Academic literature on the topic 'Dispersed oil'

In this work, the oil-dispersed polydimethylsiloxane (PDMS) sterically stabilised poly(Methl Methacrylate-2Vinyl Pyridine) p(MMA-2-VP) particles are investigated for use as Pickering emulsifiers with varied emulsification conditions (pH, particle concentrations and oil-water volume ratios) and their adsorption behaviours on 2-Dimensional curved oil-water interface. These particles are synthesised by dispersion polymerisation in dodecane and their particle content can be controlled by varying the initial MMA: 2-VP ratio (uncrosslinked particles with varied MMA-2-VP ratio in particle cores) and crosslinker concentrations (cross-linked particles with constant initial MMA-2-VP ratio). Transitional phase inversion from w/o to o/w emulsions which are stabilised by oil-dispersed p(MMA-2-VP)-PDMS particles is induced by tuning pH from 6 to 2 in aqueous phase, regardless of particle concentrations. It is the first time reported of such phase inversion in emulsions stabilised with responsive emulsifiers by responding to the relevant environmental trigger. This phenomenon occurs only in the emulsion systems that prepared in the presence of such oil-dispersed particles containing more than 62% p2-VP in cores. The particles which synthesised with 5 mol% (respect to monomer concentration) cross-linkers can stabilise most stable emulsions than others, in particular the o/w emulsion, no released oil can be observed after 10 months preparation. Pickering emulsions are also prepared by changing the oil-water volume ratio under different pHs. Catastrophic emulsion phase inversion from single emulsions to multiple emulsions are observed under certain experimental conditions, indicating that such phenomenon is not only controlled by increased dispersed phase fraction in emulsion systems but also governed by the proton concentration/quantity in aqueous phase. The o/w high internal phase emulsion gels are stabilised by such oil-dispersed pH responsive particles which synthesised with 5 mol% (respect to monomer concentration) cross-linkers at pH 2 with 70 vol% oil phase. Eventually, the measurement of interfacial tension as a function of time in the presence of varied concentrations of oil-dispersed pH responsive particles are performed basing on a pendant drop method. Oil-dispersed pH responsive particles are more interfacially active at uncharged state than charged state. The adsorption coefficient value is large at charged state (pH2) than uncharged state (pH 6), implying the fact that such particle stabilised emulsion properties are governed mainly by their adsorption kinetics.

This thesis reports on experimental and theoretical investigations relevant to the understanding of the phenomenon of phase inversion and its effect on pressure drop during dispersed flow of two immiscible liquids in horizontal pipelines. Experimental studies of phase inversion and associated phenomena were carried out in the liquid flow facility in the Department of Chemical Engineering at University College London (UCL), and at the Norwegian University of Science and Technology, Trondheim, Norway (NTNU). Detailed local conductivity measurements have been obtained at UCL (using conductivity ring probes, a local needle conductivity probe and a flush probe mounted on the pipe wall), which revealed phase continuity at different locations in the pipe cross section as the system approaches phase inversion and after it. In both systems, pressure gradient was measured and phase inversion identification measurements along the pipe were enabled with the use of the conductivity ring probes. A new probe that enables phase and drop size distribution measurements was designed and developed for use at UCL. At the UCL facility, velocity ratio of the two phases, the dispersed phase droplet velocity profiles, and phase distribution at the pipe cross section and droplet chord length were also measured. This revealed a significant increase in the dispersed drop size at inversion point. The results also enabled the equal surface energy criterion validation, based on droplet size considerations. The velocity ratio of the two phases was found to have a higher value than unity at all conditions studied, while inversion from water to oil continuous mixtures results in a decrease in its value. The drop velocity was also becoming lower with increasing dispersed phase fraction and it was found to be affected by the presence of high dispersed phase concentrations. Various parameters and their effect on inversion were studied. Three types of oil (with viscosities of 1.7, 5.5 and 11 mPa s) were used while different pipe diameters and materials were tested (namely, acrylic with 32 and 60 mm ID, stainless steel with 38 and 60 mm ID and an epoxy coated stainless steel pipe with 60 mm ID). Mixture velocities from 2.5 m/s to 6.2 m/s (depending on the test section) were used, selected so that the mixture away from the inversion was dispersed. Also, two experimental routes were followed, starting from oil continuous and water continuous dispersions to investigate the existence of a possible hysteresis at the occurrence of inversion. It was found that phase inversion is accompanied with significant changes in pressure gradient it was preceded by a sharp peak when the less viscous oils were used, while no peak was recorded with the use of the more viscous oil. An ambivalent range was seen for the less viscous oil, possibly related to the creation of secondary dispersions. A mechanistic model that describes the layered structure of the flow during inversion (detected experimentally) was proposed for the prediction of flow characteristics and pressure gradient at the region of inversion. It is suggested that inversion starts when a thin layer of the dispersed phase (that is to become continuous) forms at the top or the bottom of the pipe. A clear layer of the continuous phase may also exist at the bottom or the top of the pipe respectively. Two or three layer models were used for these configurations. Results showed that the two layer model predicts pressure gradient and layer thickness well. The homogeneous model was found to agree well with the experimental results, especially in the water continuous region when considerations for the mixture velocity. The friction factor was modified to compensate for the appearance of the drag reduction in the conducted measurements. In addition, a commercial feasibility study has been carried out which confirmed the considerable and immediate potential for the commercialisation of the impedance probe developed within this research for phase and drop size distribution measurements.

