Recovery of indium from indium tin oxide by solvent extraction

Recovery of indium from LCD screen wastes, which contain indium in the form of indium tin oxide (ITO) as the electrode material, is becoming economically and environmentally justified. Indium is a valuable metal and the present work was aimed to recover indium from ITO as the starting material to study the recovery of indium from waste LCD screens by solvent extraction. The apparent rate of dissolution in acidic media is slow requiring six hours for complete dissolution of the ITO sample in 1 M of either H2SO4 or HCl. Complete dissolution in HNO3 took significantly longer. The acid concentration was found to have a major effect on both the amount and rate of leaching allowing some leaching selectivity. Three solvent systems were chosen to study their selectivity for the separation of indium from tin: TBP, D2EHPA and a mixture of both. With either 1 M of TBP or 0.2 M of D2EHPA + 0.8 M of TBP, tin could be selectively extracted from a 1.5 M HCl solution of this metal. D2EHPA extracts both indium and tin from H2SO4 media but indium could be selectively stripped with HCl from the loaded D2EHPA. Based on these results, a scheme for separating and concentrating indium from ITO by solvent extraction is proposed. The scheme includes dissolving ITO into 1 M of H2SO4, then extracting indium and tin to D2EHPA followed by selective stripping of indium into 1.5 M of HCl. With this process, HCl solution containing 12.2 g/L of indium could be achieved

Extraction and separation of nickel and cobalt by Electrostatic Pseudo Liquid Membrane (ESPLIM)

The extraction and separation of nickel and cobalt using Electrostatic Pseudo Liquid Membrane (ESPLlM) was investigated. An ESPLIM reactor was constructed and extraction tests were undertaken to determine the effects of various experimental variables on the extraction and separation of nickel and cobalt. At optimum conditions, devised as a result of this investigation, a nickel/cobalt ratio of 1000 in the raffinate from a synthetic feed solution containing 10,000 ppm nickel and 1000 ppm cobalt was achieved. Separation of nickel and cobalt from a pregnant leach solution (PLS) was achieved in two stages.6 page(s

Effects of drying of cowpea grains on consumer acceptability of moin-moin

A drying test was conducted on wet de-hulled cowpea grains to ascertain the effects of drying at 60oC, 70oC, 80oC, and 90oC on the physico-chemical properties and sensory evaluation (consumer acceptability) of moin-moin from different flours. Chemical analyses were conducted on the flour to ascertain the effect of different levels of drying on the protein, carbohydrate and water binding capacity of the flours. A fifteen member trained panelist was purposively chosen to assess the quality of the moin-moin produced. The results of the analysis revealed that temperature of drying affected the protein, carbohydrate and water binding capacity of cowpea flour. The different drying scenarios also affected the acceptability of moin-moin by consumers. The study showed that moin-moin produced from a 60oC dried cowpea grains was sensorily preferred and accepted by consumers. Key words: drying, cowpea flour, moin-moin, consumer preference Journal of Agriculture and Food Sciences Vol. 4 (2) 2006: pp. 125-13

Assessment of weed infestation and economic returns of maize/cowpea intercrop under different tillage systems in northern Ghana

No Abstract Available Ghana Jnl agric. Sci, Vol.36 2003: 107-11

Economic analysis of commercial seed yam production systems in the sub-humid ecologies of the river niger

Published studies to date have suggested that seed-yam (Dioscorea rotundata) production in Nigeria using minisett (~0.025 kg) technology or an adapted form of the technology using larger setts (0.08 to 0.1 kg) was not profitable. But these studies were often conducted under artificial conditions where labor inputs may have been inflated. This paper describes the results of a questionnaire-based survey designed to explore the economic performance of seed-yam producers in the Ilushi hinterland area of Nigeria, along the western bank of the River Niger. It is the first economic study of this important source of seed yam. Farmers in this area specialize in seed-yam production via two techniques: the use of small whole tubers (0.05 to 0.1 kg) and setts (cut pieces of tuber) of 0.12 to 0.15 kg. Results suggest that seed-yam production is profitable in the area using both systems, with gross margins (revenue - costs) of between Naira 23,395 and 61,375/ha (or US$175 to$458/ha). © 2012 Taylor and Francis Group, LLC

Economic analysis of commercial seed yam production systems in the Subhumid ecologies of the river Niger

Published Online: 17 January, 2012Published studies to date have suggested that seed-yam (Dioscorea rotundata) production in Nigeria using minisett (∼0.025 kg) technology or an adapted form of the technology using larger setts (0.08 to 0.1 kg) was not profitable. But these studies were often conducted under artificial conditions where labor inputs may have been inflated. This paper describes the results of a questionnaire-based survey designed to explore the economic performance of seed-yam producers in the Ilushi hinterland area of Nigeria, along the western bank of the River Niger. It is the first economic study of this important source of seed yam. Farmers in this area specialize in seed-yam production via two techniques: the use of small whole tubers (0.05 to 0.1 kg) and setts (cut pieces of tuber) of 0.12 to 0.15 kg. Results suggest that seed-yam production is profitable in the area using both systems, with gross margins (revenue – costs) of between Naira 23,395 and 61,375/ha (or US$175 to$458/ha)

