Additively manufactured photoreactor with immobilized thermoset acrylic-graphitic carbon nitride nanosheets for water remediation: Response surface methods and adsorption modelling studies

In present work, graphitic carbon nitrite (g-CN) homojunction was synthesized and coated onto 3D-printed photoreactor for the removal of Rhodamine B (RhB) dye. The photocatalysis and adsorption experiments were investigated for 6 h under visible light irradiation and in the dark, respectively. The experimental parameters were flow rate of dye solution (1.0 – 3.0 mL/min), initial dye concentration (5.0 – 15.0 ppm), and number of photoreactors (2 – 6). The adsorption mechanisms were subsequently evaluated using isotherm and kinetics modelling. Redlich-Peterson (R-P) model showed the best fitted result with a relatively high coefficient value (R² = 0.9908) followed by Langmuir isotherm model (R² = 0.9822). The separation factor (R_L) has revealed that the adsorption process is favourable (R_L = 0.05). Besides, the adsorption experimental result is approaching the pseudo-second-order kinetics model (R² = 0.9898). The dye removal under light irradiation were investigated using 15 sets of experiments designed by Box-Behnken design. A second order-regression equation was developed to assess the performance of dye degradation. The predicted response is in good agreement with the experimental response, with deviation less than 3.50 %. In this case, the regression analysis concluded that the significance of the single effect followed the order of: number of photoreactor (p = 0.000) > flow rate of dye solution (p = 0.051) > dye initial concentration (p = 0.649). Besides, the analysis of variance (ANOVA) study showed that the interactions between parameters were insignificant. In short, the development of g-CN homojunction photocatalyst has provided an innovative approach for environmental remediation, in particular wastewater management.