Commercial Ion Exchange Resin Research Articles

Hybrid anion exchanger for trace phosphate removal from water and wastewater

Throughout recent decades, the wastewater treatment industry has identified the discharge of nutrients, including phosphates and nitrates, into waterways as a risk to natural environments due to the serious effects of eutrophication. For this reason, new tertiary treatment processes have abounded; these processes generally utilize physico–chemical and biological methods to remove nutrients from secondary wastewaters. The disadvantages of such methods involve larger reactor volumes, operating costs, and waste sludge production; furthermore, complete nutrient removal is unattainable due to thermodynamic and kinetic limitations. The subject study presents the development and performance of a new phosphate-selective sorbent, referred to as hybrid anion exchanger or HAIX. HAIX combines durability and mechanical strength of polymeric anion exchange resins with high sorption affinity of hydrated ferric oxide (HFO) toward phosphate. HAIX is essentially a polymeric anion exchanger within which HFO nanoparticles have been dispersed irreversibly. Laboratory studies show that HAIX selectively removes phosphate from the background of much higher concentrations of competing sulfate, chloride and bicarbonate anions due to the combined presence of Coulombic and Lewis acid–base interactions. Experimental results demonstrate that HAIX's phosphate–sulfate separation factor is over two orders of magnitude greater than that of currently available commercial ion exchange resins. Additionally, optimal HAIX performance occurs at typical secondary wastewater pH conditions i.e., around 7.5. HAIX is amenable to efficient regeneration and reuse with no noticeable loss in capacity.

Removal of chromium from electroplating industry effluents by ion exchange resins

Effluent discharged from the chromium electroplating industry contains a large number of metals, including chromium, copper, nickel, zinc, manganese and lead. The ion exchange process is an alternative technique for application in the treatment of industrial wastewater containing heavy metals and indeed it has proven to be very promising in the removal and recovery of valuable species. The main objective of the present work is to evaluate the performance of commercial ion exchange resins for removing chromium trivalent from industrial effluents, and for this purpose two resins were tested: a chelating exchange resin (Diaion CR11) and a weak cationic resin (Amberlite IRC86). In order to evaluate the sorption capacity of the resins some equilibrium experiments were carried out, being the temperature and pH the main variables considered. The chromium solutions employed in the experiments were synthetic solutions and industrial effluents. In addition, a transient test was also performed as an attempt to understand the kinetic behaviour of the process.

Purification of dilute hydrofluoric acid by commercial ion exchange resins

This paper describes the results from an experimental study of the purification of dilute hydrofluoric acid (5 wt.%) by ion exchange. Hydrofluoric acid was prepared by dilution from technical grade concentrated HF; important amounts of metal impurities were found in the diluted acid, mainly Na, Fe, As, B, Ca, K, Mg, Mn, Mo, PO 4 3−, and Ti. The semiconductor industry developed the Semiconductor Equipment and Materials International (SEMI) standards to establish the quality requirements for the chemicals used in this sector; one of these standards, SEMI C29 was proposed for 4.9 wt.% HF. Grade 2 HF accounts for impurity levels in the range of 10 ppb. Taking into account this reference, 17 impurities exceed the limits of the standard: Al, As, B, Ca, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Ti, Zn, Zr and PO 4 3−. The purification was performed with two columns containing commercial cation and anion resins from Dow, Bayer and Rohm and Haas companies. Different resin samples were immersed in 5 wt.% HF at different contact times up to 30 days in order to determine any weight change due to chemical attack; no weight losses were detected, however the weight of the two weak anion resins increased more than 20% indicating the interaction between these resins and HF. The metal pollutants were found in both cationic and anionic forms, due to the high concentration of fluoride, and its ability to form cationic and anionic complexes; the speciation of impurities was calculated using the Visual Minteq software. The results from the purification experiments show that 14 of 17 impurities fulfill the requirements of the standard C29, Grade 2. The limits of Al, B, Cu, Li, Mn, Mo, Ni, Ti, Zn and Zr are easily attained, while the concentration of K, Mg and Ca are very close to the limits. As, Fe and PO 4 3− were poorly retained in the resins and their concentrations exceed the limits of Grade 2; more selective resins need to be investigated to reduce the concentration of these impurities in HF matrices. In the case of Na, although removal was higher than 95%, the limit was exceeded due to the high initial concentration.

