A critical review of the development and demulsification processes applied for oil recovery from oil in water emulsions

The formation of stable emulsions is a fundamental problem in oil industry that can result in a sequence of environmental and operational problems. Chemical demulsification is extensively applied for the recovery of oil from water as well as water from oil. This review introduces different chemical demulsifiers applied for the demulsification and recovery of oil from oil in water (O/W) emulsions. Main types of surfactants (anionic, cationic, nonionics and amphoteric) involved in the formation of emulsions and enhances their stability were discussed. Promising demulsifiers such as nanoparticle (NP), hyperbranched polymers, and ionic liquids (IL), which achieved high oil recovery rate, parameters influencing demulsification efficiency and demulsification mechanisms were explored. Lastly, improvements, challenges, and new changes being made to chemical demulsifiers were underlined. Functionalized magnetic nanoparticles and hyperbranched polymers were very effective in recovering oil from O/W emulsions with an efficiency >95%. Polymers with highly hydrophilic content and high molecular weight can achieve excellent oil recovery rates due to higher interfacial activity, higher dispersion, and presence of specific functional groups. Although ionic liquids could achieve oil recovery up to 90%, high cost limits their applications. NPs showed excellent oil recovery behavior at low concentrations and ambient temperature. Demulsification efficiency of NPs can be enhanced by functionalize with other components (e.g., polymers and surfactants), while service life can be extend by silica coating. Future challenges include scaling up the use of NPs in oil recovery process and highlighting contrasts between lab-scale and field-scale applications.This paper was made possible by the financial support provided through the internal collaborative grant number QUCG-CENG-21/22-3 funded by Qatar university . The statements made herein are solely the responsibility of the authors.Scopu

Evaluation of the efficiency of ionic liquids in the demulsification of oil-in-water emulsions

The production of oil in water emulsions (O/W-EMUL) is prevalent in the petroleum sector due to the presence of several stabilizers; however, O/W-EMUL is an unwanted phenomenon. Given that, this study evaluates the efficiency of three ionic liquids (ILs), two halogenide ILs (HILs-1, HILs-2), and one is non-halogenide IL (Non-HIL) as demulsifiers for the recovery of oil from O/W-EMUL at a concentration of 500 mg/L. The percentage demulsification efficiency (D%) (i.e., the percentage of oil removed from the O/W-EMUL) was examined using tube and bottle tests. The results of the bottle tests demonstrated that the halogenide ionic liquids (HILs) could achieve a higher D% in comparison to the Non-HIL. The D% achieved within 20 min of treatment with HILs-1, HILs-2, and Non-HIL was found to be ∼ 97.7%, 88.2%, and 85.2%, respectively. Increasing the volume of ILs ( VILs ), which are normally recycled, can help overcome the surfactant’s effect to achieve a D% > 95%. The demulsification mechanism is based on ion exchange between the anionic part of the ILs and the oil–surfactant interphase. Recycling the ILs can be enhanced by reestablishing the IL anion part using water-free inversed ion exchange mixed with salts. The results suggest that ILs can be an appropriate substitute for commercial demulsifiers. Though, further efforts are needed to produce non-toxic and cost-effective ILs with low viscosity. The efficiency of the demulsification process may be further enhanced when using ILs with other separation processes. The achieved results support upcoming research works that apply ILs for oil removal from O/W-EMUL

A novel hybrid solar chimney power plant: Performance analysis and deployment feasibility

This study presents a novel hybrid solar chimney power plant (HSCPP) design. The HSCPP preserves the typical solar chimney power plant (SCPP), with an additional seawater pool at the base and water sprinklers at the top. This new and novel design configuration offers an opportunity to run the system during the daytime as a traditional SCPP and as a downdraft cooling tower at night. The performance of the HSCPP was analyzed in 16 cities in the Kingdom of Saudi Arabia (KSA) that span the entire geographical area of the country to select the optimal location for installation. The results showed that the highest annual electrical energy production of 676.20 MWh was achieved in the southern city of Shahrurah. However, the lowest annual electrical energy production of 347.59 MWh was found at Wajh, in the west. The highest annual freshwater production was 143,898 tons at Riyadh, in the center. However, the lowest annual freshwater production was 77,868 tons at Muwayh, in the west. Furthermore, the results showed that the proposed HSCPP increased electrical power production by 55% and freshwater production by 20% when compared to traditional SCPP. In addition, an outstanding reduction in CO2 emissions by approximately 56% was associated with such an application of HSCPP. The performance of the HSCPP is very promising, however, the geographical location to install the HSCPP is performance-critical. Hence, the optimal locations were found to be from the center to the southern part of the KSA.Special thanks to Asma Khasawneh for helping with the diagrams.Scopu

Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions

The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS) cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature (TL) on Gibbs free energy related to the H2 production step were examined in detail. The cycle (ηcycle) and solar-to-fuel energy conversion (ηsolar-to-fuel) efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that ηcycle and ηsolar-to-fuel increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (TH). It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At TH=2280 K, by applying 60% heat recuperation, maximum ηcycle of 39.0% and ηsolar-to-fuel of 47.1% for the Tb-WS cycle can be attained.The authors gratefully acknowledge the financial support provided by the Qatar University Internal Grant (QUUGCENG-CHE-14/15-10).Scopu

The effect of intermediate ozonation process on improving biogas production from co-digestion of agricultural waste and manure

Anaerobic co-digestion of agricultural solid waste, wastewater, and manure was evaluated in batch reactor. The performance of anaerobic digestion (AD) was monitored by assessing the methane production potential, maximum methane production rate and methane production lag time. An intermediate advanced oxidation processes by ozone was used to increase in the amount of methane produced and reduce the AD time. The production of methane from pure substrate (cow manure and wheat straw) was found to be 325 and 130 L/kg VS, mixed substrate of wheat straw, cattle manure and wastewater generated more than 368 L/kg VS. An intermediate ozonation process between two AD processes increased the % methane recovery form the ultimate value 60-85%, and reduce the total AD time to 20 days.Scopu

Ni incorporation in MgFe2O4 for improved CO splitting activity during solar fuel production

Efficacy of the sol–gel derived Ni-doped Mg-ferrites for an enhanced CO2 splitting activity is investigated. The results allied with the characterization indicate the formation of nominally phase pure Ni-doped Mg-ferrites with a coarser particle morphology. Ni-doped Mg-ferrites are further tested for multiple thermal reduction as well as CO2 splitting steps by using a thermogravimetric analyzer. The results associated with the thermogravimetric analysis confirmed that most of the Ni-doped Mg-ferrites attained a steady TR aptitude after crossing the 5th or 6th cycle. Likewise, the CS capability of all the Ni-doped Mg-ferrites accomplished consistency after 4th cycle (except for Ni0.11Mg0.88Fe2.01O4.005). The Ni0.90Mg0.11Fe2.04O4.070 showed the highest amount of O2 release (117.1 μmol/g cycle) and CO production (210.3 μmol/g cycle) in ten consecutive thermochemical cycles. Besides, Ni0.29Mg0.72Fe1.98O3.980 indicated better re-oxidation aptitude (nCO/nO2 ratio = 1.89) when compared with other Ni-doped Mg-ferrites

Treatment of waste gas contaminated with dichloromethane using photocatalytic oxidation, biodegradation and their combinations

[Abstract] The treatment of waste gas (WG) containing dichloromethane (DCM) using advanced oxidation processes (AOPs) [UV and UV-TiO2], biological treatment (BT), and their combination (AOPs-BT) was tested. AOP tests were performed in an annular photo-reactor (APHR), while BT was conducted in a continuous stirred tank bioreactor (CSTBR). The effects of gas flow rate (Qgas), inlet DCM concentration ([DCM]i), residence time (τ), photocatalyst loading (PH-CL) and % relative humidity (% RH) on the AOPs performance and the removal of DCM (%DCMr) were studied and optimized. The UV process exhibited %DCMr ≤ 12.5 % for tests conducted at a [DCM]i ≤ 0.45 g/m3, Qgas of 0.12 m3/h and τ of 27.6 s, respectively, and < 4 % when the [DCM]i ≥ 4.2 g/m3. The UV-TiO2 achieved a %DCMr ≥ 71 ± 1.5 % at Qgas of 0.06 m3/h, [DCM]i of 0.45 g/m3, τ of 55.2 s, PH-CL of 10 g/m2, and %RH of 50, respectively. The BT process removed ∼97.6 % of DCM with an elimination capacity (EC) of 234.0 g/m3·h. Besides, the high %DCMr of ∼98.5 % in the UV-BT and 99.7 % in the UV-TiO2-BT processes confirms AOPs-BT as a promising technology for the treatment of recalcitrant compounds present in WG.Xunta de Galicia; ED431C 2017/6

