Structuring alginate/dopamine powder into macroscopic aerogel microsphere for exceptional removal of tetracycline from water: Performance and mechanisms

Aerogel was selected as one of IUPAC Top Ten Emerging Technologies in Chemistry in 2022, and has attracted tremendous concerns of scientists in removal of emerging contaminants. In this work a novel Fe3+ cross-linked alginate aerogel (SA/DA-Fe3+) with multiple sorption sites were facilely fabricated and applied for highly efficient removal of tetracycline (TC) from water. Results showed that Fe3+ and DA cooperatively improve adsorption of TC and TC was efficiently removed over a broad pH range of 4-8. The kinetics process can be better described by a chemisorption controlled pseudo-second-order kinetics model and Langmuir isotherm equation with characteristics of monolayer coverage. The fitted qmax value of TC at ambient temperature was 804.6 mg g-1 higher than those of other reported adsorbents. Multiple interactions including π-π EDA, complexation, hydrogen bonding, electrostatic attraction, etc. were involved in adsorption process. Moreover, SA/DA-Fe3+ aerogel exhibited satisfactory stability, reusability, and recyclability for consecutive applications. Most importantly, after consecutively running for >1000 h with dynamic sorption capacity over 500 mg g-1, the packed-column was still not saturated, manifesting its great potentials for treating actual wastewaters. Thus, above superiorities make SA/DA-Fe3+ a promising candidate adsorbent for treating TC-containing wastewater.