Extraction Of Amines Research Articles

Enhanced selective extraction of biogenic amines using carboxyl-functionalized SBA-15 and SBA-16 mesoporous silica

Enhanced selective extraction of biogenic amines using carboxyl-functionalized SBA-15 and SBA-16 mesoporous silica

A green deep eutectic solvent-based aqueous two-phase system for the extraction of heterocyclic aromatic amines from marinating juice

A green deep eutectic solvent-based aqueous two-phase system for the extraction of heterocyclic aromatic amines from marinating juice

Magnetic Graphene Oxide Modified with MOF-199 for Efficient Extraction of Aromatic Amines from Water Samples for Their Determination with Gas Chromatography

A metal–organic framework (MOF-199) nanocomposite was coated on magnetic graphene oxide (MGO) as a sorbent (MGO/MOF-199) and used for the isolation of aromatic amines by magnetic solid-phase extraction (MSPE). The analytes subsequently determined using gas chromatography with a flame ionization detector (GC-FID). The sorbent mass, desorption solvent, extraction time, desorption time, and pH were optimized. The calibration plots demonstrate linear ranges from 0.1 to 500 ng mL−1 with correlation coefficients from 0.9908 to 0.9939. The limits of detection (LOD) were between 0.03 and 0.1 ng mL−1. To evaluate the repeatability, relative standard deviations (RSD) were evaluated for 0.1, 10, and 100 ng mL−1 of the aromatic amines, yielding values from 3.2% to 4.5%. The developed method was employed to extract aromatic amines from tap water, seawater, and spring water. The relative recoveries were from 97.2% to 99.9%.

COSMO-RS screening of organic mixtures for membrane extraction of aromatic amines: TOPO-based mixtures as promising solvents

Aromatic amines are crucial in pharmaceuticals, but their synthesis is challenging due to unfavorable reaction equilibria and the use of costly, environmentally unfriendly methods. This study presents a membrane extraction (ME) process for in situ product removal (ISPR) of aromatic amines. Using a supported liquid membrane (SLM), -methylbenzylamine (MBA) and 1-methyl-3-phenylpropylamine (MPPA) were separated from isopropyl amine (IPA). COSMO-RS was employed to screen over 200 organic mixtures, identifying twelve mixtures based on trioctylphosphine oxide (TOPO), lidocaine, and menthol as solvent candidates, due to their hydrophobicity. These mixtures were analysed for critical solvent properties including density, viscosity, hydrophobicity, and hydrogen bonding interactions. ME tests showed TOPO-thymol had the highest solvent residual and selectivity. Moreover, TOPO-thymol demonstrated solute fluxes of 9.0±3.0 g/(m2 h) for MBA, 16.5±5.4 g/(m2 h) for MPPA, and 0.7±0.3 g/(m2 h) for IPA, with selectivity values of 12.4±0.8 for MBA/IPA and 22.8±1.4 for MPPA/IPA. Compared to undecane, which had lower selectivity values of 6.9±0.8 for MBA/IPA and 10.1±1.3 for MPPA/IPA, TOPO-thymol showed superior selectivity, indicating its promise as an extractant for ME applications.

Simultaneous extraction and derivatization of biogenic amines during in-situ deep eutectic solvent-based liquid phase extraction from Doogh samples prior to HPLC analysis

A simple and efficient microwave-assisted extraction method using deep eutectic solvent was developed for the simultaneous analysis of four biogenic amines (putrescine, tyramine, cadaverine and histamine) in Doogh (yogurt-based beverage) samples. Important parameters like precipitating agent volume, vortexing time, microwave power, and exposure time were optimized. Zinc sulfate was utilized for proteins precipitation prior to extraction of analytes with the deep eutectic solvent choline chloride/p-anisidine. The analytes were derivatized with dansyl chloride and analyzed by HPLC-DAD. The method showed good linearity (r2 ≥ 0.994) over wide ranges with low limits of detection (0.52–0.78 ng mL−1) and quantification (1.7–2.5 ng mL−1). Extraction recoveries ranged from 68–72 % and relative standard ≤8.1 %. Negligible matrix effects were observed. When the method was applied to real Doogh samples and several biogenic amines were detected. The developed method provided reliable results in terms of sensitivity and selectivity.

