Carbon nitride photoactivation evaluation and degradation of a mixture of parabens by ozone assistance

Graphitic carbon nitride was investigated as an efficient and cheap catalyst for the degradation of a mixture of parabens through photo-aided processes. The ozone and g-C3N4 system was explored to obtain lacking necessary information regarding this combination for the proposed contaminants. The influence of key parameters was investigated to better understand the behavior of system and optimize it. Ultraviolet-A radiation promoted a more efficient activation of g-C3N4 compared to visible light. The photocatalytic ozonation process achieved higher parabens degradation rates and lower ozone consumption than the single technologies, reducing its overall cost. Basic and neutral conditions (pH = 7-11) promoted a better interaction between catalysts and contaminants, and radicals' formation. A catalyst concentration of 500 mg L-1 and parabens concentration of 1 mg L-1 resulted in >95 % removal of the three parabens within 15 min and with a lower transferred ozone dose required. Toxicity towards Allivibrio fischeri bacteria demonstrated a significant decrease in its luminescence inhibition after photocatalytic ozonation treatment, resulting in a non-toxic solution.