Ion Exchange For Removal Research Articles

Rapid removal and catalytic decomposition of nitrate in anion-exchange resin containing gold nanoparticles toward purification of groundwater

We investigated the catalytic reduction of NO3– in various single-metal-introduced anion-exchange resins (AERs) in 1 bar H2 and observed that the reaction proceeded successfully. Among the metals considered in this study, Au was optimal in terms of catalytic activity and ease of catalyst preparation, whereas Ru exhibited the highest activity. The AER with Au (Au@AER) containing the optimal amount of Au (0.3mmol/g) decomposed 0.38mmol/g of NO3– primarily into N2O under optimized reaction conditions (80°C and 5 h). The decomposition amount corresponded to 41 % conversion. The incorporation of Au into the AER increased its ion-exchange capacity from 1.18 (pristine AER) to 1.46mmol/g (Au@AER); in contrast, the ion-exchange equilibrium constant decreased from 1.4 to 0.83 L mol−1 owing to the change in the structure of the anion-exchange sites in the AER. Au@AER was reusable for ion-exchange removal and catalytic decomposition of NO3– up to five times without performance degradation.

The effects of indigenous microorganisms and water treatment with ion exchange resin on Cu-Ni flotation performance

Mineral processing utilizes large amounts of water and aims to reduce water consumption by recirculation and closing the water loops. This results in accumulation of chemical and biological contaminants in process water that may have adverse outcomes on the process performance. To optimize water quality suitable for each process step and plant, knowledge of both chemical and biological effects are needed as well as techniques to best remove the contaminants. This study focused on the consequences of microorganisms, enriched from the actual process earlier, on the flotation performance in the multi-metal Kevitsa mine in Northern Finland and the applicability of ion exchange for the removal of dissolved sulfur species and microorganisms from water. The increase of microbial load from the original 106 to added 107 16S rRNA copies mL−1 affected positively the flotation selectivity, especially in the case of nickel. Two tested water types, process water (PW) and final tailings water (FT), behaved slightly differently. In the Cu flotation phase added microorganisms did not affect the Cu recovery of FT but decreased significantly the recovery of Cu in PW. With equal Cu grade, the recovery was as high as approximately 25 percentage points lower. However, added microorganisms in both water types decreased notably the recovery of Ni in Cu concentrate (18 to 37 %-points). At the same time the amount of Ni recovered in the Ni concentrate increased by 18 to 33 %-points with added microorganisms. Visually the froth layer was higher and more stable in the Ni flotation in experiments with added microorganisms compared to experiments without added microorganisms. The concentrations of dissolved sulfate and thiosulfate ions were low in the studied waters compared to operations treating massive sulfide ores and did not significantly affect the flotation performance. For this reason, the IX water treatment was not required for these ions. However, the IX treatment proved to be effective in removing both sulfur species and microorganisms. The use of dissolved air flotation (DAF) was a successful pretreatment for ion exchange in removal of microorganisms. However, microorganisms are not usually taken into consideration when process performance or water cleaning techniques are designed and optimization could result generally in even better outcome.

Design and Preparation of Magnetically-Oriented Poly(styr-co-MMA)-3MPS Capped Fe(ZnO) Hybrid Microspheres for Ion Exchange Removal of Toxic Pollutants from Wastewater

