Comparison of the Surface Properties of Hydrothermally Synthesised Fe(3)O(4)@C Nanocomposites at Variable Reaction Times

The influence of variable reaction time (t(r)) on surface/textural properties (surface area, total pore volume, and pore diameter) of carbon-encapsulated magnetite (Fe(3)O(4)@C) nanocomposites fabricated by a hydrothermal process at 190 °C for 3, 4, and 5 h was studied. The properties were calculated using the Brunauer–Emmett–Teller (BET) isotherms data. The nanocomposites were characterised using Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetry, and scanning and transmission electron microscopies. Analysis of variance shows t(r) has the largest effect on pore volume (F value = 1117.6, p value < 0.0001), followed by the surface area (F value = 54.8, p value < 0.0001) and pore diameter (F value = 10.4, p value < 0.001) with R(2)-adjusted values of 99.5%, 88.5% and 63.1%, respectively. Tukey and Fisher tests confirmed t(r) rise to have caused increased variations in mean particle sizes (11–91 nm), crystallite sizes (5–21 nm), pore diameters (9–16 nm), pore volume (0.017–0.089 cm(3) g(−1)) and surface area (7.6–22.4 m(2) g(−1)) of the nanocomposites with individual and simultaneous confidence limits of 97.9 and 84.4 (p-adj < 0.05). The nanocomposites’ retained Fe–O vibrations at octahedral (436 cm(−1)) and tetrahedral (570 cm(−1)) cubic ferrite sites, modest thermal stability (37–60 % weight loss), and large volume-specific surface area with potential for catalytic application in advanced oxidation processes.