Behaviour of natural zeolites used for the treatment of simulated and actual coal seam gas water

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• 作者：Graeme J. Millar ; ^{graeme.millar@qut.edu.au" class="auth_mail" title="E-mail the corresponding author} ; Sara J. Couperthwaite ; Kemal Alyuz
• 关键词：α ; Hill coefficient ; ARE ; average relative error ; C ; intercept (g/kg) ; CSG ; coal seam gas ; C0 ; initial concentration of sodium ions in solution (mmol/L or mg/L) ; Ce ; sodium ion concentration in solution at equilibrium (mmol/L or mg/L) ; E ; the energy of adsorption (J/mol) ; ε ; adsorption potential (J/mol) ; EABS ; sum of the absolute errors ; HYBRID ; hybrid fractional error function ; KF ; Freundlich coefficient (mg1&minus ; 1/n L1/n g&minus ; 1 or mmol1-1/n L1/n mol-1) ; KLV ; the &ldquo ; half value&rdquo
• 刊名：Journal of Environmental Chemical Engineering
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：4
• 期：2
• 页码：1918-1928
• 全文大小：1924 K

文摘

Coal seam gas operations produce significant quantities of associated water which often require demineralization. Ion exchange with natural zeolites has been proposed as a possible approach. The interaction of natural zeolites with solutions of sodium chloride and sodium bicarbonate in addition to coal seam gas water is not clear. Hence, we investigated ion exchange kinetics, equilibrium, and column behaviour of an Australian natural zeolite. Kinetic tests suggested that the pseudo first order equation best simulated the data. Intraparticle diffusion was part of the rate limiting step and more than one diffusion process controlled the overall rate of sodium ion uptake. Using a constant mass of zeolite and variable concentration of either sodium chloride or sodium bicarbonate resulted in a convex isotherm which was fitted by a Langmuir model. However, using a variable mass of zeolite and constant concentration of sodium ions revealed that the exchange of sodium ions with the zeolite surface sites was in fact unfavourable. Sodium ion exchange from bicarbonate solutions (10.3 g Na/kg zeolite) was preferred relative to exchange from sodium chloride solutions (6.4 g Na/kg zeolite). The formation of calcium carbonate species was proposed to explain the observed behaviour. Column studies of coal seam gas water showed that natural zeolite had limited ability to reduce the concentration of sodium ions (loading 2.1 g Na/kg zeolite) with rapid breakthrough observed. It was concluded that natural zeolites may not be suitable for the removal of cations from coal seam gas water without improvement of their physical properties.