ADSORPTION AND FIXATION OF VANADIUM IN SOIL BY SEPIOLITES MODIFIED BY ACID-THERMAL ACTIVATION, SULFHYDRYL ORGANISATION AND HYDROXYL IRON-ALUMINUM PILLARING

The effects of acid-thermal activation, sulfhydryl organisation and hydroxyl iron-aluminum pillaring modified sepiolite as adsorbent to fix V(Ⅴ) in soil were studied. Batch adsorption tests were carried out to investigate the effects of adsorbent addition, adsorption time, and initial V(Ⅴ) concentration on adsorption. The Langmuir and Freundlich isothermal adsorption curves were used to explore the adsorption effect and mechanism of soil system added with modified sepiolite on V(Ⅴ). The results showed that after modification the specific surface area of sepiolite increased, the structure changed, and the adsorption capacity enhanced. The maximum adsorption amount of hydroxyl iron-aluminum pillaring modified sepiolite (F-SEP), acid-thermal activation (H-SEP), and sulfhydryl organisation (S-SEP) applied soils were 2159.71, 1619.57, 936.57 mg/kg, respectively. The adsorption of V(Ⅴ) in soil by modified sepiolite was a single molecular layer physical adsorption. The desorption test showed that S-SEP had the highest desorption rate, while the desorption rate of F-SEP and H-SEP was lower. The H-SEP and F-SEP had better adsorption effect on V(Ⅴ) in soil than S-SEP, when the dosage was 5%, their solidification rate was 30.24% and 22.67%, respectively. Thus, sepiolite modified by acid-thermal activation, sulfhydryl organisation and hydroxyl iron-aluminum pillaring could be used as potential adsorbent for the treatment of vanadium polluted soils, but the stability of F-SEP still needs to be improved.