Sonochemical degradation of ofloxacin in aqueous solutions

Insight into advanced oxidation processes for the degradation of fluoroquinolone antibiotics: Removal, mechanism, and influencing factors

The enrichment and transport of antibiotics in the environments pose many potential hazards to aquatic animals and humans, which has become one of the public health challenges worldwide. As a widely used class of antibiotics, fluoroquinolones (FQs) generally accumulated in the environments as traditional sewage treatment plants cannot completely remove them. Advanced oxidation processes (AOPs) have been shown to be a promising method for the abatement of antibiotic contamination. In this review, influencing factors and relevant mechanisms of FQs removal by various AOPs were summarized. Compared with other AOPs, photocatalytic ozone may be considered as a cost-effective method for degrading FQs. Finally, the benefits and application restrictions of AOPs were discussed, along with proposed research directions to provide new insights into the control of FQs pollutant via AOPs in practical applications.

Highly Effective Removal of Ofloxacin from Water with Copper-Doped ZIF-8

Residual antibiotics in wastewater have gained widespread attention because of their toxicity to humans and the environment. In this work, Cu-doped ZIF-8s (Cu-ZIF-8s) were successfully synthesized by the impregnation of Cu²⁺ in ZIF-8 and applied in the removal of ofloxacin (OFX) from water. Remarkably, excellent adsorption performance was obtained in Cu-ZIF-8s, especially for Cu-ZIF-8-1, in which the adsorption capacity (599.96 mg·g⁻¹) was 4.2 times higher than that of ZIF-8 and superior to various adsorbents reported previously. The adsorption kinetics and adsorption isotherm follow the pseudo-second-order model and the Langmuir model, respectively. Furthermore, the removal efficiencies of OFX in Cu-ZIF-8-1 reached over 90% at low concentrations. It was revealed that electrostatic interaction and complexation play important roles in the adsorption process. In addition, the material can be regenerated by simple methods. Therefore, the obtained Cu-doped MOFs may have a promising application in the treatment of antibiotic-containing wastewater.

The effect of high hydrostatic pressure on tetracycline hydrochloride and sulfathiazole residues in various food matrices - comparison with ultrasound and heat treatment

Antibiotic residues in food pose serious direct and indirect risks for consumers. The aim of this study was to investigate the effect of High Hydrostatic Pressure (HHP) on tetracycline hydrochloride (TCH) and sulfathiazole (STZ) residues in honey, milk, and water. Three different pressures were tested for their efficiency and treatment at 580 MPa for 6 min was finally selected. Qualitative and quantitative determination of antibiotics were performed with HPLC and LC-MS. HHP treatment was compared to ultrasound and heat treatment. HHP treatment was found to be more effective than the other two methods for both antibiotics in water and milk. The reduction of STZ in honey was over 90%, while no reduction was observed for TCH. The highest TCH reduction was recorded after HHP treatment in water (76.4%) and the highest STZ reduction after ultrasound treatment in honey (94.3%). Reduction of the two antibiotics in different matrices did not follow a similar pattern. For the HHP treatment, the effect of the initial concentration of the two antibiotics was studied under two different storage conditions (refrigerated and frozen storage). The effectiveness of the method was found to be affected by the initial concentration, in both storage conditions for STZ, while for TCH significant differences were observed only for refrigerated storage.

Sonochemical processes for the degradation of antibiotics in aqueous solutions: A review

Antibiotic residues in water are general health and environmental risks due to the antibiotic-resistance phenomenon. Sonication has been included among the advanced oxidation processes (AOPs) used to remove recalcitrant contaminants in aquatic environments. Sonochemical processes have shown substantial advantages, including cleanliness, safety, energy savings and either negligible or no secondary pollution. This review provides a wide overview of the different protocols and degradation mechanisms for antibiotics that either use sonication alone or in hybrid processes, such as sonication with catalysts, Fenton and Fenton-like processes, photolysis, ozonation, etc.

Spiral computed tomography evaluation of rabbit VX2 hepatic tumors treated with 20 kHz ultrasound and microbubbles

The aim of the present study was to explore the therapeutic effect of 20 kHz ultrasound (US) and microbubbles (MBs) on rabbit VX2 liver tumors by spiral computed tomography (CT) scanning. A total of 16 New Zealand rabbits with hepatic VX2 tumors were divided into four groups: Control, MB, low-frequency US and US + MB. The treatment effect was evaluated by spiral CT scanning prior to, during and following treatment (at 0 weeks and the end of 1 and 2 weeks). The tumor growth rate was recorded. The specimens of VX2 tumors were collected for histological examination and transmission electron microscopy (TEM). No significant differences were observed between tumor areas measured by CT and pathology after 2-week treatment (P>0.05). The mean tumor growth rates in the control, MB, US and US + MB groups after 2 weeks of treatment were 385±21, 353±12, 302±14 and 154±9%, respectively (P<0.05, US + MB vs. the other three groups). Hematoxylin and eosin staining in the US + MB group revealed coagulation necrosis, interstitial hemorrhage and intravascular thrombosis. In the control, MB and US groups, tumor cells exhibited clear nuclear hyperchromatism. TEM of US + MB revealed vascular endothelial cell wall rupture, widened endothelial cell gaps, interstitial erythrocyte leakage and microvascular thrombosis, while intact vascular endothelial cells and normal erythrocytes in the tumor vessels were observed in the control, MB and US groups. A combination of 20 kHz US and MBs may effectively inhibit rabbit VX2 tumors. Spiral CT scanning is an ideal method to evaluate the US treatment on rabbit tumors.

