Membrane surface modification and functionalization

[No abstract available]Scopu

Polydopamine functionalized graphene oxide as membrane nanofiller: Spectral and structural studies

High-degree functionalization of graphene oxide (GO) nanoparticles (NPs) using polydopamine (PDA) was conducted to produce polydopamine functionalized graphene oxide nanoparticles (GO-PDA NPs). Aiming to explore their potential use as nanofiller in membrane separation processes, the spectral and structural properties of GO-PDA NPs were comprehensively analyzed. GO NPs were first prepared by the oxidation of graphite via a modified Hummers method. The obtained GO NPs were then functionalized with PDA using a GO:PDA ratio of 1:2 to obtain highly aminated GO NPs. The structural change was evaluated using XRD, FTIR-UATR, Raman spectroscopy, SEM and TEM. Several bands have emerged in the FTIR spectra of GO-PDA attributed to the amine groups of PDA confirming the high functionalization degree of GO NPs. Raman spectra and XRD patterns showed different crystalline structures and defects and higher interlayer spacing of GO-PDA. The change in elemental compositions was confirmed by XPS and CHNSO elemental analysis and showed an emerging N 1s core-level in the GO-PDA survey spectra corresponding to the amine groups of PDA. GO-PDA NPs showed better dispersibility in polar and nonpolar solvents expanding their potential utilization for different purposes. Furthermore, GO and GO-PDA-coated membranes were prepared via pressure-assisted self-assembly technique (PAS) using low concentrations of NPs (1 wt. %). Contact angle measurements showed excellent hydrophilic properties of GO-PDA with an average contact angle of (27.8°).Scopu

A review of recent advances in water-gas shift catalysis for hydrogen production

The water-gas shift reaction (WGSR) is an intermediate reaction in hydrocarbon reforming processes, considered one of the most important reactions for hydrogen production. Here, water and carbon monoxide molecules react to generate hydrogen and carbon dioxide. From the thermodynamics aspect, pressure does not have an impact, whereas low-temperature conditions are suitable for high hydrogen selectivity because of the exothermic nature of the WGSR reaction. The performance of this reaction can be greatly enhanced in the presence of suitable catalysts. The WGSR has been widely studied due do the industrial significance resulting in a good volume of open literature on reactor design and catalyst development. A number of review articles are also available on the fundamental aspects of the reaction, including thermodynamic analysis, reaction condition optimization, catalyst design, and deactivation studies. Over the past few decades, there has been an exceptional development of the catalyst characterization techniques such as near-ambient x-ray photoelectron spectroscopy (NA-XPS) and in situ transmission electron microscopy (in situ TEM), providing atomic level information in presence of gases at elevated temperatures. These tools have been crucial in providing nanoscale structural details and the dynamic changes during reaction conditions, which were not available before. The present review is an attempt to gather the recent progress, particularly in the past decade, on the catalysts for low-temperature WGSR and their structural properties, leading to new insights that can be used in the future for effective catalyst design. For the ease of reading, the article is divided into subsections based on metals (noble and transition metal), oxide supports, and carbon-based supports. It also aims at providing a brief overview of the reaction conditions by including a table of catalysts with synthesis methods, reaction conditions, and key observations for a quick reference. Based on our study of literature on noble metal catalysts, atomic Pt substituted Mn3O4 shows almost full CO conversion at 260 °C itself with zero methane formation. In the case of transition metals group, the inclusion of Cu in catalytic system seems to influence the CO conversion significantly, and in some cases, with CO conversion improvement by 65% at 280 °C. Moreover, mesoporous ceria as a catalyst support shows great potential with reports of full CO conversion at a low temperature of 175 °C.Scopu

Protecting environment and assuring efficient energy transfer using ionic liquids

