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Polymer-induced drag reduction (DR) in fluids was studied using a rotational rheometer with double-gap concentric cylinder geometry. Although both polymers (polyacrylamide (PAM) and 2-acrylamido-2-methylpropane sulfonic acid (SPAM)) had molecular weights of several MDa, the contrasting polymer charge, nonionic and anionic, led to different polymer overlap concentrations (c*), PAM ≫ SPAM, and fluid rheology, with PAM fluids mostly Newtonian and SPAM fluids non-Newtonian (shear-thinning). Based on these differences, it was important to account for the infinite shear viscosity and normalize the polymer concentration by the intrinsic concentration (cint) so that the DR performance of the two polymer fluids could be accurately compared. Both polymers induced DR, and the maximum DR by SPAM (DR% = 28) was slightly higher than that by PAM (DR% = 22) when Rep ∼ 1700. For PAM, the loss of DR with time diminished at higher polymer concentrations (≥100 ppm, at Rep = 3149) but was found to be sensitive to high Rep, with polymer chain scission the likely cause of the reduced performance. For the semi-dilute SPAM fluids, the shear stability contrasted that of PAM, showing negligible dependence on the polymer concentration and Rep. The apparent rapid loss of DR was predominantly attributed to a time-dependent effect and not polymer degradation. In pipe flow, the maximum DR for SPAM was higher than that measured by rheometry and was attributed to differences in the flow conditions. However, changes in the normalized DR/c with polymer concentration were found to be consistent between the two flow geometries. Furthermore, the high fluid stresses in pipe flow (at high Rep) led to drag reduction losses consistent with PAM, as the time-dependent effect was not seen.

Magnetic nanoparticles have been successfully used to recovery oil from oil spilled on water. Two different methods, floating and vortex, were employed to promote the interaction of four oil samples with different API (e.g., 10, 20, 28 and 45) spilled on seawater and deionized water with three magnetic materials, namely: magnetite nanoparticles (N); magnetic nanocomposites of yeast biomass provided by ethanol industry (Y); and magnetic nanocomposites of cork powder (C). The magnetic nanomaterials exposed to oil on water were taking out by a neodymium magnet, and the oil recoveries were determined by gravimetric analysis before and after lyophilization. The lyophilization was determinant to guarantee the accuracy of the experiments, and without this step, the masses of oil recovered would be overestimated due to the drag of water during the oil and magnetic material removal process. Three main factors, API, contact method and magnetic material, and two interactions (i.e., API × contact method, and contact method × magnetic material) presented a statistically significant effect on oil recovery. It was observed that oil recovery increases as API decreases, and it was possible to establish a model to predict the amount of recovered oil according to this effect. Higher oil recoveries were also obtained by magnetic nanocomposites of yeast biomass (Y), regardless of the contact method and type of water, recoveries of 23% and 100% for 45 and 10 API, respectively, employing around 20 mg of Y on 300 mg of spilled oil. These percentages correspond to 0.29 ± 0.01 kg/kg and 15.98 kg/kg of recovering oil by the magnetic procedure. The increase of mass of magnetic material improved the recovery of oils with higher APIs. The reusability of the spent materials presents potential for its application in oil spill cleaning technologies.

Pharmaceutical compounds are emerging contaminants that have been detected in surface water across the world. Because conventional wastewater treatment plants are not designed to treat such pollutants, new technologies are needed to degrade and oxidize such contaminants. The newly developed oxy-cracking process was utilized to treat the antidiabetic drug, metformin. The process, which involved partial oxidation of metformin in alkaline aqueous medium, proved to decompose the drug into small organic molecules, with minimum emission of CO2, therefore, increasing its biodegradability and removal from industrial treatment plants. The reaction gaseous products were probed by online gas chromatography. The liquid phase before and after oxy-cracking was analyzed for total carbon content by TOC and gas chromatography mass spectrometry. The products formed from the nitrogen-rich drug included ammonia, amines, amidines, and urea derivatives. A reaction mechanism for the oxy-cracking process is proposed. Because the hydroxyl radical (˙OH) is believed to play a central role in the oxy-cracking process, the mechanism is initiated by ˙OH attacks on metformin, followed by single decomposition or isomerization steps into stable products. The reactions were investigated using density functional theory calculations and validated using high quality 2nd order Moller–Plesset perturbation theory energy calculations.

Oil spill is a serious environmental concern, and alternatives to remove oils from water involving biosorbents associated to nanoparticles is an emerging subject. Magnetite nanoparticles (MNP) and yeast magnetic bionanocomposite (YB-MNP) composed by yeast biomass from the ethanol industry were produced, characterized, and tested to remove new motor oil (NMO), mixed used motor oil (MUMO) and Petroleum 28 °API (P28API) from water following the ASTM F726–12 method, which was adapted by insertion of a lyophilization step to ensure the accuracy of the gravimetric approach. Temperature, contact time, the type and the amount of the magnetic material were the parameters evaluated employing a fractional factorial design. It was observed the removal of 89.0 ± 2.6% or 3522 ± 118 g/kg (NMO) employing MNP; 69.1 ± 6.2% or 2841 ± 280 g/kg (MUMO) with YB-MNP; and 55.3 ± 8.2% or 2157 ± 281 g/kg (P28API) using MNP. The temperature was the most significant parameter in accordance with the Pareto's graphics (95% confidence) for all oil samples considered in this study as well as the two magnetic materials. Contact time and the interaction between the materials and temperature were also relevant. The D-Optimals designs showed that the NMO and P28API responded in a similar way for all evaluated parameters, while the uptake of MUMO was favored at higher temperatures. These behaviors demonstrate the influence of oil characteristics and the intermolecular forces between the oil molecules on the mechanism dragging process performed by the attraction between magnetite nanoparticles and a 0.7 T magnet. It was clear that this kind of experiment is predominantly a physic phenomenon which cannot be described as adsorption process.

This study focuses on detailed characterizations of asphaltene fractions extracted from the Algerian Hassi-Messaoud oil field. It was found that the extracted asphaltenes are not completely soluble in toluene, instead two fractions of asphaltenes were obtained upon solubilizing the heptane-precipitated neat asphaltenes in toluene. Extensive characterizations of the toluene-soluble and insoluble fractions were carried out using elemental analysis, Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and solid-state nuclear magnetic resonance (ssNMR). It was suggested that the high oxygen content and uneven compositional structures are the main contributors to asphaltene instability. The toluene-insoluble fractions were found to have higher polarity and aromaticity as well as more oxygen content than the neat asphaltenes and toluene-soluble fractions.

