Adsorption of gallic acid on nanoclay modified with poly(diallyldimethylammonium chloride)

Abstract

In this work, particles of nanoclay modified with poly(diallyldimethylammonium), PDDA, namely PDDA/PGV, were obtained and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), surface area measurement (BET surface area), measurement of zero charge point (pH_PCZ), and scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS). The PDDA/PGV particles were applied as adsorbent for the removal of gallic acid (GA) from aqueous solution. The effect of various parameters, such as solution pH, contact time, adsorbent mass, and temperature, was studied. The maximum adsorption capacity of PDDA/PGV (238.45 mg g⁻¹) was observed at pH 4 and 15 °C. The study of adsorption kinetics and isotherms revealed that the adsorption process was better fitted by pseudo-first order and Freundlich model, respectively. The obtained thermodynamic parameters indicate that the adsorption of GA is spontaneous and enthalpy-driven.

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