Liquid-liquid Extraction System Research Articles

Exploring nematicidal biomolecules from Xenorhabdus nematophila as a novel source for Meloidogyne incognita management

Attempts were made to evaluate the purified bioactive compounds of Xenorhabdus nematophila against Meloidogyne incognita. In order to extract the purified compounds, a solid-supported liquid-liquid extraction system with a flow rate (1 mL/min) was used to purify bioactive molecules. Compounds were individually collected concentrated and evaluated against M. incognita. Among 25 fractions the L19 fraction, exhibited 98% inhibition in egg hatching and mortality of juveniles. The biomolecules were identified through Liquid Chromatography- Mass Spectroscopy (LC-MS) technique. To decipher the mode of action of compounds, molecular docking studies were performed with potential protein targets such as acetylcholinesterase, β-1,4-endoglucanase, glutathione S-transferase-1, cytochrome c oxidase, G-protein coupled receptor and Fatty acid and retinol-binding proteins of M. incognita. The results revealed that among eight compounds from the L19 fraction, malonate and pidopidon exhibited greater binding affinity towards the selected protein targets of M. incognita. In vitro studies with malonate and pidopidon against M. incognita showcased a 99% reduction in egg hatching and juvenile mortality. Moreover, greenhouse experiments revealed that malonate compounds not only reduced 94% of the M. incognita population but also enhanced the plant growth parameters in tomato by 60%. Hence the present study stands novel in exploiting the nematicidal compounds from X. nematophila giving limelight to explore pidopidon and malonate as novel nematicidal compounds for the management of M. incognita.

A Coalescing Filter for Liquid-Liquid Separation and Multistage Extraction in Continuous-Flow Chemistry.

Presented here is the design and performance of a coalescing liquid-liquid filter, based on low-cost and readily available meltblown nonwoven substrates for separation of immiscible phases. The performance of the coalescer was determined across three broad classes of fluid mixtures: (i) immiscible organic/aqueous systems, (ii) a surfactant laden organic/aqueous system with modification of the type of emulsion and interfacial surface tension through the addition of sodium chloride, and (iii) a water-acetone/toluene system. The first two classes demonstrated good performance of the equipment in effecting separation, including the separation of a complex emulsion system for which a membrane separator, operating through transport of a preferentially wetting fluid through the membrane, failed entirely. The third system was used to demonstrate the performance of the separator within a multistage liquid-liquid counterflow extraction system. The performance, robust nature, and scalability of coalescing filters should mean that this approach is routinely considered for liquid-liquid separations and extractions within the fine chemical and pharmaceutical industry.

Dibutylamide hydrophobic deep eutectic solvent used for selective extraction of Au(III) from hydrochloric acid medium

The effective and environmentally friendly recovery of gold from secondary resources has recently received increased attention. Hydrophobic deep eutectic solvent (HDES) composed of N,N-di-butylacetamide and 1-decanoic acid was used to construct the liquid-liquid extraction system to extract Au(III) from HCl medium. At first, DSC, TGA, FT-IR, and 1H NMR were used to describe the evidence of internal hydrogen bond interaction. The above evidence was verified in the molecular dynamics study of HDES. Then, a series of optimization experiments were carried out to investigate the extraction behaviors of HDES. Based on the results of optimization experiments, response surface method was used to explore the best experimental conditions and the results showed that HDES extracted 99% Au(III) under 0.56 mol/L HCl, 2.19 mol/L NaCl, and 5.83 mmol/L Au(III), and the maximum loading reached 77.0 mg/g. Further studies on the kinetics and thermodynamics of the extraction were used to propose an ion association mechanism. In addition, using 0.1 mol/L thiourea as the stripping agent, HDES displayed outstanding Au(III) selectivity and maintained the extraction efficiency in tests which involved 5-cycles. Overall, this study provides a green and efficient Au(III) recovery strategy for secondary resources.

Aqueous two-phase systems - versatile and advanced (bio)process engineering tools.

