Batch Extraction Experiments Research Articles

Optimization of Ultrasonic Extraction of Total Flavonoids from Cinnamonum zeylaniccum

Cancer is the most widespread disease in the world currently. The availability of using controlled-drug-releasing capsules for those cancer diseases had become more and more important. The initial operation of the production process of the capsules requires the extraction of the active ingredients from the plant. Phytochemicals exert positive effects on human health and thus they are important compounds found in medicinal plants like Cinnamonum zeylaniccum . Flavonoids are the most effective phytochemicals having more than four thousand different types and they are well known antioxidants especially used in treatments of cancer diseases. In the light of these information, the aim of this study was to optimize the ultrasonic extraction of flavonoids (as a raw-material fort he capsules) from Cinnamonum zeylaniccum with methanol by using Response Surface Methodology. Batch extraction experiments had been carried out with the parameters of solid-to-liquid ratio, extraction temperature and time, by applying ultrasounds on sweep mode. Multi-parameter optimization was carried out with three-parameter, three-level, three-centered Box-Behnken design considering the optimum values obtained in single-parameter optimization. Design-Expert software was used to obtain the function representing the extraction yield surface depending on the selected parameters. As a result of the statistical analysis, the function expressing the effect of the parameters on the resulting amount of quercetin production in industry had been derived as reduced cubic model. Solid-to-liquid ratio was found as the most effective parameter on the extraction yield. At the optimum conditions (30°C, 1/10 g/ml, and 15 minutes), 12.34 mg quercetin equivalent total flavonoids were extracted.

Modeling of simultaneous extraction of uranyl nitrate and nitric acid by 36 vol.% tri-iso-amyl phosphate in n-dodecane

The simultaneous extraction of uranyl nitrate and nitric acid by 36 vol.% tri-iso-amyl phosphate (TiAP) in n-dodecane was experimentally studied and modeled. The batch extraction experiments were carried out at low concentration region of aqueous uranyl nitrate by 36 vol.% TiAP in n-dodecane at 25 °C. The non idealities in aqueous phase were described by eNRTL model. The predicted organic phase concentration of nitric acid and uranyl nitrate obtained by considering the HNO3·TiAP and UO2(NO3)2·2TiAP species in the organic phase is in good agreement with the experimental data.

Fate of metals before and after chemical extraction of incinerated sewage sludge ash

Chemical extraction of incinerated sewage sludge ash (ISSA) can effectively recycle P, but it may change the speciation and mobility of the remaining metals. This study investigated the changes of the leaching potential and distribution of metals in the chemically extracted ISSA. Batch extraction experiments with different extractants, including inorganic acids, organic acids, and chelating agents, were conducted on the ISSA collected from a local sewage sludge incinerator. The extraction of Zn, Cu, Pb, Ni, Cd, Ba, Cr and As from the ISSA and the corresponding changes of the mobility and speciation were examined. The results showed that the metals in ISSA were naturally stable because large portions of metals were associated with the residual fraction. The inorganic (HNO3 and H2SO4) and organic acids (citric acid and oxalic acid) significantly co-dissolved the metals through acid dissolution, but the reduction in the total concentrations did not tally the leaching potential of the residual metals. The increase in the exchangeable fraction due to destabilization by the extractants significantly enhanced the mobility and leachability of the metals in the residual ISSA. Chelating agents (EDTA and EDTMP) only extracted a small quantity of metals and had a marginal effect on the fate of the residual metals, but they significantly reduced the Fe/Mn oxide-bound fraction. In comparison, the bioaccessibility of residual metals were reduced to varying extent. Therefore, the disposal or reuse of chemically extracted ISSA should be carefully evaluated in view of possible increase in mobility of residual metals in the environment.

