Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.546
Filtrar
1.
J Environ Manage ; 299: 113626, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34488105

RESUMO

Polyvinyl chloride (PVC) and polycarbonate (PC) microplastics are major sources of hazardous chlorine and bisphenol A, threatening the ecosystem and environment. Plastic recycling can control the source of microplastics pollution, but the recycling of PVC and PC will be prevented by invalid separation. We established a novel and clean flotation method to separate PVC and PC microplastics by using aluminum coating. Trace amounts of Al(OH)3 can selectively coat the PVC microplastics surface due to its strong affinity for PVC. The contact angle of PVC decreases by 24° due to abundant hydroxyl groups of Al(OH)3 coating, whereas PC remained hydrophobic. Response surface methodology (RSM) combining Box-Behnken design (BBD) is used to optimize modification. A quadratic model is established to predict PC purity, explore the interaction between pH, aluminum chloride concentration, and ultrasonic duration. The recovery and purity of microplastics can exceed 99.65% with parameter optimization. The effects of multi-component, brand, shape, size, and mass ratio of plastics are utilized to evaluate the application potential. The suitable situations and limits of this method are disclosed. The aluminum coating offers significant benefits over other modifications in terms of reaction temperature, treatment time, and pollution prevention. Flotation based on aluminum coating provides a new insight for separating and recycling microplastics.


Assuntos
Cloreto de Polivinila , Eliminação de Resíduos , Alumínio , Ecossistema , Microplásticos , Plásticos , Cimento de Policarboxilato
2.
Mater Sci Eng C Mater Biol Appl ; 128: 112290, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34474841

RESUMO

Antimicrobial Polyvinyl chloride (PVC) was obtained by covalent bonding of zinc oxide nanoparticles, which have gained important achievements in antimicrobial fields because of their auspicious properties. This was achieved by grafting mercaptopropyltrimethoxysilane onto PVC, followed by the growth of zinc oxide nanoparticles covalently bonded on the polymer surface. In this study, the relationship between the physicochemical features of modified-surface PVC and antimicrobial activity on Staphylococcus aureus and Candida albicans was investigated. Zinc oxide with controllable morphologies (rods, rod flowers, and petal flowers) was synthesized on the polymer surface by tuning merely base-type and concentration using a hydrothermal process. The antimicrobial activity was more pronounced for rod flower morphology, because of their differences in microscopic parameters such as specific Zn-polar planes. This work provides an important hint for the safe use of PVC for biomedical devices by the structure surface tuning without injuring polymer bulk properties and a reduced risk of the covalently bonded nanoparticle dispersion in the host and the environment.


Assuntos
Anti-Infecciosos , Nanopartículas , Óxido de Zinco , Cloreto de Polivinila , Staphylococcus aureus , Óxido de Zinco/farmacologia
3.
Water Res ; 204: 117597, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34482095

RESUMO

In recent years, great efforts have been made to understand the capacity of microplastics to adsorb environmental pollutants; however, relatively little is known about the ability of microplastics to release inherent additives into peripheral environments. In this study, we investigated the leaching behavior of phthalate plasticizer from polyvinyl chloride (PVC) microplastics, in aqueous solutions relevant to aquatic and soil environments. It was found that plastic properties, such as particle size, plasticizer content and aging of plastics had a great effect on the leaching of dibutyl phthalate (DnBP). Phthalate release was generally higher in smaller particles and particles with higher phthalate content. Whereas, plastic aging caused by solar irradiation could either enhance phthalate release by increasing plastic hydrophilicity or decrease the leaching by reducing readily available fractions of phthalate. Regarding environmental factors, solution pH (3-9) and ionic strength (0-0.2 M NaCl) were found to have minor effect on phthalate release, while fulvic acid (0-200 mg/L) greatly promoted the release by improving phthalate solubility and solution-plastic affinity. Interestingly, we found that more DnBP was leached out when fulvic acid and NaCl coexisted, and the results from dissolved organic carbon (DOC) and three-dimensional fluorescence spectroscopy analyzes suggested that the leaching of other fulvic acid-like additives might have played a role. These findings would be helpful for predicting the potential of microplastics to release toxic additives under different environmental conditions.


