Bibliografie Adsorption von Schwermetallen an Zeolithe

Diese Leseliste zum Thema "Adsorption von Schwermetallen an Zeolithe" wurde im Februar 2005 erstellt und gibt einen kurzen Einstieg in die Literatur.

Abadzic, S. D. and J. N. Ryan (2001). "Particle release and permeability reduction in a natural zeolite (clinoptilolite) and sand porous medium." Environ Sci Technol 35(22): 4502-8.

To evaluate clinoptilolite, a natural zeolite, as a candidate material for a permeable reactive barrier for removal of strontium from groundwater, we investigated particle release and permeability reduction in clinoptilolite and sand porous media. In flow-through column experiments, we tested the effects of solution chemistry, grain size, and clinoptilolite pretreatment on particle release and hydraulic conductivity. Permeability reduction occurred not in the clinoptilolite itself but only in finer-grained sand down-gradient of the clinoptilolite. Solutions of high ionic strength inhibited particle release and prevented clogging. Clinoptilolite of larger grain size produced slightly less particle release and clogging. Two pretreatments of the clinoptilolite, rinsing to remove fine particles and calcining to improve strength, reduced particle release and clogging. Calcining, however, significantly reduced the strontium binding strength of the clinoptilolite.

Payne, K. B. and T. M. Abdel-Fattah (2004). "Adsorption of divalent lead ions by zeolites and activated carbon: effects of pH, temperature, and ionic strength." J Environ Sci Health A Tox Hazard Subst Environ Eng 39(9): 2275-91.

Lead alloy bullets used at the 2600 military small arm ranges and 9000 nonmilitary outdoor shooting ranges in the United States are a source of mobilized lead ions under conditions of low pH, significant changes in ionic strength, changes in the reduction oxidation potential (redox), and through binding metal ions to soil organic matter. Once mobile, these lead ions can contaminate adjacent soil and water. Batch adsorption kinetic and isotherm studies were conducted to compare and evaluate different types of adsorbents for lead ion removal from aqueous media. The effects on lead ion absorption from pH changes, competing ions, and temperature increases were also investigated. Adsorbent materials such as activated carbon and naturally occurring zeolites (clinoptilolite and chabazite) were selected because of their relative low cost and because the zeolites are potential point-of-use materials for mitigating wastewater runoff. Molecular sieves, Faujasite (13X) and Linde type A (5A) were selected because they provide a basis for comparison with previous studies and represent well-characterized materials. The relative rate for lead ion adsorption was: 13X > chabazite > clinoptilolite > 5A > activated carbon. Modeling lead ion adsorption by these adsorbents using the Langmuir and Freundlich isotherm expressions determined the adsorbents' capacity for lead ion removal from aqueous media. 13X, 5A, and activated carbon best fit the Langmuir isotherm expression; chabazite and clinoptilolite best fit the Freundlich isotherm. Applications of chabazite would require pH values between 4 and 11, clinoptilolite between 3 and 11, while activated carbon would operate at a pH above 7. Ionic competition reduced lead ion removal by the zeolites, but enhanced activated carbon performance. Increasing temperature improved adsorption performance for the zeolites; activated carbon lead ion adsorption was temperature independent.

Bolan, N. S., L. Wong, et al. (2004). "Nutrient removal from farm effluents." Bioresour Technol 94(3): 251-60.

The objectives of the study were: (i) to examine the efficiency of nutrient removal during the treatment of dairy farm effluent in a two-pond system, and (ii) to produce an inexpensive but effective nutrient trap which could be recycled as a nutrient source or soil mulch. The concentration of chemical oxygen demand (COD), biological oxygen demand (BOD), nitrogen (N), phosphorus (P) and potassium (K) in a two-pond system used to treat dairy farm effluent was monitored over a period of 7 months. The retention of nutrients by two porous materials was examined both in the laboratory batch (zeolite and bark) and pilot-scale field (bark) experiments. The results indicated that biological treatment of farm effluents using the two-pond system was not effective in the removal of nutrients, which are likely to become pollutant when discharged to waterways. Both the bark and zeolite materials were effective in the removal of N, P and K from effluent. These materials can be placed in the second (i.e., aerobic) pond to treat effluents, which can then be discharged to streams with minimum impact on water quality. The nutrient-enriched porous materials can be recycled as a source of nutrients and soil conditioner.

el-Bishtawi, R. F. and A. A. Ali (2001). "Sorption kinetics of lead ions by zeolite tuff." J Environ Sci Health A Tox Hazard Subst Environ Eng 36(6): 1055-72.

