Joanna Konczyk

Calixarene-based extractants for heavy metal ions removal from aqueous solutions

ABSTRACT The article reviews the literature on the possibility of application of the calixarene-based compounds for selective separation of toxic heavy metals from aqueous solutions by the solvent extraction and transport across liquid membranes. The specific three-dimensional structure of calixarenes and their derivatives, simple and low-cost synthesis, and ease of chemical transformation qualify these compounds for the role of selective chemical extractants of toxic heavy metal ions present in industrial wastewater. This article analyses the influence of various process factors, with the greatest emphasis on the structure of the extractants/carriers, on efficient separation of heavy metal ions, primarily those most commonly found in galvanic wastewater.

Er5Ni3Al3Ge4 : a quaternary variant of the NbCoB type

Single crystals of pentaerbium trinickel trialuminium tetragermanium were synthesized from the elements by arc-melting. The novel compound crystallizes in the space group Pmmn, e6b2a, with all nine crystallographically unique atoms in special positions of site symmetries m.. and mm2. This compound represents a new ordered variant of the NbCoB type. Its two-layer structure is described as an intergrowth of the Er3NiAl3Ge2 (Y3NiAl3Ge2 type) and ErNiGe (TiNiSi type) structures. The coordination polyhedra are distorted pentagonal prisms around Er atoms, tetragonal prisms around Al and Ni atoms, and trigonal prisms around Ge and Ni atoms, capped with eight, four and three extra vertices, respectively.

Erbium dicobalt disilicide, ErCo2Si2

Single crystals of erbium dicobalt disilicide were synthesized from the corresponding elements by arc melting. The ternary intermetallic compound crystallizes in the body-centred tetragonal space group I4/mmm and adopts the CeGa2Al2 structure type, with all atoms in special positions.