Papers by Keyword: Zeolite

Abstract: The paper presents the study of the absorption mechanism of organic pollutants such as formaldehyde and oxalic acid by natural zeolite and peat materials modified by iron (III) ions using the limited volume method.The relevance of this paper is a search for the use of inexpensive and available natural sorbents for waste water purification from ecologically hazardous water-soluble organic pollutants. The impact produced by the solution concentration and temperature and the size of natural composite particles on the sorption rate of organic substances is described in this paper. The effective factors for diffusion and energy of the process activation are calculated. It is found that the mixed-diffusion kinetics is the determinant stage of the process. In case of peat and zeolite composites, the internal diffusion prevails in the mixed-diffusion kinetics.

Abstract: In this study, the ability of treated oil palm ash aided with kaolin powder to produce zeolites is studied. The palm ash has been treated with citric acid via a leaching process to get rid of the metallic impurities in it. The usage of treated oil palm ash in the zeolites conversion seems to be an option for waste materials management. Characterization of treated oil palm ash from Malaysia’s palm oil plantation has been cleared. The treated oil palm ash and kaolin powder are used as the starting material for the synthesis of zeolites materials. The method chose for the zeolites conversion is alkaline hydrothermal treatment. The chemical composition, crystalline phases and elemental composition of treated oil palm ash and as-synthesized samples were characterized and studied. From the analysis, the treated oil palm ash was a fertile source of silica and exists as quartz phase. The outcomes have significant motivation for the production of zeolites by using low cost material such as treated oil palm ash.

Abstract: Silantek clay deposits were characterized and evaluated for their potential as structutral ceramic products raw materials through chemical, mineralogical and refractory (1250 to 1600^o C) properties determinations. Results show that the main oxides in the samples were SiO₂ and Al₂O₃, whereas the other oxides present only in small quantity. Kaolinite(Al₂Si₂O₅(OH)₄) and quartz(SiO₂) present as dominant mineral phases and the minor phases of mullite(Al₆Si₂O₁₃) and zeolite(Na₂Al₂Si₃O₁₀·2H₂O) also appeared in the samples. From the results of the refractoriness tests up to 1600°C, samples ST11, ST23A, ST31A, ST31B, ST33 have potential for refractory products as they demonstrated high thermal resistance properties(over 1600°C). Silantek clay potential to be used as raw materials mainly for refractory, structural ceramics and other common ceramic products

Abstract: Permeable reactive barriers (PRBs) are passive, in-situ remediation systems that comprise the filtration of a contaminated groundwater through a reactive media able to degrade, adsorb or precipitate the pollutants. Selection of the reactive media depends on the nature of the contamination. While the majority of PRBs are used to treat groundwater contaminated with chlorinated volatile organic compounds or acid mine drainage, the present study is focused on heavy metals, namely Fe, Al, Cu, Ni, Zn, Mn and As. To remove such inorganic pollutants, four methodologies are usually implemented: a) redox reaction, b) adsorption and ion exchange, c) biological treatment (e.g. metal sulphides precipitation) and d) pH control and precipitation. The present paper deals with the last methodology in which an adjustment of pH by alkalinity-generating materials leads to the precipitation of metal hydroxides and the decrease in the concentration of dissolved species. As the solubility of metals depends on their valence, redox-potential, concentrations and kinetics of reaction, the target pH varies with respect to the considered metal. A pH of about 10 allows the precipitation of hydroxides of divalent ions (zinc, manganese, copper, lead, nickel, cobalt and cadmium), while a pH of around 6-7 is adapted to trivalent ions (iron, aluminium and chromium). However, the accumulation of precipitates in the pore spaces can cause clogging of the pores, hence decrease the porosity and hydraulic conductivity of the reactive media and alter its efficiency. To validate this assumption, the neutralizing ability of alkaline materials such as activated zeolite and magnesite were examined in a test column by monitoring the resultant pH with attention to impact of precipitates on the hydraulic properties of reactive materials. Based on the test results, both materialls are considered suitable to remove the groundwater contaminants with high efficiency (up to 99%) and suitable grain size to encourage flow through the PRB.

Abstract: Industrial wastewater treatment and reuse is one of the principal tasks of present. For this purpose several physical, chemical and combined methods have been used. This paper deals with the study of sorption behaviour of natural zeolite with respect to Zn (II) and Cu (II) followed by cross-flow membrane microfiltration. The experiments realised were aimed at verification of effectiveness of ion exchange of selected metals from wastewater using zeolite – with main component clinoptilolite. The experimental data obtained were fitted using Langmuir and Freundlich isotherms. The sorption capacity was studied for zinc and copper uptake, followed by a study of microfiltration of zeolite suspension using a cross-flow microfiltration device with tubular ceramic membrane. According to experimental results the basic parameters of microfiltration process were evaluated. In comparison with other processes, the hybrid membrane microfiltration offers more effective way of water treatment.

