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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.

Efficient removal of heavy metals from water and wastewater is a necessity for human and environmental well-being. Agricultural, domestic, and industrial waste discharges increase with the increase in the global population. Discharges are loaded with toxic metallic substances that inevitably reach water sources. Conventional treatment methods are in many cases inadequate in their removal efficiencies. Alternatively, recently developed advanced treatment approaches, such as nanotechnologies, offer advantages in water treatment. Nanotechnology brought about materials with high specific surface areas and adsorption capacities for the removal of undesirable heavy metals present in water. A detailed review of the use of nanotechnologies and nanomaterials for the removal of heavy metals from aqueous solutions is presented in this study. Limitations, research gaps, and suitability of nanotechnology in water treatment for the removal of heavy metals at a large scale are discussed, and relevant conclusions are accordingly deduced.

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...

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 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 (

In this study, H2 production via low-temperature catalytic steam gasification (CSG) of Athabasca visbroken vacuum residue adsorbed onto NiO–kaolin-based catalysts in a fixed-bed reactor was investigated. The CSG was carried out at 600, 650, and 700 °C. Two NiO–kaolin-based catalysts were used, containing either K2O or Cs2O along with BaO. XRD data showed the presence of a crystalline Ni3S2 phase in the spent catalyst only when K was used instead of Cs in the catalyst preparation. CSG experiments conducted for 100 h followed by regeneration confirmed that both catalysts are good candidates for H2 production via CSG of adsorbed heavy hydrocarbon feed in a fixed-bed reactor unit. However, the H2/CO2 ratio obtained during CSG is closer to 2 at all three temperatures studied for the 3NiO6K6Ba catalyst. Furthermore, the activation energies determined for the 3NiO6K6Ba and 3NiO6Cs6Ba catalysts for CSG of visbroken residue were 83 and 95 kJ/mol, respectively.

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.

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...

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.

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).

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 a previous study, we showed that Ni–Pd bimetallic nanocatalysts supported on fumed silica had better adsorption affinity and catalytic activity toward adsorption and post-adsorption decomposition of asphaltenes compared to the support without functionalization. In this study, the effect of oxide support types on the adsorption and subsequent steam gasification of adsorbed asphaltenes was studied over Ni–Pd bimetallic nanocatalysts supported on TiO 2 or γ-Al 2 O 3 nanoparticles. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and N 2 physisorption at 77 K were used to characterize the crystal size and surface area of NiO and/or PdO-supported-on-TiO 2 or γ-Al 2 O 3 nanoparticles, respectively. The type of support was shown to affect the adsorption affinity and catalytic activity of the particles; Ni–Pd/TiO 2 nanoparticles showed higher adsorption capacity and catalytic activity than Ni–Pd/γ-Al 2 O 3 , presumably due to different metal-support interaction and geometric and electronic effects on the surface. Bimetallic nanoparticles appeared to have better adsorption and catalytic behavior than monometallic nanoparticles regardless of the oxide support used, confirming their synergistic effect.

The precipitation and deposition of asphaltenes is a primary problem related to the processing, transportation, and production of oil. Flocculation of asphaltene aggregates is likely to occur during the production and processing of crude oil. Recently, it has been shown that nanotechnology in the form of nanoparticles is useful for the inhibition or prevention of asphaltene formation damage. Although it is well-known that the adsorption of asphaltenes on the nanoparticle surface would reduce the capacity of these asphaltic compounds to interact with each other, limited studies have been performed regarding the processes and the mechanisms associated with the effect of nanoparticles on the inhibition of the formation damage due to asphaltenes. To better understand this phenomenon from a mathematical approach, a population balance model (PBM) is proposed to describe the kinetics of asphaltene flocculation-fragmentation in the presence of nanoparticles. The model assumes that asphaltenes in the presence of a...