Aqueous two-phase systems (ATPS), also known as Aqueous Biphasic Systems (ABS), have been extensively studied as platforms for the separation and purification of biomolecules and other valuable compounds. These liquid-liquid extraction (LLE) systems have been a tool for biotechnology since its origin (Albertsson, 1950's), recently expanding to exciting fields such as health, biomedicine and material sciences. Due to their biocompatibility, amenability, flexibility, and versatility, ATPS have been applied across various research areas, addressing many challenges associated with conventional methodologies. In this feature article, we first discuss the fundamentals of ATPS and the molecular mechanisms that govern their formation and are crucial for their application. We then explore the most prominent and innovative applications of these systems in downstream processing. Additionally, we provide insights into the design of in situ upstream-downstream integrated platforms, and their use as pre-treatment and analytical tools. The latest advancements in ATPS applications within disruptive bioengineering and biotechnology fields are presented, along with their pioneering use in emerging scientific areas, such as the formation of all-aqueous (water-in-water) emulsions, microfluidic systems, and membrane-free batteries. Overall, this work underscores the transformative potential of ATPS in various branches of science, pinpointing directions for future research to fully explore and maximize ATPS capabilities, overcome existing hurdles, and drive innovation forward.

Insights into water extraction and aggregation mechanisms of malonamide-alkane mixtures.

Structure at the nanoscale in the organic phase of liquid-liquid extraction systems is often tied to separation performance. However, the weak interactions that drive extractant assembly lead to poorly defined structures that are challenging to identify. Here, we investigate the mechanism of water extraction for a malonamide extractant commonly applied to f-element separations. We measure extractant concentration fluctuations in the organic phase with small angle X-ray scattering (SAXS) before and after contact with water at fine increments of extractant concentration, finding no qualitative changes upon water uptake that might suggest significant nanoscopic reorganization of the solution. The critical composition for maximum fluctuation intensity is consistent with small water-extractant adducts. The extractant concentration dependence of water extraction is consistent with a power law close to unity in the low concentration regime, suggesting the formation of 1 : 1 water-extractant adducts as the primary extraction mechanism at low concentration. At higher extractant concentrations, the power law slope increases slightly, which we find is consistent with activity effects modeled using Flory-Huggins theory without introduction of additional extractant-water species. Molecular dynamics simulations are consistent with these findings. The decrease in interfacial tension with increasing extractant concentration shows a narrow plateau region, but it is not correlated with any change in fluctuation or water extraction trends, further suggesting no supramolecular organization such as reverse micellization. This study suggests that water extraction in this system is particularly simple: it relies on a single mechanism at all extractant concentrations, and only slightly enhances the concentration fluctuations characteristic of the dry binary extractant/diluent mixture.

Solubility of di-(2-ethylhexyl)phosphoric acid (D2EHPA) in aqueous electrolyte solutions: Studies relevant to liquid-liquid extraction

Di-(2-ethylhexyl)phosphoric acid (D2EHPA) is an acidic extractant frequently used in solvent extraction for metal refining. Only limited information is available on the amount and type of impurities present in commercially available D2EHPA and their effect on liquid-liquid extraction. In this paper, these impurities were identified and the importance of pre-conditioning the extractant before carrying out extractions is demonstrated. Furthermore, the solubility of D2EHPA in aqueous solutions was investigated as a function of pH, concentration of extractant and anion present in the aqueous phase (chloride, bromide, iodide, sulfate, methanesulfonate, thiocyanate, and nitrate). The density of the organic phases and the sodium and water uptake in the organic phase were determined as a function of the different anions present in the aqueous phase. The type of anion was found not to have a large influence on the solubility of D2EHPA in the aqueous phases. Low concentrations of salt in the aqueous phase or high pH values resulted in significant losses of D2EHPA to the aqueous phase. A very sharp increase in water content in the organic phase was observed around pH 5 (pH 6 for the nitrate system), accompanied by a significant increase in extraction of sodium ions, which explains the observed increase in density of the organic phase, and the tendency to third-phase formation. The results from this fundamental study help to better understand the behavior of liquid-liquid extraction systems in which D2EHPA is used as extractant and can help to prevent third-phase formation and losses of extractant to the aqueous phase. Moreover, the impurities present in commercially available D2EHPA and their impact on liquid-liquid extraction processes are determined.