Remediation of metal-contaminated paddy soils by chemical washing with FeCl3 and citric acid

Batch extraction experiments were conducted to investigate the chemical washing of metal-contaminated paddy soils using mixtures of ferric chloride (FeCl3) and citric acid (CTA). The effects of the extractants (FeCl3, CTA, or FeCl3 + CTA) and washing cycles (single-step or multistep washing) on the metal removal efficiency were studied. FeCl3 + CTA increased metal removal efficiency to some extent compared to single FeCl3 or CTA. When the liquid-to-solid ratio was 2:1 with three washes and two rinses, a mixture of 10 mmol L−1 FeCl3 and 20 mmol L−1 CTA removed 78.9% Cd, 15.8% Cu, 34.0% Zn, and 18.1% Pb from a Typic Fe–accumuli–Stagnic Anthrosols. Using multistep washing instead of single-step increased the metal extraction effect. Moreover, the removal efficiency and speciation of metals in different soils and changes in soil properties in washed soils were also studied. The removal rate of Cd was higher than that of Zn, Cu, or Pb because of the higher proportions of acid-soluble forms of Cd in the soils. The removal of metals from different soils depended on the distribution of metal speciation and soil type. Soil pH, CEC, exchangeable Ca, and exchangeable Mg decreased significantly after soil washing. We conclude that chemical washing of metal-contaminated paddy soils with mixtures of FeCl3 and citric acid may be a feasible technique for soil remediation.

Liquid-liquid extraction equilibrium for pyruvic acid recovery: experimental data and modeling

ABSTRACT Physical extraction studies of pyruvic acid from dilute aqueous solutions (0.025 kmol·m-3 to 0.200 kmol·m-3) using several pure solvents (tri-n-butylphosphate (TBP), 1-decanol, 1-octanol, toluene, Methyl-isobutylketone (MIBK), and n-heptane) and their binary mixtures are reported in this work. All the batch extraction experiments were carried out at isothermal conditions (T=303±1K) and the results are reported in terms of distribution coefficient (K D). The results obtained by the equilibrium studies of the different extraction system were correlated with solvatochromic parameters of the solvents. A linear solvation energy relationship (LSER) model was applied to interpret the extraction equilibrium which specifically considers physical interactions. The values of the LSER model parameters for the extraction system were optimized by regression technique and the model equations have been proposed. Experimental and model values were in good agreement (RMSD < 0.1).Reported outcomes are useful in the selection of a suitable extraction system and understanding the extraction mechanism for the separation of pyruvic acid from dilute aqueous solutions.

Identification of root exudates from the Pb-accumulator Sedum alfredii under Pb stresses and assessment of their roles

ABSTRACTThe Pb-accumulator Sedum alfredii is a good phytoremediation material, and widely used in the phytoremediation research of soils contaminated with Pb. The root exudates from it may be playing a significant role in the process of phytoremediation. In this study, the metabonomics method which based on gas chromatography–mass spectrometry (GC–MS) and pattern recognition analysis was used to identify the remarkable root exudates from S. alfredii under different Pb stresses, including exposure concentrations (0, 10, 50, 200 and 1000 µmol/L) and times (4 and 8 days). And batch extraction experiments were used to verify the roles of these remarkable root exudates. According to the results, 11 metabolites were considered as the remarkable metabolites. Oxalic acid, galactonic acid and glyceric acid can remove Pb in soil, and the removal effect was: oxalic acid > galactonic acid > glyceric acid. Xylose, glucose and maltose have no removal effect for Pb in soil.

Tailor-made approach for selective isolation and elution of low-density lipoproteins by immunoaffinity sorbent on silica

Immunoaffinity procedure was developed for isolation of low density lipoprotein (LDL) from biological samples by using silica-derived immunoaffinity sorbent. Sorbent was prepared by immobilization of monoclonal anti-apoB-100 antibody onto macroporous silica particles, using carefully optimized binding chemistry. Binding capacity of the sorbent towards LDL was determined by batch extraction experiments with solutions of isolated LDL in phosphate-buffered saline, and found to be 8 mg LDL/g. The bound LDL fraction was readily released from the sorbent by elution with ammonia at pH 11.2. The total time needed for isolation procedure was less than 1 h, with LDL recoveries being essentially quantitative for samples containing less than 0.3 mg LDL/mL. With higher concentrations, recoveries were less favorable, most probably due to irreversible adsorption caused by LDL aggreggation. However, reusability studies with isolated LDL at concentration 0.2 mg/mL indicate that the developed immunoaffinity material may be used for multiple binding-release cycles, with minor losses in binding capacity. Finally, the sorbent was successfully applied to isolation of LDL from diluted plasma. Apart from its practical implications for LDL isolation, this study provides crucial insights into issues associated with LDL-sorbent interactions, and may be useful in future efforts directed to development of lipoprotein isolation approaches.