Assuntos
Microplásticos , Poluentes Químicos da Água , Dibutilftalato , Plastificantes , Plásticos , Cloreto de Polivinila , Poluentes Químicos da Água/análise
4.
Molecules ; 26(16)2021 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-34443681

RESUMO

Accurate and precise application of ion-selective electrodes (ISEs) in the quantification of environmental pollutants is a strenuous task. In this work, the electrochemical response of alendronate sodium trihydrate (ALN) was evaluated by the fabrication of two sensitive and delicate membrane electrodes, viz. polyvinyl chloride (PVC) and glassy carbon (GC) electrodes. A linear response was obtained at concentrations from 1 × 10-5 to 1 × 10-2 M for both electrodes. A Nernstian slope of 29 mV/decade over a pH range of 8-11 for the PVC and GC membrane electrodes was obtained. All assay settings were carefully adjusted to obtain the best electrochemical response. The proposed technique was effectively applied for the quantification of ALN in pure form and wastewater samples, acquired from manufacturing industries. The proposed electrodes were effectively used for the determination of ALN in real wastewater samples without any prior treatment. The current findings guarantee the applicability of the fabricated ISEs for the environmental monitoring of ALN.


Assuntos
Indústria Farmacêutica , Resíduos de Drogas/análise , Técnicas Eletroquímicas , Resíduos Industriais/análise , Membranas Artificiais , Osteoporose/tratamento farmacológico , Águas Residuárias/química , Alendronato/análise , Alendronato/química , Carbono/química , Eletrodos , Vidro/química , Concentração de Íons de Hidrogênio , Cloreto de Polivinila/química , Potenciometria , Reprodutibilidade dos Testes
5.
J Electrocardiol ; 68: 124-129, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34419647

RESUMO

Multiple ECG algorithms exist to localize outflow tract PVCs. They can be invaluable in pre-procedure planning and patient counseling. We describe a case where the published algorithm for PVC localization did not predict the site of origin and successful ablation site. This case highlights the strengths and limitations of established ECG PVC localization algorithms.


Assuntos
Ablação por Cateter , Complexos Ventriculares Prematuros , Algoritmos , Eletrocardiografia , Humanos , Cloreto de Polivinila , Complexos Ventriculares Prematuros/diagnóstico , Complexos Ventriculares Prematuros/cirurgia
6.
Environ Sci Process Impacts ; 23(9): 1376-1384, 2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34368828

RESUMO

Polyvinyl chloride (PVC) is one of the most widely used thermoplastics but is also a material of concern because of the generation and release of harmful chemicals during its life cycle. Amongst the chemicals added to PVC are metal-based stabilisers and Sb-based halogenated flame retardant synergists. However, very little quantitative information exists on these additives, and in particular in PVC lost to the environment. In this study, the distribution of PVC amongst consumer plastics in societal circulation and plastics retrieved from marine and lacustrine beaches and agricultural soils are compared, along with the presence and concentrations of Ba, Cd, Pb, Sb, Sn and Zn as proxies for common metal-based additives and determined by X-ray fluorescence spectrometry. About 10% of consumer plastics and 2% of environmental plastics were constructed of PVC, with the discrepancy attributed to the long service lives and managed disposal of PVC used in the construction sector and the propensity of the plastic to sink in aquatic systems and evade detection. Metal-based additives, defined as having a metal concentration >1000 mg kg-1, were present in about 75% of consumer and environmental PVC, with Ba and Pb most abundant and Cd and Zn least abundant in both types of sample, and median concentrations statistically different only for Ba. Metals also appeared to be present as contaminants (defined as concentrations <1000 mg kg-1) arising from manufacturing or recycling. Metals in PVC are believed to pose little risk when the material is in use, but experimental evidence in the literature suggests that significant mobilisation and exposure may occur from PVC microplastics when ingested by wildlife.


