Simultaneous Removal of As(III) and Fluoride Ions from Water Using Manganese Oxide Supported on Graphene Nanostructures (GO-MnO2)

Abstract

In the present research, the use of manganese oxides supported on graphene nanostructures (GO-MnO2), which support the synergistic action of adsorption and oxidation, in the combined removal of arsenic and fluoride from drinking water was studied. The simultaneous occurrence of fluoride and arsenic in groundwater is one of the major environmental problems, occurring mainly in anhydrous regions of Latin America and the world. These pollutants cause significant health problems and are difficult to remove simultaneously from drinking water. The structure of GO-MnO2 was characterized by the application of FTIR, EDS and SEM techniques. The effects of the adsorbent’s dosage, the pH value, the contact time and the initial concentrations of As(III) and F ions (F−) were examined with respect to the removal of As(III) and F ions. According to the results, the presence of arsenic enhances fluoride removal with increasing arsenic concentrations, and the presence of fluoride enhances arsenic removal with increasing fluoride concentrations, mainly at a neutral pH value. The co-presence removal efficiencies were 89% (a residual concentration of 1.04 mg/L) for fluoride and about 97% (a residual concentration of 2.89 μg/L) for arsenic.

Simultaneous Removal of Arsenate and Fluoride Using Magnesium-Based Adsorbents

“…Although the As valence differs from this study, Tolkou et al (2023), who conducted a study on the simultaneous removal of As(III) and F, reported that R AS increased with increasing C F0 , for example, when C AS0 = 0.1 mg/L, W Ad0 /V = 2 g/L and pH 0 =7, R AS = 84 and 98% at C F0 = 0 and 100 mg/L, respectively [22]. However, in this study, no significant increase in R AS was observed with increasing C F0 .…”

“…Tolkou et al ( 2023) also reported that R F increased with increasing C AS0 : C F0 = 10 mg/L, W Ad0 /V = 2 g/L and pH 0 =7, R F = 74.7 and 94.3% at C AS0 = 0 and 0.5 mg/L, respectively [22]. However, in this study, no significant increase in R AS was observed with increasing C F0 .…”

“…Evaluation methods similar to this study were also used by Tolou et al (2023), who studied the adsorption of As(III) and F on GO-MnO 2 [22]. They reported that the Langmuir isotherm model better fit the adsorption of As(III) in the presence of F-, and the Freundlich isotherm model better fit the adsorption of F-in the presence of As(III).…”

“…They reported that the Langmuir isotherm model better fit the adsorption of As(III) in the presence of F-, and the Freundlich isotherm model better fit the adsorption of F-in the presence of As(III). Furthermore, their study confirmed the reuse of the GO-MnO 2 adsorbent for four cycles of As(III) removal and three cycles for F ions after regeneration treatment using NaOH [22].…”

“…They reported that the optimum conditions for their process were a current density of 4.5 mA/cm 2 , an initial pH of 5, and a treatment time of 15 min, when initial concentrations of As and F were 0.08 mg/L and 5 mg/L, respectively, and under these conditions, the removal ratios of As and F were achieved at approximately 100% and 86%, respectively [21]. Tolkou et al (2023) investigated the removal of As(III) and F using manganese oxides supported on graphene nanostructures (GO-MnO 2 ) [22]. According to the results, the fluoride removal efficiency increased with increasing arsenic concentrations, and arsenic removal increased with increasing fluoride concentrations, mainly at a neutral pH value.…”