Preparation of rhamnolipid-layered double hydroxide nanocomposite for removing p-cresol from water

Rhamnolipid (RL)-modified Mg3Al-layered double hydroxide (LDH) was prepared as p-cresol adsorbent by ion exchange (RL-LDH1) and delamination/reassembling (RL-LDH2) method, respectively. The basal spacing of RL-LDH1 (d003 = 3.22 nm) and RL-LDH2 (d003 = 3.39 nm) was significantly increased compared with Mg3Al LDH (d003 = 0.90 nm) due to the intercalation of RL anions between the LDH layers. The reduced surface area of RL-LDH nanocomposites demonstrated their strong hydrophobic property. The highest adsorption capacity of RL-LDH2 for p-cresol was intimately related to its stacking model of the interlayer hydrophobic moiety and higher RL (organic carbon) content. The linear model well fitted for p-cresol adsorption isotherms, implying a partitioning adsorption process. Along with the effect of temperature on p-cresol adsorption, an adsolubilization mechanism and an exothermic adsorption nature during adsorption process were revealed.