LAUSR

Abstract Different types of humic acid (HA) were extracted from black soil and sediments and their influence on the regeneration and reusability of hydrocalumite (calcium -LDHs, Ca-LDH) were studied. The results showed that the regeneration of Ca-LDH after calcination (Ca-CLDH) required the shortest time to reconstruct in HA solution, and dissolution-reprecipitation was the main process responsible for the structure memory effect of Ca-LDH. In addition, metal ions were released from the sample complexed with HA, which indicates that HA plays an important role in the regeneration process. The crystal size of LDHs regenerated in HA solutions were smaller than that in deionized water. Surface area, pore size and volume of regenerated Ca-LDH decreased in the HA solution. New Ca-LDH was decomposed to release Ca2+ ions and formed CaCO3 with CO32− in deionized water. Differently, the formation of CaCO3 in HA solution was inhibited. During the recycle use for removal of bisphenol A (BPA) through calcination method, Ca-LDH was converted to CaCO3 in the absence of HA and the adsorption ability was decreased evidently. However, in the presence of HA, Ca-CLDH could transform into layered structure and maintain its adsorption performance. This is because the presence of HA has an influence on the structure regeneration of Ca-LDH, especially inhibiting the transformation of LDH into CaCO3.