In this study, a fixed-bed column adsorption process was employed to remove organic pollutants from a real industrial wastewater effluent using polyethylenimine-functionalized pyroxene nanoparticles (PEI-PY) embedded into Diatomite at very low mass percentage. Various dynamic parameters (e.g., inlet concentration, inlet flow rate, bed height, and PEI-nanoparticle concentration in Diatomite, (%nps)) were investigated to determine the breakthrough behavior. The obtained breakthrough curves were fit with a convection-dispersion model to determine the characteristic parameters based on mass transfer phenomena. The axial dispersion coefficient (DL) and group of dimensionless numbers; including Renold number (Re), Schmidt number (Sc), and Sherwood number (Sh) were all determined and correlated by Wilson-Geankoplis correlation that was used to estimate the external film diffusion coefficients (Kc) at 0.0015

Adsorption of propionic acid (PA) onto silica-embedded NiO/MgO nanoparticles (i.e., SiO2-NiO, SiO2-MgO, and SiO2-(Ni0.5Mg0.5)O) was investigated experimentally and theoretically by carrying out computational modeling through molecular mechanics, density functional theory (DFT) calculations, and molecular dynamics (MD) simulations. The experimental adsorption isotherm fit well to the Sips model with a heterogeneity factor between 0.2 and 0.5 in most cases, indicating a heterogeneous adsorption system. SiO2-NiO nanoparticles showed the highest uptake on a normalized surface area basis due to its stability in aqueous solutions. Moreover, the results of thermodynamic studies, namely, changes in Gibbs free energy ( Δ G ads ∘ ) and standard enthalpy ( Δ H ads ∘ ), confirmed that the adsorption is spontaneous and exothermic in nature, respectively. Furthermore, computational modeling of the molecular interaction between the PA molecule and the nanoparticle surfaces of both NiO and MgO were implemented to address the adsorption behavior comprehensively. Interestingly, in vacuum media, the computational modeling and DFT calculations showed that MgO favored the PA molecule adsorption stronger than the NiO, contrary to what observed experimentally. MD simulations counted the presence of water molecules and provided more linkable results to the ones observed experimentally. Eventually, by having a meticulous eye of the equilibrated structures of PA molecules at the NiO-water interfaces according to the MD simulation, we could confirm theoretically the maximum adsorption capacity for complete monolayer coverage with the one obtained experimentally which was around 2.8 (molecules/nm2).

In this study, polyethylenimine-functionalized pyroxene nanoparticles (PEI-PNPs) were embedded into Diatomite (D4500), a commonly used filter aid, at

In this study, polyethylenimine-functionalized pyroxene nanoparticles were successfully prepared in-house for the removal of commercial red dye (CRD) from an industrial wastewater. The functionalization was accomplished by anchoring polyethylenimine (PEI) onto the surface of pyroxene nanoparticles without surface modifications or preliminary coating. Characterization was followed out by textural properties, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), infrared (IR) spectroscopy, and thermogravimetric analysis (TGA). The prepared nanoparticles were successfully functionalized by the PEI and portrayed granulated-like morphologies with average crystaline domain sizes around 10 nm and BET surface area (∼18 m 2 /g) that increased reasonably to ∼119 m 2 /g by drying using lyophilizing method instead of conventional drying of the synthesized materials. The prepared PEI-PNPs showed an excellent adsorption capacity (∼340 mg/g) and fast adsorption kinetics (

The nanosize effects of NiO nanosorbcats on adsorption and post-adsorption catalytic thermo-oxidative decomposition of vacuum residue (VR) n-C5 asphaltenes was investigated using a UV-vis spectrophotometer and thermogravimetric analyzer coupled with a mass spectrometer and presented in this study. Sizes between 5 and 80 nm of different-sized NiO nanosorbcats were employed. Batch adsorption experiments were carried out for the considered asphaltenes in toluene solutions, monitored via UV-vis spectrophotometry. The macroscopic adsorption isotherms were described by implementing the solid-liquid equilibrium (SLE) model. The findings showed that thermally cracked vacuum residue (VR) n-C5 asphaltenes interact to different extents with different-sized NiO nanosorbcats. A normalized surface area basis was used for the amount of VR n-C5 asphaltene adsorbed per nm2 of NiO surface, which was the highest for NiO nanoparticles of size 80 nm, with 5 nm size being the lowest. Thermogravimetric analysis of VR n-C5 asphaltenes was also achieved and the reaction products were explored by a mass spectrometer. The Kissinger-Akahira-Sunose (KAS) isoconversional model was used to describe the reaction mechanism and to confirm the validity of the catalytic role of the different particle sizes of NiO nanosorbcats. The highest catalytic activity was for smallest NiO when compared to the highest NiO nanosorbcats. Furthermore, the results of thermodynamic transition state parameters of activation; changes in Gibbs free energy (ΔG‡), entropy (ΔS‡), and enthalpy (ΔH‡) highlighted the catalytic activity of NiO nanosorbcats towards VR n-C5 asphaltenes oxidation. These findings exhibit the significance of textural properties and nanosize of nanoparticles during adsorption and thermal catalytic processing of asphaltenes. This article is protected by copyright. All rights reserved

Achieving affordable and clean water is one of the greatest global challenges of this century. This is due to the enormous upsurge in the world's population, yet at the same time, the scarcity of fresh water. Far more than that, some regions are awash in fresh water while other regions are afflicted by drought. Accordingly, new technological approaches should be brought to the forefront to tackle the water problem. Hence, this study presents three types of newly in-house prepared silica-embedded NiO and/or MgO nanoparticles, namely; SiO2–NiO, SiO2–MgO, and SiO2–(Ni0.5Mg0.5)O. The properties of these nanoparticles were characterized using XRD, BET, HRTEM, CO2-TPD, and IR spectroscopy. These nanoparticles are applied for the first time to adsorptive removal of different cationic and anionic model organic molecules with different functionalities, namely: methylene blue (MB), neutral red (NR), and acid red 27 (AR27), mimicking pollutants existing in wastewater effluents. It has been found that on a normalized surface area basis, the number of cationic model molecules adsorbed per nm2 of the SiO2–(Ni0.5Mg0.5)O nanoparticles were the highest suggesting the possible synergistic effect between Ni and Mg in the mixed oxide, however, SiO2–NiO showed the highest uptake for the anionic case due to its stability in aqueous solutions. The experimental adsorption isotherms fit well to the Sips model for MB and AR27 indicating a heterogeneous adsorption system. However, a multilayer adsorption behavior was obtained for NR which has been described by the BET model. Computational modeling and DFT calculations of the interaction between the model molecules and the surfaces of the prepared nanoparticles were carried out to get more mechanistic insights into their adsorptive behaviors. The results showed that the adsorbed molecules tend to lie flat on the surface of the materials except for NR which tends to be adsorbed slightly tilted when compared with the others. Additionally, molecular dynamics simulation was performed to gain additional insights into the adsorption behavior of NR in the presence of water. The evolved profile of total energy of the system as a function of simulation time emphasized the eccentric BET adsorption behavior of NR onto these novel nanoparticles.

