Removal Of Polyaromatic Hydrocarbons Research Articles

Solar-activated zinc oxide photocatalytic treatment of real oil sands process water: Effect of treatment parameters on naphthenic acids, polyaromatic hydrocarbons and acute toxicity removal

Oil sands process water (OSPW) is an industrial process effluent that contains organic compounds such as naphthenic acids (NAs) and polyaromatic hydrocarbons (PAHs), as well as large quantities of inorganic compounds in its mixture. OSPW requires effective treatment for successful reclamation and water reuse. This study investigated the impact of solar-activated zinc oxide (ZnO) photocatalysis on the degradation and removal of NAs and PAHs in OSPW, as well as the elimination of its acute toxicity. With catalyst particles suspended in the effluent (at 1 g/L) under simulated solar radiation of steady irradiance of ~278 W/m2, more than 99% removal of NAs was achieved after 4 h of treatment, while nearly all PAHs were simultaneously oxidized within the same reaction time. The photocatalytic treatment appeared to selectively convert classical NAs faster than oxidized NAs. Additionally, NAs with higher double-bond equivalents (DBEs) and higher carbon numbers seemed more susceptible to photocatalytic destruction than others. An overall pseudo first-order rate constant of 1.14 × 10−2 min−1, and a fluence-based rate constant of 6.81 × 10−1 m2/MJ were recorded in apparently hydroxyl radicals (OH) and superoxide (O2−) radicals mediated NAs degradation mechanisms. Assessment of the toxicity levels in raw and treated OSPW samples by using Microtox® bioassay indicated that the photocatalytic treatment resulted in ~50% reduction in acute toxicity. Furthermore, we showed that by monitoring the expression levels of key proinflammatory genes using qPCR that treated OSPW significantly reduced the ability of raw OSPW to activate the inflammatory response of immune cells. This indicates that at acute sub-lethal exposure doses, photocatalytic treatment also reduces immunotoxicity. Overall, our results suggest that the ZnO-based photocatalytic degradation of these NAs and PAHs in OSPW could be a significant treatment process aimed at detoxifying OSPW.

Biochar from waste Sterculia foetida and its application as adsorbent for the treatment of PAH compounds: Batch and optimization

Polyaromatic hydrocarbons (PAHs) are organic pollutants with known health hazards and have been reported worldwide in many water sources. The present study reports the easy and green formulation of KOH-modified biochar from Sterculia foetida shells capable of adsorbing acenaphthene and naphthalene from water. To elevate process efficiency, response surface methodology (RSM) was applied to optimize the sorption process. Batch study data were also analysed to understand the process isothermal, thermodynamic and kinetic characteristics. Characterization of the biochar was done using SEM, EDS, BET, FT-IR and XRD. The results display that the formulated biochar was able to remove approximately 92% and 94% of acenaphthene and naphthalene respectively from aqueous solutions. Further the process was found to follow Langmuir and Temkin isotherms and pseudo-second-order kinetics. The thermodynamic study suggested that the adsorption was endothermic and spontaneous in nature. The activation energy of the process suggested that chemical adsorption was the mode of PAH removal.

Comparative evaluation of different bioremediation techniques for crude oil-contaminated soil

The present study aimed to establish, using the bioremediation technique, the most efficient treatment strategy for remediation of a sandy soil that is artificially contaminated with light crude oil. The experiment was conducted for 180 days to monitor the biodegradation of oils and greases (OG’s), aliphatic hydrocarbons (AHs), and polyaromatic hydrocarbons (PAHs). The removal of these compounds was evaluated using three different strategies, the addition of nutrients (III), addition of a biosurfactant produced from Pseudomonas sp. (IV), and the addition of the biosurfactant plus nutrients (V). The remediation strategies were compared with the control containing only soil (I) and the control with natural crude oil attenuation (II). At the end of the study, it was observed that the strategies III and V showed the best OG’s removal rates, i.e., 90.40% and 78.00%, the best AHs removal rates, i.e., 96.82% and 98.35%, and best PAH removal rates, i.e., 83.58% and 72.3% respectively. Based on the above results, it was concluded that the bioestimulation methods are important tools in the remediation of the environment impacted by oil spills. In addition, the study suggests that the knowledge of the native microbiota is important to improve the efficiency of these bioestimulation techniques.

