RESUMO
More recently, the application of semiconductor nanomaterials called quantum dots (QDs), has gained considerable attention as they possess tunable optoelectronic and physicochemical properties. There are several routes of QDs synthesis some of which include lithography, molecular beam epitaxy, and chemical reduction. However, most of these methods are expensive, labour intensive, and produce toxic by-products. Hence, the biosynthesis of QDs has been extensively researched for addressing the issues. This review elaborates on the biogenic synthesis of cadmium selenide, cadmium telluride, cadmium sulfide, lead sulfide, and zinc sulfide QDs using bacteria, and fungi. Further, we attempt to identify the underlying mechanism and critical parameters that can control the synthesis of QDs. Eventually, their application in detectors, photovoltaics, biodiesel, photocatalysis, infection-control, and bioimaging are discussed. Thus, biogenic QDs have a tremendous scope in future to emerge as next generation nanotheranostics although thorough pharmacokinetic, and pharmacodynamic studies are required.
Assuntos
Bactérias , Compostos de Cádmio , Fungos , Pontos Quânticos , Sulfetos , Compostos de Zinco , Pontos Quânticos/química , Bactérias/efeitos dos fármacos , Bactérias/metabolismo , Sulfetos/química , Sulfetos/metabolismo , Fungos/metabolismo , Fungos/efeitos dos fármacos , Compostos de Cádmio/química , Compostos de Zinco/química , Compostos de Selênio/química , Chumbo/química , TelúrioRESUMO
Rapid growth in the industry has released large quantities of contaminants, particularly metal discharges into the environment. Heavy metal poisoning in water bodies has become a major problem due to its toxicity to living organisms. In this study, we developed a 3-chloropropyl triethoxysilane incorporated mesoporous silica nanoparticle (SBA-15) based adsorbent utilizing the sol-gel process and Pluronic 123 (P123) as a structure-directing surfactant. Furthermore, the produced SBA-15 NPs were functionalized with bis(2-aminoethyl)amine (BDA) using the surface grafting approach. The physical and chemical properties of the prepared SBA-15@BDA NPs were determined using a variety of instruments, including small-angle X-ray diffraction (SAXS), Fourier-transform infrared (FTIR), scanning electron microscope (SEM), N2 adsorption-desorption, thermogravimetric, particle size distribution, and zeta potential analysis. The MSN has a large surface area of up to 574 m2/g, a pore volume of 0.57 cm3/g, and a well-ordered mesoporous nanostructure with an average pore size of 3.6 nm. The produced SBA-15@BDA NPs were used to adsorb selectively to lead (Pd2+) ions from an aqueous solution. The adsorption study was performed under various conditions, including the influence of solution pH, adsorbent dose, adsorption kinetics, adsorption selectivity in the presence of competing metal ions, and reusability. The results of the kinetic study demonstrated that SBA-15@BDA NPs absorb selectively Pb2+ ions via chemisorption. The SBA-15@BDA NPs show Pb2+ ions with a maximum adsorption capacity of ~ 88% and an adsorbed quantity of approximately ~ 112 mg/g from the studied aqueous solution. The adsorption mechanism relies on coordination bonding between Pb2+ ions and surface-functionalized amine groups on SBA-15@BDA NPs. Furthermore, the proposed SBA-15@BDA NPs adsorbent demonstrated excellent reusability over five cycles without significantly reducing adsorption performance. As a consequence, SBA-15@BDA NPs might serve as an effective adsorbent for the selective removal of Pb2+ ions from aqueous effluent.
Assuntos
Chumbo , Dióxido de Silício , Águas Residuárias , Poluentes Químicos da Água , Dióxido de Silício/química , Adsorção , Chumbo/química , Poluentes Químicos da Água/química , Águas Residuárias/química , Porosidade , Purificação da Água/métodos , Nanopartículas/química , Difração de Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Microscopia Eletrônica de VarreduraRESUMO
Heavy metal pollution in the environment has become a significant global concern due to its detrimental effects on human health and the environment. In this study, we report an electrochemical aptasensor for the simultaneous detection of Hg2+ and Pb2+. Gold nanoflower/polyethyleneimine-reduced graphene oxide (AuNFs/PEI-rGO) was introduced on the surface of a gold electrode to improve sensing performance. The aptasensor is based on the formation of a T-Hg2+-T mismatch structure and specific cleavage of the Pb2+-dependent DNAzyme, resulting in a dual signal generated by the Exo III specific digestion of methylene blue (MB) labeled at the 3' end of probe DNA-1 and the reduction of the substrate ascorbic acid (AA) catalyzed by the signal label. The decrease of MB signal and the increase of AA oxidation peak was used to indicate the content of Hg2+ and Pb2+, respectively, with detection limits of 0.11 pM (Hg2+) and 0.093 pM (Pb2+). The aptasensor was also used for detecting Hg2+ and Pb2+ in water samples with good recoveries. Overall, this electrochemical aptasensor shows promising potential for sensitive and selective detection of heavy metals in environmental samples.
Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Técnicas Eletroquímicas , Exodesoxirribonucleases , Chumbo , Mercúrio , Estruturas Metalorgânicas , Poluentes Químicos da Água , Mercúrio/análise , Chumbo/análise , Chumbo/química , Estruturas Metalorgânicas/química , Aptâmeros de Nucleotídeos/química , Exodesoxirribonucleases/química , Exodesoxirribonucleases/metabolismo , Poluentes Químicos da Água/análise , Técnicas Biossensoriais/métodos , Grafite/química , Ouro/química , Limite de Detecção , Eletrodos , DNA Catalítico/químicaRESUMO
The pollution of Pb2+ and Cd2+ in both irrigation water and soil, coupled with the scarcity of vital mineral nutrition, poses a significant hazard to the security and quality of agricultural products. An economical potassium feldspar-derived adsorbent (PFDA) was synthesized using potassium feldspar as the main raw material through ball milling-thermal activation technology to solve this problem. The synthesis process is cost-effective and the resulting adsorbent demonstrates high efficiency in removing Pb2+ and Cd2+ from water. The removal process is endothermic, spontaneous, and stochastic, and follows the quasi-second-order kinetics, intraparticle diffusion, and Langmuir model. The adsorption and elimination of Pb2+ and Cd2+ is largely dependent on monolayer chemical sorption. The maximum removal capacity of PFDA for Pb2+ and Cd2+ at room temperature is 417 and 56.3â¯mg·g-1, respectively, which is superior to most mineral-based adsorbents. The desorption of Pb2+/Cd2+ on PFDA is highly challenging at pH≥3, whereas PFDA and Pb2+/Cd2+ are recyclable at pH≤0.5. When Pb2+ and Cd2+ coexisted, Pb2+ was preferentially removed by PFDA. In the case of single adsorption, Pb2+ was mainly adsorbed onto PFDA as Pb2SiO4, PbSiO3·xH2O, Pb3SiO5, PbAl2O4, PbAl2SiO6, PbAl2Si2O8, Pb2SO5, and PbSO4, whereas Cd2+ was primarily adsorbed as CdSiO3, Cd2SiO4, and Cd3Al2Si3O12. After the complex adsorption, the main products were PbSiO3·xH2O, PbAl2Si2O8, Pb2SiO4, Pb4Al2Si2O11, Pb5SiO7, PbSO4, CdSiO3, and Cd3Al2Si3O12. The forms of mineral nutrients in single and complex adsorption were different. The main mechanisms by which PFDA removed Pb2+ and Cd2+ were chemical precipitation, complexation, electrostatic attraction, and ion exchange. In irrigation water, the elimination efficiencies of Pb2+ and Cd2+ by PFDA within 10â¯min were 96.0â¯% and 70.3â¯%, respectively, and the concentrations of K+, Si4+, Ca2+, and Mg2+ increased by 14.0â¯%, 12.4â¯%, 55.7â¯%, and 878â¯%, respectively, within 60â¯min. PFDA holds great potential to replace costly methods for treating heavy metal pollution and nutrient deficiency in irrigation water, offering a sustainable, cost-effective solution and paving a new way for the comprehensive utilization of potassium feldspar.
Assuntos
Irrigação Agrícola , Cádmio , Chumbo , Poluentes Químicos da Água , Qualidade da Água , Adsorção , Poluentes Químicos da Água/química , Chumbo/química , Cádmio/química , Irrigação Agrícola/métodos , Purificação da Água/métodos , Metais Pesados/química , Compostos de Potássio/química , Nutrientes , CinéticaRESUMO
This study investigated the feasibility of large-scale utilizing calcareous wastes (CW) of Angoran lead and zinc mine as aggregates in mortar production with the maximum possible substitution of natural aggregates. The main goal was to produce mortar (concrete with fine aggregates as fine as sand or smaller) from Angoran mine's calcareous wastes for maintenance in its underground spaces. Compared to concrete, such mortars with better fluidity can enter narrow spaces more easily. In addition, it can be used to build various structures around the mine. Therefore, multiple samples were prepared by replacing 0% (as the control sample), 20%, 40%, 60%, 80%, and 100% of natural aggregates with CW. Subsequently, compressive strength, flexural strength, water absorption, slump, and TCLP tests were conducted on these samples. The results revealed that the mortar sample with 80% CW exhibited significantly higher compressive strength at 3, 14, 28, and 56 days compared to both the control sample and other samples. Specifically, the compressive strength of this sample reached 35.5 MPa at 56 days, representing an 18.4% increase over the control sample. This indicates that the hydration of cement and the growth of C-S-H gel were enhanced. Analysis of the workability and slump of the samples indicated that as the percentage of natural aggregate replaced by CW increased, the fluidity of the mortar slightly decreased. In addition to mechanical properties like compressive strength, environmental aspects like heavy metal stabilization are also very important. So, TCLP tests conducted on the four heavy metals lead, zinc, copper, and cadmium demonstrated that the released amounts of these elements from all the samples were below the EPA standard limits. These findings confirm the effective stabilization of heavy metals in mortar samples. A comparison of SEM images revealed that the mortar sample made with 20% CW (with minimum compressive strength) exhibited a higher presence of ettringite compared to the sample made with 80% CW (with maximum compressive strength) after 28 days.
