Warren Spring Laboratory Research Articles

Synthesis and Evaluation of New Anionic Gemini Dispersants as Oil Dispersants to Treat Crude Oil Spill Pollution

AbstractFloating petroleum oil spills on the marine ecosystem are generally associated with an escalation of serious environmental problems. This research aimed to synthesis five water‐soluble anionic Gemini dispersants to minimize the effect of floating petroleum oil spills on the marine ecosystem. Referring to the spacer type, these dispersant are classified into two categories: the first category is the three acyl amine Gemini dispersants of N,N′‐ diacyl, (distearoyl‐, dipalmitoy‐, and dimyristoyl‐) N,N‐′ sodium 2‐hydroxy 3‐propane sulfonate propane 1,3 diamine, denoted S, P, and M, and the second category is two alkyl amine Gemini dispersants of N,N′dialkyl ‐(dicetyl‐, and dilauryl‐) N,N′‐sodium 2‐hydroxy 3‐propane sulfonate propane 1,3 diamine, denoted C and L. Fourier transform infrared and 1H NMR spectroscopy, gel permeation chromatography, and elemental analysis were used to verify the chemical formula of the synthesized dispersants. The effectiveness of the synthesized dispersants was investigated as regards their dynamic interfacial tension, carbon–chain length, and hydrophilic–lipophilic balance. The dispersion efficiency of the synthesized dispersant was detected qualitatively and quantitatively using the screen test and Warren Spring Laboratory methods, respectively. Experimental outcomes showed that the maximum dispersion efficiency of 94.7 wt% was achieved by dispersant C at a dispersant\oil ratio of 1:20 at 25°C.

Special Issue to mark the career and the retirement of Professor Michael Cox as the Chemical Technology Editor of the Journal of Chemical Technology and Biotechnology

Special Issue to mark the career and the retirement of Professor Michael Cox as the Chemical Technology Editor of the Journal of Chemical Technology and Biotechnology

Studies in support of the regulation of dispersant use in the Kazakhstan Sector of the Caspian Sea (KSCS)

ABSTRACT The use of oil spill dispersants is often regulated by national authorities to ensure that products approved for use as dispersants on spilled oil in national waters are of reasonable effectiveness and of low inherent toxicity. KING (Kazakh Institute of Oil & Gas) undertook a study to assess the use of oil spill dispersants on spilled oils in the Kazakhstan sector of the Caspian Sea (KSCS) to support decision-making for such regulations in the RoK (Republic of Kazakhstan). The KSCS has some characteristics that are unlike open ocean conditions in other parts of the world; the salinity is much lower than in the open sea. The shallow waters of the northern Caspian Sea have very low salinity (9 psu (practical salinity units) or less) due to the inflow of freshwater from the River Volga, and are frozen in winter. The deeper water in the southern part of the KSCS has a salinity of up to 14 psu. The effectiveness of oil spill dispersants is known to be affected by water salinity. Different countries around the world have developed different test methods to assess dispersant effectiveness. The project examined the options and decided to modify the WSL (Warren Spring Laboratory) LR 448 dispersant effectiveness test method, as used in the UK. The method was adapted by KING and testing was conducted by Karaganda State University (KSU) to test a variety of dispersants under Caspian Sea conditions. Dispersant effectiveness testing should be conducted with a test oil that is representative of oils that might be spilled in the area being considered. Kashagan crude oil was distilled to 200°C to simulate the evaporative loss that would occur shortly after the oil was spilled at sea and the residue used as the test oil in the dispersant effectiveness testing. Several commercially-available dispersants were tested using the modified LR 448 method with the 200°C+ Kashagan test oil under a variety of conditions with salinities ranging from 0 psu to 35 psu and at temperatures of 5°C and 25°C. The results indicate that some internationally recognized dispersants could be suitable for use in the KSCS.

Study of the rheological behaviour of monomodal quartz particle beds under stress. A model for the shear yield functions of powders

A model is proposed that describes the yield locus of powders. The model is based on the adhesive contact of elastic spheres theory developed by Johnson, Kendall, and Roberts (JKR model). The proposed model improves the results by applying the Warren Spring Laboratory (WSL) equation and the Coulomb model. Only two parameters are needed in the present model to describe the yield locus of a powder: powder cohesion ( C) and the coefficient of friction ( μ) of the powder bed. The study verifies the validity of the new equation to describe the yield locus of different powders. The proposed model was used to calculate the cohesion and coefficient of friction of monomodal quartz particle beds with different average particle sizes. The study examines the influence of average particle size ( d s ) and bed compactness ( ϕ) on these parameters. Cohesion was observed to increase by the sixth power of compactness and inverse of the particle Sauter diameter. The bed coefficient of friction increased asymptotically with bed compactness, this relationship depending on particle size.

