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Single crystals of strontium tetracobalt tris(orthophosphate) hydroxide, SrCo4(OH)(PO4)3, were grown serendipitously under hydrothermal conditions at 473 K. The crystal structure consists of undulating chains of edge-sharing [CoO6] octahedra that are linked into (010) layers by common vertices between chains. Adjacent layers are linked along [010] into a framework structure by tetrahedral [CoO4] units and by PO4 tetrahedra. The framework delimits channels extending along [100] in which the eleven-coordinate strontium cations are situated. Bifurcated O—H...O hydrogen bonds of weak strengths consolidate the crystal packing. The title compound was also characterized by infrared spectroscopy.

Single crystals of dibarium cobalt(II) bis(orthoborate), Ba2Co(BO3)2, have been obtained from the melt. The crystal structure is composed of two isolated (BO3)3− triangles linked to Co2+ cations. The resulting [CoO5] square pyramids and the borate anions make up branched rows extending parallel to [010]. The barium cations occupy two sites in the voids of this arrangement and exhibit coordination numbers of nine each. A comparison with the structures of other A2M(BO3)2 compounds reveals a unique five-coordination of the small metal M in the title compound instead of four- or six-coordination for the other A2M(BO3)2 compounds with M = Cu, Zn, Mg, Ca, or Cd.

In this work, geopolymer synthesized with perlite and an alkaline activator medium was evaluated as a new adsorbent and photocatalyst for degradation of methylene blue (MB) dye from an aqueous medium. The functional group, the structure, and the morphology of the raw and the synthesized materials were characterized using FT-IR, XRD, and SEM analysis. The degradation of MB in the contaminated solution was examined using the spectrophotometric technique. Several analysis methods revealed the formation of the aluminosilicate gel after the geopolymerization reaction. The kinetics data with UV and without UV irradiations were well fitted with the pseudo-second-order equation. The results indicated that the degradation efficiency of cationic dye by perlite-based geopolymer without and with UV was up to 88.94% and 97.87% in 4 hours, respectively. The degradation efficiencies of methylene blue are in the following order: perlite-based geopolymer under UV irradiations is greater than perlite-based geopolymer without UV irradiations that is larger than UV irradiations. The overall experimental results suggested that the new elaborated material with synergetic adsorption and photocatalytic activities has a great potential for the treatment of water contaminated by hazardous substances.