RESUMEN
This study developed a new α-Fe2O3 (hematite) nanoparticles-loaded spherical biochar (H-SB) through the direct pyrolysis of glucose-derived spherical hydrochar and FeCl3. The optimal impregnation ratio (hydrochar and FeCl3) was 1/1.25 (wt/wt). H-SB was applied to remove paracetamol (PRC) from water. Results indicated that H-SB exhibited a relatively low surface area (127 m2/g) and total pore volume (0.089 cm3/g). The presence of iron particles in its surface was confirmed by scanning electron microscopy with energy dispersive spectroscopy. The dominant form of iron nanoparticles (α-Fe2O3) in its surface was confirmed by X-ray powder diffraction and Raman spectrum. The crystallite size of α-Fe2O3 in H-SB was 27.4 nm. The saturation magnetization of H-SB was 6.729 cmu/g. The analysis of Fourier-transform infrared spectroscopy demonstrated that the C-O and O-H groups were mainly responsible for loading α-Fe2O3 nanoparticles in its surface. The adsorption study indicated the amount of PRC adsorbed by H-SB slightly decreased within solution pH from 2 to 11. The adsorption reached a fast saturation after 120 min. The Langmuir maximum adsorption capacity of H-SB was 49.9 mg/g at 25 °C and pH 7.0. Ion-dipole interaction and π-π interaction played an important role in adsorption mechanisms, while hydrogen bonding and pore filling were minor. Therefore, H-SB can serve as a promising material for treating PRC-contaminated water streams. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available in the online version of this article at 10.1007/s11814-021-1013-z.
RESUMEN
In this study, biochar derived from spent coffee grounds (SCGB) was used to adsorb norfloxacin (NOR) in water. The biochar properties were interpreted by analysis of the specific surface area, morphology, structure, thermal stability, and functional groups. The impacts of pH, NOR, and ion's present on SCGB performance were examined. The NOR adsorption mode of SCGB is best suited to the Langmuir model (R2 = 0.974) with maximum absorption capacity (69.8 mg g-1). By using a Response Surface Method (RSM), optimal adsorption was also found at pH of 6.26, NOR of 24.69 mg L-1, and SCGB of 1.32 g L-1. Compared with biochars derived from agriculture such as corn stalks, willow branches, potato stem, reed stalks, cauliflower roots, wheat straw, the NOR adsorption capacity of SCGB was 2-30 times higher, but less than 3-4 times for biochars made from Salix mongolica, luffa sponge and polydopamine microspheres. These findings reveal that spent coffee grounds biochar could effectively remove NOR from aqueous solutions. Approaching biochar derived from coffee grounds would be a promising eco-friendly solution because it utilizes solid waste, saves costs, and creates adsorbents to deal with emerging pollutants like antibiotics.