Advances in the Study of Gas Hydrates by Dielectric Spectroscopy.

The influence of kinetic hydrate inhibitors on the process of natural gas hydrate nucleation was studied using the method of dielectric spectroscopy. The processes of gas hydrate formation and decomposition were monitored using the temperature dependence of the real component of the dielectric constant ε'(T). Analysis of the relaxation times τ and activation energy ΔE of the dielectric relaxation process revealed the inhibitor was involved in hydrogen bonding and the disruption of the local structures of water molecules.

Experimental study of non-oxidized and oxidized bitumen obtained from heavy oil.

Heavy oil and vacuum residue were used to obtain road bitumen BND 50/70 using two different methods of steam distillation at 323-362 °C and by oxidation, a method using packed column at temperature of 211-220 °C. The obtained residues using two methods steam distillation and oxidation are known as non-oxidized bitumen and oxidized bitumen, respectively. The products were evaluated using different standards including GOST 33133-2014, GOST 22245-90, and ASTM D5. The results showed that the yield of oxidized bitumen reached a maximal rate of 89.59% wt., while that of non-oxidized bitumen is 55% wt. The softening point of oxidized bitumen is 49-57 °C compared to non-oxidized bitumen (46-49 °C). Remarkably, the previous softening point and penetrability of 47-71 points of oxidized bitumen are consistent with norms to BND 50/70 bitumen, according standard. The non-oxidized bitumen has a relatively low softening point and a higher penetration value of 71-275, which refers to BND 200/300 bitumen. Comparatively, the use of a packed column is beneficial than the steam distillation, due to high capability of the nozzles to strengthens contact between feedstock and compressed air in the reaction zone and decreases the reaction time to 4.15 h.

Exploration of Sunflower Oil As a Renewable Biomass Source to Develop Scalable and Highly Effective Corrosion Inhibitors in a 15% HCl Medium at High Temperatures.

The feasibility study of utilizing sunflower oil as renewable biomass source to develop highly effective inhibitors for mild steel corrosion (MS) in the 15% HCl medium was done by weight loss, potentiodynamic polarization (PDP), dynamic electrochemical impedance spectroscopy (DEIS), and electrochemical impedance spectroscopy (EIS), supported with energy-dispersive X-ray (EDX), atomic force microscopy (AFM), and field-emission scanning electron microscope (FESEM) techniques. Moreover, a complementary theoretical investigation was carried out to clarify the inhibition mechanism of inhibitors by density functional theory (DFT), density functional based tight-binding (DFTB), and molecular dynamics (MD) simulation approaches. The obtained results confirm that sunflower-oil-based corrosion inhibitor (SFOCI) has a significant anticorrosion property toward the dissolution of MS in 15% HCl solution in the temperature range 20-80 °C. In addition, the results show that SFOCI could provide an inhibition efficiency of 98 and 93% at 60 and 80 °C, respectively. The inhibition mechanism of SFOCIs was mixed-type and their adsorption on the surface of MS was mainly chemisorption. The FESEM and EDX studies proved the presence of SFOCI molecules on the surface of MS. In addition, the adsorption energy of SFOCI indicated an intense interaction between the inhibitor and surface of Fe. The results of this study could open a new window for the design and development of scalable and effective eco-friendly vegetable-oil-based corrosion inhibitors for highly corrosive solutions at high temperatures.

Deep Insights into Heavy Oil Upgrading Using Supercritical Water by a Comprehensive Analysis of GC, GC-MS, NMR, and SEM-EDX with the Aid of EPR as a Complementary Technical Analysis.

Upgrading of heavy oil in supercritical water (SCW) was analyzed by a comprehensive analysis of GC, GC-MS, NMR, and SEM-EDX with the aid of electron paramagnetic resonance (EPR) as a complementary technical analysis. The significant changes in the physical properties and chemical compositions reveal the effectiveness of heavy oil upgrading by SCW. Especially, changes of intensities of conventional EPR signals from free radicals (FRs) and paramagnetic vanadyl complexes (VO2+) with SCW treatment were noticed, and they were explained, respectively, to understand sulfur removal mechanism (by FR intensity and environment destruction) and metal removal mechanism (by VO2+ complexes' transformation). For the first time, it was shown that electronic relaxation times extracted from the pulsed EPR measurements can serve as sensitive parameters of SCW treatment. The results confirm that EPR can be used as a complementary tool for analyzing heavy oil upgrading in SCW, even for the online monitoring of oilfield upgrading.

Sulfonated chitosan as green and high cloud point kinetic methane hydrate and corrosion inhibitor: Experimental and theoretical studies.

