Arsenic is a toxic contaminant commonly found in drinking water, which could lead to deleterious health effects including cancer, cardiovascular disease, kidney diseases etc. In this study Fe3O4 (magnetite) was chemically co-precipitated on commercial high surface area (700 m2/g) Douglas fir biochar (MBC) (syn gas by product) using FeCl3 and FeSO4 followed by NaOH base treatment. MBC was tested for it’s As(V) removal in both batch and column sorption under different initial solution pH, equilibrium time, initial concentrations, in the presence of competitive contaminants (phosphate, selenate, molybdate, chromate, nitrate, chloride, fluoride, copper and methylene blue). Also, ionic strength, dose, dose volume, performance in real water matrices, cyclic sorption, fixed-bed column sorption were assed with a special attention to scaled-up applications. MBC was able to reduce the As(V) concentrations down to WHO drinking water standard limits (&lt;10 ppb). The MBC redox transformation studies on As(III) has shown the MBC has a potential to convert As(III) to less toxic As(V). Primary sorption mechanism is sought to be chemisorption onto surface iron hydroxyl groups. In addition, stoichiometric Fe-As compound formation was considered with a comprehensive iron leaching study. These preliminary experiments suggest that MBC has a great potential to provide As(V) free drinking water. Future experiments will be focused on engineering the MBC in large scale for commercialization.

Sorption of As(V) using Fe3O4 nanoparticles dispersed on Douglas fir biochar

ACS Fall 2021

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