Facilitated physisorption of ibuprofen on waste coffee residue biochars through simultaneous magnetization and activation in groundwater and lake water: Adsorption mechanisms and reusability

Abstract

The adsorption of ibuprofen (IBU) onto the pristine (CB), magnetic (MCB), and simultaneously magnetic activated waste coffee residue biochars (MACB) in groundwater and lake water was rigorously investigated in order to offer profound insights into the differences in their adsorption mechanisms and performances (i.e., adsorption capacity and separability). The higher adsorption capacity of IBU for MACB compared CB and MCB in groundwater and lake water was mainly attributed to the well-developed micropore structures of MACB via the simultaneous magnetization and activation. These phenomena were pronounced for groundwater than lake water due to its lower dissolved organic carbon concentrations. The calculated kinetic, intra-particle diffusion, isotherm, and thermodynamic parameters indicate that the adsorption of IBU onto CB, MCB, and MACB proceeded spontaneously and endothermically and their adsorption processes in groundwater and lake water were mainly governed by the physisorption (i.e., pore-filling effects, hydrogen bonding, and 7C-7C electron donoracceptor interactions), liquid film diffusion, and intra-particle diffusion. The noticeable increase of the X-ray photoelectron spectroscopy peak intensity related to the C--O bond of the carbonyls in IBU-loaded MACB suggests that the accelerated pore-filling effects via the simultaneous magnetization and activation lead to the adsorption capacity improvement of IBU in groundwater and lake water. From the superior reusability of MACB in 3-4 adsorption-desorption cycles even under real water matrices (reuse efficiency > 60%), it can be postulated that the simultaneous magnetization and activation might provide a practicable way for enhancing the adsorption capacity of IBU toward waste coffee residue biochars and their separability in groundwater and lake water.