Insight into the adsorption of doxycycline hydrochloride on different thermally treated hierarchical CoFe2O4/bio-silica nanocomposite

[Display omitted] •Synthesis and calcination of novel CoFe2O4/bio-silica nanocomposite.•Adsorption mechanism of doxycycline (DOX) not limited to electrostatic interaction.•Energy-filtered-TEM (EFTEM) and TGA analysis confirmed the adsorption of doxycycline hydrochloride.•Adsorption capacity of 835.47 mg g−1 was obtained by the as-prepared nanocomposite.•DOX-loaded adsorbent was desorbed by thermal treatment. The removal of doxycycline hydrochloride (DOX), a widely used antibiotic, from wastewater by novel CoFe2O4/rice husk silica nanocomposite was studied. The adsorbent was synthesized through co-precipitation of iron and cobalt salt mixed with a solution of rice husk silica, whose precipitate was dried in an oven at 100 °C and calcined at 300, 500 and 700 °C. Characterization of the adsorbents showed that calcination did not affect their morphology, although the specific surface area and diffractogram of the nanocomposite were significantly affected at calcination temperature of 700 °C. The as-prepared nanocomposite has the highest surface area (283 m2 g−1). The adsorption studies revealed that the synthesized nanocomposite is an excellent material for the removal of DOX. The mechanism of adsorption entails electrostatic and n- π interaction. Adsorption data fitted well with Langmuir isotherm, having the monolayer adsorption capacity of 835.47 and 581.44 mg g-1 for the as-prepared and sample calcined at 700 °C, respectively. The removal of DOX is entropy driven, spontaneous in nature and confirmed by TGA and EFTEM analysis.