Iron substituted ETS-10 samples with different Fe/Ti ratios were synthesised hydrothermally. The occurrence of a doublet with the isomer shift of octahedral Fe(III) in the Mossbauer spectra.

The effect of humic acid addition on the capacity of inorganic sorbents to sorb radioactive cesium and strontium was studied on montmorillonites in a calcium and potassium form. The Sips isotherm for humic acid sorption and multisite distribution model of ion sorption was found to suit well for the description of mobility of ions as a function of equilibrium humic acid concentration as a single variable at given pH and type of silicate. Complexation of the ions was of minor importance at the conditions investigated. Influence of humic acid on the specific radiocesium interception potential (SRIP) was also evaluated

الوصف

A standard analytical technique for determination of the partial ion exchange capacity of mineral or soil for selective uptake of cesium, the specific radiocesium interception potential (SRIP) is formulated and theoretically discussed. The method is based on the determination of a retained, leached or sorbed fraction of carrier-free cesium-137 in soil contacted with 0.01M KNO ₃ -0.01M Ag thiourea complex solution at the phase ratio solution:sorbent 10 ml:0.1 g. Reliability of the method is discussed in connection of radiocesium carrier and humic substances presence.

In general, the amount of radiocesium sorbed by the five sorbents with 0.01 mol·dm⁻³ NaCl was in order zeolite > NiFeCN−SiO₂ > montmorillonite > aerogel > silica gel. Addition of humic acid solution to the sorbents depressed the sorption of cesium by all sorbents, except for NiFeCN−SiO₂ was not seen, with the greatest effect showing to the aerogel. The presence of humic acid resulted in an enhanced desorption of cesium from zeolite, NiFeCN−SiO₂ and to a lesser extent from montmorillonite and silica gel. The order of cesium retention following desorption for both sorbent and sorbent/humic-acid mixtures was zeolit > NiFeCN−SiO₂ > montmorillonite > silica gel. The presence of humic acid resulted in decreasing of distribution coefficient values for both sorption and desorption processes.

Lead compounds still have numerous applications in our society, in spite of their known toxicity *. For example they are used in batteries and petroleum additives, paints and housing materials, catalysts and ceramics, glasses and semi-conductors. Elemental analysis will readily show the presence of lead but precise knowledge of the form it takes should be accessible with solid-state 2G7pb NMR, because NMR can probe the local environment of the lead atom(s) 2 ' 8 . The enormous chemical shift range, >15,000 ppm, already established for lead 9 suggests that small changes in its environment will lead to easily detected changes in chemical shift provided that the usual line narrowing techniques developed for solids, such as magic angle spinning (MAS), are successful. On the other hand, distortions from regular geometry around the lead atom will induce large changes in chemical shift anisotropy, and make detection more difficult as has been found for ^H g *0. The aim of this work has been to investigate parameters and variables required for the successful detection of this nucleus which has very favourable properties ( spin 1/2, 21% natural abundance) in the solid state. We have recently shown that 207pj, NM R spectra of solid lead(II) nitrate are significantly and uniformily dependent on temperature ?. Here we present results for some simple lead compounds as well as for model sytems related to soils such as leadexchanged zeolites H