Weak Base Anion Exchange Resin Research Articles

Preparation and characterization of taste masked valsartan by ion-exchange resin approach

The bitter taste is one of the most important drug formulation problems. The unpleasant taste leads to noncompliance, which consequently decreases the therapeutic efficacy of the drug. Therefore, masking of bitter taste is very important in drug formulation. In this study an antihypertensive drug, valsartan, which is a weak acid with bitter taste, was used as a model drug to mask its taste with dowex2 (weak base anion exchange resin). The taste masking of a drug using ion exchange resin basically depends on the complex formation between the drug and a specific type of resin. Complex formation under various preparation conditions including; the ratio of drug to resin, mixing time, the pH of the processing medium and the concentration of valsartan was investigated in this study. Optimum conditions for complex formation and maximum drug load were obtained at a drug-resin ratio 1:8, mixing time 4 hours, pH 6.8, temperature 50º C and drug concentration 0.02% w/v. The drug resin ate complex was evaluated for the drug content, taste, drug release and molecular properties. The resinate formation was confirmed using different analytical techniques like thermal analysis using differential scanning calorimetry (DSC), spectroscopic method like Fourier transform infrared spectroscopy (FTIR) and by X-ray powder diffraction analysis (XRPD).

Research on adsorption of Cr(Ⅵ) by Poly-epichlorohydrin-dimethylamine (EPIDMA) modified weakly basic anion exchange resin D301

A novel composite, EPIDMA/D301, with high adsorption capacity and particular affinity toward Cr(Ⅵ) was well prepared utilizing cationic polyelectrolyte poly-epichlorohydrin-dimethylamine (EPIDMA) impregnated in the networking pores of the styrene macroporous weak basic anion exchange resin D301. The physicochemical characteristics of EPIDMA/D301 were characterized by the Brunauer-Emmett-Teller (BET), zeta potential, FTIR, SEM-Mapping and XPS. The adsorption properties were researched via the influence of the concentration of EPIDMA, adsorbent dose, pH, the initial concentration of Cr(Ⅵ) solution, contact time and temperature. Results presented that the weakly basic anion exchange resin supported cationic polymer showed the excellent potential of removing Cr(VI) ions primarily due to the nonspecific Cr(VI) adsorption resulted from the polymeric host D301, the electrostatic attraction of amino groups fixed on the D301 matrix and the embedded EPIDMA with Cr(VI) ions and the ion exchange by the displacement of Cl- mainly derived from EPIDMA with Cr(VI) ions. The kinetic data were best fitted by the pseudo-second-order kinetic model. The batch equilibrium data followed Langmuir isotherm model well with the maximum adsorption capacity of 194 mg g−1 at 25 °C, which demonstrated that the styrene anion exchange resin modified with EPIDMA might be an efficient approach to eliminate potentially toxic metals.

Preparation and characterization of taste masked valsartan by ion-exchange resin approach

The bitter taste is one of the most important drug formulation problems. The unpleasant taste leads to noncompliance, which consequently decreases the therapeutic efficacy of the drug. Therefore, masking of bitter taste is very important in drug formulation. In this study an antihypertensive drug, valsartan, which is a weak acid with bitter taste, was used as a model drug to mask its taste with dowex2 (weak base anion exchange resin). The taste masking of a drug using ion exchange resin basically depends on the complex formation between the drug and a specific type of resin. Complex formation under various preparation conditions including; the ratio of drug to resin, mixing time, the pH of the processing medium and the concentration of valsartan was investigated in this study. Optimum conditions for complex formation and maximum drug load were obtained at a drug-resin ratio 1:8, mixing time 4 hours, pH 6.8, temperature 50º C and drug concentration 0.02% w/v. The drug resin ate complex was evaluated for the drug content, taste, drug release and molecular properties. The resinate formation was confirmed using different analytical techniques like thermal analysis using differential scanning calorimetry (DSC), spectroscopic method like Fourier transform infrared spectroscopy (FTIR) and by X-ray powder diffraction analysis (XRPD).