Assuntos
Materiais de Construção , Chumbo , Mineração , Zinco , Zinco/química , Chumbo/químicaRESUMO
Pb-contaminated soil poses significant environmental and health risks as well as soil stability issues. Research on sandy soils highlights CO2-enhanced reactive MgO as a promising solution for improving the solidification of Pb-contaminated soils. However, carbonation effects can differ markedly between soil types owing to varying soil properties. In this study, we evaluated the effects of CO2-enhanced reactive MgO on the engineering and environmental characteristics of Pb-contaminated red clay and explored its mechanism of carbonation solidification. The results showed that CO2-enhanced reactive MgO increased the strength of Pb-contaminated red clay to over 3 MPa within 1 h, which was approximately 25 times the strength of untreated soil (0.2 MPa) and significantly higher than that of reactive MgO-treated, uncarbonated soil (0.8 MPa). The pH of the carbonated soil (9-10) facilitated Pb2+ immobilization, and the increase over the initial parameter elevated the electrical conductivity value. Moreover, CO2-enhanced reactive MgO reduced the Pb2+ leaching concentration to below 0.1 mg/L, even at high Pb concentrations (10,000 mg/kg). Pb2+ transformed into lead carbonates during the carbonation process, with the hydrated magnesium carbonates forming a dense internal structure. This solidification mechanism included chemical precipitation, physical adsorption, and encapsulation. Notably, the carbonation time should be controlled within 1 h to prevent soil expansion. Together, these findings support the potential of CO2-enhanced reactive MgO for efficient and low-carbon application in the solidification of Pb-contaminated red clay.
Assuntos
Dióxido de Carbono , Argila , Chumbo , Poluentes do Solo , Solo , Dióxido de Carbono/química , Poluentes do Solo/química , Chumbo/química , Argila/química , Solo/química , Óxido de Magnésio/químicaRESUMO
The impact of functionality of biochar on pressing environmental issue of cadmium (Cd) and lead (Pb) co-contamination in simultaneous soil and water systems has not sufficiently reported. This study investigated the impact of Fe- and Mg-functionalized wheat straw biochar (Fe-WSBC and Mg-WSBC) on Cd and Pb adsorption/immobilization through batch sorption and column leaching trials. Importantly, Fe-WSBC was more effective in adsorbing Cd and Pb (82.84 and 111.24 mg g-1), regeneration ability (removal efficiency 94.32 and 92.365), and competitive ability under competing cations (83.15 and 84.36%) compared to other materials (WSBC and Mg-WSBC). The practical feasibility of Fe-WSBC for spiked river water verified the 92.57% removal of Cd and 85.73% for Pb in 50 mg L-1 and 100 mg L-1 contamination, respectively. Besides, the leaching of Cd and Pb with Fe-WSBC under flow-through conditions was lowered to (0.326 and 17.62 mg L-1), respectively as compared to control (CK) (0.836 and 40.40 mg L-1). In short, this study presents the applicable approach for simultaneous remediation of contaminated water and soil matrices, offering insights into environmentally friendly green remediation strategies for heavy metals co-contaminated matrices.
