This paper outlines the synthesis of maghemite from raw iron waste obtained in an iron mill dumpsite around Ogun state, Nigeria. Magnetite was synthesized from the ferrous precursor obtained by digesting the iron wast...This paper outlines the synthesis of maghemite from raw iron waste obtained in an iron mill dumpsite around Ogun state, Nigeria. Magnetite was synthesized from the ferrous precursor obtained by digesting the iron waste with concentrated H<sub>2</sub>SO<sub>4</sub>. Transformation of magnetite to maghemite was done by heating the magnetite obtained in an oven at 200°C. To determine the absorption capacity of the synthesized maghemite sample, a stock solution of As(III) was used for the absorption. Absorption spectrum shows higher absorption of γ-Fe<sub>3</sub>O<sub>4</sub> at higher concentration of As(III). Maximum absorption obtained is 14 mg/g. Estimated yield of γ-Fe<sub>3</sub>O<sub>4</sub> was 32%;however a low, further study promises to improve the yield value. The study shows γ-Fe<sub>3</sub>O<sub>4</sub> to be a good absorbent for heavy metals.展开更多
Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil a...Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil and groundwater. The reuse of these wastes as raw materials for the production of advanced materials is a viable way both to overcome the environmental impact and to reduce the disposal costs,proposing new technologically advanced materials. This work aims to simulate these interesting glassceramics by using glass cullet coming from recycled municipal waste and high amount of iron（III） oxide（from 25 wt% to 50 wt%）, the prevalent component of steel waste. The oxide was mixed with glass cullet and vitrified. The samples composition and the microstructure were investigated by scanning electron microscopy（SEM）, and X-ray diffraction（XRD） was used to evaluate the nature of the crystalline phases.The chemical stability of the materials, in terms of ionic release into saline solution, was assessed. The electrical behavior of the samples was also investigated by varying the iron ions content and controlling the crystallization process. It is possible to obtain chemically stable materials with a nearly semiconducting behavior.展开更多
The removal of As（III） and As（V） from aqueous solution was investigated using waste cast iron, which is a byproduct of the iron casting process in foundries. Two types of waste cast iron were used in the experimen...The removal of As（III） and As（V） from aqueous solution was investigated using waste cast iron, which is a byproduct of the iron casting process in foundries. Two types of waste cast iron were used in the experiment： grind precipitate dust （GPD） and cast iron shot （CIS）. The X-ray diffraction analysis indicated the presence of Fe~ on GPD and CIS. Batch experiments were performed under different concentrations of As（III） and As（V） and at various initial pH levels. Results showed that waste cast iron was effective in the removal of arsenic. The adsorption isotherm study indicated that the Langmuir isotherm was better than the Freundlich isotherm at describing the experimental result. In the adsorption of both As（III） and As（V）, the adsorption capacity of GPD was greater than CIS, mainly due to the fact that GPD had higher surface area and weight percent of Fe than CIS. Results also indicated the removal of As（III） and As（V） by GPD and CIS was influenced by the initial solution pH, generally decreasing with increasing pH from 3.0 to 10.5. In addition, both GPD and CIS were more effective at the removal of As（III） than As（V） under given experimental conditions. This study demonstrates that waste cast iron has potential as a reactive material to treat wastewater and groundwater containing arsenic.展开更多
The extrartion of aluminum from coal mining waste(CMW) is an important industrial process.The two major problems in applications are low aluminum dissolution efficiency and high iron content in the raw material,which ...The extrartion of aluminum from coal mining waste(CMW) is an important industrial process.The two major problems in applications are low aluminum dissolution efficiency and high iron content in the raw material,which affect the quantity and quality of products.To improve the aluminum recovery process,the leaching kinetics of CMW with hydrochloric acid was studied.A shrinking core model was used to investigate aluminum and iron dissolution kinetics.Based on the kinetic characteristics,a process for recovering aluminum was proposed and tested experimentally.It is found that the aluminum leaching reaction is controlled by surface reaction at low temperatures(40-80℃) and by diffusion process at higher temperatures(90-106℃).The iron dissolution process is dominated by surface reaction at 40-100℃.The results show that iron could be dissolved or separated by concentrated hydrochloric acid.Fine grinding will improve aluminum dissolution significantly.展开更多
Traditional cement-based materials are being gradually replaced by nanomodified cement-based materials because the traditional materials cannot meet the production needs of modern society.Nano-iron boride(nano-FeB)is ...Traditional cement-based materials are being gradually replaced by nanomodified cement-based materials because the traditional materials cannot meet the production needs of modern society.Nano-iron boride(nano-FeB)is a high-performance nanomaterial prepared from waste iron powder during construction.Its one-dimensional structure is similar to that of carbon nanotubes,which makes it a potential candidate for nano-reinforcement materials.In this paper,the effects of different contents of recycled nano-FeB(0%,0.05%,0.075%,and 0.1 wt.%,based on cement weight)on the mechanical properties and electrical conductivity of cement mortar were studied.The results showed that the mechanical properties of the composite cement mortar were improved with the addition of nano-FeB.When the content of nano-FeB was 0.075%,the 28 d compressive strength and flexural strength of the composite cement mortar increased by 60.2%and 42.1%,respectively.In addition,a 0.075%nano-FeB content favorably improved the conductivity of cement mortar.Compared with that of the control group,the volume resistivity of the composite cement mortar decreased by one order of magnitude.展开更多
文摘This paper outlines the synthesis of maghemite from raw iron waste obtained in an iron mill dumpsite around Ogun state, Nigeria. Magnetite was synthesized from the ferrous precursor obtained by digesting the iron waste with concentrated H<sub>2</sub>SO<sub>4</sub>. Transformation of magnetite to maghemite was done by heating the magnetite obtained in an oven at 200°C. To determine the absorption capacity of the synthesized maghemite sample, a stock solution of As(III) was used for the absorption. Absorption spectrum shows higher absorption of γ-Fe<sub>3</sub>O<sub>4</sub> at higher concentration of As(III). Maximum absorption obtained is 14 mg/g. Estimated yield of γ-Fe<sub>3</sub>O<sub>4</sub> was 32%;however a low, further study promises to improve the yield value. The study shows γ-Fe<sub>3</sub>O<sub>4</sub> to be a good absorbent for heavy metals.
