Cation Exchange Capacity Of Zeolite Research Articles

Paraffin-Coated Hydrophobic Hemostatic Zeolite Gauze for Rapid Coagulation with Minimal Adhesion.

To solve the problem of strong adhesion and excessive blood loss caused by the use of hydrophilic zeolite gauze (Z-Gauze) in uncontrollable bleeding, we have modified the surface of commercial Z-Gauze with a paraffin coating and prepared a hydrophobic dressing PZ-Gauze. After paraffin coating, the adhesion of Z-Gauze was reduced without an obvious decrease in coagulation activity. The clotting time of the hydrophobic PZ-Gauze was reduced from 378.3 to 154.6 s compared with that of cotton gauze, and the peeling force was decreased from 348.8 to 84.7 mN compared with that of Z-Gauze. Besides, PZ-Gauze can efficiently cut down the blood loss during treatment. On the basis of in vitro and in vivo experiments, it is confirmed that surface hydrophobic modification does not change the procoagulant performance because of the maintained cation exchange capacity of zeolites, and the reduced blood loss as well as enhanced difficulty for fibrin adhesion is attributed to its hydrophobicity. This is different from the traditional gauze procoagulant theories, where gauze hydrophilicity and procoagulant performance are always positively correlated.

Synthesis and cation exchange capacity of zeolite W from ultra-fine natural zeolite waste

This study synthesized zeolite W from waste natural zeolite powder. Activation of natural zeolite was required if zeolite W was to be created. Although thermal treatment at 400 to 900 °C made amorphous meta-zeolite, the amount of crystalline zeolite formed was limited to 36.5 wt%. Moreover, chabazite was also present (up to 30.4 wt%) with the extent dependent upon whether stirred or static synthesis conditions were employed. Regardless, thermal treatment of natural zeolite did not significantly improve zeolite W formation compared with synthesis from “as received” natural zeolite. In contrast, alkali fusion at 600 °C for 4 h activated the majority of aluminium species and <40 wt% of silica species. Consequently, the amount of crystalline zeolite W made was promoted; especially when the reaction mixture was agitated. The preferred reaction temperature was 150 °C; as below this value there was rapid decrease in zeolite W content and enhancement of zeolite L production. Reaction time was as short as 16 h, which was relatively fast compared to literature values. Similarly, a SiO 2 /Al 2 O 3 ratio of > 3 was required if zeolite W was to be synthesized rather than zeolite L. Notably, if the SiO 2 /Al 2 O 3 ratio was increased to >5.88 then the presence of zeolite W was reduced. Preferred H 2 O/SiO 2 ratio was related to the amount of KOH used in the fusion stage. The cation exchange capacity of 324 meq/100 g suggested that this material may be suitable for a range of ammonium based environmental remediation problems • First transformation of waste natural zeolite powder to zeolite W. • Fusion activation of natural zeolite better than thermal treatment. • Identified preferred synthesis conditions for zeolite W. • Highest reported cation exchange capacity for zeolite W.

Removal of water hardness using zeolite synthesized from Ethiopian kaolin by hydrothermal method

Abstract The use of low cost materials in zeolite synthesis becomes an area of important interest in water softening. This research is aimed to utilize kaolin for zeolite synthesis with hydrothermal method. Mechanical, thermal chemical treatments of raw kaolin were used for zeolite synthesis. Fourier Transform Infrared Spectrometry (FTIR), AAS, XRD, surface area (BET), differential scanning calorimetry and TGA were used to characterize kaolin and zeolite and UV–VIS/spectrometer were used for adsorption capacity of ion exchange. Effect of contact time, pH solution and temperature of the solution were studied for batch experiments. XRD values indicated that the prepared material is showed as fully crystalline and primarily amorphous. Before and after hardness removal sample transmittance percentage intensity showed a wide range of difference. From this study, it can be deduced that Zeolite can be used as a low cost water softening agent. At room temperature, the residue is well with calcium and badly with magnesium, whereas affinity toward Mg ions increases to acceptable levels at 60 °C. The cation exchange capacity of zeolite was found to be dependent on contact time. The batch experiments of removing Ca2+ and Mg2+ show that the adsorption capacity of zeolite in calcium ion is higher affinity than magnesium ion.

