ABSTRACT
Arsenic is viewed as being synonymous with toxicity. Dangerous arsenic concentrations in natural waters are now a worldwide problem particularly in the countries like Bangladesh, India, the United States, Canada, etc. and is often referred to as a twenty-rst century calamity. In order to remove arsenic from polluted water to a safe level, adsorption based on nanosized metal oxide adsorbents is found to be very promising, as recent studies have reported that many metal oxide adsorbents could exhibit
Abstract .......................................................................................................................................... 413 12.1 Introduction .......................................................................................................................... 414 12.2 Characteristics of Arsenic .................................................................................................... 415
12.2.1 Chemistry and Occurrence of Arsenic in Water ...................................................... 416 12.2.2 Arsenic Toxicity and Human Health Effects ............................................................ 417 12.2.3 Regulations and Guidelines Applicable to Arsenic .................................................. 418
12.3 Technologies in Arsenic Removal ........................................................................................ 419 12.3.1 Coagulation and Flocculation ................................................................................... 419 12.3.2 Ion Exchange ............................................................................................................ 419 12.3.3 Adsorption Process ................................................................................................... 420
12.3.3.1 AC Adsorbents ........................................................................................... 420 12.3.3.2 Iron Oxide-Coated Sand Adsorbents ......................................................... 420 12.3.3.3 Metal Oxide Adsorbents ............................................................................ 421
12.3.4 Arsenic Removal Based on Membrane Technology ................................................. 422 12.3.4.1 Reverse Osmosis ........................................................................................ 422 12.3.4.2 Nanoltration ............................................................................................. 423 12.3.4.3 Ultraltration/Microltration .................................................................... 425
12.4 Adsorptive Removal of Arsenic by Mixed Matrix Membranes ........................................... 425 12.4.1 Advantages of Membrane as Host-Supported Media ............................................... 425 12.4.2 Polyvinylidene Diuoride/Zirconia Flat Sheet Membrane ...................................... 426 12.4.3 Polyethersulfone/Fe-Mn Binary Oxide Flat Sheet Membrane ................................ 428 12.4.4 Polysulfone/Zirconia Hollow Fiber Membrane ........................................................ 431
12.5 Conclusion ............................................................................................................................ 434 References ...................................................................................................................................... 434
strict regulations. However, the use of metal oxide adsorbents alone is prone to agglomeration due to van der Waals forces or other interactions, causing their high capacity and selectivity of heavy metal to decrease or even be lost. Furthermore, the small size of metal oxides has made them unable to be used in xed beds or any other ow-through systems. In view of this, integrating porous host media with metal oxide adsorbents has become a hot topic in the development of applicable and reliable treatment technology. Among the many porous supports ever investigated, the use of polymeric microporous membrane as host media for nanoparticles is reported to be advantageous and unique in arsenic removal. This chapter is intended to highlight the signicant advantages of using novel mixed matrix membranes (MMMs) in the adsorptive removal of arsenic in comparison to other treatment methods and to provide in-depth discussion on the important factors inuencing the performance of MMMs during the treatment process as well as the regeneration process of the membrane.
