Novel nanostructured iron oxide cryogels for arsenic (As(III)) removal

[Display omitted] •Novel macroporous cryogels containing nanostructured iron oxide were synthesized.•Iron oxide was uniformly dispersed in the cryogel matrix.•The cryogels have high mechanical stability and low flow-through resistance for solutes through the matrix.•The arsenic adsorption capacity of the cryogels was high.•The cryogels have potential as effective nano-based adsorption devices for water treatment. Novel macroporous iron oxide nanocomposite cryogels were synthesized and assessed as arsenite (As(III)) adsorbents. The two-step synthesis method, by which a porous nanonetwork of iron oxide is firstly formed, allowed a homogeneous dispersion of the iron oxide in the cryogel reaction mixture, regardless of the nature of the co-polymer forming the cryogel structure. The cryogels showed excellent mechanical properties, especially the acrylamide-based cryogel. This gel showed the highest As(III) adsorption capacity, with the maximum value estimated at 118 mg/g using the Langmuir model. The immobilization of the nanostructured iron oxide gel into the cryogel matrix resulted in slower adsorption kinetics, however the cryogels offer the advantage of a stable three-dimensional structure that impedes the release of the iron oxide nanoparticles into the treated effluent. A preliminary toxicity evaluation of the cryogels did not indicate any apparent inhibition of human hepatic cells activity, which together with their mechanical stability and high adsorption capacity for As(III) make them excellent materials for the development of nanoparticle based adsorption devices for drinking water treatment.