Abstract: Linuron and atrazine as a kind of pesticides were used more widely in agriculture. The toxic effect in the environments, which accumulation in soil, water and human effect. Both of pesticides were adsorped using zeolites with batch method. Three difference types of zeolite were used for comparison. Those pesticides consisted of various Si/Al ratio which were 3.61 (Y), 8.61 (Y-10) and 111.35 (Y-100). The organo-zeolite, which modified with hexadecyltrimethyl ammonium (HDTMA) surfactant were used for comparison. It was found that the adsorption capacity of linuron more than atrazine 30 % for Y , 40 % for Y-10 and 10 % for Y-100. It can be explaned that the small molecules of linuron (thickness 6.12 Ao) could move onto pore size of zeolite (7.4 A^o). While the larger molecules of atrazine (thickness 9.6 A^o) could not do this. The maximum asorption capacities of all pesticides are Y-100 and MY-100 because they have most external area and hydrophobic properties which were form their most dealuminative potential. The comparison of MY-10 and Y-10 found that MY-10 has more adsorption capacities than Y-10 as follow 4 % for linuron and 20 % for atrazine since MY-10 has more increased hydrophobic force. Adsorption capacity of MY-100 is similar to Y-100. Adsorption capacities of MY is lower than Y since it has steric effect and pore blocked with surfactant. This results were identified by XRF, XRD, FT-IR, TGA and CHNS.

Abstract: Water abstraction for water treatment of portable water especially riverbank filtration (RBF) is essential to be safe and clean. Due to the awareness towards the spread of contaminants and deterioration of water resources, the needs of artificial barrier is seen as crucial. An artificial barrier is a man-made vertical barrier to pre-treat the abstraction water from the water intake structure. The proposed artificial barrier is a mixture of sand (local soil), granular activated carbon (GAC) and zeolite. In this study, the three adsorbents were tested for their adsorption and permeability. The effects of adsorbent dose on the adsorption of the turbidity, iron and zinc were investigated. After treatment with sand, the levels of turbidity, iron and zinc were observed to decrease by 93.7%, 85.15% and 68.5%, respectively. For GAC, the levels of turbidity, iron and zinc decreased by 96.9%, 99.2% and 36.3%, respectively. The reduction on the levels of turbidity, iron and zinc was preferable by zeolite with 98.3%, 93.0% and 98.8%, respectively. By using Langmuir and Freundlich adsorption isotherm, the result indicated that the adsorption of adsorbents mostly obeyed Freundlich model. The relationship is an empirical equation which has an asymptotic maximum as pressure increase without bond.

Abstract: Different methods are used to prepare gallium-containing zeolites of a ZSM-5 structure. Their acidic and structural characteristics are investigated and the effect of the method of gallium introduction into a zeolite on distribution and ratio of acid sites of different strengths, as well as on pore volume and diameter is determined. The relationship between the localization of gallium introduced into a zeolite by different methods and its electronic state and the catalytic activity and selectivity of the resulting contacts in the course of propane aromatization is established. The Ga-containing zeolite prepared by impregnation is found to be the most efficient catalyst for conversion of propane into aromatic hydrocarbons.

Abstract: The present study compares the photocatalytic decolorization ability of Fe-doped ZnO modified both natural zeolite and montmorillonite towards aqueous solution of organic dyes such as methylene blue and methyl orange under UV light irradiation. Both photocatalysts were synthesized using co-precipitation method and characterized by X-ray diffraction, energy dispersive X-ray, Fourier-transform infrared absorption, and electron spin resonance spectroscopy. The results showed that the photocatalytic efficiency is better in the presence of montmorillonite compared to natural zeolite.

Abstract: Activated carbon, zeolite and titanium dioxide are wildly used for removing the organic compounds in waste water. Although, these materials exhibit high performance (in powder form), reclaiming of these materials from the waste water treatment system is still hard. The objective of this study is to fabricate hollow cylinder activated carbon-zeolite samples which were used as a porous substrate. Various ratios of activated carbon, zeolite NaA and clay were mixed with special binder to form dough before extruded to be hollow cylinder shape. The hollow cylinder samples were cut into 2.5 cm long and then were fired at 600 °C for 2 hours under 5%CO₂+N₂ atmosphere. The fired samples were dip-coated with TiO₂-P25 and fired at 600 °C for 1 hour under 5%CO₂+N₂ atmosphere for testing the photocatalytic degradation of lignin solutions under UV light. The results showed that the strength of fired samples increasing with the ratio of clay increased. The XRD patterns of samples having clay addition showed peaks of zeolite and quartz. The physical properties, microstructure and photodegradation will be discussed.