Gas hydrates are ice-like crystalline compounds that are formed when small gas molecules get trapped within the water molecules under high pressure and low-temperature conditions in oil and gas transmission lines. The formation of these hydrates is a major threat to oil and gas industry as they have a tendency to agglomerate and completely block the oil and gas transmission lines, which may lead to an explosion or cause unwanted operations shut down. Therefore, annually industry spends around 1 billion US dollars on hydrate prevention procedures which includes extensive use of chemical inhibitors. These chemical inhibitors are generally classified as thermodynamic hydrate inhibitors (THI) and kinetic hydrate inhibitors (KHI). The thermodynamic hydrate inhibitors function by shifting hydrate dissociation temperature to lower values and kinetic hydrate inhibitors function by delaying the hydrate formation time. The commercial THI like Methanol and Mono-ethylene glycol (MEG) perform well, but these inhibitors are required in large quantities (> 30 wt%) and cannot be easily disposed of into the environment. Therefore, there is a strong industrial need to design inhibitors that are environmentally friendly and are required in low dosage. Ionic liquids (ILs) well known as ionic fluids are a type of organic salts that have low melting points and tendency to stay in a liquid form at low or ambient temperature. Ionic liquids are extensively being used in different chemical processes due to their negligible vapor pressure and low viscosity. Recently, ionic liquid has been recognized as the dual functional inhibitors as they have the tendency to perform as kinetic hydrate inhibitor and thermodynamic hydrate inhibitor simultaneously. In this experimental-based work, the thermodynamic inhibition (TI) and kinetic inhibition (KI) effect of ionic liquids (ILs) 1-Methyl-1-Propyl-pyrrolidinium Chloride [PM-Py][Cl] and 1-Methyl-1-Propyl-pyrrolidinium Triflate [PM-Py][Triflate] have been investigated on a methane-rich gas mixture at different concentrations (1-5 wt%) and pressure ranges (40-120 bars). The effect of the addition of synergists with ionic liquids has been also studied and the experimental results have been compared with the commercial thermodynamic inhibitor methanol and literature data. All the experimental work has been conducted using PSL system tecknik rocking cell assembly (RC-5). The ionic liquid [PMPy][Cl] was found to be more effective than the IL [PMPy][Triflate].These experimental results, clearly show that the selected ionic liquids have a tendency to act as thermodynamic and kinetic inhibitors both simultaneously. In order to improve the kinetic inhibition effectiveness of the ionic liquids, the synergist polyethylene oxide (PEO) was added in equal ratio with the ionic liquids [PMPy][Triflate] and [PMPy][Cl]. The addition of PEO helped to enhance the kinetic inhibition effectiveness of these inhibitors significantly and delayed the hydrate induction time by 6 to 14 hours at the pressure range of 40-120 bars. A delay of 6 to 14 hours in hydrate induction time is highly beneficial for process operators as it allows them to take necessary action to avoid process disruptions as a result of hydrate formation. Acknowledgement This work was made possible by NPRP grant # 6-330-2-140 and GSRA # 2-1-0603-14012 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.qscienc

Humidification-Dehumidification (HDH) Desalination and Other Volume Reduction Techniques for Produced Water Treatment

Volume reduction has been suggested as a novel method to tackle the various challenges associated with produced water. The present solution offers an economical and environmentally friendly solution to treat a large bulk of produced water that may overwhelm conventional water treatment methods. The current study provides a review of the various volume reduction technologies including freeze concentration, reverse osmosis, and humidification and dehumidification desalination systems. Focus is concentrated on the general HDH technologies in addition to its integration with refrigeration cycles for conditioned air production, and the power cycles for power generation. The GOR, freshwater yield, and efficiencies of the integrated HDH systems were re-viewed. Lastly, innovation in the HDH desalination technology is discussed with emphasis on its incorporation with the MVC process.Scopu

A better understanding of seawater reverse osmosis brine: Characterizations, uses, and energy requirements

Before investing in any optimizing technology for the recovery and reuse of brine resources, it is of importance to study the full physicochemical characteristics of the brine. In the current study, the physicochemical characteristics of Qatari seawater reverse osmosis (SWRO) brine were fully investigated. The current study intends to lead to a better understanding of the nature of SWRO brine given the economic significance for the country that can be benefited from recycling and reusing various components. The characterization includes physical and chemical composition, as well as mineralogical and morphological investigation. The chemical analysis revealed that the seawater reverse osmosis brine contains various valuable elements and metals such as Ca (77120 mg/L), Na (343500 mg/L), Li (238800 mg/L), Ba (3.3 mg/L), Cs (3.4 mg/L), Fe (30.5 mg/L) and Mg (238800 mg/L). The pH of the brine was 8, while the electrical conductivity and salinity were 90.56 mS/cm and 61.4 ppt, respectively. The scanning electron microscopy-energy-dispersive and energy-dispersive X-ray revealed the placement of various valuable metals on the salt surface. X-ray diffraction showed eight XRD peaks. Interestingly, one peak at 2? of 31.7� is significantly more intense than the other seven peaks obtained, while all the eight peaks are extremely narrow. The Fourier-transform infrared spectroscopy analysis of the brine sample showed the presence of various functional groups. The narrow and intense peak around 1408 cm?1 confirms the presence of the S[dbnd]O bond in the brine sample, which could correspond to the presence of sulfonyl chlorides or sulfates as indicated by the ICP-OES results. Furthermore, a comparison between the energy requirements for the widely used seawater desalination technologies was presented. Additionally, this study showed the economical and environmental advantages and potential for recovering valuable metals from seawater reverse osmosis brines.Scopu