Assuntos
Retardadores de Chama , Plásticos , Metais , Microplásticos , Cloreto de Polivinila
7.
J Mech Behav Biomed Mater ; 123: 104737, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34464902

RESUMO

This paper deals with the impact of the mechanical stresses on plasticized PVC infusion tubing. Stresses due to clamping were compared to those due to the use of a peristaltic pump. The degradation of the inner surface of plastic tubing due to a dynamic load with repeated flexion and compression was extensively studied in the case of peristaltic pump stress during extracorporeal (EC) acts. Even if clamping results in a less repeated stress, we show it can also lead to damages on the inner lumen of the tubing, especially in static conditions. As these degradations were responsible of particle shedding in the case of EC processes, a first evaluation of particular contamination was performed on the stressed infusion tubes.


Assuntos
Cloreto de Polivinila
8.
Molecules ; 26(16)2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34443422

RESUMO

A significant increase in the production of plastic materials and the expansion of their areas of application contributed to the accumulation of a large amount of waste of polymeric materials. Most of the polymer composition is made up of plasticizers. Phthalate plasticizers have been recognized as potentially hazardous to humans and the environment due to the long period of their biodegradation and the formation of persistent toxic metabolites. It is known that the industrial plasticizer dioctyl adipate is characterized by reduced toxicity and a short biodegradation period. The paper describes the synthesis of a number of new asymmetric esters based on adipic acid and ethoxylated butanol by azeotropic esterification. The receipt of the products was confirmed by IR spectra. The physicochemical properties of the synthesized compounds were investigated. The glass transition temperatures of PVC composites plasticized with alkyl butoxyethyl adipates were determined using DSC analysis. The ecological safety of esters was assessed by the phytotesting method. Samples of adipates were tested for fungal resistance, and the process of their biodegradation in soil was also studied. It is shown that the synthesized esters have good plasticizing properties and are environmentally safe. When utilized under natural conditions, they can serve as a potential source of carbon for soil microorganisms and do not form stable toxic metabolites; therefore, they are not able to accumulate in nature; when the plasticizers under study are disposed of in the soil, toxic substances do not enter.


Assuntos
Adipatos/toxicidade , Ecotoxicologia , Etanol/química , Plastificantes/toxicidade , Adipatos/síntese química , Adipatos/química , Biodegradação Ambiental , Varredura Diferencial de Calorimetria , Etanol/síntese química , Fungos/efeitos dos fármacos , Vidro/química , Lepidium/efeitos dos fármacos , Cloreto de Polivinila/química , Raphanus/efeitos dos fármacos , Solo , Espectrofotometria Infravermelho , Temperatura de Transição
9.
Sensors (Basel) ; 21(14)2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34300652

RESUMO

Intense interest in reference electrode design and fabrication has recently been enriched with the application of 3D printing of electrodes with salt-loaded PVC membranes. This type of material is attractive in sensor technology and is challenging to implement in 3D. In this report, several improvements and simplifications in the technology were focused on and supported by a fundamental electrochemical characterization.


Assuntos
Cloreto de Polivinila , Impressão Tridimensional , Eletrodos
10.
Int J Pharm Compd ; 25(4): 330-335, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34297695

RESUMO

Dexmedetomidine is a sedative medication with co-analgesic effects that has been used primarily in critical care and anesthesia as a continuous intravenous infusion. Its utility in the treatment of refractory agitated delirium is being investigated in other settings including palliative care, but continuous intravenous infusions are not always feasible during end-of-life care. Subcutaneous infusions are more commonly used in this setting, but smaller volumes and higher concentrations are typically required. Investigations into stability at these higher concentrations are required to address preparation and administration feasibility issues. The objective of this research was to study the chemical stability of high-concentration dexmedetomidine 20 mcg/mL prepared in polyvinyl chloride bags with 0.9% sodium chloride and storage up to 9 days under refrigeration and room temperature conditions. A total of four solutions of dexmedetomidine 20 mcg/mL in 0.9% sodium chloride were prepared in polyvinyl chloride bags under sterile conditions. Two bags were stored under refrigeration and two bags at room temperature. Duplicate samples were withdrawn from each bag at hours 0, 24, 48, 72, 96, 120, 144, 168, 192, and 216 and frozen at -20°C (total of 4 samples per time point at each storage condition). These samples were thawed and transferred to glass vials prior to their analysis by high-performance liquid chromatography electrospray ionization-tandem mass spectrometry and pH testing. All samples of dexmedetomidine 20 mcg/mL met stability criteria by retaining more than 90% of the initial concentration after 9 days under refrigeration and room temperature. There was no evidence of precipitation or color change during the study period. The pH reduced slightly over time under both refrigerated (5.7 to 4.5) and room temperature conditions (5.7 to 4.6). Dexmedetomidine solutions of 20 mcg/mL intended for subcutaneous use were stable in polyvinyl chloride bags containing 0.9% sodium chloride for 9 days under refrigeration and room temperature.