Assuntos
Cádmio , Carvão Vegetal , Recuperação e Remediação Ambiental , Chumbo , Poluentes do Solo , Solo , Triticum , Poluentes Químicos da Água , Carvão Vegetal/química , Cádmio/química , Triticum/química , Chumbo/química , Poluentes do Solo/química , Poluentes do Solo/análise , Adsorção , Poluentes Químicos da Água/química , Recuperação e Remediação Ambiental/métodos , Solo/químicaRESUMO
A label-free fluorescent sensing strategy for the rapid and highly sensitive detection of Pb2+ was developed by integrating Pb2+ DNAzyme-specific cleavage activity and a tetrahedral DNA nanostructure (TDN)-enhanced hyperbranched hybridization chain reaction (hHCR). This strategy provides accelerated reaction rates because of the highly effective collision probability and enriched local concentrations from the spatial confinement of the TDN, thus showing a higher detection sensitivity and a more rapid detection process. Moreover, a hairpin probe based on a G-triplex instead of a G-quadruplex or chemical modification makes hybridization chain reaction more controlled and flexible, greatly improving signal amplification capacities and eliminating labeled DNA probes. The enhanced reaction rates and improved signal amplification efficiency endowed the biosensors with high sensitivity and a rapid response. The label-free detection of Pb2+ based on G-triplex combined with thioflavin T can be achieved with a detection limit as low as 1.8 pM in 25 min. The proposed Pb2+-sensing platform was also demonstrated to be applicable for Pb2+ detection in tap water, river water, shrimp, rice, and soil samples, thus showing great potential for food safety and environmental monitoring.
Assuntos
Técnicas Biossensoriais , DNA Catalítico , Chumbo , Limite de Detecção , Hibridização de Ácido Nucleico , Chumbo/análise , Chumbo/química , DNA Catalítico/química , Técnicas Biossensoriais/métodos , Nanoestruturas/química , Poluentes Químicos da Água/análise , DNA/química , DNA/análise , Animais , Monitoramento Ambiental/métodos , Oryza/química , Poluentes Ambientais/análiseRESUMO
The aim of this research is to investigate novel compositions of oxyfluoride glasses doped with Neodymium (Nd3+) rare earth ions in the visible spectrum. This area has not been extensively studied in the existing literature, so it is vital to understand the favorable photoluminescence characteristics within this part of the electromagnetic spectrum. Therefore, we synthesized and characterized SiO2-PbO-PbF2 (SPF) doped with 1% neodymium (Nd3+) ions glasses. Spectroscopic analyses, based on Judd-Ofelt theory, were conducted on absorption spectra. These analyses enabled to determine absorption cross-sections, transition probabilities, and Judd-Ofelt intensity parameters Ω2, Ω4, and Ω6 for the different transition. Additionally, we calculated various radiative properties, such as branching ratios, integrated cross-sections, radiative lifetimes, emission cross-section, optical gain, and the multicolor behavior (chromaticity coordinates, CIE diagram) under different excitation wavelengths. The results suggest promising prospects for using these oxyfluoride silicate glasses doped with Nd3+ as a fluorophore, potentially for lasing materials around 630-nm emission and in other photonic applications.
Assuntos
Vidro , Neodímio , Silicatos , Dióxido de Silício , Neodímio/química , Vidro/química , Silicatos/química , Dióxido de Silício/química , Fluoretos/química , Chumbo/química , Óxidos/química , Fenômenos Ópticos , Luminescência , CorRESUMO
Rapidly and sensitively evaluating the acid value (AV) of edible oils is significant to ensuring food quality and safety. Cesium lead bromide perovskite nanocrystals (CsPbBr3 NCs) are an effective candidate for AV detection; however, their instability restricts wide applications. Herein, CsPbBr3@ZIF-8 was prepared by confining and growing CsPbBr3 NCs in situ into zeolitic imidazolate framework-8 (ZIF-8) to improve the stability, and a fluorescence sensor was established to evaluate the AV of edible oils. The results present that CsPbBr3 NCs (below 5 nm) with excellent optical properties were confined and grown in situ in micropores and mesopores of ZIF-8. Meanwhile, CsPbBr3@ZIF-8 had better long-term storage, ultraviolet-irradiation, and water-exposure stabilities, compared with CsPbBr3 NCs. Given the fact that free fatty acids (the major contributor of AV) decrease the fluorescence of CsPbBr3 NCs, the fluorescence intensities of CsPbBr3@ZIF-8 were negative-linearly related to oil AV (R2 = 0.9902) in 0.04-6.00 mg of KOH/g with a 0.06 mg of KOH/g limit of detection. Besides, the practical AV recovery was 92-101% with an average relative standard deviation of 2%. Furthermore, the detection time was 20 min. The response mechanism revealed that free fatty acids could remove surface ligands and increase surface defects to prompt the aggregation of CsPbBr3 NCs and the formation of lattice fringe dislocations, inducing a decrease in the fluorescence. Thus, a stable, sensitive, reliable sensor was established to evaluate the AV of edible oils.
