The Experts below are selected from a list of 105 Experts worldwide ranked by ideXlab platform
Frédéric J. Doucet - One of the best experts on this subject based on the ideXlab platform.
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Thermochemical treatment of platinum group metal tailings with Ammonium salts for major element recovery
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Sameera Mohamed, Keabetswe Lehong, Wladyslaw Altermann, Elizabet M. Van Der Merwe, Frédéric J. DoucetAbstract:It was recently demonstrated that the extraction of major elements from South African Platinum Group Metals (PGM) tailings can be achieved via thermochemical treatment with Ammonium sulphate followed by aqueous dissolution. The current study uses the insight gained from the previous work and investigates and compares major element extraction efficiencies obtained using Ammonium sulphate and three other Ammonium salts (Ammonium Bisulphate vs Ammonium chloride vs Ammonium nitrate) as extracting agents at five different temperatures (350–550 °C). Overall, Ammonium sulphate was the most promising reagent for the co-extraction of major elements, with the best extraction efficiencies achieved for aluminium (ca. 60%) and calcium (ca. 80%), alongside chromium (ca. 29%), iron (ca. 35%), magnesium (ca. 25%) and silicon (ca. 32%). In contrast, Ammonium chloride and Ammonium nitrate extracted smaller quantities of these elements, in particular chromium which was hardly extracted (≤ 1.2%), whereas calcium was nearly equally extracted for all salts (70–80%). It could not be ascertained whether the plagioclase phase, as anorthite, reacted with Ammonium salts during the thermochemical step, but it was found to dissolve nearly completely during the acid leaching step in the absence of thermochemical processing. This phase was the main contributor to calcium and aluminium in solution. The greatest effect of temperature was on the flowability characteristic of the reaction product after treatment rather than on elemental extraction efficiencies. Thermochemical treatment using Ammonium sulphate represents the most promising route for extracting valuable elements from PGM tailings, which could be subsequently converted into value-added products.
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Ammonium sulphate and or Ammonium Bisulphate as extracting agents for the recovery of aluminium from ultrafine coal fly ash
Hydrometallurgy, 2017Co-Authors: Elizabet M. Van Der Merwe, Sameera Mohamed, Clarissa L. Gray, Barbara A. Castleman, Richard A. Kruger, Frédéric J. DoucetAbstract:The Council for Geoscience, the University of Pretoria and the National Research Foundation of South Africa (NRF; Grant No. 93641).
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Ammonium sulphate and/or Ammonium Bisulphate as extracting agents for the recovery of aluminium from ultrafine coal fly ash
Hydrometallurgy, 2017Co-Authors: Elizabet M. Van Der Merwe, Sameera Mohamed, Clarissa L. Gray, Barbara A. Castleman, Richard A. Kruger, Frédéric J. DoucetAbstract:The Council for Geoscience, the University of Pretoria and the National Research Foundation of South Africa (NRF; Grant No. 93641).
Roy M. Harrison - One of the best experts on this subject based on the ideXlab platform.
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The effect of sulphurous air pollutant exposures on symptoms, lung function, exhaled nitric oxide, and nasal epithelial lining fluid antioxidant concentrations in normal and asthmatic adults
Occupational and environmental medicine, 2003Co-Authors: W.s. Tunnicliffe, Roy M. Harrison, Frank J. Kelly, Chrissi Dunster, J G AyresAbstract:Aims: To explore the effects in normal and asthmatic adults of exposure to 200 ppb sulphur dioxide (SO2) and 200 mg/m 3 and 2000 mg/m 3 aerosols of Ammonium Bisulphate (AB) and sulphuric acid (SA) (MMD 0.3 mm). Methods: Exposures were placebo controlled, for one hour at rest, double blind in random order. DFEV1 was the primary outcome; secondary outcomes included symptoms, ventilation, exhaled nitric oxide (NO) concentrations, and nasal lavage fluid ascorbic (AA) and uric acid (UA) concentrations. Results: There were no significant changes in spirometry or symptoms with any exposure in either group. SO2 exposure was associated with an increased respiratory rate relative to air exposure in the asthmatic group (SO2: 958.9 breaths/hour; air: 906.8 breaths/hour) but the mean volume breathed did not differ significantly (SO2: 318.8 litres; air: 311.4 litres). AB exposures were associated with a significant rise in (NO) in the asthmatic (+1.51 ppb, and +1.39 ppb), but not in the normal group. Mean pre- and post- exposure (AA) tended to be higher in the normal than in the asthmatic group. Within each group, (AA) did not change significantly with any exposure. Post-exposure (UA) were greater than pre-exposure concentrations for all exposures, significantly so in the normal group for all exposures except SO2. There were no significant differences in the mean change in (UA) for any exposure relative to air. Conclusions: The pollutant exposure concentrations employed in this study were generally much greater than ambient. It is unlikely that short lived exposures at lower concentrations would show significant effects, but effects of longer term lower concentration exposures cannot be ruled out.
