Utilization of a biosurfactant foam/nanoparticle mixture for treatment of oil pollutants in soil

Oil contamination has become a primary environmental concern due to increased exploration, production, and use. When oil enters the soil, it may attach or adsorb to soil particles and stay in the soil for an extended period, contaminating the soil and surrounding areas. Nanoparticles have been widely used for the treatment of organic pollutants in the soil. Surfactant foam has effectively been employed to remediate various soil contaminants or recover oil compounds. In this research, a mixture of biosurfactant foam/nanoparticle was utilized for remediation of oil-contaminated soil. The results demonstrated that the biosurfactant/nanoparticle mixture and nitrogen gas formed high-quality and stable foams. The foam stability depended on the foam quality, biosurfactant concentration, and nanoparticle dosage. The pressure gradient change in the soil column relied on the flowrate (N₂ gas + surfactant/nanoparticle mixture), foam quality, and biosurfactant concentration. The optimal conditions to obtain good quality and stable foams and high oil removal efficiency involved 1 vol% rhamnolipid, 1 wt% nanoparticle, and 1 mL/min flowrate. Biosurfactant foam/nanoparticle mixture was effectively used to remediate oil-contaminated soil, whereas the highest treatment efficiency was 67%, 59%, and 52% for rhamnolipid biosurfactant foam/nanoparticle, rhamnolipid biosurfactant/nanoparticle, and only rhamnolipid biosurfactant, respectively. The oil removal productivity decreased with the increase of flowrate due to the shorter contact time between the foam mixture and oil droplets. The breakthrough curves of oil pollutants in the soil column also suggested that the foam mixture’s maximum oil treatment efficiency was higher than biosurfactant/nanoparticle suspension and only biosurfactant.

     

Waste Minimization in the Manufacture of Flexible Polyurethane Foams: Quantification of Auxiliary Blowing Agent Volatilization

Experimental investigations were conducted to quantify the volatilization dynamics of blowing agent loss and to examine innovative means to maintain safe worker conditions while simultaneously recovering the auxiliary blowing agent. Methylene chloride-blown polyurethane foams with representative formulations were prepared to determine overall weight loss, auxiliary blowing agent weight loss and foam temperature profiles versus time. Approximately 60 percent of the methylene chloride is lost within the first ten minutes of the process; the residual 40 percent is lost slowly by diffusion over 24 hours. Based on the collected data, a model was developed which predicts tunnel concentrations of methylene chloride as a function of formulation, tunnel length, conveyor speed and air flow. Retrofit of a foam line to isolate the tunnel and drastically reduce exhaust flows will eliminate worker exposure to isocyanates and significantly increase tunnel concentrations of the auxiliary blowing agent. This increase in ambient blowing agent concentration should allow for recovery by conventional means. A project to demonstrate this isolation/concentration/ recovery/recycle strategy is currently underway at a North Carolina foamer.     

固相微萃取-气相色谱法测定饮用水及其水源水中的氯酚

利用固相微萃取(SPME)-气相色谱法(GC)联用技术测定饮用水及其水源水中的氯酚．优化萃取温度、萃取平衡时间、酸度、离子强度等实验条件．所建方法简便、精确,自来水和太湖水中均检测到氯酚。     

Studies on thio-substituted polyurethane foam (T-PUF) as a new efficient separation medium for the removal of inorganic/organic mercury from industrial effluents and solid wastes

Novel thio-substituted flexible polyurethane foam (T-PUF) was synthesised by addition polymerisation of mercaptan with the precursors of an open-cell polyurethane foam, which can be used as a highly selective sorbent for inorganic and organic mercury from complex matrices. The percentage extraction of inorganic mercury was studied at different flow-rates, over a wide pH range at different concentrations ranging from 1 ppm, to 100 ppm. The break-through capacity and total capacity of unmodified and thio-foams were determined for inorganic and organic mercurials. The absorption efficiency of thio-foam was far superior to other sorbent media, such as activated carbon, polymeric ion-exchange resins and reagent-loaded polyurethane foams. It was observed that even at the 1000 ppm level, divalent ions like Cu, Mg, Ca, Zn do not appreciably influence the per cent extraction of inorganic mercury at the 10 ppm level. These matrix levels are the most concentrated ones which are likely to occur, both in local sewage and effluent waters. Further, the efficiency of this foam was sufficiently high at 10-100 ppm levels of Hg, even from 5-10 litres of effluent volumes using 50 g of thio-foam packed into different columns in series. Thio-foams were found to possess excellent abilities to remove and recover mercury even at low levels from industrial effluents and brine mud of chlor-alkali industry after pre-acid extraction. This makes it a highly efficient sorbent for possible application in effluent treatment. Model schemes for the removal and recovery of mercury from industrial effluents and municipal sewage (100-1000 litre) by a dynamic method are proposed and the costs incurred in a full-scale application method are indicated to show that the use of thio-foam could be commercially attractive.     

