Enhanced catalytic complete oxidation of 1,2-dichloroethane over mesoporous transition metal-doped γ-Al_2O_3

High-surface-area mesoprous powders of γ-Al2O3 doped with Cu2+, Cr3+, and V3+ions were prepared via a modified sol–gel method and were investigated as catalysts for the oxidation of chlorinated organic compounds. The composites retained high surface areas and pore volumes comparable with those of undoped γ-Al2O3 and the presence of the transition metal ions enhanced their surface acidic properties. The catalytic activity of the prepared catalysts in the oxidation of 1,2-dichloroethane(DCE) was studied in the temperature range of 250–400°C. The catalytic activity and product selectivity were strongly dependent on the presence and the type of dopant ion. While Cu2+- and Cr3+-containing catalysts showed100% conversion at 300°C and 350°C, V3+-containing catalyst showed considerably lower conversion. Furthermore, while the major products of the reactions over γ-alumina were vinyl chloride(C2H3Cl) and hydrogen chloride(HCl) at all temperatures, Cu- and Cr-doped catalysts showed significantly stronger capability for deep oxidation to CO2.     

Life-cycle assessment of municipal solid waste management alternatives with consideration of uncertainty: SIWMS development and application

This paper describes the development and application of the Stochastic Integrated Waste Management Simulator (SIWMS) model. SIWMS provides a detailed view of the environmental impacts and associated costs of municipal solid waste (MSW) management alternatives under conditions of uncertainty. The model follows a life-cycle inventory approach extended with compensatory systems to provide more equitable bases for comparing different alternatives. Economic performance is measured by the net present value. The model is verified against four publicly available models under deterministic conditions and then used to study the impact of uncertainty on Sydney’s MSW management ‘best practices’. Uncertainty has a significant effect on all impact categories. The greatest effect is observed in the global warming category where a reversal of impact direction is predicted. The reliability of the system is most sensitive to uncertainties in the waste processing and disposal. The results highlight the importance of incorporating uncertainty at all stages to better understand the behaviour of the MSW system.     

Sample Preparation Followed by High Performance Liquid Chromatographic (HPLC) Analysis for Monitoring Muconic Acid as a Biomarker of Occupational Exposure to Benzene

Factors affecting solid phase extraction (SPE) of trans,trans-muconic acid (ttMA), as a benzene biomarker, including sample pH, sample concentration, sample volume, sample flow rate, washing solvent, elution solvent, and type of sorbent were evaluated. Extracted samples were determined by HPLC-UV(highperformance liquid chromatography-ultraviolet). The analytical column was C18, UV wave length was 259 nm, and the mobile phase was H2O/methanol/acetic acid run at flow rate of 1 ml/min. A strong anion exchange silica cartridge was found successful in simplifying SPE. There was a significant difference between recoveries of ttMA when different factors were used (p < .001). An optimum recovery was obtained when sample pH was adjusted at 7. There was no significant difference when different sample concentrations were used (p > .05). The optimized method was then validated with 3 different pools of samples showing good reproducibility over 6 consecutive days and 6 within-day experiments.     

Residues of endosulfan in cotton growing area of Vehari,Pakistan: an assessment of knowledge and awareness of pesticide use and health risks

This study is based on self-reported information collected from selected farmers of Vehari District, Punjab, Pakistan, to determine their technical knowledge and awareness about pesticide use and associated environmental and health risks. Moreover, soil contamination by routinely used persistent organochlorine pesticide, endosulfan, was also evaluated. Survey data revealed very low literacy rate (on an average 9th grade education) and technical knowledge (almost missing) of the farmers in Vehari District. The farmers are unable to fully read and understand the instructions about the use of pesticide marked on the containers. They are not fully aware of pesticide persistence and toxicity (73%), unable to identify cotton pests and diseases (86%), and do not know which crop to grow in cotton adjacent fields (100%). Data also revealed that the farmers (100%) do not follow safety measure during pesticide application and are unaware of pesticide toxicity symptoms in human as well as the basic first-aid practices (89%).

Poor literacy rate and lack of technical knowledge of farmers in Vehari regarding pesticide use and handling are posing serious environmental and health risks among the local inhabitants, particularly among farmers. Soil analysis results showed that concentration of α- and β-endosulfan ranged from 0–14 to 0–14.64 μg/mg, respectively. Principal component analysis showed that soil organic matter is the key soil parameter controlling the occurrence and fate of endosulfan under sandy loam soil conditions of Vehari District. There is a serious need of improving technical and environmental knowledge of farmer about pesticide risks on human health in the studied area, in particular, and the entire country in general. Findings are of great use for policymaking in Pakistan to minimize pesticide risks in Pakistan.

     

Competitive biosorption of lead, cadmium, copper, and arsenic ions using algae

The present study aims to evaluate the competitive biosorption of lead, cadmium, copper, and arsenic ions by using native algae. A series of experiments were carried out in a batch reactor to obtain equilibrium data for adsorption of single, binary, ternary, and quaternary metal solutions. The biosorption of these metals is based on ion exchange mechanism accompanied by the release of light metals such as calcium, magnesium, and sodium. Experimental parameters such as pH, initial metal concentrations, and temperature were studied. The optimum pH found for removal were 5 for Cd²⁺ and As³⁺ and 3 and 4 for Pb²⁺ and Cu²⁺, respectively. Fourier transformation infrared spectroscopy analysis was used to find the effects of functional groups of algae in biosorption process. The results showed that Pb²⁺ made a greater change in the functional groups of algal biomass due to high affinity to this metal. An ion exchange model was found suitable for describing the biosorption process. The affinity constants sequence calculated for single system was K _Pb > K _Cu > K _Cd > K _As; these values reduced in binary, ternary, and quaternary systems. In addition, the experimental data showed that the biosorption of the four metals fitted well the pseudo-second-order kinetics model.     

