Activated Carbon and Carbon Quantum Dots/Titanium Dioxide Composite Based on Waste Rice Noodles: Simultaneous Synthesis and Application in Water Pollution Control

To achieve the full utilization of waste rice noodle (WRN) without secondary pollution, activated carbon (AC) and carbon quantum dots/titanium dioxide (CQDs/TiO2) composite were simultaneously synthesized by using WRN as raw material. Both of the two materials showed potential applications in water pollution control. The AC based on WRN displayed a porous spherical micro-morphology, which could absorb heavy metal elements like Pb(II) and Cr(VI) efficiently, with a maximum equilibrium uptake of 12.08 mg center dot g(-1) for Pb(II) and 9.36 mg center dot g(-1) for Cr(VI), respectively. The adsorption of the resulted AC could match the Freundlich adsorption isotherm and the pseudo-second-order kinetics mode. On the other hand, the CQDs/TiO2 composite based on WRN displayed a high efficient photocatalytic degradation effect on various water-soluble dyes such as methylene blue, malachite green, methyl violet, basic fuchsin, and rhodamine B under visible light irradiation, which showed better photocatalytic performance than commercial TiO2. The introduction of CQDs based on WRN to TiO2 could result in efficient electron-hole pair separation and enable more photogenerated electrons to reduce O-2 and more photogenerated holes to oxidize H2O or OH-, which could cause stronger abilities in producing O-2(center dot-) and center dot OH radical and better photocatalytic activity.

Automated summary

Activated carbon and carbon quantum dots/titanium dioxide composite were successfully synthesized using waste rice noodle as raw material. Both materials showed potential applications in water pollution control. The activated carbon displayed efficient absorption of heavy metal elements, while the carbon quantum dots/titanium dioxide composite showed better photocatalytic degradation performance of water-soluble dyes under visible light irradiation.