Effect of calcination temperature, pH and catalyst loading on photodegradation efficiency of urea derived graphitic carbon nitride towards methylene blue dye solution

In this study, the photodegradation of methylene blue (MB) dye was performed using urea based graphitic carbon nitride (g-C3N4). Interestingly, it has been observed that the calcination temperature for the synthesis of g-C3N4 along with factors (pH and catalyst loading) influencing the photodegradation process, can make an impactful improvement in its photodegradation activity towards MB dye solution. The concept behind the comparatively improved photoactivity of g-C3N4 prepared at 550 degrees C was explored using various characterisation techniques like XRD, FTIR, SEM, BET and DRS. The FTIR and XRD patterns demonstrated that synthesis of g-C3N4 took place properly only when the calcination temperature was above 450 degrees C. The evolution of morphological and optical properties based on calcination temperature led to dramatically increased BET surface area and a decreased optical band gap value of g-C3N4 prepared at 550 degrees C. The effects of pH conditions and catalyst concentration on the MB dye degradation rate using optimally synthesised g-C3N4 are discussed. The value of the apparent rate constant was found to be 12 times more in the case of photodegradation of the MB dye using g-C3N4 prepared at 550 degrees C at optimum pH and catalyst loading conditions when compared with g-C3N4 prepared at 450 degrees C showing the lowest photoactivity potential. Further, high stability of the photocatalyst was observed for four cyclic runs of the photocatalytic reaction. Hence, g-C3N4 can be considered as a potential candidate for methylene blue photodegradation.