CO2 capture and ions removal through reaction with potassium hydroxide in desalination reject brine: Statistical optimization

Previous studies have investigated the overall performance of the modified Solvay process based on a new alkaline compound, namely, KOH. Preliminary results have confirmed its high reactivity and effectiveness in capturing CO2 and managing reject brine. In this study, parametric sensitivity analysis has been carried out to optimize the operating conditions and thereby maximize CO2 capture and ions removal from high-salinity brines. Response surface methodology (RSM) analysis using the central composite design (CCD) approach was implemented to statistically determine the impact of important operating conditions, including KOH concentration (30–110 g/l), CO2 gas flow rate (400–1600 ml/min), gauge pressure (1–3 barg), and temperature (10–50 °C) on key response process output variables, such as CO2 uptake and ions reduction. The importance of these parameters and their interactions were confirmed by employing analysis of variance (ANOVA) approach at a confidence level of 95% (p < 0.05). These analyses demonstrated that under the optimized conditions of a temperature of 10 °C, gauge pressure of 2.1 barg, CO2 gas flow rate of 848.5 ml/min, KOH concentration of 110 g/l, and an inert mixing particle volume fraction of 15%, a maximum CO2 uptake value of 0.58 g/g KOH, maximum sodium (Na+) removal of 44.1%, chloride (Cl−) removal of 40.1%, calcium (Ca2+) removal of 100%, and magnesium (Mg2+) removal of 99.8% were achieved. The characterization of the collected solid products at optimum conditions revealed the production of valuable and useful products, particularly sodium and potassium bicarbonates, in addition to KCl.Open Access funding is provided by the Qatar National Library.Scopu

Comprehensive optimization of the dispersion of mixing particles in an inert-particle spouted-bed reactor (Ipsbr) system

Effective gas dispersion and liquid mixing are significant parameters in the design of an inert-particle spouted-bed reactor (IPSBR) system. Solid particles can be used to ensure good mixing and an efficient rate of mass and heat transfer between the gas and liquid. In this study, computational fluid dynamics (CFD) coupled with the discrete phase model (DPM) were developed to investigate the effect of the feed gas velocity (0.5-1.5 m/s), orifice diameter (0.001-0.005 m), gas head (0.15-0.35 m), particle diameter (0.009-0.0225 m), and mixing-particle-to-reactor-volume fraction (2.0-10.0 vol.%) on the solid mass concentration, average solid velocity, and average solid volume fraction in the upper, middle, and conical regions of the reactor. Statistical analysis was performed using a second-order response surface methodology (RSM) with central composite design (CCD) to obtain the optimal operating conditions. Selected parameters were optimized to maximize the responses in the middle and upper regions, and minimize them in the conical region. Such conditions produced a high interfacial area and fewer dead zones owing to good particle dispersion. The optimal process variables were feed gas velocity of 1.5 m/s, orifice diameter of 0.001 m, gas head of 0.2025 m, a particle diameter of 0.01 m, and a particle load of 0.02 kg. The minimum average air velocity and maximum air volume fraction were observed under the same operating conditions. This confirmed the novelty of the reactor, which could work at a high feed gas velocity while maintaining a high residence time and gas volume fraction.This research was funded by the ADNOC Refining Research Center, Abu Dhabi, United Arab Emirates, grant number 21N224, https://dx.doi.org/10.13039/501100002672 (accessed on 20 September 2021). The authors would like to express their sincere gratitude to Jawad Mustafa from Chemical Engineering Department at the UAE University for his valuable help and assistance.Scopu

Klason Method: An Effective Method for Isolation of Lignin Fractions from Date Palm Biomass Waste

Klason lignin extraction method is one of the robust techniques for isolation of lignin from lignocellulosic palm biomass waste for future production of High Value Chemicals (HVCs). To elucidate the mechanism of hemicellulose and cellulose glycosidic bond distraction, lignocellulos

Computational fluid dynamics simulation of an Inert Particles Spouted Bed Reactor (IPSBR) system

