Extreme pH-tolerant FeOOH@NiAl-LDH nanohybrid adsorbents: Ultra-stable dye adsorption driven by multiple synergistic mechanisms and potent antibacterial performance

Abstract

The discharge and accumulation of organic dyes in the environment have become pressing issues that require urgent attention. Layered double hydroxides (LDH) based adsorbents are emerging as a promising potential for treating wastewater contaminated with difficult-to-remove organic dyes. However, single LDH adsorbents still face serious challenges in practical applications, including low adsorption capacity, poor structural stability, and a narrow pH range. Here, we employed a simple hydrothermal method to fabricate a 3D flower-like structure of FeOOH hybridized nickel-aluminum LDH (FeOOH@NiAl-LDH). The FeOOH derived from MOF-235 possesses a higher specific surface area and pore volume, which provides more adsorption sites and pore space, effectively enhancing the adsorption performance of Congo red (CR). Meanwhile, the interaction between FeOOH and NiAl-LDH enhances the structural stability of the adsorbent, endowing it with efficient adsorption and reproducibility under strongly alkaline conditions, thus achieving a dual enhancement in adsorption capacity (1297.0 mg/L) and stability under extreme pH (2−12) conditions. Additionally, the assessments for antibacterial activity and cytotoxicity confirms that FeOOH@NiAl-LDH exhibits excellent antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Overall, this study not only provides new insights into the application of LDH in the field of water treatment but also offers important theoretical foundations for the design and preparation of high-performance dye adsorption materials.