Selective adsorption of tetracycline by b-CD-immobilized sodium alginate aerogel coupled with ultrafiltration for reclaimed water
Authors: Xi Quan, Jun Zhang, Linlin Yin, Wei Zuo, Yu Tian
In this work, a novel composite material based on b-cyclodextrin-immobilized sodium alginate aerogel (b-CD/NaAlg) was developed utilizing cross-linker of epichlorohydrin and applied as an adsorbent to remove tetracycline antibiotics from reclaimed wastewater. A series of characterizations were utilized to confirm the successful synthesis of the adsorbent and this b-CD/NaAlg presented a three-dimensional network at the nanoscale or microscale. Under optimal conditions (pH ¼ 4, t ¼ 8 h, b-CD: NaAlg ¼ 9, adsorbent dosage ¼ 1.5 g$L-1), the maximum removal rate of b-CD/NaAlg to tetracycline was 70%. The adsorption behavior of tetracycline on b-CD/NaAlg conformed to the Freundlich isotherm model (R2 ¼ 0.9977) and the pseudo-second-order kinetic model (R2 ¼ 0.9993). Moreover, the adsorbent still removed 55.3% of tetracycline after five cycles. Specially, the adsorbent was integrated with ultrafiltration to adsorb tetracycline antibiotics from simulated reclaimed wastewater, and the removal rate of tetracycline reached 78.9% within 2 h. The existence of Cr (VI) had a negligible impact on tetracycline removal, while the presence of humic acid exhibited a promoting effect. The possible adsorption mechanisms were also elucidated through X-ray photoelectron spectroscopy and density functional theory analysis. In summary, b-CD/NaAlg represents an environmentally friendly, efficient, and sustainable adsorbent for removing tetracycline antibiotics from reclaimed water.