Preparation and characterization of taste masked valsartan by ion-exchange resin approach

The bitter taste is one of the most important drug formulation problems. The unpleasant taste leads to noncompliance, which consequently decreases the therapeutic efficacy of the drug. Therefore, masking of bitter taste is very important in drug formulation. In this study an antihypertensive drug, valsartan, which is a weak acid with bitter taste, was used as a model drug to mask its taste with dowex2 (weak base anion exchange resin). The taste masking of a drug using ion exchange resin basically depends on the complex formation between the drug and a specific type of resin. Complex formation under various preparation conditions including; the ratio of drug to resin, mixing time, the pH of the processing medium and the concentration of valsartan was investigated in this study. Optimum conditions for complex formation and maximum drug load were obtained at a drug-resin ratio 1:8, mixing time 4 hours, pH 6.8, temperature 50º C and drug concentration 0.02% w/v. The drug resinate complex was evaluated for the drug content, taste, drug release and molecular properties. The resinate formation was confirmed using different analytical techniques like thermal analysis using differential scanning calorimetry (DSC), spectroscopic method like Fourier transform infrared spectroscopy (FTIR) and by X-ray powder diffraction analysis (XRPD).

A conceptual hybrid process flowsheet for platinum group metals (PGMs) recovery from a chromite-rich Cu-Ni PGM bearing ore in oxidized mineralization through a single-stage leach and adsorption onto ion exchange resin

The availability of oxidized PGM ore deposits, at or near the earth's surface, present lucrative prospects for future PGM production owing to the large resource estimates, the relatively high PGM grades and they can be mined through relatively lower-cost open-pit mining processes. However, these oxidized PGM ores are currently not mined or treated due to insufficient recoveries using established metallurgical techniques. The complex mineralogy and polymodal distribution of PGM in the oxidized ores pose a number of challenges to the metallurgist from a mineral liberation and extraction perspective.A conceptual route to the integrated processing of a Ni-Cu-PGM bearing chromite ore in oxidized mineralization for the recovery of base and precious metals is presented based upon earlier work of the authors and recent research on metal recovery from solution. This paper presents laboratory batch-scale results of simultaneous adsorption of Pd(II) and Pt(IV) onto commercially available weak-base anion exchange resin, diethylaminoethyl (DEAE) cellulose, from hydrochloric acid solutions. Effects of various variables such as equilibration time, thiocyanate and tin chloride concentrations were studied.Without any prior scrubbing step to remove co-extracted impurities, the uptake of Pd(II) and Pt(IV) was successfully accomplished with recoveries approximating 100% within 15 min. The presence of Fe(III) and other non-ferrous metal accompanying ions didn't show any marked tendency to adsorb. Among the adsorption parameters, thiocyanate concentration had the most significant effect on the process. The dual role of Sn(II) i.e. labilizing agent and PGM collector at a time, was simply overridden, overshadowed by the DEAE high selectivity for PGMs. Thiourea proved to be a better stripping reagent for bulk elution of combined Pd(II) and Pt(IV). A conceptual flowsheet is disclosed for hydrometallurgical pilot scale testing, economic evaluation and assessment of potential environmental impacts.

Polyamine functionalised ion exchange resins: Synthesis, characterisation and uranyl uptake

A series of linear polyamine functionalised weak base anion exchange resins have been synthesised using the Merrifield resin and characterised using infra-red spectroscopy, thermogravimetry, elemental analysis and solid state 13C nuclear magnetic resonance spectroscopy. Uptake behaviour towards uranium (as uranyl) from sulfuric acid media has been assessed as a function of pH and sulfate concentration, with comparison to a commercially available weak base anion exchange resin, Purolite S985. Synthetic polyamine resins were seen to outperform the commercial resin at industrially relevant uranyl concentrations, with a trend of increased uptake being seen with increasing polyamine chain length. Uranium loading isotherm studies have been performed and fit with the Langmuir and Dubinin-Radushkevich isotherm models, with a maximum loading capacity observed being 269.50 mg g−1 for the longest polyamine chain studied. Extended X-ray absorption fine structure experiments have been used to determine uranium coordination environment on the resin surface, showing a [UO2(SO4)3]4− species. This coordination knowledge was employed to develop an extraction mechanism and derive an isotherm model based on the law of mass action.

