Acid Ion Exchange Research Articles

Removal of Co(II) from aqueous solutions by NKC-9 strong acid resin

A strong acidic ion exchange resin (NKC-9) was used as a new adsorbent material for the removal of Co(II) from aqueous solutions. The adsorption isotherm follows the Langmuir model. The maximum adsorption capacity of the resin for Co(II) is evaluated to be 361.0 mg/g by the Langmuir model. It is found that 0.5 mol/L HCl solution provides effectiveness of the desorption of Co(II) from the resin. The adsorption rate constants determined at 288, 298 and 308 K are 7.12×10 −5, 8.51×10 −5 and 9.85×10 −5 s −1, respectively. The apparent activation energy ( E a) is 12.0 kJ/mol and the adsorption parameters of thermodynamic are Δ H Θ =16.1 kJ/mol, Δ S Θ=163.4 J/(mol·K), Δ G Θ 298 K=-32.6 kJ/mol, respectively. The adsorption of Co(II) on the resin is found to be endothermic in nature. Column experiments show that it is possible to remove Co(II) ions from aqueous medium dynamically by NKC-9 resin.

Di-d-fructose Dianhydride-Enriched Caramels: Effect on Colon Microbiota, Inflammation, and Tissue Damage in Trinitrobenzenesulfonic Acid-Induced Colitic Rats

In the present study we describe the preparation and chemical characterization of a caramel with a high (70%) content of difructose dianhydrides (DFAs) and glycosylated derivatives (DFAs). This product was obtained by thermal activation (90 degrees C) of highly concentrated (90% w/v) aqueous D-fructose solutions using the sulfonic acid ion-exchange resin Lewatit S2328 as caramelization catalyst. DFAs represent a unique family of cyclic fructans with prebiotic properties already present in low proportions (<15%) in commercial caramel. We report the antiinflammatory activity of the new DFA-enriched caramel in the trinitrobenzenesulfonic acid (TNBS) model of rat colitis, an experimental model that resembles human inflammatory bowel disease (IBD), and compare its effects with those obtained with a commercial sucrose caramel and with linear fructooligosaccharides (FOS). For this purpose, the effects on colon tissue damage, gut microbiota, short-chain fatty acid (SCFAs) production, and different inflammatory markers were evaluated. The administration of DFA-enriched caramel to colitic rats showed intestinal antiinflammatory effect, as evidenced macroscopically by a significant reduction in the extent of the colonic damage induced by TNBS. This effect was similar to that obtained with FOS in the same experimental settings, whereas commercial caramel was devoid of any significant antiinflammatory effect. The beneficial effect was associated with the inhibition of the colonic levels of the proinflammatory cytokines, tumor necrosis factor alpha (TNF alpha) and interleukin 1beta (IL-1beta), and the reduction in colonic myeloperoxidase (MPO) activity and inducible nitric oxide synthase (iNOS) expression. The DFA-enriched caramel also promoted a more favorable intestinal microbiota, increasing lactobacilli and bifidobacteria counts as well as inducing higher concentrations of SCFAs in the luminal colonic contents. These results reinforce the concept of DFAs and glycosyl-DFAs as dietary beneficial compounds with prebiotic properties and suggest that the novel DFA-enriched caramel here reported may be an interesting candidate to be explored for the dietary treatment of human IBD.

Preparation and characterization of PVC/PS composite cation exchange fibers and their adsorption properties on aniline

AbstractBased on the composite fibers made from polyvinylchloride (PVC) and polystyrene (PS), the composite fibers obtained were further crosslinked and sulphonated with 50% oleum to produce the acidic cation ion exchange fibers. The optimal technology of the fibers obtained were discussed, the structures of the fibers thus obtained were investigated by using Fourier transform infrared (FTIR) spectrophotometry, thermogravimetry analysis (TG), differential thermogravimetry analysis (DTG), and scaning electron microscope (SEM) etc. Their properties were measured using chemical titration, filament mightiness instrument, etc. The absorption kinetics and the main factors affecting absorption capacity on aniline were studied, and their regenerating properties were probed. The results indicated that the cation exchange fibers with better mechanical property and higher exchange capability were obtained. The fibers had bigger hydrophilicity, better ability of acid, and alkali corrosion resistance, so they had better practical application value. This type of ion exchange fibers had faster absorption property and better working stability to aniline and could be used repeatedly, so they were applied for treatment of waste water containing aniline with a promising prospect. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Isoamylene Trimerization in Liquid-Phase over Ion Exchange Resins and Zeolites