Assessment of the dustiness and the dust liberation mechanisms of limestone quarry operations

In surface mineral workings, dust is potentially generated from a range of activities like site preparation, stockpiling, loading, transportation and mineral processing operations. Aggregate quarries are one of the largest extractive industrial sectors in UK. This project investigates the propensity of a limestone ore to generate dust due to handling and comminution processes. The dustiness of a limestone ore is assessed using the Warren Spring Laboratory rotating drum (HSE-WSL). The effect of the operating parameters of the WSL rotating drum to the dustiness of limestone is evaluated prior to testing. Preliminary testing on the effect of the operational parameters to the dustiness values showed that the consistency of the end results is closely related to them, thus they need to be carefully controlled. Also, control testing took place to identify the maximum dustiness value per operational parameter, so as to define an optimum set for the limestone sample. This testing procedure is compared with the HSL proposed testing procedure and their differences are quantified. The use of the optimum experimental protocol (OPT-TP) determined by preliminary testing yielded much higher dustiness values even though the initial mass of test material is less than the sample mass used in the HSL testing procedure (HSL-TP). A variety of different fractions is tested and the dustiness indices of the total dust and the health related fractions are determined. Different limestone fractions were found to exhibit different dustiness levels, whereas the concentration of fine material in the test sample is closely related to the dust yield. The airborne fraction was collected for particle size analysis. The dust particle size distributions and the cumulative percentages of volume concentrations below 10 and 2.5 μm were determined. Experimental conclusions proved that control over operational parameters of industrial processes (i.e. conveying of materials, stockpiling) such as the time scale of a process or the limestone mass could contribute to potentially lower levels of particulate matter. Also, lower concentrations of fine material within industrial processes could conclude to lower dust yield. The minimization of fine material could be achieved through optimization practices of the degradation—classification processes (comminution, sieving, etc.). Dustiness measurements and particle size analysis are valuable tools to the mining sector, legislative parties and occupational hygienists as they can assist the development of a correct dust assessment plan as well as mitigation methodologies, work practices and health and safety regulations.

ASSESSING DISPERSANT EFFECTIVENESS FOR HEAVY FUEL OILS USING SMALL-SCALE LABORATORY TESTS

ABSTRACT Four bench-scale dispersant tests were used to evaluate three dispersants, Corexit 9500, Superdispersant 25 and Agma Super-concentrate DR 379 with an IFO (Intermediate Fuel Oil) 180 and an IFO 380. Dispersant effectiveness was assessed using the Swirling Flask Test (SFT) and Baffled Flask Test (BFT) developed by the U.S, Environmental Protection Agency (EPA), the Exxon Dispersant Effectiveness Test (EXDET) developed by ExxonMobil, and the Warren Spring Laboratory (WSL) test utilized in the United Kingdom. This study allows comparisons among the small-scale laboratory tests and provides a basis to compare dispersant effectiveness data with findings from at-sea field trials and wave basin studies conducted with the same dispersants and oils. No single dispersant preformed with the highest effectiveness under all test methods, but the data demonstrate that viscous oils such as IFO 380s could be dispersed under the right conditions. The results show that laboratory tests with greater mixing energy yield the highest estimates of dispersant effectiveness.