제올라이트의 양이온 교환 용량 및 용액의 화학적 특성에 따른 박테리아의 거동 특성 비교

제올라이트의 양이온 교환 용량 및 용액의 화학적 특성에 따른 박테리아의 거동 특성 비교

Cation Exchange Capacity of Zeolite X from Bagasse Ash against Magnesium(II)

&lt;p class="BodyAbstract"&gt;Water is a substance crucial for human life and industries. The good water must be fulfill some criteria, such as absence of Ca&lt;sup&gt;2+&lt;/sup&gt; or Mg&lt;sup&gt;2+&lt;/sup&gt; cations. The cations can be reduced by ion exchange process. This study used synthesized zeolite X from bagasse ash as cation exchange for Mg&lt;sup&gt;2+&lt;/sup&gt;. Mg ion was used as standard to determine hardness of water by EDTA titration. The analysis showed cation exchange capacity of zeolite X with molar ratio of Si/Al 1; 1,5 and 2 was 1,9. The value indicated zeolite X have high capability as cation absorbents for Mg&lt;sup&gt;2+&lt;/sup&gt; ion.&lt;/p&gt;&lt;p class="BodyAbstract"&gt; &lt;/p&gt;&lt;strong&gt;&lt;em&gt;Keywords:&lt;/em&gt;&lt;/strong&gt;&lt;em&gt; bagasse ash, cation exchange capacity, magnesium(II), water hardness, zeolite X&lt;/em&gt;

Amine-functionalized, silver-exchanged zeolite NaY: Preparation, characterization and antibacterial activity

Amine-functionalized, silver-exchanged zeolite NaY (ZSA) were prepared with three different concentrations of 3-aminopropyltriethoxysilane (APTES) (0.01, 0.20 and 0.40M) and four different concentrations of silver ions (25%, 50%, 100% and 200% from zeolite cation exchange capacity (CEC)). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), surface area analysis, thermogravimetric analysis (TGA) and zeta potential (ZP) analysis. The FTIR results indicated that the zeolite was functionalized by APTES and that the intensity of the peaks corresponding to APTES increased as the concentration of APTES used was increased. The antibacterial activities of the silver-exchanged zeolite NaY (ZS) and ZSA were studied against Escherichia coli ATCC11229 and Staphylococcus aureus ATCC6538 using the disc diffusion technique (DDT) and minimum inhibitory concentration (MIC). The antibacterial activity of ZSA increased with the increase in APTES on ZS, and E. coli was more susceptible towards the sample compared to S. aureus. The FESEM micrographs of the bacteria after contact with the ZSA suggested different mechanisms of bacterial death for these two bacteria due to exposure to the studied sample. The functionalization of ZS with APTES improved the antibacterial activity of the silver-zeolite, depending on the concentration of silver ions and APTES used during modification.

Decrease in Cation Exchange Capacity of Zeolites at Neutral pH: Examples and Proposals of a Determination Method

Cation exchange capacity (CEC) is an important characteristic of zeolites, especially when they are used as adsorbents in the aqueous system. However, no international standard method exists for the determination of CEC of zeolites. We determined CEC of Linde-type A and Na-P1 type zeolites at various pH (4 to 10) with a simple method, where Na+-saturated zeolites were prepared, and then various amounts of HCl were added. CEC was simply calculated by subtracting the amount of Na+ in the final supernatant from the content of Na+ of the Na+-saturated zeolites. CEC of the zeolites decreased with decreasing pH and with decreasing Na+ concentration of the final supernatant. The concentration of Na+ of the supernatant, CEC of the zeolites began to decrease at weakly alkaline or neutral pH, and that of the Linde-type A zeolite became about half at pH around 6. When CEC was plotted against pH-pNa; where pNa is negative logarithm of the activity of Na+; CEC of each zeolite was expressed by a curve. It indicates that the CEC or the amount of Na+ retention is univocally determined by the ratio of activities of Na+ and proton.

