The influence of ZnO nanoparticles amount on the optimisation of photo degradation of methyl orange using decorated MWCNTs

In the current study, we want to optimise the removal efficiency of methyl orange using decorated multi-walled carbon nanotubes (MWCNTs) with different amount of ZnO nanoparticles. For this purpose, we investigate the influence of several parameters such as UV irradiation time, pH of the solution and weight fraction of photocatalysts on the removal efficiency using 2-level factorial design. The statistical analysis results using Half-normal plot demonstrate that all of the main factors have a significant effect on the removal efficiency of pollutant. Meanwhile, the results of t test and Pareto charts reveal that UV irradiation time and weight fraction have a positive effect on the responses. However, the influence of pH on the removal efficiency of methyl orange is negative. The results of the optimisation process show that for maximising the removal efficiency of pollutant, the optimal level of irradiation time, pH and weight fraction should set to 25 min, 4 and 0.5 %wt, respectively.