Dispersant Effectiveness on Heavy Fuel Oil and Crude Oil in New Zealand

ABSTRACT The New Zealand (NZ) Maritime Safety Authority (MSA) recently identified seven crude oils and nine IFO-380 heavy fuel oils used or transported in NZ waters that had a high relative risk of being spilt. To determine the relative effectiveness of dispersants stocked by the MSA (Corexit 9527, Slickgone LTSW, Gamlen OSD LT, and Tergo R40) on the oils, effectiveness was tested using the Warren Spring Laboratory (WSL) LR 448 protocol. All testing was on fresh (unweathered) oil at 15°C, at a dispersant to oil ratio (DOR) of 1:25. Effective dispersion was considered to be equivalent to a WSL test result of ≥15%, as proposed in the work of Lunel & Davies (1996). Overall, the seven crude oils tested could be dispersed with MSA stocked dispersants; Corexit 9527 and Slickgone LTSW dispersing the greatest volume of oil, while Gamlen OSD LT and Tergo R40 were effective on the widest range of oils. For the nine IFO-380 heavy fuel oils, dispersant effectiveness was generally lower than for crude oils, and two oils could not be dispersed. Corexit 9527 was the most effective dispersant and worked on the widest range of fuel oils. Slickgone LTSW, Gamlen OSD LT, and Tergo R40 were less effective and worked on a smaller range of fuel oils. To assess whether other dispersants not currently stocked by the MSA offered a significantly improved capacity, two high performance products (Corexit 9500 and Slickgone EW) were tested on the same oils, and across a range of temperatures and DORs. Laboratory results showed that Corexit 9500 and Slickgone EW were significantly more effective on both the crude oils and the IFO-380 heavy fuel oils than existing MSA dispersant stocks. While the results of this study provide a good indication of the relative effectiveness of different dispersants, they do not indicate absolute levels of effectiveness, and field experiments are needed to define how laboratory effectiveness translates to effectiveness in the field.

Atmospheric accessions of heavy metals to some New Zealand pastoral soils

Total heavy metal deposition was monitored at seven rural sites across New Zealand to determine the rate of atmospheric deposition of heavy metals to soils and to evaluate any regional and temporal variations in metal deposition. Heavy metal deposition was collected monthly in Warren Spring Laboratory type inverted frisbees. The rate of heavy metal deposition followed the order Zn≫Cu>Cr>Pb>Ni≫Cd. There were no obvious trends with regards to either seasonal or spatial deposition for any of the heavy metals measured. With the exception of Zn, heavy metal deposition in New Zealand was generally lower than rates measured in other countries. This reflects the general lack of high temperature industrial processes from urban-based industrial processes that are an important source of heavy metal aerosols in other industrialised regions worldwide. The inverted frisbee technique used provides a reliable indication of the magnitude of deposition of heavy metals from the atmosphere at a reasonable cost and with manageable logistical effort for a national survey.

Suggested guidelines for deposited ambient dust

Despite deposited dust being one of the main causes of complaint about air pollution, no international or national (U.K.) standards or guidelines currently exist. Various difficulties in defining nuisance levels for deposited dust have militated against the use of guidelines on anything other than an ad hoc, site-specific basis. However, a need clearly exists for guidelines of wider relevance. A novel method of producing guidelines is proposed for monthly dustfall results based on the background levels normally expected. By adopting the concept of “likelihood of complaint”, already used successfully for rating the impact of noise, the various difficulties inherent in defining dust nuisance standards per se are avoided. Monthly data for British Standard deposit gauges from the Warren Spring Laboratory (U.K.) National Survey of Air Pollution (grit and dust) have been re-analysed by the authors for gauges “sited to catch general deposit”. Where local background data are limited or absent, it is suggested that summary statistics from this analysis of national background data could provide an appropriate basis for the proposed guidelines. Although this method is primarily applicable to British Standard and Frisbee-type deposit gauges, it could be adapted for use with other devices used for monitoring deposited dust.

The expected mass fraction

A new measure is introduced to characterize the reduction of concentration values found in a contaminant cloud. The “expected mass fraction” presents the mass of contaminant (or exposure time) at the various contaminant concentration values observed when a contaminant cloud passes over a fixed sampling location. This measure is shown to be easy to compile and to provide a reasonable ensemble average approximation with as few cloud releases as would be required for the more conventional dosage measurement. The new measure is shown to have a good prospect of theoretical predictability due to its definition in terms of the one-point probability density function of contaminant concentration and recent advances in predicting the moments of that probability density function. Experiments from the Warren Spring Laboratory are used to illustrate the application of the “expected mass fraction”.

Comment on predictive equation published by Spanton (1983)

A method for estimating long-period pollution means, based on the Gaussian model of pollutant dispersion, has been widely applied by Warren Spring Laboratory to urban emissions of smoke and sulphur dioxide. However,.the report which is cited as the source of full model details (Spanton, 1983) contains an incorrect formulation of one of the equations, use of which results in a marked discontinuity in the profile of concentration against distance. This error is of most relevance when the model is applied to point source emissions under atmospheric conditions of high stability or high instability, although in the context of long-period mean urban pollution the error is of minor importance.