Assuntos
Titânio , Zeolitas , Zeolitas/química , Titânio/química , Nanopartículas/química , Césio/química , Chumbo/análise , Chumbo/química , Óleos de Plantas/química , Corantes Fluorescentes/química , Espectrometria de Fluorescência , Óxidos/química , Brometos/química , Compostos de Cálcio/química , Estruturas Metalorgânicas/química , ImidazóisRESUMO
Face masks have emerged as a significant source of microplastics (MPs) under the influence of biotic and abiotic interactions. However, the combined effects of abiotic photoaging and biofilm-loading on mask-derived MPs as carriers of metal ions are not clear. We investigated the Pb(â ¡) adsorption onto polypropylene (PP) and polyurethane (PU) mask-derived MPs treated by photoaging, biofilm-loading, and both combinations, evaluating the composite risks. PU mask-derived MPs (1.157.47 mg/g) exhibited greater Pb(â ¡) adsorption capacity than PP mask-derived MPs (0.842.08 mg/g) because of the presence of intrinsic carbonyl functional groups. Photoaging (30.5%, 88.4%), biofilm-loading (110.7%, 87.1%), and both combinations (146.7%, 547.0%) of PP and PU masks enhanced Pb(â ¡) adsorption compared to virgin mask-derived MPs due to the increase of oxygen-containing functional groups. High-throughput sequencing indicated that the structural morphology and chemical composition of masks significantly affected the microbial community. Adsorption mechanisms involved electrostatic force and surface complexation. A combination of photoaging and biofilms increased the ecological risk index of mask-derived MPs in freshwater, showing the risk level to be high (PP mask) and very high (PU mask). This research highlights the crucial role of photoaging combined with biofilms in controlling metal ion adsorption onto mask-derived MPs, thereby increasing the composite risks.
Assuntos
Biofilmes , Chumbo , Microplásticos , Polipropilenos , Poliuretanos , Adsorção , Chumbo/química , Poliuretanos/química , Polipropilenos/química , Microplásticos/química , Microplásticos/toxicidade , Poluentes Químicos da Água/química , MáscarasRESUMO
Inspired by natural metallopeptides, our work focuses on engineering self-assembling nanostructures of C2-symmetric metallopeptide conjugates (MPC) from a pyridine-bis-tripeptide bioprobe that uniquely detects lead (Pb2+) ions by emitting a fluorescence signal at 450 nm, which is further intensified in the presence of DAPI (λem = 458 nm), enhancing the bioimaging quality. This study enables precise lead quantification by modulating the ionic conformation and morphology. Experimental and theoretical insights elucidate the nanostructure formation mechanism, laying the groundwork for materials encapsulation and advancing lead detoxification. Our proof-of-principle experiment, demonstrating actin filament recovery in lead-treated cells, signifies therapeutic potential for intracellular lead aggregation and introduces novel avenues in biotechnological applications within biomaterials science.
Assuntos
Chumbo , Humanos , Chumbo/química , Epitélio Pigmentado da Retina/metabolismo , Epitélio Pigmentado da Retina/citologia , Nanoestruturas/química , Linhagem Celular , Peptídeos/química , Peptídeos/metabolismo , Oligopeptídeos/química , Oligopeptídeos/metabolismo , Piridinas/químicaRESUMO
Dissolved organic matter (DOM) is a widely occurring substance in rivers that can strongly complex with heavy metal ions (HMIs), severely interfering with the electrochemical signal of anodic stripping voltammetry (ASV) and reducing the detection accuracy of HMIs in water. In this study, we investigated a novel advanced oxidation process (AOP) that involves the activation of peroxymonosulfate (PMS) using low-pressure ultraviolet (LPUV) radiation and CoFe2O4 photocatalysis. This novel AOP was used for the first time as an effective pretreatment method to break or weaken the complexation between HMIs and DOM, thereby restoring the electrochemical signals of HMIs. The key parameters, including the PMS concentration, CoFe2O4 concentration, and photolysis time, were optimized to be 6 mg/L, 12 mg/L, and 30 s for eliminating DOM interference during the electrochemical analysis of HMIs via LPUV/CoFe2O4-based photolysis. Investigations of the microstructure, surface morphology, specific surface area, and pore volume of CoFe2O4 were conducted to reveal the exceptional signal recovery capability of LPUV/CoFe2O4/PMS-based photolysis in mitigating interference from DOM during HMIs analysis. The PMS activation mechanism, which is critical to the signal recovery process, was elucidated by analyzing the reactive oxygen species (ROS) and the surface elemental composition of CoFe2O4. Additionally, the degradation and transformation behavior of humus-HMIs complexes were analyzed to study the mechanism of ASV signal recovery further. Notably, the detection results of HMIs in actual water samples obtained using the proposed pretreatment method were compared with those obtained from ICP-MS, yielding an RMSE less than 0.04 µg/L, which indicated the satisfactory performance of the proposed pretreatment method for the ASV detection of HMIs in complex actual samples.
