Adsorption performance and kinetics of Cr(VI) onto activated carbons derived from the waste leaves of invasive plants Rhus typhina and Amorpha fruticosa.

To maximize the potential of biomass from invasive plants, waste leaves from Rhus typhina (RT) and Amorpha fruticosa (AF) were used to prepare activated carbons (ACs) for the efficient removal of chromium from wastewater. Six ACs were prepared by CO2 activation at 850 °C with varying flow rates (500, 1000, and 1500 mL/min) and characterized by yield, pH, N2 adsorption isotherm, FTIR, SEM, TG, and XPS. The adsorption isotherm and kinetics for chromium removal were analyzed. The outcomes showed that the ACs had mesoporous structures with specific surface areas of 408.05-701.01 m2/g and pore volumes of 0.360-0.653 cm3/g. The pores are distributed among the agglomerated nanoparticles on the surface of the granules. The existence of two kinds of chromium compounds and two valance states, Cr(III) and Cr(VI), in spent ACs was identified by the FTIR and XPS spectra. The Cr (VI) equilibrium data and adsorption kinetics were well-fit with the Langmuir isotherm (R2 = 0.936-0.967) and pseudo-second-order kinetic models (R2 = 0.795-0.937). The maximum Langmuir Cr adsorption capacities of ACRT1.0 and ACAF0.5 were estimated to be 266.54 and 255.21 mg/g at pH = 2.0, respectively. Concentrations of Cr(III) and Cr(VI) in filtrates after equilibrium, combined with XPS and TGA analysis of spent ACs, illustrated that Cr(VI) was converted to the less harmful trivalent chromate Cr(III) during the adsorption processes. Cr(III) and Cr(VI) probably formed compounds with carbon and nitrogen atoms on the surfaces of ACs. ACs with abundant surface N-H groups achieved high Cr adsorption performance. The waste leaves from these invasive plants are suitable for producing cost-effective and efficient ACs for removing Cr (VI) from water by chemical adsorption.

[Correlation between four limbs perfusion index and lactic acid in patients with severe neurological diseases].

OBJECTIVE: To observe the correlation between the four limbs perfusion index (PI) and blood lactic acid in patients with neurosis, and evaluate the predictive value of PI on microcirculation perfusion metabolic disorder in patients with neurosis. METHODS: A prospective observational study was conducted. Adult patients admitted to the department of neurological intensive care unit (NICU) of the First Affiliated Hospital of Xinjiang Medical University from July 1 to August 20 in 2020 were enrolled. Under the condition of indoor temperature controlled at 25 centigrade, all patients were placed in the supine position, and the blood pressure, heart rate, PI of both fingers and thumb toes and arterial blood lactic acid were measured within 24 hours and 24-48 hours after NICU. The difference of four limbs PI at different time periods and its correlation with lactic acid were compared. Receiver operator characteristic curve (ROC curve) was used to evaluate the predictive value of four limbs PI on patients with microcirculatory perfusion metabolic disorder. RESULTS: A total of 44 patients with neurosis were enrolled, including 28 males and 16 females; average age (61.2±16.5) years old. There were no significant differences in PI of the left index finger and the right index finger [2.57 (1.44, 4.79) vs. 2.70 (1.25, 5.33)], PI of the left toe and the right toe [2.09 (0.85, 4.76) vs. 1.88 (0.74, 4.32)] within 24 hours after entering the NICU, and the PI of the left index finger and the right index finger [3.17 (1.49, 5.07) vs. 3.14 (1.33, 5.36)], PI of the left toe and the right toe [2.07 (0.75, 5.20) vs. 2.07 (0.68, 4.67)] at 24-48 hours after NICU admission (all P > 0.05). However, compared to the PI of the upper and lower limbs on the same side, except for the 24-48 hours after ICU of the PI difference between the left index finger and the left toe (P > 0.05), the PI of the toe was lower than that of the index finger at the other time periods (all P < 0.05). The correlation analysis showed that the PI value of four limbs of patients in both time periods were significantly negatively correlated with arterial blood lactic acid (the r values of the left index finger, the right index finger, the left toe and the right toe were -0.549, -0.482, -0.392 and -0.343 respectively within 24 hours after entering the NICU; the r values of the left index finger, the right index finger, the left toe and the right toe were -0.331, -0.292, -0.402 and -0.442 respectively after entering the NICU 24-48 hours, all P < 0.05). Taking lactic acid ≥ 2 mmol/L as the diagnostic standard for metabolic disorder of microcirculation perfusion (total 27 times, accounting for 30.7%). The efficacy of four limbs PI in predicting microcirculation perfusion metabolic disorder were compared. ROC curve analysis showed that the area under the curve (AUC) and 95% confidence interval (95%CI) of left index finger, right index finger, left toe and right toe predicting microcirculation perfusion metabolic disorder were 0.729 (0.609-0.850), 0.767 (0.662-0.871), 0.722 (0.609-0.835), 0.718 (0.593-0.842), respectively. There was no significant difference in AUC compare with each other (all P > 0.05). The cut-off value of PI of right index finger for predicting microcirculation perfusion metabolic disorder was 2.46, the sensitivity was 70.4%, the specificity was 75.4%, the positive likelihood ratio was 2.86, and the negative likelihood ratio was 0.30. CONCLUSIONS: There are no significant differences in PI of bilateral index fingers, bilateral toes in patients with neurosis. However, unilateral upper and lower limbs showed lower PI in the toe than in the index finger. There is a significantly negatively correlation between PI and arterial blood lactic acid in all four limbs. PI can predict the metabolic disorder of microcirculation perfusion, and its cut-off value is 2.46.

