Maen M. Husein

Adsorption of asphaltenes from heavy oil onto in situ prepared NiO nanoparticles

Removal of asphaltenes from heavy oil improves the quality of oil and makes it easier to process. To this end, Nassar et al. [1] recently showed that NiO nanoparticles have high affinity toward asphaltene adsorption. This investigation, however, involved toluene model solutions and commercially available nanoparticles. In the current work, we show that NiO nanoparticles prepared in situ within heavy oil display much higher affinity toward asphaltenes adsorption, and uptake in the order of 2.8 g asphaltene/g nanoparticles is reported. This uptake way exceeds asphaltene adsorption onto conventional porous adsorbents and commercial nanoparticles from toluene model solutions. Nanoparticle preparation followed a method developed by our group [2], and XRD, EDX, and TEM analyses confirmed the formation of NiO nanoparticles of 12±5 nm mean diameter. Kinetic experiments showed that, while equilibrium could be achieved in less than 2 h for both in situ prepared and commercial NiO particles, much higher adsorption took place onto the in situ prepared ones, owing to their better dispersion. Contrary to literature findings on adsorption from model solutions onto nanoparticles, surface coverage calculations revealed multilayer adsorption.

Nanoparticle Preparation Using the Single Microemulsions Scheme

Nanoparticles serve the need for advanced materials with specific chemical, physical, and electronic properties. These proper- ties can be attained by manipulating the particle size. Consequently, size control has been recognized as a key factor for selecting a nanoparticle preparation technique. (w/o) Microemulsions, or reverse micelles, have been successfully used to prepare wide variety of nanoparticles with controlled sizes. Studies showed that adjusting microemulsion and/or operation variables provides a key to controlling nanoparticle size and polydispersity. The effect of a given variable, however, relies heavily on the reactant addition scheme. The mixing of two microemulsions scheme has been widely used in the literature, and the effect of microemulsion and operation variables on inter- micellar nucleation and growth was detailed. The single microemulsions reactant addition scheme, on the other hand, enables intramicel- lar nucleation and growth, and therefore, may lead to a different response. Moreover, studies on nanoparticle preparation using the single microemulsions scheme involved more of reactive surfactants and introduced the concept nanoparticle uptake, which pertains to the maximum colloidal concentration of nanoparticles that can be stabilized in a microemulsion system. This review looks into the mecha- nisms controlling nanoparticle formation and compares literature trends reported for the effect of microemulsion and operation variables on the nanoparticle size and polydispersity for the single microemulsions reactant addition scheme. Moreover, it sheds some light on nanoparticle uptake and its significance.

Scavenging H2S(g) from oil phases by means of ultradispersed sorbents

Ultradispersed catalysts significantly enhance rates of reaction and mass transfer by virtue of their extended and easy accessible surface. These attractive features were exploited in this study to effectively capture H(2)S((g)) from an oil phase by ultradispersed sorbents. Sorption of H(2)S((g)) from oil phases finds application for scavenging H(2)S((g)) forming during heavy oil extraction and upgrading. This preliminary investigation simulated heavy oil by (w/o) microemulsions having 1-methyl-naphthalene; a high boiling point hydrocarbon, as the continuous phase. H(2)S((g)) was bubbled through the microemulsions which contained the ultradispersed sorbents. The type and origin of sorbent were investigated by comparing in situ prepared FeOOH and commercial alpha-Fe(2)O(3) nanoparticles as well as aqueous FeCl(3) and NaOH solutions dispersed in the (w/o) microemulsions. The in situ prepared FeOOH nanoparticles captured H(2)S((g)) in a chemically inactive form and displayed the highest sorption rate and capacity. Temperature retarded the performance of FeOOH particles, while mixing had no significant effect.

Removal of lead from aqueous solutions with sodium caprate

ABSTRACT Lead was removed from aqueous solutions by precipitation using sodium caprate [CH3(CH2)8COONa]. For a feed concentration of 7 mM (1450 ppm) lead and a mole ratio of caprate to lead of 2, the percentage removal of lead and the percentage loss of caprate were 99.5 ± 0.2 and 0.8 ± 0.3, respectively. The effects of pH and the concentrations of lead, calcium, chloride, and nitrate in the feed on the removal step were determined. At a mole ratio of caprate to lead of 2.0, the equilibrium concentrations of lead and caprate were independent of the feed concentration of lead. Decreasing the pH of the feed decreased the removal of lead but did not affect the loss of caprate. The presence of calcium, chloride, or nitrate in the feed did not affect the removal of lead. Sodium caprate was regenerated by adding HNO3 to the lead caprate precipitate to form capric acid from which sodium caprate was recovered by adding NaOH. Based on the amount of caprate used in the lead removal step, a percentage recovery of 98...

