scholarly journals Propiedades Básicas de Zeolitas Naturales de Panamá con Potencial de Desarrollo Industrial

2018 ◽  
Vol 3 (1) ◽  
pp. 721
Author(s):  
Dr. Cecilio Hernández B. ◽  
M.Sc. Jorge Olmos ◽  
Licda. Yahaira Espinosa
Keyword(s):  
Chemical Composition ◽  
Physicochemical Properties ◽  
Cation Exchange ◽  
Volcanic Activity ◽  
Natural Zeolite ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Natural Zeolites ◽  
Low Levels ◽  
Initial Results

The initial results of the properties that have been determined to a sample of natural zeolite, coming from areas of volcanic activity of Panama, and that has been identified with potential for its industrial explotation, are presented. Some physicochemical properties, chemical composition and morphology were determined. A natural zeolite with an intermediate level of Si/Al (2.62), low levels of dissolved salts and a morphology with pores-shaped channels with a diameter of 5 mm are observed.Keywords: natural zeolites, chemisorption, morphology, macropores, cation exchange capacity

scholarly journals PREPARATION OF SOME VIETNAMESE MONTMORILLONITES

2010 ◽  
Vol 13 (1) ◽  
pp. 17-21
Author(s):  
Mai Thi Hoang Vo ◽  
Thach Ngoc Le
Keyword(s):  
Chemical Composition ◽  
Physicochemical Properties ◽  
Cation Exchange ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Crystalline Structure ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Solid Catalyst

Montmorillonite is a "green" solid catalyst and support used in many organic reations. In this paper, we describe the method to prepare two acid-activated montmorillonites from Binh Thuan and Lam Dong clays. We still prepared some cation exchanged montmorillonites as Fe3+ Zn 2+ and Al 3+. The Vietnamese montmorillonites and K-10, KSF (two commercial Fluka montmorillonites) were determinated simultanneously on some physicochemical properties such as crystalline structure, chemical composition, cation exchange capacity, adsorption capacity, porisity, surface area and acidity. The results shows that the quality of Vietnamese montmorillonites are equivalent with K-10 and KSF.

scholarly journals Effect of Low Zeolite Doses on Plants and Soil Physicochemical Properties

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2617
Author(s):  
Alicja Szatanik-Kloc ◽  
Justyna Szerement ◽  
Agnieszka Adamczuk ◽  
Grzegorz Józefaciuk
Keyword(s):  
Plant Growth ◽  
Physicochemical Properties ◽  
Cation Exchange ◽  
Surface Area ◽  
Cation Exchange Capacity ◽  
N Fertilization ◽  
Exchange Capacity ◽  
First Year ◽  
Soil Physicochemical Properties ◽  
Water Holding

Thousands of tons of zeolitic materials are used yearly as soil conditioners and components of slow-release fertilizers. A positive influence of application of zeolites on plant growth has been frequently observed. Because zeolites have extremely large cation exchange capacity, surface area, porosity and water holding capacity, a paradigm has aroused that increasing plant growth is caused by a long-lasting improvement of soil physicochemical properties by zeolites. In the first year of our field experiment performed on a poor soil with zeolite rates from 1 to 8 t/ha and N fertilization, an increase in spring wheat yield was observed. Any effect on soil cation exchange capacity (CEC), surface area (S), pH-dependent surface charge (Qv), mesoporosity, water holding capacity and plant available water (PAW) was noted. This positive effect of zeolite on plants could be due to extra nutrients supplied by the mineral (primarily potassium—1 ton of the studied zeolite contained around 15 kg of exchangeable potassium). In the second year of the experiment (NPK treatment on previously zeolitized soil), the zeolite presence did not impact plant yield. No long-term effect of the zeolite on plants was observed in the third year after soil zeolitization, when, as in the first year, only N fertilization was applied. That there were no significant changes in the above-mentioned physicochemical properties of the field soil after the addition of zeolite was most likely due to high dilution of the mineral in the soil (8 t/ha zeolite is only ~0.35% of the soil mass in the root zone). To determine how much zeolite is needed to improve soil physicochemical properties, much higher zeolite rates than those applied in the field were studied in the laboratory. The latter studies showed that CEC and S increased proportionally to the zeolite percentage in the soil. The Qv of the zeolite was lower than that of the soil, so a decrease in soil variable charge was observed due to zeolite addition. Surprisingly, a slight increase in PAW, even at the largest zeolite dose (from 9.5% for the control soil to 13% for a mixture of 40 g zeolite and 100 g soil), was observed. It resulted from small alterations of the soil macrostructure: although the input of small zeolite pores was seen in pore size distributions, the larger pores responsible for the storage of PAW were almost not affected by the zeolite addition.

