A. Colella

Evaluation of an intermediate-silica sedimentary chabazite as exchanger for potentially radioactive cations

Intermediate-silica sedimentary chabazite contained in two chabazite-rich tuffaceous rocks has been evaluated as potential cation exchanger for radioactive cation removal from nuclear waste streams. Exchange isotherms have been obtained for the cationic couples Na/Ba, Na/Co, Na/Cs and Na/Sr and the relevant thermodynamic parameters calculated with the help of a computer program. Sedimentary chabazite turns out very selective for Cs þ , fairly selective for Ba 2þ and Sr 2þ , especially at low equivalent fraction of these cations in solution, and unselective for Co 2þ . An expla

Remediation of Cd- and Pb-polluted soil by treatment with organo-zeolite conditioner

The present work is part of a study focused on the use of organo-zeolite conditioner to remediate soil polluted by toxic elements. The Neapolitan yellow tuff (NYT) was utilized as a component of an organo-mineral sorbent/exchanger soil conditioner with pellet manure (NYT/PM) to reduce the mobility of Cd and Pb and recover plant performance in heavily polluted soils from illegal dumps near Santa Maria La Fossa (Lower Volturno river basin, Campania Region, southern Italy). Pot experiments were performed by adding the NYT/PM mixture (1:1, w/w) to polluted soil at the rates of 0%, 25%, 50% or 75% (w/w). Wheat (Triticum aestivum) was used as the test plant. The addition of organo-zeolite NYT/PM mixture significantly reduced the DTPA (diethylene-triamine-pentaaceti c acid)-extractable Cd and Pb from 1.01 and 97.5 mg kg−1 in the polluted soil, to 0.14 and 11.6 mg kg−1, respectively, in the soil amended with 75% NYT/PM. The best plant response was observed in amended soil systems treated with 25% NYT/PM, whereas larger additions induced plant toxicities due to increased soil salinity.

Neapolitan yellow tuff for the recovery of soils polluted by potential toxic elements in illegal dumps of Campania Region

The Neapolitan yellow tuff (NYT) was utilized as a component of an organo-mineral sorbent/exchanger soil conditioner with pellet manure (NYT/PM) to limit the mobility of Cd and Pb in heavily polluted soils from illegal dumps in Low Volturno river basin (Campania Region, southern Italy). The NYT/PM mixture (1:1, w/w) was added to soil at the rates of 0%, 25%, 50% or 75% (w/w). The overall significant effect of the amendment with NYT/PM on soil properties was the substantial reduction of the availability of the toxic elements, with special reference to Pb, connected with an increase of cation exchange capacity and electrical conductivity and a moderate decrease of soil pH. The observed effects were primarily ascribed to the Pb-selectivity of phillipsite and chabazite present in the tuff matrix. On the whole, our findings suggest the suitability of NYT as natural exchanger material to be utilized in strategies for the remediation of polluted sites.

Geological features, technological characterization and weathering phenomena of the Miocene Bryozoan and Lithothamnion limestones (central-southern Italy)

Bryozoan and Lithothamnion limestones (BLL) from centralsouthern Italy, commercially known as Perlato Royal Coreno, were used for a long time in the monumental architecture of the Campania and Lazio regions. In this paper, new mineralogical-petrographical and engineering geological data about BLL are reported and the relations between the lithofacial and technical features of this stone are investigated. A field survey of the main limestone outcrops allowed a lithostratigraphic reconstruction of this formation to be drawn and the eight main lithotypes presently used as dimension stones to be recognized. Mineralogical and petrographical characterization was performed by means of X-ray powder diffraction and optical microscopy observation of thin sections (under transmitted, UV-reflected light and cold cathodoluminescence). Petrophysical characterization enabled to compare some engineering-geological properties and to evaluate the influences of rock fabric, chemical composition, fractures and stylolithes on the technical features of the stone. Ageing tests were also performed. Finally the main weathering phenomena affecting the stone were recognised through a detailed study on the facades of the bell tower of the Santa Chiara monastery in Naples

Effectiveness of clinoptilolite in removing toxic cations from water: a comparative study

In order to evaluate the influence that structural and/or chemical inconsistencies exert over clinoptilolite behavior as an ion exchanger, a study has been performed aiming to compare the cation exchange properties of three different clinoptilolite-rich tuffs. Equilibrium data have been collected on two samples, coming from a Greek site and a Turkish site and having a similar framework chemistry. Exchange isotherms have been determined for some cation pairs of interest for practical applications and the related thermodynamic quantities calculated. The results, which have been compared with previously published data on a clinoptilolite sample from Sardinia (Italy), have shown analogous but not identical behaviors, possibly due to modest but not negligible differences in zeolite structure and/or original chemistry.

