RESUMO
Finding a low cost and effective alternative to noble metal based catalyst has long been concerned in wastewater treatment and organic transformation. This work developed a highly efficient sewage sludge-based catalyst via a simple one-step pyrolysis method, and for the first time, applied it in the catalytic reduction of nitrophenols. Due to the higher content of graphitic nitrogen, abundant defect sites and low electron transfer resistance, sewage sludge derived biochar obtained at 800 °C (SSBC-800) exhibits the best catalytic performance, with the reaction rate of 0.48 min-1 and turnover frequency for 4-nitrophenol calculated to be 1.25 × 10-4 mmolâ¢mg-1 min-1, which is comparable to or even superior than some reported noble metal-based catalyst. Moreover, SSBC-800 showed good recyclability of 90% 4-nitrophenol removal within 8 min after 4 runs, and maintained high catalytic activity in reduction of other substituent nitrophenols, such as 2-nitrophenol (0.54 min-1), 3-nitrophenol (0.61 min-1) and 2,4-dinitrophenol (0.18 min-1), and in real water samples, indicating its practical applicability. The electron paramagnetic resonance spectra and electrochemical characterization demonstrate that SSBC-800 accelerates the dissociation of BH4- to form active hydrogen, which is the main species responsible for 4-nitrophenol reduction, while electron transfer reaction involving the surface bound hydride derived from the intimate contact between BH4- and SSBC-800 plays an important role in this process. This research not only provides a novel valorization pathway for sewage sludge, but also sheds new light on further designing of carbon-based catalyst for nitrophenol reduction.
Assuntos
Carvão Vegetal , Esgotos , Hidrogenação , NitrofenóisRESUMO
Peripheral arterial disease (PAD) can impair healing of diabetic foot (DF) in patients with diabetes mellitus. To determine whether carotid intima-media thickness (CIMT) can predict lower limb arterial lesions in patients with DF, this cross-sectional study enrolled patients with DF at West China Hospital (China) between January 2012 and December 2015. Ultrasonography was used to measure CIMT, assess the internal carotid arteries (ICA) for plaques, and evaluate lower limb segmental arteries for stenosis. The optimal CIMT cutoff for detecting lower limb PAD was determined by receiver operating characteristic (ROC) curve analysis. Factors associated with PAD were identified by logistic regression analyses. A total of 167 patients (mean age: 69.7±10.3 years; 102 men) were included. Patients with PAD were older and had higher levels of total cholesterol and low-density lipoprotein than patients without PAD (P<0.05). The area under the ROC curve was 0.747 (P<0.001). At the optimal CIMT cutoff of 0.71 mm, the sensitivity, specificity, positive predictive value, and negative predictive value were 79.65, 61.11, 81.08, and 58.93%, respectively. Compared with those without PAD, more patients with PAD had CIMT ≥0.71 mm (79.65 vs 38.89%; P<0.001) and ICA plaques (66.37vs 11.11%; P<0.001). Multivariate logistic regression revealed that age (odds ratio [OR]: 1.118; 95% confidence interval [95%CI]: 1.056-1.183; P<0.001), ICA plaques (OR: 13.452; 95%CI: 4.450-40.662; P<0.001), and CIMT ≥0.71 mm (OR: 2.802; 95%CI: 1.092-7.188; P=0.032) were associated with PAD.CIMT may be a surrogate marker of PAD in patients with DF.
Assuntos
Doenças das Artérias Carótidas/complicações , Espessura Intima-Media Carotídea/efeitos adversos , Pé Diabético/etiologia , Extremidade Inferior/irrigação sanguínea , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças das Artérias Carótidas/diagnóstico por imagem , Doenças das Artérias Carótidas/patologia , Estudos Transversais , Feminino , Humanos , Extremidade Inferior/patologia , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos ProspectivosRESUMO
Peripheral arterial disease (PAD) can impair healing of diabetic foot (DF) in patients with diabetes mellitus. To determine whether carotid intima-media thickness (CIMT) can predict lower limb arterial lesions in patients with DF, this cross-sectional study enrolled patients with DF at West China Hospital (China) between January 2012 and December 2015. Ultrasonography was used to measure CIMT, assess the internal carotid arteries (ICA) for plaques, and evaluate lower limb segmental arteries for stenosis. The optimal CIMT cutoff for detecting lower limb PAD was determined by receiver operating characteristic (ROC) curve analysis. Factors associated with PAD were identified by logistic regression analyses. A total of 167 patients (mean age: 69.7±10.3 years; 102 men) were included. Patients with PAD were older and had higher levels of total cholesterol and low-density lipoprotein than patients without PAD (P<0.05). The area under the ROC curve was 0.747 (P<0.001). At the optimal CIMT cutoff of 0.71 mm, the sensitivity, specificity, positive predictive value, and negative predictive value were 79.65, 61.11, 81.08, and 58.93%, respectively. Compared with those without PAD, more patients with PAD had CIMT ≥0.71 mm (79.65 vs 38.89%; P<0.001) and ICA plaques (66.37vs 11.11%; P<0.001). Multivariate logistic regression revealed that age (odds ratio [OR]: 1.118; 95% confidence interval [95%CI]: 1.056-1.183; P<0.001), ICA plaques (OR: 13.452; 95%CI: 4.450-40.662; P<0.001), and CIMT ≥0.71 mm (OR: 2.802; 95%CI: 1.092-7.188; P=0.032) were associated with PAD.CIMT may be a surrogate marker of PAD in patients with DF.