Removal of TPH, UCM, PAHs, and Alk-PAHs in oil-contaminated soil by thermal desorption

Oil-contaminated soils from a former landfill and gas station site in Korea were treated by thermal desorption. The removal efficiencies of the different oil components such as total petroleum hydrocarbons (TPH), polyaromatic hydrocarbons (PAHs), unresolved complex mixtures (UCM), and alkylated PAHs (Alk-PAHs) by thermal desorption were determined. The effects of temperatures (200, 400, and 600 °C) and treatment times (15, 30, 45, and 60 min) on the thermal desorption efficiency were studied. The treatment efficiency increased with increasing temperature from 200 to 400 °C and with increasing treatment time. Almost complete removals of TPH, UCM, PAHs, and Alk-PAHs were observed after 15 min at 400 °C. The treatment temperatures of 400 and 600 °C did not show a significant difference (p-value > 0.05). Overall, this study shows that the different components of oil in the oil-contaminated soils can be treated effectively in a relatively short time by thermal desorption, and such high removal efficiency in a relatively short time for the oil-contaminated soils can be of advantage for the treatment of highly contaminated or weathered soils where biological treatment efficiency is low.

Effect of the oxidation process on the molecular interaction of polyaromatic hydrocarbons (PAH) with carbon nanotubes: Adsorption kinetic and isotherm study

Agglomeration is a major setback in the use of pristine multiwall carbon nanotube for many applications. Therefore, application of hydroxyl functionalized multiwall carbon nanotubes (MWCNT-OH) for the removal of naphthalene and fluorine was investigated and compared with pristine MWCNT for the first time. FTIR, BET, TGA, SEM, and TEM were used to investigate the functional group, microstructure and morphology of MWCNT and MWCNT-OH. The BET results showed more mesoporosity for MWCNT-OH than MWCNT. Batch equilibrium adsorption data were fitted to the Langmuir, Freundlich and Temkin models, of which the Langmuir model exhibited the best fit. The correlation of Langmuir model for naphthalene adsorption on MWCNT-OH was observed to be higher (i.e. R2 = 0.9703 for MWCNT-OH and R2 = 0.5082 for MWCNT) while the correlation for adsorption of flourene is higher for MWCNT (i.e. R2 = 0.998 for MWCNT and R2 = 0.9517 for MWCNT-OH). The maximum adsorption capacity (qe) for MWCNT-OH (57.401 ng/g-356.121 ng/g for naph and 61.235 ng/g - 367.361 ng/g for fluorene) was generally higher and more stable for lower concentration ranges while it is comparable with MWCNT (48.177 ng/g - 354.00 ng/g for naph and 59.635 ng/g- 366.709 ng/g for fluorene) at higher concentration. The qe calculated (344.828 ng/g for naph and 357.143 ng/g for fluorene) using PSO was observed to be much closer to experimental qe (356.121 ng/g for naph and 367.361 ng/g for fluorine) for MWCNT-OH adsorbent than MWCNT (cal qe are 384.615 ng/g for naph and 400.000 ng/g for fluorene; exp qe 354.00 ng/g for naph and 366.709 ng/g for fluorene). The value of boundary layer thickness, is >0, this indicates the reaction process is quite complex and is not solely controlled by the intra-particle diffusion. The results of this study indicate the high potential of the developed MWCNT-OH adsorbent as an efficient and successful material for the removal of carcinogenic PAHs from the water body.

Use of bacterial acc deaminase to increase oil (especially poly aromatic hydrocarbons) phytoremediation efficiency for maize (zea mays) seedlings

ABSTRACTOil presence in soil, as a stressor, reduces phytoremediation efficiency through an increase in the plant stress ethylene. Bacterial 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase, as a plant stress ethylene reducer, was employed to increase oil phytoremediation efficiency. For this purpose, the ability of ACC deaminase-producing Pseudomonas strains to grow in oil-polluted culture media and withstand various concentrations of oil and also their ability to reduce plant stress ethylene and enhance some growth characteristics of maize and finally their effects on increasing phytoremediation efficiency of poly aromatic hydrocarbons (PAHs) in soil were investigated. Based on the results, of tested strains just P9 and P12 were able to perform oil degradation. Increasing oil concentration from 0 to 10% augmented these two strains population, 15.7% and 12.9%, respectively. The maximum increase in maize growth was observed in presence of P12 strain. Results of high-performance liquid chromatography (HPLC) revealed that PAHs phytoremediation efficiency was higher for inoculated seeds than uninoculated. The highest plant growth and PAHs removal percentage (74.9%) from oil-polluted soil was observed in maize inoculated with P12. These results indicate the significance of ACC deaminase producing bacteria in alleviation of plant stress ethylene in oil-polluted soils and increasing phytoremediation efficiency of such soils.

