• Current Photovoltaic Research
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• v.3 no.4
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• pp.126-129
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• 2015

Over the last two decades, quantum dot (QD) solar cells have attracted much attention due to the unique properties of QDs, including band gap tunability, slow hot electron cooling, and multiple exiton generation effect. However, most of the QDs employed in photovoltaic devices contain toxic heavy-metals such as cadmium or lead, which may limit the commercial application. Therefore, recently, heavy-metal-free QDs such as Cu-In-S or Cu-In-Se have been developed for application in solar cells. Here, we review the research trends in heavy-metal-free QD solar cells, mainly focusing on Cu-In-Se QD-sensitized solar cells (QDSC).

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.224-227
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• 2001

In general, municipal solid waste incinerator fly ash (MSWIF) has a potential hazardous leaching of heavy metal with subsurface environment variation. Therefore, to remove the heavy metal from MSWIF electrokinetic technology were used. With constant current density condition heavy metals in MSWIF removed by ion migration. During 7 days operation 40~80% of Cr, Cd and As were removed and longer operation, 14 days treatment, showed 35~100% removal efficiency.

• Journal of environmental and Sanitary engineering
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• v.14 no.1
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• pp.80-87
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• 1999

According to the fact that algae, which is usually used as a biosorbent, contains chlorophyll, we used the chlorophyll as an adsorbent. In this study, chlorophyll is immobilized by agar, which was made of platan, oak, ginkgo and pine. We investigated the removing capacity of biosorbents to toxic heavy metals (Pb, CU, Cd, Zn) in the single ion solution. Then the experimental parameters were pH, reaction time and concentration of heavy metal ions.The optimum conditions for the adsorption of heavy metals were as follows : pH range was 4~5, reaction time was 40mon, and the highest ratio of the removing rate was 50~70 ppm. The order of the amount of Pb, Cu and Cd removed was specified as oak > ginkgo > pine > platan in these conditions and as pine > ginkgo > oak > platan at Zn. Fro the results of the desorption experiments, we found that the heavy metal with the highest ratio of desorption in the single ion adsorbent was Cu.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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• pp.413-420
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• 2008

In order to utilize cinder melting slag as a filter media to control the quality of early rainwater, its environmental stability was verified by heavy metal elution experiment and improved by pre-treatment. Possibilities of improving its function as an absorbent was considered. Absorption characteristics of melting slag before and after the pre-treatment were analyzed by heavy metal equilibrium and stationary-phase column experiments, which in turn were analyzed by comparison experiment with activated carbon. As a result of heavy metal elution experiment, every metal item existed in a much lower amount than the criteria or was not detected, implying that there is no problem recycling it. Absorption equilibrium experiment showed that the time for pre-treatment melting slag to reach the equilibrium was reduced, while the absorbed amount was greatly increased. Stationary-phase column experiment assures us that the elimination rate was not changed much by influx rate, pH and the change in packing volume rate, indicating that this melting slag can be used not only as a filter media to control the quality of early rainwater but also in many areas of water-processing.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.277-284
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• 2012

This study developed a new ceramics in which natural zeolite was mixed and calcined with industrial by-product such as converter slag, red mud, and fly ash and evaluated the feasibility of the ceramics for removal of heavy metals in acid wastewater. The removal rate of heavy metal by ceramics increased in the order of ZS (zeolite and slag) > ZR (zeolite and red mud) > ZF (zeolite and fly ash) ceramics. The alkalinity increment and coherence of ceramics were increased in the order of ZS > ZR > ZF ceramics. The mixing ratio of natural zeolite to industrial by-product for maximum removal efficiency of heavy metal was 1:1 for ZS ceramics and 1:3 for ZR and ZF ceramics. The order of removal efficiency of heavy metal was observed to be ZS > ZR > ZF ceramics under the mixing ratio of 1:1 for ZS ceramics and 1:3 for ZR and ZF ceramics. The removal efficiency of heavy metal by ZS ceramics with 1:1 mixing ratio was Al 100%, Cd 54.6%, Cr 99.9%, Cu 98.7%, Fe 99.9%, Mn 42.2%, Ni 59.9%, Pb 99.8%, Zn 87.6%, respectively. In addition, the removal capacity of heavy metal by ZS ceramics was observed to be Al 2.01 mM/g, Cd 0.27 mM/g, Cr 1.02 mM/g, Cu 0.83 mM/g, Fe 0.95 mM/g, Mn 0.41 mM/g, Ni 0.55 mM/g, Pb 0.25 mM/g, Zn 0.70 mM/g, respectively. The comparative evaluation in the light of removal capacity, alkalinity increment, and coherence of ceramics showed the ZS ceramics had higher feasibility as a media than others for removal of heavy metals in acid wastewater.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.494-499
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• 2001

The present work investigates the possible use of fly ash for the removal of heavy metal ions from aqueous solutions. Batch experiments were conducted and the influences of metal concentration, pH, and fly ash concentration were investigated. Heavy metals used in these studies were zinc, lead and cadmium. Adsorption studies were done over a range of pH values (3-10) at $25^{\circ}C$ and heavy metal concentrations of 10-400 mg/L using fly ash concentrations of 10, 20 and 40 g/L. Experiments were also conducted without fly ash to determine the extent of heavy metal removal by precipitation. Kinetic and equilibrium experiments were performed and adsorption data were correlated with both Langmuir and Freundlich adsorption models. The results indicate that fly ash can be used as an adsorbent for heavy metals in the aqueous solutions, yet the degree of removal depends on the pH.