Removal of Heavy Metals from Aqueous Solutions by Precipitation-Filtration Using Novel Organo-Phosphorus Ligands

Abstract An organophosphorus mixture of sodium mono- and di-(n-hexa-decyl) phosphinate was synthesized and purified, and then used as a ligand to remove heavy metals by precipitation from aqueous nitrate, chloride, and sulfate solutions. The new ligand offers more advantages over the previously studied sodium dioctyl and dodecyl phosphinates. The sodium form of the mono- and di-(n-hexa-decyl) phosphinate has a much lower solubility in water, which contributed to much lower back contamination and much lower loss of the reagent, even when excess amount of ligand was employed. Moreover, an excess amount of the ligand did not alter the filtration characteristics of the resultant precipitate. The heavy metals: lead, cadmium, mercury, cobalt, and nickel were precipitated with the sodium mono- and di-(n-hexa-decyl) phosphinate, NaL, in the form of Pb L 2(s), Cd L 2(s), Hg L 2(s), Co L 2(s), and Ni L 2(s). In the absence of free acid in the feed, a maximum removal of each metal corresponded to the stoichiometric ratio. The residual concentrations of each of the metals at the optimum conditions were measured for the different media and found to be lower than 10 ppb, lower than the acceptable levels for most regions. Lead, as a model heavy metal, was studied in more detail. Adding an acid to the feed solution reduced the removal of lead as some of the phosphinate ligand was converted to the acid form. The presence of chloride and sulfate in the feed solution; up to mole ratios to lead of 5000, and of calcium in the feed solution; up to mole ratio to lead of 200, had no effect on the removal of lead. The ligand was more selective to lead than the other four metals, and the selectivity was in the order Pb > Cd > Co & Ni > Hg. The ligand was regenerated up to 99.99% and the metals were recovered in 100 times more concentrated aqueous solutions.

Nucleophilic substitution sulfonation in emulsions: effect of the surfactant counterion and different decyl halide reactants

Abstract The nucleophilic substitution reaction between sodium sulfite and different decyl halides was carried out in emulsions formed by the two-tailed cationic surfactants dioctyldimethylammonium chloride R 2 (Me) 2 N + Cl − or bromide R 2 (Me) 2 N + Br − . The oil phase of the emulsion consisted of the decyl halide reactant. The effects of R 2 (Me) 2 N + Br − concentration and different decyl halide reactants on the conversion were studied. A decyl chloride intermediate formed when decyl iodide or decyl bromide were reacted in R 2 (Me) 2 N + Cl − emulsions. The intermediate reacted further to the final product, sodium decyl sulfonate, at a rate which depended on the decyl halide reactant. The conversion to C 10 H 21 SO 3 Na versus R 2 (Me) 2 N + Br − concentration displayed a broad maximum. The reactivity of the decyl halides increased in the order: decyl chloride, bromide and iodide. Increasing decyl iodide concentration at a constant R 2 (Me) 2 N + Cl − concentration and a constant initial mole ratio of Na 2 SO 3 to C 10 H 21 I increased the reaction rate, while the conversion decreased. Plateaus in the conversions to C 10 H 21 SO 3 Na and C 10 H 21 Cl were reached for the run at 800 mM equimolar surfactant and reactant concentrations. The pseudophase ion exchange model, with the assumption of trapped amounts of the decyl halides within the emulsion oil core and thus not available for the reaction, described the experimental results.