Asphaltenes may generate production loss in oil reservoirs, because of several factors related to the interaction between the asphaltene molecules, aggregates, and the reservoir rock. Consequently, this could alter the wettability of the rock surface, increase the viscosity of the crude oil, and reduce the permeability of the porous media. In a previous study, we have developed the solid–liquid equilibrium (SLE) model based on Chemical Theory to describe the adsorption behavior of asphaltenes onto porous and nonporous solid surfaces. However, the SLE model neglects the effect of pressure on the interactions of asphaltene–asphaltene and asphaltene–aggregate–solid surfaces of the reservoir rock primarily under reservoir conditions (RC). Thus, in this study, to account for the effect of pressure, a modification to the previously developed SLE equation is presented. In this study, a novel and original model—called the SLE-RC model of adsorption—has been proposed to describe the adsorption mechanism mainly und...

This study is a continuation of our previous works on the use of metal-based nanoparticles for the adsorption of asphaltenes and its subsequent catalytic thermal decomposition. In this study, we evaluated the effects of asphaltene aggregation on the adsorption process and the subsequent catalytic oxidation using fumed silica and nanoparticles of NiO and/or PdO supported on fumed silica. Adsorption isotherms were constructed through batch adsorption experiments at 25 °C by using mixtures of n-heptane and toluene in amounts of 0, 20% v/v n-heptane (Heptol 20), and 40% v/v n-heptane (Heptol 40) to obtain different aggregate sizes of asphaltenes. Subsequently, asphaltene oxidation in the presence and absence of the nanoparticles was carried out in a TGA/FTIR system to investigate the impact of adsorbed asphaltene aggregates on the catalytic activity of the selected nanoparticles. The adsorption isotherms were described by the solid–liquid equilibrium (SLE) model, and the catalytic behavior of the nanoparticle...

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.

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 ‡ ).

Asphaltenes exhibit an amphiphlic behavior and tend to form colloidal i-mers, because of their chemical structure. The formation of colloidal aggregates can generate formation damage for the precipitation and/or deposition of asphaltenes, because of the degree of self-association, altering the wettability of rock surface and significantly affect crude oil viscosity and specific gravity. This study aims at introducing a novel model for describing, at the macroscopic level, the adsorption equilibria of self-associating molecules such as asphaltenes in solution onto solid surfaces based on the “chemical theory”. The model describes the adsorption isotherms temperature-dependent using three parameters, namely, maximum amount adsorbed, constant of i-mer reactions, and Henry’s law constant. Furthermore, a temperature-independent model of five parameters, based on the modifications of the constants of reaction and Henry’s law using an Arrhenius-type equation was proposed for estimating the thermodynamics paramet...

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.

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.

High asphaltene content in heavy crude oil normally generates adverse rheological properties that affect the flow through the reservoir, preventing optimal hydrocarbon production. It has been demonstrated that using nanoparticles may improve the mobility of oil. Nanoparticles may be used as adsorbents and catalysts in the oil industry for in situ upgrading. The main objective of this study was to investigate the sorption kinetics and the thermodynamic equilibrium for asphaltene sorption onto nickel and/or palladium oxides supported on fumed silica that was nanoparticulated at different times, temperatures, and concentrations. After adsorption, thermally cracked asphaltenes from Colombian crude oil were investigated using catalytic oxidation. The asphaltenes adsorbed onto the selected nanoparticles were subjected to thermal decomposition up to 700 °C in a thermogravimetric analyzer. This study was realized using an experimental design with a measured simplex–centroid of the three components by varying the ...

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.

The deposition of asphaltenes is one of the most difficult problems to overcome in oil production and processing. The presence of asphaltenes in crude oil, and consequently, the adsorption and deposition of asphaltenes on the rock surfaces, affects the rock properties, such as porosity, permeability, and wettability. This study aims at analyzing the effect of the chemical nature of 12 types of nanoparticles on asphaltenes adsorption; hence, the delay or inhibition of deposition and precipitation of asphaltenes on porous media under flow conditions at reservoir pressure and temperature were investigated. The adsorption equilibrium of asphaltenes onto nanoparticles was effectively achieved within relatively short times (approximately 2 min), which indicates the promising nature of adsorbents for delaying the agglomeration and inhibiting the precipitation and deposition of asphaltenes. The adsorption equilibrium of asphaltenes for the nanoparticles was determined using a batch method in the range 150–2000 mg...