Liquid-phase trimerization of 2-methyl-1-butene and 2-methyl-2-butene mixtures over solid acid catalysts was carried out in a batch-stirred tank reactor in the temperature range 333−373 K. Diisoamylenes and triisoamylenes were the main products. Cracking products among C6−C9 and C11−C14 were also obtained under the assayed conditions. The catalityc performance of five different acidic ion exchange resins (Amberlyst 15, Amberlyst 35, Amberlyst 70, Purolite CT-252, Purolite CT-276) and four zeolites (H-BEA-25, H-FAU-30, H-FAU-6 and H-MOR-20) was assessed. Experimental results showed that Amberlyst 15 and H-FAU-30 were the best catalysts for isoamylene trimerization, with selectivities above 40% at 373 K. The most influencing physical properties of the catalysts on the selectivity toward dimers and trimers were acid capacity, acid strength, and specific surface area for resins, and microporous surface area for zeolites. Isoamylene trimerization extent was larger at higher temperature. The most probable mecha...

Recovery of cellulases by adsorption/desorption using cation exchange resins

Cellulases from Trichoderma reesei were recovered by adsorption in sodium acetate buffer at lower pH using cation exchange resins followed by desorption at higher pH. The weakly acidic ion exchange resin WK10 was found to be the best among the six resins tested in terms of the enzyme activity recovery. The optimal pH values for the adsorption and desorption were 4.0 and 8.0, respectively, and the optimal adsorption and desorption times were both 5 h. Almost 100% of the initial cellulase activity was recovered under the optimal conditions with the supplement of β-glucosidase, which was unable to be efficiently recovered due to its strong adsorption (95.7%) but poor desorption (1.9%).

Cross-Contamination Test of an Enthalpy Wheel Loading a Strong Acidic Cation Ion-Exchange Resin or 3A Zeolite as a Desiccant Material

Enthalpy wheels have been widely used for achieving comfortable air-conditioning with low energy consumption. Desiccant materials such as silica gel and molecular sieves are used so as to give it a latent heat exchanging function. However, this important function has become the cause of cross-contamination because substances with offensive odors are also adsorbed onto desiccants. In this study, cross-contamination of an enthalpy wheel consisting of ion-exchange resin particles as a desiccant material is examined and compared with a commercialized 3A zeolite wheel. It is found that the ion-exchange resin type wheel shows a smaller cross-contamination ratio than the other for all contaminants tested in this study, i.e. ammonia, carbon dioxide, formaldehyde and propane, although water-soluble and smaller contaminants such as ammonia still indicated a higher contamination ratio.

Low Temperature De-acidification Process of Animal Fat as a Pre-Step to Biodiesel Production

An esterification process is proposed to lower Free Fatty Acids (FFA) content in waste animal fat using solid acid ion exchange resins as catalysts. The final aim is to make this material a suitable feedstock for biodiesel production. Its exploitation does not interfere with the food chain, besides allowing to lower biodiesel production costs.

Natural zeolites as effective adsorbents in water and wastewater treatment

Natural zeolites are abundant and low cost resources, which are crystalline hydrated aluminosilicates with a framework structure containing pores occupied by water, alkali and alkaline earth cations. Due to their high cation-exchange ability as well as to the molecular sieve properties, natural zeolites have been widely used as adsorbents in separation and purification processes in the past decades. In this paper, we review the recent development of natural zeolites as adsorbents in water and wastewater treatment. The properties and modification of natural zeolite are discussed. Various natural zeolites around the world have shown varying ion-exchange capacity for cations such as ammonium and heavy metal ions. Some zeolites also show adsorption of anions and organics from aqueous solution. Modification of natural zeolites can be done in several methods such as acid treatment, ion exchange, and surfactant functionalisation, making the modified zeolites achieving higher adsorption capacity for organics and anions.

Kinetic Study of Esterification of Lactic Acid with Isobutanol and n-Butanol Catalyzed by Ion-exchange Resins

The esterification reactions of lactic acid with isobutanol and n-butanol have been studied in the presence of acid ion-exchange resin Weblyst D009. The influences of catalyst loading, stirrer speed, catalyst particle size, initial reactant molar ratio and temperature on the reaction rate have been examined. Experimental kinetic data were correlated by using the Pseudo-homogeneous, Langmuir-Hinshelwood and Eley-Rideal models. Nonideality of the liquid phase was taken into account by using activities instead of molar fractions. The activity coefficients were calculated according to the group contribution method UNIFAC. Provided that the nonideality of the liquid is taken into account, the esterification kinetics of lactic acid with isobutanol and n-butanol catalyzed by the acid ion-exchange resin can be described using all three models with reasonable errors.