Measurements, correlations and thermodynamic modeling of aqueous two-phase systems of polyvinylpyrrolidone (PVP) + sulfate/citrate salts

Aqueous two-phase systems (ATPS) can be described as an alternative to traditional liquid-liquid extraction systems, typically consisting of a polymer and a salt solution. An alternative polymer called polyvinylpyrrolidone (PVP) has emerged as a viable option for ATPS due to its low cost, stability, and potential. This study aimed to investigate the effect of the molecular weight of poly (vinylpyrrolidone) (PVP) (K17, K25, and K30) and the temperature (298.15, 303.15, and 308.15 K) in the system ATPSs composed of PVPs and sodium sulfate/potassium sulfate/tri sodium citrate. The tie-line data were determined by measuring the density (ρ) and refractive index (nD). Moreover, the phase compositions and plait point are investigated for different PVPs molecular weight, temperature, and salt type. In addition, the effect of these parameters on the binodal curve, tie-line length (TLL), and slope of tie line (STL) are analyzed in detail by comparing them with the literature data. The impact of the parameters on the binodal curves was investigated by utilizing the values of the effective excluded volume parameter (EEV) that were calculated from the LLE data. Furthermore, the binodal curves and the tie-line compositions were well-fitted by using some semi-empirical equations. The phase separation ability is enhanced with temperature and PVPs molecular weight. The modified UNIFAC-NRF is used to correlate the liquid-liquid equilibrium data of the studied systems and the optimized binary group interaction parameters were determined.

A continuous process in mixers-settlers for the removal/recovery of chromium in effluents from the tanning industry.

One of the main environmental issues caused by the tanning industry is given by the high concentration of chromium contained on its effluents. The removal of this pollutant has become a technological challenge. To solve this issue, this work proposes a continuous process based on mixers-settlers for the removal of the chromium present in effluents from the tanning industry. The process involves the use of liquid-liquid extraction systems. The study includes the development of isotherms for the removal and stripping, which are further represented through a mathematical model to determine the number of theoretical extraction stages and other operational variables. The results show that a better extraction is achieved in a system with two theoretical stages using Cyanex 272 as extractant, reaching more than 94% of removal of chromium with an extractant concentration of 0.32 mol/L. For stripping, sulfuric acid is used, obtaining a maximum recovery of 94%.

Study on the Equilibria of the Complex Formation of Anionic Chelate of Zn(II) with Tridentate Ligand and the Cation of 3-(2-naphtyl)-2,5-diphenyl-2H-tetrazolium chloride

The equilibria of the complex formation between the anionic chelate of zinc(II) with the tridentate ligand of 4-(2-pyridylazo)-resorcinol (PAR) and the bulky organic tetrazolium cation of 3-(2-naphtyl)-2,5-diphenyl-2Htetrazolium chloride (TV) in the liquid-liquid extraction system Zn(II)‒PAR‒TV‒H2O‒2-methyl-1-propanol was studied by spectrophotometric method. The molar ratio of the reagents was determined by independent methods under the optimum condition for ion-association and for extraction. The validity of Beer’s law was checked and some analytical characteristics were calculated. The constants, describing the association process in aqueous phase and the extraction equilibria, were calculated. Based on this, a reaction scheme, a general formula and a structural formula of the complex were suggested. The zinc(II) cation is six coordinated with the tridentate ligand through the following atoms: the azo nitrogen, the pyridine nitrogen and the oxygen atom from the phenolic group, which is in ortho position relative to the azo group, each of them forming two five-membered chelate rings.

