Fly Ash Derived Zeolites in the Removal of Toxic Compounds

The present paper describes the previous obtained results concerning purification of gases, water and sewages from toxic components such as mercury, radionuclides and petroleum substances. The tested materials constitute synthetic zeolites obtained in hydrothermal reaction, i.e., Na-X, Na-P1, and natural zeolite clinoptilolite. The zeolites (Na-X, Na-P1 and clinoptilolite) needed for mercury capture were activated by silver ions; however, for the removal of petroleum substances (Na-X and Na-P1) as well as radionuclides (Na-P1) raw zeolite materials were used. The review of the results have shown that zeolites used both for mercury capture and the removal of radionuclides, as well as petroleum substances, can be considered promising sorbent materials

The mineralogy, geochemistry and health risk assessment of deposited particulate matter (PM) in Kraków, Poland

One of the most important air contaminants in Krakow is particulate matter (PM), especially during winter months. Deposited PM was sampled between November 2014 and January 2015 and November 2015 and January 2016. The PM deposition amounted to 0.0646 g/m2 per day in the centre of Krakow and 0.0328 g/m2 in the northern district of the city. The allowed value of annual dust deposits (0.547 g/m2 per day) was not exceeded. The XRD and SEM-EDS analysis showed that quartz, calcite, potassium feldspar, plagioclase, kaolinite, and gypsum were the main mineralogical components of the deposited PM. Only in a few samples were illite, dolomite, and apatite observed. Significant concentrations were measured (ICP-MS) for Ca, Fe, Mg, Al, K, Si, Na, and Mn, and high concentrations for Ti, Cu, Zn, As, Pb, Cr, Ti, V, Li, Sr and Ni. The highest estimated daily intakes (EDI) for resuspended PM, were stated for ingestion exposure pathway than for dermal contact, and finally for inhalation, both for children and adults, as well as, for carcinogenic and non-carcinogenic elements. The mean hazard quotient (HQ) values for all three exposure pathways decreased in the following order: Fe > Al > Zn > Mn > Sr > Cu > Ba > Cr > Pb > V > Ni > Li > As > Sn > Zr > Co > Cd > Be, for children and adults. The hazard index values for all elements in each exposure pathway (HIelem) and for single elements in all exposure pathways (HIpath) were <1, both for children and adults. The risk values from all three exposure pathways were unacceptable in the case of Cr, both for children and adults, and in the case of As for children. The total non-carcinogenic risk (HItotal) values in all three exposure pathways for all elements were <1, however in case of children the risk value pointed to a low risk level. The total carcinogenic risk (Rtotal) values in all three exposure pathways for As and Cr exceeded the acceptable level, both for children and adults

Na-P1 zeolite synthesis and its crystalline structure ripening through hydrothermal process using coal combustion by-products as substrates

Energy industry sector is one of the major environment pollutants. This branch also generates significant amounts of by-products such as slugs, slug-ash mixtures, ashes and microspheres, which can be very harmful for the earth ecosystems. Statistically the microspheres (MIC) constitute from 0.6% to 2.5% of the total amount of post combustion wastes. MIC occurs mainly in fly ashes (less often in slugs) as the smallest, hollow, spherical particles. MIC is composed mainly of crystalline and amorphous aluminosilicate phases. The combustion conditions have strong influence on MIC composition. Mineral and chemical composition of MIC is very similar to F type of fly ashes; consequently there is a possibility to use them as substrates for zeolite synthesis. Zeolites are minerals from microporous, aluminosilicate group (Szala et al. 2015). Among others, they are characterized by specific channels and chambers occurrence in their structure, which results in a number of important features like: ion exchange, sorption, molecular sieve or catalytic properties. This is the reason for wide use of zeolites in numerous industrial sectors (Ahmaruzzaman 2010). The aim of this study is a synthesis of Na-P1 zeolite at semi-technical scale by conversion of microspheres under hydrothermal conditions in an alkaline medium. This study involves also research of Na-P1 zeolite structure ripening in order to optimize the synthesis conditions. Microspheres from Stalowa Wola Power Plant (Poland) were used as a substrate. For the synthesis of Na-P1 phase the following conditions were applied: 90 dm 3 of water, 15 kg of microsphere, 11 kg of sodium hydroxide (3 mol/dm 3 ), temperature: 80°C, and reaction time up to 26 h (Franus et al. 2014). The zeolite conversion was performed on semi-technical scale installation (Wdowin et al. 2014). During the conversion, samples were collected from the reactor after 2, 4, 6, 10, 14, 26 hours. To investigate the influence of time for zeolitization process efficiency these samples were analyzed in terms of chemical and mineral composition, structural and textural properties. The main attention was paid to the evolution of the Na-P1 unit cell parameters observed as a function of time (calculations and models were performed for every sample). The phase’s composition was determined with powder X-ray diffraction (XRD) method using a PANalytical X’pert MPD diffractometer (with a PW 3050/60 goniometer), Cu lamp, and a graphite monochromator. The analysis was performed within the angle range of 5–65 2θ. PANalytical X’Pert Highscore software was used to process the diffraction data. The identification of mineral phases was based on the PDF-2 release 2010 database formalized by the ICD and IZA-SC Database of Zeolite Structures. The experimental calculations of the unit cell parameters were performed using UnitCell software. The spatial model of Na-P1 zeolite cell was prepared using Mercury 3.7 Windows software. The morphological forms and the chemical composition of the main mineral components were determined with scanning electron microscope (SEM) FEI Quanta 250 FEG equipped with the SE detector and a system of chemical composition analysis based on energy dispersive X-ray-EDS of EDAX company. N 2 adsorption-desorption measurements were carried out at 77 K using ASAP 2020 volumetric adsorption analyzer (Micromeritics). The specific surface areas (S BET ) of the samples were evaluated using the standard Brunauer–Emmett–Teller (BET) method for nitrogen adsorption data in the range of relative pressure p / p 0 from 0.06 to 0.3. The total pore volumes were estimated from single-point adsorption at a relative pressure of 0.98. XRD data indicates that main phases in microsphere are amorphous aluminosilicate glass, mullite and quartz. The obtained product is dominated by Na-P1 phase. Experimental calculations of cell parameters and fabricated models confirm crystallographic similarity to Na-P1 pattern. Noteworthy is the fact that the unit cell parameters depend on reaction time. Calculations indicate that the cell parameters (walls length: a , b , c and cell volume) increase with time towards to pattern values. This phenomenon may be interpreted as a ripening of crystalline structure. An in-depth look at this matter can lead to better estimation of synthesis conditions, which have a significant impact to the total cost of zeolites production – especially at a larger scale. SEM shows progressive dissolution (also as a function of time) of aluminosilicate glass in favor of crystallization of zeolite phase. EDS analysis confirms similarity of chemical composition of the obtained samples to a standard Na-P1 zeolite. Calculated textural properties indicate increase of S BET with the reaction time. Simultaneously, the average pore diameters decrease. The S BET of synthetized Na-P1 was 4.62 m 2 /g after 2 h but it increased to 47.92 m 2 /g after 26 h. This is an effect of growing contribution of zeolite phase in relation to the initial substrates in the sample during the reaction time. The experimental conditions allowed synthesizing Na-P1 zeolite from microsphere particles in the prototype installation. Zeolitization process strongly influences the textural properties by increasing S BET and improving pore structure. The microsphere from Stalowa Wola Power Plant is a promising material for the synthesis of Na-P1 zeolite in the prototype installation. Still, the reaction parameters should be reconsidered, basing on the obtained results, in order to reduce the cost of the zeolite production as much as possible. This is required before proceeding to the full technical production scale. To observe increase of zeolite amount in entirety synthesis batch (and to link it with cell behavior) the Rietveld analysis will be provided