Biodegradation of acenapthene and naphthalene by Pseudomonas mendocina: Process optimization, and toxicity evaluation

Removal of poly aromatic hydrocarbons (PAHs) from waste water is a challenging task due to their hydrophobic and persistent nature. The present study investigated the efficiency of Pseudomonas mendocina for PAH biodegradation. Biodegradation of PAHs acenapthene and naphthalene was studied and the process was optimized with the Central Composite Design (CCD) feature of Response Surface Methodology (RSM). Toxicity analysis of the untreated and bio treated solutions were conducted on a comparative scale using Cicer arietinum (chickpea) in terms of oxidative stress, germination studies and biochemical parameters. Almost 98.8% and 98.6% degradation of acenaphthene and naphthalene respectively by Pseudomonas mendocina was recorded under RSM optimized conditions. Results of the toxicity analysis further indicated that the bio-treated solutions were fit to be reused or discharged, thereby establishing the potential of Pseudomonas mendocina for biodegradation applications in wide scale.

Antibacterial effect of the Trichoderma viride fungi on soil microbiome during PAH's biodegradation

The aim of this study was to evaluate the influence of Trichoderma viride on the metabolic activity and the community dynamics of soil bacteria during polyaromatic hydrocarbons (PAHs) biodegradation. Sixteen PAHs were introduced into soil microcosms mimicking natural conditions to achieve an initial concentration of 2000 mg kg−1 of soil. After 12 months of treatment, the efficiency of PAH removal was of 78% for the microcosms inoculated with a PAH-degrading bacterial consortium designated S3, 64% for those inoculated with the consortium S3 + T. viride, whereas an efficiency of only 47% was achieved in the microcosms inoculated with T. viride alone. Flow cytometry analysis of the bacterial metabolic activities, expressed as the oxidation-reduction potential, allowed differentiating single cells with regard to their metabolic activities. Prior to its introduction in soil microcosms, the consortium S3 consisted of 195 bacterial species which were identified by employing next generation sequencing (MiSeq, Illumina). It has been established that significant changes in the composition of the bacterial community occurred during the biodegradation process when it was carried out in the presence of T. viride. After such treatment only 73 bacterial species were identified from the metabiome, with the dominance of Stenotrophomonas retroflexus (47.46%), Ochrobactrum intermedium (25.83%) and Citrobacter freundii (19.87%). T. viride was able to degrade PAHs; however its presence mainly contributed to modify the bacterial metabiome via antagonistic interactions with the bacteria, which notably reduced the biodegradation efficiency and biodiversity in the microcosms.

Removal of polyaromatic hydrocarbons from waste water by electrocoagulation

In the present study, two important groups of factors were studied; the first one corresponds to the Electrocoagulation (EC) process parameters such as current density, pH, electrolysis time and electrolyte concentration that were investigated in terms of their effects on the removal efficiencies of polyaromatic hydrocarbons, specially β-naphthols. The second group of factors analyses the effect of three different anode geometries on the percentage removal of β-naphthols. The present study achieved the following results: The optimum conditions for the removal of β-naphthols for cell No. 1 and 2 were achieved at current density 20 mA/cm2, initial pH 7 treated volumes 1.5 L, NaCl concentration 1 g/L and temperature 25°C. Meanwhile, the optimum conditions for cell No. 3 achieved at 106 mA/cm2, initial pH = 7, NaCl concentration = 1 g/L and temperature 25°C, treated volume = 0.5 L. The maximum separation efficiency was achieved for cell No. 1 and the lowest for cell No. 2. Key words: PolyaromaticHydrocarbons, β-naphthols, electrocoagulation, waste water treatment.

Synthesis, modification and graft polymerization of magnetic nano particles for PAH removal in contaminated water.

