title: Synthesis, characterization, and sorption capacity of layered double hydroxides and their complexes with polymerin.
abstract: Mg-Al layered double hydroxides (LDHs) containing chloride (LDH-Cl) or carbonate (LDH-CO(3)) in the interlayer were obtained at room temperature and after calcitation at 450 degrees C (LDH-Cl-450 and LDH-CO(3)-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-CO(3) showed the highest capacity to sorb polymerin among the four LDH minerals synthesized, two organo-mineral complexes named LDH-CO(3)-LP (low polymerin) and LDH-CO(3)-HP (high polymerin) were prepared by coprecipitation (LDH-CO(3)-LP) and sorption onto a preformed LDH-CO(3) mineral (LDH-CO(3)-HP). These complexes were characterized chemically and physicochemically, and their stability to pH and after thermal treatment at 80 degrees C were evaluated. The diffuse reflectance infrared Fourier transform and X-ray analysis of the complexes indicated that polymerin was sorbed only on the external surfaces of LDH-CO(3) and no intercalation occurred. The LDH-polymerin complexes appeared to be more stable than LDH-CO(3) at pH 4.0 and showed that they were able to sorb both As(V) and Zn. Because the waste waters are usually contaminated with mixtures of pollutants in cationic and anionic forms, the LDH-polymerin complexes appear more suitable than the sorbents in a potential water remediation process.
authors.affiliation: Dipartimento di Scienze del Suolo, della Pianta, dell'Ambiente e delle Produzioni Animali, Università di Napoli Federico II, Portici, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Iorio
authors.forename: Antonio
authors.initials: A
authors.lastname: De Martino
authors.forename: Antonio
authors.initials: A
authors.lastname: Violante
authors.forename: Massimo
authors.initials: M
authors.lastname: Pigna
authors.forename: Renato
authors.initials: R
authors.lastname: Capasso
mesh_terms: D006878:Hydroxides / Q000737:chemistry*; D011108:Polymers; D013054:Spectrophotometry, Atomic; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014961:X-Ray Diffraction
chemical_list: D006878:Hydroxides; D011108:Polymers