The kinetics of sorption of Pb ions by zeolite tuff treated with NaCl solution was studied using agitated batch laboratory apparatus. The uptake of ions was determined as a function of time at different values of initial Pb ion concentration, zeolite particle size, slurry concentration, solution temperature and pH. The pseudo-second order reaction model was successfully applied to the experimental data with correlation coefficients higher than 0.98. Sorption rates decreased with increase in average particle diameter while it increased with increase in each of the initial Pb ion concentration, slurry concentration, solution temperature and solution pH. Results indicate the importance of chemisorption.

Tillman, F. D., Jr., S. L. Bartelt-Hunt, et al. (2004). "Evaluation of an organoclay, an organoclay-anthracite blend, clinoptilolite, and hydroxy-apatite as sorbents for heavy metal removal from water." Bull Environ Contam Toxicol 72(6): 1134-41.

Vaca Mier, M., R. Lopez Callejas, et al. (2001). "Heavy metal removal with Mexican clinoptilolite: multi-component ionic exchange." Water Res 35(2): 373-8.

This paper describes the interactions of Pb(II), Cd(II), and Cr(VI) competing for ion-exchange sites in naturally occurring clinoptilolite. Dissolved Pb and Cd were effectively removed within 18 h in batch reactors, with higher removal efficiencies (> 95%) in the acidic pH range. The presence of Cr(VI), which can interact with these metals to form anionic complexes, significantly diminished the Pb and Cd removal efficiencies. A decrease in the efficiency of clinoptilolite to remove Pb was also observed in the high (> or = 10) pH range. This was attributed to the formation of anionic hydroxo-complexes with little affinity for cationic ion exchange sites. Pb outcompeted Cd for ion exchange sites in a flow-through column packed with clinoptilolite (contact time = 10 s). The preferential removal of Pb in column, but not in batch reactors, reflects that competitive retention can be affected by contact time because diffusion kinetics may influence the removal efficiency to a greater extent than equilibrium partitioning. Phenol, which was tested as a representative organic co-contaminant, slightly hindered heavy metal removal in batch reactors. This was attributed to the formation of organometallic complexes that cannot penetrate the zeolite exchange channels. Altogether, these results show that natural zeolites hold great potential to remove cationic heavy metal species from industrial wastewater. Nevertheless, process efficiency can be hindered by the presence of ligands that form complexes with reduced accessibility and/or affinity for ion exchange.

Alvarez-Ayuso, E., A. Garcia-Sanchez, et al. (2003). "Purification of metal electroplating waste waters using zeolites." Water Res 37(20): 4855-62.

The sorption behaviour of natural (clinoptilolite) and synthetic (NaP1) zeolites has been studied with respect to Cr(III), Ni(II), Zn(II), Cu(II) and Cd(II) in order to consider its application to purify metal finishing waste waters. The batch method has been employed using metal concentrations in solution ranged from 10 to 200 mg/l and solid/liquid ratios ranged from 2.5 to 10 g/l. The Langmuir model was found to describe well all sorption processes, allowing to establish metal sorption sequences from which the main retention mechanism involved for each metal has been inferred. Synthetic zeolite exhibited about 10 times greater sorption capacities (b(Cr)=0.838 mmol/g, b(Ni)=0.342 mmol/g, b(Zn)=0.499 mmol/g, b(Cu)=0.795 mmol/g, b(Cd)=0.452 mmol/g) than natural zeolite (b(Cr)=0.079 mmol/g, b(Ni)=0.034 mmol/g, b(Zn)=0.053 mmol/g, b(Cu)=0.093 mmol/g, b(Cd)=0.041 mmol/g), appearing, therefore, as most suitable to perform metal waste water purification processes. This mineral showed the same high sorption capacity values when used in the purification of metal electroplating waste waters.

An, H. K., B. Y. Park, et al. (2001). "Crab shell for the removal of heavy metals from aqueous solution." Water Res 35(15): 3551-6.