Assuntos
Cádmio , Chumbo , Fotólise , Poluentes Químicos da Água , Poluentes Químicos da Água/química , Chumbo/química , Cádmio/química , Técnicas Eletroquímicas , Raios Ultravioleta , Oxirredução , Cobalto/química , Peróxidos/químicaRESUMO
Heavy metal ions and antibiotics were simultaneously detected in authentic water systems. This research, for the first time, employed synthesized sophorolipid-modified fly ash(SFA) to eliminate tetracycline(TC) and lead(Pb2+) from wastewater. Various characterization techniques, including SEM-EDS, FTIR, XPS, BET, and Zeta, were employed to investigate the properties of the SFA. The results showed that the sophorolipid modification significantly improved the fly ash's adsorption capacities for the target pollutants. The static adsorption experiments elucidated the adsorption behaviors of SFA towards TC and Pb2+ in single and binary systems, highlighting the effects of different Environmental factors on the adsorption behavior in both types of systems. In single systems, SFA exhibited a maximum adsorption capacity of 128.96 mg/g for Pb2+ and 55.57 mg/g for TC. The adsorption of Pb2+ and TC followed pseudo-second-order kinetics and Freundlich isotherm models. The adsorption reactions are endothermic and occur spontaneously. SFA demonstrates varying adsorption mechanisms for two different types of pollutants. In the case of Pb2+, the primary mechanisms include ion exchange, electrostatic interaction, cation-π interaction, and complexation, while TC primarily engages in hydrogen bonding, π-π interaction, and complexation. The interaction between Pb2+ and TC has been shown to improve adsorption efficiency at low concentrations. Additionally, adsorption-desorption experiments confirm the reliable cycling performance of modified fly ash, highlighting its potential as a cost-effective and efficient adsorbent for antibiotics and heavy metals.
Assuntos
Cinza de Carvão , Chumbo , Tetraciclina , Poluentes Químicos da Água , Cinza de Carvão/química , Adsorção , Chumbo/química , Chumbo/análise , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Tetraciclina/química , Tetraciclina/análise , Águas Residuárias/química , Antibacterianos/análise , Antibacterianos/química , Eliminação de Resíduos Líquidos/métodos , Cinética , Ácidos OleicosRESUMO
Pen shells (PS), a type of shellfish, are abundantly consumed, and their inedible shell residues are often discarded near the coast without consideration of reutilization. This study sought to investigate the use of natural pen shells (NPS) and calcined pen shells (CPS) to stabilize Pb and As-contaminated soil. During the investigation, NPS and CPS were applied to the contaminated soil in amounts ranging from 1 to 10 wt% and cured for 28 days. After the curing process, the mineral phase was examined through X-ray powder diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX) analysis. The XRD and SEM-EDX results revealed the presence of riversideite and ettringite, which contribute to Pb and As stabilization in the CPS-treated soil. The leachability of Pb and As in the treated soil was further examined with three types of chemical extraction methods. Extraction results using 0.1 M HCl displayed a notable pH fluctuation in the extractant due to the residual amendments (NPS and CPS). The fluctuation resulted in a strong correlation of leached Pb and As with the pH of the extractant, which might hinder an accurate assessment of stabilization. In order to minimize the effect of pH, an EDTA-NH4OAc extraction was employed, suggesting its potential as a suitable assessment method. EDTA-NH4OAc extraction showed a higher effectiveness of CPS than NPS at 10 wt% of input amounts. In the SBET extraction, that uses a strongly acidic solution, a higher As leachability was observed by increasing the addition of CPS, which implied a CPS-related chemical fixation mechanism. The comparison of various extraction methods showed a higher CPS effectiveness as compared to NPS. However, it was recommended that CPS-treated soil required caution in strongly acidic conditions, especially for arsenic. This study explores the applicability of PS, which has not been investigated as an amendment for Pb and As-contaminated soil previously. Furthermore, this study revealed that utilization of various extraction methods is beneficial for gaining a comprehensive understanding of the role of CaCO3-based amendment in Pb and As-contaminated soil.
