Synthesis and characterization of new composite from modified silica-coated MnFe2O4 nanoparticles for removal of tetracycline from aqueous solution

Abstract

In this study, a new composite from silica coated MnFe₂O₄ nanoparticles, diethylenetriamine, 3-chloropropyl trimethoxysilane and Mg–Al Layered Double Hydroxide (Mg–Al LDH/DETA/CPTMS/SCNPs) composite was synthesized. The Mg–Al LDH/DETA/CPTMS/SCNPs composite was examined by Fourier transform infrared spectrometer (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDS), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA) and Vibrating Sample Magnetometry (VSM). The synthesized composite exhibited magnetic property with a saturation magnetization of 0.40 emu g⁻¹. The Mg–Al LDH/DETA/CPTMS/SCNPs composite was utilized as a successful adsorbent for removal of tetracycline from aqueous solutions. The effect of various operation factors such as initial drug concentration, adsorbent dosage, pH and contact time were investigated. The optimized variable conditions such as adsorbent dose of 60 mg L⁻¹, drug concentration of 100 mg L⁻¹, pH = 7 and contact time 30 min were obtained. For describing the adsorption isotherms, the Langmuir, Freundlich and Temkin adsorption models were utilized. The results indicated that the adsorption isotherm is in good agreement with Langmuir model. According to the Langmuir analysis, the maximum adsorption capacity (q_m) of the Mg–Al LDH/DETA/CPTMS/SCNPs composite for tetracycline was obtained to be 40.16 mg g⁻¹. The kinetic studies revealed that the adsorption in all cases to be a pseudo second-order process. The negative value of ΔG° and the positive value of ΔH° showed the adsorption process to be spontaneous and endothermic.