Magnetic nanoparticles (MNPs) were modified with 3-Mercaptopropytrimethoxysiline (MPTMS) and grafted with allyl glycidyl ether for coupling with beta naphtol as a method to form a novel nano-adsorbent to remove two poly aromatic hydrocarbons (PAHs) from contaminated water. The modified MNPs were characterized by transmission electron microscopy, infrared spectroscopy and thermogravimetric analysis. Results showed that the modified MNPs enhanced the process of adsorption. Tests were done on the adsorption capacity of the two PAHs on grafted MNPs; factors applied to the tests were temperature, contact time, pH, salinity and initial concentration of PAHs. Results revealed that adsorption equilibrium was achieved in 10 min, and the maximum adsorption capacity was determined as 4.15 mg/g at pH = 7.0 and 20°C. The equilibrium adsorption data of the two PAHs by the modified MNPs were analyzed by Langmuir, Freundlich and Temkin models. Equilibrium adsorption data was determined from the Langmuir, Freundlich and Temkin constants from tests under conditions of pH = 7 and temperature 20°C. Analysis of the adsorption-desorption process indicated that the modified MNPs had a high level of stability and good reusability. Magnetic separation in these tests was fast and this shows that the modified MNPs have great potential to be used as a new adsorbent for the two PAHs removal from contaminated water in water treatment.

Removal of Poly Aromatic Hydrocarbons (PAHs) from Water: Effect of Nano and Modified Nano-clays as a Flocculation Aid and Adsorbent in Coagulation-flocculation Process

Water treatment process involving simultaneous action of adsorption on different nano and organo-modified nano-clays followed by coagulation-flocculation by alum and poly aluminium chloride (PAC) has been evaluated for the removal of PAHs (naphthalene, acenaphthalene, phenanthrene, fluoranthene, anthracene, and pyrene) from water. When clay minerals along with alum and PAC were used for treatment, 37.4–100.0% removal of PAHs was observed compared to 20–38% removal using normal water treatment process with either alum or alum + PAC. The effectiveness of clay minerals for removal of PAHs followed the order (P < 0.05): halloysitenano-clay (HN-clay) < normal bentonite (NB-clay) < hydrophilic nano-bentonite (HNB-clay) < nano-montmorillonite modified with dimethyl dialkyl amine (DMDA-M-clay) ≈ nano-montmorillonite modified with octadecylamine and aminopropyltriethoxysilane (ODAAPS-M-clay) ≈ nano-montmorillonite modified with octadecylamine (ODA-M-clay) in combination with alum + PAC. The modified treatment process (alum + PAC + clay minerals), where water was initially treated with clays followed by normal process of coagulation (alum + PAC), was found to be the most effective method with maximum removal for ODAAPS-M-clay (97.7–100.0%) which is at par wih ODA-M (97.0–100.0%), and DMDA-M-clay (94.8–100%). The removal of PAHs varied in the order: naphthalene ≈ acenaphthalene > anthracene ≈ pyrene > phenanthrene > fluoranthrene. The treatment combination having the maximum removal capacity was also used eficiently for the removal of PAHs from natural and fortified natural water. This article demonstrated adsorption-coagulation integrated system has the potential to remediate PAHs polluted water.

POTENTIAL OF LACCASE PRODUCED FROM MICROFUNGUS, AUREOBASIDIUM PULLULANS VAR. MELANOGENUM, TO DEGRADE POLY-AROMATIC HYDROCARBONS

Poly-aromatic hydrocarbons (PAHs) are a group of persistent organic pollutants that are resistant to degradation and can remain in the environment for a long time. PAHs are mainly produced as by-products of incomplete combustion, such as from fossil fuel burning, forest fires, coal fires or vehicle emissions. Currently, PAHs increasingly cause major environmental problems because of continuing industrial development. Biodegradation by microbes is the major natural mechanism for PAHs removal from the environment. The main objective of this research was to study the biodegradation of four types of PAHs (naphthalene, anthracene, pyrene and benzo[a]pyrene) by laccase produced from the lipolytic yeast, Aureobasidium pullulans var. melanogenum , screened from Sichang Island (Thailand). The optimal condition for growing A. pullulans var. melanogenum and its laccase production was first evaluated, and revealed that laccase production could be induced with 2 mM guaiacol and 0.5 M CuSO 4 in the yeast malt (YM) growth medium. Laccase was then lyophilized and stored in capsule form at +4oC to maintain enzymatic activity. The subsequent ability to degrade naphthalene, anthracene, pyrene and benzo[a]pyrenewas determined using high performance liquid chromatography. The results revealed that the laccase activity of one capsule (0.16 g) of lyophilized laccase was 711 U mL -1 (4.4 U mg -1 ) and could degrade a mixture of benzo[a]pyrene (37 µg mL -1 ), anthracene (7.5 µg mL -1 ), pyrene (99 µg mL -1 ) and naphthalene (90 µg mL -1 ) by 45.33, 38.16, 25.38 and 24.35% after 48 hours incubation respectively. Furthermore, the result also revealed that laccase (5 g) from A. pullulans can degrade naphthalene and anthracene in soil samples by 51.34 and 85.06% respectively, after incubation for 9 days.