Behavior of Molybdenum (VI) in {DMDOHEMA–HDEHP/nitric acid} Liquid–Liquid Extraction Systems

ABSTRACTThe EXAm (extraction of americium) process was developed for americium recycling in future nuclear fuel cycles. In this solvent extraction system, a combination of two extractants, N,N′-dimethyl-N,N′-dioctyl-hexylethoxy malonamide (DMDOHEMA) and di-2-ethylhexyl phosphoric acid (HDEHP), in TPH (hydrogenated tetrapropylene) is used to extract americium in the first step of the process at high acidity (HNO3 5–6 M). Americium is co-extracted with light lanthanides and other fission products like molybdenum, iron, ruthenium, etc.. Molybdenum is selectively scrubbed during the second step at low acidity using citric or glycolic acid as a buffer and complexing agent. The speciation of Mo(VI) in aqueous solutions is highly dependent on acidity and Mo concentration. In this article, a simple thermodynamical model is proposed for Mo(VI) scrubbing based on batch extraction experiments (with pH and cation concentration variations) and stoichiometries of complexes formed in the organic phase according to electrospray ionization mass spectrometry (ESI-MS) experiments and published data on Mo(VI) speciation. At high acidity ([HNO3] > 1 M), the MoO22+ species is strongly extracted by the solvent DMDOHEMA–HDEHP according to a solvate mechanism. At lower acidity ([HNO3] < 1 M), cation exchange mechanisms become predominant and DMDOHEMA does not participate to the extraction Mo(VI) anymore. During Mo scrubbing at pH higher than 1, the extraction of Mo as neutral species (like MoO3) and anionic species (like MoO42–) has to be taken into account in the model to predict the “bell-shape” of Mo distribution ratio evolution as a function of pH. This model was then implemented in the PAREX simulation code developed by the CEA to build the flowsheet for the “Mo scrubbing” section of EXAm process and predict Mo concentrations profiles in batteries of mixer-settlers during pilot-scale tests.

Targeting fluorescent lamp waste for the recovery of cerium, lanthanum, europium, gadolinium, terbium and yttrium

Owing to the ever-growing demand and supply problems, rare earth elements (REEs) are now considered to be some of the most critical elements. This has focused attention towards their recovery from end-of-life products and industrial waste streams. A hydrometallurgical approach was carried out to assess the recycling potential of REEs from fluorescent lamp waste. In comparison to other efforts in this field, these investigations were carried out using real waste samples originating from a discarded lamp processing facility. Leaching of metals from the waste was studied using nitric, hydrochloric, sulphuric and methane sulphonic acid solutions. Separation of REEs from nitric acid media was investigated using solvent extraction. Batch extraction experiments were carried out using Cyanex 923, a commercial mix of trialkylphosphine oxides. Separation of heavier REEs (terbium, europium and gadolinium) and yttrium from lighter REEs (cerium and lanthanum) is possible due to larger separation factors. Selective stripping of REEs from the co-extractable species (iron and mercury ions) was easily achieved using 4 M hydrochloric acid. Further recovery of the extracted iron and mercury, with either oxalic acid or nitric acid solutions, allows for the subsequent re-use of the organic phase in the process.

Effect of Solvent and pH on the Extraction of Carbolic Acid from Aqueous Solution by TOMAC

Studies on the extraction of carbolic acid (phenol) at different pHs by trioctyl methylammonium chloride (TOMAC) diluted in octane, decan, octan-1-ol, and decan-1-ol are reported. Experimental results of batch extraction experiments are calculated and reported for distribution coefficients (KD), loading factors (Z), and extraction efficiency (E). All measurements were carried out at 298.15 K. The maximum removal of phenol was observed to be 88.679% at pH = 5 for octan-1-ol. The results of the liquid–liquid equilibrium measurements were correlated with a linear solvation energy relationship (LSER) model, which takes into account physical interactions. The remaining parameters were fitted to the experimental results. Experimental results for the liquid–liquid equilibrium were compared to the model. The LSER model was applied to correlate experimental values.

Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions

Oxalic acid enhances arsenic (As) mobilization by dissolving As host minerals and competing for sorption sites. Oxalic acid amendments thus could potentially improve the efficiency of widely used pump-and-treat (P&T) remediation. This study investigates the effectiveness of oxalic acid on As mobilization from contaminated sediments with different As input sources and redox conditions, and examines whether residual sediment As after oxalic acid treatment can still be reductively mobilized. Batch extraction, column, and microcosm experiments were performed in the laboratory using sediments from the Dover Municipal Landfill and the Vineland Chemical Company Superfund sites. Oxalic acid mobilized As from both Dover and Vineland sediments, although the efficiency rates were different. The residual As in both Dover and Vineland sediments after oxalic acid treatment was less vulnerable to microbial reduction than before the treatment. Oxalic acid could thus improve the efficiency of P&T. X-ray absorption spectroscopy analysis indicated that the Vineland sediment samples still contained reactive Fe(III) minerals after oxalic acid treatment, and thus released more As into solution under reducing conditions than the treated Dover samples. Therefore, the efficacy of enhanced P&T must consider sediment Fe mineralogy when evaluating its overall potential for remediating groundwater As.

TEHDGA, DMDOHEMA and Mixed Sorbents: Characterization and Am(III) Uptake Properties

The Atalante research facility produces radioactive waste that have to be managed according to specific rules. In particular, solid and liquid wastes need to be transferred to another facility in Marcoule to be evaporated with an alpha activity limit of 16.65 GBq/m3. The radioactive aqueous nitric acid wastes produced in Atalante must be first decontaminated by removing U, Pu and minor actinides and therefore a dedicated decontamination program for radioactive aqueous nitric acid wastes is implemented in Atalante. In particular, the recovery of americium and curium is obtained by extraction chromatography. TEHDGA (N, N, N’, N’-tetra-2-ethylhexyl-3-oxopentane-1,5-diamide), DMDOHEMA ((N,N’-dimethyl-N,N’-dioctylhexyloxyethyl malonamide) and a mixture of both extractants were impregnated on silica gel and studied.Batch experiments were made to determine the performances of such a process. The weight distribution coefficients (Dw) were determined for Am and Nd. Different kinetic behavior was found with both complexants. An effect of nitric acid concentration was observed. For three solids, the americium's uptake increases with acidity. Loading capacities by isotherm and Langmuir isotherm are obtained (between 48mg.g-1 and 94mg.g-1). After determining various parameters in batch extraction experiments, the performances of the solid supports were studied in columns. The breakthrough and elution curves were obtained with neodymium (respectively between 12mg.g-1 and 21mg.g-1; 0.17 and 0.27 L.g-1). Capacity and recovery were optimized with the mixture of DMDOHEMA and TEHDGA.

Removal of pesticides from wastewater by ion pair Centrifugal Partition Extraction using betaine-derived ionic liquids as extractants

The extraction of pesticides from aqueous solutions using new ionic liquids (ILs) derived from glycine betaine as extractants was investigated. These ILs incorporate cationic esters of trimethyl(2-alkoxy-2-oxoethyl) ammonium (GBOCn+) associated with inorganic ClO4− or BF4− anions. First, batch extraction experiments were performed by using the liquid–liquid biphasic system IL/ethyl acetate/water (1:1:1; v/v) for four commonly used pesticides: 4-chlorophenoxyacetic acid (4-CPA), 2,4-dichlorophenoxyacetic acid (2,4-D), 2-[(4-methyl-5-oxo-3-propoxy-1,2,4-triazolin-1-yl)carbamidosulfonyl]benzoic acid methyl ester sodium salt (propoxycarbazone) and 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-5-methoxymethyl nicotinic acid (imazamox). Then, the liquid–liquid extraction unit operation was intensified by transposing the system into a Centrifugal Partition Extraction (CPE) device, using ethyl acetate/n-butanol/water (1:4:5; v/v) as biphasic solvent system and potassium iodide, sodium iodide or sodium perchlorate as potential displacers. The use of a lab-scale CPE column with a capacity of 300mL allowed the intensification of the extraction procedure. The extraction and back-extraction of individual or mixture of pesticides were studied, with a particular focus on the potential separation of individual pesticides and on the recyclability of the CPE method. In optimal CPE conditions, a quantitative extraction for three of the four pesticides was obtained, with recovery percentages of 95.6%, 98.7%, 99.0%, and 100.0% for imazamox, propoxycarbazone, 2,4-D, and 4-CPA, respectively. After the back-extraction step, separated pesticides were recovered in fresh aqueous mobile phase. The recyclability studies showed that the extraction/back-extraction process can be performed at least four times while maintaining a quantitative extraction.

