Performance of metal free g-C3N4 reinforced graphene oxide bio-composite for the removal of persistent dyes

Abstract

Graphitic carbon nitride/graphene oxide (g-C₃N₄@GO/ Carboxy methylcellulose) based bio-composite was prepared, characterized and tested for the degradation of toxic dyes. Cellulose was extracted from coconut coir/spathe through acid hydrolysis and ultrasonication method. Followed by modification using the carboxymethylation process and subsequently loaded with graphene oxide and g-C₃N₄. The prepared carboxy methylcellulose (CMC), g-C₃N₄@GO, g-C₃N₄@GO/CMC biocomposite were analyzed by Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM) with energy dispersive X-ray analysis (EDX), X-ray diffractometer (XRD) and thermogravimetric analyzer (TGA). The photocatalytic activity of synthesized biocomposite was investigated for the degradation of basic green 4 (BG 4) and basic blue 9 (BB 9) dyes from aqueous solution using batch experiments under sunlight irradiation. The percentage of degradation of BG4 and BB9 was 94 and 98% under sunlight irradiation for 60 and 50 min in basic medium respectively. The photodegradation process is well described by the Langmuir- Hinshelwood and pseudo-first-order kinetic models. From the active species trapping experiment, it was found that the hole (h⁺), superoxide radical (O₂^·−), and hydroxyl radical (OH^.) played a significant role in the degradation of dyes and a possible degradation path is discussed with the results obtained from LC-MS. Moreover, the biocomposite showed higher stability and reusability for the degradation of dyes upto five cycles. Thus, the prepared g-C₃N₄@GO/CMC biocomposite can serve as a sustianable material in the current scenario for removing dyes.