Strong Base Ion Exchange Resin Research Articles

A SUSTAINABLE APPROACH TO IMPROVEMENT OF CORROSION PROTECTION COATINGS FOR STEEL STRUCTURES

Corrosion is a primary factor compromising the safety and service life of steel structures. Corrosion protection coatings are generally employed for protection of the steel structures that are exposed to different aggressive environments. This research evaluated the use of biobased ion exchangers as a sustainable means of improving corrosion protection coatings.
 Two base polymer coatings (vinyl and coal-tar epoxy) were considered. The following types and dosages of biobased ion exchangers were evaluated in these coatings: (i) strong-base ion exchange cellulose in OH, PO4, SiO3, BO3, NO2, SO4 and NO3 forms at 1% by weight of resin; (ii) weak-acid starch citrate ion exchanger in H form at 1 wt.%; and (iii) strong-base ion exchange cellulose in OH form at 2 wt.%. In addition, a strong-base ion exchange resin in OH form was considered at 1 and 2 wt.% as control. Different coating formulations were evaluated based on the outcomes of salt-fog corrosion, moisture resistance, pull-off strength, and abrasion resistance tests. The introduction of certain biobased ion exchangers in protective coatings was found to be an effective means of achieving improved levels of corrosion resistance, adhesion capacity, moisture stability and abrasion resistance.

Removal of sulfate ions from process water by ion exchange resins

High concentrations of sulfate and thiosulfate ions in the process water may cause significant problems in the flotation of sulfide ores through changing the pulp chemistry, surface chemistry of sulfide minerals and froth stability. In addition to that formation of colloidal gypsum and scaling problems in process plants are observed when lime is used for pH regulation. Therefore, reducing sulfate and thiosulfate ion concentration in the process water is required for minimizing gypsum formation and stabilizing pulp chemistry. In this study, strong base ion exchange resins; Amberlite IRA-400 and Dowex 1X2 were used to reduce the amount of sulfate and thiosulfate in the process water.Adsorption and regeneration behavior of resins were determined by bench scale laboratory experiments using synthetic water simulating the process water of a zinc flotation plant from an Iberian Mine (Portugal). In the second phase of the study, the resins were tested using the process water in the mine site. Batch scale flotation tests were conducted by using the process water treated with Amberlite IRA-400 to determine the effects of water treatment on flotation efficiency of the Zinc ore.Amberlite IRA-400 has higher degree of cross-linkage in its structure and higher adsorption capacity. More than 90% of the sulfate could be removed from the water in the first 5 min of the adsorption test. The resin has high adsorption kinetics and can remove majority of the anions by adjusting the required quantity of resin according to the concentration of dissolved ions in the process water. The resins were regenerated effectively by using 4% w/v NaOH solution as a regenerant and used multiple times for adsorption. The same regeneration solution could be used with stage addition of NaOH to achieve the balance between hydroxide ions and adsorbed ions.Effects of resin treated water on flotation efficiency and water chemistry profile in the grinding and flotation stages were investigated using an ore sample taken from the Zn flotation plant. The results show that concentration of all ions increased significantly after the grinding stage due to dissolution of the minerals. Water treatment by resins removed majority of sulfate and thiosulfate ions from the flotation water. Water treatment by ion exchange resins increased the pulp pH up to 12, due to the ion exchange reaction between the hydroxide ions and anions. However, high pH did not significantly affect Zn flotation efficiency.

Opportunities for coupled electrochemical and ion-exchange technologies to remove recalcitrant micropollutants in water

Micropollutants are found in many waters at concentrations that are concerning for living and environmental systems. They are usually characterised as being persistent and are generally difficult to remove from the water using traditional techniques. In this work, we investigate a treatment technology that couples electrooxidation of micropollutants with subsequent absorption of charged products and remaining compounds through a mixed strong acid and strong base ion exchange resin. The results clearly show that carbon fibre is a promising electrode material. Electrooxidation of the drug Ibuprofen using carbon fibre in a coulombic efficiency of 13 mC/ppm removed 71% of the compound after two hours (down to 29 ppm). The addition of sodium chloride led to a near doubling of the pseudo-first order reaction rate from 1.7 to 3.0 10−4 s−1. A mix of Ibuprofen and the pesticide Diuron showed similarly promising results and while the overall oxidation decreased the positive effect of sodium chloride was present. Strikingly, coupling electrooxidation with a mixed bed ion exchange resin removed both compounds, decreasing levels of Diuron to below the limit of detection (18 ppb) and Ibuprofen down to 0.8 ppm. The approach shows potential as a treatment technology for the removal of complex pollutants in water.

