How to effectively deal with the polluted water by the pollutant of organic dyes is the world problem. It is of great significance if the organic dyes in the polluted water can be directly turned into the useful materials through a facile approach. Herein, the water which contains the common organic dye, Reactive red 2 (RR2), has been chosen to be the model to synthesize graphene quantum dots (GQDs) by a facile route. The comprehensive characterizations, including TEM (HRTEM), XPS, Raman, PL and UV–Vis. spectra, have been performed to confirm the structures and explore the properties of the synthesized GQDs. Meanwhile, the excellent PL properties and low biotoxicity of the GQDs confer them with the potential applications in the biological fields. When the GQDs are excited by the wavelength of 360 nm, the maximum emission is achieved at 428 nm. It is well demonstrated that the synthesized GQDs are able to detect the Al3+ which causes multiple diseases, such as Parkinson, Alzheimer, kidney disease, and even cancer. The detection range is from 90 to 800 μM, which is different from the reported kinds of the literature. Therefore, this work not only provides an economical and environmental route on solving the universal problem from organic dyes, but also facilitates to advancing the synthesis and application of GQDs.

Synthesis of graphene quantum dots from organic dye for the biosensor application
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Chemical reagents
        2.2 The route for dealing with the polluted water
        2.3 Characterizations
        2.4 Selective detection of Al3+
    3 Results and discussion
        3.1 Structural characterization of GQDs.
        3.2 The application of GQDs for detection of Al3+
    4 Conclusion
    Acknowledgements 
    References

• Qiuyan Li(College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, Analysis and Testing Center, China Three Gorges University, Yichang 443002, Hubei, China)
• Jinrun Fu(College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, Analysis and Testing Center, China Three Gorges University, Yichang 443002, Hubei, China)
• Weifeng Chen(College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, Analysis and Testing Center, China Three Gorges University, Yichang 443002, Hubei, China, Hubei Three Gorges Laboratory, Yichang 443002, Hubei, China)
• Fatao Zhang(College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, Analysis and Testing Center, China Three Gorges University, Yichang 443002, Hubei, China)
• Jie Cao(College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, Analysis and Testing Center, China Three Gorges University, Yichang 443002, Hubei, China)
• Xiang Liu(College of Materials and Chemical Engineering, Key Laboratory of Inorganic Nonmetallic Crystalline and Energy Conversion Materials, Analysis and Testing Center, China Three Gorges University, Yichang 443002, Hubei, China, Hubei Three Gorges Laboratory, Yichang 443002, Hubei, China)