Use of hydrometallurgical wastewater as a precursor for the synthesis of cryptomelane-type manganese dioxide ion exchange material

Cryptomelane-type manganese dioxide was synthesized in order to use it as ion exchange material for the removal of heavy metals from wastewaters. The synthesis was carried out using hydrometallurgical wastewater simulant that is very typical for mining industry after sulphuric acid leaching of the ore and the recovery of base metals. This raffinate simulant solution, consisting of Al, Fe, Mg, Mn, Ca and Na was used as precursor and pure cryptomelane-structured manganese dioxide was synthesized. The ion exchange properties of the cryptomelane were typical for weakly acidic ion exchangers with selectivity towards transition metals. The obtained capacity of 1.3 mmol/g for copper and distribution coefficient as high as ∼10 4 ml/g are promising for future applications in metal separation processes.

Catalytic etherification of glycerol by tert-butyl alcohol to produce oxygenated additives for diesel fuel

The heterogeneous catalytic etherification of glycerol with tert-butyl alcohol was investigated in presence of lab-made silica supported acid catalysts. As reference, two commercial acid ion-exchange resins were also used. Experiments were carried out in batch mode at T R ranging from 303 to 363 K. An increase in reaction temperature favors the formation of di-substituted ethers. The etherification reaction proceeds according to a consecutive path and the surface reaction between adsorbed glycerol and protonated tert-butanol (tertiary carbocation) can be considered as the rate determining step. Steric hindrance phenomena and water hinder the formation of tri-substituted ether (TBGE). As expected, water removal was necessary to allow the higher ethers formation. The specific activity (turnover frequency, TOF) of A-15 catalyst is significantly higher than that of the other studied acid systems, due to the wide pore diameter that allows an easier accessibility of the reagent molecules.

Preparation and application of acrylic acid grafted polytetrafluoroethylene fiber as a weak acid cation exchanger for adsorption of Er(III)

In this work, a weakly acidic ion exchange fiber (PTFE- g-AA) has been prepared by 60Co irradiation grafting with acrylic acid (AA) onto the polytetrafluoroethylene (PTFE) fiber. The grafted fiber was characterized by FTIR, SEM and TGA technique. The exchange capacity of the PTFE- g-AA fiber is 3.87 mmol/g. The adsorbent material was employed for Er(III) uptaking by batch and column experiments. Kinetics studies showed that the adsorption process obeyed pseudo-second-order kinetics. The adsorption isotherms followed both the Freundlich model and Langmuir model. The maximum adsorption capacity of the PTFE- g-AA fiber for Er(III) was evaluated to be 142.0 mg/g for the Langmuir model. It was found that 0.75 M HCl–0.25 M NaCl solution provided effectiveness of the desorption of Er(III) from the PTFE- g-AA fiber. Various thermodynamic parameters such as standard enthalpy (Δ H 0), standard entropy (Δ S 0) and standard free energy (Δ G 0) were evaluated. The adsorption of Er(III) on the PTFE- g-AA fiber was found to be endothermic in nature. The Thomas model was successfully applied to experimental data to predict the breakthrough curves and to determine the characteristics parameters of the column useful for process design.

Selective recovery of Cr and Cu in leachate from chromated copper arsenate treated wood using chelating and acidic ion exchange resins

The purpose of this study was to selectively remove chromium and copper from CCA-treated wood acid leachates (initial concentrations of 447–651 mg As l −1, 374–453 mg Cu l −1 and 335–622 mg Cr l −1) using ion exchange resins and precipitation techniques. Batch experiments revealed that the chelating resin Dowex M4195 had a high copper selectivity in the presence of chromium while the Amberlite IR120 resin had a high chromium sorption capacity. Combining M4195 and IR120 resins in four successive columns, made with Plexiglas tube, led to 96% copper extraction and 68% chromium extraction. NH 4OH (4 M) efficiently eluted copper from the chelating resin while H 2SO 4 (10% v/v) was used for IR120 resin elution. Copper and chromium recovery by elution reached 94% and 81%, respectively. Successive sorption and elution steps using M4195 and IR120 ion exchange resins presented similar metal removal capacities over the five cycles. No resin deterioration was observed but the results suggested arsenic bulk diffusion into the M4195 resin. Successive treatments of CCA-treated wood leachate with M4195 and IR120 allowed for copper and chromium removal while arsenic could be extracted by coagulation treatment with ferric chloride and precipitation with Ca(OH) 2 at pH 5.7. This final process led to 99.9% arsenic removal. The final effluent contained less than 1 mg l −1 of arsenic, chromium and copper.

