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In recent years, composite semiconductor photocatalytic materials have received significant attention as a novel type of materials and technical means. So in this work, CdS-modified TiO2 nanowires are fabricated on natural zeolite by simple sol-gel and hydrothermal synthesis method. This novel composite semiconductor photocatalytic material has almost solved the shortcomings of pure TiO2, such as easy cohesion, low utilization rate, and exceedingly weak photocatalytic activities under visible light. The degradation efficiency of methylene blue dye in water is near to 90% with CdS-modified TiO2 nanowires/zeolite composite materials after 60 min under visible light, which indicated its huge potential application in wastewater treatment.

The increase in concrete structures’ durability is a milestone to improve the sustainability of buildings and infrastructures. In order to ensure a prolonged service life, it is necessary to detect the deterioration of materials by means of monitoring systems aimed at evaluating not only the penetration of aggressive substances into concrete but also the corrosion of carbon-steel reinforcement. Therefore, proper data collection makes it possible to plan suitable restoration works which can be carried out with traditional or innovative techniques and materials. This work focuses on building heritage and it highlights the most recent findings for the conservation and restoration of reinforced concrete structures and masonry buildings.

A FAU-X-rich porous monolith has been obtained by means of an unconventional two-stage method consisting of the production of a foamed geopolymeric precursor and its subsequent conversion by means of a hydrothermal method. The influence of the conversion process parameters, such as NaOH concentration (0.1–2 M), treatment temperature (40–80 °C) and time (24–72 h) on the FAU-X crystallization was studied. Collected data revealed that the highest yield in terms of zeolite content and FAU-X/LTA ratio was obtained performing the hydrothermal treatment with a 0.5 M NaOH solution at 60 °C. The crystallization kinetics of FAU-X inside the geopolymer precursor was investigated by means of Synchrotron Radiation X-Ray Diffraction Quantitative Phase Analysis (SR-XRD-QPA). Results showed that the crystallization starts after an induction time of about 3 days, and the weight percentage of the zeolite in the sample raises up to about 78% after 20 days of treatment. The highest yield in terms of zeolite content, about 80% of FAU-X and 6% of LTA, was reached at 20 days. Finally, Scanning Electron Microscopy (SEM) analysis showed the presence of well-defined octahedral crystals either on the pore surface or in the bulk of the sample starting from 3 days of hydrothermal treatment.

The topic of sustainability of reinforced concrete structures is strictly related with their durability in aggressive environments. In particular, at equal environmental impact, the higher the durability of construction materials, the higher the sustainability. The present review deals with the possible strategies aimed at producing sustainable and durable reinforced concrete structures in different environments. It focuses on the design methodologies as well as the use of unconventional corrosion-resistant reinforcements, alternative binders to Portland cement, and innovative or traditional solutions for reinforced concrete protection and prevention against rebars corrosion such as corrosion inhibitors, coatings, self-healing techniques, and waterproofing aggregates. Analysis of the scientific literature highlights that there is no preferential way for the production of “green” concrete but that the sustainability of the building materials can only be achieved by implementing simultaneous multiple strategies aimed at reducing environmental impact and improving both durability and performances.

Natural zeolites are used as adsorbents in purification processes due to their cation-exchange ability and molecular sieve properties. Surface modified natural zeolites (SMNZs), produced by attaching cationic organic surfactants to the external surface, can simultaneously act as ionic exchangers and organic molecule adsorbents. In this paper, SMNZs were produced and investigated as adsorbents for As(V) removal from wastewater: two natural zeolites, clinoptilolite and phillipsite, were modified using HDTMA-Br and HDTMA-Cl as surfactants. The obtained samples were then characterized under static and dynamic conditions. Results showed that As(V) removal follows a pseudo-second order kinetic, with fast adsorption rates: every sample reached 100 % removal in 2 h, while equilibrium data showed a Langmuir-like behavior, with a greater anion uptake by the HDTMA-Br modified SMNZs due to the formation of a compact and complete micellar structure. Finally, fixed-bed tests were performed to characterize the samples under dynamic conditions assessing the effect of severe operating parameters on the dynamic exchange capacity, selectivity and efficiency of the process. The obtained results demonstrate a good ability of the tested materials to adsorb As(V) from wastewater, confirming the effectiveness of the proposed surface modification technique in expanding the possibility of using natural zeolites in these processes.