SORPTION OF RHENIUM FROM SULFURIC ACID SOLUTIONS BY IMPREGNATES CONTAINING TRIALKYLAMINES

The paper studies rhenium (VII) sorption from sulfuric acid solutions by impregnates based on macroporous polymer carriers (copolymers of styrene with divinylbenzene, weak acid cation exchange resion) containing commercial trialkylamine (ТAA). The study provides equilibrium and kinetic characteristics of rhenium recovery by the impregnate based on the macroporous weakly acidic cation exchange resin (K-TAA) having the best rhenium capacity. The maximum coefficient of rhenium distribution in the K-TAA impregnate is observed in sorption from pH = 2 solutions. The rhenium sorption isotherm is described by the Langmuir equation with the K = 29±2 ml/g constant. A limited solution volume method was used to obtain the integral kinetic curves of sorption with a half-reaction time value considered to calculate the effective coefficients of rhenium diffusion in the impregnate amounted to (3,8·10–11 (295 K) and 1,3·10–10 (308 K) m2/s). Kinetic results linearized by the equations of models (pseudo-first, pseudo-second order, Elovich and inner diffusion) showed that kinetic curves with the highest correlation degree are described by the pseudo-second order equation with the 0,00056 (295 K) and 0,00059 (308 K) g·mg–1·min–1 rate constants. The apparent activation energy of rhenium sorption (39±2 kJ/mol) was calculated using the Arrhenius equation. The K-TAA impregnate was tested for rhenium sorption from the eluate obtained by rhenium desorption from the Purolite A170, weak base anion exchange resin pre-saturated with rhenium from the complex pregnant solution for leaching of products derived from poor rhenium-containing copper sulfide raw materials processed.

Efficient in situ separation and production of L-lactic acid by Bacillus coagulans using weak basic anion-exchange resin.

To get rid of the dependence on lactic acid neutralizer, a simple and economical approach for efficient in situ separation and production of L-lactic acid was established by Bacillus coagulans using weak basic anion-exchange resin. During ten tested resins, the 335 weak basic anion-exchange resins demonstrated the highest adsorption capacity and selectivity for lactic acid recovery. The adsorption study of the 335 resins for lactic acid confirmed that it is an efficient adsorbent under fermentation condition. Langmuir models gave a good fit to the equilibrium data at 50°C and the maximum adsorption capacity for lactic acid by 335 resins was about 402mg/g. Adsorption kinetic experiments showed that pseudo-second-order kinetics model gave a good fit to the adsorption rate. When it was used for in situ fermentation, the yield of L-lactic acid by B. coagulans CC17 was close to traditional fermentation and still maintained at about 82% even after reuse by ten times. These results indicated that in situ separation and production of L-lactic acid using the 335 resins were efficient and feasible. This process could greatly reduce the dosage of neutralizing agent and potentially be used in industry.

The effectiveness of ion exchange resins in separating uranium and thorium from rare earth elements in acidic aqueous sulfate media. Part 1. Anionic and cationic resins

