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Aluminum hydroxide supported on zeolites for fluoride removal from drinking water

Dessalegne, Meseret, Zewge, Feleke, Diaz, Isabel
Journal of chemical technology and biotechnology 2017 v.92 no.3 pp. 605-613
X-ray diffraction, adsorbents, adsorption, aluminum, aluminum hydroxide, aqueous solutions, drinking water, fluorides, silicon, texture, water treatment, zeolites, Ethiopia
BACKGROUND: Problems of fluorosis are still affecting millions of people around the world including Ethiopia. Hence the need to find sustainable solutions is still worth investigating. In this study, commercial zeolite Y (ZY) and natural stilbite (STI) from Ethiopia are evaluated as support for aluminum hydroxide (AO) and studied for fluoride removal from aqueous solution. The composites (STI‐AO) and (ZY‐AO) are synthesized at different zeolite to AO ratios by modifying the procedure used for synthesizing AO, reported earlier. RESULTS: The X‐ray diffraction profiles show that zeolite structures are stable during modification processes. The Si/Al ratio of composites decreases as the amount of AO is increased due to increase in Al content. The PZC of STI, initially at 2.5, increased to 9.2 in STI‐AO. Textural properties of ZY and ZY‐AO proved to block certain microporosity by the AO. Optimum conditions to reduce an initial fluoride concentration of 10 mg L⁻¹ to below the WHO guideline value of 1.5 mg L⁻¹ were 2 g L⁻¹ for the 2:1 systems and 4 g L⁻¹ for the 6:1 systems. CONCLUSION: Zeolite‐AO composites have very good equilibrium fluoride adsorption capacity compared with most reported materials. Hence these materials can be considered alternative adsorbents for the removal of fluoride from drinking water. © 2016 Society of Chemical Industry