Dissolution of beryllium in artificial lung alveolar macrophage phagolysosomal fluid

Dissolution of a lung burden of poorly soluble beryllium particles is hypothesized to be necessary for development of chronic beryllium lung disease (CBD) in humans. As such, particle dissolution rate must be sufficient to activate the lung immune response and dissolution lifetime sufficient to maintain chronic inflammation for months to years to support development of disease. The purpose of this research was to investigate the hypothesis that poorly soluble beryllium compounds release ions via dissolution in lung fluid. Dissolution kinetics of 17 poorly soluble particulate beryllium materials that span extraction through ceramics machining (ores, hydroxide, metal, copper-beryllium [CuBe] fume, oxides) and three CuBe alloy reference materials (chips, solid block) were measured over 31 d using artificial lung alveolar macrophage phagolysosomal fluid (pH 4.5). Differences in beryllium-containing particle physicochemical properties translated into differences in dissolution rates and lifetimes in artificial phagolysosomal fluid. Among all materials, dissolution rate constant values ranged from 10⁻⁵ to 10⁻¹⁰ g cm⁻² d⁻¹ and half-times ranged from tens to thousands of days. The presence of magnesium trisilicate in some beryllium oxide materials may have slowed dissolution rates. Materials associated with elevated prevalence of CBD had faster beryllium dissolution rates [10⁻⁷-10⁻⁸ g cm⁻² d⁻¹] than materials not associated with elevated prevalence (p < 0.05).     

Geostatistical Analysis of Spatial and Temporal Variations of Groundwater Level

Groundwater and water resources management plays a key role in conserving the sustainable conditions in arid and semi-arid regions. Applying management tools which can reveal the critical and hot conditions seems necessary due to some limitations such as labor and funding. In this study, spatial and temporal analysis of monthly groundwater level fluctuations of 39 piezometric wells monitored during 12 years was carried out. Geostatistics which has been introduced as a management and decision tool by many researchers has been applied to reveal the spatial and temporal structure of groundwater level fluctuation. Results showed that a strong spatial and temporal structure existed for groundwater level fluctuations due to very low nugget effects. Spatial analysis showed a strong structure of groundwater level drop across the study area and temporal analysis showed that groundwater level fluctuations have temporal structure. On average, the range of variograms for spatial and temporal analysis was about 9.7 km and 7.2 months, respectively. Ordinary and universal kriging methods with cross-validation were applied to assess the accuracy of the chosen variograms in estimation of the groundwater level drop and groundwater level fluctuations for spatial and temporal scales, respectively. Results of ordinary and universal krigings revealed that groundwater level drop and groundwater level fluctuations were underestimated by 3% and 6% for spatial and temporal analysis, respectively, which are very low and acceptable errors and support the unbiasedness hypothesis of kriging. Although, our results demonstrated that spatial structure was a little bit stronger than temporal structure, however, estimation of groundwater level drop and groundwater level fluctuations could be performed with low uncertainty in both space and time scales. Moreover, the results showed that kriging is a beneficial and capable tool for detecting those critical regions where need more attentions for sustainable use of groundwater. Regions in which were detected as critical areas need to be much more managed for using the current water resources efficiently. Conducting water harvesting systems especially in critical and hot areas in order to recharge the groundwater, and altering the current cropping pattern to another one that need less water requirement and applying modern irrigation techniques are highly recommended; otherwise, it is most likely that in a few years no more crop would be cultivated.     

Risk factors and the psychological impacts of the COVID-19 outbreak: perspectives and experiences of Iranian healthcare workers on the frontline

Frontline healthcare workers (HCWs) looking after COVID-19 patients are at high risk of developing mental health problems. Both preventive and interventional initiatives are essential, therefore, to maintain and improve the mental health of HCWs and ultimately to enhance the quality of care that they provide. This qualitative content analysis study, conducted in Iran between September 2020 and February 2021, involved the gathering of data on the issue through face-to-face interviews with 22 HCWs working directly with COVID-19 patients. Data analysis led to the generation of 163 codes, 45 categories (16 risk factors and 29 consequences), and 9 themes. Overall, the results suggest that caring for a patient with COVID-19 is associated with positive and negative psychological impacts. Measures such as increasing sensitivity to crisis situations, self-adjustment skills training, and identifying signs of job burnout owing to moral conflicts can reduce or eliminate the risk of negative psychological consequences among HCWs.     

Vitamin B1 as a metal-free organocatalyst for greener Paal–Knorr pyrrole synthesis

This investigation discloses a greener reaction to prepare pyrrole derivatives. Metal-free catalysts are greener alternatives to existing metal catalysts in synthetic organic chemistry. Indeed, transition metals are often costly and toxic. They may be found as traces in health reaction products such as pharmaceuticals. Alternatively small organic molecules termed “organocatalysts” allow the synthesis of valuable products without traces of toxic metals. Here, we show for the first time the use of vitamin B₁ as new organocatalyst for the Paal–Knorr pyrrole synthesis under ambient conditions. Reaction conditions were optimized for the reaction of hexane-2,5-dione with 4-methoxyaniline. Ethanol was the most effective solvent. The conversion was quantitative using vitamin B₁, by comparison with a low yield of 30?% without catalysis. The best conditions were performed in ethanol with 5?mol % of vitamin B₁ during 1?h. This reaction was tested using various aromatic amines. To conclude the use of vitamin B₁ for the Paal–Knorr pyrrole, cyclocondensation has mild reaction conditions, is simple to perform, and gives moderate to excellent yields. It is therefore a promising reaction for the preparation of various pyrrole derivatives.