The utilization of cross-linked gelatin/PAMAM aerogels as heavy metal ions bio-adsorbents from aqueous solutions

Three bio-based aerogels were prepared using a cross-linked blend of gelatin and different ratios of poly(amidoamine) hyperbranched polymer (PAMAM) via freeze-drying technique. These aerogels are assigned as cGel/PAM 1, cGel/PAM 2, and cGel/PAM 3. Aerogel of cross-linked gelatin cGel was prepared for comparison. The fabricated aerogels were characterized using FT-IR and determination of their nitrogen content. The macro-porous structures and the surface areas were investigated using the scanning electron microscope, Brunauer, Emmett and Teller (BET), and Barrett, Joyner, and Halenda (BJH) equations. The adsorption efficiencies of heavy metal ions Cr(VI) and Cd(II) were assessed in terms of the contact time and dose-effect. The adsorption results of the heavy metal ions were fitted using Freundlich and Langmuir models. The adsorption isotherm data of cGel/PAM 3 aerogel are well fitted using Langmuir model ( R 2 = 0.99 and 0.981) and adsorption capacity ( q max ) 125.0 and 142.0 mg/g for Cr(VI) and Cd(II) ions, respectively. Freundlich model ( R 2 = 0.989 and 0.986 for Cr(VI) and Cd(II) ions, respectively) has been fitted with the adsorption results. The well-fitting of the Freundlich adsorption isotherm demonstrates the favorable adsorption using this promising aerogel that contains active sites with different energies. The aerogel cGel/PAM 3 was showed the highest adsorption efficiency of 98% using a 1 g/L dose within 60 min.