Modelling pedogenization of zeolitized tuff: effects of water and phenolic substances on weathering rates of the Campanian Ignimbrite (yellow facies)

Abstract An experimental pedology research project, based on a ‘‘process-system’’ pedogenetic model, was initiated to investigate the weathering of Phlegraean Yellow Tuff (PYT) - the yellow facies of the Campanian Ignimbrite with phillipsite > chabazite -as representative of the parent rock material as the soil-forming factor. PYT was weathered by water (W) and tannic acid solutions (TA) at concentrations ranging from 3×101 to 3×104 μmol l-1. The most concentrated TA solution (3×104 μmol l-1) showed the greatest extracting efficiency. Na and K were continually solubilized by W; Al, Ca and Mg contributed to the ionic composition of all the TA supernatants. A significant dissolution of the amorphous component and an associated decrease of the zeolite content, especially phillipsite, were noted. The features of PYT weathered outcomes fitted the ‘‘processsystem’’ model very well. PYT showed a pedogenic potential, in being prone to weathering, as well as in releasing elements of importance for plant settlement and development, such as K, Ca, Mg and Fe.

Zeolitized tuffs as pedogenic substrate for soil re-building. Early evolution of zeolite/organic matter proto-horizons

An investigation was undertaken aiming to evaluate the suitability of zeolitized tuffs as an anthropogeomorphic material for soil re-building in degraded and desertified areas. Four artificial soil proto-horizons were prepared utilizing fine limestone gravel or Neapolitan yellow tuff as inorganic components, and sewage sludge or pellet manure as organic parent materials. The proto-horizons evolution was followed by analyzing leachates periodically collected over 80 days. After 80 days, the body of proto-horizons was also analyzed. Our results showed that the release of C- and N- compounds in the leachates was strictly dependent on the nature of the parent organic material. The presence of Neapolitan yellow tuff in the proto-horizon bodies clearly favored an advantageous evolution and stabilization of parent organic matrices, in optimizing the carbon to nitrogen ratios by increasing the C/N values, and by protecting the organic matter tuff is a promising material in pedotechnique strategies for soil reconstruction and fight against desertification; on contrary, the organic matter appeared to be excessively demolished in the presence of limestone gravel.

Modeling pedogenization of zeolitized tuffs. II: medium-term weathering of phlegraean yellow tuff and red tuff with black scoriae by water and humic acids

An experimental pedology research program was started aiming at modeling the potential pedogenization of zeolitized tuffs. The present study deals with a medium-term weathering of Phlegraean Yellow Tuff (PYT, with phillipsite>chabazite) and Red Tuff with Black Scoriae (RTBS, with chabazite>phillipsite) under discontinuous treatment by water (W) and by humic acids (HA). Significant amounts of cations, increasing in the sequence Al<Fe<Mg<Ca, were extracted by both water and humic acids. The humic acids showed in all cases the highest extracting efficiency. All cations, especially calcium, were more easily removed from PYT than from RTBS. The only exception was iron which was preferentially removed from RTBS by HA. At the end of the experiment, smectite was not any more detected in the PYT residues. On the whole, the results indicate that PYT is more prone than RTBS to both humic acid and water weathering due to its different mineralogy.

Properties of zeolitized tuff/organic matter aggregates relevant for their use in pedotechnique. III: organic matter stability and exchange properties

Abstract A study was performed to evaluate the suitability of zeolitized tuffs to restore degraded soils. Ca-saturated Neapolitan yellow tuff or clinoptilolite-rich tuff from Turkey were mixed with organic matter either as humic matter (tannic acid, humic acids) or non-humic matter (polygalacturonic acid). Organic matter was strongly stabilized in clinoptilolite-rich tuff aggregates based on humic matter, whereas it was more easily oxidized in models with non-humic matter. Cation exchange capacity (CEC) was determined according to Ba/Mg-TEA method and by ammonium acetate procedure. The former method underestimated the CEC of the zeolitized tuffs, but was able to detect the contribution of organic matter to the CEC of aggregates. The latter method provided consistent CEC values for the zeolitized tuffs, but underestimated the exchange activity of the organic components of aggregates. CEC of aggregates including tannic acid was practically nil. Binding tannic acid to zeolite via Ca-bridges, results evidently in occlusion of zeolite pores.

01-O-05 - Ion-exchange features of intermediate-silica sedimentary phillipsite

Publisher Summary This chapter discusses the ion-exchange features of intermediate-silica sedimentary phillipsite. Equilibrium ion-exchange data for intermediate-silica sodium (Na)-exchanged phillipsite at 25°C, in the presence of cation pairs Na/X, where X is barium (Ba), cobalt (Co), potassium (K), or calcium (Ca), are collected, and the relevant thermodynamic parameters are computed. Phillipsite is found very selective for Ba, K, and ammonium (NH 4 ), unselective for Co, whereas only about 50% Na could be readily replaced by Ca. This behavior is interpreted in terms of phillipsites structural features.