Arsenic is a poisonous and carcinogenic heavy metal that exists naturally on the earth’s crust, from where it can leach into the groundwater – a common water source worldwide. Therefore, arsenic-rich areas pose the risk of chronic exposure, which is prevented by removing arsenic from water using various technologies. Adsorption with conventional adsorbents, as activated alumina and iron-based adsorbents, is commonly applied for arsenic removal. This study introduces a nanoscale adsorbent, maghemite-magnetic nanoadsorbent, for arsenic removal. The overall aim of the study was to compile fundamental information on novel maghemite nanoparticles and their suitability for arsenic removal from water with laboratory—scale batch experiments. The study was conducted with three kinds of maghemites: sol-gel, mechanochemical, and commercial maghemite. Sol-gel maghemite was the main research target; the others were studied for reference. The research consisted of the preparation of maghemite nanoparticles and their characterization, the study of adsorption kinetics, an investigation of arsenate adsorption properties on maghemite, a determination of the adsorption mechanism, and the evaluation of maghemite stability and regeneration properties. The results indicated the applicability of sol-gel maghemite for arsenic removal by adsorption. The reasons are several: sol-gel maghemite synthesis is fast, convenient to work with and produces repeatedly high-quality particles, adsorbs arsenate satisfactorily, and there is no need for preliminary treatments prior to adsorption experiments: it is easy to handle and separate via an external magnet, it maintains its initial arsenate uptake capacity after six regeneration cycles, and it is stable, which are important factors for cost-effectiveness. And it produces only a small amount of “arsenate-maghemite” waste. Moreover, sol-gel maghemite is competitive with activated alumina in adsorbent properties. Both adsorbents need careful monitoring due to pH control, interference of other ions, and regeneration. Activated alumina can remove slightly more arsenate than sol-gel maghemite, but sol-gel maghemite is more stable, forms less waste, and is separated simply and rapidly by external magnet.
|Translated title of the contribution||Arsenaatin poistaminen vedestä adsorptiolla magneettisilla nanohiukkasilla (γ-Fe2O3)|
|Publication status||Published - 2013|
|MoE publication type||G5 Doctoral dissertation (article)|
- arsenic removal
- magnetic nanoparticles
- water treatment