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In water and wastewater, phosphate anions are considered critical contaminants because they cause algae blooms and eutrophication. The present work aims at studying the removal of phosphate anions from aqueous solutions using silica particles functionalized with polyethylenimine. The parameters affecting the adsorption process such as pH, initial concentration, adsorbent dose, and the presence of competitive anions, such as carbonate, nitrate, sulfate and chromate ions, were studied. Equilibrium studies were carried out to determine their sorption capacity and the rate of phosphate ions uptake. The adsorption isotherm data fitted well with the Langmuir and Sips model. The maximum sorption capacity was 41.1 mg/g at pH 5, which decreased slightly at pH 7. The efficiency of phosphate removal adsorption increased at lower pH values and by increasing the adsorbent dose. The maximum phosphate removal was 80% for pH 5 and decreased to 75% for pH 6, to 73% for pH 7 and to 70% for pH 8, for initial phosphate concentration at about 1 mg/L and for a dose of adsorbent 100 mg/L. The removal rate was increased with the increase of the adsorbent dose. For example, for initial phosphate concentration of 4 mg/L the removal rate increased from 40% to 80% by increasing the dose from 0.1 to 2.0 g/L at pH 7. The competitive anions adversely affected phosphate removal. Though they were also found to be removed to a certain extent. Their co-removal provided an adsorbent which might be very useful for treating waters with low-level multiple contaminant occurrence in natural or engineered aquatic systems.
Maria Xanthopoulou; Dimitrios Giliopoulos; Nikolaos Tzollas; Konstantinos Triantafyllidis; Margaritis Kostoglou; Ioannis Katsoyiannis. Phosphate Removal Using Polyethylenimine Functionalized Silica-Based Materials. Sustainability 2021, 13, 1502 .
AMA StyleMaria Xanthopoulou, Dimitrios Giliopoulos, Nikolaos Tzollas, Konstantinos Triantafyllidis, Margaritis Kostoglou, Ioannis Katsoyiannis. Phosphate Removal Using Polyethylenimine Functionalized Silica-Based Materials. Sustainability. 2021; 13 (3):1502.
Chicago/Turabian StyleMaria Xanthopoulou; Dimitrios Giliopoulos; Nikolaos Tzollas; Konstantinos Triantafyllidis; Margaritis Kostoglou; Ioannis Katsoyiannis. 2021. "Phosphate Removal Using Polyethylenimine Functionalized Silica-Based Materials." Sustainability 13, no. 3: 1502.
Chromium(VI) (Cr(VI)) is the main chromium species found in groundwater and is considered as a highly toxic and carcinogenic element to humans. In the present study, removal of Cr(VI) by coagulation with ferrous iron is studied in a continuous flow treatment unit comprising pipe flocculation reactors followed by a sand filter. The studied parameters, regarding their effect on the removal of hexavalent chromium, were the ferrous iron dose, the effect of linear velocity, and the effect of the starting Cr(VI) concentration. The experiments have shown that the Cr(VI) removal achieved was very efficient and residual Cr(VI) and total Cr concentration in the treated water was lower than 10 μg/L, provided that the required dose of ferrous iron is provided. In particular, the study demonstrated that the removal of hexavalent chromium, from initial concentration of 50 μg/L and 100 μg/L, was more than 90% with ferrous doses of 1 mg/L and 2 mg/L respectively, applying linear velocity of 8 m/h, at an initial pH value of 7.3. Iron concentration in treated water was very low, far below 200 μg/L, which is the limit for iron in drinking water. This unit comprises a simple treatment option, for applications at the household level, with minimum maintenance requirements capable of removing Cr(VI) to concentrations below 10 μg/L, which might be the future limit for chromium in drinking water.
Ioannis A. Katsoyiannis; Maria Xanthopoulou; Anastasios I. Zouboulis. Cr(VI) Femoval from Ground Waters by Ferrous Iron Redox-Assisted Coagulation in a Continuous Treatment Unit Comprising a Plug Flow Pipe Reactor and Downflow Sand Filtration. Applied Sciences 2020, 10, 802 .
AMA StyleIoannis A. Katsoyiannis, Maria Xanthopoulou, Anastasios I. Zouboulis. Cr(VI) Femoval from Ground Waters by Ferrous Iron Redox-Assisted Coagulation in a Continuous Treatment Unit Comprising a Plug Flow Pipe Reactor and Downflow Sand Filtration. Applied Sciences. 2020; 10 (3):802.
Chicago/Turabian StyleIoannis A. Katsoyiannis; Maria Xanthopoulou; Anastasios I. Zouboulis. 2020. "Cr(VI) Femoval from Ground Waters by Ferrous Iron Redox-Assisted Coagulation in a Continuous Treatment Unit Comprising a Plug Flow Pipe Reactor and Downflow Sand Filtration." Applied Sciences 10, no. 3: 802.