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. Here, an extreme pH-tolerant 3D flower-like microsphere adsorbent with potent antibacterial performance, FeOOH hybridized nickel–aluminum layered double hydroxide (FeOOH@NiAl-LDH), is fabricated by a simple hydrothermal method. The FeOOH@NiAl-LDH adsorbent possesses a higher specific surface area (117.115 m² g⁻¹) and pore volume (0.607 cm³ g⁻¹), which provides more adsorption sites and pore space, effectively enhancing the adsorption performance of Congo red (CR). The results of the adsorption show that the maximum theoretical adsorption capacity of FeOOH@NiAl-LDH reaches 1297.0 mg g⁻¹, much higher than that of NiAl-LDH (500 mg g⁻¹). Importantly, 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. The adsorbent removed more than 96% of CR over a wide range of pH 2–12, and the adsorption rate is still as high as 86% even after five regeneration cycles, overcoming the disadvantages of poor stability and narrow applicable pH of NiAl-LDH. Furthermore, the assessments for antibacterial activity and cytotoxicity confirm that FeOOH@NiAl-LDH exhibits excellent antibacterial activity, with inhibition rates of 99.5% and 98.2% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. 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.