Biosorption of arsenic from groundwater using Vallisneria gigantea plants. Kinetics, equilibrium and photophysical considerations

•Vallisneria gigantea plants were able to remove 1 mg of As (V) during a week.•Changes in optical properties were related to arsenic concentration in solution.•Plants translocated As from roots to fronds.•As uptake followed a first-order kinetic law.•Adsorption isotherm models described experimental data from arsenic uptake.

Arsenic (V) uptake from groundwater by using Vallisneria gigantea plants was studied using batch experiments. Reflectance and fluorescence of intact plants were investigated and changes in photophysical properties following arsenic absorption were reported. Good correlations have been found between arsenic concentration in groundwater and parameters derived from reflectance and fluorescence measurements. This system reached its equilibrium after seven days when the removal quantities were strongly dependent on the initial arsenic concentration. Interestingly, Vallisneria plants were able to accumulate from 100 to 600 mg As kg−1 in roots and fronds although the translocation factors were low (0.6-1.6). Kinetic data for biosorption process followed a first-order law. At low arsenic concentrations the uptake in plants was governed by diffusion aspects. Langmuir, Freundlich and Dubinin-Radushkevich models were applied and results demonstrated that arsenic uptake was better described by the Langmuir model. As a final remark we concluded that a plant of this species should be able to remove 1 mg As per week.

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