One-step synthesis of nitrogen-grafted copper-gallic acid for enhanced methylene blue removal
Shella Permatasari Santoso, Vania Bundjaja, Artik Elisa Angkawijaya, Chintya Gunarto, Alchris Woo Go, Maria Yuliana, Phuong Lan Tran‐Nguyen, Chang‐Wei Hsieh, Yi‐Hsu Ju
Abstract
Abstract Nitrogen-grafting through the addition of glycine (Gly) was performed on a metal- phenolic network (MPN) of copper (Cu 2+ ) and gallic acid (GA) to increase its adsorption capacity. Herein, we reported a one-step synthesis method of MPN, which was developed according to the metal–ligand complexation principle. The nitrogen grafted CuGA (N g -CuGA) MPN was obtained by reacting Cu 2+ , GA, and Gly in an aqueous solution at a molar ratio of 1:1:1 and a pH of 8. Several physicochemical measurements, such as Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), N 2 sorption, X-ray diffraction (XRD), and thermal gravimetry analysis (TGA), were done on N g -CuGA to elucidate its characteristics. The analysis revealed that the N g -CuGA has non-uniform spherical shaped morphology with a pore volume of 0.56 cc/g, a pore size of 23.25 nm, and thermal stability up to 205 °C. The applicational potential of the N g -CuGA was determined based on its adsorption capacity against methylene blue (MB). The N g -CuGA was able to adsorb 190.81 mg MB per g adsorbent at a pH of 6 and temperature of 30 °C, which is 1.53 times higher than the non-grafted CuGA. Detailed assessment of N g -CuGA adsorption properties revealed their pH- and temperature-dependent nature. The adsorption capacity and affinity were found to decrease at a higher temperature, demonstrating the exothermic adsorption behavior.