Simultaneous adsorptive removal of three fluoroquinolones using humic acid modified hydrogel beads

• Published in: Environmental science and pollution research international 2023-02, Vol.30 (9), p.24398-24407
• Main Authors: Afzal, Muhammad Zaheer, Hameed, Salma, Mohiuddin, Muhammad, Abbasi, Asim
• Format: Article
• Language: English
• Subjects: Adsorption; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Chitosan; Ciprofloxacin; Earth and Environmental Science; Ecotoxicology; Enrofloxacin; Environment; Environmental Chemistry; Environmental Health; Fluoroquinolones - analysis; Humic Substances; Hydrogels; Hydrogen-Ion Concentration; Kinetics; Norfloxacin; Research Article; Waste Water Technology; Water; Water Management; Water Pollutants, Chemical - analysis; Water Pollution Control
• ISSN: 1614-7499; 1614-7499
• DOI: 10.1007/s11356-022-23855-3

This study elaborates the simultaneous removal of three different fluoroquinolones (FQs), i.e., Norfloxacin (NOR), Lomefloxacin (LOM), and Enrofloxacin (ENR) from water using hydrogel beads of humic acid coated biochar (HA-BC) and chitosan. In our previous study, this adsorbent has already achieved tremendous results for the removal of a single FQ, i.e., ciprofloxacin. Now, initial concentrations of all FQs were set 100 mg/L each, and the maximum adsorbed amounts were 38.08 mg/g (NOR), 25.03 mg/g (LOM), and 29.72 mg/g (ENR). Adsorption attained equilibrium after 24 h, which obeyed the pseudo-second-order kinetic model. The mutation of humic acid-biochar/chitosan hydrogel beads (HBCB) with alcoholic solvents, i.e., methanol and ethanol to replace water decreased its sorption capacities from 38.08 mg/g (NOR) to 34.91 mg/g and 32.19 mg/g, respectively. Similarly, from 25.03 mg/g (LOM) to 22.81 mg/g and 19.91 mg/g, and 29.72 mg/g (ENR) to 26.52 mg/g and 24.64 mg/g. Adsorption isotherm data for all FQs were up to both Langmuir and Freundlich, but it suited more to that of Langmuir adsorption isotherm model. Sorption capacities, for all FQs, had a minor decline due to addition of NaCl, NaNO 3 , and Na 2 SO 4 . However, there was a huge decline when Na 3 PO 4 was added into the adsorption system. Adsorbent was desorbed and regenerated for consecutive removal, and it showed good adsorption in the 4 th cycle, i.e., 47 mg/g net adsorption. These results prove that HBCB is not only effective for adsorption removal of ciprofloxacin but also for other FQs too. Graphical Abstract