Conventional ion exchange resins with different functional groups were evaluated for their potential application in separating uranium U(VI) and thorium Th(IV) from rare earth elements RE(III). The resins studied comprised strong- and weak-base anion exchange resins, and strong- and weak-acid cation exchange resins. The selectivity of these resins to adsorb U(VI) and Th(IV) in the presence of selected RE(III) was examined in sulfuric acid media of varying concentrations. It was evident that the adsorption performance of the resins was acid concentration-dependent. Most candidate resins had potentially feasible selective adsorption at or below 0.1mol/L H2SO4 (pH≥0.7). Within the group of anion exchange resins, both the strong- and weak-base resins exhibited a similar selectivity with U(VI) adsorbed in preference to RE(III). The difference between them was their adsorption of Th(IV). The weak-base resin with primary amine functional group demonstrated superior separation of Th(IV) from RE(III). For this resin, 78% of U(VI) and 68% of Th(IV) were adsorbed while RE(III) co-adsorption was <5% at 0.0005mol/L H2SO4 (pH3). In the case of the strong-acid cation exchange resins, Th(IV) and RE(III) were adsorbed in preference to U(VI), i.e., RE(III)>Th(IV)>>U(VI). The weak-acid cation exchange resins, on the other hand, displayed limited adsorption of all elements.

An increase in purity of ammonium perrhenate solutions with respect to molybdenum(IV) with the sorption recovery of rhenium(VII) from Mo-containing solutions

The possibility of the additional purification of ammonia rhenium desorbates with respect to molybdenum in the course of the sorption recovery of rhenium from Mo-containing solutions with the help of Purolite A170 and Purolite A172 weak base anion-exchange resins is considered. The pH-dependence of sorption of Re(VII) and Mo(VI) on these anion-exchange resins is investigated in static conditions with the 1 M (NH4)2SO4 background in the solution. It is shown that the range of pH, in which anion-exchange resins retain the ability to sorb Re(VII), is also spread to a weakly basic region. A substantial decrease in the adsorption of Re(VII) starts already with an increase in pH above 7.5. The capacity of anion-exchange resins with respect to Mo(VI) starts to decrease noticeably with an increase in pH of solutions above 5.0, and molybdenum almost ceases to sorb by both anion-exchange resins upon reaching pH ~ 7.0. In order to decrease the Mo(VI) content in rhenium desorbates with the sorption recovery of Re(VII) from Mo-containing solutions on weak base anion-exchange resins, the following flowsheet is suggested. Initially, the main amount of sorbed Mo(VI) is desorbed by contacting the saturated anion-exchange resin with the ammonium sulfate solution upon mixture stirring and holding constant pH of the solution in limits of 7.0–7.5 due to the addition of dosed amounts of ammonia solution. Then anion-exchange resin is separated from the ammonium sulfate solution containing Mo(VI), washed with water, and Re(VII) is desorbed by ammonium solution in dynamic conditions. The verification of the proposed method for the resins saturated by sorption from the model solution of the composition, g/L, 98 H2SO4, 4 Mo(VI), and 0.5 Re(VII) showed the occurrence of desorption of no less than 90% sorbed molybdenum during the treatment of anion-exchange resins with ammonium sulfate solution. Herewith, concentration ratio Re(VII) : Mo(VI) in ammoniacal rhenium desorbates when using A170 anion-exchange resin increases 11-fold and when using A172 anion-exchange resin, it increases 20-fold compared with that attained without the additional washing of Mo(VI). Losses of Re(VII) with the Mo-containing desorbate (reversible) do not exceed 5.2% of the amount of sorbed Re(VII).

Phosphate recovery from treated municipal wastewater using hybrid anion exchangers containing hydrated ferric oxide nanoparticles

AbstractBACKDROUNDThis study presents the evaluation of two ion exchangers (granular and fibrous) impregnated with nanoparticles of hydrated ferric oxide (HFO) as selective sorbents for phosphate recovery from aqueous solutions. The hybrid impregnated anion exchangers combine the durability and mechanical strength of a polymeric weak base anion exchange resin with the high sorption affinity of HFO towards phosphate species. Dynamic experiments were carried out and data obtained were fitted to a well‐known fixed‐bed sorption model.RESULTSThe theoretical sorption capacities reported by the Thomas model were in good agreement with the breakthrough experimental capacities determined from the sorption data. The sorption capacity decreased when using wastewater treatment plant secondary effluents in comparison with synthetic water mainly owing to the presence of organic matter and suspended solids. The phosphate sorbed on the impregnated ion exchangers was efficiently desorbed by using a 0.5 mol L‐1 sodium hydroxide solution, reporting up to 90% of recovery.CONCLUSIONThe reusability of sorbents was evaluated through five sorption–desorption working cycles. Fiban‐As was able to operate up to three consecutive cycles with good sorption performance while a significant decrease of sorption capacity after the first cycle was observed for FO36 resin. © 2017 Society of Chemical Industry

