Many nanoparticles have been created over the last few decades using a variety of techniques and used to develop environmental technology, including water treatment, the detection of persistent contaminants, and soil ...Many nanoparticles have been created over the last few decades using a variety of techniques and used to develop environmental technology, including water treatment, the detection of persistent contaminants, and soil and water remediation. The studies of alternative inputs for nanoparticle production as well as the use of green synthesis techniques are driven by the field of materials science and engineering’s growing interest in increasing the sustainability of the processes involved in their production. In this paper, we begin by providing an overview of the fundamental principles of producing nanoparticles from different sources, such as plastic, electronic, metal, and industrial waste. We elaborate on key facts of waste identification as a workable input for the treatment and recovery of metal and carbon-based nanoparticles. We next go over several controlling factors that play a role in creating nanoparticles, pointing out probable conclusions as we go. Then, we show some instances of waste-derived nanoparticles used in a proof-of-concept experiment of technology for applications in water quality and safety. Before scaling up production and implementing waste-derived nanoparticles, there are several present problems from the toxicological and life-cycle perspectives that must be taken into account.展开更多
Stormwater runoff has become an important source of surface water pollution. Bioretention, a low impact development measure in urban stormwater management, has been proven to be effective in the removal of pollutants ...Stormwater runoff has become an important source of surface water pollution. Bioretention, a low impact development measure in urban stormwater management, has been proven to be effective in the removal of pollutants from stormwater runoff, with appropriate bioretention media. In this study, construction wastes were selected as bioretention media to remove heavy metals from stormwater runoff. Static and dynamic adsorption batch experiments were carried out to investigate the adsorption of heavy metals in simulated stormwater runoff system with construction wastes in different particle sizes. The experimental results show that the pseudo-secondorder kinetic model characterizes the adsorption process and the adsorption equilibrium data are well described by Freundlich isotherm model. The construction wastes used can remove heavy metals from stormwater runoff effectively, with their average removal rates all more than 90%. The particle size of construction wastes greatly influences the equilibrium time, rate and adsorption capacity for heavy metals.展开更多
The geopolymer samples were prepared with smelting waste slag of non-ferrous metal as the raw material and water glass as the activator. The effect of modulus of water glass and water binder ratio on the compressive s...The geopolymer samples were prepared with smelting waste slag of non-ferrous metal as the raw material and water glass as the activator. The effect of modulus of water glass and water binder ratio on the compressive strength was studied. The results show that the strength of the geopolymer activated by water glass with modulus of 1.1 and water binder ratio of 0.28 can maintain an increasing trend in the 90 curing days. Through the analyses with XRD, SEM(EDS), and FTIR, the main reaction products are found to be geopolymer gels, which bond the crystalline minerals to provide strength. The molecular chains of amorphous phase in slag become shorter after depolymerization-polycondensation.展开更多
Research conducted on ceramic materials has been investigating the incorporation of solid waste into their formulations,driven by the proper disposal of such waste and the reduction of negative environmental impacts.T...Research conducted on ceramic materials has been investigating the incorporation of solid waste into their formulations,driven by the proper disposal of such waste and the reduction of negative environmental impacts.This study analyzed the effects of adding aluminum powder residue to the physical properties of ceramic masses with the aim of obtaining new formulations for ceramic tiles.The aluminum residue and the standard mass for ceramic tile production were chemically characterized and homogenized to obtain new formulations with the incorporation of 4%,6%,8%,and 10%aluminum powder in the ceramic mass.The specimens were uniaxially pressed and sintered at a temperature of 1,200°C for 2 h,undergoing three different temperatures(100°C,400°C,and 650°C)for 30 min each.They were evaluated for WA(water absorption),RLq(linear shrinkage),SEM(scanning electron microscopy),and TRF(flexural strength)modulus.The results demonstrate that the addition of aluminum powder residue is feasible in the proposed formulations(4%,6%,8%,and 10%),as they enhance the mechanical properties of the ceramics compared to the formulation with 0%residue,at a sintering temperature of 1,200°C.展开更多