Characteristics of variably saturated granular bentonite after long-term storage at near-field relevant temperatures

Clay Minerals ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 343-361 ◽  
Author(s):  
M. Valter ◽  
M. Plötze
Keyword(s):  
Physicochemical Properties ◽  
Cation Exchange ◽  
Surface Area ◽  
Cation Exchange Capacity ◽  
Elevated Temperatures ◽  
Near Field ◽  
Exchange Capacity ◽  
Hydraulic Permeability ◽  
Cation Composition ◽  
Retention Capacity

AbstractBentonite is a potential material for use in the engineered barrier of radioactive waste repositories because of its low hydraulic permeability, self-sealing capability and retention capacity. It is expected that bentonite would react at the elevated temperatures accompanying the radioactive decay in the nuclear waste. The presented study was started in order to improve understanding of the coupled influence of temperature and (pore) water on the physicochemical and mineralogical properties of bentonite during thermal treatment under near-field relevant conditions. Granular Na-bentonite MX-80 was differently saturated (Sr = 1–0.05) and stored at different temperatures (50–150°C) in a closed system. Upon dismantling after different periods of time (3 to 18 months), mineralogical characteristics, cation exchange capacity and content of leachable cations, as well as physicochemical properties such as surface area and water adsorption were investigated.The results showed a high mineralogical stability. A slight conversion from the sodium to an earth alkali form of the bentonite was observed. However, considerable changes in the physicochemical properties of the bentonite were observed, particularly by treatment above the critical temperature of 120°C. The cation exchange capacity decreased during heating at 150°C by approximately. 10%. The specific surface area dropped by more than 50%. The water uptake capacity under free swelling conditions showed a slight tendency to lower values especially for samples heated for more than 12 months. The water vapour adsorption ability in contrast drops by 25% already within three months at T = 120°C. These changes are mostly related to the variations in the interlayer cation composition and to smectite aggregation processes. The observed alterations are rather subtle. However, temperatures ⩾ 120°C had a remarkable negative influence on different properties of MX-80.

Amorphous ferri-aluminosilicates in some tropical ferruginous soils

Clay Minerals ◽  
1976 ◽  
Vol 11 (2) ◽  
pp. 137-146 ◽  
Author(s):  
G. S. R. Krishna Murti ◽  
V. A. K. Sarma ◽  
P. Rengasamy
Keyword(s):  
Chemical Composition ◽  
Cation Exchange ◽  
Negative Correlation ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Molar Ratios ◽  
Silica Alumina ◽  
Fixation Capacity ◽  
Polymeric Component ◽  
Positively Charged

AbstractThe amorphous mineral selectively dissolved from the clay (<2 μm) fractions of twenty-six ferruginous soils contains considerable iron in addition to silicon and aluminium. SiO2/Al2O3 and SiO2/R2O3 molar ratios are between 2·03-3·52 and 1·72-2·95 respectively. The model of the amorphous ferri-aluminosilicate (AFAS) consists mainly of negatively charged tetrahedrally coordinated silica-alumina phase Si3AlO6(OH)4 containing domains of neutral FeOOH, with an outer positively charged hydroxyaluminium polymeric component [Al(OH)2.5]n.The calculated hydroxyl water content of the AFAS averages 17·8%; cation exchange capacity varies from 48·6 to 112·0 mEq/100 g and shows a negative correlation with the outer hydroxyaluminium octahedral component and a positive correlation with the ratio of the tetrahedral Si-Al component to the octahedral hydroxyaluminium component. The K-fixation capacity (1·9-6·1 mEq/100 g) of the AFAS does not appear to be related to the chemical composition. The genesis of the amorphous mineral is discussed.

scholarly journals Aflatoxin B1 adsorption by the natural aluminosilicates - concentrate of montmorillonite and zeolite

2016 ◽  
Vol 70 (5) ◽  
pp. 519-524 ◽  
Author(s):  
Marija Markovic ◽  
Aleksandra Dakovic ◽  
George Rottinghaus ◽  
Mirjana Stojanovic ◽  
Vera Dondur ◽  
...  
Keyword(s):  
Cation Exchange ◽  
Aflatoxin B1 ◽  
Natural Zeolite ◽  
Cation Exchange Capacity ◽  
Active Sites ◽  
Solid Phase ◽  
Bentonite Clay ◽  
Exchange Capacity ◽  
Composition Determination

