Papers by Keyword: Zeolite

Abstract: Ball milling is a top down approach and a method to reduce size of particle while Zeolite is a valuable inorganic materials having wide variety of applications. In this paper, ball milling of commercial synthetic Zeolite powder was studied with their time varied. Wet ball milling was selected as a potential means to decrease the particle size of Zeolite over dry grinding. The parameters that included in this study were rotational speed, balls to powder ratio, water to powder ratio and milling time. These nanozeolite were characterized via Zeta-sizer nanoseries of particle sizer, FESEM, and also FTIR. Results showed that commercial synthetic Zeolite powder with particle size larger than 45 μm may be reduced into the size range between 0.2 0.3 μm by planetary ball mill.

Abstract: A better understanding of the adsorption behaviors of hydrocarbons on adsorbent would help trap the hydrocarbons emitted from diesel engines during cold start period more efficiently. In this paper, the adsorption behaviors of hydrocarbons in LTA zeolite was studied using Grand Canonical Monte Carlo (GCMC) simulation. The adsorption isotherms and mass clouds are obtained for both pure component and binary mixtures under certain temperatures. The adsorption isotherms reveal that the average loading of ethylene and propylene has the similar trend. Both of them increase with the increase of pressure and decrease significantly with the increase of temperature. The binary mixtures show competitive adsorption behavior. Propylene is adsorbed much more strongly than ethylene in LTA zeolite. The obtained mass clouds show that propylene distributes in both the α cage and β cage of the LTA zeolite, while ethylene distributes mainly in the β cage of the LTA zeolite.

Abstract: The performance of three BAFs with zeolite, activated carbon and anthracite media for the treatment of polluted Huaihe raw water were investigated. All three BAFs performed promising permanganate index (COD_Mn) and ammonia nitrogen (NH₄⁺-N) removal efficiency as well as the turbidity removal was over 60%. Moreover, the COD_Mn and NH₄⁺-N removal in the three BAFs were affacted by the characteristics of filter media. Activated carbon and anthracite had better COD_Mn removal than zeolite. Zeolite had the best NH₄⁺-N removal, followed by activated carbon, anthracite was the worst.

Abstract: This article discusses the thermophysical properties of zeolite-based adsorbents. Three types of zeolite (Z-01, Z-02 and Z-05) with different chemical compositions developed by Mitsubishi Plastics, Inc. are analyzed for possible applications in adsorption chillers and desalination cycles driven by low-temperature waste heat sources. The experiments are performed using static volumetric method with N2 gas sorption at 77 K. Thermophysical properties such as pore surface area, micropore volume and pore size distribution are evaluated using standard multi-point Brunauer-Emmett-Teller (BET) and Non-Local Density Functional Theory (NLDFT) methods. It is observed that Aluminosilicate functionalized Z-02 exhibits the highest surface area with huge micropore volume.

Abstract: Lime, a traditional calcium based stabilizer, had been widely used in chemical stabilization to improve the strength of soil. Past researches had shown that the major reaction product of lime and soil such as Calcium Silicate Hydrate (CSH) was formed abundantly under the observation of microscopic studies. However, sometimes it will be quite difficult to confirm the existence of CSH phase if solely based on its needle like structures, especially when other rod like structures will also exist. Practically, the recognition of the CSH phase by using XRD spectrum through matching with published data had speed up the process of identification. If the method is viable, then theoretically, the molecular weight ratio of silica and calcium, S/C of CSH gel is specific and can be determined based on its possible chemical compound. Hence, this study was carried out in an attempt to examine the possibility use of its S/C ratio as a quick method to confirm the existence of CSH gel. Two types of artificial organic soils were formed by admixing kaolin (inorganic matter) and humic acid (organic matter) with the ratio of 7:3 and 5:5. Four types of admixtures with different percentages ratio of lime and zeolite (a kind of pozzolan) were used to stabilize the soils. The specimens were cured at elevated temperature of 50°c in order to accelerate the development of reaction products. Field Emission Scanning Electron Microscope with attached Energy Dispersive Analyzer (FESEM-EDX) was utilized to observe and determine the existence of reaction products and its bulk chemical composition. The S/C ratio of needle like structures were determined and it is found that the S/C ratio fluctuates and varies significantly from one specimen to another. It is believed that due to the limitations of the experimental setup, the EDX analysis can only serve as semi-quantitative and act as a reference guide on the existence of element. Despite of its limitations, the EDX analysis is useful in distinguish the CSH from other structure which is physically un-identical.

