The natural diatomite was treated with NaOH to obtain alkali-activated diatomite. The materials were systematically characterized by X-ray powder diffraction, X-ray fluorescence, Fourier transform infrared spectroscopic, scanning electron microscopy, and N2 adsorption–desorption. Meanwhile, the potential use of alkali-activated diatomite as adsorbent for the removal of basic fuchsin from aqueous solution was assessed by batch experiment. Results indicated that the structure and textural properties of diatomite were obviously changed via alkali activation, and then affecting its adsorption performance. The adsorption capacity of alkali-activated diatomite for basic fuchsin was higher than that of natural diatomite. In the case of alkali-activated diatomite, its adsorption capacity was increased with increasing the activation temperature, and the diatomite activated at 115°C (alkali-activated diatomite-115) exhibited the maximum adsorption capacity. The pseudo-first-order kinetics and the Sips isotherm model were preferable to describe the adsorption process of basic fuchsin on alkali-activated diatomite-115 and the thermodynamic parameters indicated that the adsorption process was endothermic and spontaneous.

Background Most dyes are toxic, carcinogenic, and mutagenic, all of which cause severe harm to human health and the environment. Therefore, it is essential to find the most suitable method to treat dye wastewaters before discharge. In this study, the natural Ca‐type montmorillonite (Ca‐MMT) was activated by HNO3 (20 wt.%) solution under different temperatures to obtain acid‐activated MMT (Acid‐MMT). Fe (10 wt.%) was supported on Acid‐MMT (Fe/Acid‐MMT) via the impregnation method using Fe(NO3)3·9H2O as a precursor. Meanwhile, the removal of methylene blue (MB) by heterogeneous Fenton‐like reaction using Fe/Acid‐MMT as catalyst was evaluated. The material was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), X‐ray photoeletron spectroscopy (XPS), scanning electron microscopy (SEM), N2 adsorption–desorption at low temperature, and the temperature program desorption of NH3 (NH3‐TPD) techniques. Results The acidity and textural properties of the Acid‐MMT were adjusted by varying the acid activation temperature. Moreover, the amount of acidity and the surface area of the catalyst had a noticeable effect on the removal efficiency of MB. Fe‐supported Acid‐MMT activated by HNO3 at 100°C (Fe/Acid‐MMT‐100) catalyst exhibited the highest removal efficiency of MB. The removal efficiency of the MB was more than 97.8% under the following reaction conditions: H2O2 concentration of 0.85 mmol·L−1, Fe/Acid‐MMT‐100 dosage of 0.75 g°L−1, temperature of 50°C, and initial solution pH of 3.0–9.0. Conclusion An efficient Fe/Acid‐MMT catalyst for a Fenton‐like reaction was obtained by optimizing the acid treatment temperature of Ca‐MMT. The synergistic effect between its excellent adsorption ability and the ∙OH generated from H2O2 activated by Fe/Acid‐MMT would enhance MB removal efficiency in a Fenton‐like system. © 2022 Society of Chemical Industry (SCI).

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