Preparation of Adsorbent Fe-loaded Cellulose/Tannin and Its Adsorption Characteristics for Fluoroquinolones Antibiotics
The absorbent of Fe-loaded cellulose/bayberry tannin(Fe-CBT)was prepared via impreg-nation and in-situ reduction process,with cellulose/tannin composite aerogel(CBT)as the carrier,which then was characterized by means of scanning electron microscopy,Fourier infrared spectroscopy and X-ray energy dispersive spectroscopy.Afterwards,the adsorption characteristic of the Fe-CBT was compar-atively assessed for three typical fluoroquinolones(FQs)antibiotics,i.e.,norfloxacin(NOR),lomefloxacin hydrochloride(LOM)and levofloxacin hydrochloride(LVX).The results show that the coexistence of cat-ions Na+,K+,Mg2+and Ca2+all interferes significantly with the adsorption process.Moreover,the adsorp-tion process is an exothermic reaction that proceeds spontaneously,mainly as single-molecule layer ad-sorption,of which chemisorption is the main rate-limiting step.The quasi-secondary and Langmuir mod-els are demonstrated to fit this adsorption behavior,and the maximum theoretical adsorption capacity of 99.07,74.17 and 40.14 mg/g can be achieved for NOR,LOM and LVX at 298 K,respectively.Both NaOH and NaCl show superior elution effect on Fe-CBT,namely,after re-generation for four times with NaOH and NaCl solutions,the adsorption capacity of Fe-CBT on NOR could even be maintained>70%.In addi-tion,it is found that the removal of FQs by Fe-CBT is caused by the synergy between electrostatic gravita-tion,surface complexation,hydrogen bonding and π-π stacking.