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1
Content available remote Sorpcja jonów Cr(VI) na powierzchniowo modyfikowanych zeolitach naturalnych
PL
Dokonano przeglądu literatury na temat modyfikacji naturalnych zeolitów kationowymi surfaktantami organicznymi i ich zastosowań w procesie sorpcji jonów Cr(VI). Omówiono mechanizm sorpcji HDTMA na materiałach zeolitowych oraz metody analizy modyfikowanych powierzchni. Dyskusję efektywności modyfikacji oparto na analizie termicznej (DTA, TG) oraz widm FTIR i FT Ramana. Omówiono mechanizm sorpcji jonów Cr(VI) na modyfikowanych zeolitach oraz metody analizy (XRD, spektrofotometria MID). Porównano efektywności sorpcji jonów chromu(VI) na modyfikowanych naturalnych zeolitach.
EN
A review, with 69 refs., of methods for modifying zeolites with cationic surfactants and methods used for anal. of modified materials. An impact of the modifications on sorption efficiency was also presented.
EN
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).
3
Content available remote Adsorpcja zanieczyszczeń gazowych na minerałach zeolitowych
PL
Zeolity naturalne są to szeroko rozpowszechnione w przyrodzie glinokrzemiany, których unikatowe właściwości sorpcyjne można wykorzystać do ograniczenia emisji gazów odlotowych. Efektywność procesu zależy od rozmiaru i polarności cząsteczek gazu, składu mineralogicznego i chemicznego, budowy strukturalnej minerału oraz siły i rodzaju uformowanych wiązań. Zastosowanie odpowiedniej modyfikacji powierzchni zeolitów (aktywacji termicznej lub chemicznej) daje możliwość zmiany powinowactwa sorbentu i zwiększenia jego pojemności sorpcyjnej.
EN
A review, with 47 refs., of thermal and chem. methods for activation of natural zeolites use as sorbents in air pollutants. Dealumination of zeolites by leaching with strong acids was also taken into consideration. Data on the sorption efficiency of the activated adsorbents in sepn. of H₂S, CO₂, PrH, AcOBa, Me₂CO, MeH, EtH and ethylene were included.
EN
The characterization and porous structure of raw and modified clinoptilolite as a sorbent has been investigated by nitrogen adsorption, X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, differential thermal analysis, scanning electron microscopy and atomic force microscopy methods. The nitrogen adsorption data revealed that the total pore volume and specific surface area were increased after modification. The nitrogen adsorption was used to determine percent of mesoporosity. The TG data show that 14 wt. % of clinoptilolite is lost after heating up to 1200 °C. Two types of porosities - primary porosity (microporosity) and secondary one (meso- and macroporosity) have been observed.
5
Content available remote Sorption of selected organic compounds on organo-zeolites
EN
Zeolites are microporous, aluminosilicate minerals that are characterized by cage-like structures, high surface areas, and high cation-exchange capacities. They are widely used as commercial adsorbents: in industry for water purification; as catalysts, for the preparation of advanced materials and in nuclear reprocessing. Zeolites are used to extract nitrogen from the air in order to increase oxygen content for both industrial and medical purposes and they are also used in agriculture. Natural zeolites form where volcanic rocks and ash layers react with alkaline groundwater. Currently, the world's annual production of natural zeolite is about 3 million tonnes. Demand for zeolites is extremely high, with their usage continually on the increase. Unfortunately, natural zeolites contain an admixture which reduces the purity of their composition. Furthermore, natural zeolites' properties (CEC, charge, size of cavities etc.) make it difficult to implement them in specific chemical processes - further perpetuating the demand for synthetic zeolites. Sorption of apolar substances on zeolites is low because the process takes place only on the outer surface of the crystallites. To increase the chemical affinity of the zeolite's surface to the apolar organic compounds, organic ions from quaternary ammonium salts such as hexadecyltrimethylammonium bromide (HDTMA) and dodecyltrimethylammonium chloride (DDTMA), replaced the natural cations on their exchangeable positions. HDTMA and DDTMA have a strong affinity for the zeolite's surface and replace positively charged inorganic counter-ions and neutralize the negative surface charge of the zeolite. The aim of the study was to determine the effectiveness of sorption for organically modified zeolites produced from fly ash for benzene, toluene, ethylbenzene, xylene, phenol, aniline, naphthalene, gasoline, phenan-threne, anthracene and pyrene. Material used in this study was an X-type zeolite prepared from coal fly ash. As a result of alkaline reaction of fly ash with NaOH, experimental cases bring zeolitic materials that are rich in a Na-X phase. The synthesis was performed by pouring 400 mL of an aqueous solution of NaOH onto 20 g of fly ash. This process was carried out for 24 hours at 75°C. After a series of reactions, the material was washed twice with distilled water to remove the excess NaOH solution. The result of this process was to ultimately obtain a product containing 60% zeolite . HDTMA and DDTMA were adsorbed on a synthetic zeolite in amounts of 1.0 and 2.0 of the external cation exchange capacity (ECEC) in quantities of 24.4 mmol and 48.8 mmol per 100 g of zeolite respectively. In order to select the optimal conditions for modification, the test was performed with different ratios of the solid product (zeolite) to the solution (aqueous solution of ammonium salts). Ratios used were: 1:10, 1:20, 1:30, 1:40, with modification temperature: room temperature, 40°C, 60°C and 80°C. On Surfactant-Modified Zeolite (SMZ) sorption of apolar compounds was performed. 