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Polymerin is a humic acid-like polymer, which we previously recovered for the first time from olive oil mill waste waters (OMWW) only, and chemically and physicochemically characterized. We also previously investigated its versatile sorption capacity for toxic inorganic and organic compounds. Therefore, a review is presented on the removal, from simulated polluted waters, of cationic heavy metals [Cu(II), Zn, Cr(III)] and anionic ones [Cr(VI)) and As(V)] by sorption on this natural organic sorbent in comparison with its synthetic derivatives, K-polymerin, a ferrihydrite-polymerin complex and with ferrihydrite. An overview is also performed of the removal of ionic herbicides (2,4-D, paraquat, MCPA, simazine, and cyhalofop) by sorption on polymerin, ferrihydrite, and their complex and of the removal of phenanthrene, as a representative of polycyclic aromatic hydrocarbons, by sorption on this sorbent and its complexes with micro- or nanoparticles of aluminum oxide, pointing out the employment of all these sorbents in biobed systems, which might allow the remediation of water and protection of surface and groundwater. In addition, a short review is also given on the removal of Cu(II) and Zn from simulated contaminated waters, by sorption on the humic acid-like organic fraction, named lignimerin, which we previously isolated for the first time, in collaboration with a Chilean group, from cellulose mill Kraft waste waters (KCMWW) only. More specifically, the production methods and the characterization of the two natural sorbents (polymerin and lignimerin) and their derivatives (K-polymerin ferrihydrite-polymerin, polymerin-microAl(2)O(3) and -nanoAl(2)O(3), and H-lignimerin, respectively) as well as their sorption data and mechanism are reviewed. Published and original results obtained by the cyclic sorption on all of the considered sorbents for the removal of the above-mentioned toxic compounds from simulated waste waters are also reported. Moreover, sorption capacity and mechanism of the considered compounds on polymerins and lignimerins are evaluated in comparison with other known natural sorbents, especially of humic acid nature and other organic matter. Some of their technical aspects and relative costs are also considered. Finally, the possible large-scale application of the considered sorption systems for water remediation is briefly discussed.

A dark and complex metal polymeric organic mixture, named polymerin, was recovered from olive oil mill wastewaters (OMWW) and characterized by chemical analysis, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and atomic absorption spectrometry (AAS). Polymerin proved to be composed of carbohydrates (52.40 mg 100(-1), w/w), melanin (26.14 mg 100(-1)), and proteins (10.40 mg 100(-1)), and the respective composition of monosaccharides, phenols, and amino acids was determined. It also contained metals (11.06 mg 100(-1)), mainly K(+) and, to a lesser extent, Na(+), Ca(2+), Mg(2+), Zn(2+), Fe(3+), and Cu(2+), which were naturally bound and chelated through carboxylate anions and other characteristic nucleophilic functional groups naturally occurring in polymerin. The distribution of polymerin relative molecular size was assessed to be approximately between 500.0 and 2.0 kDa by calibrated molecular weight gel filtration chromatography, indicating also that a fraction consisted of protein, melanin, and polysaccharide, strongly aggregated to each other in a supramolecular status by a combination of covalent and hydrogen bonds and CH/Pi interactions, and another fraction of only free polysaccharide. Polymerin was transformed into a potassium salt deglycosylated derivative, named KSDpolymerin, which was also characterized by chemical analysis, DRIFTS, and AAS. KSDpolymerin consisted of carbohydrates (6.00 mg 100(-1)), melanin (52.49 mg 100(-1)), and proteins (35.40 mg 100(-1)), and the composition of monosaccharides, phenols, and amino acids was determined. It also contained metals (6.11 mg 100(-1)), mainly K(+) and to a lesser extent Na(+), Ca(2+), Mg(2+), Zn(2+) and Fe(3+), bound as in polymerin. All the organic components were strongly linked in a supramolecular aggregate status and the relative average molecular size proved to be 6.3 kDa. Finally, we briefly discuss the possible use of such polymerins in agriculture as bioamendments and macro- and microelement biointegrators and as a biofilter for toxic metal removal, in light of their similarity with humic acids.