Three different types of Fe(II)-modified natural zeolites were tested as supports in continuous-flow columns for the treatment of Cr(VI) contaminated water. The natural zeolites chosen as support were commercially available Zeosand (80% clinoptilolite), ATZ (79% phillipsite/chabazite), and ZS-55RW (90% Chabazite). All the examined modified zeolites turned out active for hexavalent chromium abatement, lowering its concentration below the European regulation level, even at relatively high flow rates (40 mL/h, linear velocity 15 cm/h). Zeosand, having a broader pH range of stability, was found to be the best one in terms of both Fe(II) uptake (0.54 wt%) and Cr removal (90 mg Cr/Kg zeolite).
The reduction of mercury emissions in currently existing coal-based power plant solutions by each method i.e. preliminary, primary and secondary (consisting of introducing coal into the combustion chamber and then removing mercury from the combustion gases arising from the combustion process) does not solve the problem of achieving the required limits by power plants. Therefore, the need has arisen to look for new, effective solutions.
The results presented in the work concern the analysis of environmental benefits for the use of zeolites obtained from by-products of coal combustion such as fly ash (from hard coal and lignite) in technologies for removing gaseous forms of mercury. The tested zeolites were silver-modified X-type structures. The reference material in the considerations was active carbon impregnated with bromine – a commercially available sorbent on the market.
The article considers environmental benefits resulting from the use of tested zeolites taking the product life cycle, sorbent efficiency and the possibility of its regeneration compared to activated carbon (AC/Br) into account. The LCA analysis was performed taking the estimated material and energy balances of the manufacturing processes into account. When comparing the production process of type X zeolite materials on the processing line and activated carbons in the amount necessary to capture 375 g Hg from exhaust gases, the LCA analysis showed that zeolites contribute to a lower potential impact on the environment. The advantage is that 5 times less zeolite sorbent than activated carbons is needed to capture the same amount of mercury. In addition, zeolite materials can be regenerated, which extends their life time
The objective of this study was to evaluate the effects of dietary zeolite clinoptilolite on re- productive performance, serum progesterone and insulin-like growth factor 1 (IGF-1) concentra- tions in 78 Holstein Friesian (HF) cows during pregnancy and lactation. The cows were divided into two groups comprising 40 (control group; CON) and 38 (CPL group) cows. To assess repro- ductive performance of HF cows the following variables were registered: the interval from calv- ing to first insemination (days open to first service, DFS), the interval from calving to pregnancy (days open to pregnancy, DOP), and the number of services per pregnancy (NSP). The average values of progesterone (5.64±0.59 ng/mL vs. 5.16±0.64 ng/mL) were not statistically different (p<0.05) and IGF-1 levels (400.17±17.72 ng/mL vs. 348.36±20.39 ng/mL) were higher in the CON than in the CPL group which received 50 g of clinoptilolite twice a day. However, in the CPL group ovarian cyclity resumed on days 40 and 60 postpartum. In addition, DFS (p<0.05) and DOP (p>0.05) were shorter in the CPL than in the CON group (115.1±19.9 and 137.5±36.3 days vs. 124.2±17.3 and 143.8±33.5 days, respectively). During 305 days of lactation, milk production was higher in the CPL vs. CON (8325.5±628.8 kg vs. 8050±586.8 kg). The NSP was lower in the CPL than in CON group (1.91 vs. 2.14). The dietary clinoptilolite supplement had a positive in- fluence on milk yield, exhibited modulating effects on endocrine status of dairy cows, and im- proved reproductive performance, with the decreased NSP, and fewer DFS and DOP.
The paper presents the results of hydrothermal zeolitization of fly ash from hard coal combustion in one of the Polish power plants. The synthesis was carried out using various NaOH fly ash mass ratio (3.0, 4.0 and 6.0) and the effect of NaOH concentration in the activating solution on composition of synthesized sample was tested. The process was carried out under the following permanent conditions temperature: 90°C, time – 16 hours, water solution of NaOH (L)/fly ash (g) ratio – 0.025. In the studied fly ash the dominant chemical components were SiO2 and Al2O3, while the main phase components were mullite, quartz and hematite, and a significant share of amorphous substance (glass and unburnt organic substance). After hydrothermal synthesis, the presence of unreacted fly ash phases was found in the products, as well as new phases, the quality and quantity of which depend on the NaOH to fly ash mass ratio used for synthesis:
for ratio 3.0 – Na-LSX type zeolite and hielscherite,
for ratio 4.0 – Na-LSX type zeolite, hielscherite and hydrosodalite,
for ratio 6.0 – hydrosodalite and hielscherite.