Development of heat-assisted in-situ solvent formation liquid phase microextraction followed by derivatization for the simultaneous extraction of aliphatic amines from wastewater samples prior to gas chromatography-mass spectrometry

Herein, a cost-effective, rapid, and selective liquid phase microextraction procedure has been developed for the extraction of some aliphatic amines from sewage samples. The method was based on in-situ formation of chloroform as an extraction solvent into the sample solution followed by derivatization by butylchloroformate prior to gas chromatography- mass spectrometry. Chloroform is formed by the reaction of chloral hydrate and sodium hydroxide. The extraction procedure was accelerated by heating. Also heating decreases chloroform solubility in aqueous solution. To improve the analytical signals, derivatization of the analytes is done by butylchloroformate. The effect of major parameters on the extraction efficiency were studied and optimized. Under the optimized conditions, enrichment factor and extraction recovery were in the ranges of 259–296 and 78–89 %, respectively. Low limits of detection (0.08–0.12 ng mL−1) and quantification (0.28–0.41 ng mL−1), wide linear ranges, and relative standard deviations less than 6 % for intra −and inter-day precisions were acceptable. Lastly, the mentioned method was successfully performed to determine aliphatic amines in wastewater samples.

New Trends for Hydrogen Sulfide Scavenging Using Natural Compounds as Biogenic Amines.

Hydrogen sulfide (H2S) mitigation through the use of additives in a laboratory-scale evaluation of steam injection in batch reactors was studied using extra heavy crude oil. For this purpose, additives based on biogenic amines from a fishing effluent were used with methanol and ethanol as solvents in a previous extraction of industrial fishmeal waste. The study of the extracts using high-performance liquid chromatography (HPLC) permitted the determination that the methanol-based extract with 48 h of decomposition had the highest biogenic amine content, totaling 1472 ppm. In addition, methanol extractions were more efficient, with an average biogenic amine content of 592 ppm. Subsequent evaluations were carried out for sand/oil/water/scavenging additive systems, where solutions of commercial organic compounds, analytical-grade histamine, and biogenic amine extracts were used. These evaluations were performed at a constant temperature of 247 °C and under an initial pressurization of methane gas of 215 psig, with a reaction time of 24 h. Characterization of gaseous effluents for each system allowed us to determine that the methods in which biogenic amine extracts were used with methanol were more effective in H2S scavenging because they had the lowest gas concentration at the end of the reaction time. Within this group, the most effective was the C1 extract, with a H2S reduction from 1700 to 150 ppm, representing 91% removal. The biogenic amine family produced by decomposition in conjunction with histamine has a synergistic effect in tests under vapor injection conditions when comparing the results with analytical-grade histamine solution-based additives and commercial additives. This study shows that using steam injection technology to use biogenic amines in H2S mitigation is feasible.

Solvent Extraction of Iridium(III) from Hydrochloric Acid Solutions with Amine Extractants

Solvent Extraction of Iridium(III) from Hydrochloric Acid Solutions with Amine Extractants

Extraction of zinc from spent pickle liquor using primary amine extraction system

Spent pickle liquor is a hazardous liquid containing zinc and iron ions, and other environmentally harmful elements. Therefore, its discharge is prohibited because of ecological and environmental issues. A novel cleaning process for the recovery of Zn from spent pickle liquor using solvent extraction was proposed. The extraction system comprised a secondary carbon primary amine (N1923), isooctanol, and sulfonated kerosene. Spent pickle liquor after ultrasonic enhanced reduction pretreatment was studied experimentally, and effective parameters such as the extractant concentration, organic phase composition, and phase ratio (O/A) on the extraction were investigated. The extractant N1923 was found to selectively extract Zn(II) from the spent pickle liquor and retain Fe(II) in the raffinate. The concentration of Zn(II) ions in raffinate obtained using three-stage counter-current extraction was only 0.01 g/L. The raffinate could be further used to prepare an iron salt water purifier. A solution of H2SO4 was used to strip Zn from the loaded organic phase, yielding a Zn-rich solution containing 5.39 mol/L Zn, which could be used to prepare ZnO. The unloaded organic phase was recycled, and no emulsification or scale accumulation was observed during the process. The structure of the extracted complex was determined using the slope and loading capacity methods, and combined with FT-IR analysis. The main reaction that occurs during the extraction process is the anion-exchange reaction, with a stoichiometric ratio of N1923 to zinc ions of 1, resulting in an extracted complex of RNH3ZnCl3. Overall, the process provided an efficient, low-consumption, convenient, safe, and sustainable method for recovering Zn from spent pickle liquor and laying the foundation for industrial applications.

