Polyvinylpyrrolidone-reduced graphene oxide was prepared by modified hummers method and was used as adsorbent for removing Cu ions from wastewater. The effects of contact time and ions concentration on adsorption capacity were examined. The maximum adsorption capacity of 1689 mg/g was observed at an initial pH value of 3.5 after agitating for 10 min. It was demonstrated that polyvinylpyrrolidone-reduced graphene oxide had a huge adsorption capacity for Cu ions, which was 10 times higher than maximal value reported in previous works. The adsorption mechanism was also discussed by density functional theory. It demonstrates that Cu ions are attracted to surface of reduced graphene oxide by C atoms in reduced graphene oxide modified by polyvinylpyrrolidone through physisorption processes, which may be responsible for the higher adsorption capacity. Our results suggest that polyvinylpyrrolidone-reduced graphene oxide is an effective adsorbent for removing Cu ions in wastewater. It also provides a new way to improve the adsorption capacity of reduced graphene oxide for dealing with the heavy metal ion in wastewater.

A facile chemical route to synthesize the graphene/melamine composite sponge with super oil adsorption capacity was reported. The effect of the graphene loading on the microstructures and adsorption property of the composite sponge was studied in detail. The adsorption capacity of diesel oil in composite sponge could reach 99.0 g/g. The oil adsorbed in composite sponge could be desorption in ethanol at 50°C. Furthermore, the composite sponge exhibited excellent mechanical and environmental stability. The facile production, high stability, high adsorption capacity and recycling makes this material practically useful for the treatment of oil pollution in future.

The FeCo/Fe3O4 nanocomposite was synthesized using the hydrothermal approach, in which the FeCo alloy and Fe3O4 are formed by one step. The structure of the FeCo/Fe3O4 nanocomposite was characterized by means of Scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray energy-dispersive spectrometer spectroscopy (EDX). They show that the mass ratio of FeCo/Fe3O4 strongly depends on the reaction temperature. Such various architectures follow a stepwise growth mechanism of the composites prepared in various reaction temperatures were also discussed. It indicates that this strategy is facile, effective and controllable for the synthesis of FeCo/Fe3O4 by the one-step method. Furthermore, the magnetic and wave-absorbing properties of the nanocomposites with various structures were investigated in detail. The results show that the FeCo/Fe3O4 with higher mass ratio has higher magnetic properties. Moreover, the FeCo/Fe3O4 nanocomposite shows high wave-absorbing properties (e.g., −37.9 dB), which are expected to apply in microwave absorbing materials.

Polycarboxylate superplasticisers (PCE) were synthesised and their structure was characterised by Fourier-transformed infrared spectroscopy. The simulated physiological environmental effects on the workability retention of cement paste containing PCE were studied; that is, stimuli response to sulfates by measuring the fluidity, waterreducing ratio, compressive strength and setting time. The fluidity and water-reducing ratio of cement paste containing PCE with a long chain weakly depended on the salt dosage, but properties of compressive strength and setting time were strongly influenced by the salt dosage. However, the fluidity, water-reducing ratio, compressive strength and setting time of cement containing PCE with both long and short chains were strongly influenced by alkaline sulfate. PCE with a long side chain has a good compatibility with cement paste. The ionic responsive properties are attributed to the change of the PCE adsorption ratio, which results directly in a variation of the dispersing force of superplasticiser.

Polyvinylpyrrolidone-reduced graphene oxide was prepared by modified hummers method and was used as adsorbent for removing Cu ions from wastewater. The effects of contact time and ions concentration on adsorption capacity were examined. The maximum adsorption capacity of 1689 mg/g was observed at an initial pH value of 3.5 after agitating for 10 min. It was demonstrated that polyvinylpyrrolidone-reduced graphene oxide had a huge adsorption capacity for Cu ions, which was 10 times higher than maximal value reported in previous works. The adsorption mechanism was also discussed by density functional theory. It demonstrates that Cu ions are attracted to surface of reduced graphene oxide by C atoms in reduced graphene oxide modified by polyvinylpyrrolidone through physisorption processes, which may be responsible for the higher adsorption capacity. Our results suggest that polyvinylpyrrolidone-reduced graphene oxide is an effective adsorbent for removing Cu ions in wastewater. It also provides a new way to improve the adsorption capacity of reduced graphene oxide for dealing with the heavy metal ion in wastewater.