An exclusion mechanism in ion exchange chromatography

Protein dynamic binding capacities on ion exchange resins are typically expected to decrease with increasing conductivity and decreasing protein charge. There are, however, conditions where capacity increases with increasing conductivity and decreasing protein charge. Capacity measurements on two different commercial ion exchange resins with three different monoclonal antibodies at various pH and conductivities exhibited two domains. In the first domain, the capacity unexpectedly increased with increasing conductivity and decreasing protein charge. The second domain exhibited traditional behavior. A mechanism to explain the first domain is postulated; proteins initially bind to the outer pore regions and electrostatically hinder subsequent protein transport. Such a mechanism is supported by protein capacity and confocal microscopy studies whose results suggest how knowledge of the two types of IEX behavior can be leveraged in optimizing resins and processes.

Esterification of acetic acid with isopropanol coupled with pervaporation

Reaction–pervaporation hybrid processes can be an alternative to classical chemical processes to enhance the conversion of equilibrium-limited reactions such as esterification and trans-esterification. In this work, the esterification of acetic acid with isopropanol coupled with pervaporation has been investigated. First, the synthesis and hydrolysis of isopropyl acetate have been studied using the commercial ion exchange resin Amberlyst 15. The influence of different operating parameters such as reaction temperature, initial molar reactant ratio and amount of catalyst has been examined. Additionally, the performance of the commercial polymeric membrane PERVAP® 2201 has been studied. The influence of temperature and feed composition on the permeation characteristics of the membrane was analyzed, whereby preferential water permeation from the quaternary mixture involved in the esterification of acetic acid with isopropanol has been observed under the experimental conditions considered in this work.

Inorganic solid supported polymer acid catalyst – Sulfonated polystyrene grafted silica gel in liquid phase esterification

Sulfonated polystyrene grafted silica gel particles were synthesized for use as an acid catalyst in the liquid phase esterification of acetic acid with ethanol at 313–353 K. The synthesis of the grafted silica gel particles consists of three steps: polymerization, grafting, and sulfonation. The synthesized catalyst is non-cross-linked, non-swelling, and mechanically as well as chemically stable. It contains 29% covalently-bound sulfonated polystyrene chains that give an acid capacity of 0.99 mmol g −1. The kinetics of the grafted silica gel is as rapid as that of a commercial ion-exchange resin. Since the acid capacity of the grafted silica gel is only 25% of the ion-exchange resin, the catalytic activity of acid groups in the grafted silica gel is higher than in the resin. A pseudohomogeneous kinetic model provides a satisfactory fit for both catalysts.

Synthesis of methyl isobutyl ketone from acetone over metal-doped ion exchange resin catalyst

The kinetics of one-step synthesis of methyl isobutyl ketone from acetone was studied in the presence of the bifunctional commercial ion exchange resin, Amberlyst CH28 over a wide range of temperature, total pressure and catalyst loading in a batch reactor. An activity-based kinetic model is proposed to predict the observed results, with the non-idealities of the liquid phase being described using the UNIQUAC method. Formation of mesityl oxide was found to govern the overall rate of reaction. Low reaction rates were observed at higher conversion, possibly due to a pseudo-equilibrium caused by reversible deactivation of the catalyst as a result of formation of water in the reaction system. Simultaneous removal of water during the course of the reaction may result in an enhanced conversion.

