In this work, the removal of Cu(II) ions from an aqueous effluent was studied using an Mg/Fe layered double hydroxide (LDH) as the adsorbent. The material was synthesized and characterized before and after the adsorption process to identify structural and morphological changes induced by copper uptake. Techniques such as X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), ultraviolet-visible spectroscopy (UV-Vis), Raman spectroscopy, and nitrogen physisorption (BET) were employed to confirm the interaction between the metal ions and the LDH surface. The LDH-Mg/Fe exhibited a high maximum adsorption capacity of 526 mg/g, and the adsorption kinetics followed a pseudo-second-order model, achieving over 90% removal of Cu(II) within 2.5 h. The Cu(II)-loaded material was subsequently evaluated as a sustainable catalyst in two applications: (i) an organic synthesis via “click” chemistry, reaching yields of up to 85%, and (ii) the decoloration of Congo Red via a Fenton-like process, achieving a decoloration efficiency of at least 84%. These dual uses demonstrate the potential of Cu(II)-loaded LDH as a cost-effective and environmentally friendly approach to simultaneous pollutant removal and catalytic valorization.

This study investigates the influence of divalent metals—(Mg(II), Co(II), and Ni(II)) in layered double hydroxides (LDHs), with a constant trivalent Fe(III) component—on the decoloration of crystal violet and methyl blue dyes via a Fenton-type oxidation reaction. The catalysts, synthesized by co-precipitation and hydrothermal treatment, were tested in both hydroxide and oxide forms under varying agitation conditions (0 and 280 rpm). A 2² × 3 factorial design was used to analyze the effect of the divalent metal type, catalyst phase, and stirring. The Mg/Fe oxide, with the highest BET surface area (144 m²/g) and crystallite size (59.7 nm), showed superior performance—achieving up to 98% decoloration of crystal violet and 97% of methyl blue within 1 h. The kinetic analysis revealed pseudo-second-order and pseudo-first-order fits for crystal violet and methyl blue, respectively. These findings suggest that LDH-based catalysts provide a fast, low-cost, and effective option for dye removal in aqueous systems.

Layered double hydroxides (LDHs) remain an interesting class of materials due to their applications in various chemical processes. LDHs can be synthesized using different techniques; however, simple methods for their production and for reducing energy consumption are still being explored. Ni/Fe LDHs are particularly interesting due to their usefulness in reactions for the treatment of contaminated aqueous effluents. For this reason, in this research, an ultrasound-assisted synthesis methodology of Ni/Fe LDHs was studied, compared with the conventional hydrothermal technique, and their relevant characteristics were compared. It was demonstrated that ultrasound-assisted LDH synthesis is a viable technique.

The persistence of fluoroquinolone antibiotics in aquatic environments represents a growing environmental concern and requires efficient and scalable treatment strategies. In this study, ciprofloxacin degradation was investigated through persulfate activation by using Ni-based layered double hydroxides (LDHs). NiFe-LDHs with different molar ratios (1:1, 2:1, and 3:1) were synthesized and compared with NiAl-LDH to elucidate the role of the trivalent metal in the catalytic performance. A 22 factorial design was employed to evaluate the influence of the catalyst dosage and persulfate volume. All catalysts exhibited rapid removal, reaching approximately 57% removal within 20 min and up to 87% removal after 120 min. Increasing the Ni content did not improve the overall removal performance, indicating that activity is not directly governed by the amount of Ni present. Kinetic analysis followed pseudo-second-order behavior, while factorial results indicated that catalyst dosage had a stronger influence than the persulfate concentration. Mass spectrometry confirmed the disappearance of the parent ion (m/z 332), indicating an effective transformation of ciprofloxacin. Radical scavenger experiments indicated a greater contribution of radical species in the Fe-containing materials, whereas NiAl-LDH showed a more adsorption-driven removal pathway. No synergistic enhancement between Ni and Fe was observed, as NiAl-LDH exhibited comparable or superior performance despite containing the non-redox-active Al3+ center. Density functional theory (DFT) calculations revealed that Ni centers play a dominant role in persulfate activation, whereas the trivalent metal primarily modulates the electronic structure and the reaction pathway of the catalyst. These findings challenge the conventional assumption that the presence of multiple redox-active metal centers necessarily enhances the catalytic performance in LDH systems and highlight the critical role of the local electronic environment in designing efficient catalysts for environmental applications.

This study investigates the application of a layered double hydroxide (LDH) catalyst modified with Cu(II) ions for the decolorization of Congo red. HDLs have a layered structure that makes them well-suited as catalysts in chemical processes. To evaluate the catalytic performance of Cu-HDL Mg/Fe, the decolorization of Congo red dye was studied using the Fenton process with conventional stirring and ultrasound-assisted agitation. It was demonstrated that ultrasound radiation enhanced the oxidation process by improving the dispersion of the reactants, accelerating the activation of H₂O₂ and decolorization, increasing efficiency, and reducing treatment time. A 94% decolorization was achieved with an ultrasonic bath in just 2 hours of treatment, contributing to the study of eliminating organic contaminants from water.

Water pollution represents a growing environmental problem. Among the most relevant contaminants are synthetic dyes, which are discharged into water bodies due to inadequate treatment of industrial effluents. In this work, the adsorption kinetics of violet crystal dye were studied using a mixed oxide Mg/Fe, derived from a laminar double hydroxide (HDL) Mg/Fe. Likewise, the adsorption efficiency of the dye was evaluated by varying the contact time and temperature. The results showed a removal of at least 58.49%, reaching a maximum of 99.01%.