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Biogenic sulphur emissions and inferred non‐sea‐salt‐sulphate cloud condensation nuclei in and around Antarctica
Journal of Geophysical Research: Atmospheres, 1997Co-Authors: Colin D. O'dowd, Jason Lowe, Michael H. Smith, Brian Davison, C. Nicholas Hewitt, Roy M. HarrisonAbstract:Accumulation mode aerosol properties and biogenic sulphur emissions over the South Atlantic and Antarctic Oceans are examined. Two contrasting air masses, polar and maritime, each possessing distinct aerosol properties, were encountered during the summer months. By examining aerosol volatile properties, polar air masses arriving from the Antarctic continent were shown to consist primarily Of H2SO4 in the accumulation mode size range, with inferred NH+4 to SO=4 molar ratios close to zero. By comparison, air masses of temperate maritime origin were significantly neutralized with molar ratios of ≈1. These results suggest a deficit of ammonia in polar air masses compared with that in maritime air masses. Dimethyl sulphide (DMS) exhibited no correlation with its putative aerosol oxidation products, although spatial coherence in atmospheric concentrations of DMS, methane sulphonic acid (MSA), and non-sea-salt (nss)-sulphate mass was observed. Volatility analysis, used to infer nss-sulphate cloud condensation nuclei (nss-sCCN) active at a supersaturation of ≈0.2%, indicates that nss-sCCN mass and number concentration were best correlated with MSA mass (r≈0.63). Aerosol volatility identified the presence of MSA in submicron non-sea-salt aerosol; however, its contribution to the aerosol mass was small relative to the contribution of sulphuric acid and Ammonium Bisulphate/sulphate aerosol. The marine sulphur cycle appears strongly coupled to the sea-salt cycle with, typically, 80–90% of nss-sulphate thought to be internally mixed with sea-salt aerosol. During the austral Summer of 1992/1993, a period of strong biological productivity in the Weddell Sea and sub-Antarctic Ocean, particularly during ice-melt, the cruise-average DMS flux of 61 μg m−2 d−1 corresponded to a very modest average nss-sCCN concentration of 21 cm−3. Observed peak values of DMS flux and inferred nss-CCN concentrations during the cruise were 477 μg m−2 d−1 and 64 cm−3, respectively. Events of new particle formation were identified in the Weddell Sea and occurred under conditions of high DMS flux and low aerosol surface area.
Akhtar Rasool - One of the best experts on this subject based on the ideXlab platform.
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Significantly enhanced biomass production of a novel bio-therapeutic strain Lactobacillus plantarum (AS-14) by developing low cost media cultivation strategy
Journal of Biological Engineering, 2017Co-Authors: Asma Manzoor, Javed Iqbal Qazi, Ikram Ul Haq, Hamid Mukhtar, Akhtar RasoolAbstract:Background Probiotic bacteria are becoming an important tool for improving human health, controlling diseases and enhancing immune responses. The availability of a cost effective cultivation conditions has profound effect on the efficiency and role of probiotic bacteria. Therefore the current study was conducted with an objective to develop a low cost growth medium for enhancing the biomass production of a bio-therapeutic bacterial strain Lactobacillus plantarum AS-14. In this work the isolation of Lactobacillus plantarum AS-14 bacterial strain was carried out from brinjal using cheese whey as a main carbon source. Moreover, the effect of four other nutritional factors besides cheese whey was investigated on the enhanced cell mass production by using response surface methodology (RSM). Results The best culture medium contained 60 g/l cheese whey, 15 g/l glucose and 15 g/l corn steep liquor in addition to other minor ingredients and it resulted in maximum dry cell mass (15.41 g/l). The second-order polynomial regression model determined that the maximum cell mass production (16.02 g/l) would be obtained at temperature 40°C and pH 6.2. Comparative studies showed that cultivation using cheese whey and corn steep liquor with other components of the selected medium generated higher biomass with lower cost than that of De Man, Rogosa and Sharpe (MRS) medium under similar cultivation conditions (pH 6.2 and temperature 40°C). Conclusion It is evident that the cell biomass of L. Plantarum AS-14 was enhanced by low cost cultivation conditions. Moreover, corn steep liquor and Ammonium Bisulphate were perceived as low-cost nitrogen sources in combination with other components to substitute yeast extract. Of all these factors, cheese whey, corn steep liquor, yeast extract and two operating conditions (temperature and pH) were found to be the most significant parameters. Thus the cost effective medium developed in this research might be used for large-scale commercial application where economics is quite likely important.