CO2-brine-rock interactions as a result of long term experiment onto rock samples from Chabowo anticline, Poland

The presented work concerns investigations of CO2 -brine-rock interactions conducted over a period of 20-months. Experiments were carried out at laboratory scale with the use of equipment specifically designed for this purpose. Research materials (reservoir and cap rocks) were taken from the Chabowo 3 well located within Chabowo anticline. The experiments were carried out at room temperature (about 25ºC) and pressure about 6 MPa. For samples before and after the experiment a numerous investigations were carried out i.e. petrophysical (porosity, surface area, threshold diameter, average capillary, framework and bulk densities) and petrological-mineralogical characteristics. Also brine used for examination before and after experiment was analyzed (chemical analysis). Petrophysical results have shown a significant decrease of porosity (from 17.0% to 7.5%) and surface area (from 0.395 m2 /g to 0.196 m2 /g) in case of sandstone. These changes are caused probably by crystallization of halite in pore spaces, because mineralogical analysis (XRD) has shown the presence of halite (3–5% vol. in the rock) after experiment. More detailed results were obtained during mineralogical analyses of thin sections. These results have shown in sandstone samples a small increase of porosity and a small decrease of feldspar and cements (carbonate and clay) as well as matrix which suggests dissolution of these constituents. For claystone – after experiment XRD clay fraction has shown absence of clay minerals such as montmorillonite, which may also be caused by interaction between the rock, CO2 and brine. Dissolution of some minerals is evidenced by chemical analysis of brine where amounts of most tested ions increase after experiment for both sandstone and claystone

An analysis of the chemistry, mineralogy and texture of waste dolomite powder used to identify its potential application in industry

In this work the characteristic of the dolomite powder was carried out due to specifying possible industrial applications. After technological use of dolomite aggregates remaining fine powder becomes waste. Raw and calcined powder samples were subjected to mineralogical, textural and chemical studies involving leaching tests. The results of the calcination process indicate that the carbonate minerals present in the material sample undergo complete decomposition in the form of oxides. After the calcination, the material is practically non-porous and its surface area is more than five times smaller than that of the raw material. However, due to the high content of calcia in the calcined sample (CaO >45% wt.), the material cannot be used as an additive in cement. Leaching tests showed that the concentration of metals that can leach from the dolomite powder is not high enough to classify the material as hazardous waste according to the TCLP test. Moreover, the concentration of metals that can get into the environment does not exceed permissible values according to the Polish law. Thus it is recommended and justified to carry out detailed tests in view of the environmental protection i.e. wet flue gas desulfurization, heavy metals absorption, CO2 capture

Experimental study of mercury removal from exhaust gases

An initial study has been made of the use of synthetic zeolites for mercury capture from exhaust gases. Synthetic zeolites (Na-X and Na-P1), and for comparison a natural zeolite (clinoptilolite) and activated carbon with bromine (AC/Br) were tested for mercury uptake from a gaseous stream. The materials were subjected to mercury adsorption tests and their thermal stability was evaluated. The untreated synthetic zeolites had negligible mercury uptake, but after impregnation with silver, the adsorption of mercury was markedly improved. The synthetic zeolite Na-X impregnated with silver adsorbed significantly more mercury before breakthrough than the activated carbon impregnated with bromine, indicating the potential of zeolite derived from coal fly ash as a new sorbent for capture of mercury from flue gases