Synthesis of FAU Type Zeolite Y from Natural Raw Materials: Hydrothermal SiO2-Sinter and Perlite Glass

The first synthesis of pure FAU-type zeolite Y from a SiO2-sinter and perlite glass is presented. FAU-type Zeo- lite Y was synthesized at 95 ± 2°C after 6-12 hours using gels having SiO2:Al2O3:Na2O molar ratios of 8.4:1:4.2 and using gels with SiO2:Al2O3:Na2O molar ratios of 10.5:1:4.2 between 48 and 120 hours reaction time. Except for zeolite Y, zeo- lite NaPc, gmelinite-Na and the OH-analogue of sodalite were produced from starting gels with different composition. The cation exchange capacity of zeolite Y was 3.3 meq.g -1 and its specific surface area was 520-550 m 2 .g -1 . Most of the spe- cific surface area is allocated to micropores. Zeolite Y synthesized from gels with a SiO2:Al2O3 molar ratio of 10.5:1 has a lattice parameter parameter ao = 24.747 A and a Si/Al ratio 2:1. It is concluded that inexpensive raw materials such as vol- canic glasses can be used for the production of high added value zeolite Y.

Effect of some additives on synthesis of zeolite from coal fly ash

Hydrothermal conversion of fly ash into zeolites was conducted and the effects of the addition of sodium halide and waste solutions produced after zeolitization of fly ash, as well as the adjustment of the Si/Al ratio prior to synthesis process on the formation and cation exchange capacity (CEC) of zeolite product were evaluated. Both the addition of NaCl and NaF ameliorated the crystallinity and CEC of synthesized zeolite, but NaF had a better improvement effect. Na + was considered to enhance the crystallization of zeolite, while F − favored the dissolution of fly ash. The type of zeolite formed depended on the Si/Al ratio of the starting material prior to the nucleation and crystallization of zeolite. The adjustment of the Si/Al ratio of fly ash by addition of Na 2SiO 4 and Al(OH) 3 changed the type and CEC of zeolite. Waste solutions contained large amount of Si and little Al due to the formation of a zeolite named NaP1 in zeolite terminology with the Joint Committee of Powder Diffraction Standard (JCPDS) code of 39-0219. The alkalinity decreased largely. As a result, the CEC value of zeolite products synthesized with waste solution as alkali source decreased. The supplementation of new alkali to adjust the alkalinity of waste solution could enhance the CEC of synthesized product. It was concluded that: (1) addition of sodium halide and adjustment of the Si/Al ratio prior to synthesis can improve the quality of zeolite; (2) waste solutions produced following the zeolitization of fly ash can be reused as an alkali source in the activation of fly ash; zero-emission of waste solution in the synthesis of zeolite from fly ash is possible.

The investigation on cationic exchange capacity of zeolites: The use as selective ion trappers in the electrokinetic soil technique

The cation exchange capacity (CEC) of porous zeolites allows to adsorb in the framework cavities the cations as pollutant heavy metal ions. We investigate the CEC behaviour of different zeolites in different experimental conditions; in solution where the ion's mobility is spontaneous and free and in the electrokinetic system where the ion's mobility is driven by the electric field. The aim of this study is to investigate if the CEC is an useful property to create a special interface region of zeolites, that if placed in the electrokinetic cell, just before the cathode, could allow to capture and concentrate the heavy metallic ions, during their migrating process. The zeolite 13X investigated in the electrokinetic proofs, retains a good high ions adsorption, even if quite smaller than the relevant free solution condition and well acts as confined trap for the heavy metal ions. In fact no trace of metallic deposition are present on the electrode's surface.