The deposition of asphaltenes is one of the most difficult problems to overcome in crude oil production and processing. The presence of asphaltenes in crude oil and, consequently, the adsorption and deposition of asphaltenes on rock surfaces, affects rock properties such as porosity, permeability, and wettability. In this study, a novel model for modeling and predicting adsorption isotherms of asphaltenes based on Polany’s modified theory is proposed. This approach enables prediction of adsorption isotherms at different temperatures (usually corresponding to reservoir temperatures), thereby improving our understanding of adsorption–equilibrium behavior at reservoir conditions, which should lead to reductions in experimental/analytical time and operation costs. The theoretical predictions of isotherms were validated successfully by determining the root-mean-square errors (RSM%) between data obtained from published literature and values predicted for asphaltenes and surfaces with differing chemical natures....

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.

Iron-oxide nanoadsorbents are attractive for wastewater treatment for two important reasons. First, nanoadsorbents can remove contaminants from wastewater rapidly. Second, iron oxide nanoadsorbents can be employed as catalysts for the decomposition of contaminants and thus eliminate sludge formation. This article investigates the use of iron-oxide nanoadsorbents to remove contaminants from wastewater. A later paper considers their use as catalysts for decomposition. In this study, goethite (a type of iron oxide) nanoparticles was employed for the removal of methylene blue from an aqueous solution, using a batch-adsorption technique. Effects of contact time, initial concentration of methylene blue, temperature, and solution pH on the adsorbed amount of methylene blue were investigated. Adsorption was rapid, as equilibrium was achieved within 20 minutes. An external mass transfer model fit adsorption kinetic results well and provided reasonable overall volumetric mass transfer coefficients. Increas...

Thermally cracked asphaltenes from Athabasca vacuum residue produced at four different process severities were investigated for adsorption and subsequent catalytic oxidation. Fe 3 O 4 nanoparticles were used for the removal of these four different thermally cracked asphaltenes from toluene solutions by a batch-adsorption technique followed by subsequent catalytic oxidation. Asphaltene adsorption kinetics and isotherms are presented. Further, the catalytic effect of nanoparticles on asphaltene oxidation has been addressed. Adsorption was rapid as equilibrium was achieved within 10 min. The equilibrium adsorption data fit well to the Langmuir model. It was found that the adsorption rate, affinity and capacity depend on the molecular weight (MW) of the asphaltenes. Adsorption rate and capacity were highest for the lower MW molecules while adsorption affinity was strongest for the larger MW molecules. In addition, in the absence of nanoparticles, the four thermally cracked asphaltenes oxidized differently. However, when adsorbed onto Fe 3 O 4 nanoparticles their oxidation behavior became similar, showing the enhanced catalytic effect of nanoparticles.

This study investigated the catalytic effect of NiO, Co3O4 and Fe3O4 nanoparticles toward asphaltene thermal decomposition (pyrolysis) under inert conditions. Asphaltene adsorbed onto the selected nanoparticles were subjected to thermal decomposition up to 800 °C in a thermogravimetric analyzer. The presence of nanoparticles caused a significant decrease in the asphaltene decomposition temperature and activation energy. Activation energies for the process were calculated using the Ozawa–Flynn–Wall method. All the selected metal oxide nanoparticles showed high catalytic activity toward asphaltene decomposition in the following order NiO > Co3O4 > Fe3O4. This study confirms that metal oxide nanoparticles can significantly enhance the thermal decomposition of heavy hydrocarbons, like asphaltenes.

In this study, the adsorption and catalytic oxidation of asphaltenes, problematic heavy hydrocarbons present in heavy oil, onto two aluminas with different particle sizes and comparable surface acidity were investigated. Equilibrium batch adsorption experiments were conducted at 25 °C with solutions of asphaltenes in toluene at concentrations ranging from 100 to 3000 mg/L. Adsorption data were fit to the Langmuir and Freundlich isotherm models. Nano-alumina fit better to the Langmuir model, while micro-alumina fit well to the Freundlich model. On a surface area basis, nano-alumina has higher adsorption capacity for asphaltenes than micro-alumina. Interestingly, micro-alumina has higher catalytic activity toward asphaltene oxidation than nano-alumina, at the same asphaltene loading, thus exhibiting the significance of textural properties during catalytic oxidation of asphaltenes that dominated over the effect of the particle size.

