Renewable Tb/Eu-Loaded Garlic Peels for Enhanced Adsorption of Enrofloxacin: Kinetics, Isotherms, Thermodynamics, and Mechanism

Abstract

Environmentally friendly terbium, europium, and terbium/europium-loaded garlic peels (Tb@GP, Eu@GP, and Tb/Eu@GP) were successfully synthesized and evaluated as biosorbents for the extraction of enrofloxacin (ENR) from aqueous solutions. Notably, it was found that the adsorption capacity of Tb/Eu@GP (769 mg g −1 ) for enrofloxacin was significantly enhanced compared with unloaded GP (29.8 mg g −1 ) and was superior over Tb@GP (580 mg g −1 ) and Eu@ GP (421 mg g −1 ). The high adsorption capacity of Tb/Eu@ GP reflected the efficiency and cost effectiveness of the adsorption process. In order to gain insight into the modification method and adsorption behaviors, Tb@GP, Eu@GP, and Tb/Eu@GP were fully characterized, and their adsorption kinetics, isotherms, and thermodynamics were investigated. Additionally, Tb/Eu@GP was found to be highly efficient at pH values ranging from 6.0 to 8.0. Besides, ultrapure water containing 5% ammonia could elute 98.1 ± 1.5% of the absorbed ENR from Tb/Eu@GP, and the reusability and regeneration test also revealed the sustainability of Tb/Eu@GP. Moreover, XPS analysis confirmed ligand exchange between the hydroxyl and the fluorine group of enrofloxacin might be the main mechanism in the adsorption process. This work demonstrated loading terbium and europium on agricultural byproduct could be a potential method for developing costeffective and eco-friendly biosorbents for fluoroquinolones.

A Biodegradable Magnetic Nanocomposite as a Superabsorbent for the Simultaneous Removal of Selected Fluoroquinolones from Environmental Water Matrices: Isotherm, Kinetics, Thermodynamic Studies and Cost Analysis

“…These could be attributed to electrostatic repulsion between negatively charged FQs and negatively charged nanocomposite. Several researchers in the literature have observed similar findings with respect to the adsorption behavior of FQs at low and high pH values [61,[65][66][67][68][69][70][71]73,74]. The results for the effect of sonication power level are shown in Figure 5B,C; it was not significant at the 95% confidence level.…”

“…Below and above these values, a decrease in analytical response was observed. This is because DANO, ENDRO and LEVO can exist in three forms in aqueous systems, that is, cationic (pH > pK a2 ), zwitterionic (pKa1 ≤ pH ≤ pK a2 ) and anionic (pH < pK a1 ), and these forms are pH-dependent [65][66][67][68]. Consequently, the adsorption mechanism is also dependent on the adsorbent surface charge.…”

“…Consequently, the adsorption mechanism is also dependent on the adsorbent surface charge. For instance, the FQ antibiotics can be adsorbed by a negatively or positively charged adsorbent using cation exchange through protonation of amine group or electrostatic interaction due to the deprotonation of carboxylic groups [39,61,[65][66][67][69][70][71][72].…”

“…The data were analysed using three commonly used kinetic models; namely, pseudo-first-order, pseudo-second-order and intraparticle diffusion. The equations of these kinetic models are widely reported (See Table 1), and they were adapted from the literature [66,67,69]. The estimated parameters are presented in Table 4.…”

Impact of NaOH- surface treatment on emerging pollutant biosorption performance using marine algua, Posidonia Oceanica

“…The progressive coverage of active sites owing to intraparticle diffusion of AMX onto PO and Na-PO is exhibited by the next step. The rate diminution in the intraparticle diffusion as a consequence to weak adsorbate concentration and lesser accessibility of active sites is reported by the last stage (Zhao et al, 2018).…”