Fabrication of poly (quinine- co-itaconic acid) incorporated reduced graphene oxide nanocomposite and its application for electrochemical sensing and photocatalysis of hydroquinone

In this work, we report the synthesis of poly (quinine-co-itaconic acid) incorporated graphene oxide composite that is electro-active and photo-active simultaneously. The poly (quinine-co-itaconic acid)@rGO composite was successfully utilized for electrochemical detection and photocatalytic degradation of hydroquinone (HQ). HQ is recognized as an environmental pollutant because of its high toxicity to human health even at low concentrations. The synthesized composite was characterized using different characterization techniques i.e. Fourier Transform Infrared Spectroscopy (FTIR), Energy Dispersive X-ray Spectroscopy (EDX), Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD), Brunauer-Emmett-Teller (BET) and zeta potential. The characterization studies revealed the net negative surface charge of -17.6 mV for poly (quinine-co-itaconic acid)@rGO composite that confirms its stability. Moreover, the XRD and FTIR studies confirmed the fabrication of poly (quinine-co-itaconic acid)@rGO composite. The electrochemical properties of synthesized composite were determined via cyclic voltammetry and electrochemical impedance spectroscopy which showed high conductivity and charge transfer kinetics. Under optimized condition, the sensor showed excellent response for hydroquinone i.e. potential window from -0.6 to 0.6 V at scan rate 50 mV s^-1 and borate buffer of pH 8 as supporting electrolyte. The developed method was comprehensively validated and found linear between 0.1 to 40 μM of HQ, with limit of detection 0.03 μM and limit of quantification 0.1 μM, respectively. The real water and personal care products samples were used to check the applicability of developed sensor and good percent recovery was achieved. The synthesized poly (quinine-co-itaconic acid)@rGO composite was also utilized for photocatalytic degradation of HQ and the degradation efficiency was obtained as 99% with dosage of 0.5 g L^-1 under optimized conditions such as solution pH 7, initial concentration of HQ 10 mg L^-1, catalyst dosage of 5 mg and irradiation time of 40 min, respectively. The degradation efficiency of poly (quinine-co-itaconic acid)@rGO composite was also evaluated in real water samples from industry and river.