Magnetic coffee residue as sorbent for magnetic solid-phase extraction and determination of titanium dioxide nanoparticles in water samples

Herein, we report a simple, efficient, and cost-effective solid-phase extraction method using magnetic coffee residue as adsorbent for extraction and determination of titanium dioxide nanoparticles (TiO2 NPs) from environmental water samples. The adsorbent was prepared by modifying spent coffee residue using magnetite nanoparticles as magnetic medium through modified chemical precipitation technique, and the TiO2 NPs were synthesized by a sol-gel method. The prepared materials were characterized by X-ray diffractometry, scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. Factors affecting the extraction conditions were optimized, including effect of pH (4), sample volume (25 mL), amount of adsorbent (0.075 g), vortexing time (3 min), initial concentration (70 mg L-1) and the desorption conditions. Under optimum conditions, the developed method exhibited high extraction efficiency (94%), a wide linear range (100-500 mu g L-1) and a limit of detection (LOD) of 12 mu g L-1. Moreover, the method showed excellent intra- and inter-day precision, with relative standard deviations (% RSD) of 3.47% and 4.58%, respectively. More importantly, the current method demonstrated great potential for the extraction and quantification of TiO2 NPs in river, lake and effluent water samples and exhibited good percentage recovery. Therefore, the developed method can be used for monitoring level of TiO2 NPs in different sample matrices. [GRAPHICS] .

Automated summary

In this study, a solid-phase extraction method using magnetic coffee residue as adsorbent was developed for extraction and determination of TiO2 NPs. The method showed high extraction efficiency, a wide linear range, and good precision and recovery. These results demonstrate the potential of this method for monitoring TiO2 NPs levels in different sample matrices.