Kinetic studies of adsorption of Fe(III) from aqueous solution by untreated and alkali-treated rice straw

Modifications of rice straws surfaces by sodium hydroxide (NaOH) were carried out in order to study the effects of this on the surface functional groups properties. Comparison was made between untreated and alkali-treated rice straws on the removal of Fe(III) from aqueous solution. In this study, four characterizations of raw rice straw have been conducted. The morphological characteristics by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Analysis (EDXA)the functional group present in the rice straw by Fourier Transform Infrared (FTIR) spectroscopy and the X-ray Diffraction (XRD). The result of Scanning Electron Microscopy (SEM) also shows that rice straw is a porous material. Rice straw contains on –OH functional group that can bind with metal ions. To be able to enhance the sorption capacity of rice straw in metals, removing from waste water, alkali treatment should be done. This shows that rice straw can be used as adsorbent for ferric ions removing from wastewater.The effect of pH, sorption kinetics and isotherms were studied in batch experiments. The good correlation coefficient was obtained from pseudo second-order kinetic model, which agreed with conception as the rate-limiting mechanism. Sorption isotherm test showed that equilibrium sorption data were better represented by Temkin model. The highly efficient, low cost and the rapid uptake of Fe(III) by untreated (RS) in comparison with alkali-treated (MRS) rice straws, indicated that it could be an excellent alternative for the removal of ferric ions by sorption process

Elevation of D-dimer levels are associated with early need for mechanical ventilation support in patients with COVID-19

Abstract Background Severe COVID-19 disease is typically associated with an urgent need for supplemental oxygen therapy that may be successfully delivered through conventional methods or require invasive mechanical ventilation. Early prediction of the need for invasive mechanical ventilation could significantly improve outcomes of COVID-19 patients. Plasma levels of D-dimer and a number of inflammatory markers as well as values of complete blood counts, all measured in the first two days of hospital admission of COVID-19 patients, were evaluated for their significance as predictors of the eventual need for invasive mechanical ventilation support as well as their values as predictors of post-ventilation morbidly and mortality. Methods This retrospective cohort study was conducted at a single center and included data pertaining to 200 patients with previously confirmed moderate to severe COVID-19 disease in the period between May 2021 and the end of December 2022. Data were retrieved from medical records for further analysis. Results The mean (SD) age of patients stood at 59 (14) years of age, and with a majority of patients being male (77%). About 18% of cases, all of significantly older age, had been connected to invasive mechanical ventilation (IMV). Total leucocytic count (TLC), as well as levels of urea, creatinine, D-dimer, ferritin, and CRP in IMV patients were significantly higher than non-ventilated patients (p < 0.01 for all). In contrast, lymphocytic count, hemoglobin level, and platelet count were significantly lower in IMV patients (p < 0.001, 0.04, and 0.002, respectively). The mortality rate was significantly higher in IMV patients (p < 0.001). D-dimer independently predicted IMV demand (OR = 1, p = 0.001 in adjusted and unadjusted models). The utility of D-dimer was excellent; and the cutoff level of above 1415 µ/L showed sensitivity and specificity of about 92% and 76%, respectively. Also, the D-dimer level was very effective in predicting post-IMV survival; the AUC = 0.86, p = 0.02, and a cutoff value below 4558 µ/L was associated with 100% and 66% sensitivity and specificity, respectively. Conclusions High D-dimer levels independently correlated with the need for invasive mechanical ventilation. Low levels of this marker could evidently predict post-IMV survival of mechanically ventilated COVID-19 patients. Measuring D-dimer levels during routine follow up of those patients would thus be useful in predicting patient outcomes