Removal of As(V) from aqueous solutions by iron coated rice husk
A lignocellulosic material extracted from rice husk (Oryza sativa), Vietnam, was modified as a new adsorbent for the removal of As(V) ions from aqueous solution. Iron was coated onto this adsorbent by hydrolization of ferric nitrate while adding an alkaline solution drop wise into the batch type reactor. The adsorption of As(V) ions from aqueous solution on coated rice husk was then studied at varying pH, As(V) concentrations, contact times, ionic strength, and adsorbent amounts. The minimum contact time to reach equilibrium is about 6 h. The adsorption of As(V) anions on the coated rice husk was found to be highly pH dependent due to Coulomb interactions between As(V) species in solution and positively charged surface groups RH-FeOOH, as well as formation of chelate complexes with naturally occurring carboxyl and carbonyl functional groups in the ma-trix. As(V) adsorption on Fe(III)-coated rice husk (RH-FeOOH) from aqueous solution was studied in the pH range 2–10. The mai...