espanolResumen En este trabajo, se desarrollo un estudio de la adsorcion/desorcion de asfaltenos a bajas y altas concentraciones (100 - 30000 mg/L) incluyendo el efecto del tamano de particula del adsorbente (nano y microsilice), efecto de la presion, de la temperatura y el tipo de solvente. Las pruebas de adsorcion/desorcion en las diferentes superficies de silice se realizaron mediante pruebas por lotes usando espectrofotometria UV-vis y analisis termogravimetricos. Debido a sus especiales caracteristicas de alta area superficial y dispersabilidad, las nanoparticulas de silice adsorben una mayor cantidad de asfaltenos que la silice microparticulada. Ademas, se observo que la desorcion de los asfaltenos de las nanoparticulas de silice fue significativa, mientras que para el sistema microparticulado fue insignificante, sugiriendo un mayor potencial de adsorcion para la silice microparticulada. La cantidad de asfaltenos adsorbidos aumento al incrementar la presion, al mismo tiempo que disminuye al aumentar la temperatura del sistema. Tambien, los resultados obtenidos demuestran que el tipo de solvente juega un papel importante en el proceso de desorcion de los asfaltenos. Adicionalmente, se realizaron pruebas de humectabilidad para las nanoparticulas de silice en presencia y en ausencia de asfaltenos adsorbidos y se evidencio que incluso a altas cantidades adsorbidas, las nanoparticulas mantienen su condicion humectable al agua. EnglishAbstract In this work, a study of the adsorption/desorption of n-C7 asphaltenes at low and high concentrations (100 - 30000 mg/L) was performed for which the effects of adsorbent particle size (nano and microsilica), pressure, solvent, and temperature were evaluated. Adsorption/desorption tests on different silica surfaces were performed in batch-mode using UV-vis spectrophotometry and thermogravimetric analyses. Owing to its high surface area and dispersibility, nanosilica adsorbed higher quantities of n-C7 asphaltenes than microsilica. Asphaltene desorption from nanosilica surface was significant, while the desorption from microsilica surfaces was insignificant, suggesting a higher adsorption potential for the latter. Asphaltene adsorption increased with pressure and decreased with temperature. Type of solvent plays a significant role on the asphaltene desorption. The wettability tests for virgin nanosilica and nanosilica contained adsorbed asphaltenes showed that even at high asphaltene loading, the nanoparticles maintained its water-wet nature. portuguesResumo Neste trabalho foi realizado um estudo sobre a adsorcao/dessorcao de asfaltenos n-C7 em concentracoes altas e baixas (100 - 30000 mg/L) no intuito de avaliar os efeitos do tamanho da particula adsorvente (nano e microsilica), pressao, solvente e temperatura. Testes de adsorcao/dessorcao em diferentes superficies de silica foram realizados em serie utilizando analises termogravimetricos e de espectrofotometria UV-vis. Vista sua grande area de superficie e capacidade de dispersao, a nanosilica adsorveu maiores quantidades de asfaltenos n-C7 do que a microsilica. A dessorcao de asfalteno da superficie da microsilica foi insignificante, isso sugere a existencia de um maior potencial de adsorcao para a microsilica. A adsorcao de asfalteno aumentou com a pressao e diminui com a temperatura. O tipo de solvente tem um papel preponderante na dessorcao de asfalteno. Os testes de molhabilidade para nanosilica virgem e asfaltenos adsorvidos com conteudo de nanosilica mostraram que mesmo durante uma carga alta de asfaltenos, as nanoparticulas preservaram sua natureza de humidade-agua.

In this study, the thermal oxidation of an asphaltene model molecule, Quinolin-65, was investigated using the density functional theory (DFT) and the second-order Moller–Plesset (MP2) perturbation theory. The reactions studied involved thermal decompositions as well as the interactions between the model molecule and singlet atomic (O1D) and molecular (O21Δ) oxygen. The theoretical study was performed under conditions similar to those of the uncatalyzed thermal oxidation of asphaltenes. A new reaction pathway for the loss of the olefin chain in Quinolin-65 via a 1,3-hydrogen shift mechanism was revealed. Thermogravimetric analysis of Quinolin-65 was also performed and the reaction products were probed by a mass spectrometer. Both the theoretical study and the thermogravimetric analysis concluded that the thermo-oxidative decomposition of Quinolin-65 is a complex multi-step reaction process, which involves different reaction pathways. The thermodynamic parameters obtained in this study showed that the reaction process should start with the loss of the olefin chain in the Quinolin-65 molecule, followed by the oxidation of the aromatic chain, to produce mainly, H2O, CO2, and SO2.

This study presents new environmentally sound and low-cost yet highly efficient pyroxene (NaFeSi2O6, PY), known as aegirine, nanoparticles. They are applied for the first time for the adsorptive removal of violanthrone-79 (VO-79) which was selected as a model-adsorbing compound to mimic polar heavy hydrocarbons. PY nanoparticles are prepared by a low temperature hydrothermal synthesis route. Controlled particle sizes of PY nanoparticles were synthesized in the range between 1 and 100 nm. Moreover, the surface and structure of the PY nanoparticles were modified by partially replacing some of the original atoms, like Na, Fe or Si, by Ce, Zr, Ni, Ca and H to enhance their adsorption capacity towards VO-79. One nanoparticle size was prepared at different synthesis heat-treating times to investigate the stability of the nano-adsorbent. It has been found that PY nanoparticles with particle sizes in the range between 30 and 60 nm have the highest adsorption capacity and affinity towards VO-79. The adsorption capacity of the VO-79 over functionalized PY nanoparticles was increased significantly in the order of PY–H > PY–Ca > PY–Ni > PY–Ce > PY–Zr, when compared with unmodified PY nanoparticles. Varying the heat-treating time of synthesis of PY nanoparticles did not affect their size stability and surface properties. Moreover, no significant increase towards VO-79 adsorption uptake was detected. The experimental macroscopic adsorption isotherms fit well to the Sips model, indicating a heterogeneous adsorption system.

