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1
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Influence of physicochemical parameters on stability and performance of biosupported Pd nanocatalysts

100%
De Corte S., Hennebel T., Segers J., Van Nevel S., Verschuere S., Verstraete W., Boon N.
Nanomaterials and the Environment
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2013
|
vol. 1
31-39
EN
Sustainable production methods for catalytic palladium (Pd) nanoparticles are currently being investigated due to their increasing use, limited availability and price volatility. The bio-palladium (bio-Pd) method uses bacteria as a producer and carrier of Pd nanoparticles. In this method, Pd leaching results in economical loss and environmental risk. In this study we therefore investigate the influence of different parameters on the leaching process: temperature (4-21°C), medium (H2O or mineral medium), pH (1–12), atmosphere (air, O2, N2, H2) and bacterial carrier. We show leaching is an important phenomenon for biosupported Pd: 20% of the Pd was released at 21°C in water after 100 days. Minimal leaching occurred at lower temperatures, low pH and in an isotonic medium. Up to 5 times more leaching was observed under anaerobic conditions (H2 or N2 atmosphere) than under aerobic conditions (O2 or air atmosphere). The producer/carrier Cupriavidus metallidurans leached up to 5% zerovalent Pd compared with 20% in Shewanella oneidensis. No loss of catalytic activity due to leaching was observed when the leachate remained in the reaction medium. This paper shows for the first time that release of Pd nanoparticles from the bacterial carrier of bio-Pd can be significant particularly under anaerobic conditions, at high temperature or high pH.
2
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ANFIS based prediction of the aluminum extraction from boehmite bauxite in the Bayer process

88%
Mihajlović I., Đurić I., Živković Ž.
Polish Journal of Chemical Technology
|
2014
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vol. 16
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issue 1
103-109
EN
This paper presents the results of nonlinear statistical modeling of the bauxite leaching process, as part of Bayer technology for alumina production. Based on the data, collected during the year 2011 from the industrial production in the alumina factory Birač, Zvornik (Bosnia and Herzegovina), nonlinear statistical modeling of the industrial process was performed. The model was developed as an attempt to define the dependence of the Al2O3 degree of recovery as a function of input parameters of the leaching process: content of Al2O3, SiO2 and Fe2O3 in the bauxite, as well as content of Na2Ocaustic and Al2O3 in the starting sodium aluminate solution. As the statistical modeling tool, Adaptive Network Based Fuzzy Inference System (ANFIS) was used. The model, defined by the ANFIS methodology, expressed a high fitting level and accordingly can be used for the efficient prediction of the Al2O3 degree of recovery, as a function of the process inputs under the industrial conditions.
3
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Evaluation of Selected Physical and Chemical Soil Properties and their Management for Arable Crop Production in Southern Adamawa State

88%
Gisilanbe S. A., Barnabas I. M., Iheka W., Garpiya B. T.
World News of Natural Sciences
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2019
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vol. 25
44-60
EN
Soil is essential for food production, and there is need practice sustainable soil management. This study was aimed to evaluate physical and chemical properties of soils and their management in three farming communities; Sangasumi (SGS), Gangkoen (GGK) and Gangbuen (GGB) of Southern Adamawa State, Nigeria. The intent is to encourage optimum land use planning and increase the efficiency in the use of soil resources. In the work, a digital Terrain Model (DTM) was generated from the map of the study area, and three elevation ranges were identified; 660-780m - representing the upper-slope in SGS, 540-660m - representing the middle-slope in GGK and 420-540m - representing the lower-slope in GGB, respectively. Three slope positions were delineated using the Geographic Information System (GIS) and their coordinates were obtained by means of a Handheld Geographic Positioning System (GPS). Three profile pits were dug on each of the locations and soil samples were collected in each of the identified horizon of the pits. Standard laboratory procedures were then used to determine soil physical and chemical properties. Herein, results for particle size analysis indicated that the soils were predominantly sand, ranging between 51% to 91% across the pedons and %sand was positively correlated with bulk density. Moreover, soil pH in each sample was slightly acidic to neutral (6.1-6.5 to 6.6-7.3), while organic carbon and total nitrogen levels were low (<1%, <0.15%) and available phosphorus levels were medium (10-20ppm). In contrast, magnesium was high (>1), sodium recorded up to 0.60cmol/kg, potassium was also high (>0.3) and %base saturation were generally medium to high (50-80 to >80). Results suggest the soils have potentials for arable farming. However, soil erosion hazards had affected parts of the fields; this lead to reduction in soil fertility and crop yields. Addition of organic and inorganic fertilizers and control of soil erosion will greatly improve soil fertility losses and increase crop yields.
4
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Extraction and optimization of Mucuna pruriens for dyeing of leather

