In situ synthesis of hierarchical structured cotton fibers/MnO2 composites: a versatile and recyclable device for wastewater treatment

Abstract

To improve the feasibility of MnO₂ nanoparticles for applications in wastewater treatment, cotton fibers–MnO₂ hierarchical composites (C-MHCs) were fabricated via a new and efficient two-step strategy. The as-prepared C-MHCs were characterized by FTIR, XPS, XRD, SEM and TEM analyses, and the results show that the C-MHCs possess hierarchical structure with a monolayer coverage of MnO₂ nanoparticles on the cotton fiber surfaces. The batch adsorption experiments were executed as a function of pH value, contact time and initial concentration. Adsorption behavior followed the pseudo-second-order model (R² > 0.99) and Langmuir isotherm, with Langmuir maximum adsorption capacity of 68.3, 174.2, 109.4 and 247.0 mg g⁻¹ for Cu²⁺, Pb²⁺, CR and MB, respectively. The regeneration experiments show that more than 85% of the initial adsorption amount was retained at the 5^th sequential adsorption–desorption cycle. Considering the simple and facile fabrication process, all-round adsorption feasibility and high-efficiency regeneration performance, the C-MHCs are believed to be a versatile and renewable candidate for wastewater treatment.