The elimination of lead(II) ions in a solution by bio-adsorption: Kinetics, equilibrium, and thermodynamics

In the present study, the removal capacity of Pb(II) ions was investigated using the biomass of dried cattle manure in an aqueous solution. The biomaterials were characterized using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) techniques. The results reveal that the adsorption mechanism may be associated with the interaction between Pb(II) ions and functional groups through aggregation, coordination, ion exchange, microprecipitation, oxidation, and hydrophobicity. The bio-adsorption of the metal was analysed in discontinuous tests; the effect of temperature, pH, agitation, and adsorbent dose was evaluated. The maximum adsorption capacity was determined at pH 7.5, 18°C and 200 rpm. The bio-adsorption of Pb(II) was best fitted to the pseudo-second order model. The experimental data of the isotherm were adjusted to the models of Langmuir, Freundlich and Dubinin-Radushkevich; while Langmuir’s model related better to the experimental data forming a single layer at saturation. The rate of adsorption was rapid, reaching equilibrium after 25 min and removal of 96.8%. Thermodynamic parameters determined that the process was viable, spontaneous, and exothermic. The present study contributes mainly to demonstrating that a biomaterial prepared from bovine manure is a promising adsorbent for heavy metals such as Pb(II). It also reduces the environmental impact of this waste through the generation of greenhouse gases in countries that maintain intensive livestock. Another important aspect is the reduction of the micro- and macronutrients accumulation in soil and contamination of surface waters and aquifers by runoff and seepage during rainy periods

Potential Use of Residual Sawdust of Eucalyptus globulus Labill in Pb (II) Adsorption: Modelling of the Kinetics and Equilibrium

The raw sawdust of Eucalyptusglobulus Labill was studied as an alternative of residual biomaterial for the adsorption of lead (II) in wastewater, evaluating the effect of pH (3, 4, 5, and 6) in a batch system. From the characterization of the biomaterial, it was found that the biomass has a low ash content, and from the scanning electron microscopy (SEM) microphotographs that it presents a porous morphology with diverse texture and presence of fiber fragments, which describe the heterogeneity of the material. The Fourier transform infrared (FTIR) spectrum showed the presence of functional groups of NHR, OH, COOH, and hydrocarbons, which are part of the structure of lignin, cellulose, hemicellulose, and pectin. From the adsorption experiments, it was obtained that the optimal value of pH 6, reaching a removal percentage of 96% and an adsorption capacity of 4.80 mg/g. The model that better adjusted the kinetics results was the pseudo-second-order model and the Langmuir and Freundlich isothermal models described the adsorption equilibrium; it was found that in the system prevails chemisorption, supported in ion exchange by Pb (II) and the biomass’ functional groups. From the results, eucalyptus sawdust is suggested as a low-cost adsorbent for Pb (II) bioadsorption present in solution

Gender differences and management of stroke risk of nonvalvular atrial fibrillation in an upper middle-income country: Insights from the CARMEN-AF registry

Background: Atrial Fibrillation (AF) is associated with an increased risk of stroke and systemic embolism. Several studies have suggested that female AF patients could have a greater risk for stroke. There is scarce information about clinical characteristics and use of antithrombotic therapies in Latin American patients with nonvalvular AF. Objective: To describe the gender differences in clinical characteristics, thromboembolic risk, and antithrombotic therapy of patients with nonvalvular AF recruited in Mexico, an upper middle-income country, into the prospective national CARMEN-AF Registry. Methods: A total of 1423 consecutive patients, with at least one thromboembolic risk factor were enrolled in CARMEN-AF Registry during a three-year period (2014–2017). They were categorized according to Gender. Results: Overall, 48.6% were women, mean age 70 ± 12 years. Diabetes, smoking, alcoholism, non-ischemic cardiomyopathy, coronary artery disease, and obstructive sleep apnea were higher in men. Most women were found with paroxysmal AF (40.6%), and most men with permanent AF (44.0%). No gender differences were found in the use of vitamin K antagonists (VKA) (30.5% in women vs. 28.0% in men). No gender differences were found in the use of direct oral anticoagulants (DOAC) (33.8% women vs 35.4% men). Conclusions: CARMEN-AF Registry demonstrates that in Mexico, regardless of gender, a large proportion of patients remain undertreated. No gender differences were found in the use of VKA or DOAC. Keywords: Atrial fibrillation, Gender, Thromboembolic risk, Antithrombotic therapy, Stroke, Mexic