A great challenge of research is the utilization of natural or synthetic zeolites, in place of natural pozzolans, for manufacturing blended cements. The difficulties of interpretation of the pozzolanic behavior of natural zeolite-rich materials and the role played by their nature and composition can be overcome by studying more simple systems, such as pure synthetic zeolites. This study aims at investigating the pozzolanic ability of isostructural zeolites with different framework compositions, such as three sodium zeolites of the faujasite (FAU) framework type: LSX, X, and Y. The pozzolanic activity has been estimated by thermogravimetry and X-ray diffraction analysis. The overall outcome of the investigation is that the zeolite structure affects its pozzolanic activity, as zeolites with similar framework densities exhibit distinct abilities to fix lime. Moreover, the framework composition is effective either from a kinetic point of view or on the total amount of fixed lime. Zeolite X appears to possess the best average features.

In this work, the potentialities of the amino-functionalized, chromium-based MIL-101 metal organic framework (NH2-MIL-101) as a high capacity, fully regenerable hydrogen chloride adsorbent have been proved by a thorough adsorption thermodynamics investigation. The chosen adsorbent showed high gaseous HCl adsorption capacities and, to the best of our knowledge, it is the first example of a totally regenerable substrate for this kind of adsorbate, as evidenced by both experimental and modeling results. This paves the way to the implementation of greener, more energetically efficient pressure/temperature swing adsorption processes to purify biogas feeds for high-temperature fuel cells.

An adsorbent based on polyethylene oxide-templated silica monoliths with hierarchical uniform porosity was functionalized with polyethylenimine and was used as a substrate for CO 2 adsorption. Such material, denoted PEI-MonoSil, was characterized by means of thermogravimetric analysis and N 2 adsorption/desorption at 77 K, in order to prove that polymer chains efficiently filled the pores of functionalized samples. CO 2 adsorption isotherms on PEI-MonoSil were evaluated at T = 298, 313, 333, and 348 K for pressures up to 100 kPa by means of a volumetric technique. CO 2 adsorption data revealed a meaningful dependence of the CO 2 adsorption capacity on temperature, with the highest capacity registered at 348 K. CO 2 adsorption on PEI-MonoSil was convincingly modeled by means of the Toth isotherm. The comparison between the results obtained in the present work and those relative to CO 2 adsorption on other nanoporous substrates allowed to highlight a notable affinity of PEI-MonoSil towards CO 2 and a high level of heterogeneity in the adsorbent/adsorbate interaction. Eventually, the modeling effort also allowed to evaluate the isosteric heat of CO 2 adsorption as a function of the fractional coverage of PEI-MonoSil, showing values that are comparable with experimentally estimated values of the enthalpy of reaction between CO 2 and monoethanolamine solutions.

The ion-exchange properties of a synthetic hydrosodalite (Na-hS) have been investigated by kinetic and thermodynamic analysis of exchange reactions of the original sodium form for lithium, potassium and calcium forms. Kinetic curves, modelled by a Langmuir-type equation, revealed that exchange rate for lithium and for potassium are of the same order, whereas they are two order faster than for calcium. Thermodynamic analysis of the cation exchange isotherms pointed out that sodalite is selective for sodium over the other three cationic forms examined, which is consistent with the preference exhibited by the sodalite type for sodium environments, either in natural or in laboratory crystallization. Na/Li and Na/Ca exchanges are incomplete, whereas unexpectedly Na/K exchange turns out to be complete, even though K+ dimension exceeds the width of the access window to sodalite cages. The obtained results have been discussed in terms of Eisenman–Sherry theory, pointing out agreements and discrepancies.

In this work, hydrogen sulfide (H2S) adsorption on a laboratory-synthesized polymeric chromium terephthalate (MIL-101) metal-organic framework was modeled by means of the semiempirical Sips equation in order to obtain parameters of engineering interest. MIL-101 (Cr) samples, synthesized by a simple solvothermal process, were characterized by means of X-ray diffraction, field-emission scanning electron microscopy, microporosimetric analysis and Fourier transform infrared spectroscopy. High crystallinity, very high specific surface area and pore volume were found. H2S adsorption isotherms on MIL-101 (Cr) were evaluated at four different temperatures (273, 298, 323 and 348 K) at pressures of up to approximately 0.1 kPa by means of a gravimetric technique using a McBain-type balance. The modeling and experimental results showed that MIL-101 (Cr) had a high H2S adsorption capacity at near-ambient temperature and low heat release during adsorption, suggesting a potential use of the selected metal-organic framework for fixed-bed adsorption operations.

