Synthesis of bifunctional nanostructured adsorbents based on anionic/cationic clays: effect of arrangement on simultaneous adsorption of cadmium and arsenate.

The development of bifunctional hybrid materials based on natural clays and layered double hydroxide (LDH) and their application on the simultaneous adsorption of Cd(II) and As(V) was investigated in this work. Two different synthesis routes, in situ and assembly, were employed to obtain the hybrid materials. Three types of natural clays, namely bentonite (B), halloysite (H), and sepiolite (S), were used in the study. These clays are characterized by a laminar, tubular, and fibrous structural arrangement, respectively. The physicochemical characterization results indicate that the hybrid materials were formed through interactions between the Al-OH and Si-OH groups present in the natural clays, and the Mg-OH and Al-OH groups present in the LDH for both synthesis routes. However, the "in situ" route yields a more homogenous material because the LDH formation is performed on the natural clay surface. The hybrid materials showed an anion and cation exchange capacity up to 200.7 meq/100 g and an isoelectric point near 7. The arrangement of natural clay has no impact on the properties of hybrid material but influences the adsorption capacity. The adsorption of Cd(II) onto hybrid materials was enhanced in comparison with natural clays, obtaining adsorption capacities of 80, 74, 65, and 30 mg/g for 15:1 (LDH:H)INSITU, 1:1 (LDH:S)INSITU, 1:1 (LDH:B)INSITU, and 1:1 (LDH:H)INSITU, respectively. The adsorption capacities of hybrid materials to adsorb As(V) were between 20 and 60 µg/g. The 15:1 (LDH:H)INSITU sample showed the best adsorption capacity being ten folds greater than halloysite and LDH. In all cases, the hybrid materials showed a synergistic effect for Cd(II) and As(V) adsorption. The adsorption study of Cd(II) onto hybrid materials showed that the primary adsorption mechanism is cation exchange between the interlayer cations in natural clay and Cd(II) in the aqueous solution. The adsorption of As(V) showed that the adsorption mechanism is attributed to anion exchange between CO23- in the interlayer space of LDH and H2ASO4- in the solution. The simultaneous adsorption of As (V) and Cd (II) shows that, during the As(V) adsorption, there is no competition by the adsorption sites. Still, the adsorption capacity towards Cd(II) was enhanced 1.2-folds. This study ultimately revealed that the arrangement of clay has a significant influence on the adsorption capacity of the hybrid material. This can be attributed to the similar morphology between the hybrid material and natural clays, as well as the important diffusion effects observed in the system.

Hypercoagulability status, operative mortality, and long-term survival in patients operated on for mesenteric venous thrombosis.

OBJECTIVE: Mesenteric venous thrombosis (MVT) is a rare cause of acute surgical abdomen, with high mortality. The aim of this study was to analyze long-term outcomes and possible factors influencing its prognosis. METHODS: All patients who underwent urgent surgery for MVT from 1990 to 2020 in our center were reviewed. Epidemiological, clinical, and surgical data; postoperative outcomes; origin of thrombosis; and long-term survival were analyzed. Patients were divided into two groups: primary MVT (hypercoagulability disorders or idiopathic MVT) and secondary MVT (underlying disease). RESULTS: Fifty-five patients, 36 (65.5%) men and 19 (34.5%) women, mean age 66.7 years (standard deviation: ±18.0 years), underwent surgery for MVT. Arterial hypertension (63.6%) was the most prevalent comorbidity. Regarding the possible origin of MVT, 41 (74.5%) patients had primary MVT and 14 (25.5%) patients had secondary MVT. From these, 11 (20%) patients had hypercoagulable states, 7 (12.7%) had neoplasia, 4 (7.3%) had abdominal infection, 3 (5.5%) had liver cirrhosis, 1 (1.8%) patient had recurrent pulmonary thromboembolism, and 1 (1.8%) had deep venous thrombosis. Computed tomography was diagnostic of MVT in 87.9% of the cases. Intestinal resection was performed in 45 patients due to ischemia. Only 6 patients (10.9%) had no complication, 17 patients (30.9%) presented minor complications, and 32 patients (58.2%) presented severe complications according to the Clavien-Dindo classification. Operative mortality was 23.6%. In univariate analysis, comorbidity measured by the Charlson index (P = .019) and massive ischemia (P = .002) were related to operative mortality. The probability of being alive at 1, 3, and 5 years was 66.4%, 57.9%, and 51.0%, respectively. In univariate analysis of survival, age (P < .001), comorbidity (P < .001), and type of MVT (P = .003) were associated with a good prognosis. Age (P = .002; hazard ratio: 1.05, 95% confidence interval: 1.02-1.09) and comorbidity (P = .019; hazard ratio: 1.28, 95% confidence interval: 1.04-1.57) behaved as independent prognostic factors for survival. CONCLUSIONS: Surgical MVT continues to show high lethality. Age and comorbidity according to the Charlson index correlate well with mortality risk. Primary MVT tends to have a better prognosis than secondary MVT.

Study of Molybdenite Floatability: Effect of Clays and Seawater.

