Performance and Mechanism of L-arginine Modifed Alginate Aerogels for Adsorption of Cadmium and Copper Ions

Heavy metals existed in wastewater could bio-accumulate in aquatic organisms and bring a serious threat to human health. Many methods and adsorbents have been explored to remove heave metals from wastewater, however, developing new adsorbents with satisfied adsorptive property still needs further study. An eco-friendly aerogel adsorbent (CA-Arg) was synthesized through chemical grafting between sodium alginate and L-arginine, which showed outstanding adsorption efficiencies of Cd²⁺ and Cu²⁺ ions. The adsorption kinetics and thermodynamics were investigated, and results demonstrated that the adsorption processes were consistent with pseudo-second-order kinetics and Langmuir isotherm equation, illustrating the adsorption processes of target metals were endothermic and spontaneous. The maximum adsorption capacity of Cd²⁺ and Cu²⁺ could reach 248.11 mg·g^− 1 and 237.45 mg·g^− 1, respectively. In addition, the possible adsorption mechanism between the surface functional groups of CA-Arg aerogels and metal ions was explored. This biomass-based aerogel provided a promising adsorbent for the treatment of industrial heavy metals.