Environmentally Benign Hardness Removal Using Ion-Exchange Fibers and Snowmelt

Many industrial unit operations and unit processes require near-complete removal of hardness to avoid scaling in heat-transfer equipment, fouling in membranes, and high consumption of detergents and sequestering chemicals in cooling and wash water. Lime softening and cation exchange are the most commonly used processes practiced to date for hardness removal. Herein, we report and discuss the results and attributes of a new hardness removal process using ion-exchange fibers (IX-fibers). Most importantly, the process uses harvested snowmelt (or rainwater) as the regenerant chemical along with sparged carbon dioxide. Consequently, the spent regenerant does not contain a high concentration of aggressive chemicals such as sodium chloride or acid like traditional ion-exchange processes nor does the process produce voluminous sludges similar to lime softening. The bulk of carbon dioxide consumed during regeneration remains sequestered in the aqueous phase as alkalinity. IX-fibers form the heart of the process. They are essentially thin cylindrical polymeric strands 10-20 microm in diameter. The weak-acid carboxylate functional groups reside near to the surface of these cylindrical fibers. Low intraparticle diffusional resistance is the underlying reason IX-fibers are amenable to efficient regeneration with snowmelt sparged with carbon dioxide. When the carbon dioxide partial pressure is increased to 6.8 atm, over 90% calcium desorption efficiency is obtained. On the contrary, commercial weak-acid ion-exchange resins in spherical bead forms are ineffective for regeneration with carbon-dioxide-sparged snowmelt due to extremely slow ion-exchange kinetics involving counter-transport of Ca2+ and H+.

Application of ion-exchange resins to the fractionation of metals in water

This article surveys the analytical strategies developed for the fractionation of heavy metals in natural occurring waters using commercial synthetic ion-exchange resins in various column or batch protocols. Different approaches to integrating physical fractionation by filtration or ultrafiltration with chemical sensing of specific groups of metals are presented. Ion-exchange-based procedures that enable the study of the dissociation kinetics of metal species are also reported. The usefulness, simplicity and convenience of ion-exchange-resin-based methods in fractionation analysis are discussed. In addition, attention is drawn to some selected aspects of sample storage and pre-treatment along with a warning about the quality control of measurements.

Biosorption of lead(II), cadmium(II), copper(II) and nickel(II) by anaerobic granular biomass

Biosorption is potentially an attractive technology for treatment of wastewater for retaining heavy metals from dilute solutions. This study investigated the feasibility of anaerobic granules as a novel type of biosorbent, for lead, copper, cadmium, and nickel removal from aqueous solutions. Anaerobic sludge supplied from a wastewater treatment plant in the province of Quebec was used. Anaerobic granules are microbial aggregates with a strong, compact and porous structure and excellent settling ability. After treatment of the biomass with Ca ions, the cation exchange capacity of the biomass was approximately 111 meq/100g of biomass dry weight which is comparable to the metal binding capacities of commercial ion exchange resins. This work investigated the equilibrium, batch dynamics for the biosorption process. Binding capacity experiments using viable biomass revealed a higher value than those for nonviable biomass. Binding capacity experiments using non-viable biomass treated with Ca revealed a high value of metals uptake. The solution initial pH value affected metal sorption. Over the pH range of 4.0–5.5, pH-related effects were not significant. Meanwhile, at lower pH values the uptake capacity decreased. Time dependency experiments for the metal ions uptake showed that adsorption equilibrium was reached almost 30 min after metal addition. It was found that the q max for Pb 2+, Cd 2+, Cu 2+, and Ni 2+ ions, were 255, 60, 55, and 26 mg/g respectively (1.23, 0.53, 0.87, and 0.44 mmol/g respectively). The data pertaining to the sorption dependence upon metal ion concentration could be fitted to a Langmiur isotherm model. Based on the results, the anaerobic granules treated with Ca appear to be a promising biosorbent for removal of heavy metals from wastewater due to its optimal uptake of heavy metals, its particulate shape, compact porous structure, excellent settling ability, and its high mechanical strength.

Carbon adsorbents from waste ion-exchange resins

A series of activated carbons was prepared from different waste commercial ion-exchange resins and studied by means of adsorption, SEM and IR methods. Samples were additionally washed or washed/frozen. This resulted in increases in micro- and mesoporosity in comparison with initial activated carbons. For some samples, the latter treatment gives enhancement of mesoporosity but reduction of microporosity and vice versa comparing with only washed carbons due to different localization of water droplets in mesopores or micropores. Changes in the morphology of chars and activated samples depended on resin composition and history. Relatively high values of porosity ( V p ≈ 0.4 cm 3/g) and specific surface area ( S BET ≈ 600 m 2/g) show that activated carbons prepared from waste ion-exchange resins can be utilized for different purposes, especially after additional treatment (such as washing, impregnation by certain compounds and subsequent thermal activation).

