Adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid–nitric acid aqueous solution by strong acid cation resin

The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.

Development of Prolonged Release Microspheres of Metformin Hydrochloride Using Ion Exchange Resins

Aim To prepare the prolonged-released microspheres of mefformin hydrochloride. Methods Ion-exchange resin-drug mefformin hydrochloride complexes were prepared as core materials, and followed by coating using ethylcellulose （EC） by the emulsion solvent diffusion technique. The release rate of mefformin from the microcapsules was highly dependent on the encapsulating formulation, thus being used as an index for formulation screening. Orthogonal experiments were performed to optimize the coating formulation. Results The final chosen formulation for coating of mefformin microcapsules were as follows： （ 1 ） the ratio of EC （20cps） to EC （45cps） was 50：50; （2） the ratio of plasticizer to coating materials was 20% ;and （3） the ratio of resin-mefformin complexes to coating materials was 5 ： 1. Conclusion The prolonged release microspheres of mefformin hydrochloride were successfully prepared.

Preparation and quality assessment of high-purity ginseng total saponins by ion exchange resin combined with macroporous adsorption resin separation

AIM： To prepare high-purity ginseng total saponins from a water decoction of Chinese ginseng root.METHOD： Total saponins were efficiently purified by dynamic anion-cation exchange following the removal of hydrophilic impurities by macroporous resin D101. For quality control, ultrahigh-performance liquid chromatography with a charged aerosol detector （CAD） was applied to quantify marker components. The total saponin content was estimated by a colorimetric method using a vanillin-vitriol system and CAD response. RESULTS： D201, which consisted of a cross-linked polystyrene matrix and -]N＋（CI-13）3 functional groups, was the best of the four anion exchange resins tested. However, no significant difference in cation exchange ability was observed between D001 （strong acid） and D 113 （weak acid）, although they have different functional groups and matrices. After purification in combination with D101, D201, and D 113, the estimated contents of total saponins were 107% and 90% according to the colorimetric method and CAD response, respectively. The total amount of representative ginsenosides Re, Rd, Rgl, and compound K was approximately 22% based on ultrahigh-performance liquid chromatography-CAD quantitative analysis. CONCLUSION： These findings suggest that an ion exchange resin, combined with macroporous adsorption resin separation, is a promising and feasible purification procedure for neutral natural polar components.

Direct extraction of Mo(VI) from acidic leach solution of molybdenite ore by ion exchange resin:Batch and column adsorption studies

The adsorption behavior of ion exchange resin D301 in the extraction of hexavalent molybdenum from high acidic leach solution was investigated. SEM, EDS and Raman spectra analyses were applied to studying the adsorption capacity, reaction kinetics and possible adsorption mechanism in detail. Results showed that the adsorption capacity of D301 resin for molybdenum from high acidic leach solution was up to 463.63 mg/g. Results of the kinetic analysis indicated that the adsorption process was controlled by the particle diffusion with the activation energy 25.47 k J/mol（0.9-1.2 mm） and 20.38 k J/mol（0.6-0.9 mm）. Furthermore, the molybdenum loaded on the resin could be eluted by using 2 mol/L ammonia hydroxide solution. Besides, dynamic continuous column experiments verified direct extraction of molybdenum from acidic leach solutions by ion exchange resin D301 and the upstream flow improved dynamic continuous absorption.

Study on the influence of humic acid of different molecular weight on basic ion exchange resin's adsorption capacity

In this paper, humic acid （HA） was ultra-filtered into different molecular weight sections and was characterized by multielement analysis, UV254/TOC, FT-IR and three-dimensional fluorescence spectrometric. Since humic acids of different molecular weights have different hydrophilic and molecular size, the maximum adsorption capacity of basic ion exchange resins appears on the humic acid whose molecular weight ranges from 6000 to 10,000 Da.

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, Langnluir-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 threemodels with reasonable errors.

Combination of chlorine and magnetic ion exchange resin for drinking water treatment of algae

The effectiveness of a magnetic ion exchange resin （MIEX） for the treatment of Hongze Lake water in China was evaluated, The kinetics of natural organic matter （NOM） removal at various MIEX doses and contact time, multiple-loading experiments, impacts of MIEX prior to coagulation on coagulant demands and the effectiveness of combination of MIEX, pre-chlorination and coagulation were investigated. Kinetic experimental results show that more than 80% UV254 and 67% dissolved organic carbon （DOC） from raw water can be removed by the use of MIEX alone. 94% sulfate, 69% nitrate and 98% bromide removals are obtained after the first use of MIEX in multiple-loading experiments. It is suggested that MIEX can be loaded up to 1 250 bed volume （BV, volume ratio of tested water to resin） or more without saturation when regarding organics removal as a target. MIEX can remove organics to a greater extend than coagulation and lower the coagulant demand when combining with coagulation. Chlorination experimental results show that MIEX can remove 57% chlorine demand and 77% trihalomethane formation potential （THMFP） for raw water. Pre-chlorination followed by MIEX and coagulation can give additional organic and THMFP removals. The results suggest that MIEX provides a new method to solve thc problem algae reproduction.