Nano-enabling of strong-base ion-exchange media via a room-temperature aluminum (hydr)oxide synthesis method to simultaneously remove nitrate and fluoride

This study demonstrated a new room-temperature method for synthesizing aluminum (hydr)oxide material inside the pores of strong-base ion-exchange resin to fabricate a novel class of hybrid media capable of simultaneously removing nitrate and fluoride as model groundwater contaminants. The aluminum (hydr)oxide hybrid media was fabricated by reducing aluminum ion precursors with borohydride within ion-exchange resin at room temperature, followed by exposure to environmental oxygen. The hybrid media was characterized, and its performance to simultaneously remove nitrate and fluoride was determined in simple and complex water matrices using short-bed column tests operated under conditions realistic for point-of-use systems. Results revealed that, although not optimized, aluminum (hydr)oxide hybrid media was able to simultaneously remove nitrate and fluoride, which was not possible with neither unmodified strong-base ion-exchange resin nor conventional granular activated alumina alone. Future modifications and optimizations of this relatively simple and inexpensive fabrication process have the potential to yield an entire class of hybrid media suitable for point-of-use/point-of-entry water treatment systems.

Fundamental aspects related to batch and fixed-bed sulfate sorption by the macroporous type 1 strong base ion exchange resin Purolite A500

Acid mine drainage is a natural process occurring when sulfide minerals such as pyrite are exposed to water and oxygen. The bacterially catalyzed oxidation of pyrite is particularly common in coal mining operations and usually results in a low-pH water polluted with toxic metals and sulfate. Although high sulfate concentrations can be reduced by gypsum precipitation, removing lower concentrations (below 1200 mg/L) remains a challenge. Therefore, this work sought to investigate the application of ion exchange resins for sulfate sorption. The macroporous type 1 strong base IX resin Purolite A500 was selected for bath and fixed-bed sorption experiments using synthetic sulfate solutions. Equilibrium experiments showed that sulfate loading on the resin can be described by the Langmuir isotherm with a maximum uptake of 59 mg mL-resin−1. The enthalpy of sorption was determined as +2.83 kJ mol−1, implying an endothermic physisorption process that occurred with decreasing entropy (−15.5 J mol−1.K−1). Fixed-bed experiments were performed at different bed depths, flow rates, and initial sulfate concentrations. The Miura and Hashimoto model predicted a maximum bed loading of 25–30 g L-bed−1 and indicated that both film diffusion (3.2 × 10−3 cm s−1 to 22.6 × 10−3 cm s−1) and surface diffusion (1.46 × 10−7 cm2 s−1 to 5.64 × 10−7 cm2 s−1) resistances control the sorption process. It was shown that IX resins are an alternative for the removal of sulfate from mine waters; they ensure very low residual concentrations, particularly in effluents where the sulfate concentration is below the gypsum solubility threshold.

Removal of Acetic Acid from Spent Sulfite Liquor Using Anion Exchange Resin for Effective Xylose Fermentation with Pichia stipitis

Acetic acid is one of the major inhibitors of spent sulfite liquor (SSL) fermentation for ethanol production. The objective of this study was to remove acetic acid from hardwood SSL using anion exchange resin in order to achieve effective fermentation with Pichia stipitis CBS6054. Lignosulfonate, as well as sulfate and sulfite ions in the SSL hindered the removal of acetic acid by anion exchange resins. CaO treatment was an effective method for removing these materials from SSL, which facilitated the removal of acetic acid in the subsequent ion exchange resin treatment. A two-stage strong base ion exchange resin (OH- form) treatment removed approximately 90% of the acetic acid from CaO-treated SSL, which decreased the acetic acid concentration to less than 1 g/L. The combined treatment of CaO and ion exchange resin treatments in a relatively short time achieved the selective removal of acetic acid from SSL and significantly increased the ethanol production from SSL.