Amino-functionalized mesoporous silicas (AFMS) were synthesized by a neutralization route using the anionic surfactant dodecanoic acid (DAA) as structure-directing agent (SDA), aminopropyltrimethoxysilane (APTMS) as co-structure-directing agent (CSDA), and tetraethoxysilane (TEOS) as silicon source. The synthesis parameters, which affect the structural properties and the amino loadings of the resultant AFMS, were optimized. Various techniques, such as FT-IR, XRD, N2 adsorption-desorption, and TEM, were used to characterize the synthesized AFMS. The selective removal of Cu2+, Pb2+, Cd2+, and Zn2+ from aqueous solutions in single-, binary-, ternary-, and quaternary-component systems by the synthesized AFMS was thoroughly investigated. The measured single-component adsorption isotherms of Cu2+, Pb2+, Cd2+, and Zn2+ on the AFMS optimally synthesized can be well described by the Sips model, in which the extracted adsorption capacities are 2.34, 2.86, 1.71, and 1.36 mmol/g (0.149, 0.593, 0.192, and 0.089 g/g) for Cu2+, Pb2+, Cd2+, and Zn2+, respectively, higher than those on other adsorbents reported in the literature. Furthermore, Pb2+ and Cu2+ can be more selectively removed by the synthesized adsorbent, compared to Cd2+ and Zn2+, confirmed by the results on the multi-component adsorption.

The galeb of Kebili is a sun-dried brick belonging to the construction tradition of the homonymous “oasis city” of southern Tunisia, obtained by mixing water, fired gypsum-rich Sahara sand and palm wood ash. In recent years, great efforts have been made to enhance the features of these construction materials while preserving the traditional production techniques. In order to evaluate possible improvements in the brick’s physical and mechanical properties, both different firing techniques of raw materials and various ash content in the composition, have been considered. Experimental results showed that modifying the traditional method of combustion by firing the sand at a controlled temperature (160 °C) in a standard oven, allows to obtain a galeb brick with improved mechanical and physical properties. Moreover, keeping the traditional method of combustion, mechanical and physical properties may be optimized by adding a controlled amount of raw ash (about 5 %) in the galeb bricks composition.

To better understand the water vapor adsorption behavior of metal organic frameworks, a microporous copper triazolate was synthesized and used as a substrate to evaluate water vapor adsorption isotherms at four different temperatures (293, 303, 323 and 343 K). Samples of [ Cu 3 II (triazolate)3(OH)3(H2O)4]·4.5H2O were obtained as powders by partially modifying a procedure reported in the literature and characterized by means of X-ray diffraction, scanning electron microscopy, particle size distribution, thermogravimetry and microporosimetric analysis. The experimental data for the water vapor adsorption were submitted to non-linear regression using the semiempirical Sips equation, which led to a good correlation between model curves and experimental points. Moreover, the dependence of the isosteric heat on the fractional coverage of the adsorbent was successfully calculated by the van’t Hoff equation and Sips theoretical isotherms.

In a previous paper the authors demonstrated that adding glass fibers to hydraulic lime-based mortars leads to clear improvement in the post-cracking behavior. In order to enhance physical and mechanical performances of the above fiber reinforced mortars, the use of zeolitic addition was proposed. A phillipsite-rich tuff and a zeolite A [LTA] were selected and added in the mixtures. A significant decrease in open porosity and increase in mechanical behavior was achieved with each addition. In particular 20% of LTA produces an improvement of flexural and compressive strength up to 150% compared with fiber reinforced mortars without addition.

Organic-inorganic hybrid foams based on an alkali alumino-silicate matrix were prepared using different foaming methods. Firstly, silico-aluminate inorganic matrix, activated through a sodium silicate solution, was prepared at room temperature. The obtained viscous paste was expanded by means of silicon metal redox reaction in alkaline media in combination with protein-assisted foaming. The foamed systems were hardened at defined temperature and time and then characterized by FTIR, scanning electron microscopy, and compression tests. The high temperature behavior and specific surface area were also evaluated. The experimental findings highlighted that the combination of silicon metal and vegetable protein allowed tailoring hybrid foams with enhanced properties: good yield strength and thermal resistance typical of geopolymeric foam with a ductile behavior (toughness) and low density typical of organic foams.

