One-step statistical design of experiment for the screening and optimization of magnetite nanoparticles yields from solvothermal synthesis

Abstract

One-step custom design of experiment was employed for the simultaneous screening and optimization of raw yield (Y 1 ) and percent yield (Y 2 ) with heating temperature, T (190–220 °C) and reaction time, t (1.0–2.5 h) as the predictors in a conventional solvothermal magnetite nanoparticles (NPs) synthesis. Two accurate models capable of explaining 98.3% variability in the data were developed. A strong correlation exists between the actual yields (Y 1 , Y 2 ) and their predicted counterparts (r = 0.99). T, t, Tt and t 2 terms have a significant synergistic effect on the yields the at α = 0.05. The diagnostic plots depicted the effects in the order t > T > Tt > t 2 . Surface and contour plots show maximum Y 1 (0.295 g) and Y 2 (105%) at T = 219 °C and t = 2.5 h. The optimizer plot shows maximized Y 1 (109.94%) and Y 2 (0.31 g) at the highest predictor values (T = 220 °C, and t = 2.5 h) at composite desirability of 1. NPs characterization using various techniques revealed nanocubes and nanospheres with a mean diameter of 23.9 ± 7.9 nm, the crystallite size of 8.3 ± 1.4–20.4 ± 4.9 nm, a pore size of 9.07–24.47 nm, and surface area of 35.80–93.57 m 2 g −1 . The NPs exhibit stretching Fe–O vibrations at 571 cm −1 for tetrahedral and at 428 cm −1 for octahedral geometries in the infrared spectra and are thermally stable within the range 30–700 °C with low weight loss (8.81–32.92%) typical of mesoporous magnetite phase. • Response models explain 98% variability in the 16.4-nm mean sized Fe 3 O 4 NPs yields. • Diagnostic charts depict the significance of time and temperature effects on yields. • Fe 3 O 4 NPs yields are maximized at 220 °C, 2.5 h and composite desirability of one. • Most Fe 3 O 4 NPs samples exhibit H1 hysteresis loop and Type IV adsorption isotherm.