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1.
Food Chem ; 355: 129547, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-33773454

RESUMO

The detection of food adulterants and toxicants can prevent a large variety of adverse health conditions for the global population. Through the process of rapid sensing enabled by deploying novel and robust sensors, the food industry can assist in the detection of adulterants and toxicants at trace levels. Sensor platforms which exploit graphene-based nanomaterials satisfy this requirement due to outstanding electrical, optical and thermal properties. The materials' facile conjugation with linkers and biomolecules along with the option for further enhancement using nanoparticles results in highly sensitive and selective sensing characteristics. This review highlights novel applications of graphene derivatives for detection covering three important approaches; optical, electrical (field-effect) and electrochemical sensing. Suitable graphene-based sensors for portable devices as point-of-need platforms are also presented. The future scope of these sensors is discussed to showcase how these emerging techniques will disrupt the food detection sector for years to come.


Assuntos
Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Grafite/química , Eletricidade , Nanotecnologia
2.
Ecotoxicol Environ Saf ; 208: 111422, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33091776

RESUMO

Potable water in developing countries often contains levels of toxic metals that exceed the recommended international limits, with impacts on human health. The aim of the present study was to develop a low cost aerogel synthesised from graphene oxide (GO) cross-linked with alginate to remove Pb2+ from potable water. Aerogels were made by a sol-gel of the composite materials followed by a freeze drying method. The shape of the aerogels were 50 mm diameter disks, 5 mm deep and characterised by an open porous network of 50 to 150 micrometres which are mechanically robust upon hydration. Firstly, the study was conducted using a batch adsorption method from a starting concentration 0.48 mM (100 mg/l) of Pb2+ in ultrapure water over 240 min, n = 4 with controls. A second series of experiments compared the adsorption of different competing ions at different valencies (Na+, Ca2+, Cu2+, La3+) in an equivalent media. A third series of experiments explored Pb2+ desorption from the aerogel at low pH and in highly acidic conditions. This simple filter system, based on a batch adsorption methodology expresses a high affinity for Pb2+ resulting in an ultra-high mean maximum adsorption capacity of 504 mg/g of Pb2+ within 240 mins at pH 5. The aerogel can also adsorb other toxic metal salts such as La3+ and Cu2+ with a capacity of 146 and 193 mg/g respectively. Furthermore, the aerogel structure can be acid washed removing 98% of the Pb2+ from the structure within three minutes. Overall, the data shows that GO alginate aerogels are highly effective at removing Pb2+ from water and the primary mechanism involved is ion exchange, although other phenomenon such as proton tunnelling may be a contributing factor to the ultra-high efficiency of the aerogel for Pb2+ remediation.


Assuntos
Água Potável/química , Grafite/química , Chumbo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Alginatos/química , Biopolímeros , Humanos , Troca Iônica
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