Assuntos
Arsênio , Chumbo , Poluentes do Solo , Solo , Chumbo/química , Arsênio/química , Poluentes do Solo/química , Solo/química , AnimaisRESUMO
The issue of environmental contamination, particularly caused by the existence of heavy metal particles, is a major and widely recognized subject that receives substantial global attention. The remediation of Cu(II), Cd(II), Ni(II), and Pb(II) ionic metal particles from synthetic wastewater using chemically treated plant leaves of Ageratum conyzoides (TAC) as a biosorbent was investigated. The biosorption process was implemented utilizing a batch system, wherein several operational parameters were considered, including temperature, pH, agitation time, biosorbent dosage, and initial concentration of the metal ion. Langmuir, Freundlich, Temkin, and D-R isotherm models were used to evaluate equilibrium data. The analyzed parameter exhibits characteristics that were best fitted with the Langmuir isotherm. The observed biosorption capacities (qm) of Cu(II), Pb(II), Ni(II), and Cd(II) ions on the TAC were measured as 51.573, 30.49, 33.53, and 35.91 mg/g, respectively, at a temperature of 22 °C. The affinity sequence of these metal ions follows the order Cu(II) > Pb(II) > Ni(II) > Cd(II). The measured values for the biosorption free energy change (ΔG) of Cu(II), Pb(II), Cd(II), and Ni(II) metal ions ranged from -1.017 to -4.723, -1.368 to -3.612, -2.785 to -5.21, and -1.047 to -5.135 kJ/mol, respectively. The enthalpy (ΔH) for Cu(II), Pb(II), Cd(II), and Ni(II) were determined to be +19.33, +6.82, +14.83, and +38.07 kJ/mol, respectively. Similarly, the corresponding entropy changes (ΔS) for the same series of metal ions were recorded as +0.075, +0.064, +0.063, and +0.135 kJ/mol.K. The pseudo-second-order kinetic models yielded superior outcomes in comparison to the pseudo-first-order kinetic models. The findings of the experiment indicated that the TAC demonstrates favorable efficacy in extracting all four metal ions. Hence, the utilization of biomass derived from Ageratum conyzoides leaves has proven to be a viable and economically feasible approach for biosorption of all four metals.
Assuntos
Biomassa , Chumbo , Termodinâmica , Poluentes Químicos da Água , Cinética , Adsorção , Poluentes Químicos da Água/química , Chumbo/química , Chumbo/metabolismo , Concentração de Íons de Hidrogênio , Metais Pesados/química , Cobre/química , Cádmio/metabolismo , Cádmio/química , Temperatura , Níquel/química , Biodegradação Ambiental , Íons , Purificação da Água/métodosRESUMO
In recent years, researchers have increasingly focused on the development of multiphase trimetallic nanocomposites (TMNC) incorporating ternary metals or metal oxides, which hold significant potential as alternatives for combatting biofilms and bacterial infections. Enhanced oral health is ensured by the innovative techniques used to effectively prevent bacterial adherence and formation of biofilm on dental sutures. In this investigation, TMNC, which consists of Pb, Ag, and Cu, was synthesized using an autoclave-assisted sonochemical technique. Following synthesis, TMNC were characterized using FTIR, XRD, BET, XPS, TGA, and Raman spectroscopy to analyze their shape and microstructure. Subsequent evaluations, including MTT assay, antibacterial activity testing, and biofilm formation analysis, were conducted to assess the efficiency of the synthesized TMNC. Cytotoxicity and anti-human oral squamous cell carcinoma activities of TMNC were evaluated using the Human Oral Cancer cell line (KB) cell line through MTT assay, demonstrating a dose-dependent increase in anti-human oral squamous cell carcinoma activity against the KB cell line compared to the normal cell line, resulting in notably high cell viability. Furthermore, an ultrasonic probe was employed to incorporate TMNC onto dental suturing threads, with different concentrations of TMNC, ultrasonic power levels, and durations considered to determine optimal embedding conditions that result in the highest antibacterial activity. The inhibitory effects of TMNC, both in well diffusion assays and when incorporated into dental suturing threads, against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria on Mueller-Hinton agar (MHA) were assessed using various concentrations of TMNC. The results of the study indicated that the efficacy of TMNC in inhibiting bacterial growth on dental suturing threads remained impressive, even at low concentrations. Moreover, an evaluation of their potential to destabilize biofilms formed by S. aureus and E. coli, the two pathogens in humans, indicated that TMNC would be a promising anti-biofilm agent.