Adsorption of Benzenesulfonic Acid on a Novel Dual Functional Weakly Basic Anion Exchanger from Aqueous Solution

A novel weakly basic anion exchange resin AEC-5 bearing two differently sized functional groups was prepared through chloromethylated PS-DVB copolymer beads reaction with a mixture of dibutylamine and dimethylamine. To better understand the benefits of AEC-5 for removing benzenesulfonic acid (BSA) from aqueous solution, adsorption properties of BSA on AEC-5 were compared with two monofunctional anion exchange resins, a commercial exchanger D301 derived from dimethylamine and a synthesized resin AEC-4 derived from dibutylamine. Adsorption isotherms and effect of solution pH, temperature, time, and coexisting Na2SO4 on sorption behavior were investigated and column adsorption-regeneration tests were carried out. AEC-5 showed a greater adsorption capacity than both monofunctional anion exchangers for BSA in the presence of Na2SO4. Equilibrium and kinetic data could be well matched with the Langmiur isotherm model and pseudo-second-order model respectively. AEC-5 had better adsorption kinetics than AEC-4. Thermodynamic parameters were also analyzed and results indicate that BSA adsorption on AEC-5 is an exothermic and spontaneous process. AEC-5 is very likely to be a potential alternative adsorbent, which is believed to possess an excellent selectivity for BSA over sulfate, acceptable kinetics, and desorption characteristics, for its application in industrial wastewater treatment.

An efficient process for obtaining prebiotic oligosaccharides derived from lactulose using isomerized and purified whey permeate.

One of the most promising uses of whey permeate (WP) is the synthesis of prebiotic oligosaccharides. Herein, commercial WP was submitted to chemical isomerization catalysed by sodium borate at an alkaline pH and subsequent purification using anion-exchange resins to remove boron. Subsequently, purified mixtures were used to synthesize prebiotic oligosaccharides using β-galactosidase from Bacillus circulans. Isomerization of concentrated WP (200 g L-1 lactose) gave rise to levels of lactulose up to 155.5 g L-1 after 30 min of reaction (molar ratio of boron/lactose, 1/1; pH 12; 70 °C). Boron was removed from the isomerized WP (IWP) using the combination of a strong acid (IR-120, H+ ) and a weak base (IRA-743) anion-exchange resins, reducing its level to <1 ppm, without loss of lactulose. During the transglycosylation reaction of purified IWP (lactose/lactulose ratio, 1/2.4) maximum content of prebiotic compounds was achieved, i.e. 690 g kg-1 WP after 3 h of reaction. This study shows that combined chemical-enzymatic reactions together with the purification of IWP results in an efficient synthesis of prebiotic oligosaccharides. © 2017 Society of Chemical Industry.

Sorption of humic substances on a weakly basic anion-exchange resin: Relationship with the adsorbate structure

Adsorption of a broad range of humic substances (HS) of different origins and fractional compositions on a macroporous weakly basic anion-exchange resin is studied. It is found that the nature of the HS has a substantial effect on both the efficiency of sorption and the mechanism of interaction with the adsorbent. The dependence of the determined thermodynamic parameters of sorption on the HS origin, composition, and structure is shown for a broad range of HS. It is concluded that the results can be used to predict the sorption properties of weakly basic anion-exchange resins with respect to HS of known origin and structural group composition.

