Adsorption of fluoride on synthetic iron (III), zirconium(IV) and binary iron(III)-zirconium (IV) oxides: comparative assessment on pH effect and isotherm.

Fluoride is an accumulative poison at high dose of intake for humans and animals. In the present study, the sorption of fluoride from aqueous solution has been investigated on synthetic hydrous ferric oxide (HFO), hydrous zirconium oxide (HZO) and hydrous zirconium(IV)-iron(III) oxide (HZFO) by batch mode experiments. Both HFO and HZFO were crystalline and HZO was amorphous in nature. The parametes studied were the effect of pH and sorption equilibriums. The results showed increase in fluoride-sorption with increasing pH from nearly 2.0 to 5.0, 4.6 and 6.8 for HFO, HZO and HZFO, respectively. Analysis of temperature dependent sorption data obtained at equilibrium solution pH 6.8 (+/- 0.2) has been described by the Langmuir, Freundlich, Temkin and Redlich-Peterson isotherm model equations. The present sorption data fit, in general, found very well with the Langmuir and Redlich-Peterson models; and the data fit for HZFO and HFO found to increase, but for HZO the data found to decrease with increasing temperature. The computed thermodynamic parameters such as deltaG0, delltaH0 and deltaS0 from the Langmuir equilibrium constant (b, L/Umg) values show that the fluoride-sorption on HZFO was more spontaneous and endothermic process compared to HFO. The deltaH0 value obtained for fluoride adsorption on HZO indicates exothermic nature.

Ligand substitution reactions in trivalent lanthanum and aluminium acetylacetonates characterization of mixed ligand complexes

Neutral M[acac][3][M = La[III] or Al[Ill], Hacac = acetylacetone] reacts with pyridine-2,6-dicarboxylic acid [H2pdc], and gives [pdc]Al[acac] H[2]O and [pdc]La[acac]. 4H[2]O. Similar reaction with trichloroacetic acid yields [CCI3000]SI[acac]2. H[2]O, and [CCI3000xCH3C00]La[acac]. H[2]O, in which the ligand-substitution reaction is accompanied by decomposition of a coordinated acetylacetonate to acetate anion. Farther reaction of [CC13000]Al[acacn H2O with dichloroacetic acid produces the mixed chloroacetates [CCI3000XCHCI[2]COO]A1[acac]. 3H[2]O

Complexation of some antibiotics with lanthanum [III]

The interaction of La [III] with some selected antibiotics e.g. ampicillin, cephalexin, cephradine, oxytetracycline and tetracycline were studied by potentiometric or pH titrations. The stability constants of different binary complexes formed in such system have been determined at 25 +/- 0.1 and an ionic strength [M] of 0.1 mol. 1-1 by using the computer program Miniquad. The results showed the formation of 1: 1 complexes together with the corresponding hydrolyzed species. The solid complexes were separated and their composition and structure were confirmed by elemental analysis, IR spectrometry and conductometric measurements. The results showed that the beta-lactam antibiotics act as bidentate ligands, coordinated to the La [III] through the amino and the carbonyl-groups of side chain

Microanalysis of organolanthanum compounds

Simultaneous elemental microanalysis of organolanthanum compounds for C, H and La by the straight empty tube method of Korshun-Klimova is described. Additionally, complexometric, potentiometric, and spectrophotometric methods have been developed for the determination of the lanthanum content after oxygen flask combustion or wet digestion on micro, semimicro and submicro scales, respectively. The overall standard deviation for each of the 3 elements in the 5 compounds analyzed is 0.11%, whereas, the s value for La by the 3 methods is 0.11, 0.12 and 0.12%, respectively