Simultaneous removal of Cu and PAHs from dredged sediments using flotation

Purpose This study addresses the feasibility of a flotation technique, using a lab-scale flotation cell, to simultaneously remove both metals and polyaromatic hydrocarbons (PAHs) from fine sediment fractions (<250 μm) that are potentially contaminated with copper (Cu).

Bioremediation of a tropical clay soil contaminated with diesel oil

The removal of polyaromatic hydrocarbons (PAH) in tropical clay soil contaminated with diesel oil was evaluated. Three bioremediation treatments were used: landfarming (LF), biostimulation (BS) and biostimulation with bioaugmentation (BSBA). The treatment removal efficiency for the total PAHs differed from the efficiencies for the removal of individual PAH compounds. In the case of total PAHs, the removal values obtained at the end of the 129-day experimental period were 87%, 89% and 87% for LF, BS and BSBA, respectively. Thus, the efficiency was not improved by the addition of nutrients and microorganisms. Typically, two distinct phases were observed. A higher removal rate occurred in the first 17 days (P-I) and a lower rate occurred in the last 112 days (P-II). In phase P-I, the zero-order kinetic parameter (μg PAH g−1 soil d−1) values were similar (about 4.6) for all the three treatments. In P-II, values were also similar but much lower (about 0.14). P-I was characterized by a sharp pH decrease to less than 5.0 for the BS and BSBA treatments, while the pH remained near 6.5 for LF. Concerning the 16 individual priority PAH compounds, the results varied depending on the bioremediation treatment used and on the PAH species of interest. In general, compounds with fewer aromatic rings were better removed by BS or BSBA, while those with 4 or more rings were most effectively removed by LF. The biphasic removal behavior was observed only for some compounds. In the case of naphthalene, pyrene, chrysene, benzo[k]fluoranthene and benzo[a]pyrene, removal occurred mostly in the P-I phase. Therefore, the best degradation process for total or individual PAHs should be selected considering the target compounds and the local conditions, such as native microbiota and soil type.

Aerobic biodegradation and inhibition kinetics of poly‐aromatic hydrocarbons (PAHs) in a petrochemical industry wastewater in the presence of biosurfactants

AbstractBACKROUND: In Izmir, Turkey, wastewaters from the petrochemical industry are treated using conventional activated sludge systems. A significant proportion of poly‐aromatic hydrocarbons (PAHs) with high‐molecular weights remains in this treatment system and inhibits the biological activity. Biosurfactants increase PAHs degradation by enhancing the solubility of the petroleum components. The aerobic inhibition kinetics of PAHs has not previously been investigated in the presence of biosurfactants for a real petrochemical industry wastewater.RESULTS: Among the kinetic models used (Monod‐type, zero, first‐order and second‐order) it was found that the Monod kinetic was effective for describing the biodegradation of PAHs in petrochemcal industry wastewater in the presence of three biosurfactants, namely Rhamnolipid (RD), Surfactine (SR) and Emulsan (EM) in an aerobic activated sludge reactor (AASR). The maximum PAH removal rate (Rmax) and specific growth rate of PAH degrading bacteria (µmax) increased, while the half saturation concentration of PAH (Ks) decreased at 15 mg L−1 RD concentration compared with the control without biosurfactant at a sludge retention time (SRT) of 25 days.CONCLUSION: PAH oxidation is typified by competitive inhibition at RD concentrations &gt; 15 mg L−1 resulting in increases in Ks values with PAH accumulation. Low inhibition constant (KID) values reflect difficulties in the metabolizability of PAHs. Metabolite production decreased at RD = 25 mg L−1 in the PAHs indeno (1,2,3‐cd) pyrene (IcdP), flourene (FLN), phenanthrene (PHE) and benzo(a)pyrene (BaP). Copyright © 2011 Society of Chemical Industry