Taste masking of ciprofloxacin by ion-exchange resin and sustain release at gastric-intestinal through interpenetrating polymer network

The aim of the study was to taste mask ciprofloxacin(CP)by using ion-exchange resins(IERs)followed by sustain release of CP by forming interpenetrating polymer network(IPN).IERs based on the copolymerization of acrylic acid with different cross linking agents were synthesised.Drug-resin complexes(DRCs)with three different ratios of drug to IERs(1:1,1:2,1:4)were prepared&evaluated for taste masking by following in vivo and in vitro methods.Human volunteers graded ADC 1:4,acrylic acid-divinyl benzene(ADC-3)resin as tasteless.Characterization studies such as FTIR,SEM,DSC,P-XRD differentiated ADC 1:4,from physical mixture(PM 1:4)and confirmed the formation of complex.In vitro drug release of ADC 1:4 showed complete release of CP within 60 min at simulated gastric fluid(SGF)i.e.pH 1.2.IPN beads were prepared with ADC 1:4 by using sodium alginate(AL)and sodium alginate-chitosan(AL-CS)for sustain release of CP at SGF pH and followed by simulated intestinal fluid(SIF i.e.pH 7.4).FTIR spectra confirmed the formation of IPN beads.The release of CP was sustain at SGF pH(<20%)whereas in SIF media it was more(>75%).The kinetic model of IPN beads showed the release of CP was non-Fickian diffusion type.

A new configuration of membrane stack for retrieval of nickel absorbed in resins

A new configuration integrated ion exchange effect with both electro-migration and electrochemical reaction in a single cell was developed to effectively retrieve metal ions from simulated wastewater using ion exchange resins without additive chemicals. By simply assembling cation exchange resins and anion exchange resins separated by homogeneous membranes, we found that the system will always be acidic in the concentrate compartment so that ion exchange resins could be in-situ regenerated without hydroxide precipitation. Such a realizable design will be really suitable for wastewater purification.

Reaction kinetics for the heterogeneously resin-catalyzed and homogeneously self-catalyzed esterification of thioglycolic acid with 2-ethyl-1-hexanol

Producing 2-ethyl-1-hexyl thioglycolate(ETE)via esterification reaction with thioglycolic acid(TGA)aqueous solution as raw material by reactive-separation coupling technology is a promising process intensification method.To choose suitable reactive-separation coupling strategy,the kinetic studies of the esterification of TGA with 2-ethyl-1-hexanol(EHL)were carried out in a batch system.The commercial ion exchange resin was employed as an eco-friendly catalyst.The effects of temperature,catalyst concentration and molar ratio were determined.It was interesting to observe that the equilibrium conversion of TGA increased with the increase of catalyst mass fraction due to the adsorption of product water onto resin surface.The activity-based pseudo-homogeneous(PH),Eley-Rideal(ER)and Langmuir-Hinshelwood-Ho ugen-Watson(LHHW)models were used to fit the kinetics data of the resin-catalyzed reaction.The models of ER and LHHW performed better than the PH model.The kinetics of the TGA-self-catalyzed reaction was also determined.An activity-based homogeneous kinetics model could well describe this self-catalyzed reaction.These results would be meaningful to the selection and design of an appropriate reactionseparation strategy for the production of ETE,to realize the process intensification.

Optimizing the Synthesis of Ethyl tert-Butyl Ether in Continuous Catalytic Distillation Column Using New Ion Exchange Resin Catalyst

Liquid phase synthesis of one of the important fuel oxygenate, ethyl tert-butyl ether （ETBE）, from etha-nol and tert-butyl alcohol （TBA） has been studied in catalytic distillation column （CDC） using ion exchange resin catalyst CT-145H. A packed CDC of 1.2 m height and 50 mm diameter with indigenously developed reactive sec-tion packing was used to generate experimental data. Effect of different key variables on product purity in distillate, was investigated to find the optimum operating conditions for ETBE synthesis. The optimum conditions for 0.2 kg·s-1 of ethanol feed were found：reboiler duty of 375 W, molar feed ratio of 1︰1.3 of reactants, and reflux ratio of 7. Concentration profiles for each component along each column section at optimum conditions were also drawn. Neither output nor input multiplicity was observed at experimental conditions.