A novel system for contacting gases and liquids, suitable for many applications involving gas-liquid contact such as CO2 capture and brine desalination, has been simulated and experimentally validated. The system comprises a vertical vessel with gas and liquid ports and inert particles that enhance mixing and provide a high gas-liquid interfacial area. A low gas flow rate was statistically demonstrated and experimentally verified to be the optimum condition for CO2 capture and brine desalination; however, the gas velocity can have a considerable effect on the motion of inert particles inside the reactor. Uniform particles motion ensures good mixing within the reactor and hence efficient absorption and stripping process. A computational fluid dynamics (CFD) model, namely Eulerian model, presented in this paper, will help demonstrate the effect of mixing particles at specific conditions on the gas and liquid velocities inside the reactor, gas and liquid volume distribution through reactor, and eddy viscosities stresses of the mixing particles. A mesh-independent study was conducted to demonstrate the independency of mesh structure and size on the output responses. A quasi-steady state was attained to ensure the stability and feasibility of the selected model. The assembled model exhibits remarkable applicability in determining the optimum mixing particles densities, volume ratios, and sizes to ensure best velocity distribution and gas spreading inside the reactor and accordingly enhance the associated chemical reactions.Research funding: Abu Dhabi National Oil Company, Refining Research Center, Abu Dhabi, UAE (Grant no. 21N224). https://dx.doi.org/10.13039/501100002672 .Scopu

Koh-based modified solvay process for removing na ions from high salinity reject brine at high temperatures

The traditional Solvay process and other modifications that are based on different types of alkaline material and waste promise to be effective in the reduction of reject brine salinity and the capture of CO2 . These processes, however, require low temperatures (10-20? C) to increase the solubility of CO2 and enhance the precipitation of metallic salts, while reject brine is usually discharged from desalination plants at relatively high temperatures (40-55? C). A modified Solvay process based on potassium hydroxide (KOH) has emerged as a promising technique for simultaneously capturing carbon dioxide (CO2 ) and reducing ions from reject brine in a combined reaction. In this study, the ability of the KOH-based Solvay process to reduce brine salinity at relatively high temperatures was investigated. The impact of different operating conditions, including pressure, KOH concen-tration, temperature, and CO2 gas flowrate, on CO2 uptake and ion removal was investigated and optimized. The optimization was performed using the response surface methodology based on a central composite design. A CO2 uptake of 0.50 g CO2 /g KOH and maximum removal rates of sodium (Na+ ), chloride (Cl? ), calcium (Ca2+ ), and magnesium (Mg2+ ) of 45.6%, 29.8%, 100%, and 91.2%, respectively, were obtained at a gauge pressure, gas flowrate, and KOH concentration of 2 bar, 776 mL/min, and 30 g/L, respectively, and at high temperature of 50? C. These results confirm the effectiveness of the process in salinity reduction at a relatively high temperature that is near the actual reject brine temperature without prior cooling. The structural and chemical characteristics of the produced solids were investigated, confirming the presence of valuable products such as sodium bicarbonate (NaHCO3 ), potassium bicarbonate (KHCO3 ) and potassium chloride (KCl).Scopu

A process for CO2 capture and brine salinity reduction through reaction with potassium hydroxide: A multi-stage evaluation

Solvay and modified Solvay processes are facing a major challenge in reducing brine salinity to a level suitable for agriculture and industry. This challenge arises as a result of competing reactions and mixing limits between CO2 gas and brine. Another challenge is the high solubility of sodium bicarbonate (NaHCO3), which results in a low overall desalination efficiency. Previous studies established the effectiveness of a modified Solvay process based on potassium hydroxide (KOH). The first objective of this study is to evaluate a multi-stage treatment for a modified Solvay process on the basis of potassium hydroxide (KOH) to achieve an additional reduction in ion removal from high-salinity brines and an increase in CO2 capture as compared to previously obtained under optimal operating conditions. Three different methods were investigated. The first method evaluated the effectiveness of adding ammonium bicarbonate (NH4HCO3) in reducing the solubility of NaHCO3. Even though the Na+ and Cl? concentrations were reduced by 56.2% and 40%, respectively, the total CO2 uptake slightly improved by 1.2% (67.8 g CO2/1000 ml of treated brine). In the second method, the addition of extra KOH in subsequent stages was investigated to overcome the pH reduction observed in the first method. There was an ? 47.3% improvement in CO2 uptake from the first method. Furthermore, the percentages of Na+ and Cl? removal were increased to 65% and 64.5%, respectively. In the third method, the recovery of Ca2+ and Mg2+ was approximately 76.3% and 94.6%, respectively, following the pre-treatment step (filtration), followed by the same stages as in the second method. Reducing these ions decreased the competitive reactions and thus increased CO2 solubility and reactivity with KOH, resulting in higher cumulative CO2 uptake from all stages to 108.2 g CO2/1000 ml, which was 8.3% more than the second method. Additionally, solid products were characterized using scanning electron microscopy, X-ray diffraction, FTIR and Raman analysis. Finally, the dynamic behaviour of the reactor was evaluated using step changes in the inlet gas and liquid flow rate. The results are promising in terms of the reactor system's adaptability to large-scale processes.The authors would like to acknowledge the financial support provided by United Arab Emirates University , grant number 12N041 .Scopu