The feasibility of some widespread zeolite-rich tuffs to act as pozzolanic material for manufacturing blended cements was evaluated by chemical and mechanical characterization. Two different methods were used: (a) Fratini’s test, that allowed to evaluate the ability of the pozzolanic material to combine with Ca(OH) 2 in a blended cement; (b) Saturated Lime Test, where the pozzolanic behaviour was directly evaluated in a lime saturated solution. Mechanical characterization was carried out by measuring compressive strength of blend mortars, after 28-day curing. The good pozzolanic behaviour proved by all the tuffs, coupled with their low cost, makes very promising the use of zeolitic tuffs for the production of eco-sustainable blended cements.

In the present work, the synthesis of mesoporous material sieves in pure silica form (MCM-41 and MCM-48) and Al, Fe, Cu and Zn containing, having different pore diameters (corresponding to those between the upper limit for zeolites and the lower end of the mesoporous materials), high pore volumes (>0.8 cm 3 /g) and high specific surface areas (>1000 m 2 /g) is presented. The advantages of these materials in the adsorption technologies depend on their high specific surface area and pore volume as well as on the possibility to vary their pore size distributions under mild synthesis conditions and without post-synthesis treatments. The different capacities of CO 2 sequestration of these mesoporous materials, with respect to the N 2 adsorption capacities, at room temperature and pressure of 1 bar, were studied. The results show that these materials have high CO 2 adsorption capacity and selectivity (≅42 cm 3 /g and CO 2 /N 2 ≅ 22, respectively), and high working capacity (≅17 cm 3 /g). These adsorption parameter values are comparable to those of the best adsorbents used in VSA processes.

The P/T phase stability and the thermo-elastic behavior of synthetic TlAlSiO 4 [ABW framework type, space group Pna 2 1 , a = 8.2719(2), b = 9.4373(2), c = 5.4180(1) A] have been investigated up to 950 °C (at room- P ) and up to 8 GPa (at room- T ) by means of in situ synchrotron powder diffraction with a diamond anvil cell and with a high-temperature furnace. The Rietveld structure refinement of TlAlSiO 4 at room P/T confirms the general structure model previously reported. Only one independent Tl site, with full site occupancy and close to channel wall, represents the extra-framework population. No phase transition has been observed within the temperature- and pressure-range investigated. P – V data were fitted to a second-order Birch–Murnaghan Equation of State (BM-EoS), giving: V 0 = 420.76(5) A 3 , K T0 = 48.8(2) GPa. The evolution of the lattice parameters with pressure shows a significantly anisotropic compressional pattern. The elastic parameters calculated with a “linearized” second-order BM-EoS are: K T0 ( a ) = 21.96(7) GPa for the a -axis; K T0 ( b ) = 68(1) GPa for the b -axis, and K T0 ( c ) = 112(2) GPa for the c -axis. The volume thermal expansion with T was modeled by the polynomial function: V ( T )/ V 0 = 1 + α 0 ·Δ T + α 1 ·Δ T 2 = 1 + 4.44(3)·10 −5 ·Δ T − 2.3(3)·10 −9 ·Δ T 2 . The anisotropic thermal scheme is characterized by a negative thermal expansion along [010] (i.e. α 0 ( b ) = −8.5(1)·10 − 6 °C −1 ), almost no expansion along [0 0 1] (i.e. α 0 ( c ) = 0.9(1)·10 − 6 °C −1 ) and a positive expansion along [1 0 0] (i.e. α 0 ( a ) = 52.4(1)·10 − 6 °C −1 ). A comparative analysis of the thermo-elastic behavior of the isotypic TlAlSiO 4 and CsAlSiO 4 is carried out.

A solidification–stabilization procedure aiming at immobilizing Cs+ and Sr2+, two of the radioactive species more frequently present in nuclear power plant wastewaters, was successfully tested. Both cations were simultaneously exchanged by a blend of two zeolites, a phillipsite-rich tuff, selective for Cs+, and a synthetic zeolite Linde-type A, selective for Sr2+. The contaminated material was then heat treated up to 1200 °C with the result of safely immobilizing both cations, as demonstrated by leaching estimation with three different procedures. X-ray studies of the single cation-loaded zeolites or mixture of them helped to interpret the immobilization mechanism, involving cation trapping in chemically stable crystalline/amorphous matrices formed as a result of firing.

