Solar photocatalytic oxidation and removal of arsenic from ground water

In a laboratory study, the effectiveness of combined tartrate and citrate as photocatalyst in solar photocatalytic oxidation and removal of arsenic from ground water was studied and a method, using a naturally occurring tartrate-citrate photocatalyst that can be used at the household level to treat small quantities of drinking water was developed. Kinetic tests performed with 250 μg/L As(III)-spiked ground water in presence of 5 mg/L Fe(II) and 50 μM photocatalyst, showed equal efficiency of tartrate and citrate in combination for oxidation and removal of arsenic from ground water in 6 h solar illumination. Presence of silicate moderately decreased the removal of arsenic, while phosphate had more drastic effect on arsenic removal. With the increase in initial As(III) concentration above 250 μg/L, 5 mg/L Fe(II) did not achieved the removal to below 50 μg/L, although the maximum removal efficiency was 80%. Extract of tamarind (fruit of the tree Tamarindus indica), a natural source of tartrate-citrate (equivalent to 50 μM tartrate and citrate) achieved the arsenic oxidation and removal from 250-260 μg/L arsenic-bearing water to below 50 μg/L. The method performed within a 1-L closed PET bottle showed similar removal and can be applied at the household level to treat small quantities of drinking water.