In this work, the removal of iron from leach liquors obtained after processing of spent alkaline and zinc-carbon Zn/MnO2 batteries with initial iron ion concentration in the range of 270 to 580mg/L ...has been studied. Solid Na2CO3, ZnO and fine ground waste electrode materials separated from processed Zn/MnO2 batteries were tested as precipitation agents. All used precipitation agents make it possible to remove more than 99% Fe, but electrode materials have been found to be more efficient precipitants at lower pH values. The different course of iron precipitation is probably caused by different solubility of iron compounds formed during the precipitation with various precipitation agents. Precipitates in which iron was present as FeO(OH) originated from processing the leach liquors with Na2CO3 or ZnO Precipitates from processing the leach liquors with electrode materials contained zinc-iron non-stoichiometric oxides, which was established as results of experiments performed with a synthetic solution containing 1.54g/L Fe.
The benefits of potential use of waste materials containing zinc oxide compounds in applications to remove iron from zinc sulphate liquors would include high efficiency, low cost and good filterability of the formed precipitates.
•Zinc liquors contaminated with Fe, Cu, Cd and Ni were obtained.•Iron was hydrolytically removed by Na2CO3, ZnO or waste electrode materials.•All used precipitation agents make possible to remove more than 99.5% Fe.•Electrode materials show better efficiency at lower pH values.•Using electrode materials results in good filterability of iron precipitates.
Dramatically elevated levels of butanol and acetone resulted in higher butanol and total solvent yields for hyperamylolytic Clostridium beijerinckii BA101 relative to the NCIMB 8052 parent strain ...grown in semidefined P2 medium containing either 6% glucose or STAR-DRI 5 maltodextrin. C. beijerinckii BA101 consistently produced on the order of 19 g of butanol per liter in 20-liter batch fermentations. This represents a greater than 100% increase in butanol concentration by the BA101 strain compared to the parent NCIMB 8052 strain. The kinetics of butanol production over time also indicate a more rapid rate of butanol production by BA101 in semidefined P2 medium containing glucose or maltodextrin. The lower levels of butyric and acetic acids produced over the course of the fermentation carried out by BA101 are consistent with an enhanced capacity for uptake and recycling of these acids. C. beijerinckii BA101 appears to more completely utilize carbohydrate compared to the 8052 strain. Carbon balance following fermentation by C. beijerinckii 8052 and BA101 indicates that sufficient carbon is available for the twofold increase in butanol concentration observed during BA101 fermentations. C. beijerinckii BA101 also has superior solvent production capacity during continuous culture fermentation in P2 medium containing 6% glucose. Volumetric solvent yields of 0.78 and 1.74 g/liter/h for BA101 and 0.34 and 1.17 g/liter/h for NCIMB 8052 were obtained at dilution rates of 0.05 and 0.20 h-1, respectively. No drift towards acid synthesis (strain degeneration) was observed for up to 200 h (d = 0.05 h-1) and 100 h (d = 0.20 h-1)
Rubidium was recovered from lithium-containing solution from processing zinnwaldite, (KAl(Fe,Li)(Si3Al)O10F2), concentrate after Li2CO3 crystallization as a mixture of rubidium and potassium alums ...(RbAl(SO4)2.12H2O and KAl(SO4)2.12H2O). The course of individual reactions aiming at rubidium alum separation from carbonated solutions containing potassium as a main contaminant was studied on synthetic solutions. Before the alum precipitation, the original carbonated solution was converted to sulphate solution. Rubidium recovery efficiency at least 95% was achieved if the amount of the precipitation agent (Al2(SO4)3) ranged between 3.5 and 4.0 multiples of stoichiometric amount related to rubidium concentration in the processed solution. Under such conditions, precipitates obtained contain between 4.10 and 3.62% Rb and from 6.02 to 6.25% K and consist of on average 24% rubidium alum and 75% potassium alum.
► Rubidium was recovered from lithium solution after zinnwaldite processing. ► Li2CO3 was separated from carbonated liquor during fractional crystallization. ► Mother solution was converted to sulphate solution. ► Rubidium and potassium alums were obtained during Al2(SO4)3 precipitation.
This work presents a methodology to design an SSL system for reliability. An LED lamp is thermally characterised and its model thermally simulated, indicating that the LED board (FR4 board with ...thermal vias, copper tracks and LED package) is the thermally most stressed part. Therefore, a thermo-mechanical analysis is performed from a detailed LED board model to study reliability and lifetime limits, using thermal boundary conditions deduced from the thermal simulation of the whole LED lamp. Based on this analysis the weakest spots are identified as the metal vias in the LED package and the interconnection area between the LED package and copper tracks on the FR4 board.