ASIMETRIJA ŠIRINE I DUŽINE OTOLITA ODRASLIH TELEOSTIDA (Beryx splendens LOWE, 1834) (PORODICA:BERCIDAE) ULOVLJENIH UZ OBALU ARAPSKOG MORA U OMANU

Fluctuating asymmetry was described for the otolith width and length of adult teleost Beryx splendens. The results showed that the level of asymmetry of the otolith width was the highest among the two asymmetry values obtained for the otolith of B. splendens. For the otolith width character, the results showed that the level of asymmetry at its highest value in fish ranging in length between 191–200 mm and in its lowest value in fish ranging in length between 121–180 mm. For the otolith length, the highest value of asymmetry is noticed in fish ranging in length between 231–244 mm and the lowest value in fish within the length of 121–190 mm. The possible cause of the asymmetry in this species has been discussed in relation to different pollutants and their presence in the area. No trend of increase in the asymmetry values with the fish length was noticed for the otolith width, but there is a weak trend of increase with the fish length in case of otolith length character.U radu je prikazana promjena asimetrije širine i dužine otolita odraslih primjeraka Beryx splendens. Dobiveni rezultati pokazuju da su vrijednosti asimetrije širine bile više u riba koje su bile duge između 191 i 200 mm, a kod riba dužine između 121 i 180 mm vrijednosti su bile niže. Vrijednosti dužina otolita bile su više u riba dugih između 231 i 244 mm, a u riba dužine između 121 i 190 mm vrijednosti bile su niže. Mogući uzrok spomenute asimetrije razmatran je u odnosu na različite onečišćivače i njihovu prisutnost u tom području. Nije primijećeno povećanje vrijednosti asimerije širine otolita s obzirom na dužinu riba, ali je zapaženo slabo povećanje vrijednosti dužine otolita u odnosu na veličinu riba

Effective and sustainable adsorbent materials for oil spill cleanup based on a multistage desalination process

Oil spills, which are often caused by crude oil transportation accidents, contaminate coastal waters and land and can harm aquatic life, seabirds, humans, and the entire ecosystem. Ocean currents and wind complicate oil spill cleanup and extend the oil spill area. This study proposes a new approach to control oil spills using solids recovered from the treatment of reject brine through a novel multistage desalination process. The aim is to produce applicable adsorbent for oil spill cleanup especially in the final cleaning stages. The multistage desalination process is based on the electrochemical treatment of high-salinity reject brine and Solvay and modified Solvay liquid effluents in a closed Plexiglas electrocoagulation cell. After the electrochemical treatment, the collected solids were dried and ground for utilization as adsorbents in oil spill cleanup. Results were promising for the adsorbent produced from the electrochemical treatment of the modified Solvay effluent. A maximum adsorption capacity of 2.8 g oil/g adsorbent was achieved, with an oil recovery of 98%. In addition, the regenerated solids after toluene extraction process were recycled and achieved an adsorption capacity of 2.1 g oil/g adsorbent in the second oil spill clean-up cycle. The structural and chemical characteristics of the adsorbents produced from the multistage desalination process were investigated using X-ray powder diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. Results support the adoption of the collected solids as effective oil-adsorbent materials.The authors wish to thank Dr. Hussain Awad from the Chemical and Petroleum Engineering Department at UAE University for his help.Scopu