Simultaneous removal of Pb2+ and direct red 31 dye from contaminated water using N-(2-hydroxyethyl)-2-oxo-2H-chromene-3-carboxamide loaded chitosan nanoparticles

Abstract

This study reports the preparation of a new material that can remove synthetic dyes and trace metals simultaneously. A new coumarin derivative was synthesized and its chemical structure was inferred from spectral data (FT-IR, ¹H-NMR, ¹³C-NMR). Meanwhile, chitosan nanoparticles (CsNPs) were prepared then used as a carrier for two different concentrations of the coumarin derivative (C1@CsNPs and C2@CsNPs). The TEM, SEM and DLS findings illustrated that the prepared nanocomposites exhibited spherical shape and small size (less than 200 nm). The performance of the prepared material for the removal of an anionic dye (direct red 31, DR31) and cationic trace metal (Pb²⁺) was evaluated in unary and binary systems. The results revealed that complete removal of 10 mg L⁻¹ of DR31 and Pb²⁺ in unary system was achieved at pH_o 3.0 and 5.5 using 0.5 and 2.0 g L⁻¹, respectively, of C2@CsNPs. The adsorption of DR31 and Pb²⁺ followed different mechanisms as deduced from the effect of pH_o, kinetic, isotherm and binary adsorption studies. The adsorption of DR31 followed the Langmuir isotherm model and the pseudo-first-order kinetic model. While, the adsorption of Pb²⁺ followed Freundlich isotherm model and Elovich kinetic model. In the binary system, the co-presence of DR31 and Pb²⁺ did not affect the adsorption of each other's. Overall, the prepared material showed promising results for the removal of anionic dyes and cations trace metals from contaminated water.