The grains in all products of synthesis are poly-mineral. However, it was found that the new phases, overgrowing the unreacted phase components of fly ash, crystallize in a certain order. Hielscherite is the first crystallizing phase, on which the Na-LSX type zeolite crystallizes then, and the whole is covered by hydrosodalite. In the products of synthesis, the share of sodium-containing phases (the Na-LSX type zeolite and hydrosodalite) increases with the increasing concentration of NaOH in the solution used for the process.
The issue of mercury emission and the need to take action in this direction was noticed in 2013 via the Minamata Convention. Therefore, more and more often, work and new law regulations are commencing to reduce this chemical compound from the environment. The paper presents the problem of removing mercury from waste gases due to new BREF/BAT restrictions, in which the problem of the need to look for new, more efficient solutions to remove this pollution was also indicated. Attention is paid to the problem of the occurrence of mercury in the exhaust gases in the elemental form and the need to carry out laboratory tests. A prototype installation for the sorption of elemental mercury in a pure gas stream on solid sorbents is presented. The installation was built as part of the LIDER project, financed by the National Center for Research and Development in a project entitled: “The Application of Waste Materials From the Energy Sector to Capture Mercury Gaseous Forms from Flue Gas”. The installation is used for tests in laboratory conditions in which the carrier gas of elemental mercury is argon. The first tests on the zeolite sorbent were made on the described apparatus. The tested material was synthetic zeolite X obtained as a result of a two-stage reaction of synthesis of fly ash type C with sodium hydroxide. Due to an increase, the chemical affinity of the tested material in relation to mercury, the obtained zeolite material was activated with silver ions (Ag+) by an ion exchange using silver nitrate (AgNO3). The first test was specified for a period of time of about 240 minutes. During this time, the breakthrough of the tested zeolite material was not recorded, and therefore it can be concluded that the tested material may be promising in the development of new solutions for capturing mercury in the energy sector. The results presented in this paper may be of interest to the energy sector due to the solution of several environmental aspects. The first of them is mercury sorption tests for the development of new exhaust gases treatment technologies. On the other hand, the second aspect raises the possibility of presenting a new direction for the management and utilization of combustion by-products such as fly ash.
The insecticidal efficiency of Ag-loaded 4A-zeolite (ZAg) and its formulations with Rosmarinus officinalis essential oil (RO) was evaluated against Sitophilus oryzae (L.) and Rhyzopertha dominica (F.). For comparison, different rates of ZAg (0.25, 0.5, 0.75, and 1 g ⋅ kg–1 wheat) were used solely and in a combination with LC50 concentrations of RO. Mortality was assessed after 7, 14, and 21 days of insect exposure to treated wheat. The progeny production was also evaluated. The use of ZAg accomplished a complete mortality (100%) on S. oryzae and 96.67% on R. dominica as well as 100% mortality of progeny against the two insect species after the longest exposing duration (21 days), at the highest rate (1 g ⋅ kg–1). On the other hand, the complete mortalities of ZAg formulations on S. oryzae were obtained after 14 d of treatment with F1 formulation (0.605 g ⋅ kg–1 RO + 0.25 g ⋅ kg–1 ZAg) and after 7 days with the other tested formulations. In addition, the complete mortality on R. dominica was obtained only by F8 (0.059 g ⋅ kg–1 RO + 1 g ⋅ kg–1 ZAg) formulation after 14 days of treatment. Concerning the efficiency of the examined formulations on the progeny of S. oryzae, F1 (0.605 g ⋅ kg–1 RO + 0.25 g ⋅ kg–1 ZAg) and F2 (0.605 g ⋅ kg–1 RO + 0.5 g ⋅ kg–1 ZAg) formulations recorded 100% mortality. In addition, F3 (0.605 g ⋅ kg–1 RO + 0.75 g ⋅ kg–1 ZAg) and F4 (0.605 g ⋅ kg–1 RO + 1 g ⋅ kg–1 ZAg) formulations suppressed the progeny production. Furthermore, the complete mortality of R. dominica progeny was obtained with F7 (0.059 g ⋅ kg–1 RO + 0.75 g ⋅ kg–1 ZAg) and F8 (0.059 g ⋅ kg–1 RO + 1 g ⋅ kg–1 ZAg) formulations. ZAg, especially its formulations with R. officinalis oil, had potential effects against two stored-product insects. F1 and F8 formulations could be treated efficiently on S. oryzae and R. dominica, respectively.
Greenhouse gases such as carbon dioxide and water vapour can be captured from gas streams on a zeolite 13X adsorbent. Experimental water vapour adsorption isotherms and kinetic curves were measured in the temperature range of 293–393 K and pressure up to 2100 Pa. The equilibrium data were developed with Toth and Sips multi-temperature isotherm models. The results of the process rate studies were described using pseudo-first and pseudo-second order kinetic models. Findings were compared with our own results of CO2 adsorption studies on the same zeolite.
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