Efficient Rhodamine B dye uptake onto MgZrO3@g-C3N4 nanostructures: Fabrication and adsorption mechanism

Abstract

Pristine graphitic carbon nitride (g-C3N4) was synthesized by calcination of urea under elevated temperature. A blend of g-C3N4 nanosheets and nanosized ZrO2 and MgO precursors were used to prepare MgZrO3@g-C3N4 hybrid nanocomposite (MZCN) then it was assessed for the adsorption of Rhodamine B (RhB) dye from aqueous solution. The X-ray diffraction analysis revealed the development of the monoclinic ZrO2, cubic MgO, and hexagonal graphitic carbon nitride phases. The energy diffraction X-rays (EDX), photoelectron electron, and Fourier transformed infrared (FT-IR) spectroscopy analyses collectively validated the formation of the presumed composite. An improved porosity with a surface area 35.86 m2.g−1 and pore volume 0.087 cm3.g−1 were determined by N2 adsorption setup. The adsorption kinetics fitted well with the pseudo-first-order model (R2 > 0.99), which designated an adsorption process influenced by physisorption. The kinetics models investigations revealed a film diffusion control of the adsorption process. The adsorption equilibrium matched perfectly with the Langmuir isotherm model (R2 > 0.99) marking a maximum adsorption capacity of 370.8 mg g−1, demonstrating outstanding monolayer adsorption process. In addition, the Freundlich constant (n = 1.76) value is falling in the range 1–10 suggested a favorable adsorption of RhB onto the composite surface. The mechanistic enquiry suggested van der Waal, hydrogen bonds and π–π electron–donor interactions between the electron-rich RhB and the functional groups in the adsorbent’s molecule. This work stipulates that MgZrO3@g-C3N4 holds promise as efficient adsorbent for organic dyes from contaminated wastewater.