Efficient sonochemical catalytic degradation of tetracycline using TiO2 fractured nanoshells

Efficient removal of tetracycline and norfloxacin contaminants in wastewater onto N-dopped Cu/Al@Biochar as low-cost sorbent: kinetic and adsorption mechanism investigation

In the present study, an adsorbent material (N-dopped Cu/Al@Biochar) was synthesized by integrating N, Cu, and Al atoms into the structure of a biochar. This material was characterized by several physicochemical methods, then applied to the elimination of tetracycline (TC) and norfloxacin (NC). The results obtained showed that the modification method used, although significantly altering the mesoporous structure of the original biochar, generates several functional groups on the surface of the material, giving it excellent adsorption properties. These properties were evaluated by studying the influence of various experimental parameters such as the pH of the solution, the mass of doped biochar, and the contact time on the amount of antibiotic adsorbed. Adsorption studies revealed maximum amounts of TC and NC adsorbed of 65 and 96 mg/g at pH = 8 and 6 respectively with 50 mg of adsorbent for an equilibrium time of 90 min for TC and 60 min for NC at a concentration of 15 mg/L for both antibiotics. This adsorption capacity led to the removal percentages of up to 90 and 82% for TC and NC, respectively. After five cycles of use, a decrease in adsorption efficiency of 9% for TC and 11% for NC was observed, demonstrating the impressive stability of the synthesized material. Kinetic studies revealed that the Elovich and pseudo nth order models are the most appropriate to describe the adsorption kinetics of TC and NC respectively. In addition, the two- and three-parameter isotherm models used in this study revealed multilayer adsorption processes, based on both π - π , n - π , van der Waals bond formation and hydrogen bonds.

Fabrication of S-scheme 0D/3D CeO2QDs/Bi2MoO6 micro-sphere heterostructures for tetracycline degradation from actual pharmaceutical wastewater

The construction of visible-light driven heterojunction has been granted as a promising strategy for designing highly effective photocatalysts with potential application in environmental contaminants removal. In this work, CeO2QDs/Bi2MoO6 (CQBM) heterojunctions were successfully fabricated by combination of the hydrothermal and calcination methods. The optical and electronic properties, chemical compositions, morphology of so-synthesized samples were investigated by various techniques. The optimized CQBM-15% photocatalyst exhibited significantly improved photocatalytic capability for tetracycline hydrochloride (TC-HCl) degradation in different aqueous solution under visible light irradiation. CQBM-15% could degrade 91.2% of TC-HCl from deionized water, while pure CeO2 and Bi2MoO6 could only degrade 38.6% and 50.0%, respectively. After 5 recycles, the degradation efficiency for TC-HCl still could reach 82.6%, indicating its excellent photostability. Additionally, 71.9% of TC-HCl from actual pharmaceutical wastewater (collected from Xi'an C.P. Pharmaceutical Co., Ltd.) was degraded in CQBM-15% system, suggesting its potential practical utilization in tackling actual pharmaceutical wastewater pollution. Detailed experimental results and DFT calculation approved that the tremendously improved photocatalytic capability can attribute to the formation of heterojunction between CeO2QDs and Bi2MoO6, which remarkably increased visible-light response capability, facilitated photo-induced charge carrier separation and migration efficiency with S-scheme charge transfer mechanism. This work provided the guidance to fabricate Bi2MoO6-based heterojunction with promising prospect for the efficient elimination of antibiotic residues from wastewater.