ABSTRACT
Cryogels have potential for applications in water and wastewater treatment. However, maximum levels of exposure to both incorporated materials in cryogels (i.e., nanoparticles [NPs]) and monomers, as a result of leakage, must be established before cryogel composites can be implemented in the large-scale
12.1 Introduction .................................................................................................. 332 12.2 Cryogel-Based Adsorbents ........................................................................... 333
12.2.1 Functionalized Cryogels ................................................................... 333 12.2.2 Protected Cryogels ............................................................................ 334
12.3 Composite Cryogels ...................................................................................... 335 12.3.1 Metal-Oxide Composite Cryogels .................................................... 336 12.3.2 Other Types of Composites...............................................................340 12.3.3 Cryogel Composites with Molecularly Imprinted Polymers ............ 341
12.4 Pollutant Source Determines the Adsorbent ................................................ 345 12.4.1 Industrial and Municipal Wastewater ............................................... 345 12.4.2 Point-of-Use Filters ...........................................................................346 12.4.3 Oil Removal-Taking Advantage of Cryogel Pore Space ................ 347 12.4.4 Metal Removal in Connection to Biogas Production ....................... 347 12.4.5 Microbial Cryogel Systems ............................................................... 349
12.5 Future Challenges ......................................................................................... 349 12.5.1 System Regeneration......................................................................... 349 12.5.2 Deposition ......................................................................................... 350 12.5.3 Risk Assessment ............................................................................... 351 12.5.4 Costs ................................................................................................. 352
12.6 Concluding Remarks .................................................................................... 353 Acknowledgements ................................................................................................ 354 List of Abbreviations .............................................................................................. 354 References .............................................................................................................. 355
treatment of water. Other factors, such as cost and reuse, must also be studied for each specific adsorbent. One of the greater advantages of cryogels is the flexibility of their preparation. The material can be prepared as monoliths, discs, beads or particles, to suit specific requirements. Results on a laboratory scale may be different from those obtained when treating real water and wastewater due to differences in scale and water chemistry. The social acceptance of the technology and its overall environmental impact must also be assessed. This chapter starts with describing how cryogel materials have been developed from their initial applications in water treatment to more recent developments. This is followed by current published results obtained from the treatment of water from different sources, including both lab-scale evaluations as well as real water samples. As the main application of cryogels within water treatment today is as adsorbent materials, these will be given the main focus for this chapter but still include more recent research results from applications regarding disinfection and oil absorption. The main pollutants of interest for this chapter are inorganic pollutants such as metals and metalloids (e.g. cadmium and arsenic), but organic contaminants are also mentioned. Future challenges in this area today, regarding cryogel applications, cover the need for system regeneration, the deposition of the pollutant and, finally, the total cost of the treatment.