IBC Advanced Technologies' Molecular Recognition Technology(MRT) products,trade named SuperLig,selectively and rapidly bind with target metal ions to remove them from solution.The MRT process can produce a high pu...IBC Advanced Technologies' Molecular Recognition Technology(MRT) products,trade named SuperLig,selectively and rapidly bind with target metal ions to remove them from solution.The MRT process can produce a high purity separation product of maximum added value at low cost.In this paper,applications of MRT in the precious metals industry,including selective commercial separations involving Au,Pd,Pt,Rh,and Ru,are described and discussed.Application of MRT to the analytical determination of precious metals is presented.Potential use of MRT in recovering precious metals from end-of-life(EOL) products is discussed.展开更多
This study compared the physicochemical parameters and heavy metal levels in soil samples from selected anthropogenic sites within Enugu metropolis, Enugu State, Nigeria using standard analytical methods. Soil samples...This study compared the physicochemical parameters and heavy metal levels in soil samples from selected anthropogenic sites within Enugu metropolis, Enugu State, Nigeria using standard analytical methods. Soil samples at depths (0 - 20 cm) and (20 - 40 cm) were collected from waste dump sites, metal scrap dumps, fuel filling stations and auto-mechanic workshops and analyzed for physicochemical characteristics and heavy metal levels. Atomic absorption spectrophotometer was used for heavy metal determination while conventional analytical methods were employed for physicochemical parameters evaluation of the soil samples. At soil depths 0 - 20 cm and 20 - 40 cm the respective mean range of pH, electrical conductivity, organic matter and organic carbon contents in the soil samples were, 6.33 - 6.74, 101.46 - 123.21 <em>μ</em>S/cm, 6.41% - 8.35% and 13.73% - 16.14% for auto-mechanic workshops;6.92 - 7.43, 56.46 - 60.02 <em>μ</em>S/cm, 1.53% - 2.20% and 11.93% - 12.60% for fuel filling stations;7.14 - 7.84, 70.81 - 77.71 <em>μ</em>S/cm, 3.81% - 4.12% and 8.57% - 9.24% for metal scrap dumps;6.54 - 6.81, 94.40 - 100.71 <em>μ</em>S/cm, 8.83% - 10.75% and 18.26% - 20.81% for waste dump sites. The pH of the top soil samples from auto-mechanical workshop was below the WHO recommended limits for agricultural purposes. The physic-chemical characteristics of the soil samples decreased with soil depths indicating therefore that anthropogenic activities greatly influence the soil characteristics at the top soils than the sub-soils. The electrical conductivity values of top and sub-soil samples from the studied auto-mechanical workshops were above the recommended limits. At soil depths 0 - 20 cm and 20 - 40 cm, the respective mean range of Zn, Pb and Cd in the soil samples were 17.29 - 19.16 <em>μ</em>g/g, 0.704 - 0.96 <em>μ</em>g/g and 0.26 - 0.33 <em>μ</em>g/g for auto-mechanic workshops;4.13 - 4.88 <em>μ</em>g/g, 0.21 - 0.32 <em>μ</em>g/g and 0.03 - 0.11 <em>μ</em>g/g for fuel filling stations;30.02 - 36.11 <em>μ</em>g/g, 0.43 - 0.48 <em>μ</em>g/g and 0.15 - 0.19 <em>μ</em>g/g for metal scrap dumps;9.30 - 10.84 <em>μ</em>g/g, 0.53 - 0.60 <em>μ</em>g/g and 0.38 - 0.45 <em>μ</em>g/g for waste dump sites. The mean levels of Pb in soil samples from mechanic workshops and waste dump sites were above the recommended permissible limits for agricultural purposes. The study therefore indicated that these sites (auto-mechanic workshops and waste dump sites) could be major sources of Pb pollution to nearby farmlands, streams and the general environment. Plants grown on or around these sites may not produce high yields and could be severely contaminated with heavy metals which portend health danger to food consumers within the environment.展开更多
The fly ash from two municipal solid waste incineration plants in Shanghai was treated by the self-developed organic composite chelating agent. The results indicated that the stabilization effect of Pb in the fly ash ...The fly ash from two municipal solid waste incineration plants in Shanghai was treated by the self-developed organic composite chelating agent. The results indicated that the stabilization effect of Pb in the fly ash by the composite chelating agent was the best,and the proportions of its easily leaching form in the two kinds of fly ash decreased from 29. 60% and 27. 49% to 3. 05% and 0. 29% respectively. The leaching toxicity of stabilized fly ash was lower than the limits of Standard for Pollution Control on the Landfill Site of Municipal Solid Waste( GB 16889- 2008),so it can be landfilled separately in the landfill site of municipal solid waste.展开更多
Knowledge about heavy metal release from industrial solid wastes(ISWs) is crucial for better management of their environmental risks. This study was conducted to investigate the effect of organic and inorganic acids, ...Knowledge about heavy metal release from industrial solid wastes(ISWs) is crucial for better management of their environmental risks. This study was conducted to investigate the effect of organic and inorganic acids, clay minerals, and nanoparticles(NPs) on the release of heavy metals from sugar factory waste, ceramic factory waste, leather factory waste, and stone cutting waste. The influence of the extractants on heavy metal release from these ISWs was in the following descending order: citric acid > oxalic acid > nitric acid≥ sulfuric acid > Ca Cl2. Addition of clay minerals and NPs as adsorbents decreased heavy metal release, which was significantly lower in NP-treated wastes than in the clay mineral-treated wastes. On the other hand, the presence of organic and inorganic acids increased heavy metal adsorption by NPs and clay minerals. These results suggest that NPs can be applied successfully in waste remediation,and organic and inorganic acids play an important role in the removal of heavy metals from the studied adsorbents.展开更多