Current challenges in froth flotation are the presence of complex gangues and the use of low-quality waters, such as seawater. In this scenario, the recovery of molybdenum minerals is difficult, mainly due to the hydrophobic faces' physicochemical changes. In the present study, the natural floatability of pure molybdenite was analyzed by using microflotation assays, and hydrophobicity was measured by performing contact-angle measurements. The impact of two clays, kaolin (non-swelling) and Na-montmorillonite (swelling), was studied. The behavior in freshwater and seawater at pH 8 was compared, considering the current condition of the Cu/Mo mining industries, which use seawater in their operations. The presence of clays lowered the natural floatability of molybdenite precisely because they adhere to the surface and reduce its contact angle. However, the intensity with which they cause this phenomenon depends on the type of water and clay. Kaolin strongly adheres to the valuable mineral in both freshwater and seawater. For its part, Na-montmorillonite does it with greater intensity in a saline medium, but in freshwater, a high concentration of phyllosilicate is required to reduce the hydrophobicity of molybdenite. The clays' adherence was validated by scanning electron microscopy (SEM) analysis.

A new insight into the restriction of Cr(VI) removal performance of activated carbon under neutral pH condition.

Activated carbon has been widely used to remove hazardous Cr(VI); however, the impact of Cr2O3 precipitate on gradually declining removal ability as pH increases has received little attention. Herein, to investigate the effect of Cr2O3, SEM-EDX (scanning electron microscope-energy dispersive X-ray analysis) coupling elements mapping of chromium-loaded powdered activated carbon (PAC) revealed that a chromium layer was formed on the PAC exterior after being treated with Cr(VI) at pH 7. XPS (X-ray photoelectron spectroscopy) study confirmed that 69.93% and 39.91% Cr2O3 precipitated on the PAC surface at pH 7 and pH 3, respectively, corresponding to 17.77 mg/g and 20 mg/g removal capacity. Exhausted PAC had a removal efficiency of 92.43% after Cr2O3 being washed by H2SO4 solution, which was much higher than the removal efficiency of 51.27 % after NaOH washing. This further verified that the intrinsically developed Cr2O3 precipitate on PAC under neutral conditions limited the durability of PAC as an adsorbent. Consecutive elution assessments confirmed that adsorption and reduction ability both declined as pH increased. Raman spectroscopy and C 1s spectra of materials demonstrated two distinct Cr(VI) removal mechanisms under pH 3 and pH 7. In conclusion, the exhausted AC after Cr(VI) adsorption can be rejuvenated after the surface coated Cr2O3 is washed by the acid solution, which can expand the longevity of AC and recover Cr(III).

Highly surface activated carbon to remove Cr(VI) from aqueous solution with adsorbent recycling.

To enhance the inferior removal capability of aqueous Cr(VI) by commercial activated carbon under neutral conditions. The emerging ball milling technology was employed and the removal efficiency of Cr(VI) by ball-milled highly activated carbon (HAC) increased from 68.3% to 99.0% under pH 6 and from 42.7% to 77.8% under pH 7 compared to pristine activated carbon (AC), respectively. Raman spectra and Boehm's titration results signified that the enhanced Cr(VI) removal performance of HAC under neutral conditions was associated with the enriched surface acid functional groups, in which the content of COOH groups increased from 0.31 mmol/g to 0.97 mmol/g. Two Cr(VI) removal mechanisms were proposed established on the acid and alkalic solution washed chromium-loaded HAC, involving the reduction of Cr(VI) to Cr(III) subsequently accompany with the formation of chromium hydroxides on the surface and inside the pores of HAC, and the bonding of CrO42- on the surface COOH groups, as confirmed by SEM-EDX element mapping and specific surface area and porosity measurements. The Pseudo-second order model and Freundlich model fitted the adsorption kinetic and isotherm of AC and HAC well severally, suggesting that the specific interaction of Cr(VI) with the HAC surface and the Cr(VI) removal was multi-layer adsorption. Thermodynamic study exhibited the spontaneity of Cr(VI) removal on ball-milled HAC was increased. Reusability and regeneration studies of HAC denoted the potential application on Cr(VI) uptake under neutral conditions.

Comparative Analysis of Mass-Spectrometry-Based Proteomic Methods for Protein Target Discovery Using a One-Pot Approach.

Recently, several mass-spectrometry- and protein-denaturation-based proteomic methods have been developed to facilitate protein target discovery efforts in drug mode-of-action studies. These methods, which include the stability of proteins from rates of oxidation (SPROX), pulse proteolysis (PP), chemical denaturation and protein precipitation (CPP), and thermal proteome profiling (TPP) techniques, have been used in an increasing number of applications in recent years. However, while the advantages and disadvantages to using these different techniques have been reviewed, the analytical characteristics of these methods have not been directly compared. Reported here is such a direct comparison using the well-studied immunosuppressive drug, cyclosporine A (CsA), and the proteins in a yeast cell lysate. Also described is a one-pot strategy that can be utilized with each technique to streamline data acquisition and analysis. We find that there are benefits to utilizing all four strategies for protein target discovery including increased proteomic coverage and reduced false positive rates that approach 0%. Moreover, the one-pot strategy described here makes such an experiment feasible, because of the 10-fold reduction in reagent costs and instrument time it affords.