Removal of Poly Aromatic Hydrocarbons and Total Petroleum Hydrocarbon by Using of Bio-Enzyme: a Batch Study

Removal of Poly Aromatic Hydrocarbons and Total Petroleum Hydrocarbon by Using of Bio-Enzyme: a Batch Study

Effect of Ultrasonic Irradiation on the Treatment of Poly-Aromatic Substances (PAHs) from a Petrochemical Industry Wastewater

The effects of sonication time, nitrogen, N2(g), increasing temperature, dissolved oxygen (DO) and titanium dioxide (TiO2) concentrations on the sonodegradation of polyaromatic hydrocarbons (PAHs) in petrochemical wastewaters were investigated. Sonication alone without N2(g), DO and TiO2 provided 80% maximum PAH yields at 2 5°C after 150 min. This PAH yield increased to 89–95% at 60 °C after 150 min sonication. The contribution of DO, N2(g) and TiO2 on the PAH removal was not significant compared to the control. In the presence of HCO3 −, the degradation of hydrophobic PAH dibenz[a,h]anthracene (DahA)was suppressed in the acceleration step of the sonication. Maximum acute toxicity removal was reached by 30 min N2(g) sparging, 4 mg/L DO and by 0.1 mg/L TiO2 after 150 min sonication.

Molasses as a Whole Medium for Biosurfactants Production by Bacillus Strains and Their Application

Two types of biosurfactant (BS)-producing bacteria, Bacillus licheniformis TR7 and Bacillus subtilis SA9, were isolated from mangrove sediment in the south of Thailand. The BS production was done by using only molasses as a whole medium for growth and production. Under optimized conditions, the yields of TR7 and SA9 BS were found to be 3.30 and 3.78g/l, respectively. It could reduce the surface tension of pure water to 28.5 and 29.5mN/m, with the critical micelle concentrations of about 10 and 30mg/l, respectively. Good thermal, pH, and salt stability were exhibited. Both BSs could recover oil more effectively than the two synthetic surfactants. In addition, TR7 and SA9 BS could enhance the solubility of polyaromatic hydrocarbons (PAHs). Thus, these BSs have the potential for the removal of oil and PAHs from the combined contaminated environment and facilitate its bioremediation. These studies indicate that molasses, as a renewable, relatively inexpensive and easily available resource, can be used for important biotechnological processes.

Tratamento de Solo Contaminado com Petróleo Utilizando Tensoativos e Peróxido de Hidrogênio.

O processo de lavagem de solo com substâncias tensoativas, Lauril éter sulfato de sódio (LESS) e Lauril sulfato de sódio (SDS), foi combinado à oxidação química utilizando peróxido de hidrogênio, com vistas à remediação in situ de solo argiloso contaminado com hidrocarbonetos de petróleo. A avaliação da eficiência do processo baseou-se na remoção dos hidrocarbonetos poliaromáticos e na comparação das características físicas e químicas do solo contaminado e não-contaminado oriundos da mesma região. A combinação dessas duas técnicas, lavagem do solo e aplicação de agente oxidante, apresentou-se como processo de remediação eficaz para solos argilosos contaminados com derivados de petróleo em regiões subtropicais.

Removal of polyaromatic hydrocarbons from scrap tires by solvent extraction

This study analyzes polycyclic aromatic hydrocarbon (PAH) compounds released from scrap tires by GC/MS and introduces a simple extraction process at ambient conditions to remove PAHs from scrap tires. The PAH species released from scrap tires included seven PAH compounds with high molecular weight and 4- and 5-aromatic rings and total-PAH content of 159 mg/L. When scrap tires were extracted using hot water (180 °C) for 3 h, the overall removal efficiency was 53%, indicating that PAHs were not adequately removed by this method. However, using organic solvents, the overall PAH removal efficiency improved to 82% for propionic acid and 70% for acetic acid, because the mass transfer of PAHs within scrap tires increases with decreasing dielectric constant. The PAH removal efficiency was dependent on solvent type and temperature.