Interfacial interactions between plastic particles in plastics flotation

•The EDLVO profiles were calculated to examine interparticle interactions.•The dominant force between plastic particles is hydrophobic attraction.•Selective adsorption of wetting agents improves flotation separation of plastics.•Increasing the polarity of solid surface reduces hydrophobic attraction...

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Bibliographic Details
Published in:Waste management (Elmsford) 2015-12, Vol.46, p.56-61
Main Authors: Wang, Chong-qing, Wang, Hui, Gu, Guo-hua, Fu, Jian-gang, Lin, Qing-quan, Liu, You-nian
Format: Article
Language:English
Subjects:
Attraction
Dispersions
Flotation
Gibbs function
Hydrophobic and Hydrophilic Interactions
Hydrophobic attraction
Interfacial interactions
Mathematical analysis
Models, Theoretical
Particulate Matter - chemistry
Plastics - chemistry
Plastics flotation
Polymers
Refuse Disposal
Surface chemistry
Surface energy
Water Pollutants, Chemical - chemistry
Wetting agents
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Summary:•The EDLVO profiles were calculated to examine interparticle interactions.•The dominant force between plastic particles is hydrophobic attraction.•Selective adsorption of wetting agents improves flotation separation of plastics.•Increasing the polarity of solid surface reduces hydrophobic attraction. Plastics flotation used for recycling of plastic wastes receives increasing attention for its industrial application. In order to study the mechanism of plastics flotation, the interfacial interactions between plastic particles in flotation system were investigated through calculation of Lifshitz–van der Waals (LW) function, Lewis acid–base (AB) Gibbs function, and the extended Derjaguin–Landau–Verwey–Overbeek potential energy profiles. The results showed that van der Waals force between plastic particles is attraction force in flotation system. The large hydrophobic attraction, caused by the AB Gibbs function, is the dominant interparticle force. Wetting agents present significant effects on the interfacial interactions between plastic particles. It is found that adsorption of wetting agents promotes dispersion of plastic particles and decreases the floatability. Pneumatic flotation may improve the recovery and purity of separated plastics through selective adsorption of wetting agents on plastic surface. The relationships between hydrophobic attraction and surface properties were also examined. It is revealed that there exists a three-order polynomial relationship between the AB Gibbs function and Lewis base component. Our finding provides some insights into mechanism of plastics flotation.
ISSN:0956-053X
1879-2456
DOI:10.1016/j.wasman.2015.08.041