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.

Nanotechnology is a rapidly growing technology with considerable potential applications and benefits. Among the numerous applications of nanotechnology for energy and the environment, adsorption, oxidation, and gasification/cracking of asphaltenes, a problematic constituent present in heavy oil, on nanoparticle surfaces are one of the most recent examples. In this work, three different types of metal oxide nanoparticles, namely, Fe2O3, Co3O4, and NiO, were selected for asphaltene adsorption and catalytic steam gasification/cracking. Adsorption and gasification of asphaltenes were studied using thermogravimetric analysis. The nanoparticles were found to be very efficient for asphaltene adsorption and catalytic steam gasification/cracking. Asphaltene adsorption affinity on the surface of nanoparticles followed the following order: NiO > Co3O4 > Fe2O3. The catalytic steam gasification/cracking of asphaltenes in the presence of nanoparticles followed the same order as well. The calculated percent conversion a...

This study investigates the adsorption and oxidation of asphaltenes onto nanoparticles. Six different metal oxide nanoparticles were employed, namely, Fe3O4, Co3O4, TiO2, MgO, CaO, and NiO. Batch adsorption experiments were carried out at different initial asphaltene concentrations. Asphaltene adsorption was evaluated by measuring the asphaltene concentration using thermogravimetric analysis, and adsorption kinetics and isotherms were obtained. For all the six nanoparticles, the isotherm data fitted well to the Langmuir model. Results showed that asphaltene adsorption is metal-oxide-specific and the adsorption capacities of asphaltenes onto the oxides followed the order CaO > Co3O4 > Fe3O4 > MgO > NiO > TiO2. Furthermore, oxidation of asphaltene was investigated after adsorption onto NiO nanoparticles. The oxidation temperature of asphaltene decreased by ∼140 °C in the presence of nanoparticles, showing their catalytic effect. The activation energies calculated by the Coats−Redfern method for asphaltene o...

Asphaltene adsorption onto nanoparticles is an attractive subject for the heavy oil industry for two important reasons. First, nanoparticles would remove asphaltenes from the heavy oil rapidly and thus making the remaining fraction of oil transportable for conventional processing. Second, nanoparticles could be employed as catalysts for upgrading asphaltenes into light usable distillates. The first part has been investigated in this study, while the second part will be communicated shortly. In this study, the adsorption of asphaltenes from heavy oil model solutions onto colloidal nanoparticles of γ-Al2O3 is investigated. Batch adsorption experiments were carried out at different initial asphaltene concentrations and temperatures. The effects of the following variables on the amount of asphaltene adsorbed have been investigated, namely, contact time, initial concentration of asphaltenes, temperature, heptane/toluene ratio (H/T), coexisting molecules, and water content. Asphaltene adsorption kinetics and is...

The presence of dyestuffs in wastewater poses an environmental concern since these organic contaminants are toxic to aquatic and non-aquatic life. In addition, these contaminants are difficult to remove or biodegrade, which poses a challenge to the conventional wastewater treatment techniques. In this work, the adsorption of acid red dye 27 (AR27) onto γ-Fe2O3 nanoadsorbents was studied for the removal of red dye from aqueous solutions by the batch-adsorption technique. The experiments were carried out at different conditions of contact time, initial AR27 concentration, temperature, co-existing ions, and solution pH. It was found that the adsorption was a rapid process, and equilibrium was achieved in less than 4 minutes. The removal of AR27 decreased with the increase in solution pH and temperature. Furthermore, the addition of chloride and nitrate anions has no remarkable influence on AR27 removal efficiency. On the other hand, the effects of sulfate and bicarbonate anions on the removal of AR27 were si...

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.

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.