Effects of zeolites on cultures of marine micro-algae

The cation-exchange capacity of zeolites is well known and has been increasingly explored in different fields with both economic and environmental successes. In aquatic medium with low salinity, zeolites have found multiple applications. However, a review of the literature on the applications of zeolites in salt waters found relatively few articles, including some recently published papers. The purpose of this review is to present the state-of-the-art on applications of using zeolites for amending the trace elemental contents of salt water as well as the implications of this property for promoting marine micro-algal growth. This paper deals with the following features: Sorption capacity of zeolites including 1. application of zeolites in saltwater, 2. the role of silicon and zeolites on cultures of micro-algae, and 3. the role of organically chelated trace metals. The following competing factors have been identified as effects of zeolites on algal growth in salt water: (i) ammonia decrease: growth inhibition reduced; (ii) macro-nutrients increase, mainly silicon: stimulation of silicon-dependent algae; (iii) trace metals increase (desorption from zeolites) or decrease (adsorption): inhibition or stimulation, depending on the nature of the element and its concentration; and, (iv) changes in the chelating organics exudation: inhibition or stimulation of growth, depending on the (a) nature of the complexed element; (b) bioavailability of the complex; and (c) concentration of the elements simultaneously present in inorganic forms. Zeolites have been capable of stimulating the growth of the silicon-demanding marine micro-algae, like diatoms, mainly because they can act as a silicon buffer in seawater. Zeolites can also influence the yield of non-silicon-demanding algae, because the changes they can cause (liberation and adsorption of trace elements) in the composition of the medium. Zeolites have been capable of stimulating the growth of the marine micro-algae. However, the extent of ion exchange between zeolite and seawater, which conditions the effects, will depend on several factors: (1) initial metal concentration in seawater; (2) levels of trace metals in the zeolites (contaminants); (3) characteristics of the zeolites in terms of both ion-exchange capacity and specific affinities for the different cations; (4) quantity of zeolite per litre of solution; (5) pH and (6) response of the organism in terms of liberation of organic ligands. Therefore, a previous investigation in each particular case is recommended, in order to select the zeolitic characteristics and concentrations that will maximize the algal yield. Stimulation of phytoplankton growth can be economically relevant since phytoplankton constitutes the basis of the marine food webs and is required in fish farming nurseries in the marine aquaculture industry. Zeolites are cheap, only small amounts (few milligrams per liter of culture) are required and the addition of some micro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may have economic advantages.

The comparative ion exchange capacities of natural sedimentary and synthetic zeolites

A large tonnage of natural, sedimentary zeolites is found in the Western United States and world-wide. They offer a substantial potential for a variety of industrial uses including the removal of cations from acid mine drainage and industrial waste waters. There is a wide variation in the cation exchange capacity of zeolites because of the differing nature of various zeolite cage structures, natural structural defects, adsorbed ions, and their associated gangue minerals. In general, the effectiveness of several natural and synthetic zeolites has been found to be: Erionite > 13X > Chabazite > Clinoptilolite > > Mordenite ⋟ 3A ⋟ 4A ⋟ 5A where 3A, 4A, 5A and 13X are synthetic zeolites. The approximate order of effectiveness for cation removal from pristine solutions is: Ag + > Pb +2 > Cd +2 > Zn +2 ≥ Cu +2 > > Ni +2 > Hg +2 A pre-exchange process with strong Na + solutions can remove deleterious exchangeable cations from the natural zeolites and can significantly improve their cation exchange capacity. The uptake of heavy metal ions has been studied using both the batch and column techniques, and the exchange capacities of ‘as received’, beneficiated and pre-exchanged zeolites have been evaluated. Electron microprobe studies have shown the reason for the relatively poor ion exchange performance of the synthetic zeolites to be due to a diffusion problem. A means of mitigating the problem for the 13X zeolite is given.