To improve the economic competitiveness of the acetone/butanol/ethanol fermentation process, glucose/corn steep water (CSW) medium was used on a pilot scale for the production of solvents. The ...production of butanol by the Clostridium beijerinckii NCIMB 8052 parent strain and the solvent-hyperproducing BA101 mutant was compared. In a 20-l fermentation using 5% glucose/CSW medium, C. beijerinckii 8052 produced 8.5 g butanol/l and 5 g acetone/l, while C. beijerinckii BA101 produced 16 g butanol/l and 7.5 g acetone/l. Further studies were carried out on a larger scale using an optimized 6% glucose/CSW medium. In a 200-l pilot-scale fermentor, C. beijerinckii 8052 produced 12.7 g butanol/l and 6 g acetone/l following 96 h of fermentation. C. beijerinckii BA101 produced 17.8 g/l and 5.5 g/l butanol and acetone respectively, following 130 h of fermentation. These results represent a 40% increase in final butanol concentration by the C. beijerinckii BA101 mutant strain when compared to the 8052 parent strain. The total solvents (acetone, butanol, and ethanol) produced by C. beijerinckii NCIMB 8052 and BA101 in a 200-l fermentation were 19.2 g/l and 23.6 g/l respectively. This is the first report of pilot-scale butanol production by the solvent-hyperproducing C. beijerinckii BA101 mutant employing an inexpensive glucose/CSW medium.
This work presents a comparison of various LED board technologies from thermal, mechanical and reliability point of view provided by an accurate 3-D modelling. LED boards are proposed as a possible ...technology replacement of FR4 LED boards used in 400 lumen retrofit SSL lamps. Presented design methodology can be used for other high power SSL lamp designs. The performance of new LED board designs were evaluated by numerical modeling. Modeling methodology was proven by measurement on reference FR4 LED board. Thermal performance was compared by extracting of LED boards thermal resistances and thermal stress has been inspected considering the widest temperature operating range according to standards (−40 to +125°C). Thermo-mechanical and reliability analysis have been performed to study parameters of each LED board technology, using thermal boundary conditions extracted from the thermal simulation of a whole LED lamp. Elastic–plastic analysis with temperature dependent stress–strain material properties has been performed. The objective of the work is to optimize not only the thermal management by thermal simulation of LED boards, but also to find potential problems from mechanical failure point of view and to present a methodology to design SSL LED boards for reliability.
Corn steep water (CSW) medium (1.6% solids plus 6% glucose) was evaluated for growth and butanol production by Clostridium beijerinckii NCIMB 8052 wild-type and hyper-amylolytic, ...hyper-butanol-producing mutant strain BA101. CSW alone was not a suitable substrate, whereas addition of glucose supported growth and butanol production by both strains. In a batch-scale fermentation using an optimized 6% glucose-1.6% solids CSW medium, C. beijerinckii NCIMB 8052 and strain BA101 produced 10.7 g L-1 and 14.5 g L-1 of butanol, respectively. The total solvents (acetone, butanol, and ethanol) produced by C. beijerinckii NCIMB 8052 and strain BA101 were 14 g L-1 and 20 g L-1, respectively. Initial fermentation in small-scale flasks containing 6% maltodextrin-1.6% solids concentration CSW medium resulted in 6 g L-1 and 12.6 g L-1 of butanol production by C. beijerinckii NCIMB 8052 and strain BA101, respectively. CSW can serve as an economic source of nitrogen, vitamins, amino acids, minerals, and other nutrients. Thus, it is feasible to use 6% glucose-1.6% solids CSW medium in place of semi-defined P2 medium
The use of a standard two-tier neurotoxicity screening procedure in the context of risk assessment is exemplified. Testing of a new pyrethroid in rats addressed the following sequence of questions: ...Does the substance evoke neurotoxic symptoms in sublethal doses? Do these symptoms reflect a primary neurotropic action? What are the dynamic characteristics of injury, the clinical profile of effect, and the relative potency of the tested substance compared to similar compounds? - The testing protocol is an animal analogue of a systematic neurological and psychological examination in man. First tier tests (structured observation, motor activity measurement, simple neurological examination) were applied after the first dose, during repeated dosing phase and in the restitution phase. Facultative tests for the second-tier examination (motor activity pattern, learning/retention test, evoked potentials, dynamic motor performance) were selected on the basis of effects revealed by the first-tier testing. Supermethrin evoked acute neurotoxicity in sublethal doses, ranging from 1/30 to 1/15 of LD50. The clinical pattern was similar to other cyano-substituted pyrethroids. Behavioural inhibition was transient and complete tolerance to it developed after 4-week repeated dosing. No indications of long-lasting changes in neuronal excitability or in learning and memory processes were found. Ataxia and excitomotoric phenomena dominated both the acute and the subchronic picture. Marked and persistent motor disturbances, including symptoms of lower motoneuron injury, were limited to individual animals of the highest, near-lethal dose group (27 mg-kg-1). Compared to lambda-cyhalothrin, the effects of supermethrin were 2 to 3 times weaker, disappeared more rapidly, cumulated less, and had higher tendency to tolerance.
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