Abstract:Zeolites and zeolite rocks are commonly used in different industrial applications. Natural zeolites present an attractive material for environmental applications because of their high abundance, availability and low costs. Depending on geological settings and conditions during mineral formation, natural zeolite deposits usually represent a heterogeneous mixture of zeolite minerals together with varying amounts of gangue minerals (e. g. quartz, feldspars and phyllosilicates). Hence, profound mineralogical knowl… Show more
“…Natural zeolites are hydrous framework aluminosilicates which are frequently used as sorbents for water and wastewater treatment [15]. Synthetic zeolites and their nanocrystalline precursor phases can also be used [16,17], but natural zeolites are often preferred in industrial applications due to their lower costs [18]. The crystal structure of clinoptilolite (Ca 0.5 ,Na,K) 6 [20].…”
Ammonium (NH4+) is a main constituent of landfill leachates (50–2200 mg L−1) which has to be removed prior to indirect (<200 mg L−1) or direct discharge (<10 mg L−1) during landfill operation and aftercare, i.e., for more than 100 years after the end of waste disposal. In this study, lab‐scale experiments regarding the sorption of NH4+ from landfill leachates using natural and modified clinoptilolite (Ca0.5,Na,K)6(Al6Si30)O72·20H2O) were conducted to assess the applicability of the innovative ion exchanger loop stripping (ILS) process for ammonium recovery. Samples of 20 g clinoptilolite after different pre-treatments (Ca loading, Na loading, natural loading) were shaken with 500 mL of each leachate from ten Austrian landfills (75 mg L−1 < c(NH4+) < 2805 mg L−1; 7.7 < pH < 8.7) for 24 h. Between 13% and 61% of the dissolved NH4+ was adsorbed to the clinoptilolite, which remained stable during the experiment. In summary, our study indicates that the ILS process is highly promising with respect to NH4+ recovery from landfill leachates, but further research is needed to reach threshold values for direct discharge.
“…Natural zeolites are hydrous framework aluminosilicates which are frequently used as sorbents for water and wastewater treatment [15]. Synthetic zeolites and their nanocrystalline precursor phases can also be used [16,17], but natural zeolites are often preferred in industrial applications due to their lower costs [18]. The crystal structure of clinoptilolite (Ca 0.5 ,Na,K) 6 [20].…”
Ammonium (NH4+) is a main constituent of landfill leachates (50–2200 mg L−1) which has to be removed prior to indirect (<200 mg L−1) or direct discharge (<10 mg L−1) during landfill operation and aftercare, i.e., for more than 100 years after the end of waste disposal. In this study, lab‐scale experiments regarding the sorption of NH4+ from landfill leachates using natural and modified clinoptilolite (Ca0.5,Na,K)6(Al6Si30)O72·20H2O) were conducted to assess the applicability of the innovative ion exchanger loop stripping (ILS) process for ammonium recovery. Samples of 20 g clinoptilolite after different pre-treatments (Ca loading, Na loading, natural loading) were shaken with 500 mL of each leachate from ten Austrian landfills (75 mg L−1 < c(NH4+) < 2805 mg L−1; 7.7 < pH < 8.7) for 24 h. Between 13% and 61% of the dissolved NH4+ was adsorbed to the clinoptilolite, which remained stable during the experiment. In summary, our study indicates that the ILS process is highly promising with respect to NH4+ recovery from landfill leachates, but further research is needed to reach threshold values for direct discharge.
“…Aydag Zeolite in the Tovuz district is one of the most significant deposits in the region. Natural zeolites extracted here are successfully used in agriculture as they enhance the soil quality, increase the productivity of most plants and are used as inert food supplements in the husbandry sector, aiming to absorb heavy metals and radioactive substances from animals' bodies, as well as cleansing harmful contaminants from industrial wastes, improving the gasoline quality, in oil production, as catalyst in oil and chemistry processes, in rubber, plastic and paper sector, in filtering systems at purifying stations and in health care [16].…”
Subject. The article describes natural resource capabilities of the Ganja-Gazakh Economic Region of Azerbaijan, with the diversity, quantity, quality, exploration degree and parameters of raw material source exploitation in the region being a cornerstone for this.
Objectives. The study is to promote such projects that involve an increase in both internal and external investment in the Ganja-Gazakh Economic Region. To achieve that, local authorities should improve the investment climate and prepare the acts – decisions within their areas of expertise that promote investments in the modernization of the industrial infrastructure and ensure that investors have access to the reliable information about the natural and resources potential of the region and its ecological situation.
Methods. The study is based on the systems analysis. The emergence principle, also known as the principle of irreducibility, i.e. properties of a whole are not equal to a sum of properties of its components, in our opinion, may serve as means of guidance in use of natural and resource potential in order to face challenges of investing in a specific region.
Results. We assessed the stock of the main natural resources types and revealed that the region’s environment severely suffered from the depletion and pollution aggravated by a growth in the consumption of natural resources consumption grows.
Conclusions and Relevance. It is necessary to boost investment not only in projects for further use of natural resources but also in priority programs aiming at the recovery and preservation of the environment.
“…The natural zeolites are used mainly as dietary supplements, ion exchangers, and in environment remediation, while the synthetic zeolites are used mainly as detergent builders, catalysts, and absorbents or desiccants [6,7]. Recently, zeolites have attracted significant interest due to their ion exchange capacity, crystallinity, thermal stability, and well-defined cage structure, making them good candidates for a wide range of promising applications in the fields of water purification, fuel cells, renewable energy production, and storage [8][9][10].…”
This study presents the effect of thermal treatment (450, 500, 600, 750, and 800 °C) on a Romanian clinoptilolite-rich natural zeolite, along with the interaction of raw and thermally treated zeolites with simulated gastric fluid (SGF, pH = 1.20) at different zeolite to SGF ratios and exposure times. The zeolites were characterized using gravimetric analysis, X-ray fluorescence, powder X-ray diffraction (pXRD), and Fourier transform infrared (FT-IR) spectroscopy. The chemical composition of the zeolite subjected to thermal treatment did not change significantly with the increase of temperature. Structural changes were not detectable by pXRD and FT-IR analyses in the zeolites thermally treated up to 500 °C, while above 600 °C a gradual structural breakdown of zeolite was noticed. At high temperatures, the broad, low-intensity peaks in pXRD patterns indicated the partial amorphization of the crystalline structure. The pXRD and FT-IR analyses showed that the crystalline structure of zeolites remains unaffected after their exposure to SGF. The results revealed that the amounts of Fe, Na, Mg, K, Ca, Al, and Si released depends mainly on the zeolite to SGF ratio, and to a lower extent on the thermal treatment temperature, while the exposure time of 1 to 7 days does not have a significant impact on the elements released in SGF.
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