Super Absorbent Polymers (SAPs) are a class of three-dimensionally linked polymers that absorb large amounts of liquid relative to their own weight. When exposed to water, aqueous solutions, or oils, the polymers absorb relatively large amounts of liquid, up to 500 times their initial volume, while increasing the total weight of the system by a relatively small percentage. Superabsorbent polymers were developed in the 1960s by the USDA as a way to increase water retention in soil. As the technology developed, SAPs found applications in disposable hygienic products, replacing cellulose- and fiber-based products that absorbed up to only 20 times their weight. 
SAPs used for hazardous waste remediation and disposal present an alternative to the conventional method of using mineral-based absorbents. These SAPs have proven to be more effective at stabilizing the waste, fixing it within the polymers, and resulting in only a small increase in the total weight of the system compared to conventional methods. M2Polymers, Inc., a company that specializes in SAPs for applications like low-level radioactive waste stabilization and disposal, has used their products succesfully in the field. One example is the use of their WasteLock SAP to stabilize Cadmium, Chromium, and other soluble metals from sludge found on a former nuclear component manufacturer's site in order to pass the Toxic Characteristic Leaching Procedure (TCLP) required for acceptance to a disposal facility. The SAP was added to the waste through a series of troughs and mixing paddles. The stabilized mixture was then transferred to shipping containers to be transported to the disposal site, where all containers passed the TCLP and Paint Filter test. The estimated cost savings due to the neglible weight increase yielded by the SAPs compared to the conventional mineral-based absorbents is $2-3 Million. In other cases, this client had used mineral-based absorbents and the waste did not pass TCLP and was refused by waste facilities. Implementing the use of SAPs allowed the client's waste to pass TCLP and and to be transported at a much lower cost due to neglible weight increase from SAPs. For more information about this application of SAPs, visit: http://www.M2Polymer.com. For more information about SAPs for agricultural applications visit: http://www.watersorb.com.
SAPs are manufactured synthetically through polymerization, the process of reacting monomer molecules together in a chemical reaction to form three-dimensional polymer chains. They require the addition of small molecules to cross-link polymers together and the neutralization of the carboxyl acid groups along the polymer 'back bone'. These changes allow SAPs to function by drawing liquid in through osmosis along the neutralized 'back bone' of the polymer and forcing the SAP to expand, rather than separate, due to the cross-linking of the polymers that holds them together. With this basic structure, SAPs can be uniquely formed for specific purposes. For example, SAPs used for hazardous waste remediation are often sodium-based and non-biodegradable. SAPs for this application do not release solutions once they are absorbed, lending themselves to hazardous waste remediation and disposal. SAPs used for agricultural applications are often potassium-based and releast water over time to plants. These SAPs will eventually biodegrade into non-toxic elements. Sodium-based SAPs are less suited for agricultural applications as they have a shorter effective live span and created unwanted salinity levels in the soil.
SAPs used for hazardous waste remediation and disposal present an alternative to the conventional method of using mineral-based absorbents. These SAPs have proven to be more effective at stabilizing the waste, fixing it within the polymers, and resulting in only a small increase in the total weight of the system compared to conventional methods. M2Polymers, Inc., a company that specializes in SAPs for applications like low-level radioactive waste stabilization and disposal, has used their products succesfully in the field. One example is the use of their WasteLock SAP to stabilize Cadmium, Chromium, and other soluble metals from sludge found on a former nuclear component manufacturer's site in order to pass the Toxic Characteristic Leaching Procedure (TCLP) required for acceptance to a disposal facility. The SAP was added to the waste through a series of troughs and mixing paddles. The stabilized mixture was then transferred to shipping containers to be transported to the disposal site, where all containers passed the TCLP and Paint Filter test. The estimated cost savings due to the neglible weight increase yielded by the SAPs compared to the conventional mineral-based absorbents is $2-3 Million. In other cases, this client had used mineral-based absorbents and the waste did not pass TCLP and was refused by waste facilities. Implementing the use of SAPs allowed the client's waste to pass TCLP and and to be transported at a much lower cost due to neglible weight increase from SAPs. For more information about this application of SAPs, visit: http://www.M2Polymer.com. For more information about SAPs for agricultural applications visit: http://www.watersorb.com.