Bottom ash is an inevitable by-product fi'om municipal solid waste (MSW) incineration plants. Recycling it as additives for cement production is a promising disposal method. However, the heavy metals and chlorine a...Bottom ash is an inevitable by-product fi'om municipal solid waste (MSW) incineration plants. Recycling it as additives for cement production is a promising disposal method. However, the heavy metals and chlorine are the main limiting factors because of the potential environmental risks and corrosion of cement kilns. Therefore ,investigating heavy metal and chlorine characteristics of bottom ash is the significant prerequisite of its reuse in cement industries. In this study, a correlative analysis was conducted to evaluate the effect of the MSW components and collection mode on the heavy metal and chlorine characteristics in bottom ash. The chemical speciation of insoluble chlorine was also investigated by synchrotron X-ray diffraction analysis. The results showed that industrial waste was the main source of heavy metals, especially Cr and Pb, in bottom ash. The higher contents of plastics and kitchen waste lead to the higher chlorine level (0.6 wt.%-0.7 wt.%) of the bottom ash. The insoluble chlorine in the MSW incineration bottom ash existed primarily as AlOCl, which was produced under the high temperature (1250℃) in incinerators.展开更多
The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2+and Zn2+in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was...The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2+and Zn2+in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients(above 0.99 for both metal ions) and insignificant lack of fit(p = 0.0838 and 0.0782 for Pb2+and Zn2+, respectively). Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation(between –NH2,-CN and metal ions) and ion-exchange(between –COOH and metal ions). The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.展开更多
Currently, increasing amounts of end-of-life (EoL) electronic products are being generated due to their reduced life spans and the unavailability of suitable recycling technologies. In particular, waste printed circ...Currently, increasing amounts of end-of-life (EoL) electronic products are being generated due to their reduced life spans and the unavailability of suitable recycling technologies. In particular, waste printed circuit boards (PCBs) have become of global concern with regard to environmental issues because of their high metal and toxic material contents, which are pollutants. There are many environmental threats owed to the disposal of electronic waste; off-gasses, such as dioxins, furans, polybrominated organic pollutants, and polycyclic aromatic hydrocarbons, can be generated during thermal treatments. which can cause serious health problems if effective off=gas cleaning systems are not developed and improved. Moreover, heavy metals will dissolve, and release into the ground water from the landfill sites. Such waste PCBs contain precious metals which are of monetary value. Therefore, it is beneficial to recover the metal content and protect the environment from pollution. Hydrometallurgy is a successful technique used worldwide for the recovery of precious metals (especially gold and silver) from ores, concentrates, and waste materials. It is generally preferred over other methods because it can offer high recovery rates at a relatively low cost. This article reviews the recent trends and developments with regard to the recycling of precious metals from waste PCBs through hydrometallurgical techniques, such as leaching and recovery.展开更多
Excessive inter-contamination with heavy metals hampers the application of biological treatment products derived from mixed or mechanically-sorted municipal solid waste(MSW). In this study, we investigated fine part...Excessive inter-contamination with heavy metals hampers the application of biological treatment products derived from mixed or mechanically-sorted municipal solid waste(MSW). In this study, we investigated fine particles of 〈 2 mm, which are small fractions in MSW but constitute a significant component of the total heavy metal content, using bulk detection techniques. A total of 17 individual fine particles were evaluated using synchrotron radiation-based micro-X-ray fluorescence and micro-X-ray diffraction. We also discussed the association, speciation and source apportionment of heavy metals. Metals were found to exist in a diffuse distribution with heterogeneous intensities and intense hot-spots of 〈 10 μm within the fine particles. Zn–Cu, Pb–Fe and Fe–Mn–Cr had significant correlations in terms of spatial distribution. The overlapped enrichment, spatial association, and the mineral phases of metals revealed the potential sources of fine particles from size-reduced waste fractions(such as scraps of organic wastes or ceramics) or from the importation of other particles. The diverse sources of heavy metal pollutants within the fine particles suggested that separate collection and treatment of the biodegradable waste fraction(such as food waste) is a preferable means of facilitating the beneficial utilization of the stabilized products.展开更多