WEATHERING AND CHEMICAL DISPERSION OF OIL AT SEA

ABSTRACT Small-scale laboratory methods were used to simulate the weathering processes that occur when crude oil is spilled at sea. Changes caused by evaporation and water-in-oil (w/o) emulsification were studied separately. W/o emulsions were assessed for chemical dispersibility using the Institut Français du Petrole (IFP) and Mackay-Nadeau-Steel-man (MNS) methods. Larger scale experiments were performed in a meso-scale flume. Crude oil was weathered for three days and then sprayed with dispersant. The results show that emulsion breaking is an important part of the mechanism of chemical dispersion. IFP, MNS, and Warren Spring Laboratory (WSL) tests, conducted on w/o emulsions recovered from the flume, produced much lower levels of dispersion than did treatment in the flume. The standard test procedures do not permit emulsion breaking to proceed to the extent observed in the flume. A sea trial also was conducted. Preliminary evaluation of the results shows that dispersant application partially broke the w/o emulsion that had rapidly formed. Dispersion proceeded at a slow rate but the treated slick was removed from the surface more rapidly than the control slick. The degree of dispersion was difficult to quantify by visual observation due to the weather conditions. A combination of remote sensing, surface sampling, and subsurface fluorometry provided a more reliable estimate.

Stickiness – A Comparison of Test Methods and Characterisation Parameters

ABSTRACT The stickiness of adipic acid and alumina was tested in equipment for powder characterisation. Experiments covered various moisture contents at ambient temperature. Both wall adhesion and internal cohesion tests were carried out. The testers evaluated were the Jenike and Peschl shear cells, the Warren Spring Laboratory Cohesion tester, the unconfined yield strength tester, and the Teesside Laminated shear cell. In addition, the empirical tests put forward by Can (1) were carried out. The sticky-point temperatures of various amorphous materials were also tested. The Jenike shear cell and the Warren Spring Cohesion tesm gave the most consistent and repeatable results for cohesion. None of the equipment tested gave a simple and repeatable measure of adhesion. The tester developed by Howe et al (2) determined the sticky-point quickly and repeatably. Fluidisation tests were carried out in a small scale visualisation module. The results correlated well with the measured cohesion parameters.

The Porto Torres biodepyritization pilot plant: Light and shade of one year operation

The nominal 50 kg h −1 dry coal biodepyritization pilot plant was built at Porto Torres (Sassari, Italy) in the area of EniChem S.p.A. Chemical Works, with financial support of the Commission of European Communities and with the participation of the DMT of Essen (Germany), the Mining and Mineral Processing Department of the University of Cagliari (Italy), the Technical University of Delft (The Netherlands) and the Warren Spring Laboratory of Stevenage (UK). The plant went on stream in early September 1992. Test runs were carried in the range 6.5–41.5% solids concentration. For every solids concentration the steady state was attained in about 10 d. For all the test runs the assays showed that more than 90% pyrite removal is achieved in the first five bioreactors; for a pulp flow rate of 6.94 × 10 −2 dm 3 s −1, (250 l h −1) and useful bioreactor volume of 7.5 m 3, this corresponds to a residence time of 540 345 s, i.e., 6.254 d, and to a pyritic iron biosolubilization rate of 36 mg dm −3 h −1. The pyrite biosolubilization rate constant is 1.53 × 10 −2 h −1. The power input per bioreactor operating on a 40% solids pulp is 4 kW with cos Φ = 0.76. Hence, the power required for processing 100 kg h −1 coal at 40% solids in the bioreactor section is 4 × 5 = 20 kW h, i.e. 200 kW h per tonne dry coal.

5TH Eurasap international workshop on wind and water tunnel modelling of atmospheric flow and dispersion, 30 October–1 November, 1991, Warren Spring Laboratory, Stevenage, Herts, U.K.

5TH Eurasap international workshop on wind and water tunnel modelling of atmospheric flow and dispersion, 30 October–1 November, 1991, Warren Spring Laboratory, Stevenage, Herts, U.K.

Assessing recent surface ozone concentrations in the U.K.