Electrochemical Behavior of Potassium Ferricyanide in Aqueous and (w/o) Microemulsion Systems in the Presence of Dispersed Nickel Nanoparticles

The electrochemical behavior of the redox couple ferro/ferricyanide has been investigated in aqueous 1.0 M KNO3 and in (w/o) microemulsion using cyclic voltammetry (CV) and chronoamperometry (CA). The (w/o) microemulsion was composed of the non-ionic surfactant Tween-80, tetrabutylammonium perchlorate (TBAP) supporting electrolyte, HepTol, and dichloromethane as the continuous phase and the aqueous probe solution. In the aqueous supporting electrolyte solution of 1.0 M KNO3, the redox pair showed a reversible electrochemical behavior and followed Randles-Sevcik and Cottrell equations, however, with concentration-dependent diffusion coefficients. In the (w/o) microemulsion system, on the other hand, the probe showed an irreversible behavior mainly due to the adsorption of surfactant onto the working electrode, which hindered the charge transfer step. The presence of dispersed Ni nanoparticles in the aqueous solution did not have an effect on the electrochemical behavior of the redox couple, while it enhanced the reduction decay current in the (w/o) microemulsions. This observation was attributed to a more rapid charge transfer in a medium with inherently very low conductivity.

Wall slipping behavior of foam with nanoparticle-armored bubbles and its flow resistance factor in cracks

In this work, wall slipping behavior of foam with nanoparticle-armored bubbles was first studied in a capillary tube and the novel multiphase foam was characterized by a slipping law. A crack model with a cuboid geometry was then used to compare with the foam slipping results from the capillary tube and also to evaluate the flow resistance factor of the foam. The results showed that the slipping friction force FFR in the capillary tube significantly increased by addition of modified SiO2 nanoparticles, and an appropriate power law exponents by fitting FFR vs. Capillary number, Ca, was 1/2. The modified nanoparticles at the surface were bridged together and formed a dense particle “armor” surrounding the bubble, and the interconnected structures of the “armor” with strong steric integrity made the surface solid-like, which was in agreement with the slip regime associated with rigid surface. Moreover, as confirmed by 3D microscopy, the roughness of the bubble surface increased with nanoparticle concentration, which in turn increased the slipping friction force. Compared with pure SDBS foam, SDBS/SiO2 foam shows excellent stability and high flow resistance in visual crack. The resistance factor of SiO2/SDBS foam increased as the wall surface roughness increased in core cracks.

Effect on Fracture Pressure by Adding Iron-Based and Calcium-Based Nanoparticles to a Nonaqueous Drilling Fluid for Permeable Formations

This paper presents a comprehensive experimental evaluation to investigate the effects of adding iron-based and calcium-based nanoparticles (NPs) to nonaqueous drilling fluids (NAFs) as a fluid loss additive and for wellbore strengthening applications in permeable formations. API standard high-pressure-high-temperature (HPHT) filter press in conjunction with ceramic disks is used to quantify fluid loss reduction. Hydraulic fracturing experiments are carried out to measure fracturing and re-opening pressures. A significant enhancement in both filtration and strengthening was achieved by means of in situ prepared NPs. Our results demonstrate that filtration reduction is essential for successful wellbore strengthening; however, excessive reduction could affect the strengthening negatively.

Treatment of steam-assisted gravity drainage water using low coagulant dose and Fenton oxidation

The use of coagulation and Fenton oxidation was studied for total organic carbon (TOC) and silica removal from steam-assisted gravity drainage (SAGD) water at 80°C and two different concentrations replicating the stream feeding the warm lime softening unit having 675 mg/L TOC and 350 mg/L silica and the blowdown of the once through steam generator having 3700 mg/L TOC and 2585 mg/L silica. Coagulation was carried out by the addition of FeCl3, Al(NO3)3 or Ca(NO3)2. The results showed that Fe(III) salt outperformed Al(III) and Ca(II) salts. A two-stage addition of 2.5 g FeCl3 per g TOC intermediated by a filtration unit resulted in approximately 72% TOC removal and more than 80% silica removal while maintaining low solid waste. Comparing results pertaining to coagulant concentration and final pH, it can be easily concluded that silica removal is governed by the resultant pH, whereas TOC removal was accomplished through surface neutralization and localized enmeshment coagulation. Fenton oxidation is proposed to further treat the filtrate obtained from the second stage Fe(III) coagulation. An additional 10% TOC removal could be achieved; at seven times lower H2O2 dose in the presence of Fe 2+ or Fe0 reagent. Moreover, the advanced Fenton process resulted in high silica removal as a result of adsorption onto Fe(OH)3 precipitate, which formed at the equilibrium pH of the system.