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1.
Sci Total Environ ; 832: 155142, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35405241

RESUMO

CaCO3 filler masterbatch (CFM) is one of the most commonly used fillers in polypropylene (PP) and polyethylene (PE) products, and its is used to enhance the toughness of the polymer matrix. This is the first study to investigate the loss of CaCO3 and its impact on the adsorption ability of microplastics from plastic woven bags throughout the natural aging process. PP wire (PPw, 85% PP + 15% CFM) and PE film (PEf, 80% PE + 20% CFM) samples from plastic woven bags underwent a 250 d aging process in an open-air environment. Changes in the surface properties, morphology, CaCO3 content, and density of PPw microplastics (PPw-MP) and PEf microplastics (PEf-MP) after various durations of aging were investigated by scanning electron microscopy, infrared spectroscopy, and thermogravimetric analysis. The results showed that CaCO3 separated and agglomerated on the surfaces of PPw-MP and PEf-MP after 30 d. After 250 d, 42% of CaCO3 was lost from PPw-MP and 28% was lost from PEf-MP, decreasing the density of the microplastic samples. CFM presented a considerably higher adsorption affinity toward Cu(II) than PP particles and PE particles; therefore, its presence in plastic matrix increased the adsorption ability of the products. The adsorption of Cu(II) on PPw-MP and PEf-MP decreased with aging because of the loss of CaCO3 and poor development of O-containing functional groups. The qm value (maximum adsorption quantity of Langmuir model) decreased from 11.01 mg/g in unaged PPw-MP to 1.35 mg/g in aged PPw-MP, and from 9.00 mg/g in unaged PEf-MP to 1.05 mg/g in aged PEf-MP. Overall, the findings demonstrate that CaCO3 was crucial for the heavy metal-plastic interactions of the samples. Therefore, the results provide a basis to further clarify the potential environmental risks of plastic woven bags associated with heavy metal mobility.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Adsorção , Carbonato de Cálcio , Metais Pesados/análise , Microplásticos , Plásticos/química , Polipropilenos , Poluentes Químicos da Água/análise
2.
Anal Biochem ; 368(1): 100-10, 2007 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-17562322

RESUMO

In this study, micron-sized poly(styrene-co-glycidyl methacrylate) (PSt-GMA) fluorescent microspheres of 5.1microm in diameter were synthesized via dispersion polymerization of styrene and glycidyl methacrylate in the presence of 1,4-bis(5-phenyloxazol-2-yl) benzene (POPOP), which provided surface functional groups for covalent immobilization of enzymes. In an effort to study the biocompatibility of the microspheres' surface, glucose oxidase and beta-d-(+)-glucose were selected as a catalytic system for enzymatic assays. A colorimetric method was adopted in evaluating enzymatic activity by introducing horseradish peroxidase (HRP). Both the immobilization amount and the apparent activity of immobilized glucose oxidase from Aspergillus niger (GOD) were determined at different conditions. The results show that the immobilized enzymes retained approximately 28 to 34% activity, as compared with free enzymes, without pronounced alteration of the optimum pH and temperature. Kinetics studies show that the corresponding values of K(m) and V(max) are 23.2944 mM and 21.6450M/min.mg GOD for free enzymes and 35.1780 mM and 15.4799M/min.mg GOD for immobilized enzymes. The operational stability studies show that immobilized GOD could retain nearly 50% initial activity after being washed 20 times. The results suggest that the resultant PSt-GMA fluorescent microspheres provide a suitable surface for covalent immobilizing biomolecules; therefore, they have the potential of being used in fluorescence-based immunoassays in high-throughput screening or biosensors.


Assuntos
Enzimas Imobilizadas/química , Corantes Fluorescentes/química , Glucose Oxidase/química , Microesferas , Ácidos Polimetacrílicos/química , Aspergillus niger , Glucose Oxidase/metabolismo , Peroxidase do Rábano Silvestre/química , Peroxidase do Rábano Silvestre/metabolismo , Concentração de Íons de Hidrogênio , Oxazóis/química , Ácidos Polimetacrílicos/síntese química , Poliestirenos/síntese química , Poliestirenos/química , Temperatura
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