Investigating the effectiveness of the main channel in microfluidic liquid-liquid extraction process

The liquid-liquid extraction method has been one of the most critical chemical engineering processes for many years. The combination of liquid-liquid extraction and microfluidic systems constitutes a significant advancement in this process in recent years. The inherent advantages of microfluidic systems, due to their micro dimensions and the widespread application of liquid-liquid extraction, have made this process more applicable in various industries. This article focuses on microfluidic systems, discussing the effects of changes and modifications made to the main channel of these systems, as well as the resulting improvements in flow type and channel shape, and their applications. The assessment concludes with a discussion of the prospects of this field.

Reinforcement learning based hybrid bond-order coarse-grained interatomic potentials for exploring mesoscale aggregation in liquid-liquid mixtures.

Exploring mesoscopic physical phenomena has always been a challenge for brute-force all-atom molecular dynamics simulations. Although recent advances in computing hardware have improved the accessible length scales, reaching mesoscopic timescales is still a significant bottleneck. Coarse-graining of all-atom models allows robust investigation of mesoscale physics with a reduced spatial and temporal resolution but preserves desired structural features of molecules, unlike continuum-based methods. Here, we present a hybrid bond-order coarse-grained forcefield (HyCG) for modeling mesoscale aggregation phenomena in liquid-liquid mixtures. The intuitive hybrid functional form of the potential offers interpretability to our model, unlike many machine learning based interatomic potentials. We parameterize the potential with the continuous action Monte Carlo Tree Search (cMCTS) algorithm, a reinforcement learning (RL) based global optimizing scheme, using training data from all-atom simulations. The resulting RL-HyCG correctly describes mesoscale critical fluctuations in binary liquid-liquid extraction systems. cMCTS, the RL algorithm, accurately captures the mean behavior of various geometrical properties of the molecule of interest, which were excluded from the training set. The developed potential model along with the RL-based training workflow could be applied to explore a variety of other mesoscale physical phenomena that are typically inaccessible to all-atom molecular dynamics simulations.

Measuring liquid-liquid volume composition in transparent tubing using a linear CMOS sensor

Recent advances in milli- and microscale fluidics have led to the miniaturization of liquid-liquid extraction systems. Carryover is a primary mode of failure in these systems, where unwanted liquid appears at the outlet of the opposite phase. Active monitoring of carryover is key to realizing automation and deployment of such fluidic technologies. In this paper, we present an inexpensive sensor and simple methods of analysis to quantify carryover. The sensor measures the volume composition of immiscible liquids using off-the-shelf tubing, a LED light source, a linear CMOS sensor, and shadowgraphy. Beam4 optical modeling is included to provide insight into this sensor's optical behavior. We report measurements of single and two-phase flows and explore average pixel ratio (signal:background) and menisci counting analyses. As an added benefit, we use average pixel ratio to identify bulk liquids and their constituents, specifically toluene, water, and 0–50 wt% sucrose in water.

Experimental study on the removal of Ca(II) from aqueous solution using a bulk liquid membrane with facilitated transport mechanism

Calcium ion is one of the scale-forming cations in water, as it can readily produce sulfate and carbonate scales. Liquid membranes eliminate the equilibrium constraints of liquid-liquid extraction by integrating extraction and stripping processes into one unit and therefore offer tremendous potential for removing various metal ions from aqueous solutions. In this study, the ability of a bulk liquid membrane (BLM) containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) as a carrier to remove Ca(II) ions from aqueous solutions was explored. D2EHPA showed good efficacy and significantly facilitated transport of Ca(II) through the BLM. The transport mechanism by D2EHPA was investigated using pH measurements, and it was found to be a coupled facilitated mechanism. The effect of key parameters such as solvent type, carrier concentration, concentration of the receiving phase, and transport duration on the extraction and transport efficiencies of Ca(II) were investigated. Results show that the maximum extraction (98.9 ± 0.3%) and transport (97.3 ± 1.2%) were achieved at optimal conditions of 0.05 M D2EHPA in the kerosene as the solvent, 0.1 M HCl, and 24 h. The BLM showed high selective transport for calcium over lithium (5.84). Additionally, the BLM was compared with a liquid-liquid extraction system, and it was shown that the bulk liquid membrane requires less carrier to extract a given amount of Ca(II).

