of Cr-NPs and Cr-Met in rats fed F beneficially increased mobilization of enzymes of the DNA repair pathway. All forms of Cr, but especially Cr-NPs, beneficially decreased the activity of caecal bacterial ß-glucuronidase, faecal ß-glucosidase and ß-glucuronidase. However, due to the increase in level of cytokine IL-2 in small intestinal wall, induced by all tested forms of chromium, it is difficult to state conclusively that this element can mitigate unfavourable pro-inflammatory and oxidative changes induced by a F in the small intestinal wall.


Assuntos
Cromo , Dieta Hiperlipídica , Animais , Dieta Hiperlipídica/efeitos adversos , Suplementos Nutricionais , Epigênese Genética , Fermentação , Glucuronidase , Intestinos , Oxirredução , Estresse Oxidativo , Ratos
10.
Sci Total Environ ; 838(Pt 1): 155713, 2022 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-35660107

RESUMO

Chronic exposure to hexavalent chromium compounds [Cr(VI)] is associated with an increased risk of cancers, but the molecular mechanisms remain to be elucidated. In this study, we found that CXCL5 levels in peripheral blood monocytes (PBMCs) and plasma from workers with occupational exposure to Cr(VI) were dramatically upregulated compared to non-exposure healthy subjects, and plasma C-X-C Motif Chemokine Ligand 5 (CXCL5) CXCL5 levels were positively correlated with Cr concentrations in subjects' toenails. Zinc chromate exposed mice showed higher levels of CXCL5 and its receptor CXCR2 in lung tissues, and in PBMCs. Similar CXCL5 upregulation was evident in Cr(VI)-induced transformed (Cr-T) cells with long-term Cr(VI) treatment. Mechanistic studies showed that elevated CXCL5 expression levels were regulated by Cr(VI)-induced histone modifications and DNA hypomethylation, and that the c-Myc/p300 complex was a key upstream regulator of histone H3 acetylation. CXCL5 overexpression promoted Cr(VI)-induced the epithelial to mesenchyme transition (EMT) by upregulating zinc finger E-box binding homeobox 1 (ZEB1) to promote tumor development. Our findings identify a novel mechanism by which CXCL5 is upregulated and promotes EMT and carcinogenesis upon chronic Cr(VI) exposure. Our work also implies that CXCL5 mRNA and protein levels will elevate in PBMCs and serum after occupational Cr(VI) exposure, which may be a potential target and biomarker for cancer prevention and health surveillance among populations exposed to Cr(VI).


Assuntos
Carcinogênese , Cromo , Animais , Carcinogênese/induzido quimicamente , Quimiocina CXCL5 , Cromo/toxicidade , Epigênese Genética , Humanos , Camundongos , Regulação para Cima
11.
Water Sci Technol ; 85(11): 3259-3270, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35704409

RESUMO

Nanoscale zero-valent iron-supported biochar pellets (nZVI)-(BP) were synthesized via liquid-phase reduction and applied to estrogen removal, including estrone (E1), 17ß-estradiol (E2), and estriol (E3). The performance of nZVI-BP, with respect to its characterization, removal kinetics, and isotherms, was investigated. The results showed that the adsorption equilibrium was reached within 10 min of exposure. The adsorption capacity of estrogen decreased with increasing solute pH and nZVI-BP dosage. The adsorptivity increased with increasing initial estrogen concentration. The estrogen behavior followed a pseudo-second-order kinetic model. The adsorption data of different initial estrogen concentrations fitted to Freundlich adsorption isotherms. In addition, a preliminary discussion of the adsorption mechanism of nZVI-BP for estrogens was provided.


Assuntos
Poluentes Ambientais , Poluentes Químicos da Água , Adsorção , Carvão Vegetal , Cromo/química , Estrogênios , Ferro/química , Poluentes Químicos da Água/química
12.
J Colloid Interface Sci ; 624: 219-232, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35660890

RESUMO

Polymeric N-rich carbon nitride of C3N5 is being utilized as a new visible-light-driven catalyst due to its narrower bandgap (∼2.0 eV). Building step-scheme (S-scheme) heterojunction by coupling with other semiconductors especially those own oxygen vacancies (OVs) can further upgrade the photocatalytic performance of C3N5-based photocatalysts. Herein, a novel S-scheme heterojunction of OVs mediated Bi2MoO6/C3N5 was fabricated by in-situ growing Bi2MoO6 nanoparticles with OVs on C3N5 nanosheets. Benefiting from the efficient separation and transfer of high energetic charge carriers by S-scheme charge migration, enriched structural defects, as well as the close contact by the in-situ growth, the heterojunction exhibited superior visible-light photocatalytic performance toward the removal of tetracycline (TC) and Cr(VI) than C3N5, Bi2MoO6, and their mechanical mixture under visible light. The TC degradation routes and the bio-toxicity evolution of TC were explored. Moreover, the photocatalytic mechanism for TC decomposition and Cr(VI) reduction over Bi2MoO6/C3N5 with OVs were elucidated. This work presents a newfangled vision for designing promising C3N5-based S-scheme heterojunction photocatalysts for pollution control.


