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- Title
Oil removal from water using agricultural wastes-based adsorbents for the application in reverse osmosis desalination systems.
- Authors
Wagih, Nora; Mahmoud, Mohamed M.; Elbaz, Amro A.; EL-Moniry, Diaa
- Abstract
Egypt is facing water shortage due to limitation in the freshwater resources and the increased population growth. Thus, there is a need for developing new water resources such as the expansion in building large-scale reverse osmosis (RO) seawater desalination plants. Oil spill in the marine environment can cause severe fouling problems and make damage to the RO membranes, which increases the operating cost. The current study focuses on oil removal from water using agricultural-based adsorbents to reduce the membrane fouling in the RO systems. Three adsorbents namely: rice husk (RH), sawdust (SD) and sugarcane bagasse (SCB) were tested to remove used motor oil (UMO) and crude oil (CO) from distilled and raw seawater. Activated carbon (AC) was included in the measurements to be used as a reference case to compare with. The oil sorption removal and adsorption capacity were determined experimentally for the four tested adsorbents. The experimental parameters included: initial oil concentration (2-40 g/L), adsorbent dose (2-30 g/L), contact time (5-120 min), agitation time (0-60 min), chemical modification (acid vs. base treatment), water salinity (up to 35 g/L). The effect of the presence of other heavy metals on oil sorption removal and adsorption capacity was also investigated. The characteristics of the adsorbents surface were studied using the Fourier-transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller analysis. The results demonstrated that the adsorption removal of UMO with higher viscosity is higher than CO and always the RH exhibited the highest adsorption capacity compared to SD and SCB but about 30% less than AC. Precaution should be taken when distilled water is used rather than raw seawater because the difference could reach about 50% but it depends on the type of oil and adsorbing material. Additionally, the oil sorption removal in seawater is about 20% higher in raw seawater compared to distilled water. The oil sorption removal increased with an increase in contact time, adsorbent dosage, agitation time, and salinity, and decrease in initial oil concentration. The effect of presence of metals ions concentration in raw seawater can be neglected with the adsorbent used in the current study. The adsorption isotherm models by Langmuir described the experimental data very well while the pseudo-second-order described the kinetics data very well. The small difference in performance between RH and AC indicates that RH is very promising low-cost adsorbents for oil removal in RO desalination systems. The Gibbs free energy (ΔG) was calculated and the values were negative, indicating that the sorption process was spontaneous.
- Subjects
EGYPT; SALINE water conversion; WATER shortages; REVERSE osmosis; WATER use; LANGMUIR isotherms; SORBENTS; HEAVY oil
- Publication
Desalination & Water Treatment, 2023, Vol 316, p335
- ISSN
1944-3994
- Publication type
Article
- DOI
10.5004/dwt.2023.30200