This study aims to evaluate the effects of resin I on the n-C7 asphaltene thermal decomposition under an oxidative atmosphere in the presence of hybrid nanoparticles (SNi1Pd1) of NiO and PdO supported over fumed silica nanoparticles. Resin I and n-C7 asphaltenes were characterized by elemental analyses, thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). The adsorption of resin I and n-C7 asphaltenes was evaluated using heavy oil model solutions through a combined method of thermogravimetric analysis and softening point measurements. Adsorption isotherms were measured for individual resin I and n-C7 asphaltene samples as well as for different n-C7 asphaltene to resin I ratios of 7 : 3, 1 : 1 and 7 : 3. For the first time, competitive adsorption of n-C7 asphaltene and resin I on functionalized nanoparticles with NiO and PdO is assessed. The oxidation tests were carried out in an air atmosphere for a specific n-C7 asphaltene loading in each sample (ca. 0.20 ± 0.02 mg m−2). In this order, for samples adsorbed from different A : R ratios of 7 : 3, 1 : 1 and 3 : 7, the amounts of resin I adsorbed were 0.06, 0.10 and 0.20 ± 0.01 mg m−2, respectively. Hence, the A : R ratios in the adsorbed phase were 10 : 3, 2 : 1 and 1 : 1. The catalytic effect was measured through thermogravimetric analysis coupled to Fourier transform infrared spectroscopy, which evaluated the effluent gases of the catalytic oxidation process. The adsorption isotherms were modeled using the solid-liquid-equilibrium (SLE) model, and the effective activation energies for the oxidation process of the adsorbate were calculated through the non-linear integral method of Vyazovkin (NLN). As a result, it was observed that the temperature of n-C7 asphaltene decomposition did not vary significantly with the inclusion of resin I in the system. Rate of mass loss curves showed that the main peak temperatures of n-C7 asphaltenes and resin I decreased drastically from approximately 500 °C to 250, 260 and 270 °C for resin I loadings over SNi1Pd1 nanoparticles of 0.20, 0.10 and 0.06 mg m−2, respectively. However, the catalytic effect of the nanoparticles was indeed affected, as revealed by the increase in the estimated effective activation energy as the amount of resin I in the system increased. It is expected that this work opens a better outlook about the use of catalytic nanoparticles in the oil and gas industry, mainly in improved (IOR) or enhanced oil recovery (EOR) processes for heavy and extra-heavy oil upgrading.

In this study methylene blue (MB) has been investigated for its adsorption and subsequent catalytic thermo-oxidative decomposition on surface of maghemite (γ-Fe2O3) nanoparticles. The experimental adsorption isotherm fit well to the Freundlich model, indicating multi-sites adsorption. Computational modeling of the interaction between the MB molecule and γ-Fe2O3 nanoparticle surface was carried out to get more insights into its adsorption behavior. Adsorption energies of MB molecules on the surface indicated that there are different adsorption sites on the surface of γ-Fe2O3 confirming the findings regarding the adsorption isotherm. The catalytic activity of the γ-Fe2O3 nanoparticles toward MB thermo-oxidative decomposition has been confirmed by subjecting the adsorbed MB to a thermo oxidation process up to 600 °C in a thermogravimetric analyzer. The experimental results showed a catalytic activity for post adsorption oxidation. The oxidation kinetics were studied using the Ozawa-Flyn-Wall (OFW) corrected method. The most probable mechanism functions were fifth and third orders for virgin MB and MB adsorbed onto γ-Fe2O3 nanoparticles, respectively. Moreover, the results of thermodynamic transition state parameters, namely changes in Gibbs free energy of activation (ΔG(‡)), enthalpy of activation (ΔH(‡)), and entropy of activation (ΔS(‡)), emphasized the catalytic activity of γ-Fe2O3 nanoparticles toward MB oxidation.

The drug metformin is the most prescribed drug to treat type II diabetes and has been recently reported to have anticancer activities. Because of its wide use, its potential risk on the environment is extremely concerning. In this study, the mechanism and the thermodynamics of the thermo-oxidative decomposition of the metformin were investigated as part of a new solution for the pharmaceutical contamination of water bodies. Thermogravimetry and mass spectrometry were used to demonstrate the metformin thermo-oxidative decomposition under air in the temperature range 25–800 °C. The isoconversional methods of Kissinger-Akahira Sunose (KAS) and Friedman (FR) were implemented to deduce the trends of effective activation energies. As expected, the effective activation energy (Eα) of the reaction was dependent on the reaction temperature, suggesting multi-step reactions. The Eα ranged from 100 to 145 kJ/mol and 200–300 kJ/mol for the KAS and FR methods, respectively. The kinetic triplet, Aα, ΔS‡, and ΔG‡ were also determined by finding the appropriate reaction model. Theoretical calculations were implemented to propose a full reaction mechanism. The oxidation of metformin was investigated with both molecular O2(t) and atomic O(t) oxygen. The experimental results were then explained under the light of the computational data to explain the variation of Eα with temperature, and the competition between the O2(t)/O(t) species.

The oil industry faces economic and environmental challenges due to its energy- and water-intensive processes. Surplus residual feedstocks and the water produced via heavy oil upgrading and processing are among the most challenging problems in the oil industry. Utilization these waste materials and a lack of efficient technologies to treat them are the main challenges causing the industry to consider them as waste materials. Existing technologies only add a small value, require high capital investment, and generate high greenhouse gas emissions. Therefore, in this study, we review and highlight the major findings regarding the oxy-cracking process, which is introduced as an alternative beyond combustion, as an environmentally friendly technique for converting these feedstocks into value-added products and also enhances the recyclability of wastewater. Through these residual feedstocks are partially oxidized in basic aqueous media at mild operational temperatures (150–230 °C) and pressures (3.4–5.2 MPa). Several operating conditions have been reported to optimize the conversion and selectivity of the products, and the results showed that the temperature and residence time have significant impacts on the yield and environmental impact. The experimental findings were validated with theoretical calculations, which provided insights on understanding the kinetic behavior based on the radical mechanism. The characterization findings revealed that the oxy-cracking could be a platform for a wide range of products such as humic acids, clean fuel, and carbon nanomaterials, and to recover valuable metals. Moreover, this process could be implemented for treatment of oil sand processes affected water and for decomposing emerging pharmaceuticals.