文摘Wastes deriving from steel industry, containing large amounts of iron oxides and heavy metals, when collected in landfills are subjected to atmospheric agents, with consequent release of toxic substances in the soil and groundwater. The reuse of these wastes as raw materials for the production of advanced materials is a viable way both to overcome the environmental impact and to reduce the disposal costs,proposing new technologically advanced materials. This work aims to simulate these interesting glassceramics by using glass cullet coming from recycled municipal waste and high amount of iron（III） oxide（from 25 wt% to 50 wt%）, the prevalent component of steel waste. The oxide was mixed with glass cullet and vitrified. The samples composition and the microstructure were investigated by scanning electron microscopy（SEM）, and X-ray diffraction（XRD） was used to evaluate the nature of the crystalline phases.The chemical stability of the materials, in terms of ionic release into saline solution, was assessed. The electrical behavior of the samples was also investigated by varying the iron ions content and controlling the crystallization process. It is possible to obtain chemically stable materials with a nearly semiconducting behavior.
基金supported by the Brain Korea 21 of SafeSustainable Infrastructure Research Group,Seoul National University
文摘The removal of As（III） and As（V） from aqueous solution was investigated using waste cast iron, which is a byproduct of the iron casting process in foundries. Two types of waste cast iron were used in the experiment： grind precipitate dust （GPD） and cast iron shot （CIS）. The X-ray diffraction analysis indicated the presence of Fe~ on GPD and CIS. Batch experiments were performed under different concentrations of As（III） and As（V） and at various initial pH levels. Results showed that waste cast iron was effective in the removal of arsenic. The adsorption isotherm study indicated that the Langmuir isotherm was better than the Freundlich isotherm at describing the experimental result. In the adsorption of both As（III） and As（V）, the adsorption capacity of GPD was greater than CIS, mainly due to the fact that GPD had higher surface area and weight percent of Fe than CIS. Results also indicated the removal of As（III） and As（V） by GPD and CIS was influenced by the initial solution pH, generally decreasing with increasing pH from 3.0 to 10.5. In addition, both GPD and CIS were more effective at the removal of As（III） than As（V） under given experimental conditions. This study demonstrates that waste cast iron has potential as a reactive material to treat wastewater and groundwater containing arsenic.
基金Supported by the National High Technology Research and Development Program of China(2011AA06A103)the National Natural Science Foundation of China(21306109)
文摘The extrartion of aluminum from coal mining waste(CMW) is an important industrial process.The two major problems in applications are low aluminum dissolution efficiency and high iron content in the raw material,which affect the quantity and quality of products.To improve the aluminum recovery process,the leaching kinetics of CMW with hydrochloric acid was studied.A shrinking core model was used to investigate aluminum and iron dissolution kinetics.Based on the kinetic characteristics,a process for recovering aluminum was proposed and tested experimentally.It is found that the aluminum leaching reaction is controlled by surface reaction at low temperatures(40-80℃) and by diffusion process at higher temperatures(90-106℃).The iron dissolution process is dominated by surface reaction at 40-100℃.The results show that iron could be dissolved or separated by concentrated hydrochloric acid.Fine grinding will improve aluminum dissolution significantly.
基金Financial support from the National Natural Science Foundation of China under the grants of 51578477 and 51708403the Key Research and Development Project of Hebei Province under the grant of 19211505D,and the China Postdoctoral Science Foundation under the grants of 2018T110200 and 2018M640236 is gratefully acknowledged.
文摘Traditional cement-based materials are being gradually replaced by nanomodified cement-based materials because the traditional materials cannot meet the production needs of modern society.Nano-iron boride(nano-FeB)is a high-performance nanomaterial prepared from waste iron powder during construction.Its one-dimensional structure is similar to that of carbon nanotubes,which makes it a potential candidate for nano-reinforcement materials.In this paper,the effects of different contents of recycled nano-FeB(0%,0.05%,0.075%,and 0.1 wt.%,based on cement weight)on the mechanical properties and electrical conductivity of cement mortar were studied.The results showed that the mechanical properties of the composite cement mortar were improved with the addition of nano-FeB.When the content of nano-FeB was 0.075%,the 28 d compressive strength and flexural strength of the composite cement mortar increased by 60.2%and 42.1%,respectively.In addition,a 0.075%nano-FeB content favorably improved the conductivity of cement mortar.Compared with that of the control group,the volume resistivity of the composite cement mortar decreased by one order of magnitude.