Optimal Extraction and Separation of Europium and Samarium from Nitrate Medium Using Binary Mixture of Cyanex 572 and Tertiary Amine Extractants

ABSTRACT Extraction and separation of rare-earth elements (Eu(III) and Sm(III)) from nitrate solutions were studied using Cyanex 572 and Alamine 336 type extractants, as well as their binary mixtures in kerosene. Separate studies were carried out on the parameters that influence the extraction process. According to the slope analysis method, the composition of extracted species in the organic phase is [MNO3A2(HA)2][R3NH.NO3]2(Org). The mixture loading capacity towards Eu(III) and Sm(III), as well as the stripping of their loads from the organic phases, were also tested. After being treated with a NaOH solution, the stripped binary mixture was regenerated. The FT-IR spectra of the binary mixture organic phase, the organic phase loaded with metals, the stripped organic phase, and the regenerated organic phase were identified and compared. The separation method is based on a combined reduction-precipitation process in which europium is reduced to its bivalent state by commercial zinc metal, followed by the precipitation of its sparingly soluble europous sulphate. The developed method was used to separate a synthetic mixture of Eu(III) and Sm(III) from an analogous solution in nitrate medium to that expected from spent nuclear fuel leach liquor. Extraction and separation processes for Eu(III) and Sm(III) were detailed in a flowchart.

Determination of biogenic amines in dry fish samples (Scomber scombrus)

The research focuses on the comprehensive analysis and quantification of biogenic amines in dry fish samples, an essential aspect of food safety and quality. To achieve accurate and reliable results, a robust analytical method was adopted using high-performance liquid chromatography (HPLC) equipped with DAD UV/ Vis detector. The extraction of biogenic amines from dry fish samples was optimized to ensure maximum recovery, and suitable derivatization techniques were employed to enhance the detectability of these compounds. Nine (9) biogenic amines; Histamine (HIS), Cadaverine (CAD), Tyramine (TYM), Ethylamine (ETH), Methylamine (MET), Putrescine (PUT), Typtamine (TYP), Agmatine (AGM) and Isoamlamine (ISO) were analyzed in the fish samples. The correctness and repeatability of the method were assessed by performing replicate analyses (n = 3) for two samples of dried fish from Mile 2 and Choba sites respectively. The detection levels of biogenic amines in the dried fish samples ranged from 1.mg/kg to 1.70 mg/kg for agmatine; from 0.03 mg/kg to 0.04 mg/kg for cadaverine; from 5.52 mg/kg to 5.60 mg/kg for Ethylamine; from 0.42 to 0.48mg/kg for histamine; from 7.15 mg/kg to 7.16 mg/kg for Methylamine; from 5.13 mg/kg to 5.29 mg/kg for Isoamalamine; from 0.84 mg/kg to 0.90 mg/kg for Putrescine; from 2.70 mg/kg to 2.90 mg/kg for tryptamine and from 4.26 mg/kg to 4.44 mg/kg for tyramine across all sample locations respectively. The maximum histamine, Cadaverine and Agmatine detection levels were significantly less than other bioamines detected. Nine biogenic amines were detected where Cadaverine tends to be the lowest and high Methylamine concentration was recorded in both samples, though less than those of the regulation and recommendation set by the EU regulations and national standards for fish products.

Carboxyl-functionalized covalent organic frameworks for the efficient adsorption of foodborne heterocyclic aromatic amines

