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The Impact of Urbanisation on the Water Quality of Lake Chivero, Zimbabwe
Published in Innocent Nhapi, Options for Wastewater Management in Harare, Zimbabwe, 2014
The spatial variation of nitrogen and phosphorus for the period July 2000 to December 2001 is shown in Fig. 3.6a. The lake water is fairly mixed as evidenced by the fact that the sampling points are distributed wide apart (Fig 3.1) and depth samples were collected, but still have almost same levels of both nitrogen and phosphorus. Soluble ortho-phosphates were only analysed for the top water layer at depths of 0.5, 1.0 and 2.0 m (Fig 3.6b). From physical observations, this is where most algae are concentrated. The results gave a mean concentration of 0.4±0.2 mg/l as P (about 70% of the mean lake TP concentration). This means that most of the phosphorus is available as soluble P, which could trigger further water hyacinth and algal growth. Ortho-phosphates are mainly associated with domestic sewage contamination.
Photoelectrochemical Ammonia Production
Published in Anirban Das, Gyandshwar Kumar Rao, Kasinath Ojha, Photoelectrochemical Generation of Fuels, 2023
Arpna Jaryal, Anjali Verma, Kamalakannan Kailasam
This spectrophotometric method of ammonia quantification also suffers from limitations: (i) inaccurate ammonia quantification in an aqueous medium with pH less than 7 due to NaOCl instability, (ii) overestimated NH3 detection in reaction medium with concentrations above 500 µg L−1,60 (iii) ortho-chlorophenol is formed when phenol is used as a reactant, which is poisonous, hazardous, and volatile. Hence it is replaced by salicylic acid, which is a much safer reagent to handle. Citrate buffer is used to prevent the precipitation of ions that might form in the alkaline medium which further stabilizes the pH of the reaction mixture.
Sorption of Selected Organic Pollutants by Fly Ash
Published in John M. Bell, Proceedings of the 43rd Industrial Waste Conference May 10, 11, 12, 1988, 1989
Kashi Banerjee, P. Y. Horng, Paul N. Cheremisinoff, M. S. Sheih, S. L. Cheng
Butanol and ortho-Xylene. Isotherm tests were performed mixing equal amounts of butanol and ortho-Xylene. The adsorption capacity of flyash on butanol and ortho-Xylene during multi component studies are 240 µg/g and 330 μg/g, respectively, whereas the adsorption capacity of the same fly ash on Butanol and ortho-Xylene during single component systems are 253 μg/g and 1090 µg/g, respectively (Table IV).
Use of biogenic NiONPs as nanocatalyst in Kumada-Corriu coupling reaction
Published in Inorganic and Nano-Metal Chemistry, 2022
Zahir Abbas, Meena Nemiwal, Ankita Dhillon, Dinesh Kumar
1H and 13C NMR spectra were recorded on 500 MHz NMR instrument. Protons of phenyl rings were found to be in the range of 6.6–7.9 ppm. As the peaks obtained for 4 ortho protons were split out into a doublet in the range of 7.61–7.59 ppm with J value 7.66 Hz, and the peaks obtained from 4 meta protons were split out into triplet due to ortho and para protons. The peak for two para protons was found to be doublet due to meta protons. The downfield shift of ortho, meta and para protons confirms the phenyl group in place of iodine attached to it. 1H NMR (500 MHz, CDCl3) δ (ppm): 7.61–7.59 (d, J = 7.66 Hz, 4H) for ortho protons, 7.46–7.43 (t, J = 7.26 Hz, 4H) for meta protons, 7.37–7.34 (d, J = 6.20 Hz, 2H) for para protons (Figure 12).
Effect of ortho-para conversion on economics of liquid hydrogen tanker with pressure cargo tanks
Published in Ships and Offshore Structures, 2018
Hwalong You, Junkeon Ahn, Sangkwon Jeong, Daejun Chang
Hydrogen exists as ortho hydrogen or para hydrogen depending on the direction of the spins of its two protons (Buntkowsky et al. 2006). At atmospheric conditions, an equilibrium mixture of hydrogen consists of 25% para hydrogen and 75% ortho hydrogen. The equilibrium concentration is determined as a function of temperature. The content of para hydrogen is almost 99.8% at −253 °C, which is the normal boiling point of LH2 (Peng and Ahluwalia 2013). This means that the ortho hydrogen is converted to para hydrogen naturally. The conversion is an exothermic reaction because the energy state of the para hydrogen is lower than that of the ortho hydrogen. The conversion rate in the absence of a catalyst can be determined by using Equation (1) (Barron 1985). From Equation (1), the ortho (para) concentration can be calculated during conversion process:
Complexes of copper(I) with aromatic compounds facilitate selective electrophilic aromatic substitution
Published in Journal of Coordination Chemistry, 2018
Magal Saphier, Inna Levitsky, Alexandra Masarwa, Oshra Saphier
Quantum mechanical calculations of the structure of the Cu(I)-phenol complex [2] (Figure 1) indicate that copper(I) is bound mainly to one carbon-carbon bond of the ring and that the carbon hydrogen bond ortho to the hydroxyl group is elongated, 1.113 Å, compared to the para bound, 1.090 Å, and native phenol, 1.094 Å. Furthermore, all the carbon-carbon bonds in the complex are elongated by ∼0.04 Å compared to the native phenol. The crystal structure of Cu(I)(C6H6) [3] supports the quantum mechanical calculations. In the crystal structure copper(I) is bound mainly to one carbon-carbon bond, the benzene ring in the complex is distorted and distances between carbons vary from 1.25 Å to 1.41 Å. The calculated structure of the Cu(I)-phenol complex and the crystal structure of Cu(I)(C6H6) can be explained by charge transfer from the low bonding orbital of the aromatic system to the positively charged Cu+, and back donation from the fully occupied d orbitals of the monovalent copper to the π* anti-bonding orbital of the aromatic system (Figure 2). The localization of the charge on the π* anti-bonding orbital resembles an excited state of the aromatic system (Negative charge located on the anti-bounding orbital) and may cause distortion of the ring structure and facilitate selective substitutions. That finding supports the reported role of copper(I) in the Ullmann reaction mechanism [4] which involves two copper(I) ions, one interacts and activates the aromatic system and the second substitutes the "ortho" atom (bromine in the article) to form a copper-carbon intermediate. This intermediate reacts very rapidly with the substituent (OH- in the article) to form the ortho isomer exclusively.