The aim of the present work is the study of the migration from active LDPE polymer films of ?-tocopherol adsorbed onto purely siliceous and amino-functionalized SBA-15 mesoporous silica. In particular, the effect of the pore size and the chemical functionality of the internal walls of the mesophase was thoroughly investigated. Co-condensation of tetraethylorthosilicate and aminopropyltriethoxysilane was exploited to bind amino groups on the pore surface of SBA-15. The synthesized mesoporous powders were characterized by means of X-ray diffraction and N2 adsorption/desorption at 77 K. Powders loaded with tocopherol were characterized by infrared spectroscopy and thermogravimetric analysis. Results show that the maximum of the pore size distribution reduces from 90 Å for purely siliceous SBA-15 to 73 Å for amino-functionalized SBA-15. Infrared analysis shows that tocopherol interacts with the amino groups of functionalized SBA-15. Migration tests were performed at 25 °C, using 96% v/v ethanol as fatty food simulant, on both polymer films containing about 1% wt/wt of free tocopherol and about 3% wt/wt of tocopherol loaded onto purely siliceous and amino-functionalized SBA-15. The tocopherol diffusivity of films containing functionalized mesoporous silica decreased of about 60% with respect to films containing free tocopherol. This is due to the decrease in the pore size and to the increase in diffusion resistance caused by the functionalization of the internal pore walls with the amino groups. Moreover, the oxygen radical absorbing capacity assay of the produced active polymer films proved the antioxidant effectiveness of tocopherol released from samples after manufacturing process.

CdS and PbS nanoparticles sensitized ZnO nanorods were synthesized by successive ionic layer adsorption and reaction method. The photocatalytic activity of different structures was evaluated by photocatalytic degeneration yield of methyl orange. Co-sensitization of CdS and PbS nanoparticles on ZnO nanorods showed enhanced photocatalytic activity due to its response at visible light area and the stepwise band gap constructed in ZnO/CdS/PbS nanostructures.

To investigate the pozzolanic activity of zeolites, experimental blended cements prepared by mixing together ordinary Portland clinker, isochemical sodium zeolite s type A [LTA] or X [FAU], and gypsum, were subjected to the Fratini’s test, i.e., the official test recognized in the European Standards. The same mixtures without gypsum were used to prepare cement pastes with deionized water, which, after curing for 3–28 days, were subjected to mechanical strength measurements. Both zeolites proved to be effective as pozzolanic materials. Their action involved various steps, including (1) cation exchange, (2) dissolution and/or breakdown of the zeolitic structure, (3) possible formation of transient gel phases, and (4) precipitation of hydrated calcium silicates and aluminates. Pozzolanic activity was demonstrated to depend on zeolite structure. Zeolite A reacted, in fact, more readily than zeolite X. Zeolite X, on its turn, being slightly more siliceous than zeolite A, contributed to a greater extent to the development of the mechanical resistances of the cement pastes at short curing times.

After a historical survey, the present status of research on thermodynamic aspects of ion exchange in Italian natural zeolites, namely phillipsite, chabazite and clinoptilolite, is reported. Equilibrium data relative to exchange reactions between these zeolites and various toxic and noxious cations, namely Cd2+, Pb2+, Cu2+, Zn2+, Cs+, Sr2+, Ba2+, Co2+, NH 4 + , and two representatives of alkaline and alkaline-earth cations, such as K+ and Ca2+, are critically reviewed. Exchange isotherms and the most relevant thermodynamic quantities, such as the equilibrium constant Ka and the standard Gibbs free energy ΔG0, are reported. Furthermore, the exchange isotherms are interpreted in terms of selectivity of one cation over another, and the selectivity series are analyzed in the light of the Eisenman–Sherry theory and on the basis of the structural features of the various zeolitic terms. Eventually, a thermodynamic model recently proposed as a tool to predict either the ion exchange behaviour of a zeolite for varying compositions of the aqueous phase, or the equilibrium behaviour of multicomponent systems based on the experimental data relative to binary systems, is discussed.

Adsorption equilibria of water and ethanol vapors on a zeolitized tuff from Campania (Southern Italy), containing both phillipsite and chabazite, were studied. The adsorption isotherms of both compounds on a tuff sample with a grain size ranging from 120 to 60 mesh and having a total zeolite content of 40% were determined at temperatures of 20, 40, 60 and 80 °C and furthermore the same isotherms were determined at T = 20 °C and T = 80 °C on two other samples of the same tuff, having zeolite contents of 18% and 68% and grain size distributions in the ranges >120 mesh and 60 × 35 mesh, respectively. The experimental results were satisfactorily interpreted in terms of the pore filling Dubinin–Astakhov model. The model used allowed to estimate the micropore volume of the three grain size fractions considered (ranging from 36 to 121 ml/kg) and the characteristic energy of adsorbate–tuff interaction (about −20 kJ/mol for water and about −25 kJ/mol for ethanol). Furthermore, the binary (water–ethanol) adsorption isotherms were predicted. The overall results indicated that a strong correlation between zeolitic content of the tuff and adsorption capacity exists and that the selected tuff is very selective towards water, with a molar separation factor in the order of 6–7 if the azeotropic mixture is considered.

