Ion Exchange Capacity Of Zeolite Research Articles

Long-term investigations on ammonium removal with zeolite in compact vertical flow treatment wetlands under field conditions.

The scope of this study was to investigate if using zeolite as a reactive material in a vertical-flow wetland under field conditions improves ammonium removal from domestic wastewater in the long term. The experimental setup consisted of two pilot-scale first stage French vertical flow treatment wetlands (2.3 m2 surface area each), which were implemented under field scale conditions inside a wastewater treatment plant in the central region of France (L'Encloitre, 37360). The filters were operated during 27 months. A compact pilot containing Leca® as a main filtration layer (Ø 1-5 mm) was compared to a similar one filled with natural zeolite (Ø 2-5 mm). The pilots were fed according to regular feeding/resting periods (3½/7 days) and the nominal loading rate was of 300 g COD m-2 d-1 and 33 g·N·m-2·d-1 during operation. In both pilots, results showed a removal efficiency of more than 90 and 85% for TSS and COD, respectively. They also showed an increased NH4-N removal of 9% on average (total removal efficiency of 84%) with the use of zeolite compared to Leca®. The ion exchange capacity of zeolite seemed not to be affected after 27 months of experiments; however, the material was compacted and more friable after operation.

Ion exchange capacity of zeolite A with zinc nitrate and its antimicrobial activity

Abstract Various type of zeolites has been produced based on kaolinite and this study likewise utilized kaolin clay as raw material to synthesis zeolite A. Kaolin was in inactive state, therefore it was transformed to metakaolin through dehydroxylation at 800 °C for 4 h. The metakaolin as a source of silica and alumina was then utilized in the synthesis of zeolite A. After hydrothermal synthesis, the zeolite A was exchanged with different concentration of zinc nitrate solution. Zinc content in ion-exchanged zeolite A, ZnA was determined through AAS to calculate the ion exchange capacity. Higher concentration of zinc nitrate had higher zinc content and higher ion exchange capacity. Zeolite A and zinc-exchanged zeolite A were characterized under SEM, XRD and FTIR. Finally, zeolite A and zinc-exchanged zeolite A was used to investigate the antimicrobial properties against gram-negative bacteria, Escherichia coli and gram-positive bacteria Staphylococcus aureus. There was no antimicrobial activity for zeolite A yet zinc-ion–exchanged zeolite A showed inhibition zones around the samples for both the microorganisms.

One-Step Hydrothermal Synthesis of Zeolite X Powder from Natural Low-Grade Diatomite.

Zeolite X powder was synthesized using natural low-grade diatomite as the main source of Si but only as a partial source of Al via a simple and green hydrothermal method. The microstructure and surface properties of the obtained samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), wavelength dispersive X-ray fluorescence (XRF), calcium ion exchange capacity (CEC), thermogravimetric-differential thermal (TG-DTA) analysis, and N2 adsorption-desorption technique. The influence of various synthesis factors, including aging time and temperature, crystallization time and temperature, Na2O/SiO2 and H2O/Na2O ratio on the CEC of zeolite, were systematically investigated. The as-synthesized zeolite X with binary meso-microporous structure possessed remarkable thermal stability, high calcium ion exchange capacity of 248 mg/g and large surface area of 453 m2/g. In addition, the calcium ion exchange capacity of zeolite X was found to be mainly determined by the crystallization degree. In conclusion, the synthesized zeolite X using diatomite as a cost-effective raw material in this study has great potential for industrial application such as catalyst support and adsorbent.

Effects of zeolite application on nitrate and ammonium retention of a loamy soil under saturated conditions

Nitrogen (N) loss from irrigated cropland, especially in rice paddies, results in low N-use efficiency and groundwater contamination. Soil conditions that increase ammonium and nitrate ion retention alleviate these problems. Clinoptilolite, a naturally occurring zeolite with high-exchange capacity, may be used to absorb ammonium and retard excess leaching of nitrate. The objectives of this research were to determine the effects of different rates of Ca–K-zeolite application (0, 2, 4, and 8 g/kg soil) on pore water velocity and leaching of ammonium and nitrate applied as ammonium nitrate fertiliser to a loam soil at a rate of 350 kg N/ha under saturated conditions similar to that of a rice paddy. The results indicate that Ca–K-zeolite applications of 4 and 8 g/kg soil increase the pore water velocity by 35% and 74%, respectively. The maximum relative concentration (c/co) for the nitrate breakthrough curve occurring at pore volume of about 0.5 was reduced by 15% with a zeolite application rate of 8 g/kg soil. When applying 40 cm of leaching water, leached nitrate was 75% and 63% of total applied nitrate at the soil surface with zeolite applications of 4 and 8 g/kg soil, respectively. Due to the high ion exchange capacity of zeolite, the application of zeolite at 2 g/kg soil is enough to increase the exchange sites in the soil in order to absorb the applied ammonium and prevent its leaching by the inflow water. The maximum ammonium concentration in the breakthrough curve for the zeolite application rate of 2 g/kg soil was reduced by 43% compared with the control treatment. The relationship between the hydrodynamic dispersion coefficient (D) for nitrate and pore water velocity (v) was not linear and it was correlated with squared pore water velocity. The coefficient of the relationship between D and v2 was dependent on the zeolite application rate and linearly increased with this rate.

A comparative study of ion exchange kinetics in zinc/lead—modified zeolite-clinoptilolite systems

The kinetics of zinc and lead ions removal by modified zeolite-clinoptilolite has been investigated. The rate of the ion exchange process for lead ions is faster than for zinc ions, as well as the time needed to reach the equilibrium. The ion exchange capacity of zeolite of lead ions is doubly higher than that of zinc ions. Diffusion models according to the Vermeulen's approximation, the parabolic diffusion model and the homogeneous diffusion model have been tested with the experimental data of ion exchange for zinc and lead. For both systems examined, the best fit of the models proposed with the experimental data was shown by the Vermeulen's approximation and the homogeneous diffusion model with t → t ∞. The diffusion coefficients are calculated from kinetic models of lead ions they are of the order of 10 −6 cm 2/min, constant for all examined initial concentrations and not dependent on time. The diffusion coefficients in the system of zinc ions is of the order of 10 −8 cm 2/min, also independent of initial concentrations, but decreasing with time from the beginning of ion exchange to the equilibrium.

Investigation of ammonia removal from polluted waters by Clinoptilolite zeolite

Ammonia nitrogen compounds in the wastewaters and effluents have harmful effects on water resources. Ion exchange with zeolites is a separation process for ammonia removal from effluents. The objective of this research was to study the efficiency of an ammonia removal and the factor affecting to this process. The Clinoptilolite was obtained from Semnan mines at the north part of Iran. The samples were grounded and sieved based on the U.S. standard mesh number 20, 30, 40 and conditioned by ammonia sulfate and sodium chloride solutions. The characteristics of samples for ammonia removal and the selectivity sequence for adsorbing interfering cations were then determined. Results shown that the average ion exchange capacity of zeolite in batch and continuous systems were 6.65–16 and 16.31–19.5 mg NH4 + /g zeolite weight, respectively. In study on the zeolite for selective cations showed the ranking of K+, NH4 +, Na+, Ca2+ and Mg2+ respectively. Results indicated that high level of regeneration (95–98%) might be achieved with NaCl solution. Based on the results, Clinoptilolite may be effective applied in wastewater treatment, both from technical and economical aspects.