Adsorption Behaviour of Lactic Acid on Granular Activated Carbon and Anionic Resins: Thermodynamics, Isotherms and Kinetic Studies

Solid-liquid extraction (adsorption or ion exchange) is a promising approach for the in situ separation of organic acids from fermentation broths. In this study, a diluted concentration of lactic acid (&lt;10 g/L) separation from a model fermentation broth by granular activated carbon (GAC) as well as weak (Reillex® 425 or RLX425) and strong (Amberlite® IRA-400 or AMB400) base anion exchange resins under various operating conditions was experimentally investigated. Thermodynamic analysis showed that the best lactic acid adsorption performances were obtained at a pH below the pKa value of lactic acid (i.e., 3.86) for GAC and RLX425 by physical adsorption mechanism and above the pKa value for the AMB400 resin by an ion exchange mechanism, respectively. The adsorption capacity for GAC (38.2 mg/g) was the highest, followed by AMB400 (31.2 mg/g) and RLX425 (17.2 mg/g). As per the thermodynamic analysis, the lactic acid adsorbed onto GAC and RLX425 through a physical adsorption mechanism, whereas the lactic acid adsorbed onto AMB400 with an ion exchange mechanism. The Langmuir adsorption isotherm model (R2 &gt; 0.96) and the pseudo-second order kinetic model (R2 ~ 1) fitted better to the experimental data than the other models tested. Postulating the conditions for the real fermentation broth (pH: 5.0–6.5 and temperature: 30–80 °C), the resin AMB400 represents an ideal candidate for the extraction of lactic acid during fermentation.

Impact of chloride on uranium(VI) speciation in acidic sulfate ion exchange systems: Towards seawater-tolerant mineral processing circuits

Using X-ray absorption spectroscopy, we have identified the mechanism by which chloride impacts the extraction of U(VI) by a weak base anion exchange resin from acidic sulfate solutions. The amount of chloride present affects U(VI) speciation both in the feed solutions and adsorbed by the resin, and we find three distinct U(VI) species taken up by the resin across the salinity gradient, directly corresponding to changes in levels of U(VI) extraction. These findings are integral to the effective design of mineral processing circuits incorporating seawater—a cheaper and more sustainable water source than fresh water.

PURITY UPGRADE OF AMMONIUM PERRHENATE SOLUTIONS IN RESPECT OF MOLYBDENUM (VI) AT SORPTION RECOVERY OF RHENIUM (VII) FROM SOLUTIONS CONTAINING MOLYBDENUM (VI)

The study covers the method of additional cleaning of ammonium perrhenate desorbates from molybdenum through sorption recovery of rhenium from Mo-containing solutions with Purolite A170 and A172 weak base anion exchange resins. The dependence of Re(VII) and Mo(VI) sorption using these resins on solution pH was studied under static conditions with the 1 M (NH 4 ) 2 SO 4 solution. It was found that the pH range at which the resins retain the ability of Re(VII) sorption extends to a weak-alkaline area. A significant decrease in Re(VII) adsorption begins when pH exceeds 7,5 Mo(VI) capacity of the resins decreases significantly when solution pH exceeds 5,0, and both anion exchange resins practically stop molybdenum sorption at above pH ~ 7,0. Reduction of Mo(VI) content in rhenium desorbates obtained in sorption recovery of Re(VII) from Mo-containing solutions with weak base anion exchange resins can be achieved as follows. First, major quantity of adsorbed Mo(VI) is desorbed from the loaded resin by ammonium sulfate solution when stirring the mixture and keeping pH constant in the 7,0–7,5 range by dosing the ammonia solution. Then the resin is separated from the Mo(VI)-containing ammonia solution, washed with water, and Re(VII) is desorbed by the ammonia solution in dynamic conditions. The proposed method was verified with anion exchangers loaded in sorption from the model solution with the following composition, g/L: 98 H 2 SO 4 , 4 Mo(VI), 0,5 Re(VII). It was shown that resin treatment with the ammonium sulfate solution removes at least 90 % of adsorbed molybdenum. A ratio of Re(VII) to Mo(VI) concentrations in ammonium perrhenate desorbates increases by 11 times with Purolite A170 resin, and by 20 times with Purolite A172 resin compared to the results obtained without an additional Mo(VI) washing. Re(VII) losses (reversible) with the Mo-containing desorbate are below 5,2 % of the adsorbed Re(VII) amount.

