Machine learning for the adsorptive removal of ciprofloxacin using sugarcane bagasse as a low-cost biosorbent: comparison of analytic, mechanistic, and neural network modeling.

Contamination with traces of pharmaceutical compounds, such as ciprofloxacin, has prompted interest in their removal via low-cost, efficient biomass-based adsorption. In this study, classical models, a mechanistic model, and a neural network model were evaluated for predicting ciprofloxacin breakthrough curves in both laboratory- and pilot scales. For the laboratory-scale (d = 2.2 cm, Co = 5 mg/L, Q = 7 mL/min, T = 18 °C) and pilot-scale (D = 4.4 cm, Co = 5 mg/L, Q = 28 mL/min, T = 18 °C) setups, the experimental adsorption capacities were 2.19 and 2.53 mg/g, respectively. The mechanistic model reproduced the breakthrough data with high accuracy on both scales (R2 > 0.4 and X2 < 0.15), and its fit was higher than conventional analytical models, namely the Clark, Modified Dose-Response, and Bohart-Adams models. The neural network model showed the highest level of agreement between predicted and experimental data with values of R2 = 0.993, X2 = 0.0032 (pilot-scale) and R2 = 0.986, X2 = 0.0022 (laboratory-scale). This study demonstrates that machine learning algorithms exhibit great potential for predicting the liquid adsorption of emerging pollutants in fixed bed.

Antibacterial and Antifungal Properties of Electrospun Recycled PET Polymeric Fibers Functionalized with Zinc Oxide Nanoparticles.

Currently, to reduce the environmental problems associated with plastic waste, methods are being sought to use this waste as raw materials in different applications, such as fibers. In addition, to improve these materials and provide different properties, nanoparticles (NPs) are incorporated. In the present work, polymeric fibers made of recycled polyethylene terephthalate (r-PET) from post-consumer water bottles, functionalized with 0%, 1.5%, 3% and 6% zinc oxide nanoparticles (ZnO-NPs) in function of r-PET weight, were elaborated to evaluate their antibacterial and antifungal characteristics. The ZnO-NPs were synthesized by the solvothermal method, obtaining particles with a mean diameter of 38.15 nm, while the fibers were obtained by electrospinning with a diameter range between 200-5000 nm. The functionalized fibers were carried out against Escherichia coli and Bacillus subtilis through the agar diffusion method, obtaining the highest inhibition halo at 6% w/w ZnO-NPs, being 26.5 mm and 34.25 mm, respectively. In addition, the same method was used to evaluate the antifungal activity of Penicillium s.p. and Fusarium graminearum, observing antifungal properties due to the presence of nanoparticles in the fibers.

Mathematical modeling and numerical simulation of sulfamethoxazole adsorption onto sugarcane bagasse in a fixed-bed column.

Having rigorous mathematical models is essential for the design and scaling of adsorption columns. In this study, the dynamic behavior of the sulfamethoxazole adsorption on sugarcane bagasse was studied and compared using analytical models and a theoretical mechanistic model. Initially, fixed-bed column tests were carried out at different flow rates and bed heights. Then, the experimental data were fitted with the most widely used analytical kinetic models, and their fit and fixed-bed parameters were compared with the mechanistic model. Of all analytical models analyzed, the Log-Gompertz model was the one that had the best agreed with experimental data. Although some analytical models fitted the experimental data accurately, their usefulness was questionable. Their parameters did not show a clear relationship with the change in operating conditions, and in certain cases had different behavior from that observed in experimentation. Conversely, the mechanistic model not only predicted the breakthrough curves with great accuracy in the initial and transition stage (R2 > 0.92; SSE < 0.06), but it also estimated relevant parameters. Additionally, the effects of the global mass transfer coefficient (Ki) and the axial dispersion coefficient (Dz) on breakthrough curves were studied using the mechanistic model. Increasing Ki increased the slope of the breakthrough curves with a faster adsorption rate. Similarly, high values of Dz produced lower adsorption capacities of the adsorbent; and it was established that the axial dispersion is relevant in SMX adsorption on SB. The theoretical model presented can be used for the design, scaling, and optimization of adsorption columns.

[Levonorgestrel intrauterine device associated with ureterpyelocaliceal ectasia]. / Dispositivo intrauterino con levonorgestrel translocado asociado con ectasia ureteropielocalicial bilateral.

BACKGROUND: In 2010, Health Canada, the equivalent to the FDA, reported that the risk of uterine perforation caused by levonorgestrel intrauterine device (IUD) is very serious, warning that its use had increased the number of uterine perforation. CLINICAL CASE: A 33 years old patient in who was placed three years before a levonorgestrel IUD; She presented evolution of 10 days with pain in hypogastric and both flanks and chronic constipation of two years; in exploration: moderate abdominal distention, IUD strings were not visible in uterine cervix. With translocated IUD diagnosis, a tomography was performed, finding IUD in abdominal cavity and ureter pyelocalyceal bilateral ectasia; preoperative plasma concentration of levonorgestrel 5.1 nmol/L, leukocytosis of 11,000 cells/mm3, and 20-30 erythrocytes in urine exam. Laparoscopic resection of omentum attached to IUD translocated was performed. One month after surgery plasma levonorgestrel in 0.3 nmol/L, normal urinalysis and hematic cytometry and resolution of the urinary tract ectasia. CONCLUSIONS: devices translocated with levonorgestrel, must be removed because the inflammatory reaction caused and the perforation of hollow viscera likelihood, with possibility to produce digestive tract and urinary tract ectasia by its pharmacologic action on smooth muscle.