Assuntos
Dexmedetomidina , Cloreto de Polivinila , Cromatografia Líquida de Alta Pressão , Embalagem de Medicamentos , Estabilidade de Medicamentos , Armazenamento de Medicamentos , Infusões Intravenosas , Infusões Subcutâneas , Cloreto de Sódio
11.
Chemosphere ; 283: 131274, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34182647

RESUMO

Various chemical substances, such as potentially toxic trace metals, are used as plastic additives to improve the performance of polymers and extend the service life of plastic products. However, these added trace metals are likely released from plastic into the environment when the plastic becomes a pollutant, although the process is poorly understood. In this study, chemical ageing of commercial polyvinyl chloride (PVC) microplastics using hydrogen peroxide (H2O2) and natural ageing of PVC that had been added to an alkaline paddy soil were undertaken to evaluate the potential release of trace metals from PVC. Enhanced release of trace metals from PVC with the increasing H2O2 concentrations was observed, in which the released Pb was 1-2 orders of magnitude higher than other metals (p < 0.01). The released Cr, Ni, Pb, Cu, Zn, Cd and Mn accounted for 87.37%, 79.27%, 22.02%, 20.93%, 17.06%, 15.11%, and 11.02% of their total concentrations (0.28 ± 0.03, 0.08 ± 0.01, 13.67 ± 0.18, 1.07 ± 0.02, 2.20 ± 0.18, 0.05 ± 0.00 and 1.26 ± 0.08 mmol kg-1) in PVC after ageing with 30% H2O2, respectively. Compared with the control treatment without PVC addition, the concentrations of CaCl2-extractable Cu, Mn, Ni, Pb, and Zn in the soil treated with 5% PVC are significantly increased after incubation for 60 days (p < 0.01). In conclusion, chemical and natural ageing have the potential to lead to the release of Cu, Mn, Ni, Pb, and Zn from the commercial PVC into aquatic and terrestrial environments.


Assuntos
Metais Pesados , Poluentes do Solo , Monitoramento Ambiental , Peróxido de Hidrogênio , Metais Pesados/análise , Microplásticos , Plásticos , Cloreto de Polivinila , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
12.
Int J Mol Sci ; 22(10)2021 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-34065028

RESUMO

BACKGROUND: High-level occupational vinyl chloride (VC) exposures have been associated with hepatic hemangiosarcoma, which typically develops following a long latency period. Although VC is genotoxic, a more comprehensive mode of action has not been determined and diagnostic biomarkers have not been established. The purpose of this study is to address these knowledge gaps through plasma metabolomics. METHODS: Plasma samples from polyvinyl chloride polymerization workers who developed hemangiosarcoma (cases, n = 15) and VC exposure-matched controls (n = 17) underwent metabolomic analysis. Random forest and bioinformatic analyses were performed. RESULTS: Cases and controls had similar demographics and routine liver biochemistries. Mass spectroscopy identified 606 known metabolites. Random forest analysis had an 82% predictive accuracy for group classification. 60 metabolites were significantly increased and 44 were decreased vs. controls. Taurocholate, bradykinin and fibrin degradation product 2 were up-regulated by greater than 80-fold. The naturally occurring anti-angiogenic phenol, 4-hydroxybenzyl alcohol, was down-regulated 5-fold. Top affected ontologies involved: (i) metabolism of bile acids, taurine, cholesterol, fatty acids and amino acids; (ii) inflammation and oxidative stress; and (iii) nicotinic cholinergic signaling. CONCLUSIONS: The plasma metabolome was differentially regulated in polyvinyl chloride workers who developed hepatic hemangiosarcoma. Ontologies potentially involved in hemangiosarcoma pathogenesis and candidate biomarkers were identified.


