RESUMEN
Heavy metals are one of the most dangerous and critical threats to human and environment. In this study, the adsorption efficiency of activated carbon from cassava peels considered as agricultural waste (CPR) was evaluated for removal of heavy metals Cr (VI) and Co (II) from aqueous media. Cassava peel carbon (CPC) was obtained by acid treatment. Structural and morphological properties were investigated using Fourier Transform Infra-Red (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmet-Teller surface area (BET) and X-Ray Diffraction (XRD). The adsorption experiments were conducted in batch mode under natural solution pH and complexation of the heavy metals, which allows the use of UV-Visible spectroscopy technique. CPC adsorbent exhibited a high adsorption capacity, according to Langmuir model, for Cr (VI) (166.35 mg/g) and Co (II) (301.63 mg/g) at 25 °C. Kinetic and adsorption isotherms followed the pseudo second-order and Langmuir isotherm models for both metals, respectively. Thermodynamic study confirmed the spontaneity and endothermic nature of both metals adsorption onto CPC surface.
Asunto(s)
Manihot , Contaminantes Químicos del Agua , Adsorción , Carbón Orgánico , Cromo/análisis , Humanos , Concentración de Iones de Hidrógeno , Cinética , Espectroscopía Infrarroja por Transformada de Fourier , Contaminantes Químicos del Agua/análisisRESUMEN
PURPOSE: To assess whether the definition of an IHF used as an exclusion criterion influences the results of trauma center benchmarking. METHODS: We conducted a multicenter retrospective cohort study with data from an integrated Canadian trauma system. The study population included all patients admitted between 1999 and 2010 to any of the 57 adult trauma centers. Seven definitions of IHF based on diagnostic codes, age, mechanism of injury, and secondary injuries, identified in a systematic review, were used. Trauma centers were benchmarked using risk-adjusted mortality estimates generated using the Trauma Risk Adjustment Model. The agreement between benchmarking results generated under different IHF definitions was evaluated with correlation coefficients on adjusted mortality estimates. Correlation coefficients >0.95 were considered to convey acceptable agreement. RESULTS: The study population consisted of 172,872 patients before exclusion of IHF and between 128,094 and 139,588 patients after exclusion. Correlation coefficients between risk-adjusted mortality estimates generated in populations including and excluding IHF varied between 0.86 and 0.90. Correlation coefficients of estimates generated under different definitions of IHF varied between 0.97 and 0.99, even when analyses were restricted to patients aged ≥65 years. CONCLUSIONS: Although the exclusion of patients with IHF has an influence on the results of trauma center benchmarking based on mortality, the definition of IHF in terms of diagnostic codes, age, mechanism of injury and secondary injury has no significant impact on benchmarking results. Results suggest that there is no need to obtain formal consensus on the definition of IHF for benchmarking activities.