Impact of waste fuels(virgin/waste wood, mixed biofuel(peat, bark, wood chips) industrial,household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been...Impact of waste fuels(virgin/waste wood, mixed biofuel(peat, bark, wood chips) industrial,household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr,As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature.Total concentration in ashes decreased in order of Zn 〉 Cu 〉 Pb 〉 Cr 〉 Sb 〉 As 〉 Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers(especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions.Concentration levels in ash and ash matrix properties(association of elements on ash particles)are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in 〉50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.展开更多
The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-m...The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy(FTIR), Solid carbon nuclear magnetic resonance spectroscopy(CNMR)), silicon-29 nuclear magnetic resonance spectroscopy(Si NMR)), and X-ray diffraction spectroscope((XRD) were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb(II) from the aqueous solution. The Pb(II)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy(FTIR)),scanning electron microscopy(SEM)), and X-ray photoelectron spectroscopy((XPS)). From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(II). Kinetic studies indicated that the adsorption of Pb(II)followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb(II) ions was 430 mg/g. Thus, the waste linear low-density polyethylene-g-poly(acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(II) adsorbent.展开更多
文摘Many nanoparticles have been created over the last few decades using a variety of techniques and used to develop environmental technology, including water treatment, the detection of persistent contaminants, and soil and water remediation. The studies of alternative inputs for nanoparticle production as well as the use of green synthesis techniques are driven by the field of materials science and engineering’s growing interest in increasing the sustainability of the processes involved in their production. In this paper, we begin by providing an overview of the fundamental principles of producing nanoparticles from different sources, such as plastic, electronic, metal, and industrial waste. We elaborate on key facts of waste identification as a workable input for the treatment and recovery of metal and carbon-based nanoparticles. We next go over several controlling factors that play a role in creating nanoparticles, pointing out probable conclusions as we go. Then, we show some instances of waste-derived nanoparticles used in a proof-of-concept experiment of technology for applications in water quality and safety. Before scaling up production and implementing waste-derived nanoparticles, there are several present problems from the toxicological and life-cycle perspectives that must be taken into account.
基金Supported by the National Natural Science Foundation of China(51208022)the National Water Pollution Control and Management Technology Major Project(2011ZX07301-004-01)
文摘Stormwater runoff has become an important source of surface water pollution. Bioretention, a low impact development measure in urban stormwater management, has been proven to be effective in the removal of pollutants from stormwater runoff, with appropriate bioretention media. In this study, construction wastes were selected as bioretention media to remove heavy metals from stormwater runoff. Static and dynamic adsorption batch experiments were carried out to investigate the adsorption of heavy metals in simulated stormwater runoff system with construction wastes in different particle sizes. The experimental results show that the pseudo-secondorder kinetic model characterizes the adsorption process and the adsorption equilibrium data are well described by Freundlich isotherm model. The construction wastes used can remove heavy metals from stormwater runoff effectively, with their average removal rates all more than 90%. The particle size of construction wastes greatly influences the equilibrium time, rate and adsorption capacity for heavy metals.
基金Funded by the Key Project of National Natural Science Foundation of China(No.51472040)
文摘The geopolymer samples were prepared with smelting waste slag of non-ferrous metal as the raw material and water glass as the activator. The effect of modulus of water glass and water binder ratio on the compressive strength was studied. The results show that the strength of the geopolymer activated by water glass with modulus of 1.1 and water binder ratio of 0.28 can maintain an increasing trend in the 90 curing days. Through the analyses with XRD, SEM(EDS), and FTIR, the main reaction products are found to be geopolymer gels, which bond the crystalline minerals to provide strength. The molecular chains of amorphous phase in slag become shorter after depolymerization-polycondensation.