Assuntos
Bismuto , Oxigênio , Antibacterianos/química , Bismuto/química , Cromo , Molibdênio , Nitrilas , Oxigênio/química , Tetraciclina
13.
Spectrochim Acta A Mol Biomol Spectrosc ; 278: 121343, 2022 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-35567825

RESUMO

In this paper, a facile and rapid fluorescence "on-off-on" strategy for the detection of chromium (Cr(VI)) and ascorbic acid (AA) was developed, which was based on the water-soluble carbon dots (CDs). The CDs was synthesized by a microwave-assisted treatment of L-tartaric acid, citric acid, and urea. The CDs have many advantages, such as high fluorescence quantum yield (20.5%) and good fluorescence stability. Based on inner filter effect (IFE) and static quenching, the fluorescence of the CDs can be quenched by Cr(VI) quickly; while the reduction of IFE and reducing action can make the fluorescence of the CDs recover by AA efficiently. Moreover, under the optimal experimental conditions, the CDs had a good detection performance for Cr(VI) in the range of 0.8 âˆ¼ 189 µM with the limit of detection (LOD) of 0.16 µM. The linear detection for AA was ranged from 0.43 to 25.7 µM with a LOD of 0.1 µM. More importantly, the as-constructed fluorescence detecting platform was successfully applied for Cr(VI) and AA detection in the environmental samples and fruit samples, respectively. In addition, the application potential of the CDs in fluorescent films and anti-counterfeiting materials was further discussed in detail. This work will provide a novel idea for designing a portable sensor based on the CDs to quickly and sensitively detect Cr(VI) and AA.


Assuntos
Cromo , Pontos Quânticos , Ácido Ascórbico , Carbono , Limite de Detecção , Espectrometria de Fluorescência
14.
Chemosphere ; 302: 134802, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35504466

RESUMO

In account of environmental remediation, an ideal photocatalyst was fabricated for the effective treatment of water systems. Herein, dual heterojunctions framed CuWO4/Bi2WO6/MnS nanocomposite (NCs) was synthesized via simple co-precipitation method followed by ultra-sonicated assisted route. The prepared NCs were investigated its photocatalytic degradation performance using para-chlorophenol (4-CP) and reduction of chromium VI (Cr (VI)) under visible light irradiation. The photocatalyst were characterized by various analytical techniques including XRD, HR-TEM, XPS, UV-vis DRS, FE-SEM, EIS, PL, ESR, Raman and N2 adsorption and desorption studies. The excellent photodegradation of 4-CP was observed within 180 min by the NCs. Similarly, the Cr (VI) reduction was about 97% within 140 min. The effect of pH and influence of different dosage of NCs and 4-CP on the photodegradation efficiency was investigated. The reusability and stability of the NCs was examined over 6 consecutive runs where the XRD and XPS confirm the structural stability of the prepared NCs. The scavenging experiment were carried out to elucidate the mechanism and the active species involved were O2-• and OH• radicals. The TOC analysis affirmed the complete mineralization of the prepared NCs. The ecotoxicity analysis was carried out to determine the toxicity effect of intermediates using ECOSAR software and the end product toxicity was also evaluated against E. coli and S. epidermis. The end product toxicity study also confirmed that the degraded product was less toxic compared to parent compound. Further, the genotoxicity study was done to understand the environmental impact using allium cepa and results confirms that there are no causes of cytotoxicity & genotoxicity by the prepared NCs. Therefore, the prepared NCs can be economical, efficient with excellent photocatalytic performance and environment friendly.


Assuntos
Clorofenóis , Recuperação e Remediação Ambiental , Nanocompostos , Poluentes Químicos da Água , Catálise , Clorofenóis/toxicidade , Cromo , Escherichia coli , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade
15.
Chemosphere ; 302: 134862, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35533931

RESUMO

The narrow light-response range and high electron/hole recombination rate greatly restrict the widespread use of photocatalytic technology. The integration of exposing dominant facet of semiconductor and Z-scheme heterostructures designing is expected to break those barriers. Herein,In this work, hydrothermal and ultrasonic stirring methods were used to selectively exposed the (001) and (110) facet of BiOI to construct the BiOI/CdS heterostructures. The obtained BiOI(001)/CdS material shown the maximum degradation for tetracycline-based antibiotics (Oxytetracycline, Tetracycline and Doxycycline), and excellent reduction of hexavalent chromium. Combining the electron spin resonance and scavenger experiments, the superior photocatalytic capacity was attributed to the generation of superoxide and hydroxyl radicals. DFT calculation results shown BiOI(001)/CdS performed high binding energy and adsorption energy for hexavalent chromium, and the different work function between BiOI(001) and CdS confirmed the building of internal electric field, thereby increased the charge separation. Finally, the Gaussian 09 and HPLC-MS program investigated the attack sites of free radicals and degradation pathways in the degradation of antibiotics. This study not only provides a potential photocatalyst, also gives an in-depth understanding of the photocatalytic properties of heterojunctions constructed by different exposed crystal facets.


