High-efficiency removal of methyl orange from wastewaters using polyimide/chitosan-MoS2-UiO-66 nanofiber adsorbents

Abstract

Abstract Conventional adsorbents such as chitosan and layered MoS 2 show promising functional groups or surface activity but suffer from intrinsic drawbacks such as limited surface area, and nanosheet aggregation, which restrict their efficiency in rapid dye removal. To overcome these limitations, we designed polyimide/chitosan-MoS 2 -UiO-66 (PI-CS-MoS 2 -UiO-66) nanofibrous adsorbents that integrate structural stability, abundant functional groups, and high porosity within a single hybrid system. The nanofibers were prepared by electrospinning PI as a robust support, followed by dip-coating with CS-MoS 2 -UiO-66 and crosslinking. XRD, BET, FT-IR, TGA, and SEM confirmed the successful incorporation of the composite. Adsorption tests on methyl orange (MO) showed strong dependence on pH, dosage, initial concentration, and temperature. The maximum adsorption capacity reached 195.61 $$\:\frac{\text{m}\text{g}}{\text{g}}$$ with excellent correlation to the Langmuir isotherm (R 2  = 0.9841). Thermodynamic parameters (ΔG < 0, ΔH < 0) indicated a spontaneous and exothermic process. Moreover, the adsorbent maintained good performance over three adsorption-desorption cycles, demonstrating reusability. These results demonstrate that combining PI, CS, UiO-66, and MoS 2 offers a synergistic platform that addresses the shortcomings of the individual components and enables high-efficiency dye removal from wastewater.