The present work covers the preparation of carbon-based nanosorbents by ethylene decomposition on stainless steel mesh without the use of external catalyst for the treatment of water containing nickel ions (Ni2+). The reaction temperature was varied from 650 to 850 degrees C, while reaction time and ethylene to nitrogen flow ratio were maintained at 30 min and 1:1 cm3/min, respectively. Results show that nanosorbents synthesised at a reaction temperature of 650 degrees C had the smallest average diameter (75 nm), largest BET surface area (68.95 m2/g) and least amount of impurity (0.98 wt.% Fe). A series of batch-sorption tests were performed to evaluate the effects of initial pH, initial metal concentration and contact time on Ni2+ removal by the nanosorbents. The equilibrium data fitted well to Freundlich isotherm. The kinetic data were best correlated to a pseudo second-order model indicating that the process was of chemisorption type. Further analysis by the Boyd kinetic model revealed that boundary layer diffusion was the controlling step. This primary study suggests that the prepared material with Freundlich constants compared well with those in the literature, is a promising sorbent for the sequestration of Ni2+ in aqueous solutions.
The environmental contamination by extremophile Aspergillus species, i.e., Aflatoxin B1, is hardly controllable in Southeast Asia and Sub-Saharan Africa, which lack handling resources and controlled storage facilities. Acute aflatoxicosis poisoning from aflatoxin-prone dietary staples could cause acute hepatic necrosis, acute liver failure, and death. Here, as the cheaper, more straightforward, and facile on-site diagnostic kit is needed, we report an ultraviolet-excitable optical aptasensor based on a fluorinated ethylene propylene film strip. Molecular dynamics on the aptamer.AFB1 complex revealed that the AFB1 to the aptamer increases the overall structural stability, suggesting that the aptamer design is suitable for the intended application. Under various influencing factors, the proposed label-free strategy offers a fast 20-min on-site fabrication simplicity and 19-day shelf-life. The one-pot incubation provides an alternative to catalytic detection and exhibited 4 times reusability. The recovery of crude brown sugar, processed peanuts, and long-grain rice were 102.74 ± 0.41 (n = 3), 86.90 ± 3.38 (n = 3), and 98.50 ± 0.42 (n = 3), comparable to High-Performance Liquid Chromatography-Photodiode Array Detector results. This study is novel owing to the peculiar UV-active spectrum fingerprint and the convenient use of hydrophobic film strips that could promote breakthrough innovations and new frontiers for on-site/forensic detection of environmental pollutants.
Design of neutral receptor molecules (ionophores) for beryllium(II) using unsaturated carbonitrile models has been carried out via density functional theory, G3, and G4 calculations. The first part of this work focuses on gas phase binding energies between beryllium(II) and 2-cyano butadiene (2-CN BD), 3-cyano propene (3-CN P), and simpler models with two separate fragments; acrylonitrile and ethylene. Interactions between beryllium(II) and cyano nitrogen and terminal olefin in the models have been examined in terms of geometrical changes, distribution of charge over the entire π-system, and rehybridization of vinyl carbon orbitals. NMR shieldings and vibrational frequencies probed charge centers and strength of interactions. The six-membered cyclic complexes have planar structures with the rehybridized carbon slightly out of plane (16° in 2-CN BD). G3 results show that in 2-CN BD complex participation of vinyl carbon further stabilizes the cyclic adduct by 16.3 kcal mol(-1), whereas, in simpler models, interaction between beryllium(II) and acetonitrile is favorable by 46.4 kcal mol(-1) compared with that of ethylene. The terminal vinyl carbon in 2-CN BD rehybridizes to sp (3) with an increase of 7 % of s character to allow interaction with beryllium(II). G4 calculations show that the Be(II) and 2-CN BD complex is more strongly bound than those with Mg(II) and Ca(II) by 98.5 and 139.2 kcal mol(-1) (-1), respectively. QST2 method shows that the cyclic and acyclic forms of Be(II)-2-CN BD complexes are separated by 12.3 kcal mol(-1) barrier height. Overlap population analysis reveals that Ca(II) can be discriminated based on its tendency to form ionic interaction with the receptor models.
Atmospheric pollution and global warming issues are increasingly becoming major environmental concerns. Fire is one of the significant sources of pollutant gases released into the atmosphere; and tropical biomass fires, which are of particular interest in this study, contribute greatly to the global budget of CO and CO2. This pioneer research simulates the natural biomass burning strategy in Malaysia using an experimental burning facility. The investigation was conducted on the emissions (CO2, CO, and Benzene, Toluene, Ethylbenzene, Xylenes (BTEX)) from ten tropical biomass species. The selected species represent the major tropical forests that are frequently subjected to dry forest fire incidents. An experimental burning facility equipped with an on-line gas analyzer was employed to determine the burning emissions. The major emission factors were found to vary among the species, and the specific results were as follows. The moisture content of a particular biomass greatly influenced its emission pattern. The smoke analysis results revealed the existence of BTEX, which were sampled from a combustion chamber by enrichment traps aided with a universal gas sampler. The BTEX were determined by organic solvent extraction followed by GC/MS quantification, the results of which suggested that the biomass burning emission factor contributed significant amounts of benzene, toluene, and m,p-xylene. The modified combustion efficiency (MCE) changed in response to changes in the sample moisture content. Therefore, this study concluded that the emission of some pollutants mainly depends on the burning phase and sample moisture content of the biomass.
The effect of electron beam radiation on ethylene-propylene diene terpolymer/polypropylene blends is studied as an attempt to develop radiation sterilizable polypropylene/ethylene-propylene diene terpolymer blends suitable for medical devices. The polypropylene/ethylene-propylene diene terpolymer blends with mixing ratios of 80/20, 50/50, 20/80 were prepared in an internal mixer at 165°C and a rotor speed of 50 rpm/min followed by compression molding. The blends and the individual components were radiated using 3.0 MeV electron beam accelerator at doses ranging from 0 to 100 kGy in air and room temperature. All the samples were tested for tensile strength, elongation at break, hardness, impact strength, and morphological properties. After exposing to 25 and 100 kGy radiation doses, 50% PP blend was selected for in vivo studies. Results revealed that radiation-induced crosslinking is dominating in EPDM dominant blends, while radiation-induced degradation is prevailing in PP dominant blends. The 20% PP blend was found to be most compatible for 20-60 kGy radiation sterilization. The retention in impact strength with enhanced tensile strength of 20% PP blend at 20-60 kGy believed to be associated with increased compatibility between PP and EPDM along with the radiation-induced crosslinking. The scanning electron micrographs of the fracture surfaces of the PP/EPDM blends showed evidences consistent with the above contentation. The in vivo studies provide an instinct that the radiated blends are safe to be used for healthcare devices.