The ability of crab shell to remove heavy metals from aqueous solution was evaluated by comparing with that of several sorbents (cation exchange resin, zeolite, granular activated carbon, powdered activated carbon). All experiments were conducted using several heavy metal ion solutions (Pb, Cd, Cu, Cr). The orders of heavy metal removal capacity and initial heavy metal removal rate were found as crab shell > cation exchange resin > zeolite > powdered activated carbon>granular activated carbon. Therefore, crab shell is satisfactory as a good biosorbent for the heavy metal removal. The study indicates that the removal of these heavy metals is selective, with Pb and Cr being removed in preference to Cd and Cu. The sorption equilibrium of heavy metal ions on sorbents was modeled on the applications of Langmuir and Freundlich.

Eventov, V. L., M. Andrianova, et al. (1999). "[Water purification for hemodialysis]." Med Tekh(2): 21-5.

An electrodialysis system has been designed to purify water. It comprises two units: a preliminary preparation unit and an electrodialysis one. The system consists of columns containing zeolite, activated carbon, and ion-exchange resins. Zeolite makes water free from mechanical impurities and iron, activated carbon adsorbs organic matter and chlorine ions, ion-exchange resins soften water. The electrodialysis unit is noted for its original design. Mathematical simulation has allowed the authors to optimize the design and to make a block that makes the process continuous without repolarization, which can decant the minimum levels of salt concentrates, thus decreasing energy supply to 2 W per liter. The unit is made as a pressure filter design having the platinum-titanium electrodes and membranes MK-40 and MK-45 made in Russia. The system operates automatically. Its all components are made in Russia.

Minamisawa, H., S. Iizima, et al. (2004). "Preconcentration of gallium by coprecipitation with synthetic zeolites prior to determination by electrothermal atomic absorption spectrometry." Anal Sci 20(4): 683-7.

Synthetic zeolites were dissolved in nitric acid, and the resulting solution used as a coprecipitant for the preconcentration of trace amounts of gallium in water samples prior to determination by electrothermal atomic absorption spectrometry (ETAAS). The gallium preconcentration conditions and the ETAAS measurement conditions were optimized. Gallium was quantitatively concentrated with the zeolites coprecipitate from pH 6.0 to 8.0. The coprecipitate was easily dissolved in nitric acid, and an aliquot of the resulting solution was introduced directly into a tungsten metal furnace. The atomic absorbance of gallium in the resulting solution was measured by ETAAS. An ashing temperature of 400 degrees C and an atomizing temperature of 2600 degrees C were selected. The calibration curve was linear up to 3.0 microg of gallium and passed through the origin. The detection limit (S/N > or = 3) for gallium was 0.08 microg/100 cm3. The relative standard deviation at 1.0 microg/100 cm3 was 3.0% (n = 5). The proposed method has been successfully applied to trace gallium analysis in environmental water samples.

Garcia Hernandez, J. E., M. M. Gonzalez Martin, et al. (1992). "Treatment of wastewater effluents with Phillipsite-rich tuffs." Environ Pollut 76(3): 219-23.

The presence of abundant zeolites in association with volcanic pumiceous materials in Tererife (Canary Islands) prompted us to study their properties as a water purifying bed for inorganic contaminants, pathogenic bacteria, and soluble organic matter. The experimental model used was a chemical percolation reactor with a constant flux of solution, where the fixation kinetics were studied by comparing the input and the output solutions. The ammonium and phosphate retention values found after 10 days of constant percolation were 70% and 14%, respectively. In addition, a high reduction of soluble organic matter was observed, as well as the total removal of the bacteria species studied. The N-P-K values of the soluble and exchangeable nutrients indicate the potential capacity of the bed as a slow-release fertilizer.

Ozturk, H. S., S. S. Ok, et al. (2004). "Leaching of boron through sewage sludge amended soil: the role of clinoptilolite." Bioresour Technol 95(1): 11-4.

