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oai:figshare.com:article/34021773 2026-09-29T07:07:41Z category_1 category_146 category_21 category_272 category_873 category_39 category_128 category_133 portal_63 item_type_6 month_year_09_2026

Adsorption of Levofloxacin onto Chitosan- and Layered Double Hydroxide-Functionalized Montmorillonite Preyangkar Kundu (25135851) Masahito Yoshimura (24241709) Tomohito Kameda (1482448) Biophysics Space Science Biotechnology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Ecology Hematology Plant Biology various environmental media tested temperatures regardless nontarget aquatic organisms major environmental concern layered double hydroxide langmuir model fitted key operational parameters 30 mg l initial lvx concentration 53 mg g maximum adsorption capacity whole ph range cationic lvx molecules lvx adsorption performance generation fluoroquinolone antibiotic principal adsorption phenomenon including solution ph lvx adsorption efficiency anionic clay ldh mmt composite maintained 0 %) across levofloxacin onto chitosan 1 g throughout 01 g dosage lvx solution cationic lvx 01 g lvx ), removal efficiency principal mechanism 05 g surface adsorption adsorption behavior ph 3 ∼ 90 ∼ 87 ∼ 78 water resources removal efficiencies isoelectric point heterogeneous intercalation electrostatic attraction direct toxicity contaminated waters contact time cation exchange batch experiments antimicrobial resistance amr ). Antibiotic contamination of water resources is a major environmental concern. Beyond their direct toxicity to nontarget aquatic organisms, antibiotic-contaminated waters can serve as reservoirs for the development of antimicrobial resistance (AMR). Levofloxacin (LVX), a third-generation fluoroquinolone antibiotic, has frequently been detected in various environmental media. In this study, the LVX adsorption performance of chitosan/montmorillonite (CTS/MMT) and CO₃-type MgAl layered double hydroxide/montmorillonite (LDH/MMT) composites was evaluated in batch experiments. MMT, a naturally occurring phyllosilicate clay, was functionalized with either the polysaccharide CTS or the anionic clay LDH. The synthesized CTS/MMT composite maintained a negative surface charge across the whole pH range from 2.0 to 12.0, whereas LDH/MMT exhibited an isoelectric point (IEP) at pH 5.1. Key operational parameters, including solution pH, contact time, temperature, and initial LVX concentration, were then optimized. Both adsorbents showed maximum adsorption at pH 3 in a 30 mg L^–1 LVX solution after 60 min, with removal efficiencies of 77.7% and 99.1% for 0.01 g of LDH/MMT and CTS/MMT, respectively. Temperature variation data showed that LVX adsorption efficiency for LDH/MMT remained largely unaffected, ∼78.0% for a 0.01 g dosage, ∼90.0% for 0.05 g, and ∼87.0% for 0.1 g throughout the temperature range 15–35 °C. In contrast, CTS/MMT consistently achieved near-complete LVX removal (∼100.0%) across all tested temperatures regardless of dosage. For 0.01 g of adsorbent dosage, CTS/MMT adsorbed >99.0% LVX within 60 min, whereas adsorption onto LDH/MMT achieved equilibrium within 10 min with 77.1% removal efficiency. The Langmuir model fitted the CTS/MMT adsorption data well, with a maximum adsorption capacity of 107.53 mg g^–1, whereas the Freundlich model better described the adsorption behavior of LDH/MMT. For CTS/MMT, at pH < 5.59, surface adsorption through electrostatic attraction between cationic LVX and the negatively charged composite surface, coupled with cation exchange into the MMT interlayer, may be the principal adsorption phenomenon. On the other hand, heterogeneous intercalation of cationic LVX molecules into the MMT interlayer was the principal mechanism for LVX adsorption onto LDH/MMT. 2026-09-29T00:00:00Z Text Journal contribution 10.1021/acsomega.6c08278.s001 https://figshare.com/articles/journal_contribution/Adsorption_of_Levofloxacin_onto_Chitosan-_and_Layered_Double_Hydroxide-Functionalized_Montmorillonite/34021773 CC BY-NC 4.0