In this work, polymeric microspheres derived from polystyrene-co-methyl methacrylate embedded with magnetic ZnO nanoparticles (poly(styrene-co-MMA)-3MPS-Fe (ZnO)) were synthesized using the suspension polymerization method. The surfaces of polymeric Fe(ZnO) microspheres were improved by functionalization with amino and sulphonate groups. The physicochemical analysis indicated a large number of positively charged (anion exchange) groups (91 mmol/g) on the amine-modified polymeric microsphere (MFZPI) and a large number of negatively charged (cation exchange) groups (90 mmol/g) on the sulphonate-modified polymeric microsphere (SMFZPI)—revealing ambivalent character of obtained sorbent. The characterization of the synthesized compounds using various analytical techniques such as TGA, FTIR, XRD, SEM/EDX, UV-VIS and VSM indicated that synthesized microspheres were thermally stable, semi-crystalline in structure with hollow irregular morphology, optically active in UV region and slightly magnetic in nature. Due to the introduction of groups having ion exchange properties, these modified poly(styrene-co-MMA)-3MPS-Fe(ZnO) microspheres were used for the ion exchange sorptive removal of Cr(III) and fluorescein from aqueous matrix. The equilibrium sorption capacity of Cr(III) was 16.79 mg/g whereas of fluorescein was 12.03 mg/g under optimized conditions. Therefore, SMFZPI was found to be a promising sorbent for both cationic heavy metals and anionic dyes due to the presence of both acidic and basic groups. The mathematical modelling revealed that the sorption phenomenon followed pseudo-second-order kinetics with Freundlich equilibrium isotherm, indicating multilayer chemisorption of the pollutants on the synthesized ion exchange sorbents. This work establishes the utilization of polymeric magnetic ZnO-based ion exchange sorbents to effectively remove harmful toxins from wastewater.

Ion exchange removal and resin regeneration to treat per- and polyfluoroalkyl ether acids and other emerging PFAS in drinking water

Ion exchange (IX) is a promising technology to remove legacy anionic per- and polyfluoroalkyl substances (PFAS) from water. As increasing numbers of per- and polyfluoroalkyl ether acids (PFEA) and other emerging PFAS were detected in the environment, it is necessary to understand how well IX resins remove these emerging PFAS for drinking water treatment. In this study, nine commercially available IX resins were tested to treat a drinking water source spiked with 40 legacy and emerging PFAS at 600 ng/L, including PFEA, perfluoroalkyl carboxylic and sulfonic acids, fluorotelomer sulfonic acids, perfluoroalkane sulfonamides, perfluoroalkane sulfonamidoacetic acids, and zwitterionic species. With limited contact time (15 min), PFAS properties such as the fluorinated chain length, charge, and functional groups all affected PFAS adsorption to resins. However, the impact of PFAS properties on PFAS removal became less pronounced when the contact time increased beyond 2 h, while the resin polymer matrix became the critical factor for PFAS removal. All five tested polystyrene-divinylbenzene (PS-DVB) resins achieved more than 90% removal in 24 h of 35 PFAS compounds, while polymethacrylate and polyacrylic resins achieved >90% removal for less than half of the compounds. Regenerating PS-DVB resin was investigated using different salt species, regenerant pH, brine concentrations, and methanol contents. Sodium chloride and ammonium chloride were found the best brines for regenerating the tested resins. Increasing brine concentrations enhanced the regeneration efficiency, especially for short-chain PFAS. Using simple salt regenerants, up to 94% of selected short-chain PFAS was released from resins designed for general water treatment, but no meaningful regeneration was achieved for long-chain PFAS or PFAS-specific resins when the organic solvent content was less than 20%.

Single metal isotherm study of the ion exchange removal of Cu(II), Fe(II), Pb(II) and Zn(II) from synthetic acetic acid leachate

A large predicted increase in population growth and dwindling phosphate resources has led to sewage sludge being an attractive alternative to commercial fertilisers. Among other contaminants, heavy metals are a barrier to unrestricted use of sewage sludge or sewage sludge ash as a phosphate source. This study will focus on the equilibrium isotherm behaviours of Cu2+, Fe2+, Pb2+ and Zn2+ towards C107E, MTS9301 and TP214 resins within acetic acid media, fit to the two parameter Freundlich, Langmuir, Temkin and Dubinin-Radushkevich (D-R) isotherm models. C107E and MTS9301 were both found to have comparable monolayer capacities for Cu2+ and Fe2+ (5 ± 1 vs 4.3 ± 0.7 mmol·g−1 and 2.1 ± 0.8 vs 2.3 ± 0.8 mmol·g−1 for Cu2+ and Fe2+, respectively). The Freundlich model implied heterogeneous binding for Pb2+ and Zn2+ adsorption to C107E and MTS9301. The monolayer capacities of MTS9301 for lead and zinc were calculated as 2.1 ± 0.2 mmol·g−1 and 3 ± 1 mmol·g−1, respectively. MTS9301 returned larger D-R free energy values than C107E, with the largest difference being Zn2+, displaying energies of 14.0 and 5.5 kJ·mol−1, respectively. TP214 displayed the lowest capacity for metals with Fe2+, Pb2+ and Zn2+ returning D-R energy values closer to physisorption mechanisms (6.0 ± 0.5, 7.1 ± 0.4 and 7.8 ± 0.5 kJ·mol−1, respectively), with copper returning a D-R energy relating to chemisorption (17 ± 1 kJ·mol−1). Overall, it was observed that the similarity of the C107E functionality to the free acetate anion led to the highest level of hindrance, seconded by the interaction between Fe2+, Pb2+ and Zn2+ to TP214, while copper displayed strong interaction with TP214 and MTS9301 displayed little or no hindrance by the acetate complexes in solution, with solution phase complexes affecting the homogeneity of binding within any ion exchange reaction.