Closed-Loop Recovery of Site Remediation Gas Phase Contaminants

A novel gas phase treatment system (contaminant absorption and recovery [CAR]) for removal and subsequent recycling of gas phase VOCs from soil vapor extraction/gas stripping systems has been developed. Gas phase removal efficiencies using a packed column contactor exceed 99 percent The VOC-laden absorption fluid is subsequently vacuum-stripped of the VOCs, allowing potential condensation into liquid solvent concentrates. Partition coefficients for trichloroethylene (TCE) in triethylene glycol (TEG) ranged to ca. 5.0 mole fraction gas/mole fraction liquid, indicating a significant capacity for removal from the gas phase. Results of pilot-scale operation indicate favorable removal efficiencies and cost-effective performance in comparison to GAC or thermal destruction processes. System mass transfer coefficient predictions were done, using a variety of mathematical models and compared to experimental results. A modified Mangers and Ponten correlation was found to describe system mass transfer coefficients well. The impact of water carry-over on TCE/TEG partitioning was found to be significant. The standard change in entholpy (ΔH°) and the standard change in volume (ΔV°) values were also calculated, and predictions of temperature and pressure on system performance were evaluated.     

Simultaneous analysis of 50 pesticides in water samples by solid phase extraction and GC-MS

A multiresidue analysis of 50 pesticides has been developed as a rapid screening method for organic contaminants in water samples. Solid phase extraction was accomplished with two adsorbents in a single column. Simultaneous analysis was performed with gas chromatography-mass spectrometry (GC-MS). The limits of detection for each pesticide are at sub-ppb levels. This method was used to check contamination of water from the Adige river (Northern Italy).     

Multicriteria optimisation of a simultaneous supercritical fluid extraction and clean-up procedure for the determination of persistent organohalogenated pollutants in aquaculture samples

A useful tool based on a single-step extraction and clean-up procedure for the determination of 15 organohalogenated pollutants (including brominated flame retardants) in aquaculture samples, using aluminium oxide basic and acidic silica gel in the supercritical extraction cell followed by gas chromatography with electron capture detection or mass spectrometry has been developed. This effective clean-up step ensures a minimum of chromatographic difficulties related to complex matrix components such as aquaculture feed. The extraction procedure has been screened by a fractional factorial design for the preliminary statistically significant parameters. The factors selected were extraction temperature, pressure, static extraction time, dynamic extraction time and carbon dioxide flow rate. The Doehlert design, followed by a multicriteria decision-making strategy, was then performed in order to determine the optimum conditions for the two most significant factors: pressure (165 bar) and dynamic extraction time (27 min). Under optimal conditions, the procedure developed with GC-MS/MS provides an excellent linearity, detection (0.01-0.2 ng g(-1)) and quantification limits (0.05-0.8 ng g(-1)) for most of the analytes investigated. The feasibility of the proposed supercritical fluid extraction method was validated by analysing two reference materials and fish feed and shellfish samples with satisfactory results.     

