Adsorption of uranium (VI) from aqueous solutions using boron nitride/polyindole composite adsorbent

Abstract

Turbostratic boron nitride (tBN) surface is modified with polyindole (PIn) by a facile polymerization technique and the uranyl adsorption efficiency of this mesoporous hybrid is investigated. The successful surface modification is confirmed by FT-IR, Raman, XRD, TEM, SEM, EDX, EDS mapping XPS, BET, and zeta potential techniques. The batch experiments are performed in various temperatures (T), contact times (t), pH, and initial solution concentrations (C0) to evaluate its adsorption performance. The optimum adsorption performance is achieved at pH = 5.0–5.5, T = 307 K, t = 10 min, C0 = 18 mg L−1. These experimental results are evaluated using Freundlich, Redlich–Peterson, and Langmuir isotherm models, which presents equivalent regression coefficients. Maximum adsorption capacity (qm) of the nanoadsorbent (tBN/PIn), determined by the Langmuir isotherm, is 315.29 mg g−1. The adsorption kinetics of uranyl ions on tBN/PIn are in harmony with the pseudo-second order model. tBN/PIn nanoadsorbent provides high adsorption efficiency even at exceptionally low UO22+ concentration range (4–40 mg L−1) and low adsorbent mass (0.005 g). XPS analysis results show that 0.05% of uranium is adsorbed on tBN/PIn via mainly U-O coordination. The results of present study demonstrate that tBN/PIn can a potential adsorbent for removing uranium from aqueous solutions.