A laboratory experiment was conducted to determine the release of boron from soil-sewage sludge mixtures by leaching using a clinoptilolite type natural zeolite, before land application of the sewage sludge. Soil columns were filled up with the clinoptilolite soil after mixing with sewage sludge at a rate of 30 tons ha(-1) and with two different particle sizes (0.1-0.25 and 1.0-2.0 mm) of clinoptilolite each at the concentrations of 1% and 2%. The particle size and the application rate of clinoptilolite affected both boron leaching from soil compared to the control treatment (soil and sewage sludge mixture). The total soluble boron leached from a soil column varied from 66-92% depending on the applications of clinoptilolite and reached 96% for the control treatment, following application of 80 cm depth of water in all treatments. In the cases of the 1% application rate of 0.1-0.25 and 1-2 mm sized clinoptilolite 78% and 92% of the total boron leached, respectively. While at 2% application rate of 0.1-0.25 and 1-2 mm zeolite, 66% and 87% of total soluble boron leached, respectively. Boron concentrations in the soil layers increased as application rate increased and particle size of clinoptilolite decreased because of its high adsorption capacity. Adsorption isotherms indicated that clinoptilolite had a high adsorption capacity for boron compared to the sewage sludge and soil.

Moreno, N., X. Querol, et al. (2001). "Utilization of zeolites synthesized from coal fly ash for the purification of acid mine waters." Environ Sci Technol 35(17): 3526-34.

Two pilot plant products containing 65 and 45% NaP1 zeolite were obtained from two Spanish coal fly ashes (Narcea and Teruel Power Station, respectively). The zeolitic product obtained showed a cation exchange capacity (CEC) of 2.7 and 2.0 mequiv/g, respectively. Decontamination tests of three acid mine waters from southwestern Spain were carried out using the zeolite derived from fly ash and commercial synthetic zeolite. The results demonstrate that the zeolitic material could be employed for heavy metal uptake in the water purification process. Doses of 5-30 g of zeolite/L have been applied according on the zeolite species and the heavy metal levels. Moreover, the application of zeolites increases the pH. This causes metal-bearing solid phases to precipitate and enhances the efficiency of the decontamination process.

Babel, S. and T. A. Kurniawan (2003). "Low-cost adsorbents for heavy metals uptake from contaminated water: a review." J Hazard Mater 97(1-3): 219-43.

In this article, the technical feasibility of various low-cost adsorbents for heavy metal removal from contaminated water has been reviewed. Instead of using commercial activated carbon, researchers have worked on inexpensive materials, such as chitosan, zeolites, and other adsorbents, which have high adsorption capacity and are locally available. The results of their removal performance are compared to that of activated carbon and are presented in this study. It is evident from our literature survey of about 100 papers that low-cost adsorbents have demonstrated outstanding removal capabilities for certain metal ions as compared to activated carbon. Adsorbents that stand out for high adsorption capacities are chitosan (815, 273, 250 mg/g of Hg(2+), Cr(6+), and Cd(2+), respectively), zeolites (175 and 137 mg/g of Pb(2+) and Cd(2+), respectively), waste slurry (1030, 560, 540 mg/g of Pb(2+), Hg(2+), and Cr(6+), respectively), and lignin (1865 mg/g of Pb(2+)). These adsorbents are suitable for inorganic effluent treatment containing the metal ions mentioned previously. It is important to note that the adsorption capacities of the adsorbents presented in this paper vary, depending on the characteristics of the individual adsorbent, the extent of chemical modifications, and the concentration of adsorbate.

Barbosa, L. A., R. A. van Santen, et al. (2001). "Stability of Zn(II) cations in chabazite studied by periodical density functional theory." J Am Chem Soc 123(19): 4530-40.

The location of the Zn(2+) cation in Zn-exchanged chabazite has been studied by the periodical density functional method. Chabazite was chosen as a zeolite model, because it contains three different types of rings commonly found in the zeolite structures: four-, six-, and eight-membered rings. Two aluminum atoms have been employed to substitute the silicon atoms in the same D6R unit cell of the zeolite framework. This leads to different arrangements for the Bronsted site pair and the Zn(II) cation. The two Bronsted sites are found to be more stable when placed in the small ring (4T ring) than in the other rings. This suggests that the most reactive Bronsted sites are located in the large rings. Two Bronsted sites are most stable when the O(H)-Al-O-Si-O(H)-Al sequence is followed in the same ring instead of being located in two different rings. This resembles the aluminum distribution in the small four-membered ring and agrees with bond order conservation rules. The cation stability is markedly influenced by the distortions of the framework. Other factors that also contribute to the stabilization are the aluminum content near the cation and the stability of the original Bronsted sites. The Zn(2+) cation is more stable in the large rings than in the small ones, the six-membered one being the most stable configuration. In the small rings, the cation is, therefore, more reactive. Two different probe molecules have been used to study the interaction with the Zn(II) cation: water and methane. These probe molecules can extract the active center from its original position. For the water molecule, this effect is large and leads to a high framework relaxation. The value of the binding energy of this molecule to the active sites is influenced by these framework relaxations as well as by the cationic position environment. For weakly interacting methane, these effects are significantly less.