文摘Research conducted on ceramic materials has been investigating the incorporation of solid waste into their formulations,driven by the proper disposal of such waste and the reduction of negative environmental impacts.This study analyzed the effects of adding aluminum powder residue to the physical properties of ceramic masses with the aim of obtaining new formulations for ceramic tiles.The aluminum residue and the standard mass for ceramic tile production were chemically characterized and homogenized to obtain new formulations with the incorporation of 4%,6%,8%,and 10%aluminum powder in the ceramic mass.The specimens were uniaxially pressed and sintered at a temperature of 1,200°C for 2 h,undergoing three different temperatures(100°C,400°C,and 650°C)for 30 min each.They were evaluated for WA(water absorption),RLq(linear shrinkage),SEM(scanning electron microscopy),and TRF(flexural strength)modulus.The results demonstrate that the addition of aluminum powder residue is feasible in the proposed formulations(4%,6%,8%,and 10%),as they enhance the mechanical properties of the ceramics compared to the formulation with 0%residue,at a sintering temperature of 1,200°C.
文摘IBC Advanced Technologies' Molecular Recognition Technology(MRT) products,trade named SuperLig,selectively and rapidly bind with target metal ions to remove them from solution.The MRT process can produce a high purity separation product of maximum added value at low cost.In this paper,applications of MRT in the precious metals industry,including selective commercial separations involving Au,Pd,Pt,Rh,and Ru,are described and discussed.Application of MRT to the analytical determination of precious metals is presented.Potential use of MRT in recovering precious metals from end-of-life(EOL) products is discussed.
文摘This study compared the physicochemical parameters and heavy metal levels in soil samples from selected anthropogenic sites within Enugu metropolis, Enugu State, Nigeria using standard analytical methods. Soil samples at depths (0 - 20 cm) and (20 - 40 cm) were collected from waste dump sites, metal scrap dumps, fuel filling stations and auto-mechanic workshops and analyzed for physicochemical characteristics and heavy metal levels. Atomic absorption spectrophotometer was used for heavy metal determination while conventional analytical methods were employed for physicochemical parameters evaluation of the soil samples. At soil depths 0 - 20 cm and 20 - 40 cm the respective mean range of pH, electrical conductivity, organic matter and organic carbon contents in the soil samples were, 6.33 - 6.74, 101.46 - 123.21 <em>μ</em>S/cm, 6.41% - 8.35% and 13.73% - 16.14% for auto-mechanic workshops;6.92 - 7.43, 56.46 - 60.02 <em>μ</em>S/cm, 1.53% - 2.20% and 11.93% - 12.60% for fuel filling stations;7.14 - 7.84, 70.81 - 77.71 <em>μ</em>S/cm, 3.81% - 4.12% and 8.57% - 9.24% for metal scrap dumps;6.54 - 6.81, 94.40 - 100.71 <em>μ</em>S/cm, 8.83% - 10.75% and 18.26% - 20.81% for waste dump sites. The pH of the top soil samples from auto-mechanical workshop was below the WHO recommended limits for agricultural purposes. The physic-chemical characteristics of the soil samples decreased with soil depths indicating therefore that anthropogenic activities greatly influence the soil characteristics at the top soils than the sub-soils. The electrical conductivity values of top and sub-soil samples from the studied auto-mechanical workshops were above the recommended limits. At soil depths 0 - 20 cm and 20 - 40 cm, the respective mean range of Zn, Pb and Cd in the soil samples were 17.29 - 19.16 <em>μ</em>g/g, 0.704 - 0.96 <em>μ</em>g/g and 0.26 - 0.33 <em>μ</em>g/g for auto-mechanic workshops;4.13 - 4.88 <em>μ</em>g/g, 0.21 - 0.32 <em>μ</em>g/g and 0.03 - 0.11 <em>μ</em>g/g for fuel filling stations;30.02 - 36.11 <em>μ</em>g/g, 0.43 - 0.48 <em>μ</em>g/g and 0.15 - 0.19 <em>μ</em>g/g for metal scrap dumps;9.30 - 10.84 <em>μ</em>g/g, 0.53 - 0.60 <em>μ</em>g/g and 0.38 - 0.45 <em>μ</em>g/g for waste dump sites. The mean levels of Pb in soil samples from mechanic workshops and waste dump sites were above the recommended permissible limits for agricultural purposes. The study therefore indicated that these sites (auto-mechanic workshops and waste dump sites) could be major sources of Pb pollution to nearby farmlands, streams and the general environment. Plants grown on or around these sites may not produce high yields and could be severely contaminated with heavy metals which portend health danger to food consumers within the environment.
