Sorption of selected organic compounds on organo-zeolites

• Autorzy: Szala B. , Turek P. , Bajda T. , Czerwiński J. , Franus W.
• Języki publikacji: EN

Abstrakty

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.

Słowa kluczowe

EN

natural zeolites; synthetic zeolites; aluminosilicate minerals

• Wydawca: Wydawnictwa AGH
• Czasopismo: Geology, Geophysics and Environment
• Rocznik: 2012
• Tom: Vol. 38, no. 4
• Strony: 539--540

Twórcy

autor

Szala B.

• AGH University of Science and Technology, Department of Geology, Geophysics and Environment Protection; al. Mickiewicza 30, 30-059 Krakow, Poland

autor

Turek P.

• AGH University of Science and Technology, Department of Geology, Geophysics and Environment Protection; al. Mickiewicza 30, 30-059 Krakow, Poland

autor

Bajda T.

• AGH University of Science and Technology, Department of Geology, Geophysics and Environment Protection; al. Mickiewicza 30, 30-059 Krakow, Poland

autor

Czerwiński J.

• Lublin University of Technology, Department of Civil Engineering and Architecture;Lublin, Poland

autor

Franus W.

• Lublin University of Technology, Department of Civil Engineering and Architecture;Lublin, Poland