• Journal of Pharmacopuncture
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• v.10 no.1 s.22
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• pp.67-77
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• 2007

Objectives : Heavy metal contents in cultivated wild ginseng from Korea and China were evaluated for the safety purpose. Methods : Arsenic(As), cadmium(Cd), lead(Pb), mercury(Hg), copper(Cu), chromium(Cr), and selenium(Se) from the root, stem, and leaves of the Korean cultivated wild ginseng and the root of the Chinese cultivated wild ginseng were analyzed for the existence of heavy metal contents. Results : Most of heavy metals weren't detected in all the samples. Copper and lead were found in very minute volume and didn't reach the toxic concentration level of 10mg/kg. Samples used in the test were grown in non-contaminated areas, free from heavy metal contamination. Conclusions : Based on above results, cultivated wild ginseng from Korea and China are relatively safe from the heavy metal exposure. But for more rigorous quality control, an epidemiological survey using the samples from more diverse areas should be conducted.

• Journal of Environmental Impact Assessment
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• v.29 no.4
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• pp.252-271
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• 2020

In this study, we investigated physical and chemical properties such as grain size, heavy metal pollution, magnetic properties, and their environmental impacts of road dusts (RD) collected from 14 sampling points in Daebul industrial Complex. Heavy metal concentrations in RD were in the order of Fe>Zn>Cu>Pb>Cr>Ni>As>Cd>Hg, and this pollution pattern was related to major industries and traffic activities in this area. The results of the correlation analysis between heavy metal elements and particle size in RD showed that Fe and all of analyzed heavy metals had a significant correlation with each other and metal concentrations had a significantly negative correlation (p<0.05). However, due to the input of large metal particles some heavy metal concentrations in the particle fraction of >1000 ㎛ were highest. Pollution load per unit area of this fraction was the highest among the grain size fractions. Cr, Ni, Cu, Zn, Cd, Pb levels in RD decreased and the levels of Cr, Ni, Cu, Zn, Cd, and Pb were reduced to 85 (As) -22 (Ni)% of the whole after removal of MFs fraction from RD. The mean heavy metal levels in the study area did not exceed the soil contamination guide value of Korea, indicating that heavy metal levels in RD were not a concern. However, at some sampling points, Zn concentrations were exceeded the soil contamination guide value for the 3rd areas of Korea and this result indicated that further studies of the impact of RD on the surrounding environment through re-suspension or non-point pollution, and of effective management methods are required.

• Analytical Science and Technology
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• v.13 no.3
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• pp.394-398
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• 2000

The mineralogical properties of natural zeolite comixed with montmorillonite were investigated by the chemical composition analysis, X-ray diffraction analysis, and differential scanning calorimetry. The experimental results on the removal of heavy metal ions by using the natural sample are summerized as follows. The removal of the heavy metal in solution is greatly influenced by the pH. Also, the removal capacity of heavy metal ions by zeolite and montmorillonite have increased in order of $Cu^{2+}>Cd^{2+}>Ni^{2+}$.

• Journal of Environmental Health Sciences
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• v.45 no.6
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• pp.561-568
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• 2019

Objectives: The most commonly detected heavy metals in rocks and soils, including Pb, Cd, Cu, Fe, Mn and As, are representative pollutants discharged from abandoned mines and have been listed as potential sources of contamination in drinking water. This study focused on increasing the removal efficiency of heavy metals from drinking water resources by surface modification of natural adsorbents to reduce potential health risks. Methods: Iron oxide coating and graft polymerization with zeolites and talc was conducted for bipolar surface modification to increase the combining capacity of heavy metals for their removal from water. The removal efficiency of heavy metals was measured before and after the surface modification. Results: The removal efficiency of Pb, Cu, and Cd by surface modified zeolite showed 100, 92, and 61.5%, respectively, increases compared to 64, 64, and 38% for non-modified zeolite. This implies that bipolar surface modified natural adsorbents have a good potential use in heavy metal removal. The more interesting finding is the removal increase for As, which has both cation and anion characteristics showing 27% removal efficiency where as non-modified zeolite showed only 2% removal. Conclusions: Zeolite is one of the most widely used adsorptive materials in water treatment processes and bipolar surface modification of zeolite increases its applicability in the removal of heavy metals, especially As.