A novel electrochemical ion exchange system and its application in water treatment

A novel electrochemical ion exchange system with porous cylinder electrodes is proposed for treatment of wastewater. This system can be used for desalination without the costly ion-exchange membrane and extra chemical reagents. Since the electrodes are completely uniform and no ion-exchange membrane was used in this system, it can be operated by switching anodes and cathodes flexibly for eliminating the scaling on the surface of electrodes. The strong base ion-exchange resin grains placed among the anode and cathode have played as supporting electrolyte, which is capable for the treatment of wastewater with low conductivity. The concentrated and neutralized anolyte containing chlorine is effective for disinfection and contaminants removal. Under the experimental conditions, the removal percentage of total dissolved salts was 83% and the removal percentage of chemical oxygen demand was 92% without consumption of extra chemical reagents.

Deionization of Coagulated, Clarified, Turbid Gauri Shankar Lake Waters by Using Ion-Exchange Technology

Water collected from a rain fed Gauri Shankar Lake, Bhavnagar, Gujarat, India was used for this study. It was clarified by giving treatment with alum and poly aluminum chloride (PAC) to remove suspended impurities present in it. Waters having turbidity value of 100–750 NTU (Nephelometric Turbidity Units) were treated with PAC and alum. The dosage of PAC required for the treatment was 60% less as compared with alum. The clarified water was passed through columns loaded with strong acid and strong base ion-exchange resins to obtain deionized water. The experiments were carried out for 100 cycles of exhaustion and regeneration. The effect of the coagulation process conditions on ion-exchange capacity, and the physical attrition of the ion-exchange resins were studied intensively. Also, the performance of ion-exchange resins was compared with virgin ground waters from the institute's well. The resins employed in the study were subjected to EDX (Energy Dispersive X-Ray Spectroscopy) analysis to find out the presence of coagulating ions adsorbed on the resins. The resins were also subjected to SEM (Scanning Electron Microscope) analysis to find changes on their surface due to adhering materials if any.

A proposed mechanism for nitrate and thiocyanate elution of strong-base ion exchange resins loaded with copper and gold cyanocomplexes

The use of ion exchange resins for the recovery of gold cyanide and other base metal cyanocomplexes has been hindered by poor elution, among other factors. To overcome this drawback, saline solutions have been proposed as an eluant for the loaded cyanocomplexes, with nitrate and thiocyanate being the most promising. In the present work, the elution of gold- and copper-cyanocomplexes from polyacrylic- and polystyrene-based resins at 50 °C was studied. The results showed that copper cyanide was easily eluted from polyacrylic- and polystyrene-based ion exchange resins using either 1 mol/L SCN − or NO 3 - . However, there was poor elution of the gold cyanide complex from the polystyrene-based resins using nitrate solutions, reflecting the higher affinity that gold cyanide presents for the latter. Conversely, gold elution reached 90% using thiocyanate. Therefore, the separation of gold and copper is possible using polystyrene resins, eluting first with nitrate and then with thiocyanate. Raman spectra have shown the presence of gold and also copper complexes in the resin beads, as well as in the eluate produced during elution of both the resins, suggesting that elution takes place by an ion exchange mechanism. The better performance observed using thiocyanate, as compared to nitrate, is discussed, based on the features of both ions.