Aflatoxin B1 adsorption by the concentrate of bentonite clay - montmorillonite and the natural zeolite - clinoptilolite and was investigated at the initial toxin concentration 4 ppm, with different amonunts of solid phase in suspension (10, 5, 2 and 1 mg/10 mL) and different pH values - 3, 7 and 9. Results indicated that for both minerals, decreasing the amount of solid phase in suspension, decrease the amount of active sites relevant for adsorption of aflatoxin B1. Thus, for concentrate of montnorillonite, at the lowest level of solid phase in suspension (1 mg/10 mL), aflatoxin B1 adsorption indexes were 97% at pH 3, 88% at pH 7 and 82% at pH 9, while for the natural zeolite, adsorption of toxin was 9% at pH 3 and 7% at pH 7 and 9. Since inorganic cations in minerals are mainly responsible for aflatoxin B1 adsorption, even the natural zeolite - clinoptilite has much higher cation exchange capacity (the content of inorganic exchangeable cations) compared to the concentrate of montmorillonite, adsorption of aflatoxin B1 by this mineral is much lower. Comparing the molecular dimensions of aflatoxin B1 molecule with the dimension of channels of clinoptilolite and interlamellar space of montmorillonite it is obvious that this toxin is adsorbed only at the external surface of clinoptilolite while in the montmorillonite all active sites are equally available for its adsorption. Thus, the concentrate of montmorillonite posess by higher adsorption capacity for aflatoxin B1. Results presented in this paper confirmed the fact the differences in the structure of minerals led to their different efficiency for adsorption of aflatoxin B1. Mineralogical and chemical composition, determination of cation exchange capacity, etc., are very important parameters influencing the effectiveness of minerals as aflatoxin B1 adsorbents. [Projekat Ministarstva nauke Republike Srbije, br. 451-03-2802-IP Tip1/142, br. 172018 i br. 34013] <br><br><font color="red"><b> This article has been corrected. Link to the correction <u><a href="http://dx.doi.org/10.2298/HEMIND170208003E">10.2298/HEMIND170208003E</a><u></b></font>

scholarly journals Top-Down Synthesis of NaP Zeolite from Natural Zeolite for the Higher Removal Efficiency of Cs, Sr, and Ni

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 252
Author(s):  
Seokju Hong ◽  
Wooyong Um
Keyword(s):  
Cation Exchange ◽  
Removal Efficiency ◽  
Natural Zeolite ◽  
Cation Exchange Capacity ◽  
Solid Phase ◽  
Exchange Capacity ◽  
Order Kinetic ◽  
Top Down ◽  
Kinetic Experiment ◽  
Bet Analysis

A solid phase of natural zeolite was transformed to Na-zeolite P (NaP zeolite) by a “top-down approach” hydrothermal reaction using 3 M of NaOH solution in a 96 °C oven. Time-dependent X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), XRF, and scanning electron microscopy (SEM) analysis as well as kinetic, isotherm, and cation exchange capacity experiments were performed to understand the mechanism of mineral transition from natural zeolite to NaP zeolite. The XRD crystal peaks of the natural zeolite decreased (decrystallization phase) first, and then the NaP zeolite XRD crystal peaks increased gradually (recrystallization phase). From the XRF results, the dissolution rate of Si was slow in the recrystallization phase, while it was rapid in the decrystallization phase. The specific surface area measured by BET analysis was higher in NaP zeolite (95.95 m2/g) compared to that of natural zeolite (31.35 m2/g). Furthermore, pore structure analysis confirmed that NaP zeolites have more micropores than natural zeolite. In the kinetic experiment, the results showed that the natural zeolite and NaP zeolite were well matched with a pseudo-second-order kinetic model, and reached equilibrium within 24 h. The isotherm experiment results confirmed that both zeolites were well matched with the Langmuir isotherm, and the maximum removal capacity (Qmax) values of Sr and Ni were highly increased in NaP zeolite. In addition, the cation exchange capacity (CEC) experiment showed that NaP zeolite has an enhanced CEC of 310.89 cmol/kg compared to natural zeolite (CEC = 119.19 cmol/kg). In the actual batch sorption test, NaP zeolite (35.3 mg/g) still showed high Cs removal efficiency though it was slightly lower than the natural zeolite (39.0 mg/g). However, in case of Sr and Ni, NaP zeolite (27.9 and 27.8 mg/g, respectively) showed a much higher removal efficiency than natural zeolite (4.9 and 5.5 mg/g for Sr and Ni, respectively). This suggests that NaP zeolite, synthesized by a top-down desilication method, is more practical to remove mixed radionuclides from a waste solution.

scholarly journals Effects of Tree Forest Plantations on Soil Physicochemical Properties in the Arboretumof Ruhande,Southern Province of Rwanda

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Nsengimana Venuste
Keyword(s):  
Organic Carbon ◽  
Physicochemical Properties ◽  
Cation Exchange ◽  
Bulk Density ◽  
Soil Ph ◽  
Tree Species ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Available Phosphorus ◽  
Soil Physicochemical Properties

Different tree speciesare blamed to have negative effects on soil ecosystems by changing soil physicochemical properties, and hence soil quality. However, few researches to verify this statement were done in Rwanda. This study provides prior information on the effects of planted forest tree species on soil physicochemical properties. It was conducted in the Arboretum of Ruhande, in southern Rwanda. Soil cores were collected in plots of exotic, native and agroforestry tree species. Collected soils were analysed for soil pH, total nitrogen, organic carbon, available phosphorus,  aggregate stability, bulk density, soil humidity, cation exchange capacity, and soil texture. Soils sampled under exotic tree species were acidic, richin soil organic carbon, and in soil available phosphorus. Native and agroforestry tree species offer better conditions in soil pH, soil water content, cation exchange capacity, clay and silt. Less variations in soil total nitrogen and soil bulk density were found in soils sampled under all studied forest types. Research concluded that studiedtree species have different effects on soil physicochemical parameters. It recommended further studies to generalize these findings. Key words: soil, exotic, native, agroforestry, soil properties

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