Vol. 25, No. 2 (2026), IA26791 https://doi.org/10.24275/rmiq/IA26791

Aluminum – modified rice husk biochar for effective fluoride adsorption

 

Authors

G. X. Martinez-Paredes, L. Lopez N.

Abstract

Aluminum modified rice husk biochar (BC-Al) was prepared as an alternative renewable adsorbent to treat fluoride contaminated drinking water. The adsorbent was characterized by Brunauer–Emmett–Teller (BET) method, point of zero charge (PZC), scanning electron microscopy (SEM–EDS) and Fourier-transform infrared spectroscopy (FTIR). Batch and column experiments were realized in order to determine the fluoride removal efficiency at different operating conditions. The results showed that BC-Al has a surface area of 39.35 m2/g, a PZC of 4.9 and the presence of aluminum in its surface. The BC-Al removes > 90 % of the fluoride present in water, follows a pseudo second order kinetic and fits the Sips isotherm model. The maximum adsorption capacity was 5.163 mg/g, working in a pH range from 2.5 to 7.0, with an adsorbent dose of 3.33 g/l and a contact time of 9 hours. The HCO3- has a negative effect on fluoride removal efficiency. In column experiments, the maximum adsorption capacity was 2.997 mg/g according to the logarithmic Thomas model. It was estimated by scaling up calculations that 85.78 liters of water could be treated in a time of 6.80 hours in a column with about 1 kg of BC-Al at pilot level.

Keywords

Adsorption, aluminum, biochar, fluoride, rice husk.

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