Facile synthesis of MgO/ZnO nanocomposite for efficient removal of alizarin red S dye from aqueous media

The prevalence of dyes in aquatic environments raises severe concerns on a global scale. Alizarin red s dye can result in dangerous impacts on the health of humans that involve digestive system problems, skin and eye irritation, somnolence, breathing disorders, and blood clotting. So, in this work, MgO/ZnO nanocomposite with a low crystal size and high surface area was facilely produced by the Pechini sol-gel method using tartaric acid as a complexing agent and propylene glycol as a crosslinker for the first time. The scanning electron microscope (SEM) exhibited that the MgO/ZnO nanocomposite consists of semi-spherical particles with an average diameter of about 73.82 nm. Moreover, the energy-dispersive X-ray spectroscopy (EDS) analysis clearly demonstrated that the synthesized MgO/ZnO nanocomposite consists of Mg, Zn, and O with weight percentages equal to 24.83, 58.92, and 16.25 %, respectively. The average crystal size (D) of the MgO/ZnO nanocomposite is 67.37 nm. Also, the Brunauer, Emmett and Teller (BET) surface area of the MgO/ZnO nanocomposite is 141.51 m2/g. Moreover, in an acidic medium, the high surface area of the synthesized nanocomposite renders the surface of the MgO/ZnO nanocomposite highly positively charged, enabling it to effectively attract and remove anionic alizarin red s dye through electrostatic interaction. The maximum adsorption capacity (Q) of the MgO/ZnO nanocomposite towards alizarin red s dye is 378.79 mg/g. Besides, pH equals 2, contact time equals 90 min, and temperature equals 298 K are considered the ideal conditions for achieving the maximum elimination percentage (% E = 90.74) by mixing 0.05 g of the MgO/ZnO nanocomposite with 100 mL of a 200 mg/L alizarin red s dye solution. Moreover, the elimination of alizarin red s dye on the MgO/ZnO nanocomposite is spontaneous, exothermic, chemical, and more accurately described by the pseudo-second-order model and Langmuir isotherm. Furthermore, the MgO/ZnO nanocomposite can be used many times to get rid of the alizarin red s dye without affecting its efficiency.