Development of two fully automated quick, easy, cheap, effective, rugged, and safe pretreatment methods for the extraction of psychotropic drugs from whole blood samples.

Quick, easy, cheap, effective, rugged, and safe extraction strategies are becoming increasingly adopted in various analytical fields to determine drugs in biological specimens. In the present study, we developed two fully automated quick, easy, cheap, effective, rugged, and safe extraction methods based on acetonitrile salting-out assisted liquid-liquid extraction (method 1) and acetonitrile salting-out assisted liquid-liquid extraction followed by dispersive solid-phase extraction (method 2) using a commercially available automated liquid-liquid extraction system. We applied these methods to the extraction of 14 psychotropic drugs (11 benzodiazepines and carbamazepine, quetiapine, and zolpidem) from whole blood samples. Both methods prior to liquid chromatography-tandem mass spectrometry analysis exhibited high linearity of calibration curves (correlation coefficients,>0.9997), ppt level detection sensitivities, and satisfactory precisions (< 8.6% relative standard deviation), accuracies (within±16% relative error), and matrix effects (81-111%). Method 1 provided higher recovery rates (80-91%) than method 2 (72-86%), whereas method 2 provided higher detection sensitivities (limits of detection, 0.003-0.094ng/mL) than method 1 (0.025-0.47ng/mL) owing to the effectiveness of its dispersive solid-phase extraction cleanup step. These fully automated extraction methods realize reliable, labor-saving, user-friendly, and hygienic extraction of target analytes from whole blood samples.

Microfluidic solvent extraction of no-carrier-added 64Cu from irradiated Zn target for radiopharmaceutical preparation

Microfluidics based liquid-liquid extraction is emerging as an enabling and powerful technology in radiochemical separations of medically important radioisotopes. In this study, we report the production of high specific activity 64Cu via 64Zn (n, p) 64Cu reaction in a research reactor. A microfluidic continuous flow liquid-liquid extraction system based on the use of dithizone as extractant was developed for efficient separation of miniscule quantity of 64Cu (in ng level) from bulk irradiated Zn target (in g level). The extraction process is completely selective for 64Cu, which could subsequently be retrieved in the desired medium for preparation of radiopharmaceuticals. The overall yield of 64Cu after the separation process was > 85 % and it was obtained with adequately high radionuclidic, radiochemical and chemical purities. Additionally, the effective specific activity of radio chemically separated 64Cu was determined to be 12.2 ± 0.8 GBq/µg, which is quite close to that reported for cyclotron produced no-carrier-added (NCA) 64Cu available commercially. The final 64Cu formulation could be effectively used for preparation of a variety of radiopharmaceuticals with high radiolabeling yields. The promising results obtained in this study open the pathway to achieve continuous and efficient recovery of reactor produced NCA 64Cu from the irradiated target using an automated microfluidic setup.

Deterioration effects of SiO2 nanoparticles on the mass transfer in a single drop system with resistance in both phases

In the present study, it has been shown that the very small amount of Nanoparticles(NPs) has very significant effects on mass transfer deterioration. For the first time, the effects of hydrophilic SiO 2 NPs have been investigated in the system with the resistance in both phases (butanol-succinic acid-water. NPs with four-volume concentrations were added to the dispersed phase, and the transient and terminal velocities of drops were reported using an image processing tool. Results showed that the effects of NPs on the transient velocity of circulating /oscillating drops are insignificant. Experimental results also showed that the maximum and average deterioration effects were 54% and 26%, respectively in the presence of NPs. The addition of only 0.0005 vol% of NPs revealed about 20% deteriorating effect, while after the addition of 0.01 vol% of NPs, slight differences were observed. Accumulation of NPs in the interface area and gradual occupation were the main reason for mass transfer reduction, which has been supported by the calculation results in the present study. At the final stage, for the first time, the new overall mass transfer correlation has been proposed based on conjugate mass transfer resistance. This general form of correlation can be used for any liquid-liquid extraction (LLE) system with the dominant mass transfer resistance in the two phases in the presence of NPs. • Investigation of hydrophilic NPs effects on the mass transfer in systems with the resistance in both phases • Reporting the mass transfer deterioration of about 20% in the presence of 0.0005 vol% of NPs • Proposing a general form of mass transfer correlation for systems with resistance in both phases • confirmation of experimental findings with the calculation results