A commercial filter aid material of Diatomite was modified via loading it with a low mass fraction of polyethylenimine-functionalized pyroxene nanoparticles (PEI-PNs) to enhance its adsorption activities. The modified Diatomite was then used for Cr(VI) removal from dichromate solution and from real tannery wastewater. For the synthetic wastewater, batch adsorption experiments were first performed at various pH and Cr(VI) initial concentrations. Then, the obtained kinetic parameters were used to investigate the continuous adsorption inside the fixed-bed column. The continuous removal of the Cr(VI) was performed inside a fixed-bed column under various influent flow rates, Cr(VI) initial concentrations, and bed-heights. In the column experiments, high adsorption of Cr(VI) was observed at low flow rates, high bed heights, and low influent initial concentrations. A dimensionless form of the advection-axial dispersion model, featuring Peclet number as a fitting parameter, was then used to study the breakthrough behavior under various dynamic parameters. Afterward, the modified Diatomite was used to remediate well characterized real tannery wastewater. For the treatment of the tannery wastewater, our modified filter aid, compared with the non-modified one, showed an outstanding performance and a higher removal efficiency.

In the last decade, traces of pharmaceutical and personal care products (PPCPs) in the nano and microgram per litre range have been reported in the water cycle; this includes surface water, wastewater, groundwater, and to a lesser extent drinking-water. Their presence in water, even at low concentrations, has raised concerns among drinking-water regulators, governments and water suppliers, regarding the potential risks to human health from exposure to traces of pharmaceuticals via drinking-water. Metformin (MF) and its transformative product, guanyl-urea, are expected to be present in aquatic environments, due to their global consumption rate. Not surprisingly, guanylurea has also been detected in surface water, groundwater, and drinking water. The toxicological studies showed that availability of MF might cause ecotoxicological effects, which suggests that MF is a potential endocrine disruptor and thus further emphasising the threat this drug could pose to our environment. Thus, many treatment methods have been suggested by many investigators to reduce the high levels of MF. Adsorption with some novel materials, for instance, showed great potential in removing MF from water in the batch processes, while very limited investigation has been done in continuous mode. Therefore, an effective adsorption process should be well implemented with use of efficient adsorbent for MF removal from water. Herein, MF adsorptive removal from water by amorphous silica-alumina (SA) composite was carried out in a fixed-bed column under the influence of various dynamic conditions (i.e., inlet solution pH, initial concentration of MF, initial flow rate, and bed-height). Initially, batch adsorption experiments were conducted to determine the adsorption kinetic parameters. Then, the obtained kinetic parameters were used to investigate the continuous adsorption inside the fixed-bed column. In the column experiments, high adsorption of MF was obtained at low flow rate, high bed height, low influent concentration, and high pH. Breakthrough behavior under the influence of various dynamic parameters was also investigated using the advection-axial dispersion model, incorporating surface and intra-particle diffusion theory to identify the key process parameters controlling the rate of adsorption. Furthermore, the unused bed length (HUNU) approach was also employed to determine the best utilization conditions for the column by correlating the unused bed (inactive zone) fraction (FH) from the column with axial Peclet number (Pex).

Oxy-cracking has been developed recently as an effective technology for converting residual feedstocks, like petroleum coke (petcoke), into valuable commodity products. This offers a new pathway for creating valuable products from solid waste hydrocarbon via oxygen incorporation onto the aromatic edges, where the oxy-cracked petcoke becomes soluble in water as oxygenated hydrocarbons. This fact enhances the tendency of petcoke to disaggregate, crack and convert into humic acid analogs, making them a valuable product at low temperatures. For practical purposes, and to favor high conversion and selectivity towards valuable product, energy consumption and capital investment should be minimized. In addition, low selectivity to CO2 emission is required to meet the global environmental regulations. Hence, introducing suitable heterogeneous catalysts to the oxy-cracking process could enhance the process conversion and selectivity. Therefore, in this study, a copper-silicate (CaCuSi4O10) material with nanocrystalline domains was introduced to enhance the selectivity and conversion of the oxy-cracking reaction of petroleum coke. The copper-silicate was synthesized in-house and characterized using BET, SEM, FTIR and XRD analyses. The catalytic activity of the prepared material was investigated by cracking the residual feedstock in an alkaline medium. The results showed that the catalyst enables the reaction to occur at a lower temperature with higher conversion as compared with the non-catalyzed reaction. An insignificant amount of CO2 was formed in the gas and liquid phases at high temperature as confirmed by GC and TOC analyses, respectively. The triangular lump kinetic model was implemented to describe the reaction pathways. The oxy-cracked products were found to be in the form of humic acid analogs with different contribution of the functionality groups such as carboxylic, carbonyl, and sulfonic acids as confirmed by FTIR analysis.

This study provides a detailed O-exchange of Ce-MFI, Ni-MFI and Ce-Ni-MFI using isotopic water (50% H218O - 50% H216O) to better understand the reaction mechanism of the catalytic water gas shift reaction (WGSR) over different combinations of Ni and Ce incorporated in the MFI structure. The study showed high activity of incorporated Ce on water splitting, and explained how adding Ce to Ce-Ni-MFI as a catalyst in the WGSR increased its performance and selectivity. A detailed kinetic study was performed at low temperatures (503–533 K) on Ce-Ni-MFI (with 2 wt% Ni and 2 wt% Ce) using empirical, microkinetic and neural networks techniques. All these methods predicted the reaction rate very well. The suggested reaction mechanism from the microkinetic approach was consistent with the findings of the O-exchange study, and showed the cooperation of Ni and Ce to provide the required oxygen to oxidize CO on the Ni surface.

A possibility of low temperature catalytic steam gasification of n-C5 asphaltenes mixed in light cyclic oil (LCO) in a fixed bed reactor is tested and presented. Four meta kaolin based catalysts containing one alkali (K or Cs), one alkaline earth (Ca or Ba) metal oxides were characterized and tested. Two of these four catalysts also contained NiO nanoparticles in addition to alkali and alkaline earth metal oxides. Addition of sugar as a porogen to kaolin created meso as well as macroporosity. These mesoporous–macroporous meta kaolin based materials are intended to work mainly as catalysts for steam gasification of the adsorbed asphaltenes. XRD data showed presence of Ni3S2 in the spent catalyst. It was found that low temperature catalytic steam gasification was possible by all four catalysts. However, replacement of Ca by Ba increased H2 production. Also, incorporation of NiO nanoparticles promoted further H2 production during the steam gasification of the adsorbed asphaltenes, leading to CO2 and H2 as major products with less side reactions. Of the two nickel-based catalysts, 3NiO6Cs6Ba seems to be the more promising material, with slightly lower activation energy, and higher production of gases per mole of metal contained in the catalyst.