Sustainable innovation in membrane technologies for produced water treatment: Challenges and limitations

Discharged water from the oil and gas fields is a common type of wastewater called produced water (PW). It consists of different combinations of salinities, oils, and mineral deposits. Growing industrial demand, accelerated urbanization, and rapid population growth are putting enormous strain on the world?s water supply. Based on sustainable freshwater supplies, North Africa, the Middle East, and South Asia confront the ultimate water shortages threat. Proper implementation of innovative membrane technologies in wastewater treatment is considered a solution towards tackling water insecurity and sustainability. Different types of innovative membrane technologies used for produced water treatment were considered in this work. A framework of innovative membrane technology was studied for industrial wastewater with direct contribution to the environmental and economical sustainability factors, taking into consideration grand challenges and limitations in energy costs and environmental constraints. Treated produced water can be utilized in irrigation providing many benefits only if the desalination sector is mature and fully developed.Scopu

Biological-Based Produced Water Treatment Using Microalgae: Challenges and Efficiency

Produced water (PW) is the most significant waste stream generated in the oil and gas industries. The generated PW has the potential to be a useful water source rather than waste. While a variety of technologies can be used for the treatment of PW for reuse, biological-based technologies are an effective and sustainable remediation method. Specifically, microalgae, which are a costeffective and sustainable process that use nutrients to eliminate organic pollutants from PW during the bioremediation process. In these treatment processes, microalgae grow in PW free of charge, eliminate pollutants, and generate clean water that can be recycled and reused. This helps to reduce CO2 levels in the atmosphere while simultaneously producing biofuels, other useful chemicals, and added-value products. As such, this review focuses on PW generation in the oil and gas industry, PW characteristics, and examines the available technologies that can be used for PW remediation, with specific attention to algal-based technologies. In addition, the various aspects of algae growth and cultivation in PW, the effect of growth conditions, water quality parameters, and the corresponding treatment performance are presented. Lastly, this review emphasizes the bioremediation of PW using algae and highlights how to harvest algae that can be processed to generate biofuels for added-value products as a sustainable approach.Scopu

Development of Green Inhibitors to Prevent Hydrates Formation, Protect Environment and Reduce Energy Cost in Oil and Gas Industry

Gas hydrates are identified as ice-liked solid, crystalline compounds having polyhedral water cavities, where gas molecules get trapped during operation under high pressure and low temperature condition. These hydrates have a tendency to completely block the pipelines and can cause major operations shutdown, leading to large economic losses and causing high safety risk in transmission pipelines. Thus, annually the oil and gas sector spends over 100 million US $ on purchase of chemical inhibitors that can help to prevent hydrates formation in subsea lines. These inhibitors are classified into two separate categories, the thermodynamic and kinetic inhibitors. The thermodynamic inhibitors act by shifting the hydrates formation temperature and the kinetic inhibitors act by shifting the hydrates formation time. Currently, the thermodynamic inhibitors like Methanol and Methylene ethylene glycol (MEG) are mainly used in industry. These inhibitors are highly flammable and cannot be disposed of easily into the environment. They are required in bulk quantities (>30 wt%) and separate facility is needed for their storage and treatment process. This increases the overall energy cost and leads to major environmental disposal issue. Therefore, there is a high demand for inhibitors that are environmentally friendly and cost effective in oil and gas sector. Ionic liquids (ILs) are salt like compounds that have received attention due to their environmentally friendly, recyclable and non-flammable nature. These ILs have potential to prevent hydrate formation and they can act as both thermodynamic and kinetic inhibitors simultaneously. In this work, the Pyrrolidinium based ILs have been tested as gas hydrate inhibitors and synergistic compounds (Syn) are added with these ILs to improve their overall effectiveness. For the first time, the thermodynamic and kinetic study on ILs has been conducted using high dosage mixture of ILs + Syn on methane rich gas mixture to check their effectiveness in preventing gas hydrates formation. All the experiments are performed using a high pressure rocking cell assembly supplied by PSL Systemtechnik GmBH, at different pressures ranging from (40 to 120) bars. According to the tests results, we have evaluated that the mixtures were able to prevent hydrates formation by providing a temperature shift of up to 2.2°C at low pressures and by delaying hydrates formation time by (6 to 14) hours. These results confirm the dual inhibition behaviour of these mixtures, as they were able to shift hydrates formation temperature and delay hydrates formation time simultaneously. The results were also compared with widely known industrial inhibitor methanol and only a difference of 0.5°C was observed. Thus, this research provides an innovative approach towards development of environmentally friendly inhibitors and to reduce energy cost in the oil and gas industry.qscienc