200 mg of the organo-zeolite was placed in a tube and 10 cm aqueous of benzene, toluene, ethylben-zene, xylene, phenol, aniline, naphthalene, gasoline, phenanthrene, anthracene and pyrene was added. After modification with the HDTMA and DDTMA surfactans, the zeolite used in this work shows a significant ability to remove organic contamination from aqueous solution. As a result of this, the maximum sorption capacity of organo-zeolites and zeolites in terms of these compounds was ultimately determined. Synthetic zeolites exhibit very good sorption properties and HDTMA proved to be a better surface modifier than DDTMA. Sorption efficiencies of apolar compounds were observed at greater than 80% for all compounds in solutions. The results of this research can be used in environmental protection as well as for further study on the properties of SMZ and their potential industrial applications.
EN
Removal of phenol (Phen) andp-nitrophenol (p-NPhen) from aqueous solutions onto sodium modified (ZG-Na) and surface modified (ZG-HDTMA) natural zeolite has been investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) technique characterizations show that clinoptilolite is the major phase in zeolitic rock. Batch system was considered to determine the kinetics and isotherm type of the adsorption of NOJ by the ZG-Na and ZG-HDTMA. Results suggest a better fit to the adsorption data than the pseudo-first order kinetic model. It seems that the Langmuir model best describes the experimental data. p-NPhen is selectively adsorbed by both ZG-HDTMA and ZG-Na.
PL
W dobie wzrastającego zanieczyszczenia środowiska naturalnego istotne jest poszu-kiwanie coraz efektywniejszych metod ich usuwania. W szczególności zastosowanie tanich i łatwo dostępnych katalizatorów "proekologicznych" - naturalnych zeolitów, pozwala na intensyfikację wielu procesów, a ponadto nie są wnoszone do środowiska dodatkowe zanieczyszczenia. Szerokie zastosowanie naturalnych zeolitów - uwodnionych glinokrzemianów, wynika z ich wyjątkowej struktury przestrzennej, nadającej im właściwości molekularno-sitowe, jonowymienne i sorpcyjne oraz dużą aktywność katalityczną. Ich powierzchnię można łatwo modyfikować jonami metali. Stąd mogą one być z powodzeniem stosowane jako heterogeniczny katalizator w procesie Fentona, do utleniania zanieczyszczeń organicznych w wodzie i ściekach. W pracy opisano właściwości fizykochemiczne zeolitu naturalnego modyfikowanego jonami żelaza (II), który następnie poddano prażeniu w temperaturze 450°C. W wyniku modyfikacji ziarna zeolitu pokryte zostały czerwonobrunatnymi tlenkami żelaza (III), które stanowiły ok. 5% masy zeolitu. Powstała powłoka była stabilna mechanicznie i chemicznie - do roztworu przechodziły niewielkie ilości Fe, nie przekraczające 70 /
EN
Currently, when the pollution of natural environment increases, the search for more effective methods of pollutant removal is essential. Application of cheap and easy to get pro-ecological catalysts - natural zeolites - allows to intensify many processes. These minerals do not bring any additional pollutant to the environment. Wide application of natural zeolites, the hydrated alumino-silicates results from their unique spatial structure. Such structure of zeolites gives them molecular sieve properties, ionic exchange and sorption properties, and high catalytic activity. The surface of zeolites can be easily modified with metal ions, therefore they can be used as heterogeneous catalyst in the Fenton process. In this paper physicochemical properties of natural zeolites modified with Fe(II) ions, calcinated at 450°C are presented. As a result of modification, zeolite grains were covered by red-seal iron (III) oxides, which were about 5% of zeolite mass. Coating was mechanically and chemically stable -from zeolite to solution leached only small amounts of Fe, not exceeding 70 /
EN
The results of the experiments on water migration in unsaturated beds of natural zeolite (clinoptilolite) performed with a dynamic neutron radiography technique are presented. It was found that the migration of water in zeolites is much slower than in quartz sand composed of the same size grains. The effect is attributed to the enormous grain surface roughness of the zeolite. The influence of gravity was found to be significant only for beds formed by the coarsest grains. It was found that the water imbibition rate increases with time in finest grain zeolite beds. The results show the difficulties of the classical theory of adhesion driven motion of the liquid in the single capillary as a model of water imbibition by zeolite beds.