The development of sorbents with high sensitivity and specificity for the effective extraction and assessment of carcinogenic heterocyclic aromatic amines (HAAs) in thermally processed foods is of utmost significance for food safety monitoring. Herein, we report the design and synthesis of a carboxyl-functionalized covalent organic framework (COF), TpPa-(COOH)2, through the regulation of carboxyl modification and crystallinity. The resulting flower-like TpPa-(COOH)2 exhibited excellent crystallinity and microporosity in an eclipsed stacking structure. Compared to TpPa, the introduction of carboxyl moieties in TpPa-(COOH)2 provided additional binding sites and significantly enhanced adsorption affinity for the 16 target analytes, despite having a smaller BET surface area. The adsorption of HAAs by TpPa-(COOH)2 followed the pseudo-second-order model and exhibited rapid kinetics (10–30 min). The experimental data demonstrated a strong fit with the Freundlich isotherm model, resulting in a maximum adsorption capacity of HAAs ranging from 1.8 to 155.8 mg/g. Additionally, the presence of interfering compounds only caused a slight reduction in both the equilibrium adsorption capacity and HAAs recovery. Notably, TpPa-(COOH)2 maintained its effective adsorption performance even after three adsorption–desorption cycles. Theoretical calculations indicated that the rapid binding of HAAs to TpPa-(COOH)2 could be attributed to the joint effects of electrostatic interaction, π–π interaction, C–H–π interaction, lone pair–π interaction, and hydrogen bonding. This adsorbent exhibits a notable enhancement in both adsorption capacity and mass transfer rates for the adsorption of HAAs, surpassing the performance of the reported adsorbents. This highlights its substantial potential for the precise detection of HAAs within food systems.

Structure Investigation of La, Y, and Nd Complexes in Solvent Extraction Process with Liquid Phosphine Oxide, Phosphinic Acid, and Amine Extractants

The main challenge in separating REEs through hydrometallurgical processes is their chemical similarities. Despite the literature widely presenting the possibilities for organic extractants, there is a lack of evaluation of the structures formed between the REEs and the extractants. The present study aimed to evaluate different extractants (neutral, anionic, and acid extractants) for separating La, Y, and Nd. The extraction efficiencies were evaluated, and the structure investigation was carried out in FT-IR. From the results obtained, it is clear that the extraction order is Alamine 336 <<< Cyanex 272 < Cyanex 923, where both acid extractants were more selective for Y than for La and Nd. The extraction achieved 99% at pH 5.0 in nitric acid media, and a Y/La ratio of 2 and a Y/Nd ratio of 4 using Cyanex 923. The present study also elucidated the organometallic complexation between Cyanex 923 and Cyanex 272 with Y and La, which may improve separation processes to obtain critical metals from primary and secondary sources.

Synthesis, characterization and application of a polyindole coated magnetic porous carbon nanoadsorbent for extraction and determination of toxic aromatic amines

In this research, a polyindole coated magnetic porous carbon (MPC@PIN) nanoadsorbent was synthesized and applied to the extraction of toxic aromatic amines from divers real water. The MPC was derived from MIL-53(Fe) as a metal–organic framework (MOF) source by calcination of the MOF under an inert atmosphere. After that, the functionalization process was performed by the polymerization of indole on the surface of the MPC. The synthesized nanoadsorbent (MPC@PIN) was characterized by various methods such as Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). Separation and determination of the target analytes was performed by HPLC-photodiode array (PDA) detection system. The extraction performance of MIL-53(Fe), MPC, and MPC@PIN was compared toward the target analytes, and the results exhibit the best extraction efficiency for the MPC@PIN. After optimization of the affecting parameters, LODs and linear ranges were 0.05–0.2 µg/L and 0.15–400 µg/L, respectively. Precision (n = 3) of the method as intra-day RSD, and inter-day RSD values were obtained in the range of 3.5–8.2%, and 5.8–12.3%, respectively. Finally, the method applicability was affirmed by analyzing various water samples, satisfactorily. To prepare spiked water samples, a small volume of the AAs standard solution was added to each sample, and then the spiked sample was subjected to the MSPE process.

Isoquinoline alkaloids isolated from Glaucium corniculatum var. corniculatum and Glaucium grandiflorum subsp. refractum var. torquatum with bioactivity studies