基金Supported by the Project of Shangai State-owned Assets Supervision and Administration Commission(2013019)Project of Shanghai Science and Technology Commission(13231201901)+1 种基金Innovation Foundation of Shanghai Science and Technology Commission(11231200200)Special Project for Zhangjiang High-tech Park in Shanghai(201505-HP-C104-005)
文摘The fly ash from two municipal solid waste incineration plants in Shanghai was treated by the self-developed organic composite chelating agent. The results indicated that the stabilization effect of Pb in the fly ash by the composite chelating agent was the best,and the proportions of its easily leaching form in the two kinds of fly ash decreased from 29. 60% and 27. 49% to 3. 05% and 0. 29% respectively. The leaching toxicity of stabilized fly ash was lower than the limits of Standard for Pollution Control on the Landfill Site of Municipal Solid Waste( GB 16889- 2008),so it can be landfilled separately in the landfill site of municipal solid waste.
文摘Knowledge about heavy metal release from industrial solid wastes(ISWs) is crucial for better management of their environmental risks. This study was conducted to investigate the effect of organic and inorganic acids, clay minerals, and nanoparticles(NPs) on the release of heavy metals from sugar factory waste, ceramic factory waste, leather factory waste, and stone cutting waste. The influence of the extractants on heavy metal release from these ISWs was in the following descending order: citric acid > oxalic acid > nitric acid≥ sulfuric acid > Ca Cl2. Addition of clay minerals and NPs as adsorbents decreased heavy metal release, which was significantly lower in NP-treated wastes than in the clay mineral-treated wastes. On the other hand, the presence of organic and inorganic acids increased heavy metal adsorption by NPs and clay minerals. These results suggest that NPs can be applied successfully in waste remediation,and organic and inorganic acids play an important role in the removal of heavy metals from the studied adsorbents.
文摘Bottom ash is an inevitable by-product fi'om municipal solid waste (MSW) incineration plants. Recycling it as additives for cement production is a promising disposal method. However, the heavy metals and chlorine are the main limiting factors because of the potential environmental risks and corrosion of cement kilns. Therefore ,investigating heavy metal and chlorine characteristics of bottom ash is the significant prerequisite of its reuse in cement industries. In this study, a correlative analysis was conducted to evaluate the effect of the MSW components and collection mode on the heavy metal and chlorine characteristics in bottom ash. The chemical speciation of insoluble chlorine was also investigated by synchrotron X-ray diffraction analysis. The results showed that industrial waste was the main source of heavy metals, especially Cr and Pb, in bottom ash. The higher contents of plastics and kitchen waste lead to the higher chlorine level (0.6 wt.%-0.7 wt.%) of the bottom ash. The insoluble chlorine in the MSW incineration bottom ash existed primarily as AlOCl, which was produced under the high temperature (1250℃) in incinerators.
基金the support provided by China Scholarship Council, Sheng Yun-Fei College Students Scientific and Technological Innovation Fundthe National Science & Technology Pillar Program (No. 2013BAD21B03)
文摘The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb2+and Zn2+in aqueous single-metal solutions. A p H value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients(above 0.99 for both metal ions) and insignificant lack of fit(p = 0.0838 and 0.0782 for Pb2+and Zn2+, respectively). Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation(between –NH2,-CN and metal ions) and ion-exchange(between –COOH and metal ions). The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions.
基金This research was financially supported, in part, by the National Natural Science Foundation of China (No. 21407105), Shanghai Municipal Natural Science Foundation (No. 14ZR1416700), SPU Graduate project fund (A O1GY17F022 ), SPU Key Disciplines Subject (XXKZD1602 ) and Shanghai Cooperative Centre for WEEE Recycling (ZF1224).