Advanced wastewater treatment using microalgae: Effect of temperature on removal of nutrients and organic carbon

This study evaluated the use of mixed indigenous microalgae (MIMA) as a treatment process for wastewaters and CO2 capturing technology at different temperatures. The study follows the growth rate of MIMA, CO2 Capturing from flue gas, removals of organic matter and nutrients from three types of wastewater (primary effluent, secondary effluent and septic effluent). A noticeable difference between the growth patterns of MIMA was observed at different CO2 and different operational temperatures. MIMA showed the highest growth grate when injected with CO2 dosage of 10% compared to the growth for the systems injected with 5% and 15 % of CO2. Ammonia and phosphorus removals for Spirulina were 69%, 75%, and 83%, and 20%, 45% and 75 % for the media injected with 0, 5 and 10% CO2. The results of this study show that simple and cost-effective microalgae-based wastewater treatment systems can be successfully employed at different temperatures as a successful CO2 capturing technology even with the small probability of inhibition at high temperatures.This publication was made possible by the NPRP grant (NPRP No.: 6 - 1436 - 2 - 581) from the Qatar National Research Fund (a member of Qatar Foundation).Scopu

Application of Li-, Mg-, Ba-, Sr-, Ca-, and Sn-doped ceria for solar-driven thermochemical conversion of carbon dioxide

The redox reactivity of the Li-, Mg-, Ca-, Sr-, Ba-, and Sn-doped ceria (Ce0.9A0.1O2−δ) toward thermochemical CO2 splitting is investigated. Proposed Ce0.9A0.1O2−δ materials are prepared via co-precipitation of the hydroxide technique. The composition, morphology, and the average particle size of the Ce0.9A0.1O2−δ materials are determined by using suitable characterization methods. By utilizing a thermogravimetric analyzer setup, the long-term redox performance of each Ce0.9A0.1O2−δ material is estimated. The results obtained indicate that all the Ce0.9A0.1O2−δ materials are able to produce steady amounts of O2 and CO from cycle 4 to cycle 10. Based on the average nO2 released and nCO produced, the Ce0.899Sn0.102O2.002 and Ce0.895Ca0.099O1.889 are observed to be the top and bottom-most choices. When compared with the CeO2 material, all Ce0.9A0.1O2−δ materials showed elevated levels of O2 release and CO production

Impact of CO2 concentration and ambient conditions on microalgal growth and nutrient removal from wastewater by a photobioreactor

The increase in atmospheric CO2 concentration and the release of nutrients from wastewater treatment plants (WWTPs) are environmental issues linked to several impacts on ecosystems. Numerous technologies have been employed to resolves these issues, nonetheless, the cost and sustainability are still a concern. Recently, the use of microalgae appears as a cost-effective and sustainable solution because they can effectively uptake CO2 and nutrients resulting in biomass production that can be processed into valuable products. In this study single (Spirulina platensis (SP.PL) and mixed indigenous microalgae (MIMA) strains were employed, over a 20-month period, for simultaneous removal of CO2 from flue gases and nutrient from wastewater under ambient conditions of solar irradiation and temperature. The study was performed at a pilot scale photo-bioreactor and the effect of feed CO2 gas concentration in the range (2.5–20%) on microalgae growth and biomass production, carbon dioxide bio-fixation rate, and the removal of nutrients and organic matters from wastewater was assessed. The MIMA culture performed significantly better than the monoculture, especially with respect to growth and CO2 bio-fixation, during the mild season; against this, the performance was comparable during the hot season. Optimum performance was observed at 10% CO2 feed gas concentration, though MIMA was more temperature and CO2 concentration sensitive. MIMA also provided greater removal of COD and nutrients (~83% and >99%) than SP.PL under all conditions studied. The high biomass productivities and carbon bio-fixation rates (0.796–0.950 gdw·L−1·d−1 and 0.542–1.075 gC·L−1·d−1 contribute to the economic sustainability of microalgae as CO2 removal process. Consideration of operational energy revealed that there is a significant energy benefit from cooling to sustain the highest productivities on the basis of operating energy alone, particularly if the indigenous culture is used