Facile preparation of regenerative environmentally responsive sodium alginate aerogel and its efficient adsorption toward copper ions

Abstract

There was an urgent need to develop facile and efficient treatment technologies to remove copper ion (Cu²⁺) from wastewater resources. In order to overcome the technical bottleneck in desorption and regeneration of adsorbents, a composite aerogel of sodium p-styrenesulfonate (SSS), N-isopropylacrylamide (NIPAM), and sodium alginate (SA) (denoted as SA/P(NIPAM-co-SSS)) was prepared in a simplified manner, and it demonstrated excellent pH- and temperature-responsive properties. The resulting aerogel was systematically analyzed by a series of characterization methods, and its adsorption performance toward Cu²⁺ was detailedly investigated. The experimental results demonstrated that adsorption capacity of aerogel could reach 142.85 mg/g when molar ratio of NIPAM/SSS was 1:5. The adsorption behaviors could be well fitted by pseudo-second-order kinetic equation and Langmuir model, indicating the interaction between SA/P(NIPAM-co-SSS) and Cu²⁺ could be attributed to coordination, electrostatic interactions, and ion-pair formation. Even after five adsorption-desorption cycles at pH = 2 and 40 °C, adsorption capacity of SA/P(NIPAM-co-SSS) could maintain more than 85 % of initial adsorption capacity, implying excellent regeneration performance owing to its environmental responsiveness. Based on the unique environmentally responsive characteristics and superior regeneration ability, SA/P(NIPAM-co-SSS) could be expected to play a crucial role in the field of environmental treatment, especially in efficient removal of Cu²⁺.