“…Four methods were considered for response surface modelling: Box-Behnken design (BBD), central composite design (CCD), full factorial design (FFD), and D-optimal design (DOD). Thus, model equations (4), (5), (6), and (7) are associated with fractional factorial method (FRFDRSMs), model equations (8), (9), (10), and (11) are associated with Placket-Burman method (PBDRSMs), and the 2 feasible response model equations (12) and (13) are associated with screening using one variable at-a-time (OVAATRSMs). Tables 6, 7, and 8 show the constants in all the equations:…”