Ion exchange removal of Cu(II), Fe(II), Pb(II) and Zn(II) from acid extracted sewage sludge – Resin screening in weak acid media

A shortage of phosphate rock resources has led to a focus on the use of sewage sludge as a fertiliser. One factor preventing the unlimited application of sewage sludge in agriculture is the heavy metal content. This work looks at a process where weak acid leaching of sewage sludge would be coupled to ion exchange (IX) for heavy metal ion removal. IX offers an effective method for the recovery of these metals from a leachate. This study presents the pH performance of six selected IX resins in extracting Cu2+, Fe2+, Pb2+ and Zn2+ from acetic, lactic and citric acid media simulated weak acid leachate. Acetic acid media displayed limited suppression of metal extraction, whilst lactic and citric acid media rendered MTS9100 ineffective. Lactic acid media when combined with C107E resin allows for the targeted extraction of lead. Both MTS9570 and MTS9501 display high ferrous extraction in all media at all pH values, although citric acid hinders extraction by both resins at higher pH values. TP214 is selective for copper over all other metal ions in all weak acid media. MTS9301 is the most effective at extracting all metals from all media solutions, with separation of copper becoming more apparent when transitioning to citric acid.

Fixed Bed Modeling of Nonsteroidal Anti-Inflammatory Drug Removal by Ion-Exchange in Synthetic Urine: Mass Removal or Toxicity Reduction?

Ion-exchange removal of nonsteroidal anti-inflammatory drugs (NSAIDs) in synthetic urine can selectively remove pharmaceuticals with minimal coremoval of nutrients to enhance nutrient recovery efforts. However, the effect of endogenous metabolites in urine on ion-exchange removal, and the corresponding reduction in ecotoxicity potential of pharmaceuticals in treated urine entering the environment, is unknown. To assess treatment efficacy, this work paired predicted breakthrough curves determined by the homogeneous surface diffusion model to an in vitro bioassay to evaluate COX-1 inhibition. The presence of endogenous metabolites in urine significantly impacted pharmaceutical removal, by competing for ion-exchange sites on the resin and reducing the resin capacity for pharmaceuticals. This indicates ion-exchange would be ineffective at removing NSAIDs and other negatively charged compounds in urine. Due to hydrolysis of pharmaceutical metabolites back to the parent compound, treatment systems should be designed based on the ultimate pharmaceutical concentration in ureolyzed urine. Mass removal and COX-1 inhibition followed a nonlinear correlation and mixture toxicity followed the generalized concentration addition model. This work demonstrates the importance of evaluating removal of contaminants of emerging concern, such as pharmaceuticals, using a risk-based approach to ecotoxicity end points in conjunction with mass removal.