Oil spill is a major source of pollution in Kuwait marine environment and oil dispersants are used as a method to combat oil spill but the adverse effects of either oil or dispersed oil is unknown to fish species local to Kuwait. Therefore, the toxicity of water-accommodated fraction (WAF) of Kuwait crude oil (KCO) and chemically enhanced water-accommodated fraction (CE-WAF) of KCO with three dispersants (Corexit® 9500, Corexit® 9527 and Slickgone® NS) were investigated against selected marine fish species local to Kuwait marine waters such as: sobaity-sea bream (Sparidentex hasta), hamoor-orange-spotted grouper (Ephinephelus coicoides), meidmullet (Liza Klunzingeri), and shea’am-yellow-fin sea bream (Acanthopagrus latus). Prior to exposure chemical characterization of KCO WAF and CE-WAFs was conducted for benzene, toluene, ethylbenzene and xylene (BTEX), polycyclic aromatic hydrocarbons (PAH), aliphatic and total petroleum hydrocarbons (TPH) compounds. Standardization experiments regarding oil loading and mixing duration revealed that 1 g KCO loading and 24 h mixing duration were the most appropriate experimental conditions to obtain a reproducible and stable WAF and CE-WAF solutions. In general, CE-WAF contained higher concentrations of TPH, PAHs and aliphatics compared to KCO WAF. Exposure to KCO WAF and CE-WAF had no adverse effects on hatching success of embryonated eggs of sea bream and orange-spotted grouper exposed but larvae hatched during exposure exhibited a toxic response. Considering larval sensitivity, pre-hatched larvae of four marine fish species were separately exposed to KCO WAF and their sensitivities from the most sensitive to the least sensitive were: sea bream>orangespotted grouper > yellow-fin sea bream > mullet pre-hatched larval stages. The sensitivities of pre-hatched larvae of sea bream and orange-spotted grouper to WAF and CE-WAF were of different degrees. For sea bream the LC50 values were around 0.120 g oil/L for both WAF and CE-WAF indicating that dispersant didn’t increase oil toxicity, whereas for orange-spotted grouper CE-WAF (LC50 0.010 g oil/L) was more toxic than WAF alone (LC50 0.93 g/L). The data obtained in this study showed that most resistant developmental stage of fish to the toxicity of WAF and CE-WAFs was the egg stage > ABSTRACT ©KARAM v larvae hatched during exposure > pre-hatched larvae. Exposure of pre-hatched larvae to KCO WAF induced developmental abnormalities in spinal curvature of larvae and the most prominent deformity types were lordosis, scoliosis and kyphosis compared to that of control larvae were no abnormalities were observed. Relating toxicity data obtained in the present experimental study to actual petroleum hydrocarbon concentrations in Kuwait marine area, it was observed that current contamination level with petroleum hydrocarbons is far less than the LC50 determined in this study suggesting that there isn’t any acute hazard to either fish egg hatching or larva survival.