In this work sulfonated chitosan (SCS) was introduced as a promising green kinetic methane hydrate and corrosion inhibitor to overcome the incompatibility problem between inhibitors. Evaluation of hydrate inhibition performance of SCS with high-pressure autoclave and micro-differential scanning calorimeter revealed that hydrate formation was delayed 14.3 ±â€¯0.2 times and amount of hydrate formed was decreased to 30 % compared to water. The weight loss experiments showed that SCS provides corrosion inhibition efficiency of 95.6 ±â€¯0.1 at 5000 ppm concentration. SCS is able to increase polarization resistance and decrease corrosion current density according to electrochemical measurements. Study of surface morphology by SEM-EDX and profilometer showed that SCSs suppress corrosion rate and reduce the surface roughness of carbon steel. Quantum chemical study confirmed that the pendant groups caused by chitosan modification interact with carbon steel surface. The findings of this research can provide new opportunities to develop biodegradable materials as KHIs/CIs for flow assurance in oil and gas pipelines.

Sustained delivery of olanzapine from sunflower oil-based polyol-urethane nanoparticles synthesised through a cyclic carbonate ring-opening reaction.

The forefront horizon of biomedical investigations in recent decades is parcelling-up and delivery of drugs to achieve controlled/targeted release. In this regard, developing green-based delivery systems for a spatiotemporal controlling therapeutic agent have drawn a lot of attention. A facile route based on cyclic carbonate ring-opening reaction has been utilised to synthesise a bio-based polyol-containing urethane bond [polyol-urethane (POU)] as a nanoparticulate drug delivery system of olanzapine in order to enhance its bioavailability. After characterisation, the nanoparticles were also estimated for in vitro release, toxicity, and pharmacokinetic studies. As olanzapine has shown poor bioavailability and permeability in the brain, the sustained release of olanzapine from the designed carriers could enhance pharmacokinetic effectiveness. POU in the aqueous solution formed micelles with a hydrophobic core and embedded olanzapine under the influence of its hydrophobic nature. Drug release from the nanoparticles (90 ± 0.43 nm in diameter) indicated a specific pattern with initial burst release, and then a sustained release behaviour (82 ± 3% after 168 h), by the Higuchi-based release mechanism. Pharmacokinetics assessments of POU-olanzapine nanoparticles were carried in male Wistar rats through intravenous administration. The obtained results paved a way to introduce the POU as an efficient platform to enhance the bioavailability of olanzapine in therapeutic methods.

Waterborne Polyurethanes as a New and Promising Class of Kinetic Inhibitors for Methane Hydrate Formation.

A facile, new and promising technique based on waterborne polymers for designing and synthesizing kinetic hydrate inhibitors (KHIs) has been proposed to prevent methane hydrate formation. This topic is challenging subject in flow assurance problems in gas and oilfields. Proposed technique helps to get KHIs with required number and distance of hydrophilic and hydrophobic groups in molecule and good solubility in water. The performance of these new KHIs was investigated by high pressure micro-differential scanning calorimeter (HP-µDSC) and high-pressure autoclave cell. The results demonstrated the high performance of these inhibitors in delay the induction time (10-20 times) and reduce the hydrate growth rate (3 times). Also they did not increase hydrate dissociation temperature in comparison with pure water and show thermodynamic inhibition as well. Inhibition effect of synthesized polymers is improved with the increase of concentration significantly. Since this is the first report of the use of waterborne polymers as kinetic hydrate inhibitor, we expect that KHIs based on waterborne-based polymers can be a prospective option for preventing methane hydrate formation.

Design, characterization and in vitro evaluation of novel amphiphilic block sunflower oil-based polyol nanocarrier as a potential delivery system: Raloxifene-hydrochloride as a model.

Presently, modern pharmaceuticals, are almost exclusively derived from the arduous refining of petroleum whose supply is inherently unsustainable. In order to address this issue bio-based materials are increasingly being used for chemical synthesis, particularly in drug delivery systems. Biodegradable and biocompatible hyper-branched polyol (an alcohol containing three or more hydroxyl groups) was synthesized via a facile method through the ring-opening and thiol-ene click reactions at room temperature. Due to the bio-based content of the polyol backbone, the synthesized polyol had both excellent biodegradability and low cytotoxicity. Raloxifene hydrochloride, an oral selective estrogen receptor modulator, was used as a hydrophobic drug model to test the potential of polyol as a drug delivery system carrier. Polyol showed an amphiphilic character and could be prepared as a nanoparticle for the sustained delivery of raloxifene hydrochloride, a drug with poor bioavailability in aqueous solution. Raloxifene hydrochloride was readily encapsulated in the lipophilic core of polyol whose branched hydroxyls were on the external part of the prepared nanoparticles. The diameter of the nanoparticles was 94±0.43nm, their drug entrapment efficiency was 93±0.5% and they showed a sustained release profile (17±1.5% after 4weeks). The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay showed low toxicity towards human osteoblast MG-63 cells. Based on its good biodegradability and low cytotoxicity, polyol provides a bio-based source for the design new drug delivery systems.