17α-Ethinylestradiol removal from water by magnetic ion exchange resin

Magnetic ion exchange(MIEX) resins have received considerable attention in drinking water treatment due to their fast and efficient removal of dissolved organic carbon(DOC). Two types of mechanisms, i.e., ion exchange,reversible and irreversible adsorption, may occur during pollutants removal by MIEX. This work examined the removal mechanism of 17α-Ethinylestradiol(EE2) by MIEX. As one of typical estrogen micro-pollutants,EE2 existed as neutral molecule in natural water, and its charge density was close to zero [(0.00000219 ±0.00000015) meq·(μg EE2)^(-1)] based on the potentiometric titration method. However, the removal of EE2 by MIEX was much higher than that of other micro-pollutants previously reported. Multi-cycle adsorptionregeneration experiments and ion exchange stoichiometry analysis were conducted to elucidate the removal mechanism of EE2 by MIEX resin. The results suggested that the main removal mechanism of EE2 by MIEX was ion exchange instead of reversible micro-pore adsorption. The experimental analysis based on Donnan theory indicated that the internal micro-environment of resin beads was alkaline, in the alkaline environment EE2 would be ionized into negatively charged groups. As a result, ion exchange reaction occurred inside the pore of MIEX resin, and the removal process of EE2 by MIEX was dominated by the ion exchange reaction.

ADSORPTION OF HUMIC SUBSTANCES BY MACRO WEAKLY BASIC IONEXCHANGE RESIN AND THEIR EFFECTS ON REMOVAL OF Cu^(2+) AND Pb^(2+)

Adsorption of humic, tannic and gallic acids by a macro weakly basic ion-exchange resin JN-01 was studied. The adsorption capacity of this resin for gallic and tannic acids is much higher than that for humic acid, which can be explained on the basis of both their molecular size and ionization degree. Furthermore, humic acid is separated into different components with molecular weight in the range from 2000 Da to 100000 Da by ultra-filter, and their adsorption isotherms on resin JN-01 indicate that humic acid＇s molecular weight is an important factor which makes significant influence on adsorption. Finally, changes in the amount of Cu^2＋ and Pb^2＋ adsorbed on resin JN-01 as a function of the concentration of each of these three acids were studied. A large increase in the heavy metal ions uptake is observed in the presence of humic substance, such advantages are due to the interactions between the heavy metal ions and the unbound functional groups of the adsorbed organic acids.

Thermal Analysis and Immobilisation of Spent Ion Exchange Resin in Borosilicate Glass

The underground disposal of waste arising from the nuclear industry needs constant evaluation in order to improve upon it through minimizing the volume and cost by reducing the amount of glass used without compromising the safety of any leakage from the radioactive waste form. The immobilization of the spent resin (NRW-40) in borosilicate glass was investigated to meet the acceptance criteria for disposal of nuclear waste. The organic mixed bed resin in granular form was used as a waste target. The analysis of surrogate resin doped with radioactive and non-radioactive cesium (Cs) and cobalt (Co) was carried out to investigate their thermal and chemical properties and their compatibility with an alkaline borosilicate glass. The thermal analysis indicates that the structural damage caused by 1 mSv gamma radiation to the radioactive resin has altered its properties in comparison with the non-radioactive resin, same amount of cesium (8.88 wt%) and cobalt (1.88 wt%) were used in both resins. The immobilization of residue shows that the excess sulfur in the residue caused phase crystallization in the final glass matrix. It was found that the volatilization of Cs-137 and Co-60 from the successful radioactive resin-glass matrix (HG-3-IER-500) were more than that in the non-radioactive resin-glass matrix (HG-3-IEX-500). The study demonstrates comprehensive experimental and analytical works and shows that it is possible to minimise the volume of the waste while keeping the required safety levels, however further research needs to be carried out in this area.

Behaviour of radioactive iodide and bromide ions from aqueous solution on ion exchange resins Amberlite IRA-400

The ion exchange resin Amberlite IRA-400 in iodide and bromide form where equilibrated separately with the respective labeled iodide and bromide ion solution of different concen-trations varying from 0.005M to 0.100M in the temperature range of 32.0 oC to 48.0 oC. The dis-tribution coefficient Kd values calculated for iodide and bromide ion exchange increases with rise in ionic concentration of the external solution, however with rise in temperature the Kd values calculated where found to decrease. Also the Kd values calculated where higher for iodide exchange than bromide exchange. Among the different alternative techniques available for obtaining the Kd values, the radio-active tracer technique used in the present ex-perimental work offers high detection sensitivity. It is expected that the distribution coefficient data obtained from such experimental work will significant in environmental impact assessment on the disposal of radioactive waste.