Mechanisms of arsenic and lead release from hydrothermally altered rock

This paper describes the effects of pH, dissolved oxygen (DO), redox conditions, and mixing ratio of different rocks on the leaching behaviors of As and Pb from hydrothermally altered rock as well as the functional groups incorporating As and Pb in the rock. Most of As and Pb were incorporated in the residual or crystalline phase although significant amounts were also determined to be exchangeable, with carbonates and with Fe–Mn oxides. Under oxic conditions, As and Pb showed similar leaching behaviors at similar pH values, a higher mobilization in the acidic and alkaline regions and a minimum at circumneutral pH. The absence of DO restricted the oxidation of sulfide minerals that also contained significant quantities of As resulting in a lower As release under these conditions. Strongly reducing conditions favored the release of As by the reductive dissolution of Fe–Mn oxides and prevention of carbonate precipitation while the same conditions immobilized Pb because of its re-precipitation under reducing conditions. In general, depending on the pH, DO, and redox conditions, the major modes of As and Pb release from these sources could be either one or more of the following mechanisms: acid dissolution, reductive dissolution, ion exchange, desorption and sulfide oxidation processes.

New sulfonic acid ion-exchange resins for the preesterification of different oils and fats with high content of free fatty acids

The preesterification of free fatty acid (FFA) containing vegetable oils by strong acid ion-exchange resins was studied. The catalysts were characterized by scanning electron microscopy (SEM) and ion-exchange capacity. Based on a simple kinetic model the rate constants were determined. The effect of the catalyst structure, particle size, stirring speed, oil properties and water removal method on the reaction rate was investigated. Calculation of the turn over frequencies (TOFs) revealed high catalyst activities. Excellent conversions were obtained even without water removal, due to an extractive esterification. During recycling durability tests a catalyst activity loss occurred. The deactivation mechanism was investigated and the exhausted catalysts were successfully regenerated. A catalyst fouling was not observed. The presented preesterification process facilitates the processing of low quality, high FFA containing oils to biodiesel via basic transesterification and might help to reduce the production costs.

Purification of glycerol/water solutions from biodiesel synthesis by ion exchange: sodium and chloride removal. Part II

AbstractBACKGROUND: Equilibrium studies were carried out with the aim of finding the basic design parameters for ion exchange plants using a glycerol phase obtained from biodiesel production. The uptake of sodium and potassium ions on a strongly acidic ion exchanger, Amberlite IR‐120, in the proton form from glycerol/water mixtures has been studied. The effect on the selectivity towards sodium of the percentage of water in glycerine/water mixtures on the macroporous resin Amberlite 252 has been analyzed. Finally, chloride removal by a strongly basic anionic‐exchange resin Amberlite IRA‐420 at three different temperatures has been studied.RESULTS: The strongly acidic ion exchanger Amberlite IR‐120 exhibits higher selectivity for potassium versus sodium ions. The ideal mass action law model was able to fit the experimental equilibrium data. The equilibrium data obtained at different percentages of water in the glycerine/water mixture indicate that as the water content increased the resin selectivity for sodium uptake is reduced. The selectivity of the anion exchange resin Amberlite IRA‐420 for chloride ions decreases with temperature. The ideal mass action law was accurate enough to fit the equilibrium data of the three systems and allowed the equilibrium thermodynamic properties to be obtained.CONCLUSIONS: These results confirm that macroporous resin Amberlite 252 could be a good choice to remove sodium ions from glycerol/water solutions with a high salt concentration and also that a strongly basic anionic‐exchange resin could be used for chloride removal. Copyright © 2009 Society of Chemical Industry

Photodegradation of humic acid using spherical activated carbon contained Zn in a fluidized bed system

In this study, a strong acid ion-exchange resin, as the starting material of spherical activated carbon contained Zn (Zn-SPAC), was treated by 0.1 N zinc solution. Ion-exchange treatment was performed from one to three times for controlling the zinc content. The ion-exchanged resins were activated under N2/H2O vapor atmosphere at 900°C for 0.5 h, followed by carbonization treatment at 700°C under N2 atmosphere. The Zn-SPAC samples were measured for their physicochemical characteristics, such as X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) images, electron probe micro analyzer (EPMA) images, energy dispersive X-ray spectroscopy (EDXS), Brunauer–Emmett–Teller (BET) specific surface area, strength, and zinc content. Also, the samples were used in order to measure photochemical activities, such as the removal efficiency of humic acid (HA) in a fluidized batch reactor. The XRD patterns appeared as the ZnS type. The Zn-SPAC had a large BET specific surface area and their shape was spherical, with a diameter of about 350–400 μm. When the Zn-SPAC was dosed in a fluidized bed reactor with UV light, the HA removal efficiency increased by up to 60%. On the other hand, the HA removal efficiency by only UV-C (λ max = 254 nm) irradiation was very low, about 15%. Therefore, we infer that Zn-SPAC has good photochemical activity and presented the possibility of being a useful photocatalyst for water purification.