Simultaneous removal of perchlorate and arsenate by ion-exchange media modified with nanostructured iron (hydr)oxide

Hybrid ion-exchange (HIX) media for simultaneous removal of arsenate and perchlorate were prepared by impregnation of non-crystalline iron (hydr)oxide nanoparticles onto strong base ion-exchange (IX) resins using two different chemical treatment techniques. In situ precipitation of Fe(III) (M treatment) resulted in the formation of sphere-like clusters of nanomaterials with diameters of ∼5 nm, while KMnO 4/Fe(II) treatments yielded rod-like nanomaterials with diameters of 10–50 nm inside the pores of the media. The iron content of most HIX media was >10% of dry weight. The HIX media prepared via the M treatment method consistently exhibited greater arsenate adsorption capacity. The fitted Freundlich adsorption intensity parameters ( q = K × C E 1 / n ) for arsenate (1/ n < 0.6) indicated favorable adsorption trends. The K values ranged between 2.5 and 34.7 mgAs/g dry resin and were generally higher for the M treated media in comparison to the permanganate treated media. The separation factors for perchlorate over chloride ( α C l − Cl O 4 − ) for the HIX media were lower than its untreated counterparts. The HIX prepared via the M treatment, had higher α C l − Cl O 4 − than the HIX obtained by the KMnO 4/Fe(II) treatments suggesting that permanganate may adversely impact the ion-exchange base media. Short bed adsorber (SBA) tests demonstrated that the mass transport kinetics for both ions are adequately rapid to permit simultaneous removal using HIX media in a fixed bed reactor.

The use of ion exchange resins for the treatment of cyanidation tailings. Part 2––pilot plant testing

This article reports the results of a pilot plant test on the use of ion exchange resins for the treatment of cyanide contaminated liquors arising from gold cyanidation. The tests were conducted on 14,000 m 3 of contaminated liquor, leftover from a previous operation in a gold mine in Australia. Prior to treatment, the liquor contained 45–65 mg/l CN TOT (total cyanide). Purolite A500 strong base ion exchange resin was used to adsorb cyanide species from the liquor. After adsorption, an oxidative acid eluent containing H 2O 2 and H 2SO 4 was used to regenerate the resin. The treatment reduced the cyanide contamination in the liquor to less than 2.5 mg/l CN TOT. Precious metals in the liquor were recovered and the revenue from precious metals contributed to offset the cost of cyanide detoxification. Base metals in the contaminated liquor were concentrated in the spent eluent stream. Resin deterioration, marked by a gradual reduction of the loading capacity of the resin was observed, most likely due to the precipitation of copper–iron cyanide on the resin. The deterioration of resin is drawback of this process and could hinder commercialisation of it. Hence further work should be undertaken to determine techniques to minimise the deterioration of resin.

Efeito estrutura da matriz na adsorção de cianocomplexos metálicos em resinas de poliestireno

O objetivo desse trabalho é a utilização de resinas de troca-iônica, base forte, na adsorção de cianocomplexos metálicos, visando a sua reciclagem. São utilizadas soluções sintéticas que simulam diferentes efluentes da lixiviação do minério de ouro, contendo concentrações de ferro, de zinco e de cobre, variando entre 50 e 500mg/l. São realizados ensaios de adsorção, em batelada, utilizando dois tipos de resinas comerciais: Ionac SR-7 (matriz de poliestireno, tripropilamônio quaternário como grupo de troca) e Dowex 1X8 (matriz de poliestireno, trimetilamônio quaternário como grupo de troca). Em ambas resinas houve uma adsorção maior do cianocomplexo de zinco com relação aos outros cianocomplexos metálicos existentes em solução. A ordem do carregamento, nesse caso, foi Zn&gt;Cu&gt;Fe. A resina Dowex 1X8 apresentou um maior carregamento dos cianocomplexos de zinco e de cobre, quando comparados com os carregamentos da outra resina. As diferentes afinidades são discutidas em função das características físico-químicas dos complexos e das estruturas das resinas.

Cyanide recovery by ion exchange from gold ore waste effluents containing copper

The recovery of cyanide from waste effluents of the cyanidation process in gold extraction plants is important environmentally and economically. In this respect ion exchange is being tested as a possible economic and versatile method for gold ores containing copper minerals. The present study shows the potential of strong and weak base ion exchange resins, particularly the former, for separating copper cyanide complexes from these industrial effluents, and in particular the feasibility of elution with different eluants. Three possible reagents are proposed for use with these resins and the industrial effluents as load solutions: NaCN, NaSCN and NaNO3. The recovery of copper complexes from industrial effluents using a strong base resin, Lewatit MP-500, and NaSCN as eluant solution, is very high, with recoveries of over 90% in each step. Problems arise when several cycles of load and elution are carried out with the resin, and the performance of the resin decreases when working with unfiltered solutions after several operational cycles.

