Lanthanun oxide (La₂O₃) is a lanthanum chemical compound incorporates a sensible anionic complexing ability; however, it lacks stability at a low pH scale. Biochar fibers will give the benefit of their massive space and plethoric uses on the surface to support a metal chemical compound. Herein, wet spinning technology was used to load La³⁺ onto sodium alginate fiber, and to convert La³⁺ into La₂O₃ through carbonization. The La₂O₃-modified biochar (La-BC) fiber was characterized by SEM, XRD and XPS, etc. An adsorption experiment proved that La-BC showed an excellent adsorption capacity for chromates, and its saturation adsorption capacity was about 104.9 mg/g. The information suggested that the adsorption was in step with both the Langmuir and Freundlich models, following pseudo-second-order surface assimilation mechanics, which showed that the Cr (VI) adsorption was characterized by single-phase and polyphase adsorption, mainly chemical adsorption. The thermodynamic parameters proved that the adsorption process was spontaneous and endothermic. The mechanistic investigation revealed that the mechanism of the adsorption of Cr (VI) by La-BC may include electrostatic interaction, ligand exchange, or complexation. Moreover, the co-existing anions and regeneration experiments proved that the La-BC is recyclable and has good prospects in the field of chrome-containing wastewater removal.

Enteromorpha prolifera, a marine solid waste abundantly available in Asia, was used as a low-cost precursor to prepare activated carbon (EPAC) using pyrophosphoric acid, H₄P₂O₇, as a chemical activating agent. The effects of impregnation ratio, activation temperature and activation time on the specific surface area of the activated carbon were investigated through response surface methodology. The optimum preparation conditions were described as follows: impregnation ratio, 1.26; activation temperature, 455°C; activation time, 48 min. The characteristics of EPAC were examined by nitrogen adsorption–desorption isotherms, Fourier transformed infrared spectroscopy and scanning electron microscopy. The total pore volume and specific surface area of EPAC under optimum conditions were identified as 1.365 cm³/g and 1124.1 m²/g. The EPAC possessed high BJH pore volume, 1.276 cm³/g and methylene blue value, 330 mg/g, indicating the existence of abundant mesopores. The adsorption kinetic data of ciprofloxacin were well fitted to pseudo-second-order model, displaying a monolayer adsorption capacity for CIP of 216.55 mg/g. The equilibrium data can be well described by Langmuir model. The dominant sorption mechanism is electrostatic attraction.