Issue Highlights

The Canadian Journal of Chemical EngineeringVolume 95, Issue 8 p. 1431-1431 Issue HighlightsFree Access Issue Highlights First published: 06 July 2017 https://doi.org/10.1002/cjce.22919AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat 1449 The Role of Hydrophobic Properties in Ion Exchange Removal of Organic Compounds from Water Sonia Rahmani and Madjid Mohseni The removal of organic compounds from water by ion exchange resins involves the contribution of various phenomena. This work studies the removal efficiency of three organic compounds which possess similar charged group but contain different non-polar moieties. The greater removal of compounds with more hydrophobic nature indicates the importance of solute-solvent interactions. Hydrophobic compounds also compete with inorganic anions present in the water matrix. The rejection of hydrophobic moieties from water and thus a favourable positive entropy change in the system by their removal is a crucial driver for the adsorption of organics onto the resin.1 1463 Prediction of Spout Diameter in Gas-Solid Spouted Beds Using Factorial Design of Experiments Approach with the Aid of Advanced Optical Fibre Probe Muthanna Al-Dahhan, Shreekanta Aradhya and Haidar Taofeeq The spout diameter is considered an important hydrodynamic parameter in the design and operation of gas-solid spouted beds. Therefore, the impact of five operating and design variables (solid density, static bed height, particle diameter, superficial gas velocity, and inlet diameter) on the spout diameter have been studied in the present work. The experimental measurements were carried out in a gas-solid spouted bed of 0.152 m inside diameter by the means of advanced gas-solid optical ibre probe technique. The factorial design of the experiments method was applied on the experimental results to evaluate the effect of these variables on the spout diameter.2 1605 Viscosity-Concentration Relationships for Nanodispersions Based on Glass Transition Point Rajinder Pal Using free volume arguments, a simple model is developed for the zero-shear relative viscosity of nanodispersions taking into consideration the solvation and aggregation of nanoparticles. The zero-shear relative viscosity data of 16 sets of nanodispersions are found to collapse onto a single curve when the data are plotted as relative viscosity versus volume fraction of solvated nanoparticles. The zero-shear viscosity of nanodispersions diverges at the glass transition volume fraction of solvated nanoparticles of about 0.58. Above the glass transition concentration of solvated nanoparticles, the correlation of relative viscosity of nanodispersions is not successful.3 References 1 S. Rahmani, M. Mohseni, Can. J. Chem. Eng. 2017, 95, 1449. 2 M. Al-Dahhan, S. Aradhya, H. Taofeeq, Can. J. Chem. Eng. 2017, 95, 1463. 3 R. Pal, Can. J. Chem. Eng. 2017, 95, 1605. Volume95, Issue8August 2017Pages 1431-1431 ReferencesRelatedInformation

Research processes of ion exchange removal phosphates

Phosphorus is one of the products of metabolism or degradation of microbial organisms, but its excess leads to accelerated eutrophication. The primary cause of eutrophication – is excessive concentration of nutrients in the water, including phosphates. Among the existing methods of water purification from phosphates ion exchange is the most effective and cheap one. This method is advantageous because of the possibility of processing of the regeneration solutions to produce liquid fertilizers or other useful products. Highly basic anionite AB-17-8 and low basic anionite Dowex Marathon WBA are used as the ion exchange materials. Distilled and tap water close to the characteristics of wastewater of Bortnichy aeration station was used as the medium . It was shown that the exchange capacity of anionite Dowex Marathon WBA for phosphates is low and its use for the removal of phosphates is inappropriate. The highly basic anionite AB-17-8 in chloride and in alkaline form provides effective removal of phosphates from model solutions. The influence of competing compounds of sulfate and chloride in tap water on efficiency of phosphate anions extraction was studied. Regeneration processes were investigated using solutions of sodium or ammonium chlorides in concentration of 10-15%. Method for the removal of interfering compounds of sulfates from regeneration solutions in the form of gypsum is proposed, which will allow re-use of these solutions for the regeneration of the anion exchanger.

The role of hydrophobic properties in ion exchange removal of organic compounds from water

The removal of organic compounds by ion exchange resins is a complex process due to the involvement of several interacting phenomena during the course of removal. The objective of this research is to clarify the contribution of these interactions to the removal of different organic compounds under various solution conditions. This study investigates the sorption of three ionizable organic compounds, which are identical in terms of ionic charges and different in their non‐polar moieties, in order to better evaluate the contribution of solute‐solvent interactions to the affinity of these compounds for ion exchange. The higher uptake of hydrophobic compounds and lower competition effect from inorganic anions on the removal of these compounds provide evidence for the importance of the hydrophobic effect. The hydrophobic characteristics of organic compounds and the favourable entropy change that they impose during de‐solvation contribute greatly to the ion exchange selectivity of these compounds. Furthermore, increasing the ionic strength of solution by adding high charge density anions, such as sulphate, to the water diminishes the contribution of electrostatic interaction, and hence the potential physical adsorption between resin and organic molecule predominates the removal mechanism. No change in removal mechanism is observed in the presence of inorganic anions with low charge density such as nitrate.