A micromodel analysis of factors influencing NAPL removal by surfactant foam flooding

A methodology to study the trichloroethylene (TCE) and dodecane removal in porous media by surfactant foams (SF) was presented by using etched-glass micromodels. The purpose of this work was to systematically evaluate the impact of various physicochemical factors such as gas fraction (GF), surfactant concentration, pore structure and nonaqueous phase liquid (NAPL) types on NAPL removal during SF flooding. The TCE displacement by SF was dependent on the gas fraction of SF. Low GFs (50% and 66%) were more efficient for TCE removal and sweep efficiencies than a high GF (85%). An increase in TCE removal was observed with increasing surfactant concentration at a fixed GF. TCE removal by SF flooding appeared to be dependent more to the value of Capillary number rather than to the concentration of surfactant solution. The effect of the pore heterogeneity was evaluated by employing two different types of micromodels. The Capillary number is an important parameter in the determination of sweep efficiency or gas saturation of SF in a nonhomogeneous porous medium. However, the TCE removal from a nonhomogeneous porous medium may not be associated with sweep efficiency. The initial configuration of residual TCE blobs in a nonhomogeneous porous medium would also be influential in displacing TCE. Sweep efficiencies and pressure responses of two NAPL systems (TCE and dodecane) were monitored to evaluate foam stability when the foam contacts the NAPLs. Stable foam contacting with TCE is implied, while it appears that dodecane cause the SF to collapse. All results indicate that the Capillary number (a ratio of viscous forces to capillary forces) is the most important parameter for TCE removal by SF flooding. Micromodel visualizations of water, surfactant and SF floods were showed and also discussed.     

Methode zum nachweis von rückständen der insektizide acephat, dimethoat, methamidophos und omethoat in kleinen nektarmengen

A gas chromatographic method for the determination of the insecticides acephate, dimethoate, methamidophos and omethoate in small amounts of nectar has been developed. By the use of a miniaturized extraction technique and a nitrogenphosphorus selective detector (NPD) residues down to 0.005 – 0.01 ppm could be detected in a sample size of 1 g. Because of the low content of co-extractives in nectar and the use of a highly selective detector a clean-up of the extracts was not necessary.     

Green Biomass Materials in Polyurethane Foams

Flexible polyurethane foams were prepared using naturally derived materials as alternatives to conventional auxiliary blowing agents. This research was based on the concept held by some that natural chemicals are better as a part of industrial ecology. The authors have attempted to define the foam manufacturing suitability of natural chemicals, but have not defined or defended the policy implications of such choices. Natural chemicals are often less suitable than those refined from petroleum and may then need some environmental credit related to greater discharge to be viable substitutes. Modest decreases in density (relative to foams without any auxiliary blowing agent) were obtained with the addition of solid CO₂ but other physical properties were not measured. It is unclear whether the reduction in density is a result of the phase change of CO, from solid to liquid within the polyurethane cell matrix or simply a bubbling effect of C02 in solution causing voids within the final product. Although it was anticipated that the high boiling point of limonene, from citrus peeis, would negate effectiveness as an auxiliary blowing agent, there were analogous decreases in foam density. The observed effect might be rationalized by the significant vapor pressure of limonene at temperatures lower than the boiling point. The limonene may be sweptf rom the foam system coincident with the loss of in situ generated CO₂ isoprene, naturally emitted from deciduous vegetation as well as from the combustion of carbonaceous fuels, provides a useful, if not complete, range of foam densities and may then be a partial substitute for halogenated auxiliary blowing agents. Switching from methyiene chloride to isoprene as the auxiliary blowing agent of choice would immediately decrease organic emissions from polyurethane foam plants by 20 percent (molecular weight effect). Regulation as a VOC and the residual acrid odor may be potential drawbacks to commercial utilization of isoprene.     

Population Exposure to Toxic Substances: Use of 1970 Census Data

A particulate sampling train has been constructed which satisfies the conflicting requirements of isokinetic sample extraction and constant flow rate through an inertial sizing device. Its design allows a variable fraction of the filtered emission gas to be added to the sample upstream of the inertial sizing device in order to maintain a preselected flow rate through this device while the gas flow rate into the sampling nozzle is adjusted to remain isokinetic with the local duct velocity. The prototype emission gas recycle (EGR) train was constructed by relatively simple modifications of a commercially available Method 5 sampling system, and much of the sampling technique is identical with Method 5 protocol. The train was tested by comparison of parallel runs in the EPA/SRI wind tunnel using redispersed fly ash. In one series of runs performed without inertial sizing devices, the EGR train and a colocated non- EGR train sampled 3-point traverses. The differences of the average mass concentrations measured by the two trains was 3.3 percent, with a standard deviation of 4.7 percent. In the next series of runs, identical cyclone inertial sizing devices were added to each train. The difference of the average mass concentration for these runs was 1.2 percent, with a standard deviation of 5.7 percent.     

