Clustered flower-like Mg/Al/Fe-LDHs-based material for highly efficient Fenton degradation of crystal violet wastewater

Abstract

In this study, a ternary hydrotalcite of Mg/Al/Fe/SDBS-LDHs was synthesized via a hydrothermal method, utilizing sodium dodecyl benzene sulfonate (SDBS) as a modifier. The prepared Mg/Al/Fe/SDBS-LDHs were characterized using FT-IR, SEM, XRD, TG, BET, ESR and XPS techniques. The CV removal process was monitored and analyzed using UV–vis spectroscopy, DFT and LC-MS methods. The results demonstrated that the Mg/Al/Fe/SDBS-LDHs exhibited a clustered, flower-like structure with irregular pores, which facilitated CV removal. Under optimal conditions, the degradation rate of Mg/Al/Fe₁/SDBS-LDHs (500 °C, 2 h) reached 99.3 % at a molar ratio of Mg:Al:Fe = 1:3:1. Moreover, the maximum CV removal capacity increased to 963 mg/g upon the addition of 0.1 mL H₂O₂. The influence of various factors on CV removal, including the initial solution pH, reaction temperature, and coexisting ions, was systematically examined. DFT calculations reveal that in the optimized molecular structure of CV, the carbon atoms C1, C2, C5, and C7 are highly susceptible to be attacked by hydroxyl radicals (·OH). LC-MS and UV–vis analyses revealed that CV degradation generated (4-aminophenyl) (p-tolyl) methanone,4-aminobenzoic acid, and 4-aminophenol, which were subsequently mineralized into CO₂ and H₂O. This work presents a novel approach to the degradation of high-concentration printing and dyeing wastewater using hydrotalcite, highlighting its potential application for actual wastewater treatment.