Rapid ion-exchange matrix removal for a decrease of detection limits in the analysis of salt-rich reservoir waters for fluorobenzoic acids by liquid chromatography coupled with tandem mass spectrometry

A matrix removal procedure with ion-exchange resin prior to analysis for 18 fluorinated benzoic acids (FBAs) tracers in saline (>25% salt) reservoir water was optimized. The elimination of >98% of salt and the simultaneous matrix sample cleanup allowed the direct analysis using the supernatant by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This resulted in a gain in detection limits for most of the tracers in comparison with the reference method (direct analysis after minimum required dilution). The limits of detection (LODs) were in the range of 0.01–0.15 ng/ml and compared to other studies the developed method provided comparable limits of detection and advantage of simplified and shorter sample preparation. The presented method offers a considerable gain in simplicity and analysis time. Recoveries for all the tracers reached 80–100%, except for 2-FBA and 2,6-dFBA for which they were ca. 60%. The low recoveries were corrected by the use of five isotopically labeled internal standards. The method was validated by the analysis of spiked samples and by an independent comparison of the results with those obtained by solid-phase extraction LC-MS/MS method.

Cation resin fixed-bed column for the recovery of valuable THAM reagent from the wastewater

Abstract Two commercial available cation resins, i.e. Amberlite IR-120 and Dowex HCR-W2, were tested as ion exchange adsorbents to investigate their isotherms, kinetics, breakthrough characteristics and regeneration on removal and recovery of tetra-methyl ammonium hydroxide (TMAH) from wastewater. Batch and column experiments were investigated to obtain experimental data for theoretical modelling and verify the column performance of the ion exchange process. The Langmuir isotherm represents better equilibrium behavior of both resins on TMAH uptake. The ion exchange kinetics follows the pseudo second order rate law also for both resins. Furthermore, breakthrough characteristics study shows the breakthrough curves follow the Thomas model and Yoon–Nelson model very well. The recovery efficiencies of TMAH were obtained as 99.6 and 98.0% from wastewater by ion exchange resin column by using 9 N HCl regeneration for Amberlite IR-120 and Dowex HCR-W2 resins, respectively. The comparative study on TMAH ion exchange removal by Amberlite IR-120 and Dowex HCR-W2 resins in fixed bed column suggested that Dowex HCR-W2 demonstrates higher ion exchange capacity than that of Amberlite IR-120 resin.

Application of mathematical models for ion-exchange removal of calcium ions from potassium chromate solutions by Amberlite IRC 748 resin in a continuous fixed bed column

This study investigated the performance of Amberlite IRC 748 resin in removing calcium ions from highly concentrated potassium chromate solution in a fixed bed column. The exchange capacity increased with initial calcium ion concentration and bed height but decreased as flow rate increased. Four different kinetic models, specifically the bed depth service time (BDST), mass transfer, Thomas, and Yoon–Nelson models, were applied to the experimental data to predict the breakthrough curves and determine the column parameters. The BDST model was extended to the prediction of service times of columns operated at different flow rates and influent concentrations; while the experimental and theoretical data points followed a similar trend, they deviated slightly from each other. The Thomas and Yoon–Nelson model predictions were in very good agreement with the experimental results for all the process parameters studied, indicating that they are suitable for use with these kinds of columns.