Binary Solvents with Ethanol for Effective Bitumen Displacement at Solvent/Mineral Interfaces

Displacements of bitumen from silica surfaces were studied using various solvents and binary mixtures of ethanol. It was found that single-component solvents, including water, toluene, cyclohexane, and ethanol, were not able to completely remove bitumen on silica. However, adding 5% ethanol to toluene greatly enhanced its ability to displace bitumen from the silica surface. Surface vibrational spectra obtained by sum frequency generation vibrational spectroscopy showed that no trace of bitumen could be detected on silica after treatment with the 5% ethanol–toluene mixture. Similar effects were observed for cyclohexane with 10% ethanol. The results suggested that binary solutions with amphiphilic components, such as ethanol, are effective solvents for release of bitumen from the mineral surface. This expectation was confirmed by batch extraction experiments on Athabasca oil sands samples using cyclohexane–ethanol solutions.

Extraction of Lead, Cadmium and Nickel from Contaminated Soil Using Acetic Acid

The accumulation of heavy metals in soil is a serious environmental problem. It is well known that heavy metals have an affinity for different compartments of soil. The risk associated with the presence of metals in soil is the ability of their transfer in water or plants. In the present research, batch extraction experiments were conducted using acetic acid (AA) as an extractant solution at various concentrations and contact times to determine the best conditions of soil washing process to achieve high heavy metal removal efficiencies. AA was investigated for its applicability for the removal of lead, cadmium and nickel from soil. Batch soil washing experiments were performed on 1.0 g portions of the spiked soil using different concentrations (0.001, 0.005, 0.01, 0.05, and 0.1 mol/L) of AA (CH3COOH) with solid: liquid ratio of 1:10. The results showed that AA extracted greater Pb than Cd and Ni. The extraction was carried out with shaking times from 15 to 180 min. The removal percentage of Pb varies from 42.2%-100% and Cd from 5.2%-31.1% with increasing concentration of AA, while the removal efficiency of Ni was not exceeded about 1%. Comparing with Pb and Cd, the removal efficiency of Ni was very low; this means that the solubility of Ni in AA was very low. It was found that 0.1 mol/L AA for soil washing was effective in removing absorbed Pb from contaminated soil (100% efficiency) at time 15 min. While the efficiency reaching 100% with washing solution of 0.05 and 0.01 mol/L at times 120 and 180 min, respectively. The efficiencies of Cd and Ni extraction were improved when 1 mol/L of AA solution was used (41.3% to 70.6% for Cd and 16.3% to 23.3% for Ni).

Stability of Prussian Blue in Soils of a Former Manufactured Gas Plant Site

Soil contamination with iron-cyanide complexes is a common problem at former manufactured gas plant (MGP) sites. Dissolution of the cyanide, from Prussian Blue (ferric ferrocyanide), creates an environmental hazard, whereas the risk of groundwater contamination depends on the stability of dissolved iron–cyanide complexes. Lack of a standard leaching method to determine the water-soluble (plant-available) cyanide fraction generates potential limitations for implementing remediation strategies like phytoremediation. Applicability of neutral solution extraction to determine the water-soluble cyanide fraction and the stability of Prussian Blue in surface and near-surface soils of an MGP site in Cottbus, undersaturated and unsaturated water conditions, was studied in column leaching and batch extraction experiments. MGP soils used in the long-term tests varied according to the pH (5.0–7.7) and the total cyanide content (40–1718 mg kg−1). Column leaching, after four months of percolation, still yielded effluent concentrations exceeding the German drinking water limit (> 50 μg L−1) and the solubility of Prussian Blue reported in the literature (< 1 mg L−1) from both alkaline and acidic soils. Long-term (1344 h) extraction of MGP soils with distilled water was sufficient to dissolve 97% of the total cyanide from the slightly alkaline soils and up to 78% from the acidic soils. Both experiments revealed that dissolution of ferric ferrocyanide under circum-neutral pH and oxic water conditions is a function of time, where the released amount is dependent on the soil pH and total cyanide content. Unexpectedly high and continuous solubility of Prussian Blue, both in acidic and slightly alkaline MGP soils, implies the need to introduce an additional cyanide fraction (“readily soluble fraction”) to improve and specify cyanide leaching methods. Long-term extraction of cyanide-contaminated soil in neutral solution seems to be a promising approach to evaluate the potential hazard of groundwater pollution at the MGP sites.