Assuntos
Biomarcadores/sangue , Hemangiossarcoma/diagnóstico , Neoplasias Hepáticas/diagnóstico , Metaboloma , Doenças Profissionais/diagnóstico , Exposição Ocupacional/efeitos adversos , Cloreto de Polivinila/efeitos adversos , Estudos de Casos e Controles , Hemangiossarcoma/sangue , Hemangiossarcoma/induzido quimicamente , Hemangiossarcoma/epidemiologia , Humanos , Neoplasias Hepáticas/sangue , Neoplasias Hepáticas/induzido quimicamente , Neoplasias Hepáticas/epidemiologia , Masculino , Pessoa de Meia-Idade , Doenças Profissionais/sangue , Doenças Profissionais/induzido quimicamente , Doenças Profissionais/epidemiologia , Estados Unidos/epidemiologia
13.
Sci Total Environ ; 790: 148077, 2021 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-34090159

RESUMO

Pollutant-attached microplastics have received increasing attention in recent years. However, information regarding the influence of hydroxyl group content of pollutants on the adsorption and desorption behavior is unclear, which affects their fate and risks in the aquatic environment. In this study, we investigated the adsorption and desorption behavior of anthracene (ANT) and its hydroxy derivatives (OHAs), including 2-hydroxyanthracene (MOHA), 2,6-dihydroxyanthracene (DOHA), and 1,8,9-trihydroxyanthracene (TOHA) on polyvinyl chloride (PVC) microplastics, and their interaction mechanism through the batch, characterization, and computational experiments. The results showed that the adsorption of ANT and OHAs on PVC microplastics conformed to the pseudo-second-order kinetic model and was exothermic spontaneously. The adsorption efficiency on PVC followed the order of ANT > MOHA > DOHA > TOHA, indicating that increase in hydroxyl group substitution degree will inhibit pollutant adsorption on PVC microplastics. Conversely, the release amounts of MOHA from PVC into simulated gastric fluids were higher than those of ANT. Experimental and computational results suggested that the affinity of ANT/OHAs to PVC microplastics was the most likely outcome in hydrophobic effect, electrostatic repulsion, and CH-π interaction forces. These findings help elucidate the mechanisms of pollutant adsorption on microplastics and evaluate the risk of pollutant-attached microplastics in the aquatic environment.


Assuntos
Microplásticos , Poluentes Químicos da Água , Adsorção , Antracenos , Plásticos , Cloreto de Polivinila , Poluentes Químicos da Água/análise
14.
Mar Pollut Bull ; 169: 112566, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34089962

RESUMO

Polyvinyl chloride (PVC) is the third one after polyethylene and polypropylene in the production demand. It intends to grow further, causing an increase in the risk of health and ecological problems due to environmental accumulation and incineration. In the present study, we determined the biodegradative abilities of marine bacteria for PVC. Three potential marine bacterial isolates, T-1.3, BP-4.3 and S-237 (Vibrio, Altermonas and Cobetia, respectively) were identified after preliminary screening. They led to active biofilm formation, viability and protein formation on the PVC surface. The highest weight loss (1.76%) of PVC films was exhibited by BP-4.3 isolate after 60 days of incubation. Remineralization of PVC film was confirmed by CO2 assimilation assay. Change in surface topography was confirmed by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The functional group peak intensity was decreased for the terminal chlorine group at the region 1000-1300 cm-1, which indicated the dechlorination. Thermogravimetric, tensile strength and contact angle analysis showed a decline in the mechanical properties and a rise in PVC film's hydrophilic nature after biodegradation. These results demonstrated promising evidence of PVC degradation by marine bacteria.