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Significantly enhanced biomass production of a novel bio-therapeutic strain Lactobacillus plantarum (AS-14) by developing low cost media cultivation strategy
Journal of biological engineering, 2017Co-Authors: Asma Manzoor, Javed Iqbal Qazi, Ikram Ul Haq, Hamid Mukhtar, Akhtar RasoolAbstract:Probiotic bacteria are becoming an important tool for improving human health, controlling diseases and enhancing immune responses. The availability of a cost effective cultivation conditions has profound effect on the efficiency and role of probiotic bacteria. Therefore the current study was conducted with an objective to develop a low cost growth medium for enhancing the biomass production of a bio-therapeutic bacterial strain Lactobacillus plantarum AS-14. In this work the isolation of Lactobacillus plantarum AS-14 bacterial strain was carried out from brinjal using cheese whey as a main carbon source. Moreover, the effect of four other nutritional factors besides cheese whey was investigated on the enhanced cell mass production by using response surface methodology (RSM). The best culture medium contained 60 g/l cheese whey, 15 g/l glucose and 15 g/l corn steep liquor in addition to other minor ingredients and it resulted in maximum dry cell mass (15.41 g/l). The second-order polynomial regression model determined that the maximum cell mass production (16.02 g/l) would be obtained at temperature 40°C and pH 6.2. Comparative studies showed that cultivation using cheese whey and corn steep liquor with other components of the selected medium generated higher biomass with lower cost than that of De Man, Rogosa and Sharpe (MRS) medium under similar cultivation conditions (pH 6.2 and temperature 40°C). It is evident that the cell biomass of L. Plantarum AS-14 was enhanced by low cost cultivation conditions. Moreover, corn steep liquor and Ammonium Bisulphate were perceived as low-cost nitrogen sources in combination with other components to substitute yeast extract. Of all these factors, cheese whey, corn steep liquor, yeast extract and two operating conditions (temperature and pH) were found to be the most significant parameters. Thus the cost effective medium developed in this research might be used for large-scale commercial application where economics is quite likely important.
Ron Zevenhoven - One of the best experts on this subject based on the ideXlab platform.
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Methods for recovery and re-use of additive chemicals during CO2 mineralisation
Journal of Water Process Engineering, 2017Co-Authors: Evelina Koivisto, Ron ZevenhovenAbstract:Abstract This paper presents options for the recovery and recirculation of Ammonium sulphate (AS) and/or Ammonium Bisulphate (ABS) additive in a process for mineral carbonation referred to as the AA route. The process uses magnesium silicate rock (serpentinite) reacting with AS and/or ABS in order to extract magnesium which subsequently will be carbonated. A challenge still is to find ways to recover the chemicals in an efficient way and this paper addresses options for this. The concepts and possible implementation for reverse osmosis separation, precipitation by the addition of alcohol, multiple-step extraction and ion selective membranes/ion exchange resins are presented. It was shown that reverse osmosis membranes will need high pressures in order to achieve sufficient separation. Addition of alcohol (ethanol) will make it possible to precipitate AS, magnesium and iron sulphates. This enables some separation of AS from ABS since ABS remains dissolved in the solution, but subsequent separation and recovery of ethanol from water is in turn required. Multiple-step extraction was tested with a procedure containing both thermal and wet extraction. It was shown, however, that precipitation of some species resulted rather than extraction, which has to be further investigated. The multiple-step extraction procedure included different ratios of rock: AS and/or ABS; it was shown that AS plays an important role in the thermal extraction even if ABS is a more aggressive chemical. The option to apply ion selective membranes for the recovery of ABS is part of ongoing work: first results are promising, as presented here.
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Extraction of magnesium from four Finnish magnesium silicate rocks for CO2 mineralisation—part 2: Aqueous solution extraction
Hydrometallurgy, 2016Co-Authors: Rickard Erlund, Evelina Koivisto, Mats Fagerholm, Ron ZevenhovenAbstract:Abstract Extraction of magnesium from minerals serpentinite, amphibolite and diopside for mineral carbonation in Finland are compared. In part two of this study, extraction in an aqueous solution reactor is the main focus, using solvents such as Ammonium Bisulphate (ABS), Ammonium sulphate (AS) and hydrochloric acid. The advantage of using a mixture of ABS and AS as solvent is analysed. A process suggested containing an aqueous solution extraction reactor is compared to a mineral carbonation process with a thermal solid/solid extraction step. Extracted elements, mainly magnesium, are measured with atomic absorption spectroscopy (AAS). The two serpentines tested in the study showed sufficient reactivities required for an efficient carbonation process, while the two other minerals' reactivities were insufficient. The best extraction results obtained for the two serpentines give a binding capacity of CO2 that is 292 and 260 kg CO2/ton rock. Reactivity with a minimal amount of water, and recirculating and regenerating solvent salts is analysed.