Petroleum refining is among the most important industries in the world. The oil refinery products contribute in many essential issues in the human life including transportation fuels, heating fuels, petrochemical industries, etc. Although oil refining is an old process started in the mid of the 19th century, new developments and technologies are introduced frequently due to the large amount of studies conducted around the world research centres. Some of the petroleum refining processes gain more attention in terms of research and development in the last couple of decades. For example, the importance of developing the hydrocracking process is increasing due to the increasing amount of heavy unconventional oil reserves. Another hot topic is the development of the hydrodesulphurization process due to the environmental concern about the sulphur oxides emissions produced by using oil refinery streams that contain several organic sulphur compounds. In this work, commercially available slurry catalyst precursors are tested to study the impact of the catalyst preparation conditions on its characteristic and activity. Those types of catalysts are used for hydrocracking and upgrading processes of heavy crude and residue including sulphur and other metal removal. The main subject was to approach the desulphurization activity and selectivity of the catalyst in removing dibenzothiophene (DBT) from model feed. DBT is one of the refractory sulphur compounds in the heavy oil fractions. It was found that changing the preparation conditions in terms of temperature, pressure and sulphiding agent influenced the activity and selectivity of the produced catalyst between the direct desulphurization reaction pathway and hydrogenation reaction pathway in removing DBT. The highest conversion was achieved by using cobalt-molybdenum-sulphide catalyst (Co-Mo-S) where up to 94.0 wt% of the DBT was converted. Adding the same catalyst precursor directly to Arab heavy crude oil, high desulphurization level was achieved where 70 wt% of the sulphur content of the feed has been removed. In addition, there is a high potential to increase this desulphurization level in treating heavy crude by applying the optimum operation conditions used in presulphiding the catalyst precursor. Ionic liquids (ILs) were also employed for sulphur removal from refinery streams by liquid-liquid extraction process. The ILs are organic salts with low melting points, mostly at room temperatures. Although the sulphur extraction level was very low comparing with the conventional hydrotreating process, this process has the advantage of minimizing the operation costs by reducing the reaction severity in terms of temperature and hydrogen consumption. Around 80 wt% of DBT was removed from model compound using one of the tested ILs. The nitrogen removal was also very high where almost 99 wt% of pyridine was removed from the model oil. However, the sulphur extraction level decreased in treating diesel fuel due to several factors such as the aromatic contents of the feed and the existence of several sulphur and metal compounds. To overcome this problem, the extraction process was repeated several times using fresh batches of ILs. This point has driven the importance of developing an efficient regeneration method for the used IL which was also approached in this work.

In 1984, experimental oil and dispersed oil spill sites were established along the Caribbean coast of Panama, in the Province of Bocas del Toro. Baseline biological, chemical, and physical parameters were collected prior to dosing. Over the following 2.6 years, sites were monitored regularly and results presented in a comprehensive report (Ballou et at., 1987). Ten year follow-up surveys were conducted in 1994 (Dodge et al., 1995). Ten years after dosing, sediment core analysis confirmed the presence of degraded hydrocarbons at both the crude oil and dispersed oil treatment sites. At the whole oil treatment, intertidal regions experienced further mortality in mangroves, while subtidal regions experienced few effects. At the dispersed oil treatment, subtidal corals, significantly impacted following initial treatment, appeared to have recovered. The present study is based on site visits during 2001-02', to the original crude oil, dispersed crude oil, and reference sites established in 1984. Despite the degradation of oil over the past 18 years, sheen is still visible leeching from non-dispersed, crude oil treatment sediments. Previously denuded intertidal mangrove regions currently carry a high sapling density, although recent offsite mangrove mortality may be indicative of continued toxicity and mobility of degraded hydrocarbons. Seagrass growth rates, highly variable at all sites over the duration of monitoring, appear to have been little influence by long-term treatment associated effects, while leaf area parameters at the crude oil treatment have significantly increased relative to the reference site. Sea grasses at the crude oil treatment and dispersed oil treatment both exhibit significantly reduced density relative to the reference site. Within coral zone parameters, current data reveal increased coverage of finger coral (Porites furcata) at the crude oil treatment. Since treatment, percent coverage of P. furcata has grown from 25.0%, in November 1984, to 63.5%, in June 2002. Seagrass and coral parameters are investigated for both between-site differences, and long-term within-site trends. Newly established parameters are investigated to help elucidate possible treatment effects.