Study on adsorption properties of yttrium on corn straw biochar loaded hydroxyapatite

As a high abundance rare earth element, yttrium is widely used in various fields. In the mining process of ion-type rare earth, rare earth mother liquor will diffuse to the water body around the mining area, resulting in the waste of rare earth resources. To find an efficient material for absorbing rare earth yttrium, biochar (BC) was fired from corn straw and loaded with hydroxyapatite to prepare biochar composite material (HAP@BC). HAP@BC was characterized with SEM, XRD and FTIR. Single-factor adsorption experiments were conducted to investigate the effects of initial Y³⁺ concentration, biochar dosage, pH, rotational speed and adsorption temperature on adsorption properties. Adsorption isotherms were used to analyze its adsorption characteristics, and desorption experiments were conducted to investigate its recycling performance. The results show that compared to BC, the adsorption capacity of HAP@BC has increased by three times, with a maximum adsorption capacity of 333.83 mg/g at pH 4.0. The adsorption process conforms to Langmuir monolayer adsorption model, and HAP@BC has good recycling performance, which is a potential Y³⁺ high-efficiency adsorbent.