Equilibrium and column studies of iron exchange with strong acid cation resin

Abstract

A B S T R A C TThe exchange of iron species from iron(III) chloride solutions with a strong acid cation resin has been investigated in relation to a variety of water and wastewater applications. A detailed equilibrium isotherm analysis was conducted wherein models such as Langmuir-Vageler, Competitive Langmuir, Freundlich, Temkin, Dubinin-Astakhov, Sips and Brouers-Sotolongo were applied to the experimental data. An important conclusion was that both the bottle-point method chosen and solution normality used to generate the ion exchange equilibrium isotherm influenced which sorption model fitted the isotherm profiles optimally. Invariably, the calculated value for the maximum loading of iron on strong acid cation resin was substantially higher than the value of 47.1 g/kg of resin which would occur if one Fe 3 + ion exchanged for three "H + " sites on the resin surface. Consequently, it was suggested that above pH 1, various iron complexes sorbed to the resin in a manner which required less than 3 sites per iron moiety. Column trials suggested that the iron loading was 86.6 g/kg of resin when 1342 mg/L Fe(III) ions in water were flowed at 31.7 BV/h. Regeneration with 5-10% HCl solutions reclaimed approximately 90% of exchange sites.2014 Elsevier Ltd. All rights reserved. IntroductionMetal pollution of our water resources remains a major concern [1-3]. Several methods have been employed to remediate contaminated solutions including precipitation [4], coagulationflocculation [5], adsorption [6-8], ion exchange [9,10], membrane filtration [11], flotation [12,13] and electrochemical means [14]. Physico-chemical techniques are attractive due to a variety of reasons such as process economics, reliability and ease of use [15]. Ion exchange is of particular interest as not only can the metals potentially be recovered but also the technology is well developed, simple and effective [16]. Iron is a common contaminant in natural waters [17], mining effluents [18], hydrometallurgical solutions [19] and a range of other industrial wastes [20]. Demineralization of water and wastewater solutions is widely practiced in industry, usually with a combination of cation and anion resins to remove the dissolved ions [21]. Kaya et al. [22] have shown that the presence of iron even at low concentration can significantly reduce the operating capacity of synthetic strong acid cation resins. Victor-Ortega Abbreviations: A, Temkin isotherm parameter (L/mmol or L/mg); a s , Sips equilibrium isotherm coefficient; a, exponent which represents the inherent energy heterogeneity of the sorbent surface; AIC, Akaike information criterion; ARE, average relative error; b T , Temkin constant related to the heat of adsorption (J/mol); BV, bed volumes; C e , equilibrium concentration of iron ions in solution (mg/L); C o , initial concentration of iron ions in solution (mg/L); e, adsorption potential (J/mol); E, energy of adsorption (J/mol); eq, equivalents; EABS, sum of the absolute errors; HYBRID, hybrid fractional error function; K CL , Competitive Lan...

Ion Exchange to Capture Iron after Real Effluent Treatment by Fenton’s Process

“…On the other hand, by increasing the initial pH, there will be lower IE removal efficiencies due to the precipitation of metallic hydroxides as the dominant mechanism and, consequently, lower cation exchange capacity. The pH effect was a parameter widely studied by other authors [31,32], who corroborated the benefit of a low pH in equilibrium isotherms. For a correct assessment in terms of COD and dissolved iron removal, in this work the Fenton reaction was stopped, using a NaOH solution to increase the pH to 11.…”

Adsorption of nickel(II) on polyacrylonitrile nanofiber modified with 2-(2′-pyridyl)imidazole

“…Acid capacity was calculated from the titration data using Eq. (2) in which N a is the normality of added acid and V a is the added volume of acid. N b is the normality of acid in solution calculated from the measured pH, V b is the batch volume and m PAN-pim is the mass of fiber.…”

“…Separation and recovery of valuable and/or harmful metals from metals processing streams is a challenge because of the complexity of the systems. Ion-exchange and adsorption are well established, safe, and environmentally benign methods for purification of effluents and process waters as well as for recovery of by-products and manufacturing of metal chemicals [1][2][3]. Large-scale ion exchange and adsorption processes are usually carried out using fixed-bed separation systems, in which a compromise between separation efficiency and throughput has to be made.…”

Preparation of high purity PCC from medium- and low-grade limestones using the strongly acidic cation exchange resin

“…Trilite SCR-B was used for synthesizing Ca(OH) 2 and CaCO 3 . In the ionic form of SCR, H + was substituted for Na + using HCl (35%) (1:1 kg:kg) [16,17, [21][22][23][24][25][26].…”

“…SCR, able to remove Ca 2+ and Mg 2+ , is a suitable ion exchange resin for water treatment such as softening of hard water and manufacture of pure water. Based on the physical and chemical properties of SCR, Ca(OH) 2 and CaCO 3 were synthesized using reaction with SCR after dissociative reaction of CaO prepared from medium-and low-grade limes [17, [21][22][23][24][25][26].…”