Context The genus Glaucium Mill., one of the important Papaveraceae family plants, is rich in isoquinoline alkaloids and distributed worldwide. Objective Isolation and identification of bioactive alkaloids from Glaucium grandiflorum Boiss. & Huet. subsp. refractum (Nabelek) Mory var. torquatum (Cullen) Mory and G. corniculatum (L.) Rudolph var. corniculatum (Aslan 2012), and investigation of their antioxidant and anticholinesterase activities. Materials and methods The aerial parts of each plant were dried, powdered, and percolated with methanol, then each extract was fractionated between 50% aqueous acetic acid and petroleum. Their aqueous acidic layer was adjusted to pH 7–8 with NH4OH and extracted with chloroform, the extract was subjected to CC separation and isolation. Structures of the isolated alkaloids were elucidated by 1D and 2D-NMR and mass spectral analyses. The alkaloid extracts and their pure alkaloids were tested for anti-cholinesterase (AChE and BuChE) and antioxidant (ABTS, CUPRAC, β-carotene linoleic acid tests) activities in vitro. Results Methanol extracts of Glaucium grandiflorum subsp. refractum var. torquatum and G. corniculatum var. corniculatum afforded a novel compound glauciumoline and seven known isoquinoline alkaloids three of which have an aporphine-type and the other five have a protopine-type skeleton. Among them, trans-protopinium (7) and cis-protopinium (8) were isolated from a Glaucium species for the first time. Tertiary amine extracts (TAEs) of both plants showed very strong acetylcholinesterase inhibitory activity. The TAE of the plants also showed strong antioxidant activity while the isolated alkaloids showed no meaningful activity in the anticholinesterase and antioxidant tests. Discussion and conclusions Glaucium species are considered promising therapeutic agents in the treatment of Alzheimer’s disease.

Controllable molecular orientation at the interface and coordination with second hydration-sphere to enhance separation of Pt(IV) and Pd(II) in hydrochloric acid solutions: Mass transfer based separation and molecular dynamics

In conventional liquid-liquid extraction, Pt(IV) and Pd(II) chloride complex anions PtCl62− and PdCl42− in concentrated hydrochloric acid cannot be separated using simple amine extractants according to the ion association mechanism based on the thermodynamic difference in the interaction of their inner sphere coordinated chloride ions with protonated amine. This study exhibits a novel strategy for enhancing the separation of PtCl62− and PdCl42− anions using thin-layer organic membrane-based laminar flow (TOMLF) extraction by controlling the acidified primary amine N1923 (A-N1923) molecular orientation on the surface of concentrated hydrochloric acid with a laminar shear flow. Experiments revealed that the separation selectivity is primarily determined by the interaction of A-N1923 molecules with the outer sphere-bound water molecules around PtCl62− and PdCl42− anions, and is easily controlled by regulating the A-N1923 molecular orientation on the surface of laminar flow. It is a new phenomenon that has not been previously documented. The evolution of A-N1923 molecular orientation and complexation sites induced by laminar shear flow would result in a controllable spatial geometry recognition, therefore promoting or inhibiting the separation of PtCl62− and PdCl42− anions in concentrated hydrochloric acid. This work is expected to provide new insight into the development of hydration-sphere coordination strategies based upon shear-switch laminar flow for controllable host-guest molecule recognition at a flowing liquid-liquid interface.

Selective Separation of 4,4’-Methylenedianiline, Isophoronediamine and 2,4-Toluenediamine from Enzymatic Hydrolysis Solutions of Polyurethane

ABSTRACT The recycling of plastics such as polyurethane (PU) is a current challenge. The continuously increasing production volume and additionally growing end-of-life streams increase the urgency for solutions. Conventional recycling methods such as mechanical and chemical recycling are only economically and/or ecologically suitable to a limited extent. The three-step approach consisting of enzymatic PU decomposition, separation of amines (4,4’-methylenedianiline (MDA), isophoronediamine (IPDA), 2,4-toluenediamine (TDA)) and fermentation of the residual stream is a promising recycling concept. In this study, extraction methods for the separation of MDA and IPDA from an aqueous solution at neutral pH are developed. In addition, the influence of relevant PU hydrolysate components on the amine extraction is investigated. The results show that MDA can be efficiently separated using solvent extraction of 1-octanol. For IPDA separation, a reactive extraction with oleic acid as reactant is developed. The application of these two extraction methods to TDA shows extraction efficiencies of 52% to 86%. The other PU hydrolysate components adipic acid and selected salts have only a minor influence on the extraction efficiency. The diols ethylene glycol and 1,4-butanediol influence the equilibrium pH of IPDA extraction, raising it to higher values. For MDA, no influence of other PU hydrolysate components on the extraction efficiency can be observed. Since amines can have an inhibitory effect on microorganisms, toxicity experiments were carried out to determine the tolerable residual concentration of amines in the raffinate to avoid fermentation inhibition. Growth experiments with Pseudomonas putida KT240 show that MDA has an inhibitory effect at concentrations near the solubility limit, whereas IPDA does not affect growth.