11
Content available remote Oczyszczanie ścieków zeolitami w SBR przy różnych układach faz procesowych
PL
Przedstawiono badania przeprowadzone w skali laboratoryjnej nad oczyszczaniem ścieków syntetycznych zeolitami naturalnymi w porcjowym reaktorze sekwencyjnym SBR. Przyjęte w badaniach różne układy faz procesowych (zmienne warunki atoksyczne, anaerobowe i aerobowe) umożliwiły dokonanie oceny skuteczności i zasadności dozowania do komory biologicznego oczyszczania naturalnych zeolitów. Badania prowadzono w dwóch reaktorach, z których pierwszy stanowił poziom kontrolny, w drugim - proces osadu czynnego wspomagano zeolitem, stanowiącym aktywny nośnik biofilmu. Stężenie zeolitu w SBR nie przekraczało 1 g/l. Uzyskane wyniki badań wykazały znaczny wzrost efektywności oczyszczania ścieków w obecności zeolitu. Stanowił on dobre podłoże dla rozwoju mikroorganizmów, stabilizował prace osadu czynnego oraz poprawiał jego właściwości sedymentacyjne. Nie stwierdzono negatywnego oddziaływania zeolitu na bakterie osadu czynnego. Pomimo wprowadzanych zmian układu faz procesowych 8-godzinnego cyklu reaktora SBR w obecności zeolitu obserwowano każdorazowo wzrost intensywności nitryfikacji i denitryfikacji oraz defosfatacji w stosunku do reaktora kontrolnego.
EN
This paper describes lab-scale experiments of wastewater treatment in sequencing batch reactor at the different process phases using zeolites. These natural minerals, due to their skeleton structure have such properties as: sorption, ion exchange and molecular-sieve, used in sewage treatment technologies too. Researches were conducted in two reactors, working at the range of decantation coefficient 0.5. The first one was a control reactor and sewage was treated only in the process of activated sludge. The second reactor was operated with the zeolite added, which was a carrier of biofilm. At the end of aeration phase excess sludge was removed to maintain total sludge age of 10 d. Synthetic wastewater used in the experiment consisted of organie (peptone and bouillon) and minerał (NH4CI, NaCl, CaCl, MgSO4, KH2PO4, K2HPO4) compounds. Once a day dusted zeolite, with graining less than 250 μm were dosed reaching fixed concentration on level of 1 g/L. Reactors were operated with a cycle time of 8-hours. Each cycle consisted of phases: filling, mixing in anoxic - anaerobic condition, aerating, settling and decantation of purified wastewater. During the tests the time-sequenced anoxic/toxic phases were changed. A comparison of gained treatment results allowed to estimate the effectiveness and legitimacy of the zeolites dosage to the biological treatment chamber. These results showed that wastewater treatment with added natural minera even at different phases of SBR operation was more effective. Zeolites had a positive influence on activity of activated sludge, sludge settleability (adding zeolites influenced on decreasing the sludge volume index SVI) and increased concentrations of biomass (growth at interface and in pores of mineral). The higher reduction of COD, BOD5, TP and TKN was observed in a purified sewage from reactor with added zeolite. These minerals increased the efficiency of organic and phosphorus removal, nitrogen transformation and removal from the wastewater. Zeolite made convenient breeding ground for microorganisms. Removing phosphorus compounds from the wastewater in presence of zeolite was the result of higher biological stimulation of microorganisms while removing of nitrogen compounds was a result of both physico-chemical and biological process.
12
Content available remote Catalytic oxidation of volatile organic compounds containing chlorine
EN
The catalytic oxidation of selected chlorinated hydrocarbons was investigated in the presence of natural zeolites modified with 3M HC1 and chromium and lanthanum from aqueous solutions. Modified zeolite catalysts were resistant to processes of dealumination and were active in processes of the catalytic oxidation of chlorinated hydrocarbons. The presence of steam contributes to reducing the quantity of chlorine formed as well as chloroorganic and carbocenous deposits.
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