Magnetic iron-oxide nanoparticles exhibit high efficiency in wastewater treatment for many important reasons, including that they can remove contaminants from wastewater rapidly owing to their high external surface area/unit mass and interstice reactivity. Additionally, this type of iron oxide can easily be separated using a magnet after finishing the treatment process, can be used as a catalyst for the decomposition of adsorbed contaminants and thus reduce sludge formation, and can cost-effectively meet the environmental regulations for wastewater treatment since it can be prepared in situ where treatment is needed via various techniques. In this study, we use magnetic iron oxide nanoparticles for dye removal from synthetic and real textile wastewater for the first time. The effects of different experimental parameters on dye removal, such as contact time, initial concentration, solution pH, and coexisting ions, were investigated. Computational modelling of the interaction of different dye molecules with different surfaces of γ-Fe2O3 nanoparticles is performed to obtain more mechanistic insights on the adsorption behaviour. The results showed that dye adsorption was fast, as external adsorption was dominated. The adsorption equilibrium data fit very closely to the Langmuir adsorption isotherm model, confirming monolayer adsorption, which is supported by the adsorption computational calculations. The adsorption was spontaneous, endothermic, and physical in nature.

In this study, two dicationic asymmetrical diamine/copper(II) nitrate salt complexes of the general formula trans-[CuII(NN')(2)center dot H2O](NO3)(2) were successfully synthesized using N,N-dimethylethylenediamine and N,N-diethylethylenediamine as asymmetrical diamine ligands. The structure of complex 2 was identified by X-ray single crystal diffraction analysis confirming that the bidentate ligand N,N-dimethylethylenediamine forms a penta-coordinated complex with an H2O molecule located around the copper(II) ion in a trans configuration. It was found that the metal centre is coordinated in a distorted square pyramidal fashion with a tau value of 0.274. The desired complexes were fully characterized using, MS, UV-Vis, CV, FTIR, TG/DTA, and Hirshfeld surface computational analysis. High level theoretical calculations were also performed in order to investigate the complexes structure, conformers, vibrational frequencies, and their excited states., The authors would like to extend their sincere appreciation to the Deanship of Scientific Research at King Saud University for funding this Research group NO (RG -257-1436-1437). The authors are also grateful to the Western Canada Research Grid., info:eu-repo/semantics/publishedVersion

The presence of water in coal presents a technological challenge for its industrial use in energetic processes. Water tends to negatively affect the coal quality and its net heating value (NHV), in addition to affecting its transportation costs. Therefore, this study aims to investigate the effects of glycerol and temperature on water adsorption onto systematically modified coals. A Colombian bituminous coal sample was used as support for being modified with glycerol. The virgin coal and modified coal were characterized by nitrogen adsorption at 77 K (SBET), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, elemental analysis (C–H–N elemental), and thermogravimetric analysis (TGA). The results showed that the water uptake decreased as the amount of glycerol on the coal surface increased. The optimum concentration of 8 wt% of glycerol impregnated on the coal minimized water adsorption. Over a range of water activity evaluations, this amount of glycerol (C8) reduced water adsorption by approximately 60% compared with nonimpregnated coal (C0). As expected, water uptake decreased with increasing temperature. These results are reflected in the NHV with an increase of 17% for the C8 sample compared with the other samples evaluated. The Talu and Meunier model was used to fit the experimental adsorption isotherms, and the mean square root error (MSRE%) was lower than 10%. The isosteric heat of sorption (IHS) for coal tends to decrease as the amount of adsorbed water increases. In addition, the value of IHS decreases as the concentration of glycerol increases due to the blocking of polar adsorption sites present on the coal surface, which are the main regions of low uptake of adsorbed water. Additionally, the Gibbs free energy was found to have negative values, which corroborates the spontaneous adsorption process.

Olive mill wastewater (OMW) is an environmental concern that has been highlighted as a serious environmental problem in the Mediterranean basin countries because of its high organic load and phytotoxic and antibacterial phenolic compounds, which resist biological degradation. Consequently, this type of wastewater represents a huge challenge for the conventional wastewater treatment techniques as it can impact the lifetime of bacteria needed for the treatment. Iron-oxide nanoparticles are attractive for wastewater treatment for two important reasons. First, nanoparticles can remove pollutants from wastewater rapidly. Second, this magnetic type of nanoparticles could be separated easily using a magnet after finishing treatment process. In this study, we aimed at investigating the effectiveness of the magnetic iron oxide nanoparticles in the removal of large organic contaminants from OMW. Batch and continuous mode processes were applied on OMW treatment to determine the effect of contact time, solution pH, coexisting contaminants and the adsorption isotherm. The results showed that the adsorption was fast and the adsorption reached equilibrium within less than 30 min. The adsorption equilibrium data fit very well to the Brunauer–Emmett–Teller (BET) Model, indicating multi-layers adsorption. The adsorption of major pollutants was associated to an efficient removal of coexisting contaminants such as heavy metals and free ions. The adsorption of OMW pollutants was dependent on pH of the solution. Finally, continuous-mode process was tested successfully using a packed bed column that combined sand filtration with magnetic nanoparticles to decolourize OMW effluent. This study will provide valuable insight on the effect of nanoparticles toward the treatment and recyclability of olive mill wastewater, which is crucial for the local olive mill industry. After seeing the successful achievement of integrating nanoparticles with fixed bed filtration, a preliminary process description and cost estimation of stand-alone plant (with a capacity of 4 m 3 /h) for OMW treatment were considered in this study. Process capital and annual operating costs were estimated to be $12,306 and $476/year, respectively.

With more than 170 billion barrels of estimated oil sands reserves in Canada, Canada has the third largest oil reserves in the world. However, more than 80% of oil sand’s reserves are located deep underground and could not be accessed by surface mining. Nonetheless, a number of in-situ recovery methods have been developed to extract heavy oil and bitumen from deep reservoirs. Once produced, bitumen is transferred to upgraders converting low quality oil to synthetic crude oil. However, in the present context, heavy oil and bitumen exploitation process is not just high-energy and water intensive, but also it has significant environmental footprints as it produces significant amount of gaseous emissions and wastewater. In addition, the level of contaminants in bitumen requires special equipment, and has also environmental repercussions. Recently, nanotechnology has emerged as an alternative technology for in-situ heavy oil upgrading and recovery enhancement. Nanoparticle catalysts (nanocatalysts) are one of the important examples on nanotechnology applications. Nanocatalysts portray unique catalytic and sorption properties due to their exceptionally high surface area-to-volume ratio and active surface sites. In-situ catalytic conversion or upgrading of heavy oil with the aid of multi-metallic nanocatalysts is a promising cost effective and environmentally friendly technology for production of high quality oils that meet pipeline and refinery specifications. Further, nanoparticles could be employed as inhibitors for preventing or delaying asphaltene precipitation and subsequently enhance oil recovery. Nevertheless, as with any new technologies, there are a number of challenges facing the employment of nanoparticles for in-situ catalytic upgrading and recovery enhancement. The main goal of this article is to provide an overview of nanoparticle technology usage for enhancing the in-situ catalytic upgrading and recovery processes of crude oil. Furthermore, the article sheds lights on the advantages of employment of nanoparticles in heavy oil industry and addresses some of the limitations and challenges facing this new technology.

