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Recently, the application of nanoparticles for enhancing oil recovery (EOR) in carbonate reservoirs has received great attention from various researchers across the oil and gas industry. In contras...

A large number of researchers have endeavored to delineate the effects of injecting brine with a low ionic strength in oil reservoirs in the past decade. However, we still cannot conclude the overr...

Effects of pressure on thermo-oxidative decomposition of different sources of n-C7 asphaltenes were investigated at high pressure using a thermogravimetric analyzer under an air atmosphere. The n-C...

Using Quinolin-65 (Q-65) and Violantrone (V-79) as model molecules for polar heavy hydrocarbons and resins, the nanosize effects of NiO nanoparticles on the competitive molecular adsorption on nano...

This work is a first attempt to understand the mechanism of metformin thermal decomposition under inert conditions. Thermal gravimetric analysis coupled with mass spectrometry was used to probe the thermal degradation reactions. Density functional theory and second-order perturbation (MP2) theoretical calculations were used to construct a reaction mechanism for metformin decomposition. It was evident that the reactions are initiated via formation of methyl radicals, and ammonia via 1.3-H shift, followed by a series of different secondary reaction pathways. The formation of cyanamide, dimethylamine and HCN were among the main secondary products. The proposed mechanism is important for future treatment of wastewater containing metformin and similar drugs formulations, and their possible conversion to useful commodities.

Oil sands exploitation in Alberta relies on water-intensive processes that result in large amounts of oil sand process-affected water (OSPW). Tailings ponds are used to store OSPW in accordance with government regulations. One of the main challenges of these tailings ponds is the settling of fine particles which, without treatment, would remain suspended for decades. This study introduces a novel application for the oxy-cracking technique to enhance fine particle settling through simultaneous oxidation and cracking reactions: residual bitumen and hydrocarbons are cracked and solubilized in the liquid phase, freeing the fine particles to agglomerate and settle faster. The pathway for this process is determined by the kinetics parameters, and it releases minimal CO2. A full lumped kinetics model study is presented to describe the oxy-cracking reaction. Settling enhancement and dewaterability were studied using the initial settling rate (ISR) and capillary suction time (CST) methods. After oxy-cracking, the ...

Nanoparticles (NPs) have recently gained great attention as effective agents for enhanced oil recovery (EOR) applications, especially at ambient temperatures. Nevertheless, harsh conditions are nee...

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.

Crude oil spills are of global concern because of their potential to cause massive water pollution and the destruction of aquatic life. The current technologies for oil spill cleanup only focus on impact mitigation and ignore crude oil recovery. There is therefore a need for an innovative technology that generates materials with crude oil recovery capabilities. Since manufactured materials have shown promising capabilities for recovering crude oil and treating water at the same time, this study examines and develops a strategy for manufacturing magnetic hexagonal boron nitride (h-BN) nanostructured composites—a high-performance material that can be used to both clean water and recover crude oil for further use after a crude oil spill. This manufacturing technique is unique as it consists of a single step and contemplates h-BN synthesis at 1300 K compared to 2275 K used previously. The material produced is capable of absorbing crude oil up to 53 times its own weight, employing only a magnetic field for the...

Foams in the oil and gas industry have been used as divergent fluids to attenuate the fluid channeling in high-permeability zones. Commonly, foams are generated using a surfactant solution in high-permeability reservoirs, which exhibit stability problems. Therefore, the main objective of this study is to stabilize the foams by the addition of modified silica nanoparticles, varying the surface acidity and polarity for natural gas flooding in tight gas-condensated reservoirs. Four types of modified silica-based nanoparticles with varying surface acidity and polarity (coated with vacuum residue) were synthesized and evaluated using surfactant adsorption. The basic nanoparticles exhibited a greater adsorption capacity of the surfactant, reaching an adsorbed amount of approximately 200 mg of surfactant per gram of nanoparticles, and Type I adsorption behavior. Foams were generated and evaluated based on their stability using two routes, namely, (1) with mechanical agitation and (2) methane flooding, to determi...

