Mechanisms of Individual and Simultaneous Adsorption of Antibiotics and Dyes onto Halloysite Nanoclay and Regeneration of Saturated Adsorbent via Cold Plasma Bubbling

Abstract

Halloysite nanoclay (HNC) was examined as an adsorbent for the individual and simultaneous removal of antibiotic enrofloxacin (ENRO) and methylene blue (MB) from aqueous solutions, alongside its regeneration via cold atmospheric plasma (CAP) bubbling. Initially, batch kinetics and isotherm studies were carried out, while the effect of several parameters was evaluated. Both ENRO and MB adsorption onto HNC was better described by Langmuir model, with its maximum adsorption capacity being 34.80 and 27.66 mg/g, respectively. A Pseudo-second order model fitted the experimental data satisfactorily, suggesting chemisorption (through electrostatic interactions) as the prevailing adsorption mechanism, whereas adsorption was also controlled by film diffusion. In the binary system, the presence of MB seemed to act antagonistically to the adsorption of ENRO. The saturated adsorbent was regenerated inside a CAP microbubble reactor and its adsorption capacity was re-tested by applying new adsorption cycles. CAP bubbling was able to efficiently regenerate saturated HNC with low energy requirements (16.67 Wh/g-adsorbent) in contrast to Fenton oxidation. Most importantly, the enhanced adsorption capacity of the CAP-regenerated HNC (compared to raw HNC), when applied in new adsorption cycles, indicated its activation during the regeneration process. The present study provides a green, sustainable and highly effective alternative for water remediation where pharmaceutical and dyes co-exist.

Removal of Cephalexin-Antibiotic from Drinking Water by Designing CaCl2 Incorporated Chitosan Co- Tragacanth Gum Composite Hydrogel

“…Energy-dispersive X-ray (EDX) analysis corroborated the presence of significant levels of carbon, nitrogen, oxygen, and calcium, with metallic nanoparticles visible in the spectra. This confirmed the composite hydrogel's capacity to bind and potentially load antibiotics, showcasing its utility in purifying water (17)(18)(19)(20).…”

“…The surface morphology was meticulously analyzed using a Field Emission Scanning Electron Microscope (FESEM), revealing a rough and porous texture, ideal for trapping impurities through complexation and hydrogen bonding (17)(18)(19)(20). The freeze-drying preparation of the samples, followed by sputter-gold coating, provided an in-depth examination of the hydrogel's internal structures.…”

“…The freeze-drying preparation of the samples, followed by sputter-gold coating, provided an in-depth examination of the hydrogel's internal structures. The FESEM images showed microgranular structures and nanoparticles, suggesting a large surface area conducive to adsorption (17)(18)(19)(20).…”

Peanut Shell as a Natural Adsorbent for the Removal of Acid Blue 25 from Aqueous Solution

“…This 1indicates that there are other mechanisms that are involved in the adsorption process, which are rate-limiting, in 2 addition to pore diffusion. Along with intraparticle diffusion, another mechanism might be involved during the 3 entire adsorption process(Giannoulia et al, 2023) 4 5 6…”

Nanostructured Materials and Advanced Processes for Application in Water Purification

“…These authors concluded that Ag 3 PO 4 –based materials could be reliably used for the degradation of methyl orange (MO) as they mostly retain their photoactivity during the second recycling test. In the final paper by Giannoulia et al [ 21 ], halloysite nanoclay (HNC) was examined as an adsorbent for the individual and simultaneous removal of antibiotic enrofloxacin (ENRO) and methylene blue (MB) from aqueous solutions, alongside its successful regeneration via cold atmospheric plasma (CAP) bubbling. In addition, CAP bubbling induced chemical modifications on the HNC surface, increasing its adsorption capacity when applied to new adsorption cycles.…”