Assuntos
Bismuto , Cromo , Antibacterianos , Bismuto/química , Catálise , Cromo/química , Tetraciclina/química
16.
Chemosphere ; 302: 134865, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35533936

RESUMO

As the important carriers of environmental pollutants, microplastics have a significant impact on the migration, transformation and toxicology of heavy metals. In this paper, the adsorption behavior of Cr(VI) on PE/PS/PA microplastics under UV irradiation was studied. The research results show that the adsorption capacity of original PA is the strongest, followed by PS and PE. The specific surface area of the aged microplastics increased and new functional groups were formed, so the adsorption of three microplastics for Cr(VI) was stronger than that before aging. The average saturation adsorption of Cr(VI) by PA/PS/PE increased respectively from 730.69 µg/g, 146.11 µg/g and 75.61 µg/g to 736.31 µg/g, 318.75 µg/g and 136.78 µg/g. The Langmuir and Freundlich models showed that the adsorption is more consistent with the Freundlich model, indicating that adsorption is mainly based on multi-molecular layer adsorption on non-homogeneous surfaces. In the Cu-Cr polluted water, Cu has different effects on the adsorption behavior. Cu can promote the adsorption of Cr(VI) by PE and PS, while inhibited the adsorption by PA. In addition, environmental conditions such as temperature, pH and dissolved organic matter also have significant effects on adsorption behavior. Mechanistic analysis confirmed that electrostatic interaction plays an important role. Secondly, based on the surface physicochemical properties of the microplastics, surface complexation and van der Waals forces also significantly enhance the adsorption of Cr(VI) on the aged microplastics.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Adsorção , Cromo , Metais Pesados/química , Microplásticos , Plásticos/química , Poluentes Químicos da Água/análise
17.
Chemosphere ; 302: 134859, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35533942

RESUMO

Due to its low vapor pressure, chromium (Cr) mostly emitted as fly ash particles (especially PM2.5) into environment in coal-fired power plants (CFPPs). The ultra-low emission (ULE) control technologies used in current CFPPs may be beneficial to reducing both the regular pollutants and hazardous trace elements (e.g., Cr), but the insight into the removal efficiency of Cr by different upgrading air pollution cleaning devices (APCDs) and the environmental stability of the Cr-bearing wastes produced from those APCDs in the ULE CFPPs has rarely reported. This study investigated and compared the distribution and emission characteristics of Cr in a Chinese CFPP before and after ULE, and the leaching behavior of Cr after ULE retrofitting in combustion byproducts was also revealed. The results showed that Cr was primarily captured in bottom and fly ashes (80.85%), followed by gypsum (0.02%) and sludge from wet electrostatic precipitator (WESP) (4.52 × 10-4%), with only 3.02 × 10-8% emitted into the atmosphere. Additional WESP had a large removal efficiency of Cr with the value of 92.04%, and the overall Cr removal efficiency of selective catalytic reduction (SCR) equipment, electrostatic precipitator (ESP), wet flue gas desulphurization (WFGD) system, and WESP equipped after ULE retrofitting was 99.99%. Notably, although the mass percentage of Cr in WESP sludge was negligible, the concentration of Cr in WESP sludge was 324.04 mg/kg. The leaching concentrations of Cr in combustion byproducts were in the descending order: fly ash > WESP sludge > bottom ash > gypsum. The atmospheric emission factor of Cr in the studied power plant was 1.08 mg/t coal, which was significantly lower than those of the CFPPs before ULE retrofitting. Therefore, the ULE retrofitting for CFPP was beneficial to reduce Cr emissions. More attention should be paid to the subsequent processing problem of solid combustion byproducts, especially the WESP sludge.


