Hybrid organic-inorganic derivatives of layered double hydroxides and dodecylbenzenesulfonate: Preparation and adsorption characteristics

Layered double hydroxides (LDHs) are anionic clays that can be synthesized under laboratory conditions. In this study, different LDHs were synthesized by a coprecipitation method, with the parent products and calcined derivatives evaluated for their ability to adsorb the anionic surfactant, dodecylbenzenesulfonate (DBS). Adsorption isotherms for DBS retention on LDHs were typical L-type curves, with adsorption data conforming to a simple Langmuir equation. Langmuir maximum adsorption of DBS on calcined-LDH was significantly higher than that on uncalcined-LDHs. Organo-LDHs were also synthesized by incorporating DBS into LDHs via ion-exchange, reconstruction of calcined-LDH and in-situ synthesis methods. X-ray diffraction analysis of organo-LDHs revealed that DBS was intercalated into LDHs with the mono-layer DBS molecules oriented perpendicularly to LDH surfaces. Intercalation of DBS into LDHs decreased surface area according to BET analysis. The adsorption capacities of organo-LDHs for trichloroethylene (TCE) and tetrachloroethylene (PCE) were substantially greater than the original LDH materials. Adsorption of organic compounds by organo-LDHs was due to a partitioning mechanism.