Synthesis, characterization, and sorption capacity of layered double hydroxides and their complexes with polymerin.

Mg−Al layered double hydroxides (LDHs) containing chloride (LDH−Cl) or carbonate (LDH−CO3) in the interlayer were obtained at room temperature and after calcitation at 450 °C (LDH−Cl-450 and LDH−CO3-450) and were characterized by X-ray diffraction and Fourier transform infrared analyses. Sorption isotherms of a humic acidlike fraction naturally occurring in olive oil mill waste waters, named polymerin, on these LDH minerals were carried out. Because LDH−CO3 showed the highest capacity to sorb polymerin among the four LDH minerals synthesized, two organo−mineral complexes named LDH−CO3−LP (low polymerin) and LDH−CO3−HP (high polymerin) were prepared by coprecipitation (LDH−CO3−LP) and sorption onto a preformed LDH−CO3 mineral (LDH−CO3−HP). These complexes were characterized chemically and physicochemically, and their stability to pH and after thermal treatment at 80 °C were evaluated. The diffuse reflectance infrared Fourier transform and X-ray analysis of the complexes indicated that polymerin was sorbed ...