Cyanide recovery by ion exchange from gold ore waste effluents containing copper

The recovery of cyanide from waste effluents of the cyanidation process in gold extraction plants is important environmentally and economically. In this respect ion exchange is being tested as a possible economic and versatile method for gold ores containing copper minerals. The present study shows the potential of strong and weak base ion exchange resins, particularly the former, for separating copper cyanide complexes from these industrial effluents, and in particular the feasibility of elution with different eluants. Three possible reagents are proposed for use with these resins and the industrial effluents as load solutions: NaCN, NaSCN and NaNO 3. The recovery of copper complexes from industrial effluents using a strong base resin, Lewatit MP-500, and NaSCN as eluant solution, is very high, with recoveries of over 90% in each step. Problems arise when several cycles of load and elution are carried out with the resin, and the performance of the resin decreases when working with unfiltered solutions after several operational cycles.

Telechelic oligo(2,3-dihydroxypropylmethacrylate acetonide)s with aldehyde end functionality prepared by ozonolytic cleavage of poly(2,3-dihydroxypropan-1-methacrylate acetonide- stat-butadiene), prepared by monomer starve-fed emulsion polymerization

Telechelic oligomers with dialdehyde end groups and 2,3-dihydroxypropan-1-methacrylate acetonide repeat units were prepared by the ozonolytic cleavage of poly(2,3-dihydroxypropan-1-methacrylate acetonide- stat-butadiene) copolymers. The latter were prepared by monomer starve-fed emulsion polymerization at elevated temperatures and at atmospheric pressure. In contrast to similar copolymerizations of methyl and butyl methacrylate these polymerizations generated a gel fraction as well as the usual soluble copolymer. However, following ozonolysis and work up with dimethyl sulphide the whole reaction mixture became soluble. Impurities derived from oligomers with carboxylic acid end groups were removed by preparative ion exchange with a strong base ion exchange resin. The oligomers have potential applications as components of amphiphilic networks.

The use of ion exchange resins for the treatment of cyanidation tailings part 1––process development of selective base metal elution

This work investigates the use of oxidative acid eluents for the elution of base metals from strong base ion exchange resins. Eluents composed of a mixture of H 2O 2 and H 2SO 4 were tested for eluting base metals from resins loaded with mixtures of base and precious metal cyanides. This process removed 100% of Cu and Zn loaded on the resin, without affecting the precious metal loading. It was found that copper could be removed separately from the other base metals. The elution technique was not effective for removing iron from the resin. Cyanide associated with base metals was recovered as NaCN. Some oxidation of cyanide was noticed, subject to the elution conditions. This oxidative acid elution process could be used in commercial operations for the selective elution of base metals from a strong base ion exchange resin bed operating in alternative adsorption/base metal elution cycles. Thus, virtually all metal cyanide species could be recovered from cyanide leached solutions or slurries to give relatively clean tailings without compromising precious metal recovery efficiency. The process also caters for cyanide recovery and recycling.

Selective elution of copper and iron cyanide complexes from ion exchange resins using saline solutions

Numerous reagents for the elution of metal cyanide complexes from ion exchange resins have been proposed previously. However, a simple and cost-effective elution procedure has not been developed that is able to selectively strip metal cyanide complexes from the resin. The results of the current study show that highly saline solutions can be used to selectively elute copper cyanide and iron cyanide complexes from a variety of anion exchange resins containing different quaternary ammonium functional groups. It was found that for most resins an elution efficiency of greater than 80% copper and 99% iron was achieved within 12 bed volumes (BV) of a concentrated KCl or MgCl 2 eluant containing 200 mg/L free cyanide. Gold cyanide and zinc cyanide complexes were not eluted from any of the resins studied. Poor elution of metal cyanide complexes was observed when a concentrated MgSO 4 eluant containing 200 mg/L free cyanide was used. It is proposed that the chloride anion successfully competes with copper cyanide and iron cyanide complexes for active sites on the resin. Furthermore, the stereochemistry and degree of hydration of these complexes facilitate their selective elution by highly saline solutions. It is proposed that a highly saline elution stage followed by a conventional thiocyanate or zinc cyanide elution stage for strong base resins will produce a very simple and efficient elution procedure for the selective recovery of gold cyanide from strong base ion exchange resins. Furthermore, the selective elution procedure allows for the recycling of cyanide that is bound to the copper and iron cyanide complexes.

