Adsorption kinetics of ciprofloxacin and ofloxacin by green-modified carbon nanotubes

Green synthesis of carbon nanotubes functionalized with iron nanoparticles and coffee husk biomass for efficient removal of losartan and diclofenac: Adsorption kinetics and ANN modeling studies

The presence of emerging contaminants in wastewater poses a global environmental challenge, requiring the development of innovative materials or methods for their treatment. This study focused on the production of green functionalized carbon nanotubes (CNTs) and using them in the adsorption of the pharmaceuticals Losartan (LOS) and Diclofenac (DIC). The efficiency of the methodology was verified by characterization techniques. Elemental composition analysis indicated a significant increase in the iron content after the green functionalization, proving the effectiveness of the method. Thermogravimetric analysis showed similar thermal degradation profiles for pristine CNTs and functionalized CNTs, indicating better post-functionalization thermal stability. BET analysis revealed mesoporous characteristics of CNTs, with increased surface area and pore volumes after functionalization. X-Ray diffraction confirmed the preservation of the lattice structure of the CNTs post-functionalization and post-adsorption, with changes in peak broadening suggesting surface modifications. LOS and DIC adsorption were evaluated via kinetic studies at four different concentrations (0.1-0.4 mmol/L) that were best represented by the pseudo-second order model, suggesting chemisorption mechanisms, with faster and higher uptakes for DIC (0.084-0.261 mmol/g; teq = 5 min) when compared to LOS (0.058-0.235 mmol/g; teq = 20 min). The curves were also studied via artificial neural networks (ANN) and revealed that the best ANN architecture for representing the experimental data is a network with [3 5 5 2] neurons trained using the Bayesian-Regularization algorithm and the Log-sigmoid (hidden layers) and Linear (output layer) transfer functions. The desorption study showed that CaCl2 had better performance in CNT regeneration, reaching its removal capacity above 50% up to 3 cycles, for both pharmaceuticals. These findings reveal the potential of the developed material as a promising adsorbent for targeted removal of pollutants, contributing to advances in the remediation of emerging contaminants and the application of artificial intelligence in adsorption research.

Enhanced degradation and removal of ciprofloxacin and ofloxacin through advanced oxidation and adsorption processes using environmentally friendly modified carbon nanotubes

This study explores the utilization of adsorption and advanced oxidation processes for the degradation of ofloxacin (OFL) and ciprofloxacin (CIP) using a green functionalized carbon nanotube (MWCNT-OH/COOH-E) as adsorbent and catalyst material. The stability and catalytic activity of the solid material were proved by FT-IR and TG/DTG, which also helped to elucidate the reaction mechanisms. In adsorption kinetic studies, both antibiotics showed similar behavior, with an equilibrium at 30 min and 60% removal. The adsorption kinetic data of both antibiotics were well described by the pseudo-first-order (PFO) model. Different advanced oxidation processes (AOPs) were used, and the photolytic degradation was not satisfactory, whereas heterogeneous photocatalysis showed high degradation (⁓ 70%), both processes with 30 min of reaction. Nevertheless, ozonation and catalytic ozonation have resulted in the highest efficiencies, 90%, and 70%, respectively, after 30-min reaction. For AOP data modeling, the first-order model better described CIP and OFL in photocatalytic and ozonation process. Intermediates were detected by MS-MS analysis, such as P313, P330, and P277 for ciprofloxacin and P391 and P332 for ofloxacin. The toxicity test demonstrated that a lower acute toxicity was observed for the photocatalysis method samples, with only 3.1 and 1.5 TU for CIP and OFL, respectively, thus being a promising method for its degradation, due to its lower risk of inducing the proliferation of bacterial resistance in an aquatic environment. Ultimately, the analysis of MWCNT reusability showed good performance for 2 cycles and regeneration of MWCNT with ozone confirmed its effectiveness up to 3 cycles.

Highly efficient activation of peroxymonosulfate by ZIF-67 anchored cotton derived for ciprofloxacin degradation

Metal-organic framework (MOF) and MOF-derived materials have attracted extensive research interest as environmental catalysts. In this study, a composite material (ZIF-67/CCot-8) was successfully prepared using cotton fiber as a substrate and growing ZIF-67 in situ. This material exhibited excellent catalytic performance and significantly improved the efficiency of antibiotics degradation. ZIF-67/CCot-8 at a concentration of 0.05 g/L, combined with 0.2 mM peroxymonosulfate (PMS), removed approximately 97% of ciprofloxacin (CIP) and 99% of tetracycline and sulfamethoxazole within 15 min. The high catalytic efficiency of this catalyst is mainly attributed to the uniform distribution of ZIF-67-derived nanoparticles on the surface of the cotton fibers, providing abundant active sites and thereby significantly enhancing the efficiency of antibiotics degradation. Radical quenching experiments and electron paramagnetic resonance (EPR) analyses revealed that sulfate radicals (SO4•-) and singlet oxygen (1O2) were the main active species. Mass spectrometry (MS) was used to elucidate the CIP degradation pathway. The growth of the roots and stems of soybean sprouts in different water environments (tap water, treated water, and untreated water) was also observed. The results demonstrated a significant improvement in the inhibition of plant growth in the post-degradation CIP solution, indicating a substantial reduction in the toxicity of the degraded aqueous solution. To validate the practicality of the ZIF-67/CCot-8/PMS system, a continuous-flow water-treatment device was designed. This system removed 98% of the CIP solution within 180 min, demonstrating its excellent durability. This study presents a potential pathway for effective antibiotics removal using MOF-derived materials.