Nitrogen doping induced by intrinsic defects of recycled polyethylene terephthalate-derived carbon nanotubes

The indiscriminate utilization of nondegradable polyethylene terephthalate(PET)-based products has triggered serious environmental pollution that has to be resolved vigorously.A simple synthesis of N-doped carbon nanotubes from recycled PET(NCNTs_(r-PET))was developed by a nitric acid-assisted hydrothermal method.Experimental results and theoretical calculations show that the intrinsic defects in CNTs_(r-PET)would induce N-doping by NH_(3)generated from nitric acid during the hydrothermal process,thus producing the NCNTs_(r-PET).The life cycle assessment proves that the developed method for N-doped CNTs using r-PET as the carbon source is more environmentally friendly than the conventional chemical vapor deposition using acetylene as the carbon source.As a typical application,the NCNTs_(r-PET)delivered an impressive sodium storage capacity with an ultralong lifespan.This work not only provides a new route to upcycling waste plastics into valuable carbonaceous materials in an ecofriendly manner,but also reveals a basic understanding of the N-doping mechanism in carbonaceous materials.

Influence of recycled polyethylene terephthalate fibres on plastic shrinkage and mechanical properties of concrete

Polyethylene terephthalate bottles production has drastically increased year after year due to high versatility of polyethylene terephthalate plastics and considerable consumption of beverages.In tandem with that increase,the major concern of society has been the improper disposal of this non-biodegradable material to the environment.To deal with this concern,recycled polyethylene terephthalate bottles were incorporated in concrete as fibre reinforcements in this study.The objective of this research is to evaluate the mechanical properties of recycled polyethylene terephthalate fibre reinforced concrete(RPFRC)in comparison with control concrete without fibres.polyethylene terephthalate fibres with three different diameters(0.45,0.65,and 1.0 mm)and two lengths(20 and 30 mm)were added at various proportions(0.5%,1.0%,1.5%and 2.0%)by volume of concrete in order to determine the effect of fibres initially on compressive,flexural and splitting tensile strengths of concrete.The results revealed that none of the fibres have detrimental effects up to 1%volume fraction,however further addition caused slight reductions on mechanical properties in some conditions.Plastic shrinkage resistance and impact resistance tests were also performed according to related standards.Polyethylene terephthalate fibres were observed to have marked improvements on those properties.Such a good performance could be attributed primarily to the bridging effect of fibres.