Pyrolysis and oxidation of asphaltene-born coke-like residue formed onto ex situ and in situ prepared NiO nanoparticles as initial steps toward developing advanced in situ combustion enhanced oil recovery (EOR) processes were studied. The in situ synthesized NiO nanoparticles in heavy oil matrix, containing coke-like residue, were characterized by X-ray diffraction, Brunauer–Emmett–Teller, field-emission scanning electron microscopy, and energy-dispersive X-ray mapping techniques. The pyrolysis and postpyrolysis oxidation of the coke residue were investigated by temperature-programmed pyrolysis (TPP) and temperature-programmed oxidation (TPO) methods, respectively. Oxidation kinetics of the coke residue was described by the Kissinger–Akahira–Sunose isoconversional method. The results showed a higher percentage of coke residue on the in situ prepared nanoparticles than the ex situ employed ones. Eventually, during the TPP of the coke residue, the amount of carbon oxides released per total amount of the cok...

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

The global production of residual feedstock has reached 150 million metric tons per annum and is expected to increase in the future due to the progressively increasing heavier nature of the crudes. Petroleum coke (petcoke), one of these residues, is a solid-rich carbon typically produced during the upgrading of heavy oil and delay coking of vacuum residue in the refinery. Finding an alternative technique to treat this massive amount of petcoke is highly needed as the conventional processes like gasification and combustion have limitations in terms of efficiency and environmental friendliness. In this study, an oxy-cracking technique, which is a combination of cracking and oxidation reactions, is conducted as an alternative approach for petcoke utilization. The reaction is conducted in a Parr reactor where petcoke particles are solubilized in an aqueous alkaline medium and partially oxidized under mild operating temperature and pressure. Several operating conditions on petcoke oxy-cracking were investigated, such as temperature, oxygen pressure, reaction time, particle size and mixing rate to optimize the solubility and selectivity of oxy-cracked products. The results showed that the temperature and the residence time are the two major important parameters that affect the reaction conversion and selectivity. This enabled us to propose a reaction pathway based on the radical mechanism to describe the kinetic behavior of petcoke. Reaction kinetics indicated that petcoke oxidation undergoes a parallel-consecutive reaction in which an oxidative decomposition took place in the first step producing different oxidized intermediates. The oxy-cracked petcoke was characterized by FTIR, XPS and NMR analyses. The oxy-cracked products were found to contain carboxylic, carbonyl, phenolic, and sulfonic functions. Moreover, the elemental analysis showed that most of the metals remained in the residue, suggesting that the proposed technique could be employed for petcoke demineralization.

Extracting Alberta’s bitumen by SAGD requires a growing supply of steam, which is mainly generated from recycled produced water (PW). Traditionally, a warm lime softener (WLS), followed by walnut shell filter (WSF) and weak acid cation exchange (WAC) units have been employed to minimize the concentrations of silica, TOC, and hardness from PW. In this study, we enhanced TOC and silica removal in a WSF unit by modifying the surface of the walnut shell media. The walnut shells were modified by anchoring low mass percentages (e.g.

The primary objective of this study is to investigate the effects of SiO2 nanoparticles on improving the rheological behavior and inhibition of the thermal degradation of hydrolyzed polyacrylamide (HPAM) solutions. The SiO2-HPAM interactions were evaluated through i) Polymer adsorption onto nanoparticles, ii) rheological studies, and iii) evaluation of thermal stability in presence or absence of oxygen. SiO2 nanoparticles and HPAM were characterized through thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS). The nanofluids were prepared by adding a fixed concentration of nanoparticles to an HPAM-containing aqueous solution. The adsorption isotherms of HPAM over the SiO2 nanoparticles were obtained in batch-mode experiments. Results of adsorption experiments showed that isotherms followed a Type III behavior. The adsorption isotherms were modeled using Langmuir, Freundlich and Solid-Liquid Equilibrium (SLE) model. The best fitting was obtained using the SLE model based on the root-mean-square error (RMSE%), which was lower than 9.5. Also, polymer desorption from the surface of nanoparticles was found to be negligible, and thus the sorption process can be considered irreversible under conditions evaluated. Rheological tests in the range of 25 to 70 °C showed a pervasive non-Newtonian behavior for all the SiO2-HPAM combinations tested. The Herschel-Bulkley and Carreau models were used to describe the rheological behavior of the prepared nanofluids with RMSE% values better than 0.3. The thermal stability of polymeric solutions in the absence and presence of nanoparticles was evaluated under inert and oxidative atmospheres at 70 °C for 14 days. It was observed that a lower degree of degradation resulted for polymeric solutions in the presence of nanoparticles and the absence of oxygen, indicating that SiO2 nanoparticles can inhibit HPAM degradation through adsorption, and subsequently improve its thermal stability.