ELECTRIC REGENERATION METHOD OF IONEXCHANGE RESIN IN THE MIXED BED

In this paper the self-regeneration process of the mixed resins consisting of cationand anion ion exchangers in the electrolialyser of the packed bed is analyzed and anelectric regeneration method is put forward to supply the desalinated water by mixedbed The electric regeneration technology is a new one used for regeneration of theexhausted ion exchangers in the mixed bed instead of the traditional regeneratingprocess by using acid and abc liquor Electric energy is consumed to regenerat theion exchangers loaded by salts from water treatment without any chemicals- acid alkali. The advantage of the electric regeneration process edibited convenientoperation, no discharge any waste, and therefore no Polluted to the recehang waterbode and the environmental ground

ADSORPTION STUDIES OF TANNIC ACID BY COMMERCIAL ESTER RESIN XAD-7

Tannic acid and its related compounds are known as refractory organic pollutants, and it can create serious problems for the environment. The adsorption and desorption studies of tannic acid on commercial resins XAD-7 and D-201 are performed, and all data indicates resin XAD-7 can be used as an effective adsorbent for removing tannic acid during water/wastewater treatment. Furthermore, adsorption thermodynamics studies indicate different adsorption mechanisms for TA on XAD-7 and D-201. FT-IR and solid state 13C-NMR spectroscopy are used to explain the adsorption force between XAD-7 and TA. It suggests that hydrogen bonding is the main adsorption force for TA. Finally, XAD-7＇s adsorption capacity in the presence of different metal ions is investigated, which indicates that heavy metal ions in solutions can decrease the adsorption capacity for TA on ester resin XAD-7.

Adsorption properties of Ag(Ⅰ),Au(Ⅲ),Pd(Ⅱ)and Pt(Ⅳ)ions on commercial 717 anion-exchange resin

The adsorption properties of the four precious metal ions(Ag(Ⅰ),Au(Ⅲ),Pd(Ⅱ)and Pt(Ⅳ))on the commercial Cl--form 717 strongly basic anion-exchange resin were studied in detail.The effects of the contact time,solution acidity,and concentrations of Cl - and Pb 2+ ions on the adsorption properties were studied by the batch method.Then,the column method was conducted under the optimized adsorption conditions(pH=3.0).The effects of the sample loading flow rate and the length-to-diameter ratios of the columns were investigated.The precious metal ions adsorbed could not be eluted completely after the saturated adsorption because the precious metal ions were found to be reduced to their metallic states during the adsorption process.So,it is recommended that the commercial Cl--form 717 strongly basic anion-exchange resin should be decomposed directly to recovery the precious metals after the saturated adsorption.

Complexation Between Borate ion and Hydroxyl Groups of Phenol-Formaldehyde Resol Resin

The complexation reaction between borate ions and phenol-formaldehyde resol resin in aqueous solution was studied by pH measurement, small model molecules and infrared spectroscopy. The results show that the complexation can proceed completely and rapidly at room temperature. Borate ion attacks phenol hydroxyl groups and adjacent position hydroxymethyl groups on the phenol ring of the resin, and forms the coordinate bond between boron atom in borate ion and oxygen atom in the hydroxyl groups. The complexation is a quantitative reaction. The complex is a six member ring containing two oxygens and one boron. The complexation can release hydrogen ions resulting in the decreasing pH in the resin solution.

Chemistry of marine resources－XIX． The molecule design and synthesis of crow－link type Alkyd resin and its enrichment behaviour For potassium ion in sea water

This paper first presents the molecule design and synthesis of crown-link type alkyd resin, and itsenrichment behaviour for potassium ion in low concentration solution and sea water. On the basis of some theoryconcepts of Host-Guest chemistry developed in recent years, we have designed and synthesized a new polymerenrichment agent of crow-link resin for potassium ion, i. e., polymacrocyclic ether bislactone of diethylene glycolpyromyllitic acid (briefly called crown-link type alkyd resin or PBL resin ). The yield was about 97. 4%, almost quantitatively. The enrichment behaviour of this thermosetting resin for potassium ion in low concentration solution, underground brine from the coastal area of the Laizhou Bay and natural sea water has been studied. Experimentalresults shows that PBL-resin is suitable for the enrichment of low concentration potassium ion from natural seawater and underground brine of Laizhou Bay. The enrichment capacity of potassium ion reached up to 22. 5×10-3 and 36. 5×10--3 respectively.According to the experimental results, a mechanism which causes the uptake of potassium ion is suggestedand a new opinion about the'aperture.suitability theory'of rich-oxygen macrocyclic polymer to coordinate potassium ion selectively is put forward.