Assuntos
Bactérias , Cloreto de Polivinila , Biodegradação Ambiental , Polietileno , Polipropilenos
15.
Bioresour Technol ; 337: 125442, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34175769

RESUMO

Polyvinyl chloride (PVC) was blended into bamboo powder during co-hydrothermal carbonization (Co-HTC) to understand the effects on the physicochemical properties and adsorbing ability of hydrochar. The properties of hydrochar were characterized by Zeta potential, elemental analyses, BET, FTIR, XPS, Boehm titration and SEM. The addition of PVC into bamboo in Co-HTC decreased the BET area, and pore volume and radius of hydrochar, but increased the contents of surface hydroxyl and carboxyl groups. The adsorption ability of hydrochar produced by addition of PVC at 473 K over methylene blue (MB) increased significantly. The main adsorption mechanism was electrostatic attraction by -N(CH3)2+ of MB and carboxylate of hydrochar, and hydrogen-bonding interaction through N atom of phenothiazine in MB and C-OH of hydrochar. Thus, Co-HTC offers a facile, green and economical alternative for conversion of waste into high-value adsorbents.


Assuntos
Azul de Metileno , Cloreto de Polivinila , Adsorção , Carbono , Temperatura
16.
ACS Appl Mater Interfaces ; 13(27): 32251-32262, 2021 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-34181389

RESUMO

Poly(vinyl chloride) (PVC) is the most used biomedical polymer worldwide. PVC is a stable and chemically inert polymer. However, microorganisms can colonize PVC producing biomedical device-associated infections. While surface modifications of PVC can help improve the antimicrobial and antiviral properties, the chemically inert nature of PVC makes those modifications challenging and potentially toxic. In this work, we modified the PVC surface using a derivative riboflavin molecule that was chemically tethered to a plasma-treated PVC surface. Upon a low dosage of blue light, the riboflavin tethered to the PVC surface became photochemically activated, allowing for Pseudomonas aeruginosa bacterial biofilm and lentiviral in situ eradication.


Assuntos
Biofilmes/efeitos dos fármacos , Luz , Viabilidade Microbiana/efeitos dos fármacos , Cloreto de Polivinila/química , Cloreto de Polivinila/farmacologia , Riboflavina/química , Inativação de Vírus/efeitos dos fármacos , Fenômenos Fisiológicos Bacterianos/efeitos dos fármacos , Fenômenos Fisiológicos Bacterianos/efeitos da radiação , Biofilmes/efeitos da radiação , Viabilidade Microbiana/efeitos da radiação , Inativação de Vírus/efeitos da radiação
17.
Sensors (Basel) ; 21(9)2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-34062895

RESUMO

Levofloxacin (LF) is a medically important antibiotic drug that is used to treat a variety of bacterial infections. In this study, three highly sensitive and selective carbon paste electrodes (CPEs) were fabricated for potentiometric determination of the LF drug: (i) CPEs filled with carbon paste (referred to as CPE); (ii) CPE coated (drop-casted) with ion-selective PVC membrane (referred to as C-CPE); (iii) CPE filled with carbon paste modified with a plasticizer (PVC/cyclohexanone) (referenced as P-CPE). The CPE was formulated from graphite (Gr, 44.0%) and reduced graphene oxide (rGO, 3.0%) as the carbon source, tricresyl phosphate (TCP, 47.0%) as the plasticizer; sodium tetrakis[3,5-bis(trifluoromethyl)phenyl] borate (St-TFPMB, 1.0%) as the ion exchanger; and levofloxacinium-tetraphenylborate (LF-TPB, 5.0%) as the lipophilic ion pair. It showed a sub-Nernstian slope of 49.3 mV decade-1 within the LF concentration range 1.0 × 10-2 M to 1.0 × 10-5 M, with a detection limit of 1.0 × 10-5 M. The PVC coated electrode (C-CPE) showed improved sensitivity (in terms of slope, equal to 50.2 mV decade-1) compared to CPEs. After the incorporation of PVC paste on the modified CPE (P-CPE), the sensitivity increased at 53.5 mV decade-1, indicating such improvement. The selectivity coefficient (log KLF2+,Fe+3pot.) against different interfering species (Na+, K+, NH4+, Ca2+, Al3+, Fe3+, Glycine, Glucose, Maltose, Lactose) were significantly improved by one to three orders of magnitudes in the case of C-CPE and P-CPE, compared to CPEs. The modification with the PVC membrane coating significantly improved the response time and solubility of the LF-TPB within the electrode matrix and increased the lifetime. The constructed sensors were successfully applied for LF determination in pharmaceutical preparation (Levoxin® 500 mg), spiked urine, and serum samples with high accuracy and precision.