Chemical composition and surfactant characteristics of marine foams investigated by means of UV-vis,FTIR and FTNIR spectroscopy

In this study, we collected the ultraviolet–visible (UV-vis), Fourier transform infrared (FTIR) and Fourier transform near-infrared (FTNIR) spectra of marine foams from different sites and foams produced by marine living organisms (i.e. algae and molluscs) to retrieve information about their molecular and structural composition. UV-vis spectra gave information concerning the lipid and pigment contents of foams. FTIR spectroscopy gave a more detailed qualitative information regarding carbohydrates, lipids and proteins in addition with information about the mineral contents of foams. FTNIR spectra confirmed the presence of carbohydrates, lipids and proteins in foams. Then, due to the higher content of structural information of FTIR spectroscopy with respect to FTNIR and UV-vis, we join the FTIR spectra of marine foams to those of humic substance from marine sediments and to the spectra of foams obtained by living organisms. We submitted this resulting FTIR spectral dataset to statistical multivariate methods to investigate specific aspects of foams such as structural similarity among foams and in addition, contributions from the organic matter of living organisms. Cluster analysis (CA) evidenced several cases (i.e. clusters) of marine foams having high structural similarity with foams from vegetal and animal samples and with humic substance extracted from sediments. These results suggested that all the living organisms of the marine environment can give contributions to the chemical composition of foams. Moreover, as CA also evidenced cases of structural differences within foam samples, we applied two-dimensional correlation analysis (2DCORR) to the FTIR spectra of marine foams to investigate the molecular characteristics which caused these structural differences. Asynchronous spectra of two-dimensional correlation analysis showed that the structural heterogeneity among foam samples depended reasonably on the presence and on the qualitative difference of electrostatic (hydrogen bonds) and nonpolar (van der Waals and π–π) interactions involving carbohydrate proteins and lipids present. The presence and relevance of these interactions agree with the supramolecular and surfactant characteristics of marine organic matter described in the scientific literature.     

Historic emissions of fluorotrichloromethane (CFC-11) based on a market survey

Releases of CFCs occur promptly from applications such as aerosol sprays, or over a period of several years from refrigeration and air conditioning or more slowly still from use as blowing agents for closed cell plastic foams. As a consequence of the Montreal Protocol, the emissions have fallen and their pattern is continuing to change. To help quantify these changes the emissions from closed cell foam blowing have been re-examined in a comprehensive market survey, developing a lifecycle assessment for each foam type, production method and foaming agent.The original model for the time series of emissions from foam applications was shown to remain a robust representation in general terms. There is an “immediate” loss when the foam is manufactured, a slow emission from the foam itself during use and a loss on disposal of the artefact made with the foam. The original model used an initial loss rate of 10% and a subsequent loss of 4.5% yr⁻¹ over 20 yr.The new survey showed a wide range of initial and service loss rates. Immediate release ranges from 95% down to 4%; similarly, the rate of loss during service varies from 0.5% to 5% yr⁻¹ and the service lifetimes of the artefacts made with the foams varies from 12 to 50 yr. The apparent emission function, in terms of the mean value of the annual fractional release from the bank of CFC-11 residing in foams, was calculated from the survey to be 0.043±0.008 over 28 yr. There is a small and non-significant fall in this function with time; so that over the last ten years of the data record the more appropriate value is 0.0366±0.0008. However, up to the early 1990s, it is the original emission function that is consistent with the observed atmospheric concentrations. Thenceforth this function seriously overpredicts the concentrations but, if the new emissions function for foams is used from 1993 onwards in conjunction with the original emission functions for all other uses, the fit becomes better. This suggests that the emission functions for prompt and short term releases remain valid and should be coupled with the new function to calculate emissions of CFC-11 or other fluorocarbon foam blowing agents from the early 1990s onwards.     