Purification of glycerol/water solutions from biodiesel synthesis by ion exchange: sodium removal Part I

AbstractBACKGROUND: In this study, equilibrium and kinetic data of the ion exchange of sodium from glycerol–water mixtures on the strong acid resin Amberlite‐252 were obtained. Basic parameters for the design of ion exchange units for the purification of the crude glycerol phase from biodiesel production have been determined.RESULTS: Equilibrium uptake of sodium ions with the strong acid ion exchanger Amberlite‐252 was studied at three temperatures. The Langmuir equation and the mass action law model were used to fit the experimental equilibrium data. Equilibrium constants and thermodynamic parameters were obtained at each temperature. Kinetic experiments were carried out to evaluate the effective diffusion coefficients of sodium on the resin Amberlite‐252 in glycerine–water media.CONCLUSIONS: Equilibrium results indicate that this process is favourable and also that its selectivity decreases with temperature increase from 303 to 333 K. Both models were able to fit the experimental equilibrium data. Kinetic experiments showed that the rate of mass transfer in this binary system is high. An Arrhenius type equation allowed the correlation of effective diffusion coefficients and temperature. The results indicate that the macroporous resin Amberlite‐252 could be useful for removal of sodium ions from glycerine/water solutions with a high salt concentration. Copyright © 2008 Society of Chemical Industry

Evaluating UV/H 2O 2 processes for methyl tert-butyl ether and tertiary butyl alcohol removal: Effect of pretreatment options and light sources

In this paper, we evaluate the efficiency of UV/H 2O 2 process to remove methyl tert-butyl ether (MtBE) and tertiary butyl alcohol (tBA) from a drinking water source. Kinetic models were used to evaluate the removal efficiency of the UV/H 2O 2 technologies with different pretreatment options and light sources. Two commercial UV light sources, i.e. low pressure, high intensity lamps and medium pressure, high intensity lamps, were evaluated. The following pretreatment alternatives were evaluated: (1) ion exchange softening with seawater regeneration (NaIX); (2) Pellet Softening; (3) weak acid ion exchange (WAIX); and (4) high pH lime softening followed by reverse osmosis (RO). The presence or absence of a dealkalization step prior to the UV/H 2O 2 Advanced Oxidation Process (AOP) was also evaluated for each pretreatment possibility. Pretreatment has a significant impact on the performance of UV/H 2O 2 process. The NaIX with dealkalization was shown to be the most cost effective. The electrical energy per order (EEO) values for MtBE and tBA using low pressure high output UV lamps (LPUV) and 10 mg/L H 2O 2 are 0.77 and 3.0 kWh/kgal-order, or 0.20 and 0.79 kWh/m 3-order, respectively. For medium pressure UV high output lamps (MPUV), EEO values for MtBE and tBA are 4.6 and 15 kWh/kgal-order, or 1.2 and 4.0 kWh/m 3-order, for the same H 2O 2 dosage.

Introduction of bifunctionality into the phosphinic acid ion-exchange resin for enhancing metal ion complexation

In nuclear industry the role of conventional strong cation exchange resins is limited as they function less in high acid media. The phosphorous group that has got more affinity towards actinide elements is chosen as a chelating group and the phosphinic acid ion exchange resin was synthesized. The extraction ability of the phosphinic acid resin for plutonium (Pu) from HNO 3 medium as well as from H 2SO 4 medium was studied. Though the resin shows better extraction for Pu than the strong cation exchanger resins at higher acidities, its kinetics is slow. In order to enhance the kinetics as well as to improve upon selectivity, a sulphonic group is introduced into the phosphinic acid resin. To verify the effect of bifunctionality extraction studies have been carried out with Pu from different acid media of varying concentrations. Sulphonated phosphinic acid resin shows a 2-fold increase in distribution coefficient ( k d ) as well as it reached equilibrium very fast compared to the phosphinic acid resin. It is postulated that the sulphonic acid ligand provides an access mechanism for the metal ions into the polymer matrix while it is the phosphinic acid group that is responsible for selective coordination of metal ions. Thus bifunctionality is coupling of an access mechanism to a recognition mechanism. The experiments carried out demonstrated the applicability of sulphonated phosphinic acid resin in the nuclear industry.