Preparation of biochemical fulvic acid‐modified diatomite and its adsorption characteristics for tetracycline in water

Abstract

AbstractBACKGROUNDDiatomite and biochemical fulvic acid were used as raw materials to prepare biochemical fulvic acid‐modified diatomite using by the sol–gel method. The structure and properties of samples were investigated by X‐ray diffraction, scanning electron microscopy, etc. The effects of solution pH and reaction temperature on the adsorption performance of adsorption materials were evaluated by taking tetracycline as the target pollutant. The adsorption kinetics, adsorption rate mechanism and adsorption isotherm of tetracycline were revealed.RESULTSThe results showed that the main form of diatomite is amorphous SiO2. The surface and channels of diatomite were loaded with biochemical fulvic acid, and the specific surface area of the modified material increased from 9.182 to 13.774 m2 g−1, while the average pore size decreased from 10.972 to 7.15 nm. The pH of the tetracycline solution was 5 and the initial concentration was 20 mg L−1; the adsorption capacity of the modified sample increased 1.93‐fold to 29.84 mg g−1. When the adsorption temperature was increased from 10 to 60 °C, the adsorption capacity of the modified material increased nearly fourfold, reaching 78.8 mg g−1.CONCLUSIONQuasi‐second‐order reaction kinetics has a correlation coefficient R2 of 0.993, which suggests a good fit to the adsorption process of tetracycline by the modified diatomite. Both Freundlich and Redlich–Peterson adsorption isotherm equations can elucidate the adsorption process of the composites. The adsorption is heterogeneous adsorption on the surface, mainly multi‐layer adsorption and electrostatic attraction adsorption. © 2022 Society of Chemical Industry (SCI).