A comprehensive factorial design study of variables affecting CaCO₃ scaling under magnetic water treatment

Magnetic water treatment (MWT) could be an interesting alternative to chemical treatment to prevent scaling and has been used as an antiscaling treatment for domestic and industrial equipment. A two level-three factor (2³) full factorial design was used to evaluate the effects of pH (6–7.5), flow rate (0.54–0.94) and application of a magnetic field on the induction time (IT), total precipitation (TP) rate and homogeneous precipitation (HP) rate of calcium carbonate (CaCO₃) scale from hard water. The experimental results and statistical analysis show that the pH, flow rate and interaction between pH and magnetic field have negative effects on IT response. In the case of TP rate response, the magnitude of the main influence is attributed to the magnetic field, followed by pH value and their interaction. Flow rate and pH value have a negative effect on HP rate response, but their interaction has a positive effect. Within these factor ranges, these studied responses predicted by the models were in good agreement with the experimental values. The coefficient of determination (R²) for reduction time, TP ratio and HP ratio were 97.8%, 99.12% and 99.92%, respectively. These results were analyzed statistically using Minitab 15.