Abstract: Three columns filled with multi-size combined medium were utilized in the simulative vertical-flow constructed wetland systems to treat wastewater at hydraulic loading rate of 2000-3000 mm/d, that the same kind of media including biological ceramsite, anthracite and zeolite in each column. Comparative analyses were made in treatment performances between multi-size medium and single medium. The results showed that compared with the treatment performances of single medium, the purifying effect had great influence by the multi-size combined medium which were made up of same kind and different size of filter medium. Contrast with the corresponding single medium, the average removal efficiencies of COD_Cr, Total Nitrogen (TN), and Total Phosphorus (TP) were increased obviously which were purified by the multi-size combined medium. Good performances were achieved in terms of removal of BOD₅ and COD_Cr in the column of multi-size combined biological ceramsite medium. The average removal efficiencies of TN were great in the column of multi-size combined zeolite medium. Good performances were also achieved in terms of removal of TP in the column of multi-size combined anthracite medium.

Abstract: A modified Zeolite to be prepared and its performance of removing fluorine from containing fluoride water was reported. Firstly, using zeolite 4A as skeleton, by means of carrying to adsorb Fe^3﹢from containing ferri ions solution, which the zeolite can be modified and the coordination metal center are formed. Based on mechanism of ligand exchange, a new material of removing deeply fluorine from water was got. Secondly , the results show that this modified zeolite has favourable adsorbing capacity for fluorine from water, when fluorine concentration is about 4～25 mg.L^-1, above 99.0% of fluorine can be removed from water. The static saturation adsorbing capacity is 20.1 mg.g^-1, by following conditions:the pH of water range of 5-8; solid-to-liquid ratio of 1:50 and room temperature.Common-ions in water do not make affect to adsorbing fluorine by the zeolite and high selection in process of removing fluorine has been demonstrated.

Abstract: This paper presents the structure for a rotary six-bed adsorber that carries out a six-step PSA continuous oxygen generation process with a short cycle time and a low operation pressure ratio. The working principle of a rotary six-bed PSA oxygen generator is introduced and the effects of various operating parameters on PSA performance are experimentally investigated. The results indicate that, the adsorption pressure increases with the reduction of rotating speed and decreases with the lowering of the feed flow rate; with the acceleration of rotating velocity, the oxygen purity of the gas produced first rises and then drops, and it has an optimum rotating velocity; the higher the feed flow rate, the lower the oxygen purity of the product; the ratio of the pressurization angle to the adsorption angle has a remarkable effect on the oxygen purity with the oxygen purity increasing according to the condition of keeping the angle of the feeding ring groove and with the increase in this ratio; and the long-purging time at a low purging-gas flow rate is appropriate for miniature apparatus.

Abstract: The removal efficiencies for ammonium (NH₄⁺) and total phosphorus (TP) from runoff using two layered filtration systems (LFS-A, with a turf surface, and LFS-B, with a permeable brick surface) were investigated in six repeated experiments. The results indicated that the removal efficiencies for NH₄⁺ and TP from infiltrated water using LFS-A were as high as 90.92 and 91.60%, respectively, while the efficiencies resulting from LFS-B ranged from 86.67 to nearly 100% and 90.29 to 99.09%, respectively. However, there was a significant difference in the comprehensive removal rates (CRRs) for NH₄⁺ and TP between LFS-A (400 and 70 mg·m^-2·h^-1, respectively) and LFS-B (174 and 54 mg·m^-2·h^-1, respectively). Some engineering measures, such as the utilization of replanted turf, may reduce the CRRs for pollutants for long periods of time; while no significant relationships between the CRRs of NH₄⁺ and TP and their initial concentrations were observed.

Abstract: Organic content in soil is believed to inhibit formation of reaction products in lime stabilization which resulted in low gain of strength when dealing with organic soils. Zeolite, a kind of pozzolan with high CEC capacity is proposed to be use in this study in order to improve lime stabilization of organic soil. The effectiveness of blended lime zeolite in stabilization of organic soils was investigated by using two types of artificial organic soils with predetermined organic contents. Artificial organic soils were formed by mixing inorganic soil (commercial kaolin) with organic matter (commercial humic acid) at specific ratio. Initial consumption of lime for organic soils was determined in order to determine the minimum percentage of stabilizer required for each soil. Potential influencing factors that might affect the strength such as organic contents, contents of stabilizer, and curing periods were studied. The findings of the study showed that high organic contents and low lime contents resulted in lower gain of strength. However, it is found that slight replacement of lime with zeolite works well with low organic soil at long curing period which resulted in highest strength among all the mixes. Overall, longer curing periods will increase the strength of the soil in the order of 56 days > 28 days > 7 days. Nevertheless, the percentage of strength increment over curing periods is linear with the lime contents, which proved that lime is required for pozzolanic reaction.