Effects and behaviors of Microcystis aeruginosa in defluorination by two Al-based coagulants, AlCl3 and Al13

Wu, Lifeng; Xu, Hengyong; Li, Chunfu; Demissie, Hailu; Li, Kun; Fan, Hongsong

doi:10.1016/j.chemosphere.2021.131865

Cited by 10 publications

(2 citation statements)

References 61 publications

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“…Considering the stronger complexing affinity of CDTA toward aluminum over fluoride, we hypothesized that nonexchangeable fluoride (with an ionic radius of 0.13 nm) might be incorporated inside polyaluminum, and its exchange with CDTA was inhibited. 46 To verify this hypothesis, we prepared high-purity Al b for coagulation tests, 15,47 and the aluminum species in the supernatant were characterized by ESI-MS. Al b was chosen as the coagulant due to its predominant composition of Al 13 with a well-documented molecular structure. 48,49 As illustrated in Figure 3e, the peaks at mass-to-charge ratios (m/z) of 267, 273, 279, 285, 291, and 297 belonged to Al 13 clusters.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Formation of Aluminum–Fluoride Complexes Compromises Defluoridation Efficiency of Aluminum-Based Coagulation

Deng,

Xu,

Wei

et al. 2024

Environ. Sci. Technol.

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Aluminum-based coagulation has long been regarded as a reliable and cost-effective process for the defluoridation of industrial effluents. However, such a well-recognized viewpoint is challenged by the underestimation of fluoride levels in treated effluents. Herein, we developed a systematic protocol to distinguish different fluoride species, including free F − , exchangeable fluoride (EF), and nonexchangeable fluoride (NEF). We demonstrated that EF forms complexes with octahedral aluminum (AlO 6 ) on the surface of polyaluminum and can be exchanged with (1,2-cyclohexylenedinitrilo)-tetraacetic acid (CDTA). However, NEF is incorporated with tetrahedral aluminum (AlO 4 ) at the core of polyaluminum, as confirmed by 19 F/ 23 Al NMR and ESI-MS analysis, and cannot be exchanged with CDTA due to steric hindrance. Increasing the aluminum coagulant dosage effectively reduced free F − levels in photovoltaic and electroplating effluents to below 1 mg/L. However, the total fluoride content, with over half in the form of EF and NEF, was above 2 mg/L, exceeding the discharge limit regulated by many local governments of China. Furthermore, both EF and NEF can gradually transform to free F − in natural waters. Our findings indicate that aluminum-based coagulation inevitably accompanies the formation of substantial amounts of EF and NEF, compromising its defluoridation efficiency toward industrial effluents.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Formation of Aluminum–Fluoride Complexes Compromises Defluoridation Efficiency of Aluminum-Based Coagulation

Deng,

Xu,

Wei

et al. 2024

Environ. Sci. Technol.

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“…Hence, considerable efforts have been dedicated to removing fluoride (Y. Xiang et al 2022). Various composite materials have been employed for this purpose, yielding promising outcomes.…”

Section: Introductionmentioning

confidence: 99%

Single and binary adsorption experiments and modeling of arsenic and fluoride using activated carbon as adsorbent

Acharya,

jeppu,

Raju

et al. 2023

Preprint

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Arsenic and fluoride are co-occurring contaminants in groundwater. This research investigated the competitive adsorption of arsenic and fluoride from aqueous solution on activated carbon. Batch experiments were used to study the behavior and efficiency of activated carbon to know the influence of adsorbent dosage, contact time, and solution pH of arsenic and fluoride in single and binary component systems. At optimum values, in single-component systems, activated carbon demonstrates efficient adsorption of arsenic and fluoride, achieving a percentage removal of 93.56% for arsenic and 72% for fluoride. Similarly, in binary-component systems, the percentage removal of As(V) is found to be 71.91%, while fluoride is removed at a rate of 90%. Kinetic studies showed that adsorption followed a pseudo-second-order kinetic mode, which suggests chemisorption. Langmuir, Freundlich, Toth, Redlich Petersons, and Modified Langmuir Freundlich (MLF) models were used to interpret the single adsorption isotherm data. The maximum uptake of arsenic and fluoride was 3.58 mg/g and 2.32 mg/g, respectively. It was noted that the Modified Langmuir Freundlich isotherm model gave a better fit with higher R2 and lower RMSE values. Extended Langmuir and Extended Freundlich isotherm models were used to interpret the competitive adsorption data. The competitive studies showed selectivity of adsorption for As(V) > F which suggested that the affinity of activated carbon was greater towards As(V) than fluoride. Also, As(V) showed antagonistic behavior with F.

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Defluoridation by positive single-pulse current electrocoagulation from photovoltaic wastewater: Energy consumption assessment and mechanism analysis

Wu,

Shi,

Sun

et al. 2024

Chemosphere

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Effects and behaviors of Microcystis aeruginosa in defluorination by two Al-based coagulants, AlCl3 and Al13

Cited by 10 publications

References 61 publications

Formation of Aluminum–Fluoride Complexes Compromises Defluoridation Efficiency of Aluminum-Based Coagulation

Formation of Aluminum–Fluoride Complexes Compromises Defluoridation Efficiency of Aluminum-Based Coagulation

Single and binary adsorption experiments and modeling of arsenic and fluoride using activated carbon as adsorbent

Defluoridation by positive single-pulse current electrocoagulation from photovoltaic wastewater: Energy consumption assessment and mechanism analysis

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