Simpson, S. L., I. D. Pryor, et al. (2002). "Considerations for capping metal-contaminated sediments in dynamic estuarine environments." Environ Sci Technol 36(17): 3772-8.

The effects of tides, bioturbating organisms, and periods of anoxia on metal fluxes from contaminated harbor sediments in a shallow tidal estuarine bay were studied, together with capping technology options for the containment of metal contaminants. Zinc fluxes from the sediments were high, ranging from 10 to 89 mg of Zn m(-2) day(-1). In the absence of capping, experiments in corer-reactors showed that simulated tidal processes increased zinc fluxes 5-fold. Fluxes were also greater in the presence of sediment-dwelling organisms. If organisms were removed, and recolonizing organisms later added, their bioturbation activities initially lowered zinc fluxes, but fluxes gradually reached steady state at the higher levels seen previously. Capping materials physically isolate contaminated sediments, provide a binding substrate for metals released from the sediment and importantly create an anoxic environment below the cap, which stimulates the formation of insoluble metal sulfides. Clean sediment (5 mm) was the most effective capping material in reducing zinc fluxes. Zeolite/sand mixtures (10 mm) also greatly reduced these fluxes, but significant breakthrough of zinc occurred after 2 weeks. Sand (20 mm) was not effective. The presence of organisms disturbed capping materials and increased zinc fluxes. Installed capping materials should have depths of >30 cm to minimize organisms burrowing to contaminated sediments beneath.

Matis, K. A., A. I. Zouboulis, et al. (2004). "Application of flotation for the separation of metal-loaded zeolites." Chemosphere 55(1): 65-72.

Several industrial wastewater streams may contain heavy metal ions, which must be effectively removed, before the discharge or reuse of treated waters could take place. Different bonding materials, presenting selectivity and fast reaction kinetics for the removal of metals, have been examined for this purpose. The objective of the present paper was to investigate the application of dispersed-air flotation for the separation of metal-loaded sorbents. Two similar zeolite samples were applied as effective bonding agents for the removal of zinc, a toxic metal commonly found in many industrial wastewaters. This combined process, termed sorptive flotation, involves the preliminary scavenging of metal ions, by using the appropriate sorbent particles (usually present as ultrafine particulates), followed by flotation for the effective separation of them. The obtained results were very promising, as both metal and sorbent were effectively removed/separated from the dispersion.

Sublet, R., M. O. Simonnot, et al. (2003). "Selection of an adsorbent for lead removal from drinking water by a point-of-use treatment device." Water Res 37(20): 4904-12.

The removal of lead from drinking water was investigated to develop a point-of-use water filter that could meet the regulation imposed by the new European Directive 98-83 lowering lead concentration in drinking water below 10 microgL(-1). The objective of this research was to assess the potential of different adsorbents (zeolites, resins, activated carbon, manganese oxides, cellulose powder) to remove lead from tap water with a very short contact time. To begin, the repartition of the lead species in a tap water and a mineral water was computed with the computer model CHESS. It showed that in bicarbonated waters lead is mainly under lead carbonate form, either in the aqueous or in the mineral phase. Batch experiments were then conducted to measure the equilibrium adsorption isotherms of the adsorbents. Then, for five of them, dynamic experiments in micro-columns were carried out to assess the outlet lead concentration level. Three adsorbents gave rise to a leakage concentration lower than 10 microgL(-1) and were then selected for prototypes experiments: chabasite, an activated carbon coated with a synthetic zeolite and a natural manganese oxide. The proposed method clearly showed that the measurement of equilibrium isotherms is not sufficient to predict the effectiveness of an adsorbent, and must be coupled with dynamic experiments.

Bosso, S. T. and J. Enzweiler (2002). "Evaluation of heavy metal removal from aqueous solution onto scolecite." Water Res 36(19): 4795-800.

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