In a previous study, the effect of the nanosize of NiO particles on its surface properties for the Quinolin-65 (Q-65) adsorption from toluene-based solution has been investigated and well established. In this work, the effect of nanosize of NiO particles on the catalytic thermo-oxidative decomposition of the adsorbed Q-65 was investigated using TGA/DTA and TGA-MS systems. Virgin Q-65 and Q-65 adsorbed on 5 nm sized NiO particles have been oxidized to the same conversion degree α = 0.3, to get the transitional product. FTIR and XPS have been used to characterize the transitional product. Kissinger-Akahira-Sunrise (KAS) isoconversional method was used to describe the oxidation mechanism and to confirm the validity of the catalytic effect of the different-sized NiO nanoparticles. Taken together, the kinetic triplets (i.e., the effective activation energy E α , the pre-exponential factor A α and the reaction function, f ( α )) are necessary specifications to examine and allow meaningful comparisons of the catalytic activity of the different-sized NiO nanocatalysts. The gas analysis TGA-MS system and the thermodynamic parameters suggested that the smaller the particle size is, the higher the catalytic activity, and the faster CO 2 formation. The critical NiO nanosize was observed to be between 15 and 30 nm, were the shape become flat and the atomic distribution are barely changed with further increasing of the size. NiO nanoparticles with size

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

Oxy-cracking is a combination of oxidation and cracking reactions for converting heavy hydrocarbons into commodity products with minimal emission of CO2. This reaction takes place in basic aqueous media, at mild operation temperatures (200–230 °C) and pressures (500–750 psi). In this study, the main goal is to understand the oxy-cracking mechanism, involving oxidation and cracking reactions, of solid hydrocarbons represented by the model molecule Quinolin-65 (Q-65). In the experimental part, the oxy-cracking reaction was performed in a Parr batch reactor operated at an optimized oxygen partial pressure of 750 psi and temperatures between 200 °C and 230 °C. The reaction products were characterized by FTIR spectroscopy, TOC analysis, GC, NMR spectroscopy, and XPS. We found that the main products are composed of organic carboxylic, phenolic, and carbonyl-containing compounds, with small amounts of inorganic carbon (IC). In the theoretical part of the study, a comprehensive computational modeling of Q-65 reactivity was performed using high-level quantum theoretical calculations. The reaction studies indicated the attack of the hydroxyl radical (OH˙) and hydroxide anion (OH−) on the Q-65 molecule. The theoretical study employed the density functional theory (DFT) and the second-order Moller–Plesset perturbation theory (MP2) to study the reaction mechanisms under the same experimental conditions. Both the theoretical and the experimental studies confirmed the complexity of the reaction kinetics. The reaction kinetic results suggested that the Q-65 oxy-cracking reaction went through a parallel-consecutive reaction in which oxidative decomposition took place in the first step producing different aromatic intermediates. These intermediates were oxy-cracked consecutively into different organic acids and a small amount of CO2 gas.

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.

The main objective of this study is to evaluate the effect of particle size and surface acidity of synthesized silica gel nanoparticles on the inhibition of formation damage caused by asphaltene precipitation/deposition. Silica gel nanoparticles were synthesized through the sol–gel method, and their characterization was performed via N2 physisorption at −196 °C, field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS) measurements, and NH3 temperature-programmed desorption (TPD). The size of the synthesized nanoparticles ranged from 11 to 240 nm. The ability of the nanoparticles to adsorb asphaltenes and to reduce asphaltene self-association was evaluated using batch-mode experiments. The kinetics of asphaltene aggregate growth in the presence and absence of nanoparticles were evaluated using DLS measurements in different Heptol solutions. The smallest nanoparticles (11 nm) had the highest adsorptive capacity for n-C7 asphaltenes among the nanoparticles studied. Therefore, these...

The primary objective of this study is to show the importance of the adsorption method used in obtaining the nanoparticle dosage for inhibiting/remediating asphaltene-related problems. In this work, two methods for determining the adsorption isotherms for different asphaltenes onto three different types of nanoparticles were evaluated. The adsorption equilibrium of n-C7 asphaltenes was determined using batch-mode adsorption experiments that were performed in two different ways: (i) by exposing a certain mass of nanoparticles in a fixed volume of liquid with a varying initial concentration of asphaltenes and (ii) by exposing a given amount of asphaltenes in a fixed volume of liquid while varying the dosage of nanoparticles. The results obtained using these two methods were sufficient to determine the type I and III adsorption isotherms, respectively. These differences in behavior in adsorption isotherms can be due complexity of the n-C7 asphaltenes, which are self-associative molecules that impact directly...