Recent advancements in the sonophotocatalysis (SPC) and doped-sonophotocatalysis (DSPC) for the treatment of recalcitrant hazardous organic water pollutants

Sonophotocatalysis (SPC) is considered to be one of the important wastewater treatment techniques and hence attracted the attention of researchers to eliminate recalcitrant hazardous organic pollutants from aqueous phase. In general, SPC refers to the integrated use of ultrasonic sound waves, ultraviolet radiation and the addition of a semiconductor material which functions as a photocatalyst. Current research has brought numerous improvements in the SPC based treatment by opting visible light irradiation, nanocomposite catalysts and numerous catalyst supports for better stability and performance. This review accomplishes a critical analysis with respect to the recent advancements. The efficiency of SPC based treatments has been analyzed by considering the individual methods i.e. sonolysis, photocatalysis, sonophotolysis, sono-ozone, photo-Fenton and sono-Fenton. Besides, the essential parameters such as solution temperature, concentrations of initial pollutant and catalyst, initial pH, dosages of Fenton's reagent and hydrogen peroxide (H₂O₂), ultrasonic power density, gas sparging, addition of radical scavenger, addition of carbon tetrachloride and methanol have been discussed with suggestions for the selection of optimum parameters. A higher synergistic pollutant removal rate has been reported during SPC treatment as compared to individual methods and the implementation of numerous doping materials and supports for the photocatalyst enhances the degradation rate of pollutants using DSPC under both visible and UV irradiation. Overall, SPC and DSPC based wastewater treatments are emerging as potential techniques as they provide effective solution in removing the recalcitrant organic pollutants and progressive research is expected to bring out superior treatment efficiency using these advanced technologies.

IMPORTANCE OF THIS REVIEW

The review has accomplished a thorough and a critical analysis of sonophotocatalysis (SPC) based on the recently published journals. Recent advancements in the doped sonophotocatalysis (DSPC) and the mechanisms behind synergistic enhancement in the pollutant degradation rate have been discussed with justifications. Besides, the possible future works are suggested for the advancements in sonophotocatalysis based treatment. This review will be beneficial for electing a SPC based method because of the accomplished sharp comparisons among the published results. The review includes current advancements of SPC based methods which aid for a low-cost and a large-scale wastewater treatment application.

Synthesis of Fe-doped Bi2O3 nanocatalyst and its sonophotocatalytic activity on synthetic dye and real textile wastewater

The catalysts such as Fe, Bi₂O₃, and Fe-doped Bi₂O₃ were synthesized for the sonophotocatalytic treatment of synthetic dye and real textile wastewater. The resultant catalysts were characterized for its size and uniform shape using x-ray diffractogram (XRD) and scanning electron microscopy (SEM) which signified the nanorod shape formed Bi₂O₃. The higher ultraviolet light absorbance capacity of the catalysts was also evident using diffuse reflectance spectroscopy (DRS). Initially, the effect of conventional parameters such as initial pH, gas bubbling (argon, oxygen, air and nitrogen) and oxidant addition (H₂O₂ and peroxymonosulfate) in the presence of sonolysis (22 and 37 kHz frequency) and photolysis (UV-C light) on 10 ppm Basic Brown 1 dye was studied. The results showed that highest decolorization of 62 % was attained for 3 g/L peroxymonosulfate under 37 kHz frequency sonolysis treatment. Secondly, with the catalyst study, highest of 46 % dye color removal was obtained with 4 g/L Fe under 37 kHz frequency sonolysis treatment. The sonophotocatalytic treatment of dye with Fe-doped Bi₂O₃ catalyst in combination with peroxymonosulfate showed highest color removal of 99 %. Finally, the sonophotocatalytic treatment of real textile wastewater in the presence of 3 g/L Fe-doped Bi₂O₃ and 6 g/L peroxymonosulfate reduced the total organic carbon (TOC) and chemical oxygen demand (COD) level to 77 and 91 %, respectively, in 180 min. The reported treatment process was found to treat the synthetic dye and real textile wastewater effectively.

Submicrometric Iron Particles for the Removal of Pharmaceuticals from Water: Application to b-Lactam Antibiotics

Sub-micrometric iron particles (Fe0) and amended Fe0 (Cu0Fe0) were tested for the aqueous removal of b-lactam antibiotics. Comparative batch experiments were performed separately on aqueous solutions of dicloxacillin (DCX), cloxacillin (CLX) and oxacillin (OXA). Three different initial concentrations (1, 5 and 10 mg L-1) and four different iron loads (r = 10, 20, 40 and 53 g L-1) were tested. Furthermore, two different mixing regimes were tested: (i) non-disturbed conditions, and (ii) vortex mixing. This experimental design enabled the confirmation of the crucial role of in-situ formed iron corrosion products (Fe oxides) on the removal process. The dynamic process of Fe oxides formation induces adsorption and enmeshment (sequestration or co-precipitation) of dissolved antibiotics. Results clearly delineated the superiority of Cu0Fe0 bimetallics compared to Fe0. For example, after 4 h of contact with iron particles at r = 40 g L-1, OXA, CLX and DCX (10 mg L-1 each) disappeared to an extent of 31, 46 and 71%. However, quantitative antibiotic removal (~90%) was noticed when Cu0Fe0 bimetallic was used at lesser load (r = 20 g L-1)under vortex mixing. On the other hand, non-disturbed systems showed partial removal (~ 25%) of antibiotics over 7 h of reaction at r = 10 g L-1 (Fe0) while almost complete removals were noticed for the Cu0Fe0 bimetallic system for the same metal load and period e.g. 75, 79 and 86% removal for OXA, CLX and DCX respectively.