Highly stable macro-porous N-donor CyMe4-BTPhen/SiO2-P adsorbent for efficient selective extraction of actinides from HLLW: An experimental, mechanism, theoretical study

2,9-bis(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-1,2,4-benzotriazin-3-yl)-1,10-phenanthroline (CyMe4-BTPhen) is one of the most prospective ligands for selective separation of trivalent actinides from high level liquid waste (HLLW). To address its low solubility and irradiation resistance in liquid-liquid extraction systems, herein it was loaded into a porous silica-polymer carrier SiO2-P by vacuum impregnation technique to obtain a high loading rate macro-porous adsorbent CyMe4-BTPhen/SiO2-P with CyMe4-BTPhen as high as 30.48 wt%. BET, SEM, XRD, FT-IR and TOC analysis proved the stable macro-porous CyMe4-BTPhen/SiO2-P was successfully prepared. It exhibited high adsorption efficiency (>98 %) towards trace amount of radioactive 241Am(III) in a broad acidity range of 0.01–4 M nitric acid solutions in less than 5 min, which was even up to 99.5 % in 1–2 M HNO3 solution. Highly efficient separation between Am(III) and Eu(III) was achieved with the separation factor SFAm/Eu up to 123 in 4 M HNO3 solution. The kinetic and adsorption isotherm of Eu(III) are in good agreement with pseudo-second-order kinetic and Langmuir models, respectively. FT-IR and XPS analysis reveal that the complexation mechanism involves the immediate coordination of Eu(III) to N in phenanthroline group and triazine ring. Coordination behavior was further studied by UV titration that the ligand and Nd formed a 2:1 complex in acetonitrile solution. MBO analysis indicated that the Am-N bond in the complex has a shorter bond length and more covalent properties than the Eu-N bond. Meanwhile, thermodynamic results indicate that the ligand binding to Am(III) has a lower Gibbs free energy than that of Eu(III), which all reveal the reasons for the preferential bonding of the ligand to Am(III). In a word, CyMe4-BTPhen/SiO2-P proves to be a very promising adsorbent for separation minor actinides from HLLW.

Simultaneous Determination of Benzo(a)pyrene, Benzo(a)anthracene, Benzo( b)fluoranthene, and Chrysene in Tocotrienol Concentrates Using Dual Solid-phase Extraction and Gas Chromatography-Mass Spectrometry

Background: Polyaromatic hydrocarbons (PAHs) are a class of toxic compounds commonly found in edible vegetable oils as a result of contamination through food processing. Among the wide variety of PAHs existing in edible oils, benzo(a)pyrene (BAP), benzo(a)anthracene (BAA), benzo( b)fluoranthene (BBF), and chrysene (CHR) are commonly monitored due to their toxicity, carcinogenic and teratogenic properties. Materials and Methods: In this context, we described a combination of liquid-liquid extraction and dual cartridge solid-phase extraction (dSPE) system for the extraction of BAP, BAA, BBF, and CHR in palm oil derived tocotrienol rich fraction (T3RF), followed by their analysis using GC-MS operating in selected ion monitoring mode (SIM). Results: The separation was effected using a DB-5HT column (30 m × 0.25 mm × 0.25 μm) that can operate at a high temperature limit of 400 °C, which enables the separation of the PAHs in &lt; 28 min. The calibration curves were correlated within the range of 1.5-25 μg/ L, with detection limits (S/N: 3.3) of 0.48-1.35 μg/L, and relative standard deviations of ≤ 0.07% and ≤ 6.85% were achieved for intra-day retention times and peak areas. Conclusion: The proposed sample preparation and GC-SIM workflow greatly reduces interference caused by tocotrienol homologues and enables the quantitative determination of BAP, BAA, BBF, and CHR in T3RF and palm fatty acid distillates.