Ion-Exchange Removal of Fe(III) and Mg(II) in the Analysis of Rare Earth Elements in Rocks by Inductively Coupled Plasma Mass Spectrometry

Tiron has been proposed for the removal of Fe (III) and Mg (II) ions from the test solution by ion exchange in the REE trace analysis in rocks by ICP-MS. The conditions for Fe (III) isolation on a column with anion-exchange resin АВ-17-8,Cl– and for Mg (II) on a column with cation-exchange resin Purolite С100 have been found. The concentration of Fe (III) is reduced up to 10 times, and Mg (II) – more than 100 times. Correction factors have been used in order to eliminate the systematic error in the determination of REE due to their partial sorption on the anion-exchange resin in the form of complexes with Tiron. The correctness and accuracy of the developed sample preparation method and of the correction factors have been confirmed in the analysis of standard samples base on natural geochemical objects.

Ion-exchange selectivity of diclofenac, ibuprofen, ketoprofen, and naproxen in ureolyzed human urine

This research advances the knowledge of ion-exchange of four non-steroidal anti-inflammatory drugs (NSAIDs) – diclofenac (DCF), ibuprofen (IBP), ketoprofen (KTP), and naproxen (NPX) – and one analgesic drug–paracetamol (PCM) – by strong-base anion exchange resin (AER) in synthetic ureolyzed urine. Freundlich, Langmuir, Dubinin–Astakhov, and Dubinin–Radushkevich isotherm models were fit to experimental equilibrium data using nonlinear least squares method. Favorable ion-exchange was observed for DCF, KTP, and NPX, whereas unfavorable ion-exchange was observed for IBP and PCM. The ion-exchange selectivity of the AER was enhanced by van der Waals interactions between the pharmaceutical and AER as well as the hydrophobicity of the pharmaceutical. For instance, the high selectivity of the AER for DCF was due to the combination of Coulombic interactions between quaternary ammonium functional group of resin and carboxylate functional group of DCF, van der Waals interactions between polystyrene resin matrix and benzene rings of DCF, and possibly hydrogen bonding between dimethylethanol amine functional group side chain and carboxylate and amine functional groups of DCF. Based on analysis of covariance, the presence of multiple pharmaceuticals did not have a significant effect on ion-exchange removal when the NSAIDs were combined in solution. The AER reached saturation of the pharmaceuticals in a continuous-flow column at varying bed volumes following a decreasing order of DCF > NPX ≈ KTP > IBP. Complete regeneration of the column was achieved using a 5% (m/m) NaCl, equal-volume water–methanol solution. Results from multiple treatment and regeneration cycles provide insight into the practical application of pharmaceutical ion-exchange in ureolyzed urine using AER.

Ion Exchange for Removal of Chloride from Recycled Water

Ion Exchange for Removal of Chloride from Recycled Water

Applications versus properties of Mg–Al layered double hydroxides provided by their syntheses methods: Alkoxide and alkoxide-free sol–gel syntheses and hydrothermal precipitation

A tremendous number of studies have examined layered double hydroxides (LDH) for their technological applications in the ion exchange removal of toxic ions, recovery of valuable substances, catalysis, CO2 capture, as a layered host for storage/delivery of biologically active molecules, additives to plastics and building materials, and other functions. Numerous publications always conclude that the materials (prepared, as a rule, using the oldest synthesis method) are very promising for each investigated application; however, the main chemical industries producing these materials advertise them mainly (or only) as plastic additives. The authors performed extensive research using many of the appropriate methods to compare the structure, surface and adsorptive properties of three Mg–Al LHDs produced by advanced synthesis methods. One industrial sample (by Sasol, Germany) prepared by the alkoxide sol–gel method and two novel Mg–Al LDHs synthesised in-house by alkoxide-free sol–gel and hydrothermal precipitation approaches were investigated. Reasons for the very different adsorptive selectivity of the three LDHs towards arsenate, selenate, phosphate, arsenite and selenite have been provided, highlighting the role of speciation of the interlayer carbonate, aluminium, magnesium, interlayer hydration and moisture content in the adsorptive selectivity towards each toxic anion. This work is the first report presenting the regularities of the LDHs structure, surface and anion exchange properties as a function of their syntheses method. It establishes the links to potential technological applications of each investigated LDH and explains the necessary properties required to make the technological application cost-effective and efficient. The paper might accelerate industrial applications of these advanced materials.

