Preparation of Lanthanum-Modified Tea Waste Biochar and Its Adsorption Performance on Fluoride in Water

Abstract

In this study, tea waste was used as a raw material, and TBC (tea waste biochar) was prepared by pyrolysis at 700 °C. La(NO3)3·6H2O was used as the modifier to optimize one-way modification; the orthogonal experiment was undertaken to determine the optimal preparation conditions; and La-TBC (lanthanum-modified biochar) was obtained. The key factors for the adsorption of fluoride by La-TBC were investigated by means of batch adsorption experiments, and kinetics and isothermal adsorption experiments were carried out on the adsorption of fluoride in geothermal hot spring water. The adsorption mechanism of fluoride by La-TBC was analyzed via characterization methods such as SEM-EDS (Scanning Electron Microscope and Energy Dispersive Spectrometer), BET (Brunauer–Emmett–Teller), FTIR (Fourier transform infrared), XRD (X-ray diffraction), and so on. The results show that La-TBC had the best adsorption effect on fluoride at pH 7. The process of adsorption of fluoride follows the pseudo-second-order kinetics and Langmuir isothermal model, and the maximum theoretical adsorption quantity was 47.47 mg/g at 80 °C, while the removal rate of fluoride from the actual geothermal hot spring water reached more than 95%. The adsorption process was dominated by the monolayer adsorption of chemicals, and the mechanisms mainly include pore filling, ion exchange, and electrostatic interaction.

Comparative Study for Propranolol Adsorption on the Biochars from Different Agricultural Solid Wastes

“…Igwegbe et al found that the adsorption efficiency of wheat straw biochar for nitrogen (N) in ammonium chloride solution (NH 4 Cl) reached 95.08%, and the removal of N from landfill leachate by wheat straw biochar was 26.67 mg·g −1 [ 23 ]. Li et al prepared biochar from tea waste at 700 °C and found that biochar was effective in adsorbing fluoride from aqueous solutions, with removal rates of more than 95% from the actual geothermal hot spring water [ 24 ]. Therefore, the adsorption properties of biochar made from different raw materials are different, so it is necessary to study the adsorption effect of different biochars.…”