Assuntos
Antibacterianos , Biofilmes , Cobre , Chumbo , Nanocompostos , Prata , Humanos , Antibacterianos/farmacologia , Antibacterianos/química , Antibacterianos/síntese química , Nanocompostos/química , Cobre/química , Cobre/farmacologia , Prata/química , Prata/farmacologia , Biofilmes/efeitos dos fármacos , Linhagem Celular Tumoral , Chumbo/química , Ondas Ultrassônicas , Odontologia , Sobrevivência Celular/efeitos dos fármacos , Técnicas de Química Sintética , Staphylococcus aureus/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Escherichia coli/efeitos dos fármacosRESUMO
Lead (Pb) and arsenic (As) contaminated soils, caused by Pb and zinc (Zn) smelting activities, pose an urgent environmental issue. Magnetic biochar (MB) has been regarded as an increasingly appealing candidate for the remediation of multi-metals in contaminated soils or their leachate. Finding economically feasible preparation methods for MB and demonstrating its remediation potential is desperately required for the remediation of such complex smelting sites. In this study, a modified MB was prepared using an optimized co-precipitation method, and its application potential for Pb/As simultaneous removal based on the basic properties of a typical Pb/Zn smelting site was evaluated. The surface modifications of MB facilitated the encapsulation of various ultrafine iron oxide particles, predominantly γ-Fe2O3 and Fe3O4, whilst notably enhancing the presence of oxygen-containing surface functional groups. The adsorption of Pb(II) and As(III) by MB was well-described using the pseudo-second-order adsorption and Langmuir models. The existence of SO42- and Ca2+ in the soil leachate competed with the adsorption sites for Pb(II) and As(III). Notably, within the pH range of 5-9, the adsorption efficiency of Pb(II) by MB increased with the rising solution pH, whereas alterations in pH minimally affected the removal rate of As(III), maintaining a consistent removal rate exceeding 95%. Furthermore, dissolved organic matter (DOM) abundant in organic functional groups, particularly CO and CC groups, significantly augmented the adsorption affinity for both Pb(II) and As(III). An application rate of 2 g/L could effectively reduce the concentration of Pb(II) and As(III) in soil leachate to <0.05 mg/L. The findings demonstrated the potential of the prepared MB for simultaneous removal of As(III) and Pb(II) in soil leachate, which should be beneficial to multi-metals polluted soil remediation in Pb/Zn smelting sites.
Assuntos
Arsênio , Carvão Vegetal , Chumbo , Poluentes do Solo , Solo , Zinco , Chumbo/química , Carvão Vegetal/química , Zinco/química , Adsorção , Poluentes do Solo/química , Solo/química , Arsênio/química , Recuperação e Remediação Ambiental/métodosRESUMO
To study the pollutants immobilization and economy of biologically amended coastal soil, Alternanthera philoxeroides biomass (Bm), biochar (Bc), and dodecyldimethyl betaine (BS) modified Bc (BS-Bc) were used to amend coastal soil from Jialing, Fu, and Qu River. A runoff experiment was used to simulate the longitudinal migration and morphological changes of Pb(II) and chlortetracycline (CTC) in each amended coastal soil, and the economy of pollutants immobilization by different amended coastal soil were compared. The equilibrium time of Pb(II) and CTC in each amended coastal soil ranked in the order of BS-Bc-amended > Bc-amended > Bm-amended > unamended coastal soil. The average Pb(II) and CTC flow rate in different amended coastal soils presented an opposite trend with the equilibrium time. Pb(II) and CTC content all reduced with the increasing runoff length. Under the same soils, the content changes presented Bm and Bc amended > unamended > BS-Bc amended. CEC and clay content of coastal soils were the key factors affecting Pb(II) and CTC immobilization. The immobilization mechanisms were electrostatic attraction, ion exchange, surface precipitation, and complexation to Pb(II) and ion exchange and complexation to CTC. The economy of Pb(II) and CTC immobilization ranged from 0.5 to 9.0 and from 1.0 to 5.4 mg/¥, and coastal soil amended by BS-Bc had practical application value and high economy.
Assuntos
Clortetraciclina , Chumbo , Poluentes do Solo , Solo , Clortetraciclina/química , Chumbo/química , Poluentes do Solo/química , Poluentes do Solo/análise , Solo/química , Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodosRESUMO
Lake Nansi, primarily dominated by macrophytes, faces threats from heavy metals and antibiotics due to human activity. This study investigated sediment dissolved organic matter (SDOM) characteristics and complexation of lead (Pb) and tetracycline (TC) in barren zone (BZ) and submerged macrophytes zone (PZ). Additionally, a microbial degradation experiment was conducted to examine its impact on the regional variations in complexation. SDOM abundance and protein-like materials in PZ was significantly greater than in BZ, indicating a probable contribution from the metabolism and decomposition of submerged macrophytes. Both zones exhibited a higher affinity of SDOM for Pb compared to TC, with all four components participating in Pb complexation. Protein-like materials in PZ had a higher binding ability (LogKPb=4.19 ± 1.07, LogKTC=3.89 ± 0.67) than in BZ (LogKPb=3.98 ± 0.61, LogKTC=3.69 ± 0.13), suggesting a potential presence of organically bound Pb and TC due to the higher abundance of protein-like materials in PZ. Although microbial communities differed noticeably, the degradation patterns of SDOM were similar in both zones, affecting the binding ability of SDOM in each. Notably, the fulvic-like component C4 emerged as the dominant binding material for both Pb and TC in both zones. Degradation might increase the amount of organically bound TC due to the increase in the LogKTC.