A 17-site national ozone monitoring network was established in 1987 by Warren Spring Laboratory and other organizations for the U.K. Department of the Environment. 1989 was the most photochemically active year since the network commenced full operation. This paper therefore provides the first comprehensive analysis of U.K. ozone levels during such a period of interest. Although significantly greater numbers of photochemical episodes were observed in 1989 than in the previous 2 years, trend analysis of measurements from long-running sites over the last 15 years demonstrates that this year was not exceptional when viewed in a long-term context. Network data are here compared with the World Health Organization guidelines for ozone. All criteria examined are widely exceeded throughout the U.K., and in particular during photochemically active years such as 1989. Detailed spatial patterns of ozone concentrations throughout the U.K. are described for the first time: those for short term (hourly and 8-hourly) concentrations show a clear north/south gradient every year since 1987. The patterns observed are consistent with broader features of ozone variation throughout continental Europe. Substantially different spatial patterns are observed when daily average concentrations are examined, with concentrations being highest in rural areas with low NO x emissions.

A field comparison of dust deposit gauge performance at two sites in Yorkshire, 1987–1989

General dissatisfaction with the efficiency of the standard dust deposits gauges currently in use has led recently to the development of alternative designs. One such gauge based on an inverted Frisbee, and developed by Warren Spring Laboratory, Stevenage, showed promise in wind tunnel studies. This paper describes field trials of two types of inverted Frisbee gauge (the wet Frisbee and the dry Frisbee) which were operated alongside the British Standard and the proposed ISO standard dust deposit gauges. Continuous monitoring was carried out at two sites in North Yorkshire for 2 years. Undissolved particulate matter from each gauge was weighed and a sub-sample characterized by microscopic examination of individual particles ⩾50 μm in diameter, in order to identify possible sources of the dust. Wet Frisbee gauges collected and/or retained significantly more dust than either the British Standard gauges or the ISO gauges. The dry Frisbee gauge also proved to be efficient and, having practical advantages over the wet Frisbee, is recommended as a possible alternative to both the British Standard and the proposed ISO standard dust deposit gauges.

Book Reviews: PROCEEDINGS OF A CONTAMINATED LAND WORKSHOP HELD AT THE WARREN SPRING LABORATORY U.K. IN SEPTEMBER 1990. Published by Warren Spring Laboratory, Stevenage, Herts SG1 2BK, U.K. Reviewed by Alan Parker, GIBB Environmental Sciences, Abingdon, U.K

Book Reviews: PROCEEDINGS OF A CONTAMINATED LAND WORKSHOP HELD AT THE WARREN SPRING LABORATORY U.K. IN SEPTEMBER 1990. Published by Warren Spring Laboratory, Stevenage, Herts SG1 2BK, U.K. Reviewed by Alan Parker, GIBB Environmental Sciences, Abingdon, U.K

Solvex: A database for the selection and appraisal of solvent extraction reagents

The design of a solvent extraction process can cause considerable problems regarding the choice of reagents. Reagent selection is based upon the evaluation of many criteria, for example the ability of a reagent to transfer a metal selectively across the aqueous/organic interface in both directions and the ability of the extractant/diluent mixture to perform efficiently in terms of reaction rates and stabilities. Other factors are also important such as reagent availability, cost, capacity and toxicity. Manufacturers, world wide, are continuously seeking new and improved reagents and so the already large range is steadily growing, adding to the dilemma. In response to these problems the Solvent Extraction Database, SOLVEX, was developed at Warren Spring Laboratory, in association with the Minerals Industry Research Organisation. It offers a single comprehensive source of reliable, quantitative information compiled into a single, standard format. A large part of the database consists of performance data which is essential to the process designer. The recent addition of a graphical interface has greatly enhanced the ability of the system to allow the efficiency of different systems to be compared and evaluated. SOLVEX also stores data concerned with the physical properties of the reagents and physicochemical data such as specific gravity, solubility, interfacial tension, viscosity and toxicity. There are also comprehensive sections on commercial information and references. This paper describes the database and the graphical interface and discusses the advantages it can offer process engineers and manufacturers alike.

The application of health-related size fractions to dustiness measurement

This report describes the progress towards a new standard dustiness test made at the Warren Spring Laboratory. The most important feature of the test is the use of polyurethane foam to separate the dust given off in the test into the health related size fractions defined recently by an ISO-CEN working group. The work shows that with adequate controls meaningful results can be obtained from the test.