Ecological risk assessment and source identification of heavy metal pollution in vegetable bases of Urumqi, China, using the positive matrix factorization (PMF) method.

Heavy metal pollution is a widespread problem and strongly affects human health through the food chain. In this study, the overall pollution situation and source apportionment of heavy metals in soil (Hg, Cd, As, Pb, Ni, Zn, Cu and Cr) were evaluated using various methods including geo-accumulation index (Igeo), potential ecological risk index (RI) and positive matrix factorization combined with Geographical Information System (GIS) to quantify and identify the possible sources to these heavy metals in soils. The results of Igeo showed that this farmland top soil moderate contaminated by Hg, other selected elements with noncontamination level. And the average RI in the top soil was 259.89, indicating a moderate ecological risk, of which Hg and Cd attributed 88.87% of the RI. The results of the PMF model showed that the relative contributions of heavy metals due to atmospheric depositions (18.70%), sewage irrigations (21.17%), soil parent materials (19.11%), industrial and residential coal combustions (17.43%) and agricultural and lithogenic sources (23.59%), respectively. Of these elements, Pb and Cd were came from atmospheric deposition. Cr was attributed to sewage irrigations. As was mainly derived from the soil parent materials. Hg originated from industrial and residential coal combustions, and most of the Cu, Zn and Ni, except for Pb, were predominantly derived from agricultural and lithogenic sources. These results are important in considering management plans to control the aggravation of heavy metal pollution and ultimately to protect soil resources in this region. In addition, this study enhances the understanding of heavy metal contamination occurrence in agroecosystem that helps predicting and limiting the potential of heavy metal exposure to people and ecosystem.

The effect of vanadium on essential element uptake of Setaria viridis' seedlings.

High concentrations of vanadium, a ubiquitous element in the environment, in growing media leads to deformation of root structure and leaf chlorosis and necrosis, consequently affecting the translocations of nutrients and essential elements. However, the effects of vanadium on essential element uptake, and the interactions of essential elements in the presence of vanadium, remain incompletely understood. To elucidate the effects of different concentrations of vanadium on major and trace essential elements and plant growth, a native plant species growing in a vanadium mining area, Setaria viridis (dog tail's grass), was incubated in solutions containing 0-55.8 mg/L vanadium. The shoot accumulation of four major essential elements and five trace essential elements was detected, and the root length and stem height were measured. The results showed that vanadium in soil solution enhanced the accumulation of all major essential elements in shoot. Vanadium concentrations lower than 47.4 mg/L showed an obvious positive (p < 0.05) effect on P accumulation and translocation. In the case of trace essential elements, there were threshold values for solution vanadium stimulation of element uptake. The threshold values for Cu and Zn, Fe, and Mo uptake were 4.3, 16.3, and 40.6 mg/L, respectively. When vanadium levels surpassed these values, accumulation was suppressed and the solution vanadium concentrations attenuated the solution-to-shoot translocation of most of the essential elements. Among the trace essential elements, translocation of Fe was obviously enhanced (p < 0.05) by vanadium. Solution vanadium also enhanced plant growth at lower concentrations and inhibited it at higher levels. The threshold values for stem height and root length were 36.8 and 16.3 mg/L, respectively. Concentrations of 40 and 55.8 mg/L vanadium in soil solution caused a 50% decrease in root length and stem height, respectively, showing that root length of Setaria viridis is more susceptible to vanadium toxicity than stem growth.