Sorption recovery of rhodium(III) from multicomponent chloride solutions in the presence of tin(II) chloride

The influence of tin (II) chloride additives on sorption of Rh(III) on the Purolite S920 ion exchange resin with isothiouronium groups, the Purolite S985 weak base anion exchange resin, and the Purolite A500 strong base anion exchange resin is investigated. It is established that the introduction of SnCl2 leads to a substantial increase in selectivity of all tested ion exchange resins to Rh(III) and in the sorption rate of Rh(III) on S985 and S920 ion exchange resins. The optimal dosage of SnCl2 (0.01 mol/L) at which the distribution coefficients of Rh(III) during sorption for all tested ion exchange resins reach maximal values is determined. It is shown that almost quantitative recovery of Rh(III) is attained when passing the multicomponent chloride solution of the composition (g/L) 0.2 Rh(III), 72.9 HCl, 53.5 NH4Cl, 2.7 Al(III), 1.23 Fe(III) and 5.9 Sn(IV) with the SnCl2 additive through the Purolite S920 ion exchange resin with isothiouronium groups. Desorption of Rh(III) from the Purolite S920 saturated ionite with the acidified thiourea solution is incomplete, no greater than 60%.

Synthesis, characterization and application of ion exchange resin as a slow-release fertilizer for wheat cultivation in space

In addition to the bio-regenerative air revitalization, water recycling and waste management systems and their associated challenges, enhancing the crop yield with less fertilizer input for sustainable food production in space is also a challenge that needs to be overcome. The purpose of this study is to investigate the feasibility of applying ion exchange resin as a slow-release fertilizer for wheat cultivation in space. Strong-acid cationic exchange resins and weak-base anion exchange resins soaked in 1X, 5X, 10X and 15X Hoagland nutrient solutions, respectively, were used as fertilizers in clinoptilolite to cultivate wheat plants, and the morphological and physiological characteristics of the wheat plants were studied and compared with that of the wheat planted in vermiculite and nutrient solutions. The results showed that more ions were attached on the surface of the ion exchange resins as the solution concentration increased. After 14 days, the fresh weight of wheat planted in the ion exchange resin-clinoptilolite (IER-clinoptilolite) treated with 10X and 15X solutions were 190% and 192% higher than that of wheat planted in nutrient solution with the same concentration. Chlorophyll content of wheat plants cultivated in the two kinds of solid medium is significantly higher than that of liquid cultivation. The lowest peroxidase (POD) activity and malondialdehyde (MDA) contents of wheat plants cultivated in the IER-clinoptilolite appeared on the 14th day. According to all the experimental data, it's promising to produce slow-release nutrient fertilizer by using strong-acid cationic exchange resins and weak-base anion exchange resins for wheat cultivation in space.

Equilibrium Studies on Phenol Removal from Industrial Wastewater Through Polymeric Resins

The efficient removal of phenol from industrial wastewaters has increasingly become a significant environmental concern due to its high toxicity even at low concentrations. In this research work, phenol removal from aqueous solution was evaluated by using Amberlyst A26, a strong-base anion exchange resin, and Amberlite IRA-67, a weak-base anion exchange resin. The influence of phenol concentration in the feedstream was investigated as well as the effect of recirculation time. In addition, equilibrium data fitted to theLangmuir, Freundlich and Temkin isotherms showed that the best correlation is given by Langmuir isotherm for both resins (R2 = 0.99). Experimental results revealed that phenol uptake is a spontaneous process for Amberlyst A26 (?G° = -1.55 kJ mol-1), whereas it is not spontaneous for Amberlite IRA-67 (?G° = 3.06 kJ mol- 1). Finally, Amberlyst A26 was confirmed to be considerably more efficient than Amberlite IRA-67 for thepotential removal of phenol from industrial effluents.