Iota-carrageenan based magnetic aerogels as an efficient adsorbent for heavy metals from aqueous solutions

Magnetic aerogels were prepared via physical cross-linking of Iota-carrageenan and polyamidoamine (PAMAM) dendrimer using different amounts of magnetic nanoparticles (1, 3 and 5%). A blank sample of chemically cross-linked Iota-carrageenan was prepared for comparison. The prepared magnetic nanoparticles and aerogels were fully characterized using particle size analyzer, X-ray diffraction (XRD), vibrating Sample Magnetometer (VSM), FT-IR, SEM and energy-dispersive X-ray (EDX). The surface area and porosity were calculated using Brunauer, Emmett, and Teller (BET), Barrett, Joyner and Halenda (BJH) equations. The nitrogen contents of the aerogels were determined using the Kjeldal method. These aerogels are environmentally safe, eco-friendly and cheap. The adsorption behavior of the aerogels was evaluated for Cr (VI), Co2+, Cu2+, Cd2+, Mn7+, and Alphanol fast blue dye. The synergetic effect for the presence of the chelating groups with different natures (i.e. sulfate and amine) was revealed via the high ability of the aerogels to remove the cations and oxyanions in a similar manner. The prepared aerogels had high removal efficiency with selectivity order Co2+ > Cu2+ > Mn7+ > Cd2+ > Cr (VI). The maximum adsorption efficiency of Co2+ was 99% achieved by using CAR M3.