Bio-zeolite use for metal removal from copper-containing synthetic effluents.

The adsorption capacity of biologically modified zeolite with respect to copper-containing effluents (Cu(II)-Fe(III), Cu(II)-Fe(III)-Ni(II), Cu(II)-Fe(II)-Zn(II), and Cu(II)-Fe(II)-Ni(II)-Zn(II)) has been investigated in order to apply it for industrial effluents treatment. Obtained bio-zeolite was characterized using neutron activation analysis, confocal laser scanning microscopy, and scanning electron microscopy. The efficiency of metal ions removal was determined as a function of pH, copper concentration, time, and temperature. The metal sorption in analyzed systems showed to be pH-dependent. The equilibrium adsorption data were interpreted using Freundlich and Langmuir isotherms and the adsorption mechanism was investigated by kinetic studies. The sorption of Cu(II) and Zn(II) fitted well pseudo-first and pseudo-second-order models, while Ni(II) sorption was better described by the Elovich model. The thermodynamic parameters, ∆G°, ∆H°, and ∆S were evaluated to understand the nature of the sorption process. Obtained results show that bio-zeolite is of interest for heavy metal ions removal from industrial effluents. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40201-021-00694-x.

Structure and gene cluster of the O-polysaccharide from Pseudomonas veronii A-6-5 and its uranium bonding.

A denitrifying bacterium Pseudomonas veronii A-6-5 was isolated from a deep aquifer contaminated with nitrates and uranium. The O-polysaccharide (OPS) was isolated by mild acid degradation of the lipopolysaccharide of P. veronii A-6-5 and studied using sugar analysis and 1D and 2D 1H and 13C NMR spectroscopy. The trisaccharide O-repeating unit was found to have the following structure: [Formula: see text] [Formula: see text] where Hb is 3-hydroxybutanoyl. The genome of P. veronii A-6-5 was sequenced and a respective OPS gene cluster was identified. Functions of the proteins encoded in the gene cluster, including the enzymes involved in the O-polysaccharide biosynthesis and glycosyl transferases, were putatively assigned by comparison with available database sequences. Formation of a new coordination bond between uranyl and the O-polysaccharide from P. veronii A-6-5 was demonstrated using FTIR spectroscopy; it may affect uranyl migration in the groundwaters due to its immobilization on microbial biofilms. Applied importance of this work is that the structure of the O-polysaccharide of a strain isolated from uranium-contaminated groundwater was determined and the character of interaction between the polysaccharide and the uranyl ion was established. The data obtained are of importance for development of the biotechnologies for treatment of uranium-contaminated groundwater and activated sludge.