Adsorption-Desorption of Lead and Tin in Soils

The fate of heavy metals, such as Pb, in the soil-water environment is significant in the assessment of their potential mobility and toxicity in the ecosystem. In this study, adsorption batch and sequential extraction experiments were carried out to assess the retention and reactivity of Sn and Pb in soils. Isotherm results exhibited highly nonlinear sorption for both heavy metals. Lead isotherms indicated a Freundlich exponent parameter b of 0.204 and 0.249 for Windsor and Olivier soils, respectively. The respective values for Sn were greater than 1 (2.46 and 3.72), which implies irreversible sorption. Moreover, Sn was completely sorbed, indicative of strong irreversible retention where more than 99% of the added Sn was retained in both soils. No Sn release after 30 days of desorption was detected. The presence of Sn resulted in reducing sorption of Pb by both soils, as evidenced by the decrease in their maximum sorption capacity; whereas, Pb exhibited kinetic behavior where 3 to 15% and 13 to 28% of Pb were released for Windsor and Olivier soils, respectively, during desorption. The use of a second-order two-site model that accounts for nonlinear equilibrium and kinetic reactions was capable of describing the kinetic behavior of Pb during adsorption and desorption in both Windsor and Olivier soils. Sequential extraction results revealed that the most susceptible Pb fraction for release was highest corresponding to highest Pb input concentrations. This concentration-dependent release is consistent with the observed strong nonlinearity of Pb retention and implies that mobility of Pb tends to increase as the input Pb concentration is elevated.

Determination of weight distribution ratios of Pa(V) and Np(V) with some extraction chromatography resins and the AG1-X8 resin

Literature data on distribution ratios (Dw) of Np(V) and Pa(V) for the AG1-X8 resin are scarce whereas those related on resin capacity factors (k′) values for TEVA, TRU and U/TEVA resins are absent. Therefore, batch extraction experiments for Pa(V) and Np(V) from HCl and HNO3 media were realized, at tracer scale, with AG1-X8 and EIChroM resins (TEVA, TRU and U/TEVA). Based on the new Dw and k′ values obtained in this study, a new protocol for Pa/Np separation has been developed leading to a better separation factor of 105 and a chemical yield of 97±3% and 99±1% for Pa and Np, respectively. A separation of 231Pa from uranium matrix was successfully tested.

Characterizing the release of cadmium from 13 purple soils by batch leaching tests

Cadmium (Cd), through human activities, has severely accumulated in purple soil. Purple soil is considered as one of the most important types of agricultural soil in Southern China. In this study, we investigated the release of Cd from 13 purple soils with a wide range of total Cd content collected from vegetable fields and forestlands in Sichuan Basin. Soil batch extraction and column leaching experiments were conducted to determine the influence of chemical speciation, soil properties, soil water contact time, and soil/water ratio on the release characteristics of Cd from soil. Results indicate that Cd release was primarily present in exchangeable, carbonate-bound, and organically bound fractions. Moreover, precipitation-induced, long-term saturated conditions enhance the release of Cd from soil to water. Multiple regression analysis also shows that the release of Cd from soil is related to pH level, organic matter amount, and total Cd content in native soil. This finding explains the Cd release variation of 86% and 95% during batch extraction and column leaching experiments, respectively. Finally, this investigation provides a more convenient way of evaluating potential ecological risks of Cd in purple soil by determining the properties of several common soil types.

Synthesis of crown ether functionalized polyacrylamide gel beads and their extraction behaviour for strontium ions

ABSTRACT 4-acrylamidobenzo-18-crown-6(ABCE) functionalized polyacrylamide (PAAm) gel beads have been synthesized using an indigenously developed sedimentation polymerization setup. The extraction of Sr2+ ions by ABCE functionalized PAAm gel beads was monitored by batch extraction experiments in different concentrations of nitric acid and sodium nitrate solutions. With the aid of atomic absorption spectroscopy (AAS), the concentration of Sr2+ ions in aqueous phase before and after extraction was measured. In nitric acid, the extraction efficiency is found to be high (> 80%) when the number of hydrogen ions in aqueous phase is less than that of ABCE molecules attached to hydrogel backbone. A sudden drop in extraction efficiency was observed when the number of hydrogen ions present in the aqueous phase is greater than that of ABCE molecules attached to hydrogel backbone. Our results indicate that the number of hydrogen ions present in the aqueous phase play an important role in deciding the extraction effici...