Cesium retention performances of two different natural zeolites (an Italian phillipsite-rich tuff and a Mexican erionite-rich tuff), pre-exchanged in Cs form and heat-treated, are compared. After thermal treatment at 1000 °C both zeolites satisfactorily retain Cs during back-exchange tests with NaCl solution or by a prolonged contact with distilled water. The different mechanisms of Cs encapsulation are elucidated. The Cs-exchanged phillipsite, a less siliceous and less heat-stable zeolite, tends to form pollucite on heating. Pollucite is a naturally occurring mineral phase which contains and irreversibly traps cesium. The Cs-exchanged erionite tends to form an amorphous phase on heating and Cs is immobilized through glass formation.

Preliminary data concerning the monitoring in situ of the zeolite A crystallisation from clear solutions are reported. Experiments were performed at 60 and 70°C with fresh and aged solutions having the following composition: 8.6Na 2 O·0.18SiO 2 ·Al 2 O 3 ·150H 2 O. The formation of early phases in the crystallisation process were followed using diagnostics such as dynamic light scattering (DLS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The comparison of the available data seems to indicate the formation of a precursor phase (like gel) in the case of not aged solution. Conversely, crystallisation in aged solution seems to proceed without intermediate phases. At the same time, an investigation on the kinetics aspects of the zeolite A crystallisation was carried out. As far as the reproducibility test is concerned, the chemical system selected showed good results on a large number of tests.

Different ion exchange selectivities for Cs of two phillipsites, one sedimentary and one synthetic, having similar framework compositions, were interpreted by means of Rietveld structural analysis. Both phillipsites were pre-exchanged to achieve Na forms throughout exhaustive elution using an NaCl solution and then enriched in Cs by contact with mixed Cs + and Na + solutions. X-ray diffraction data of the original and Cs-exchanged samples were refined using the Rietveld method. Four extra-framework sites labelled I, II, II′, and II″ were refined. Cation distribution in the four sites showed that, although sites I and II are readily occupied by Cs, some Na is prone to be retained in site II′, which displays therefore a reduced selectivity for Cs. The new site II″ is occupied by Cs. The synthetic sample retains much more Na than the sedimentary sample, and this is the reason for the higher selectivity of the sedimentary phillipsite for Cs compared with the synthetic one. The results of this work also suggest that phillipsite may be utilized as a selective cation exchanger for the removal of Cs + radionuclide in nuclear waste.

The ability of phillipsite to remove lead from water was evaluated by determining lead exchange isotherms with sodium- or potassium-exchanged phillipsite and by studying the kinetics of sodium exchange for lead and, lastly, by testing lead uptake in a column, in which fixed beds of sodium-enriched phillipsite tuff grains were percolated by lead-containing solutions. The collected data evidenced a remarkable selectivity of sodium phillipsite for lead in equilibrium experiments, fast kinetics, and massive lead removal from water in column runs, even in the presence of substantial amounts of sodium as interfering cation. The favourable lead elution during regeneration of exhausted phillipsite together with the above mentioned results in the exchange experiments allow to forecast a profitable utilization of phillipsite in lead removal from waste water.

Cs and Sr exchange reactions for Na on sedimentary, hydrothermal and synthetic phillipsites are studied by determining their exchange isotherms at 25 degrees C and 0.1 total normality, and computing the related thermodynamic quantities K-a, and Delta G degrees. Sedimentary and synthetic phillipsite, characterized by a higher Si/Al ratio, display good selectivity for Cs and moderate selectivity for Sr. The more aluminous hydrothermal phillipsite displays a lower selectivity for Cs and a higher selectivity for Sr than sedimentary and synthetic phillipsite do. These results, perfectly explainable in terms of field strength of the anionic zeolite framework and of ion charge density, demonstrate that the joint removal of Cs and Sr from water by phillipsite would be possible, provided cheap widespread aluminous phillipsite-rich materials were available.