Synergistic Extraction of Ga(III) from Chloride Solution by Mixture of Cyanex 272 and Alamine 336

Aming to select a suitable system for the synergistic solvent extraction of Ga(III), solvent extraction (SX) experiments were carried out by using acidic organo-phosphorous extractants, namely P204, P507 and Cyanex 272, and their mixtures with neutral extractants (TBP, N503) or amine extractants (Alamine 336). Among the studied mixtures, a remarkable synergistic effect for Ga(III) extraction was resulted by the combination of Cyanex 272 and Alamine 336 and the maximal synergistic enhancement coefficient reached 3.11. Compared to the single Cyanex 272, higher equilibrium pH values were observed when mixture of Cyanex 272 and Alamine 336 was employed. The extraction of hydrogen ions by Alamine 336 during the reaction was considered to be responsible for the synergistic extraction, and thus the the extraction of Ga(III) by Cyanex 272 was promoted. Finally, the synergistic extraction stoichiometry of mixture of Cyanex 272 and Alamine 336 for Ga(III) was projected by slope analysis. Ga(OH)A2 was resulted to be the composition of extracted complexes.

Design and manufacture of emulsion liquid membrane based on various amine extractants for separation and extraction of succinic acid from fermentation broth

The aim of this study was to design a new emulsion liquid membrane (ELM) system for the separation of succinic acid from aqueous solutions. The concentration of succinic acid varied from 20 to 60 mmol·L−1. The prepared ELM system includes tributylamine (TBA) as a carrier, commercial kerosene as a solvent, Span 80 as a surfactant, and Na2CO3 as a stripping agent. In order to control the membrane swelling, different values of cyclohexanone were added to the membrane phase. The effect of various empirical variables on the extraction of the succinic acid such as acid concentration in the feed solution, initial feed concentration, carrier concentration, the stirring speed of the extraction, Na2CO3, surfactant, and cyclohexanone concentrations, and treat ratio in the ELM system. The best result was obtained when TBA was used as the carrier. The final acid extraction efficiency was independent of pH variations of the aqueous feed solution. The extraction of succinic acid solution with a concentration of 40 mmol·L−1 was improved by increasing the treat ratio 1:7–1:3, stripping phase concentration 0.5–1.5 mol·L−1, stirring speed 300–500 r·min−1 and cyclohexanone concentration in the membrane phase 1.2–1.6 mol·L−1. No considerable effect on the extraction rate was observed for the carrier concentration in the membrane phase. But, the surfactant concentration in the feed phase showed a dual effect on the extraction efficiency.

Alginate magnetic graphene oxide biocomposite synthesis for removal of aromatic amines from aqueous samples.

In the present work, alginate magnetic graphene oxide biocomposite was synthesized for the removal and extraction of aromatic amines (aniline, p-chloroaniline (PCA), and p-nitroaniline (PNA)) from water samples. The biocomposite was investigated for its physiochemical characteristics such as surface morphology, functional groups, phase determination, and elemental composition. The results revealed that the functional groups of graphene oxide and alginate retained in biocomposite with magnetic properties. The biocomposite was applied to water samples for the removal and extraction of aniline, p-chloroaniline, and p-nitroaniline through adsorption process. The adsorption process was studied under various experimental conditions like time, pH, concentration, dose, and temperature, and all the parameters were optimized. The maximum adsorption capacities at room temperature have an optimum pH = 4 for aniline = 18.39mgg-1, for PCA = 17.13mgg-1, and for PNA = 15.24mgg-1. Kinetic and isotherm models showed that the experimental data is best fitted to pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic study suggested that the adsorption process is exothermic and spontaneous. Ethanol was found to be the best eluent for the extraction of all the three analytes suggested by the extraction study. The maximum percent recoveries from spiked water samples were calculated for aniline = 98.82%, PCA = 96.65%, and PNA = 93.55% which showed that alginate magnetic graphene oxide biocomposite could be a useful and ecofriendly adsorbent for the removal of organic pollutants in water treatment processes.