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.

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.

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.

The anti-diabetic agent metformin (MF) is one of the most prescribed pharmaceutical compound worldwide. It is not completely metabolized after administration where 52% is excreted in urine. Accordingly, it highly contributes in generating wastewater containing MF. This pollutant is not effectively removed by the conventional wastewater treatment methods. Therefore, an effective advanced treatment technique should be implemented for the removal of MF from wastewater. In this study, silica-alumina (SA) is used as an environmentally-safe and effective adsorbent for removing MF from aqueous solution by adsorption. Adsorption experiments were employed studying the effect of pH, contact time, and MF initial concentration to investigate both the removal efficiency of MF and the interaction mechanism. A set of characterization techniques, such as SEM, BET, FTIR, TPD-MS, and zeta potential were performed before and after adsorption experiments to confirm the role of structural morphology, surface area, porosity, surface acidity and charge in adsorption. The characterization analysis showed that SA has BET surface area of 470 m2/g. From the total BET surface area, the microporous surface area was around 31% (147 m2/g), while the rest corresponds to the mesoporous surface area (323 m2/g). The batch adsorption results showed that high concentrations of MF were efficiently removed from water samples with a maximum uptake of 46 mg/L at optimal pH 9.0 (optimal pH). The mechanism responsible for adsorption was observed to be carried out via an electrostatic interaction between a negatively charged SA and a positively charged MF. TGA/DT analysis was conducted to assess the reusability of the spent SA by thermal regeneration at 673 K. The adsorbent was completely regenerated and maintained a 95% removal after 3 cycles without impacting the surface characteristics.

Using Quinolin-65 (Q-65) as a model-adsorbing compound for polar heavy hydrocarbons, the nanosize effect of NiO nanoparticles on the adsorption of Q-65 was investigated. Different-sized NiO nanoparticles with sizes between 5 and 80 nm were prepared by the controlled thermal dehydroxylation of Ni(OH)2. The properties of the nanoparticles were characterized using XRD, BET, FTIR, HRTEM and TGA. The effects of the nanosize on the textural properties, the shape and the morphology were studied. The adsorption of Q-65 molecules onto different-sized nanoparticles was tested in toluene-based solutions. On a normalized surface area basis, the number of Q-65 molecules adsorbed per nm(2) of the NiO surface was the highest for NiO nanoparticles of size 80 nm, while that for 5 nm sized NiO nanoparticles was the lowest. Excitingly, the adsorption capacity of other NiO sizes varied from loading suggesting different adsorption behavior, which exhibits the significance of textural properties during the adsorption of Q-65. Computational modeling of the interaction between the Q-65 molecule and the NiO nanoparticle surface was carried out to get more understanding of its adsorption behavior. A number of factors contributing to the enhanced adsorption capacity of nanoscale NiO were determined. These include surface reactivity, topology, morphology and textural properties.

The production of heavy and extra-heavy oil is challenging because of the rheological properties that crude oil presents due to its high asphaltene content. The upgrading and recovery processes of these unconventional oils are typically water and energy intensive, which makes such processes costly and environmentally unfriendly. Nanoparticle catalysts could be used to enhance the upgrading and recovery of heavy oil under both in situ and ex situ conditions. In this study, the effect of the Ni-Pd nanocatalysts supported on fumed silica nanoparticles on post-adsorption catalytic thermal cracking of n-C7 asphaltenes was investigated using a thermogravimetric analyzer coupled with FTIR. The performance of catalytic thermal cracking of n-C7 asphaltenes in the presence of NiO and PdO supported on fumed silica nanoparticles was better than on the fumed silica support alone. For a fixed amount of adsorbed n-C7 asphaltenes (0.2 mg/m2), bimetallic nanoparticles showed better catalytic behavior than monometallic nanoparticles, confirming their synergistic effects. The corrected Ozawa–Flynn–Wall equation (OFW) was used to estimate the effective activation energies of the catalytic process. The mechanism function, kinetic parameters, and transition state thermodynamic functions for the thermal cracking process of n-C7 asphaltenes in the presence and absence of nanoparticles are investigated.