In this study, nC7-asphaltenes adsorption and subsequent catalytic oxidation over three transition metal oxide nanoparticles, namely TiO 2 , ZrO 2 , and CeO 2 were investigated. nC7-asphaltenes studied were obtained from Athabasca vacuum residue using n-heptane. The adsorption equilibrium data of nC7-asphaltenes, dissolved in toluene, fitted very well to the Langmuir adsorption isotherm model. The adsorption behavior of nC7-asphaltenes appeared to change with the type of adsorbent used. It was found that nC7-asphaltenes adsorption at 25 °C is metal oxide specific and the adsorption capacities ranked in the following order: CeO 2 > ZrO 2 > TiO 2 . On the other hand the adsorption affinity followed the following order: CeO 2 > TiO 2 > ZrO 2 . Theoretical calculations of the interaction between the Quinolin-65 (Q-65) (a compound used as a model asphaltene molecule) and some of the metal oxides surfaces were carried out to get more insight into its adsorption behavior. Adsorption energies of Q-65 on the surfaces indicated that there are different adsorption sites on each metal oxide. To confirm the catalytic activity of the selected oxide nanoparticles, the nC7-asphaltenes adsorbed onto the transition metal oxide nanoparticles were subjected to oxidation up to 700 °C in a thermogravimetric analyzer. All tested nanoparticles showed high catalytic activity for post adsorption oxidation. The oxidation kinetics was studied using the Ozawa–Flyn–Wall (OFW) corrected method. The mechanism function of the nC7-asphaltenes oxidation is strongly dependent on the type of nanoparticles. The kinetic oxidation parameters and the transition state thermodynamic functions for the oxidation process of nC7-asphaltenes in the presence and absence of nanoparticles, to the best of our knowledge, are reported for the first time. Among the selected transition metal oxide nanoparticles, CeO 2 appears to have the lowest values of effective activation energy and change in Gibbs free energy of activation (Δ G ‡ ).

Oil spills on fresh water can cause serious environmental and economic impacts onshore activities affecting those who exploit freshwater resources and grassland. Alumina nanoparticles functionalized with vacuum residue (VR) were used as a low-cost and high hydrophobic nanosorbents. The nanomaterial resulting showed high adsorption affinity and capacity of oil from oil-in-freshwater emulsion. The effects of the following variables on oil removal were investigated, namely: contact times, solution pH, initial oil concentrations, temperature, VR loadings and salinity. Kinetic studies showed that adsorption was fast and equilibrium was achieved in less than 30 min. The amount adsorbed of oil was higher for neutral system compared to acidic or basic medium. Increasing the VR loading on nanoparticle surface favored the adsorption. Results of this study showed that oil removal for all systems evaluated had better performance at pH value of 7 using nano-alumina functionalized with 4 wt% VR. Adsorption equilibrium and kinetics were evaluated using the Polanyi theory-based Dubinin–Ashtakhov (DA) model, and pseudo-first and pseudo-second order-models, respectively.

A recent paper by Abu Tarboush and Husein [1] discusses the catalytic activity of NiO nanoparticles obtained from different precursors/sources and questions the catalytic activity of commercial NiO nanoparticles reported previously [2] , [3] , [4] . In this communication we would like to reiterate the salient features of our work [2] , [3] , [4] that have been overlooked in the article of reference [1] . Also we point out some misinterpretation of TG/DTA data and possible flaws in experimental procedure described [1] . Based on the TG/DTA data provided [1] we have found that in situ prepared NiO species are catalytically less active than the commercially available NiO nanoparticles under discussion. Few recommendations are suggested that may enable the authors to study in depth the catalytic role of NiO nanoparticles for post-adsorption asphaltenes oxidation.

a b s t r a c t Thermogravimetry analyses have been employed to study the catalytic effect of different metal oxide nanoparticles on the thermo-oxidative decomposition of asphaltenes at isothermal conditions. Three metal oxide nanoparticles were considered in this study, namely: NiO, Co3O4 and Fe3O4. Results showed that the presence of nanoparticles decreased the activation energy of asphaltenes oxidation and enhanced the reaction rate. It appears that the thermo-oxidative reaction is metal oxide specific. The obtained kinetic data showed that NiO has the highest reaction rate followed by Co3O4 and then Fe3O4, which suggests a change in the reaction mechanism.

The presence of water in coal presents a technological challenge for its industrial use in energetic processes. Water tends to negatively affect the coal quality and its net heating value (NHV), in addition to affecting its transportation costs. Therefore, this study aims to investigate the effects of glycerol and temperature on water adsorption onto systematically modified coals. A Colombian bituminous coal sample was used as support for being modified with glycerol. The virgin coal and modified coal were characterized by nitrogen adsorption at 77 K (SBET), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, elemental analysis (C-H-N elemental) and thermogravimetric analysis (TGA). The results showed that the water uptake decreased as the amount of glycerol on the coal surface increased. The optimum concentration of 8 wt% of glycerol impregnated on the coal minimized water adsorption. Over a range of water activity evaluations, this amount of glycerol (C8) reduced water adsorption by approximately 60% compared with non-impregnated coal (C0). As expected, water uptake decreased with increasing temperature. These results are reflected in the NHV with an increase of 17% for the C8 sample compared with the other samples evaluated. The Talu and Meunier model was used to fit the experimental adsorption isotherms, and the mean square root error (MSRE%) was lower than 10%. The isosteric heat of sorption (IHS) for coal tends to decrease as the amount of adsorbed water increases. In addition, the value of IHS decreases as the concentration of glycerol increases due to the blocking of polar adsorption sites present on the coal surface, which are the main regions of low uptake of adsorbed water. Additionally, the Gibbs free energy was found to have negative values, which corroborates the spontaneous adsorption process.

