Facile fabrication of phosphorylated alkali lignin microparticles for efficient adsorption of antibiotics and heavy metal ions in water

The development of low-cost, high-efficienct, and environmentally benign adsorbents for the removal of antibiotics and heavy metal ions in water is greatly needed. Phosphorylated alkali lignin (PAL) microparticles were newly fabricated via a facile one-pot method. The characterization confirmed that the phosphate group was successfully introduced into the lignin matrix, and the specific surface area of the obtained PAL was 9.53 m2·g-1, 5.6 times that of lignin (1.71 m2·g-1). The adsorption behavior of PAL was initially investigated in a batch mode by using levofloxacin hydrochloride (LH) as a model. PAL performance was then validated to other contaminants as Pb(II), tetracycline (TC), and sulfadiazine (SA). The results indicated that 99.91% of LH (C0=80 mg·L-1) could be removed by PAL (0.02 g/50 mL) within 80 min. The adsorption capacity of PAL to LH and Pb(II) reached 389.1 mg·g-1 and 349.2 mg·g-1, respectively, better than earlier adsorbents. Importantly, PAL had a strong ability to remove the complex pollutants with coexisted Pb(II) and LH in water and was also applicable for adsorption of TC and SA. XPS and FTIR results show that the adsorption is mainly related to π-π stacking, hydrogen bonds and electrostatic interaction. The adsorption amount of LH in fixed-bed column was 240.5 mg·g-1 and removal percentage of LH and Pb2+ in real wastewater was above 90% and 70% which indicated the great application potential.