Determination of lead separated selectively with ion exchange method from solution onto BCW in Sirnak, East Anatolia of Turkey

There are approximately 82 million of tons asphaltites reserves in Şirnak, East Anatolia of Turkey. The present study was investigated to employ ashes of Sırnak BCW (burned coal waste) as an ion exchange in removal of important toxic metal, Lead (Pb), in high yields by adsorption. The ion exchange characteristics of lead onto BCW from aqueous solution were investigated with respect to the changes in pH of solution, adsorbent dosage, initial metal ion concentration, contact time and temperature of solution. For the adsorption of lead, the Langmuir isotherm model fitted to equilibrium data better than the Freundlich isotherm model. Thermodynamic functions, the change of free energy (ΔG°), enthalpy (Δ H°) and entropy (Δ S°) of adsorption were also calculated for lead. These parameters showed that the adsorption was feasible, spontaneous and exothermic at 293–333 K. Experimental data were also evaluated in terms of kinetic characteristics of adsorption. The batch kinetic data were correlated to the pseudo-first order and pseudo-second order models. The data fitted better to the pseudo-second order equation. The activation energy of systems was determined. Experimental data have shown that BCW that was used in unmodified form; as low cost, readily available ion exchange; can be used for removal of lead from industrial waste waters. Analysis was determined using Flame Atomic Absorption Spectrometry (FAAS).

A New Approach to Catalytic Degradation of Dimethyl Phthlate by a Macroporous OH-Type Strongly Basic Anion Exchange Resin

In the present study, a novel approach was developed to remove dimethyl phthalate (DMP), a representative phthalic acid ester (PAE) pollutant, from an aqueous solution using a macroporous OH-type strong base anion exchange resin D201-OH. As compared to the traditional catalyst aqueous NaOH, D201-OH displayed much higher catalytic efficiency for DMP hydrolytic degradation. Almost 100% of DMP was hydrolyzed to far less toxic phthalic acid (PA) in the presence of D201-OH, while only about 29% of DMP was converted to PA in the presence of NaOH under the identical amount of hydroxyl anions in the reaction system. More attractively, the hydrolysis product PA also can be simultaneously removed by the solid basic polymer D201-OH through a preferable anion exchange process, while NaOH induced hydrolysis products were still left in solution. The underlying mechanism for the hydrolytic degradation and simultaneous ion exchange removal process was proposed. Fixed-bed column hydrolytic degradation and ion exchange removal tests indicate that DMP can be completely converted to PA and subsequently removed from water without any further process, with pH values of the effluent being around 6 constantly. The exhausted D201-OH was amenable to an efficient regeneration by 3 bed volumes (BV) of NaOH solution (2 mol/L) for repeated use without any efficiency loss. The results reported herein indicated that D201-OH-induced catalytic degradation and removal is a promising approach for PAEs treatment in waters.

Removal, preconcentration and determination of trace heavy metal ions in water samples by AAS via chemically modified silica gel N-(1-carboxy-6-hydroxy) benzylidenepropylamine ion exchanger

The use of chemically modified silica gel N-(1-carboxy-6-hydroxy) benzylidenepropylamine (SiG-CHBPA), ion exchanger for removal and preconcentration of Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb in natural water samples collected from River Nile, Mediterranean Sea and other locations followed by their consecutive AAS determination was described. The effects on the percentage of recovered metal ions including mass change of ion exchanger, stirring time, pH of sample solutions and eluent concentration were studied. The distribution coefficient Kd, mlg−1 and the percentage concentration of the studied metal ions on the ion exchanger at equilibrium, CM,eqm ,% (Recovery, %) were studied as a function of experimental parameters. The logarithmic values of the distribution coefficients, log Kd are 3–6.3. The interfering effects of some foreign ions on the removal, preconcentration and determination of the investigated metal ions were described. The metal-chelates formed between the ion exchanger and the studied metal ions were characterized by IR (absorption and reflectance), UV spectrometry, potentiometric titration and thermal analysis (TG and DTG). The reliability of the present method was confirmed by the comparison with a standard solvent extraction method. The present method is simple and rapidly applicable for the determination of the studied metal ions, ngml−1 in different natural water samples.