Conversion, Selectivity, and Kinetics of the Dehydration of 1-Pentanol to Di-n-Pentyl Ether Catalyzed by a Microporous Ion-Exchange Resin

Selectivity, yield, and kinetics of the liquid-phase dehydration of 1-pentanol to di-n-pentyl ether were studied experimentally over a commercial gel-type ion-exchange resin with 4% of cross-linking in the temperature range 120−150 °C at 1 MPa in a continuous stirred tank reactor. Selectivities to ether higher than 96% were obtained at all temperatures for space times greater than 5 g h mol-1. However, the obtained maximum yield is only 0.22 of 1. The best kinetic model stems from a mechanism in which 1-pentanol, adsorbed on one center, reacts with 1-pentanol from the liquid phase to give the ether adsorbed. The surface reaction is assumed to be the rate-limiting step, in which only one center takes part.

Kinetic Modeling of the Dimerization of Isobutene

The dimerization of isobutene (2-methylpropene) produces diisobutenes (2,4,4-trimethylpentenes) that can be used as high-octane gasoline components. The dimerization kinetics were studied in experiments carried out in a continuous stirred tank reactor at 60−120 °C with different feed concentrations. A commercial ion-exchange resin catalyst was used together with tert-butyl alcohol (2-methyl-2-propanol), which increases the selectivity for diisobutenes by reducing the activity of the sulfonic acid sites of the resin. Langmuir−Hinshelwood-type kinetic models were derived for the dimerization and trimerization reactions, and their parameters were estimated on the basis of the measured data. The only model to represent the data successfully was one where diisobutenes form using two active sites and triisobutenes via diisobutenes using three active sites. This type of model well describes the triisobutene formation rate and the observed maximum in the diisobutene rate. The apparent activation energy was 30 kJ/mol for dimerization.

Efficient H2O2 Oxidation of Organic Pollutants Catalyzed by Supported Iron Sulfophenylporphyrin under Visible Light Irradiation

An efficient method has been developed to degrade toxic and nonbiodegradable organic pollutants such as Sulforhodamine B (SRB) and 2,4-dichlorophenol (DCP). It is based on the photocatalytic power of iron tetrasulfophenylporphyrin supported on a commercial anionic ion-exchange resin (Amberlite IRA 900) (FePR) to activate an oxidant H2O2 in aqueous media. Visible light irradiation (λ > 450 nm) significantly accelerates the degradation process. The new catalyst is effective over a wide pH range, and can be easily recycled by filtration. The SRB and DCP were mineralized with yields of 56% and 68% at a catalyst/substrate molar ratio of 1:33 and 1:535, respectively. Moreover, the supported-catalyst would suppress greatly the undesirable side-reaction of H2O2 conversion to O2. UV−vis spectroscopy, high-performance liquid chromatography, ion chromatography, IR, spin-trapping electron paramagnetic resonance, surface photovoltage spectroscopy, and total organic carbon measurements were used to examine the photorea...

Selective synthesis of Bisphenol-A over mesoporous MCM silica catalysts functionalized with sulfonic acid groups

Mesoporous MCM-41 and -48 silicas anchored with sulfonic acid (SO 3H) groups via postsynthesis modification are very effective for the synthesis of Bisphenol-A by liquid-phase condensation of phenol with acetone. Higher amounts of thiol groups can be incorporated in MCM-48 silicas presumably due to the presence of larger number of surface silanol groups. However sulfur K-edge XANES spectroscopy reveals that effective oxidation of the precursor thiol (SH) groups to the sulfonic acid (SO 3H) groups was necessary for obtaining samples of good catalytic activity. It was noted that when sulfur loadings exceed 1.5 meq/g solid a part of the sulfur atoms remains in the reduced form even after prolonged oxidation. MCM-41 silica anchored with sulfonic acid groups has comparable catalytic activity to that of commercial ion-exchange resin Amberlite-120 and the former also showed higher selectivity toward the desired p, p′ isomer. MCM-48 silica-anchored samples are equally effective for selective synthesis of Bisphenol-A.

