English abstract
Water bodies are often polluted with various inorganic contaminants such as, Arsenic
(As) and Bromate (BrO3
−). Arsenic can be found in nature whereas, bromate is
generated as a byproduct of disinfection process. The World Health Organization
(WHO) set the allowable limit of arsenic and bromate to be less than 10 ug/L in
drinking water. The long-term exposure to high concentration of the contaminants can
pose negative health effects to human like cancer. It was reported that, bromate
concentration was found to exceed the WHO standard in one of the local bottled water
brands in Oman. Therefore, this research project aims to remove Arsenic and Bromate
using date palm and mesquite biochar before and after Fe-enhancement through batch
experiment by considering three adsorbent doses of 10, 50 and 100 g/mL. Under
pristine biochar the initial concentrations of As were 10, 50 and 100 mg/L, and for
BrO3 were 0.5, 10 and 100 mg/L. For the enhanced biochar, the initial concentrations
of As were 5, 10, 50, 70 and 100 mg/L, and for BrO3 were 0.5, 10, 30, 60 and 100
mg/L. The removal efficiency comparison between pristine and Fe enhanced date palm
and mesquite biochar were done for the removal of both As and BrO3 respectively. It
was found that, Fe-enhanced date palm biochar had 16% higher removal efficiency of
Arsenic than pristine biochar. While pristine mesquite biochar had 27% higher removal
efficiency than enhanced mesquite biochar. For BrO3, pristine biochar had 67.6 %
higher removal efficiency than enhanced date palm biochar. While pristine mesquite
performs much better than Fe-enhanced biochar at high BrO3 concentration. Ion
Chromatography (IC) and Inductively Coupled Plasma (ICP) were used to determine
As and BrO3
− concentrations respectively. The isotherm models of Langmuir and
Freundlich parameters were obtained to determine the best adsorption modeling fit.
The results showed that Fe-enhanced mesquite biochar has the ability to reduce As
concentration up to 46.5% due to the great increase in oxygen containing functional
group. Whereas BrO3
− can be removed better by pristine/ unmodified date palm and
mesquite biochar due to its low polarity. The equilibrium sorption data were well fitted
to the two As isotherm models. Freundlich was found to have the highest R
2= 0.9995
by enhanced mesquite biochar. While Langmuir model can describe the removal BrO3
better than Freundlich model in which the regression coefficient was equal to 0.9993,
which confirm monolayer coverage of BrO3
−onto enhanced date palm biochar.