Inventory and substance flow analysis of polybrominated diphenyl ethers in the Nigerian transport sector—end-of-life vehicles policy and management

Recently, certain polybrominated diphenyl ethers (PBDEs) have been listed as persistent organic pollutants (POPs) in the Stockholm Convention. In this study, a preliminary material and substance flow analysis of commercial pentabromodiphenyl ether (c-PentaBDE) was conducted for motor vehicles—a major use sector for POP-PBDE in polyurethane (PUR) foam—for Nigeria. The methodology of the Stockholm Convention PBDE inventory guidance was used for the calculation of c-PentaBDE. Material/substance flow analysis was conducted applying the STAN software. The time frame for this analysis was 1980–2010, considering that this was the period when POP-PBDE-containing vehicles were largely imported into Nigeria.It is estimated that the approximately 19 million passenger cars imported from 1980 to 2010 contained ca. 270 t of POP-PBDEs in ca. 401,000 t of PUR foam. A major share of cars from the USA and only a small share of cars from Europe and Asia were impacted. This simplified material and substance flow of PUR foams and POP-PBDEs in motor vehicles demonstrated the potential for environmental/human contamination and pollution of recycling/reuse for Nigeria and other developing countries.The study developed the first preliminary inventory of end-of-life vehicles for Nigeria, following which the environment ministry has taken up the important issue of end-of-life vehicles management. Considering that a range of other pollutants are contained in vehicles (e.g. heavy metals, flame retardants, PCBs, chlorofluorocarbons, hydrofluorocarbons and waste oil), this initiated activity should finally lead to an integrated management of pollutants and resources from the transport sector.     

Validation of a multiclass multiresidue method and monitoring results for 210 pesticides in fruits and vegetables by gas chromatography-triple quadrupole mass spectrometry

A rapid, sensitive, accurate and reliable multiresidue method for the identification and quantification of 210 relevant pesticides in four representative fruit and vegetable commodities (tomato, potato, spring onion and orange) has been developed and validated by gas chromatography in tandem with triple quadrupole mass spectrometry. The method has been fully validated and applied to 292 samples from different countries. Prior to instrumental analysis, an extraction procedure based on a sample extraction of multiclass analytes, using the ethyl acetate method was employed. Mass spectrometric conditions were individually optimized for each compound in the selected reaction monitoring (SRM) mode to achieve maximum sensitivity. The pesticides were separated in less than 25 min. This was followed by an exhaustive control of the retention times. The Retention Time Locking Method was applied, working at a constant pressure throughout the analysis. System maintenance was reduced by using a purged capillary flow device that provided backflush capabilities by reversing column flow immediately after elution of the last compound of interest. Istotopically labelled internal standards were employed to improve the quality of the analytical results.     

Rapid multiresidue determination for currently used pesticides in agricultural drainage waters and soils using gas chromatography–mass spectrometry

An efficient and sensitive method for simultaneous determination of 38 pesticides in agricultural drainage waters and soils has been developed and validated. Water samples were extracted using solid-phase extraction with C18 cartridges while solid samples (suspended particle matter and soil) were extracted by using the quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction method. The target pesticides were analyzed by using gas chromatography-mass spectrometry with electron impact ionization. The proposed method allowed a simultaneous determination and confirmation of a large number of pesticides in agricultural drainage waters, suspended particle matters and soils/sediments with a good reproducibility and low detection limits. The developed method was applied to a survey of pesticides in a vegetable growing area of Guangzhou, China. The pesticides commonly found in the area were butachlor, carbofuran, dichlorvos, fipronil, isocarbophos and pyridaben.     

改性酚醛基炭泡沫的表面结构及脱硫脱硝

采用前驱体改性的方法,以CuCl2、FeCl2和MgCl2为改性剂,制备出改性酚醛泡沫,经炭化/活化得到改性酚醛基炭泡沫。研究了不同金属对酚醛基炭泡沫表面物理与化学特性的影响,并进行同时脱硫脱硝实验研究。通过研究发现,添加CuCl2的样品比添加FeCl2、MgCl2的样品的中孔孔容大接近10倍;比表面积和孔容是CFCu>CF0>CFFe>CFMg;金属改性剂主要以金属和金属氧化物的形式存在于酚醛基炭泡沫中,而表面其他官能团大体结构不变。经CuCl2、FeCl2和MgCl2改性后,脱硫效率分别提高了39%、11%和13%,脱硝效率分别提高了19%、10%和4%,其中以CuCl2改性的酚醛基炭泡沫的效率最高。     