88%
Sundari N.
Polish Journal of Chemical Technology
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2015
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vol. 17
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issue 2
57-63
EN
The present study reports on the leaching of natural pigment from Mucuna pruriens for dyeing of chrome tanned leather samples. The experiments were performed at temperature (30-70°C), time (30-90 min), feed to solvent ratio (1:3-1:7) and particle size (0.25-0.75 mm) using ethanol as solvent. The influence of process variables on percentage yield has been studied and the conditions were optimized using Box-Behnken design. The optimized conditions for intensified extraction was found to occur at a temperature of 60°C, extraction time of 1 hr, for a feed to solvent ratio of 1:5 and 0.75 mm particle size. The % yield under optimized conditions was found to be 47%. The extraction results were found to agree well with the statistical model (R2 = 0.9740). The colouring ability of extracted dye has been tested on wet blue goat leathers. The dyed leather exhibited a better colour value, strength and fastness properties as inferred from reflectance and visual assessment tests.
5
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Preparation and characterization of high specific surface area Mn3O4 from electrolytic manganese residue

88%
Peng T., Xu L., Chen H.
Open Chemistry
|
2010
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vol. 8
|
issue 5
1059-1068
EN
Mn3O4 powders have been produced from Electrolytic Manganese Residue (EMR). After leaching of EMR in sulfuric acid, MnSO4 solution containing various ions was obtained. Purifying the solution obtained and then adding aqueous alkali to the purified MnSO4 solution, Mn(OH)2 was prepared. Two methods were employed to produce Mn3O4. One way was oxidation of Mn(OH)2 in aqueous phase under atmosphere pressure to obtain Mn3O4. The other way was roasting Mn(OH)2 precursors in the range of 500°C to 700°C. The prepared samples were investigated by using several techniques including X-ray powder diffraction (XRD), Fourier Transformation Infra-Red (FTIR) spectra, and Brunauer-Emmett-Teller (BET) specific surface area instrument. Particle distribution and magnetic measurements were carried out on laser particle size analyzer, vibrating sample magnetometer (VSM). Through XRD, FTIR and determination of total Mn content (TMC), the products prepared were confirmed to be a single phase Mn3O4. BET specific surface areas can reach to 32 m2 g−1. The results indicated that products synthesized by aqueous solution oxidation method had higher specific surface areas and smaller particle size than those prepared by means of roasting. However the products prepared using the above two methods showed no obvious differences in magnetic property. [...]
6
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Alkali roasting of bomar ilmenite: rare earths recovery and physico-chemical changes

88%
Sanchez-Segado S., Lahiri A., Jha A.
Open Chemistry
|
2015
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vol. 13
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issue 1
EN
In this work, the alkali roasting of ilmenite (FeTiO3) is presented as a process route for integrated beneficiation of the mineral for rutile-rich phase and rare earth oxides; the latter is released as a consequence of physical changes in the ilmenite matrix, during the water leaching after roasting. The oxidative alkali roasting transforms ilmenite mineral into water-insoluble alkali titanate and water-soluble ferrite. After roasting the insoluble alkali titanate is separated from rare-earth oxide mixture in colloidal form and water-soluble ferrite. Further leaching of alkali titanate is carried out with oxalic (0.3M) and ascorbic (0.01M) acid solution which removes the remaining Fe2+ ions into the leachate and allows precipitation of high-purity synthetic rutile containing more than 95% TiO2. Iron is removed as iron oxalate. The physico-chemical changes occurred during the roasting and leaching processes are reported by comparing the role of alkali on the roasting process and product morphologies formed.
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