Because of its unique properties, such as specific functionality and large specific surface area, iron oxide nanoadsorbents had showed potential for energy and environmental applications. This work investigated the adsorptive removal of different metal ions from wastewater by superparamagnetic iron oxide nanoadsorbents (Fe3O4). Batch-adsorption technique was employed to assess the kinetic behaviour and adsorption equilibrium of cadmium, cobalt and nickel. Accordingly, the effect of the following variables on the adsorption reaction was tested, namely: solution pH, contact time and temperature. Metal ion adsorption was found to be highly pH dependent with a maximum uptake achieved around pH 5.5. Kinetic studies showed that adsorption was fast and equilibrium was achieved in less than 60 min. The external mass transfer kinetic model was applied to the experimental results and provided reasonable overall volumetric mass transfer coefficients. Adsorption isotherms were determined and appropriately described by the Freundlich and Langmuir models, with a better fit to the Freundlich model. The amount of metal ion adsorbed increased as the temperature increased, suggesting an endothermic adsorption process. The thermodynamics studies indicated that the adsorption process was spontaneous and endothermic in nature. © 2011 Canadian Society for Chemical Engineering

In this study asphaltenes – waste hydrocarbons and problematic constituent present in heavy oil – have been investigated for its oxidation onto different types of nanoparticles, namely NiO, Co 3 O 4 and Fe 3 O 4 . All nanoparticles tested showed high adsorption affinity and catalytic activity for asphaltene adsorption and oxidation in the following order NiO > Co 3 O 4 > Fe 3 O 4 . The oxidation temperature of asphaltenes decreased by 140, 136 and 100 °C with respect to non-catalytic oxidation in the presence of NiO, Co 3 O 4 , and Fe 3 O 4 nanoparticles, respectively. A correlation appears to exist between the adsorption affinity and the catalytic activity, the higher the affinity the greater the catalytic activity.

A potentially-economic three-fold strategy, to use solid olive wastes in water purification, is presented. Firstly, oil remaining in solid waste (higher than 5% of waste) was recovered by the Soxhlet extraction technique, which can be useful for the soap industry. Secondly, the remaining solid was processed to yield relatively high-surface area active carbon (AC). Thirdly, the resulting carbon was employed to reversibly adsorb chromate ions from water, aiming to establish a water purification process with reusable AC. The technique used here enabled oil recovery together with the production of a clean solid, suitable for making AC. This process also has the advantage of low production cost.

Atactic polystyrene (PS) was used to study the effect of flow field (shear and/or elongational) on the intercalation of polymer/clay nanocomposites (PNC). Three grades of (PS), with different molecular weights, were compounded with an ammonium-modified montmorillonite (Cloisite 10A) in a twin-screw extruder (TSE). The compounds were subsequently fed to a single screw extruder, fitted with one of three specially designed torpedo-attachments. The attachments were designed to provide combinations of different levels of shear and elongational deformations. The resins, TSE compounds, and final PNC’s were characterized for the degree of intercalation, degradation, rheological behavior, and mechanical properties. The data showed that the thermal decomposition of the quaternary ammonium intercalant caused severe damage to both PNC components: a collapse of the organoclay interlayer spacing, and the thermo-oxidative degradation of PS. In spite of these detrimental effects, the attachment employing combined elongational and shear flow resulted in generally larger gallery spacing and more improvement of the mechanical properties than the other two attachments.

Formation water from oilfields is one of the major environmental issues related to the oil industry. This research investigated oil adsorption onto nanoparticles of hydrophobic alumina and alumina nanoparticles functionalized with a petroleum vacuum residue (VR) at 2 and 4 wt% to reduce the amount of oil in oil–saltwater emulsions at different pH values (5, 7 and 9). The initial concentration of crude oil in water ranged from 100 to 500 mg/L. The change in oil concentration after adsorption was determined using a UV–vis spectrophotometer. The results indicated that all of the systems performed more effectively at a pH of 7 and using Al/4VR material. The oil adsorption was higher for neutral and acid systems compared with basic ones, and it was improved by increasing the amount of VR on the surface of the alumina. Additionally, the amount of NaCl adsorbed onto nanoparticles was estimated for different mixtures. The adsorption equilibrium and kinetics were evaluated using the Dubinin–Astakhov model, the Brunauer−Emmet−Teller model, and pseudo-first- and pseudo-second-order models, with a better fitting to the Brunauer−Emmet−Teller model and pseudo-second-order model.

This study investigates the effect of surface acidity and basicity of aluminas on asphaltene adsorption followed by air oxidation. Equilibrium batch adsorption experiments were conducted at 25 C with solutions of asphaltenes in toluene at concentrations ranging from 100 to 3000 g/L using three conventional alumina adsorbents with different surface acidity. Data were found to better fit to the Freundlich isotherm model showing a multilayer adsorption. Results showed that asphaltene adsorption is strongly affected by the surface acidity, and the adsorption capacities of asphaltenes onto the three aluminas followed the order acidic > basic and neutral. Asphaltenes adsorbed over aluminas were subjected to oxidation in air up to 600 C in a thermogravimetric analyzer to study the catalytic effect of aluminas with different surface acidity. A correlation was found between Freundlich affinity constant (1/n) and the catalytic activity. Basic alumina that has the lowest 1/n value, depicting strongest interactions, has the highest catalytic activity, followed by neutral and acidic aluminas, respectively.

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.

Ultradispersed metal oxide nanoparticles have applications as heterogeneous catalysts for organic reactions. Their catalytic activity depends primarily on their surface area, which in turn, is dictated by their size, colloidal concentration and stability. This work presents a microemulsion approach for in situ preparation of ultradispersed copper oxide nanoparticles and discusses the effect of different microemulsion variables on their stability and highest possible time-invariant colloidal concentration (nanoparticle uptake). In addition, a model which describes the effect of the relevant variables on the nanoparticle uptake is evaluated. The preparation technique involved solubilizing CuCl 2 in single microemulsions followed by direct addition of NaOH. Upon addition of NaOH, copper hydroxide nanoparticles stabilized in the water pools formed in addition to a bulk copper hydroxide precipitate at the bottom. The copper hydroxide nanoparticles transformed with time into copper oxide. After reaching a time-independent concentration, mixing had limited effect on the nanoparticle uptake and particle size. Particle size increased with increasing the surfactant concentration, concentration of the precursor salt, and water to surfactant mol ratio; while the nanoparticle uptake increased linearly with the surfactant concentration, displayed an optimum with R and a power function with the concentration of the precursor salt. Surface areas per gram of nanoparticles were much higher than literature values. Even though lower area per gram of nanoparticles was obtained at higher uptake, higher surface area per unit volume of the reverse micellar system was attained. A model based on water uptake by Wisor type II microemulsions, and previously used to describe iron oxide nanoparticle uptake by the same microemulsions, agreed well with the experimental results.