Assuntos
Preparações Farmacêuticas , Cloreto de Polivinila , Carbono , Composição de Medicamentos , Eletrodos , Concentração de Íons de Hidrogênio , Levofloxacino , Potenciometria
18.
Sensors (Basel) ; 21(10)2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-34069524

RESUMO

Surfactant liquid-membrane type sensors are usually made of a PVC, ionophore and a plasticizer. Plasticizers soften the PVC. Due to their lipophilicity, they influence the ion exchange across the membrane, ionophore solubility, membrane resistance and, consequently, the analytical signal. We used the DMI-TPB as an ionophore, six different plasticizers [2-nitrophenyl-octyl-ether (P1), bis(2-ethylhexyl) phthalate (P2), bis(2-ethylhexyl) sebacate (P3), 2-nitrophenyl phenyl ether (P4), dibutyl phthalate (P5) and dibutyl sebacate (P6)] and a PVC to produce ionic surfactant sensors. Sensor formulation with P1 showed the best potentiometric response to four usually used cationic surfactant, with the lowest LOD, 7 × 10-7 M; and potentiometric titration curves with well-defined and sharp inflexion points. The sensor with P6 showed the lowest analytical performances. Surfactant sensor with P1 was selected for quantification of cationic surfactant in model solutions and commercial samples of disinfectants and antiseptics. It showed high accuracy and precision in all determinations, with recovery from 98.2 to 99.6, and good agreement with the results obtained with surfactant sensor used as a referent one, and a standard two-phase titration method. RDS values were lower than 0.5% for all determinations.


Assuntos
Anti-Infecciosos Locais , Desinfetantes , Concentração de Íons de Hidrogênio , Plastificantes , Cloreto de Polivinila , Potenciometria , Tensoativos
19.
Bull Environ Contam Toxicol ; 107(4): 748-753, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33963438

RESUMO

Microplastics (MPs) are ubiquitously in ecosystem and have evoked wide attention. The potential risk of MPs to the ecosystems is associated with MPs and the additives such as Pb, which serves as a traditional stabilizer. However, the release of Pb from MPs remains largely unknown. In this study, we evaluated the release of Pb from recycled polyvinyl chloride (PVC) under UV-irradiation. The release process was dominated by two processes: H+ facilitated dissolution of Pb, and light-induced hydroxyl radical (·OH) caused C-H bond cleavage from PVC with the generation of alkyl radical. The effects of pH and coexisting low molecular weight organic acids (LMWOAs) were also evaluated. Lower pH speeds up the Pb release from MPs. The LMWOAs act as a filter of UV to restrain the Pb release. Overall, this study shows the release of Pb from recycled PVC MPs and indicates the potential risk of Pb to the environment.


Assuntos
Microplásticos , Poluentes Químicos da Água , Ecossistema , Chumbo , Plásticos , Cloreto de Polivinila
20.
Environ Sci Pollut Res Int ; 28(37): 51072-51087, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33977428

RESUMO

This work is focused on the design and preparation of polymer inclusion membranes (PIMs) for potential applications for stannous cation sequestration from water. For this purpose, the membranes have been synthesized employing two polymeric matrices, namely, polyvinylchloride (PVC) and cellulose triacetate (CTA), properly enriched with different plasticizers. The novelty here proposed relies on the modification of the cited PIMs by selected extractants expected to interact with the target cation in the membrane bulk or onto its surface, as well as in the evaluation of their performances in the sequestration of tin(II) in solution through chemometric tools. The composition of both the membrane and the solution for each trial was selected by means of a D-Optimal Experimental Design. The samples such prepared were characterized by means of TG-DTA, DSC, and static contact angles investigations; their mechanical properties were studied in terms of tensile strength and elastic modulus, whereas their morphology was checked by SEM. The sequestering ability of the PIMs toward stannous cation was studied by means of kinetic and isotherm experiments using DP-ASV. The presence of tin in the membranes after the sequestration tests was ascertained by µ-ED-XRF mapping on selected samples.


Assuntos
Membranas Artificiais , Polímeros , Cátions , Cloreto de Polivinila , Água
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...