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The production of olive oil is one of the main agricultural activities with a large amount of wastewater. So, the proper treatment of the olive mill wastewater (OMW) is superior for environmental-friendly industries and one of the most efficient and low-cost methods is the sorption of organic compounds. In the present work, palygorskite, a fibrous clay mineral, is proposed for this application as it exhibits high sorption capacity for the organic load (total organic carbon) in olive mill wastewater. The optimum sorption was observed for slightly acidic conditions (pH 4) and reached the sufficient value of 65%. The most efficient mass to volume ratio was 20 g/L and the sorption was completed in 30 min, while it was temperature independent. From this study palygorskite can be considered and further examined as a promising and cost-effective material for the pre-treatment of OMW concerning the removal of the organic compounds.

The employment of N-(2-carboxyphenyl)salicylideneimine in 4f metal chemistry has led to two families of dinuclear complexes depending on the lanthanide(III) used. Representative members exhibit interesting magnetic, optical, and catalytic properties.

Poly(N,N-dimethylacrylamide) hydrogel forms complexes with terpyridine and various trivalent ions, like Eu3, Tb3, Gd3, and In3. The hydrogel can be obtained in three different phases:  swollen with water, lyophilized (i.e., dried by freeze-drying), where it loses the solvent but preserves the swollen configuration, and dried in the air where it shrinks. The three hydrogel phases affect the type of complex formed between terpyridine and the metal ion. Thus, in the swollen and lyophilized phases, metal-centered emission can be obtained by energy transfer from the excited ligand. In the shrunk phase, an intense green fluorescence is emitted, which is ligand-centered and is independent of the complexed ion. In the absence of any ion, the ligand emits blue luminescence, independently of the hydrogel phase. In the presence of europium(III) ions, blue, green, or red emission can be thus produced at appropriate compositions and hydrogel phases. Analysis of the photophysical behavior of the polymer−ligand−metal ion complex is related with the photophysical behavior of the ligand and its complexes in various pure solvents.

Ureasils are nanocomposite organic−inorganic materials based on a silica backbone covalently connected through urea bridges with poly(oxyalkylene) chains. Ureasil gels are synthesized by the sol−gel procedure. These gels can efficiently adsorb and retain dyes from aqueous solutions and, thus, can be employed as water purification agents. Anionic dyes bearing a sulfonate chemical group are most efficiently adsorbed, followed by hydrophobic dyes and, finally, by cationic dyes. The adsorption of anionic dyes is very impressive, because a densely colored water sample is transformed into crystal clear water by using only a small quantity of ureasil adsorbent. Variations of the adsorption efficiency have been detected by varying the poly(oxyalkylene) chain length or by using different catalysts of the sol−gel procedure. The most efficient adsorbents were gels made by the conventional sol−gel route, that is, by HCl catalysis.

Summary.:  Transparent nanocomposite gels made of hybrid organic/inorganic polymers, synthesized through the sol-gel method, composed of poly-(ethylene oxide) or poly-(propylene oxide) chains, and grafted on silica through urea bridges, have been studied by steady-state and time-resolved photoluminescence techniques. These nanocomposite materials consist of two distinguished subphases, an organic and an inorganic one. The volume fraction of the organic (polyether) subphase is larger than that of the inorganic (silica) subphase, and it increases with increasing polyether chain size. The condensation of the silica subphase provides luminescent entities emitting light by electron-hole recombination on delocalized states associated with the active chemical species of the urea bridges. Materials with smaller polyether chains are more luminescent than such with longer polyether chains. Divalent or trivalent cations introduced into these materials enhance the luminescence intensity by solubilization close to the silica cluster surface and thus by decreasing surface defects and the ensuing quenching mechanism.

Thin surfactant films were made by dip-coating a fused-silica slide in reverse micelles of bis(2-ethylhexyl) sulfosuccinate sodium salt [AOT] in cyclohexane. The fluorescence quenching analysis of charge transfer between Ru(bpy)[formula]and MV2+, of resonance energy transfer between pyrene and coumarin-153, and of pyrene excimer formation has revealed that the original micellar structure is to a large extent transferred into the structure of the film. The film consists of a hydrophilic and a hydrophobic subphase. Nondried films contain entrapped cyclohexane which allows diffusion of the hydrophobic probes in the film and a rather random distribution of them. Drying leads to solvent evaporation and hydrophobic probe aggregation. The kinetics of the hydrophilic probes reflect the structure of the hydrophilic domain which is not affected by drying procedure. The above films are transparent matrices and make excellent hosts for photophysical studies.

Reactions of di(2-pyridyl) ketone, (py)2CO, with indium(III) halides in CH3NO2have been studied, and a new transformation of the ligand has been revealed. In the presence of InIII, the C═O bond of (py)2CO is subjected to nucleophilic attack by the carbanion –:CH2NO2, yielding the dinuclear complexes [In2X4{(py)2C(CH2NO2)(O)}2] (X = Cl, 1; X = Br, 2; X = I, 3) in moderate to good yields. The alkoxo oxygens of the two η1:η2:η1-(py)2C(CH2NO2)(O)−ligands doubly bridge the InIIIcenters and create a {In2(μ2-OR)2}4+core. Two pyridyl nitrogens of different organic ligands and two terminal halogeno ions complete a distorted-octahedral stereochemistry around each In(III) ion. After maximum excitation at 360 or 380 nm, the solid chloro complex 1emits blue light at 420 and 440 nm at room temperature, the emission being attributed to charge transfer within the coordinated organic ligand. Solid-state 115In NMR spectra, in combination with DFT calculations, of 1–3have been studied in detail at both 9.4 and 14.1 T magnetic fields. The nuclear quadrupolar and chemical shift parameters provide valuable findings concerning the electric field gradients and magnetic shielding at the nuclei of indium, respectively. The experimentally derived CQvalues are 40 ± 3 MHz for 1, 46 ± 5 MHz for 2, and 50 ± 10 and 64 ± 7 MHz for the two crystallographically independent InIIIsites for 3, while the δisovalues fall in the range 130 ± 30 to −290 ± 60 ppm. The calculated CQand asymmetry parameter (ηQ) values are fully consistent with the experimental values for 1and 2and are in fairly good agreement for 3. The results have been analyzed and discussed in terms of the known (1, 3) and proposed (2) structural features of the complexes, demonstrating that 115In NMR is an effective solid-state technique for the study of indium(III) complexes.

A thin uniform transparent film composed of the nonionic surfactant Triton X-100 and of poly(vinylmethylether), MW ≅ 30.000, has been deposited on a glass slide by dip-coating in a solution of reversed micelles in cyclohexane containing titanium(IV) tetraisopropoxide. Partial hydrolysis of the alkoxide assists in the attachment on the glass surface. Pyrene introduced in the film by original solubilization in cyclohexane forms diffusion-controlled excimers which can be switched on and off by changing the temperature. The pyrene-loaded film can be used as an optical oxygen sensor.