Experimental and modeling studies for adsorbing different species of fluoride using lanthanum-aluminum perovskite

We investigated the adsorption mechanisms for removing fluoride based on experimental and modeling studies. Lanthanum-aluminum perovskite was designed for treating wastewater contaminated by fluoride. A fluorine-species model was developed to calculate the concentrations of different species of fluorine: F-, HF, HF2-. Multiple kinetic models were examined and the pseudo-second order model was found the best to fit the experimental data, implying fast-chemisorption. The thermodynamic data were fitted by the Langmuir model and Freundlich model at different temperatures, indicating heterogeneous adsorption at low temperature and homogeneous adsorption at high temperature. The La2Al4O9 material had less influence from negative ions when adsorbing fluoride. The adsorption mechanisms were further studied using experiments and Density Functional Theory calculations. The adsorption experiments could be attributed to the lattice plane (1 2 1) and La, O, Al sites. More Al sites were required than La sites for the increase of fluoride concentration. By contrast, more La sites than Al sites were needed for increased pH. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The study investigated the adsorption mechanisms of lanthanum-aluminum perovskite for removing fluoride from wastewater. Experimental and modeling studies showed that the material had fast-chemisorption capabilities, with different adsorption behaviors at different temperatures. Experiments and Density Functional Theory calculations revealed that the adsorption process was attributed to specific lattice planes and metal sites on the material, providing insights into the adsorption mechanism.