文摘Currently, increasing amounts of end-of-life (EoL) electronic products are being generated due to their reduced life spans and the unavailability of suitable recycling technologies. In particular, waste printed circuit boards (PCBs) have become of global concern with regard to environmental issues because of their high metal and toxic material contents, which are pollutants. There are many environmental threats owed to the disposal of electronic waste; off-gasses, such as dioxins, furans, polybrominated organic pollutants, and polycyclic aromatic hydrocarbons, can be generated during thermal treatments. which can cause serious health problems if effective off=gas cleaning systems are not developed and improved. Moreover, heavy metals will dissolve, and release into the ground water from the landfill sites. Such waste PCBs contain precious metals which are of monetary value. Therefore, it is beneficial to recover the metal content and protect the environment from pollution. Hydrometallurgy is a successful technique used worldwide for the recovery of precious metals (especially gold and silver) from ores, concentrates, and waste materials. It is generally preferred over other methods because it can offer high recovery rates at a relatively low cost. This article reviews the recent trends and developments with regard to the recycling of precious metals from waste PCBs through hydrometallurgical techniques, such as leaching and recovery.
基金supported by the National Basic Research Program of China (No. 2011CB201500)the National Social Science Fund of China (No. 12&ZD236)the National Natural Science Foundation of China (No. 21277096)
文摘Excessive inter-contamination with heavy metals hampers the application of biological treatment products derived from mixed or mechanically-sorted municipal solid waste(MSW). In this study, we investigated fine particles of 〈 2 mm, which are small fractions in MSW but constitute a significant component of the total heavy metal content, using bulk detection techniques. A total of 17 individual fine particles were evaluated using synchrotron radiation-based micro-X-ray fluorescence and micro-X-ray diffraction. We also discussed the association, speciation and source apportionment of heavy metals. Metals were found to exist in a diffuse distribution with heterogeneous intensities and intense hot-spots of 〈 10 μm within the fine particles. Zn–Cu, Pb–Fe and Fe–Mn–Cr had significant correlations in terms of spatial distribution. The overlapped enrichment, spatial association, and the mineral phases of metals revealed the potential sources of fine particles from size-reduced waste fractions(such as scraps of organic wastes or ceramics) or from the importation of other particles. The diverse sources of heavy metal pollutants within the fine particles suggested that separate collection and treatment of the biodegradable waste fraction(such as food waste) is a preferable means of facilitating the beneficial utilization of the stabilized products.
基金Varmeforsk(Thermal Engineering Research Association)(Q4-251)is acknowledged for financial support to Mattias Backstrom.Anjali Bajwa is greatly acknowledged for assistance with grammatical and technical issues
文摘Impact of waste fuels(virgin/waste wood, mixed biofuel(peat, bark, wood chips) industrial,household, mixed waste fuel) and incineration technologies on partitioning and leaching behavior of trace elements has been investigated. Study included 4 grate fired and 9 fluidized boilers. Results showed that mixed waste incineration mostly caused increased transfer of trace elements to fly ash; particularly Pb/Zn. Waste wood incineration showed higher transfer of Cr,As and Zn to fly ash as compared to virgin wood. The possible reasons could be high input of trace element in waste fuel/change in volatilization behavior due to addition of certain waste fractions. The concentration of Cd and Zn increased in fly ash with incineration temperature.Total concentration in ashes decreased in order of Zn 〉 Cu 〉 Pb 〉 Cr 〉 Sb 〉 As 〉 Mo. The concentration levels of trace elements were mostly higher in fluidized boilers fly ashes as compared to grate boilers(especially for biofuel incineration). It might be attributed to high combustion efficiency due to pre-treatment of waste in fluidized boilers. Leaching results indicated that water soluble forms of elements in ashes were low with few exceptions.Concentration levels in ash and ash matrix properties(association of elements on ash particles)are crucial parameters affecting leaching. Leached amounts of Pb, Zn and Cr in 〉50% of fly ashes exceeded regulatory limit for disposal. 87% of chlorine in fly ashes washed out with water at the liquid to solid ratio 10 indicating excessive presence of alkali metal chlorides/alkaline earths.
基金supported by the USM short-term grant (Ac No.: 8044043)by the USM fellowship scheme for PhD study (to M. Irani)Water Program at University of Wyoming
文摘The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy(FTIR), Solid carbon nuclear magnetic resonance spectroscopy(CNMR)), silicon-29 nuclear magnetic resonance spectroscopy(Si NMR)), and X-ray diffraction spectroscope((XRD) were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb(II) from the aqueous solution. The Pb(II)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy(FTIR)),scanning electron microscopy(SEM)), and X-ray photoelectron spectroscopy((XPS)). From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(II). Kinetic studies indicated that the adsorption of Pb(II)followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb(II) ions was 430 mg/g. Thus, the waste linear low-density polyethylene-g-poly(acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(II) adsorbent.