Review: Efficiently performing periodic elements with modern adsorption technologies for arsenic removal.

Arsenic (As) toxicity is a global phenomenon, and it is continuously threatening human life. Arsenic remains in the Earth's crust in the forms of rocks and minerals, which can be released into water. In addition, anthropogenic activity also contributes to increase of As concentration in water. Arsenic-contaminated water is used as a raw water for drinking water treatment plants in many parts of the world especially Bangladesh and India. Based on extensive literature study, adsorption is the superior method of arsenic removal from water and Fe is the most researched periodic element in different adsorbent. Oxides and hydroxides of Fe-based adsorbents have been reported to have excellent adsorptive capacity to reduce As concentration to below recommended level. In addition, Fe-based adsorbents were found less expensive and not to have any toxicity after treatment. Most of the available commercial adsorbents were also found to be Fe based. Nanoparticles of Fe-, Ti-, Cu-, and Zr-based adsorbents have been found superior As removal capacity. Mixed element-based adsorbents (Fe-Mn, Fe-Ti, Fe-Cu, Fe-Zr, Fe-Cu-Y, Fe-Mg, etc.) removed As efficiently from water. Oxidation of AsO33- to AsO43-and adsorption of oxidized As on the mixed element-based adsorbent occurred by different adsorbents. Metal organic frameworks have also been confirmed as good performance adsorbents for As but had a limited application due to nano-crystallinity. However, using porous materials having extended surface area as carrier for nano-sized adsorbents could alleviate the separation problem of the used adsorbent after treatment and displayed outstanding removal performances.