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The application of natural coagulants derived from food byproducts in domestic wastewater tertiary treatment, which contains a number of impurities as suspended colloidal particles, has a potential use as essential substitutes for traditional inorganic coagulants. These biomaterials are a sustainable and environmentally friendly alternative that can be used to improve water quality and human health. In this study, prickly pear (PP) fruit peel mucilage gel was evaluated as a novel coagulant for the tertiary stage of domestic wastewater treatment. Jar tests were performed on residual raw water at the inlet (influent) and outlet (effluent) of the tertiary wastewater treatment (constructed wetland) with a coagulant dose of 12 mg L−1 at a pH of 13. The efficiency of green (i.e., mucilage) and inorganic chemical (i.e., FeCl3) coagulants was compared on the basis of turbidity and color removal. The flocs produced by the coagulants were characterized structurally by FTIR spectroscopy and Zeta potential analysis and morphologically by scanning electron microscopy (SEM). The results showed that the turbidity and the color removal efficiency of the mucilage compared to the FeCl3 at the outlet of the treatment (effluent) were practically the same, reaching 94% turbidity and 85–87% color removal efficiency with both coagulants. The structure and morphology of the flocs generated by the coagulants showed a higher content of organic matter trapped in the flocs. The floc formation observed mechanisms were adsorption/bridging for mucilage and charge neutralization for FeCl3. The results of this study demonstrated that the PP mucilage green coagulant can be used to enhance the quality of treatment of domestic wastewater in an eco-friendly and biodegradable manner. [ABSTRACT FROM AUTHOR]

Abstract: OCSe isolated in solid Ar or N2 at 10K was investigated by FTIR spectroscopy. The IR spectra of OCSe diluted in a 1:1000 proportion with the matrix gases were interpreted in terms of monomeric carbonyl selenide in a single matrix site. The IR spectra of more concentrated matrices revealed several new IR absorptions, which were tentatively assigned to different dimeric structures, aided by the prediction of quantum chemical calculations. The different matrices were exposed to UV–visible broad-band radiation, finding that monomeric OCSe decomposes into CO and Se, as evidenced by the IR absorption of CO perturbed by the presence of a selenium atom in the same matrix cage, while dimeric forms of OCSe decompose giving mainly (CO)2. [Copyright &y& Elsevier]

Two hitherto unknown difluoromethylselanes, HCF2SeH and ClCF2SeH, were formed by photolysis of difluoroselenoacetic and chlorodifluoroselenoacetic acids isolated in solid argon. The progress of the photolysis was monitored by FTIR spectroscopy. The photoproducts were identified by comparison of experimental with theoretically predicted spectra and reported spectra for known species. The photochemical decomposition mechanisms of HCF2C(O)SeH and ClCF2C(O)SeH is presented. [ABSTRACT FROM AUTHOR]

Abstract: The photochemical reactions between OCSe and Cl2 or Br2 isolated in solid argon at cryogenic temperatures were studied by means of FTIR spectroscopy. The OCSe⋯Cl2, OCSe⋯Br2 and SeCO⋯Br2 molecular complexes were identified by the shifts of the OCSe IR absorptions on complexation, and also by the IR activation of the Cl–Cl vibration in the first adduct. The hitherto unknown ClC(O)SeCl and BrC(O)SeBr molecules were formed upon UV–Vis irradiation of the matrix. The former was firstly obtained in the anti form, and subsequently photochemically transformed into the thermodynamically more stable syn conformation, while only the syn rotamer of BrC(O)SeBr was produced. The characterization of the novel species through their IR spectra was supported by the comparison with results of quantum chemical calculations. [Copyright &y& Elsevier]