The effect of zeolite treatment by acids on sodium adsorption ratio of coal seam gas water
School of Chemical Engineering, The University of Queensland, Brisbane, QLD 4072, Australia.Water Research (Impact Factor: 5.53). 07/2012; 46(16):5247-54. DOI: 10.1016/j.watres.2012.07.006
Many coal seam gas (CSG) waters contain a sodium ion concentration which is too high relative to calcium and magnesium ions for environment acceptance. Natural zeolites can be used as a cheap and effective method to control sodium adsorption ratio (SAR, which is a measure of the relative preponderance of sodium to calcium and magnesium) due to its high cation exchange capacity. In this study, a natural zeolite from Queensland was examined for its potential to treat CSG water to remove sodium ions to lower SAR and reduce the pH value. The results demonstrate that acid activated zeolite at 30%wt solid ratio can reduce the sodium content from 563.0 to 182.7 ppm; the pH from 8.74 to 6.95; and SAR from 70.3 to 18.5. Based on the results of the batch experiments, the sodium adsorption capacity of the acid-treated zeolite is three times greater than that of the untreated zeolite. Both the untreated and acid-treated zeolite samples were characterized using zeta potential, surface characterization, DTA/TG and particle size distribution in order to explain their adsorption behaviours.
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- "It was proposed that this latter approach may provide a superior material in terms of the ability to remove ammonium ions from solution. This latter hypothesis was supported by previous work by Wang et al.which demonstrated that careful treatment of natural zeolite with dilute acids could substantially improve the exchange of sodium ions from coal seam gas water samples. Factors thought to be beneficial included increase in zeolite surface area, enhancement of material porosity, greater dealumination, and a more negative zeta potential. "
ABSTRACT: This paper is concerned with the study of the equilibrium exchange of ammonium ions with two natural zeolite samples sourced in Australia from Castle Mountain Zeolites and Zeolite Australia. A range of sorption models including Langmuir Vageler, Competitive Langmuir, Freundlich, Temkin, Dubinin Astakhov and Brouers–Sotolongo were applied in order to gain an insight as to the exchange process. In contrast to most previous studies, non-linear regression was used in all instances to determine the best fit of the experimental data. Castle Mountain natural zeolite was found to exhibit higher ammonium capacity than Zeolite Australia material when in the freshly received state, and this behavior was related to the greater amount of sodium ions present relative to calcium ions on the zeolite exchange sites. The zeolite capacity for ammonium ions was also found to be dependent on the solution normality, with 35–60% increase in uptake noted when increasing the ammonium concentration from 250 to 1000 mg/L. The optimal fit of the equilibrium data was achieved by the Freundlich expression as confirmed by use of Akaikes Information Criteria. It was emphasized that the bottle-point method chosen influenced the isotherm profile in several ways, and could lead to misleading interpretation of experiments, especially if the constant zeolite mass approach was followed. Pre-treatment of natural zeolite with acid and subsequently sodium hydroxide promoted the uptake of ammonium species by at least 90%. This paper highlighted the factors which should be taken into account when investigating ammonium ion exchange with natural zeolites.
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ABSTRACT: Graphene oxide (GO) nanosheets were grafted to acid-treated natural clinoptilolite-rich zeolite powders followed by a coupling reaction with a diazonium salt (4-carboxybenzenediazoniumtetrafluoroborate) to the GO surface. Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA) revealed successful grafting of GO nanosheets onto the zeolite surface. The application of the adsorbents for the adsorption of rhodamine B from aqueous solutions was then demonstrated. After reaching adsorption equilibrium the maximum adsorption capacities were shown to be 50.25, 55.56 and 67.56mgg(-1) for pristine natural zeolite, GO grafted zeolite (GO-zeolite) and benzene carboxylic acid derivatized GO-zeolite powders, respectively. The adsorption behavior was fitted to a Langmuir isotherm and shown to follow a pseudo-second-order reaction model. Further, a relationship between surface functional groups, pH and adsorption efficiency was established. Results indicate that benzene carboxylic acid derivatized GO-zeolite powders are environmentally favorable adsorbents for the removal of cationic dyes from aqueous solutions.
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ABSTRACT: The present work aims to study the bulk and surface properties of the TiO2/clinoptilolite composite on the crystalline structure, superficial area, bandgap energy, zeta potential, particle size distribution, and chemical composition; in order to analyze the effect of the clinoptilolite proportion in the photocatalytic degradation of pollutants. TiO 2/clinoptilolite composites were prepared by adding different mass proportions of clinoptilolite to a sol-gel bath containing TiCl4 as the titania precursor. Surface charge studies explain the larger sensitivity to composite ratio observed in the photocatalytic degradation of anionic pollutants than in cationic dyes. An optimum TiO2/clinoptilolite ratio of 90/10 was found to be the most efficient in terms of lower tendency to agglomeration, largest surface area, and increased crystallite size. Improvement in composite surface area occurs only at low clinoptilolite wt% and seems to be caused by lower agglomeration of nanometric TiO2 and acid-induced porosity in the zeolite.
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