Options for cogongrass ((Imperata cylindrica) control in white guinea yam (Dioscorea rotundata) and cassava (Manihot esculenta)1

Cogongrass is a serious weed in small-scale farms in the lowland humid zone of West Africa. This study evaluated the response of cogongrass to herbicides and the legume cover crop velvetbean in cassava and white Guinea yam. In 2001/2002, cassava tuber yields and gross returns in treatments that received glyphosate alone were higher than in plots that received fluazifop-P-butyl once. In 2002/2003, treatments that received fluazifop-P-butyl once, glyphosate alone, glyphosate integrated with sowing velvetbean, or hoeing only, had higher cassava tuber yields than other treatments. Gross returns were higher in treatments that received glyphosate followed by sowing velvetbean or those hoed only than in other treatments. Fluazifop-P-butyl applied twice, glyphosate alone, or glyphosate followed by sowing velvetbean reduced cogongrass shoot biomass more than other treatments. Rhizome biomass was lower in plots that received glyphosate alone than in all fluazifop-P-butyl treatments. In 2002, white Guinea yam tuber yields were highest in plots that received glyphosate alone and lowest in plots where fluazifop-P-butyl was applied alone or followed by sowing velvetbean. The highest gross return was obtained in plots that received glyphosate alone while the lowest was obtained in plots that received fluazifop-P-butyl once followed by sowing velvetbean. In 2003, the highest tuber yields and gross returns were from plots that received glyphosate alone, fluazifop-P-butyl alone, or those hoed only. The hoed-only plots had 14 times higher cogongrass shoot biomass and 7 times higher rhizome biomass than other treatments. In both crops, hoeing alone or followed by sowing velvetbean was more costly than chemical control. The highest margin over hoeing was obtained from plots that received glyphosate alone. Sensitivity analysis showed that using glyphosate was more cost effective than fluazifop-P-butyl, even if the cost of the herbicide increased by 100% or the cost of labor decreased by 30%

Farmers perceptions of the speargrass (Imperata cylindrica) problem and its control in the lowland subhumid savannah of Nigeria

Speargrassseverely constraints crop production in the sub-humid lowlands of West Africa. Researchers have identified and demonstrated effectivemanagement techniques but the adoption rate among farmers is still low. Data were collected from 41 communities in Cross River, Kogi and BenueStates in Nigeria using rural rapid appraisal techniques. The objectives were to assess the importance of agriculture in the livelihoods of eachcommunity, identify priority crops, assess perceptions of the speargrass problem, identify existing speargrass control strategies and localinstitutions/farmers with the capacity to implement speargrass control trials. Crop production was the main source of livelihood for all households.The most important crops from the perspectives of both food security and cash sale were cassava and yam, and these were most affected by theweed. Speargrass was the major constraint to crop production because of lack of capital for hiring labour and purchasing inputs, declining soilfertility, bush burning, deforestation, continuous cropping and lack of required skills. Slashing, hand-pulling, burning, deep digging and fallowingwere the most common control methods used by farmers, but these were very labour intensive and ultimately not effective. Farmers assessedspeargrass control measures through labour and cash requirements, material availability, effectiveness, time span to achieve control and cropyields. They rated chemical control most highly. Longer fallow periods and re-afforestation were effective but impractical as pressure on landintensifies from population growth. From the results of this study, we conclude that the use of community-based participatory a pproaches is essential to identify various technologies for combating speargrass

A participatory appraisal of Imperata management strategies for sustainable land use in the subhumid savanna of Nigeria

Increasing spread of Imperata in the sub-humid Savannah of Nigeria has had many neg- ative results threatening the sustainability of the natural resource base and livelihood of farmers. A community-based participatory approach (PA) was conducted to identify cur- rent and alternative technologies for controlling Imperata , which support sustainable land use. The PA involved Imperata infestation mapping, livelihood analysis, wealth ranking, crops and constraint prioritisation as well as farmers' evaluation of control methods. Results of the PA showed that farmers commonly used hand weeding and herbicides as well as fallow and burning. High crop yield, income, type of crop(s) grown, capital, chemi- cal, knapsack and labour availability, knowledge and sustainability criteria were the major determinants for the choice of control technique among different wealth (or resource) cat- egories of farmers. Ensuring household food security and prevailing land ownership rights governed the choice of crops grown as well as investment in land management technolo- gies for sustainable Imperata control. Farmers' evaluation of weed management techniques ranked herbicide as the most effective method of controlling Imperata particularly in maize, cassava and cowpea rotation cropping systems. The combination of Mucuna and hand weeding was second and third was the combination of Mucuna and herbicides. Other methods favoured by farmers included the use of improved cassava that shaded the Imper-ata, fallow and burning as an emergency control method. These methods reduce labour requirements, may increase costs but can contribute to higher income, food availability, and land sustainability. These control methods were the most preferred by resource-poor farmers, but are least likely to be adopted. It will be important to increase local aware- ness about problems associated with bush burning, ensure ready availability of materials, increase farmer knowledge of alternative control options, and increase access to credit. These will enhance improved management of Imperata, providing options for all categories of farmer