Assuntos
Poluentes Atmosféricos , Cinza de Carvão , Poluentes Atmosféricos/análise , Sulfato de Cálcio , China , Cromo , Carvão Mineral/análise , Cinza de Carvão/análise , Monitoramento Ambiental , Centrais Elétricas , Esgotos
18.
Sci Total Environ ; 837: 155791, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35561923

RESUMO

FeS nanoparticles loaded on nitrogen-doped biochar (FeS/BNC) were fabricated by pyrolyzing coffee husks pretreated with Mohr's salt. The nitrogen doping and FeS loading of biochar are simultaneously achieved in one-pot pyrolysis. The elemental analysis, SEM, TEM, XRD, XPS, Raman, FTIR and N2 adsorption-desorption technologies were used to characterize the composition and structure of FeS/NBC. The appraisement for removing aqueous Cr(VI) testified that FeS/NBC offered a synergistic scavenging effect of Cr(VI) by FeS and NBC. The effect of crucial experimental conditions (FeS/NBC dosage, foreign ions, initial pH and concentration of Cr(VI) solution) were investigated. The Cr(VI) removal capacity was as high as 211.3 ± 26 mg g-1 under the optimized condition. The practicability of FeS/NBC was examined by using simulated actual samples from tap water and lake water. The mechanism examination showed that surface adsorption/reduction and solution reduction were implicated in the removal of Cr(VI). The current work introduces a novel FeS/NBC composite prepared by an in situ pyrolysis method with excellent potential for chromium pollution remediation.


Assuntos
Poluentes Químicos da Água , Adsorção , Carvão Vegetal/química , Cromo/análise , Compostos Ferrosos , Nitrogênio/análise , Água , Poluentes Químicos da Água/análise
19.
Ecotoxicol Environ Saf ; 240: 113692, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35636236

RESUMO

The form of chromium (Cr) is an important factor that influences its bioavailability and potential toxicity, while the difference of Cr bioaccumulation between organic and inorganic Cr has been rarely investigated. The present study compared the bioaccumulation of organic Cr (e.g., chromium picolinate (CrPic)) and inorganic Cr (e.g., trivalent (Cr(III)) and hexavalent (Cr(VI))) in juvenile coral trout (Plectropomus leopardus). The fish were exposed to a gradient level of different forms of dietary Cr for 66 days. Then the Cr bioaccumulation in fish were comparatively quantified between CrPic, Cr(VI) and Cr(III) groups. The results showed that the Cr bioaccumulation was form- and tissue-specific, dose- and time-dependent. Specifically, the newly bioaccumulated Cr in fish generally increased with the increasing dietary Cr level and exposure time, while the CrPic groups accumulated the highest Cr in most cases, followed by Cr(VI) and Cr(III) groups. The highest Cr content was observed in gut for CrPic groups, while it was highest in heart for Cr(VI) and Cr(III) groups, followed by kidney, skin, fin, liver, gill, bone, eyes and muscle in order. Overall, the results here firstly demonstrated that the dietary organic Cr(III) had significantly higher bioaccumulation than inorganic Cr (Cr(III) and Cr(VI)). Our findings suggested the complexity and variability of form-specific Cr bioavailability and toxicity should be cautiously evaluated in aquatic environments, which has been largely overlooked previously.


Assuntos
Antozoários , Truta , Animais , Bioacumulação , Cromo/toxicidade , Ácidos Picolínicos
20.
Sci Total Environ ; 836: 155549, 2022 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-35490816

RESUMO

Sewage sludge, including those after biological or thermochemical treatments, has the potential to be used as fertilizers for recycle of resources. However, its potential ecological risk is also of great concern to policy making. This study employed comprehensive ecological risk assessment (ERA) methods to evaluate the risk caused by the toxic metal(loid)s in sewage sludge throughout China. The conventional geo-accumulation index and potential ecological risk index revealed that cadmium (Cd) and mercury (Hg) were of significant concern in treating sewage sludge before land application, but chromium (Cr) and zinc (Zn) were preferred by potential affected proportion (PAF) and overall risk probability (ORP) of species sensitivity distribution (SSD). Because SSD considered both the community and the ecotoxicity of toxic metal(loid)s, it was more advantageous and promising in assessing ecological risks caused by land application of sewage sludge. Based on the predicted no-effect concentration (PNEC) of toxic metal(loid) calculated by hazardous concentration that cause death of 50% of species (HC50) by SSD, the maximum allowable disposal amount (MADA) of sewage sludge in the whole China indicated that chromium (Cr) should be totally eliminated because of its high risks in the present background soil. After excluding Cr, the MADA of sewage sludge in China was 3.24 × 106 t and 6.47 × 107 t under land application scenarios with high and low ecological risks, respectively. Additionally, the MADA could be increased by mixing sewage sludge with deeper soil in wider areas. This study emphasized that local laws and regulations on land application of sewage sludge and the subsequent ERA system need to be addressed in the future.


Assuntos
Mercúrio , Metais Pesados , Poluentes do Solo , China , Cromo/toxicidade , Monitoramento Ambiental/métodos , Metais Pesados/análise , Metais Pesados/toxicidade , Medição de Risco , Esgotos/análise , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
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