Development of zerovalent iron and titania (Fe0/TiO2) composite for oxidative degradation of dichlorophene in aqueous solution: synergistic role of peroxymonosulfate (HSO5-).

Binary composite of zerovalent iron and titanium dioxide (Fe0/TiO2) was synthesized for the catalytic removal of dichlorophene (DCP) in the presence of peroxymonosulfate (PMS). The as-prepared composite (Fe0/TiO2) exhibits synergistic effect and enhanced properties like improved catalytic activity of catalyst and greater magnetic property for facile recycling of catalyst. The results showed that without addition of PMS at reaction time of 50 min, the percent degradation of DCP by TiO2, Fe0, and Fe0/TiO2 was just 5%, 11%, and 12%, respectively. However, with the addition of 0.8 mM PMS, at 10 min of reaction time, the catalytic degradation performance of Fe0, TiO2, and Fe0/TiO2 was significantly improved to 82%, 18%, and 88%, respectively. The as-prepared catalyst was fully characterized to evaluate its structure, chemical states, and morphology. Scanning electron microscopy results showed that in composite TiO2 causes dispersion of agglomerated iron particles which enhances porosity and surface area of the composites and X-ray diffraction (XRD), energy dispersive X-ray (EDX), and Fourier-transform infrared (FTIR) results revealed successful incorporation of Fe0, and oxides of Fe and TiO2 in the composite. The adsorption-desorption analysis verifies that the surface area of Fe0/TiO2 is significantly larger than bare Fe0 and TiO2. Moreover, the surface area, particle size, and crystal size of Fe0/TiO2 was surface area = 85 m2 g-1, particle size = 0.35 µm, and crystal size = 0.16 nm as compared to TiO2 alone (surface area = 22 m2 g-1, particle size = 4.25 µm, and crystal size = 25.4 nm) and Fe0 alone (surface area = 65 m2 g-1, particle size = 0.9 µm, and crystal size = 7.87 nm). The as-synthesized material showed excellent degradation performance in synthesized wastewater as well. The degradation products and their toxicities were evaluated and the resulted degradation mechanism was proposed accordingly. The toxicity values decreased in order of DP1 > DP5 > DP2 > DP3 > DP4 and the LC50 values toward fish for 96-h duration decreased from 0.531 to 67.2. This suggests that the proposed technology is an excellent option for the treatment of antibiotic containing wastewater.

Bismuth-Doped Nano Zerovalent Iron: A Novel Catalyst for Chloramphenicol Degradation and Hydrogen Production.

In this study, we showed that doping bismuth (Bi) at the surface of Fe0 (Bi/Fe0, bimetallic iron system)-synthesized by a simple borohydride reduction method-can considerably accelerate the reductive degradation of chloramphenicol (CHP). At a reaction time of 12 min, 62, 68, 74, 95, and 82% degradation of CHP was achieved with Fe0, Bi/Fe0-1 [1% (w/w) of Bi], Bi/Fe0-3 [3% (w/w) of Bi], Bi/Fe0-5 [5% (w/w) of Bi], and Bi/Fe0-8 [8% (w/w) of Bi], respectively. Further improvements in the degradation efficiency of CHP were observed by combining the peroxymonosulfate (HSO5 -) with Bi/Fe0-5 (i.e., 81% by Bi/Fe0-5 and 98% by the Bi/Fe0-5/HSO5 - system at 8 min of treatment). Interestingly, both Fe0 and Bi/Fe0-5 showed effective H2 production under dark conditions that reached 544 and 712 µM by Fe0 and Bi/Fe0-5, respectively, in 70 mL of aqueous solution containing 0.07 g (i.e., at 1 g L-1 concentration) of the catalyst at ambient temperature.

Morbidity and Mortality Associated With Pediatric Critical Mediastinal Mass Syndrome.

Objective The critical mediastinal mass syndrome (CMMS) is a life-threatening condition and is challenging for physicians. We analyse the clinicopathological profile and outcome of CMMS from a large tertiary-care pediatric oncology center in Pakistan. Methods We retrospectively reviewed the medical record of a tertiary-care hospital in Pakistan from April 2017 to September 2019 for all children (1 month-16 years) who presented with an anterior mediastinal mass (AMM). A CMMS case is defined as a child with an AMM presenting with cardiorespiratory compromise and needing intensive care support. Demographic data, clinical profile, pathological diagnosis, and outcome of all such children were recorded. Descriptive statistics were applied using the Statistical Package for the Social Sciences (SPSS), version 22 (IBM Corp., Armonk, NY). Results Of the total 221 mediastinal masses, 61 children were diagnosed as CMMS and enrolled in the study. The mean age was 9 ± 3.3 years, and 68.9%% were male; 65.6% of patients had a weight for age less than the fifth percentile. A total of 49.2% of patients had a duration of illness of more than one month before diagnosis. Fever (97.6%) and lymphadenopathy (82%) were the most common findings, along with respiratory and cardiovascular signs and symptoms; 9.8% had superior vena cava syndrome. The pericardial effusion was present in 54.6% and 27.9% had pleural effusion. Peripheral blood flow cytometry made the diagnosis in 59%, peripheral lymph node biopsy in 13%, mediastinal core biopsy in 5%, and pleural fluid flow cytometry in one case; 62.3% had a white blood cell count of >100,000/mm3. A total of 72.1% (n=44) cases were diagnosed as T-cell acute lymphoblastic leukemia in our cohort. Clinical and laboratory tumor lysis syndrome developed in 10% and 73% of cases, respectively. Mechanical ventilation was required in 9.8% of the cohort. Mortality was reported in 10 (16.4%) patients. Conclusion We found that the 100% fatality rate with controlled positive pressure ventilation and spontaneous breathing is ideal. Tumour lysis syndrome was the most common morbidity in our cohort.