Multiresidue analysis of organophosphate and pyrethroid pesticides in duplicate-diet solid food by pressurized liquid extraction

An analytical method was developed for determining organophosphate pesticides (OPP) and pyrethroid pesticides (PYR) in duplicate-diet solid food. The method consisted of pressurized liquid extraction (PLE) with dichloromethane followed by cleanup with gel permeation and solid phase extraction columns and gas chromatography/mass spectrometry (GC/MS) analysis. Quantitative recoveries (73-117 %) of the target pesticides were obtained for spiked duplicate-diet food samples. The percent standard deviation (% RSD) of replicate food samples was within ± 20 %. Another method was developed for determining a common OPP metabolite, 3, 5, 6-trichloro-2-pyridinol (TCP) in duplicate-diet food. The method consisted of a PLE with methanol followed by liquid-liquid partitioning, derivatization, and GC/MS analysis. Recoveries of TCP ranged from 83 to 101 % for spiked duplicate-diet food samples. The % RSD of replicate food samples was within ± 15 %. The results confirmed that these methods are reliable and robust, and that they can be used in routine analysis. In addition, a storage stability study for a common OPP, chlorpyrifos (CPF), in solid food samples was performed. The fortified (15)N-(13)C-labeled CPF was stable over 16 mo storage at -20° C in the dark. The developed analytical methods were successfully applied to 278 duplicate-diet food samples from preschool children, demonstrating that these methods are robust and suitable for routine analysis in future exposure monitoring studies.     

Multiresidue analysis of organophosphate and pyrethroid pesticides in duplicate-diet solid food by pressurized liquid extraction

An analytical method was developed for determining organophosphate pesticides (OPP) and pyrethroid pesticides (PYR) in duplicate-diet solid food. The method consisted of pressurized liquid extraction (PLE) with dichloromethane followed by cleanup with gel permeation and solid phase extraction columns and gas chromatography/mass spectrometry (GC/MS) analysis. Quantitative recoveries (73–117 %) of the target pesticides were obtained for spiked duplicate-diet food samples. The percent standard deviation (% RSD) of replicate food samples was within ± 20 %. Another method was developed for determining a common OPP metabolite, 3, 5, 6-trichloro-2-pyridinol (TCP) in duplicate-diet food. The method consisted of a PLE with methanol followed by liquid-liquid partitioning, derivatization, and GC/MS analysis. Recoveries of TCP ranged from 83 to 101 % for spiked duplicate-diet food samples. The % RSD of replicate food samples was within ± 15 %. The results confirmed that these methods are reliable and robust, and that they can be used in routine analysis. In addition, a storage stability study for a common OPP, chlorpyrifos (CPF), in solid food samples was performed. The fortified ¹⁵N-¹³C-labeled CPF was stable over 16 mo storage at ?20° C in the dark. The developed analytical methods were successfully applied to 278 duplicate-diet food samples from preschool children, demonstrating that these methods are robust and suitable for routine analysis in future exposure monitoring studies.     

A method to determine residue levels of persistent organochlorine pesticides in human milk from Indonesian women

A method has been developed for the analysis of organochlorine pesticides in human milk using solvent extraction, Florisil solid phase extraction clean-up and analysis by gas chromatography with an electron capture detector. The recovery of analytes from spiked milk samples was in the range 53 +/- 1% to 109 +/- 7% (n = 9). A small number of samples were obtained from women in a rural and an urban area of Indonesia and analysed using the developed method. The results are reported on a milk fat basis. All samples contained detectable residues of p,p'-DDT (urban mean 0.11 +/- 0.18 mgkg(-1) (n = 5), rural mean 0.07 +/- 0.03 mg kg(-1) (n = 5)) and p,p'-DDE (urban mean 0.05 +/- 0.04 m kg(-1) (n = 5), rural mean 0.76 +/- 1.46 mg kg(-1) (n = 5)). Residues of HCB, betaHCH, alpha-endosulfan and dieldrin were also detected in some samples. There was no significant difference (at the 95% confidence level) in levels of pesticides between urban and rural areas. The levels of organochlorine pesticides in milk from Indonesian women were lower than those reported from Indonesian women exposed to DDT through malaria eradication schemes and were similar to levels reported from UK and Japan.