Electrolytic desorption of silver from ion-exchange resins

Strong base ion-exchange resins Lewatit M 500 and Lewatit M 504 have steep ascending parts of isotherm curves in the range of low silver concentration in solution and can be used for silver extraction from plating rinsing effluents. Common elution methods are very inefficient for silver removal from strong base ion-exchange resins. Hence, the silver regeneration was performed by the electrolysis coupled elution process. During the process, the mass of silver deposited on the cathode and the I(t)–t curves were recorded. The electrolysis current was allowed to decrease to a value that corresponds to about 10% of the silver capacity. This was achieved from Lewatit M 500 at −1.14V electrolysis potential using the Pt cylinder gauze working electrode and at −1.30V using the Ni cylinder working electrode and from Lewatit M 504, at −1.10V using the Pt cylinder gauze working electrode and at −1.19V using the Ni cylinder electrode. During the first 3h of the process 60–80% of the silver can be removed. The desorption process depends on the hydrodynamic conditions provided between the resin beads and solution. It is possible to reuse Lewatit M 500 for the silver adsorption and desorption processes at least three times.

STATISTICAL THERMODYNAMIC MODEL FOR COMPETITIVE ION EXCHANGE

Most models for sorption equilibria in ion exchange systems give good piedictions under well-defined conditions, but fail to give accurate predictions in industrial streams owing to undefined composition or other non-ideal influences. To alleviate the shortcomings of these models, a n;w model based on statistical thermodynamic principles and particularly the Monte Carlo method is proposed. With the use of this new method classical non-ideal behavior such as lateral interactions, heterogeneous resin surfaces and selective sorption due to steric interactions can be modeled. All the parameters used have some physical meaning and describe only a single characteristic of the sorption system. This method was applied successfully to two example systems. The first system, the more classic ideal system containing H+, K+ and Na+, was modeled almost exactly. The second concerned the sorption of gold and zinc cyanide complexes onto a strong base ion exchange resin and proved to be difficult to model with existing met...

Cu II—diamine complex catalyzed hydrolysis of phosphate triesters adsorbed on strong-base ion exchange resins. 31P NMR relaxation measurements

The Cu II—diamine complexes, (bipy)CuSO 4 and (tmen)CuSO 4, catalyze the hydrolysis of p-nitrophenyl diphenyl phosphate (PNDP) adsorbed on a strong-base ion exchange resin. Turnover is observed. The major hydrolysis products are diphenyl phosphate, p-nitrophenyl phenyl phosphate, and the ethanolysis product ethyl diphenyl phosphate (EDPP) which are observed in similar amounts in both the presence and absence of the Cu II—diamine catalysts. The apparent bimolecular rate constants found for the (bipy) CuSO 4 and (tmen)CuSO 4 catalysts are 0.023 and 0.024 M −1 s −1, respectively. CuSO 4 is inactive as a catalyst. 31P MAS NMR relaxation measurements of the stable EDPP product reveal that the Cu II—diamine complexes greatly enhance T 1 relaxation, whereas CuSO 4 has only minimal effect. These results are consistent with the complexation of neutral phosphorus esters by the Cu II—diamine catalysts. 31P T 1 measurements of hydrolytically-stable dimethyl methylphosphonate (DMMP) in water solutions of Cu 2+, (tmen)Cu 2+, and Mn 2+ suggest that DMMP exchanges rapidly between inner-sphere and outer-sphere complexes in a nearly identical manner with each of these paramagnetic species.