Synthesis of ultra fine transition metals in immobilised microreactors

The possibility obtaining ultra fine metals in molecular microreactors (cavities of immobilized calixarenes, polyelectrolytes) when reducing metal complexes in a polymeric matrix has been demonstrated. Commercial ion exchange resins and network polymers with immobilized cis-calixarenes were used as polymeric microreactors. Tetra-ammine complexes of transition metals Pd, Cu, Ni were introduced in cation exchange resins by ion exchange. According to X-ray powder diffraction data, reduction of transition metal complexes in the polymeric matrix givesmetallic particles of 20–100 nm size.

Catalytic activity of silica supported sulfated zirconia catalysts for liquid phase etherification of C 6 olefins with alcohols

Etherification of certain C 6 olefins with alcohols over a commercial ion-exchange resin and some supported sulfated zirconia catalysts was investigated. The commercial resin catalyst Amberlyst 15 shows nonselective to ether production. Silica-supported sulfated zirconia shows a comparable and even higher ether yield than the commercial resin while the catalytic activity is dependent on zirconium precursors, preparation technique, calcination temperature, ratio of SZ on silica, and reaction temperature. Addition of promoters, transition metal oxides, will also influence the catalytic activity while depending on the nature of promoter. Ni and Pt increase the catalytic activity and Fe shows no significant influence on olefin conversion whereas Mn reduces the catalytic activity. However, these promoters reduce the ether selectivity and ether yield. Silica-supported SZ catalysts also exhibit varying activities for etherification of different olefins and alcohols.

Separation of Phenylenediamines by Selective Solubilization and Adsorption on Ion-Exchange Resin

Separation of phenylenediamines (PDAs) was attempted using a combination of selective solubilization in an organic solvent and then adsorption from nonaqueous solutions on commercial acidic ion-exchange resins. Toluene was the best solvent for selective solubilization and also for the subsequent sorption of the amines by an acidic ion-exchange resin having sulfonic acid groups on the styrene-divinylbenzene backbone. The equilibrium sorption studies showed very selective sorption of the amines with a high loading capacity on the resin. The uptake of the amines was reinforced by Lewis acid–base interaction between the lone pair of electrons on the nitrogen of the amine and the sulfonic acid group of the resin. In the sorption studies involving mixtures, p-PDA was selectively adsorbed. Molecular mechanics calculations confirm the existence of the acid–base interactions.

Adsorption and desorption characteristics of zinc on ash particles derived from oil palm waste

AbstractSolid waste such as palm fibre and shell produced by the palm oil industry is used by palm oil mills as boiler fuel to produce steam for electricity generation. The ash produced after combustion creates a disposal problem for the palm oil industry. This study explored the potential of oil palm ash as an adsorbent material for removal and recovery of zinc ions from aqueous solutions. The equilibrium uptake of zinc was found to increase with solution pH in the range 3–6, yielding a maximum adsorption capacity of 0.163 mmol g−1 of ash at a pH of 6. The affinity constant of oil palm ash was found to greatly exceed that of a commercial ion exchange resin, suggesting that oil palm ash may find potential application in treating dilute zinc‐containing waste streams. Four isotherm models were used to fit the constant pH equilibrium isotherms obtained at four different pH values. The entire data set was successfully simulated using two of the isotherm models: a Langmuir model with pH‐dependent parameters and an extended Langmuir–Freundlich model with pH‐independent parameters. The rates of adsorption and desorption for zinc were measured using a stirred‐batch contactor. The contact time required to reach apparent adsorption equilibrium was found to decrease with increasing adsorbent dosage. Both the rate and the extent of zinc desorption were affected by the pH of the desorbing solution. The adsorption and desorption rates were consistent with simple first‐order rate models.© 2002 Society of Chemical Industry

Etherification of dimethylbutene with methanol over clay-based acid catalysts

Etherification of a typical C6 olefin, 2,3-dimethyl-1-butene, with methanol was investigated over commercial ion-exchange resins and several clay-based acid solids prepared by sulfuric acid treatment or impregnation of sulfated zirconia and Nafion. The commercial resin catalyst Amberlyst 15 is effective but nonselective to ether production, while Nafion is less active. For two clay systems, montmorillonite-based catalysts generally exhibit higher activities than bentonite and MT-H2SO4will be a highly active and selective catalyst than the supported sulfated zirconia and Nafion.