Asma Manzoor - One of the best experts on this subject based on the ideXlab platform.
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Significantly enhanced biomass production of a novel bio-therapeutic strain Lactobacillus plantarum (AS-14) by developing low cost media cultivation strategy
Journal of Biological Engineering, 2017Co-Authors: Asma Manzoor, Javed Iqbal Qazi, Ikram Ul Haq, Hamid Mukhtar, Akhtar RasoolAbstract:Background Probiotic bacteria are becoming an important tool for improving human health, controlling diseases and enhancing immune responses. The availability of a cost effective cultivation conditions has profound effect on the efficiency and role of probiotic bacteria. Therefore the current study was conducted with an objective to develop a low cost growth medium for enhancing the biomass production of a bio-therapeutic bacterial strain Lactobacillus plantarum AS-14. In this work the isolation of Lactobacillus plantarum AS-14 bacterial strain was carried out from brinjal using cheese whey as a main carbon source. Moreover, the effect of four other nutritional factors besides cheese whey was investigated on the enhanced cell mass production by using response surface methodology (RSM). Results The best culture medium contained 60 g/l cheese whey, 15 g/l glucose and 15 g/l corn steep liquor in addition to other minor ingredients and it resulted in maximum dry cell mass (15.41 g/l). The second-order polynomial regression model determined that the maximum cell mass production (16.02 g/l) would be obtained at temperature 40°C and pH 6.2. Comparative studies showed that cultivation using cheese whey and corn steep liquor with other components of the selected medium generated higher biomass with lower cost than that of De Man, Rogosa and Sharpe (MRS) medium under similar cultivation conditions (pH 6.2 and temperature 40°C). Conclusion It is evident that the cell biomass of L. Plantarum AS-14 was enhanced by low cost cultivation conditions. Moreover, corn steep liquor and Ammonium Bisulphate were perceived as low-cost nitrogen sources in combination with other components to substitute yeast extract. Of all these factors, cheese whey, corn steep liquor, yeast extract and two operating conditions (temperature and pH) were found to be the most significant parameters. Thus the cost effective medium developed in this research might be used for large-scale commercial application where economics is quite likely important.
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Significantly enhanced biomass production of a novel bio-therapeutic strain Lactobacillus plantarum (AS-14) by developing low cost media cultivation strategy
Journal of biological engineering, 2017Co-Authors: Asma Manzoor, Javed Iqbal Qazi, Ikram Ul Haq, Hamid Mukhtar, Akhtar RasoolAbstract:Probiotic bacteria are becoming an important tool for improving human health, controlling diseases and enhancing immune responses. The availability of a cost effective cultivation conditions has profound effect on the efficiency and role of probiotic bacteria. Therefore the current study was conducted with an objective to develop a low cost growth medium for enhancing the biomass production of a bio-therapeutic bacterial strain Lactobacillus plantarum AS-14. In this work the isolation of Lactobacillus plantarum AS-14 bacterial strain was carried out from brinjal using cheese whey as a main carbon source. Moreover, the effect of four other nutritional factors besides cheese whey was investigated on the enhanced cell mass production by using response surface methodology (RSM). The best culture medium contained 60 g/l cheese whey, 15 g/l glucose and 15 g/l corn steep liquor in addition to other minor ingredients and it resulted in maximum dry cell mass (15.41 g/l). The second-order polynomial regression model determined that the maximum cell mass production (16.02 g/l) would be obtained at temperature 40°C and pH 6.2. Comparative studies showed that cultivation using cheese whey and corn steep liquor with other components of the selected medium generated higher biomass with lower cost than that of De Man, Rogosa and Sharpe (MRS) medium under similar cultivation conditions (pH 6.2 and temperature 40°C). It is evident that the cell biomass of L. Plantarum AS-14 was enhanced by low cost cultivation conditions. Moreover, corn steep liquor and Ammonium Bisulphate were perceived as low-cost nitrogen sources in combination with other components to substitute yeast extract. Of all these factors, cheese whey, corn steep liquor, yeast extract and two operating conditions (temperature and pH) were found to be the most significant parameters. Thus the cost effective medium developed in this research might be used for large-scale commercial application where economics is quite likely important.
