Dual-group functionalized self-floating adsorbent based on hollow glass microspheres for removal of diclofenac sodium and Moxifloxacin: Synthesis, performance and mechanism.

Emerging contaminants in aquatic environments pose undeniable hazards, among which residual anti-inflammatory drugs and antibiotics are particularly prominent ecological threats that have attracted widespread attention. In this study, via a simple two-step process, the organic monomer dimethyloctadecyl[3-(trimethoxysilyl)propyl] ammonium chloride (QC18) was grafted onto hollow glass microspheres (HGM), leading to the synthesis of a dual-group functionalized self-floating adsorbent (HGM@QC18) for pharmaceutical removal. Comprehensive characterization of HGM@QC18 was conducted using techniques including SEM, XPS, and FTIR. The adsorption performance of HGM@QC18 towards diclofenac sodium (DS) (as the model anti-inflammatory drug) and moxifloxacin (MOX) (as the model antibiotic) was systematically investigated under different conditions such as adsorption contact duration, system temperature, initial pollutant dosage, solution pH, and the concentration of coexisting ions. The results demonstrated that the D-R and Langmuir models matched the adsorption isotherms of DS and MOX, respectively, with the maximum capacities for adsorption of DS and MOX reaching 278.0 and 244.9 mg g-1. The PSO model proved applicable for describing the adsorption processes of the two contaminants. After five adsorption-desorption cycles, HGM@QC18 exhibited a 19% and 23% decline in its capacity to remove DS and MOX, respectively. Mechanistic analyses verified that electrostatic attraction, hydrogen bonding, and hydrophobic interaction are the key interactions involved in the adsorption process. With high adsorption efficiency and self-floating separation, HGM@QC18 shows notable potential as a viable solution for reducing emerging contaminant-related pollution in the environment.