Organic Compound Composition in Sachet and Bottled Water Portable Produced in Southwest Ado Ekiti, Nigeria

Organic pollutants are pollutants that are organic in nature, basically containing carbon covalently bonded with other elements. They are known to be toxic or carcinogenic in nature. Their presence in water in large quantity causes considerable and widespread concern. Ten water samples -sachets and bottles, were bought from different potable water producing plants in Ado-Ekiti environs. By using a separatory funnel with liquid-liquid extraction system of 50mL:50mL n-Hexane: Dichloromethane, organic contaminants were extracted from the water samples. These samples were analyzed using ultra violet-visible spectrophotometry, which determined that the wavelength of maximum absorption (λmax) of the organic compounds present in all the water samples was 222 nm. These organic compounds were identified using Gas Chromatography-Mass Spectrometry (GC-MS). The composite water sample obtained from the sachet water revealed sixteen (16) organic compounds, while ten (10) were found in the bottled water composite sample. The common organic compounds found in both the sachet and bottled waters are Neophytadiene, Hexadecanoic acid, Eicosadiene, Cyclotrisiloxane, and Tetrasiloxane. Other organic compounds found only in the composite bottled water samples are: Dodecanoic acid, Octadecadienoic acid, Octadecenoic, Methyl stearate, Benzisothiazol-3-amine, and Arsenous acid. The presence of Arsenous acid is quite worrisome, especially when found in bottled water that most elites in the society drinks. In the composite sachet water sample, other organic compounds found include Copaene, Cubebene, Caryophyllene, Humulene, Naphthalene, Caryophyllene oxide, Tetradecyne, Caffeine, Methyl Hexadecenoic acid, Hexadec-9-enoate, p-Camhorene, Octadecatrienenoic acid, Supraene, and HexamethylCyclotrisiloxane. In general, most of these organic compounds have plant origin but their presence in potable water is undesirable and therefore regarded as contaminants and harmful. The water producing plants need to incorporate effective organic purification systems to remove these organic compounds, which are harmful contaminants from the drinking waters.

Polycyclic aromatic hydrocarbons in harvested rainwater in Warri and Agbarho, Nigeria

ABSTRACT. The aim of this research was to provide an overview of current knowledge, by assessing the possible contamination sources of harvested rainwater by polycyclic aromatic hydrocarbons (PAHs), its effects and possible human health risk assessment. Random sampling technique was used to collect eight rainwater samples from different roofing materials made from (asbestos, zinc, aluminium and thatch) in Warri and Agbarho (AGB). The samples were extracted using a liquid-liquid extraction (LLE) system according to the established procedures of United States Environmental Public Agency (USEPA). Under the optimized conditions, the ranges of extraction recoveries and solid-phase extraction (SPE) clean-up of the PAHs in the harvested rainwater were in the range of 71-90%. Gas chromatography-mass spectrometry (GC-MS) was used for the determination of the sixteen priority PAHs in the samples. The total concentration of PAHs for each of the roof types in Warri Refinery Petrochemical Company (WRPC) are: 0.036±0.012, 0.047±0.020, 0.045±0.018 and 0.0023±0.008 ppm for aluminium, zinc, asbestos and thatch roof, respectively. In addition, total concentration of PAHs for each of the roof types in AGB are: 0.046±0.020, 0.024±0.009, 0.023±0.008 and 0.021±0.007 ppm for aluminium, zinc, asbestos and thatch roof. The PAHs analysed exceeded the United States environmental protection agency (USEPA) standards of contamination.&#x0D; &#x0D; KEY WORDS: AGB, GC-MS, Harvested Rainwater, LLE, PAHs, WRPC&#x0D; Bull. Chem. Soc. Ethiop. 2022, 36(4), 779-789. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v36i4.5