A polymeric oxovanadium(IV) pyromellitate complex

The reaction of oxovanadium(IV) sulphate with 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid) in the presence of potassium carbonate yields a polymeric complex, K2[VO(pyr)]·6H2O (I) [pyr = pyromellitate(4-) ion]. The PM3(tm) calculations and IR spectroscopy suggest that the polymeric structure of I consists of -V-pyr-V-pyr- chains formed by the 1,4- or 1,5-bridging by the pyr ions. The chains are additionally cross-linked by the chelate function of one of the COO- groups of the pyr ion. Magnetic measurements do not reveal the presence of antiferromagnetic coupling between the V centers

A study of the removal of copper ions from aqueous solution using Clinoptilolite from Serbia

Toxic metal contamination of waste waters can be mitigated by metal adsorption to clay and zeolitic minerals, but in developing countries such environmental remediation can be cost prohibitive if these minerals are not readily available. Because of its abundance, low cost, and excellent selectivity for several toxic metal ions, clinoptilolite from the Zlatokop deposit in Serbia was investigated for its ability to remove copper ions from aqueous solutions and serve as an effective local resource for this purpose. The sorption capacity of the clinoptilolite at 298 K varied from 8.3 mg Cu g (for C = 100 mg Cu dm ) to 16.8 mg Cu g (for C = 400 mg Cu dm ). The sorption data were best described by the Freundlich isotherm and the sorption kinetics followed the pseudo-second-order model. Intra-particle diffusion of Cu was present but it is not the rate-limiting step. The sorption of Cu on the clinoptilolite occurred spontaneously, the free energy change decreasing with temperature. The sorption was endothermic and was accompanied by an increase in entropy. Dehydration of the Cu-loaded clinoptilolite at 540°C led to the formation of nanocrystalline Cu(I) oxide particles with an average size of ~2 nm, suggesting possible novel applications for the Cu-loaded clinoptilolite

Hydrothermal synthesis and structure of a new layered zincophosphate intercalated with 3-Methylaminopropylamine cations

A novel layered zincophosphate (ZnPO–MPA) was prepared by hydrothermal crystallization using 3-methylaminopropylamine (MPA) as a structure-directing agent. The structure consists of macroanion [Zn2P3O8(OH)3]2- layers which are built up of 4-membered ring channels. The channels (of about 3.7 Å diameter) arise through the connection of the neighbouring rings by two oxygen bridges. The negative charge of the layers is compensated by diprotonated MPA molecules which are stacked parallel to the ring channels. ZnPO–MPA is stable up to 300 °C. At higher temperatures MPA decomposition begins followed by a dehydration, which occurs through condensation of the framework hydroxyl groups. The activation energy of the MPA decomposition is high due to the fact that the layers and MPA cations are held together by strong hydrogen bonds

On the thermal degradation of 3-methylaminopropylamine captured inside the aluminum phosphate analog of ULM-3

An open-framework aluminophosphate analog of the fluorogallophosphate structure-type ULM-3 was obtained by hydrothermal crystallization of an aqueous aluminum phosphate suspension in the presence of 3-methylpropylamine (MAPA) and hydrofluoric acid. The open-framework fluorinated aluminophosphate structure was confirmed by Rietveld analysis and the (27)Al, (31)P, and (19)F MAS NMR spectroscopy. The MAPA, located in the ten-membered ring channels, is doubly protonated to balance the negative charge of the Al(3)P(3)O(12)F(2) (2-) framework. Thermogravimetric analysis data have been used to study kinetics of the thermal decomposition of MAPA. The decomposition was found to be a complex process, its activation energy varied from 177 to 259 kJ mol(-1). The relatively high E values are explained by the fact that the MAPA cations are bound to the anionic framework both by electrostatic forces as well as strong N-HaEuro broken vertical bar O hydrogen bonds. The strength of the interactions is indirectly confirmed by the in situ high temperature X-ray diffraction analysis which shows that the MAPA decomposition leads to a phase transformation of the open-framework structure to the dense trydimite phase

Kinetic, equilibrium and thermodynamic studies of nickel adsorption in batch on a red alga corallina elongata

Nickel is a heavy metal used in many industries such as electroplating, battery manufacture, forging, finishing and metal extraction, which contributes to environmental pollution (Salini et al. in Sep Sci Technol 51:1317–1327, 2016)