농업환경에서 발생하는 미세플라스틱 필름의 Cd, Pb 흡착 특성

국문 초록 (Abstract)

목적: 플라스틱은 편리성, 단열성으로 일상 및 여러 가지 산업분야에서 다양하게 활용되고 있고, 플라스틱의 사용량은 계속 증가하는 추세이다. 농업환경에서는 비닐하우스, 멀칭비닐 등의 형태로 플라스틱이 사용되고 있다. 사용 후 환경으로 유입된 플라스틱은 물리적, 화학적, 생물학적 작용으로 작은 단위로 분해된다. 이 중 입자 사이즈가 5 mm 이하인 플라스틱을 미세플라스틱이라 정의한다. 토양 중에 잔류하는 미세플라스틱은 표면적이 넓기 때문에 중금속을 포함한 다양한 오염물질을 흡착시켜 농경지 생태계에 영향을 줄 개연성이 있다. 본 연구에서는 농업환경에서 빈번하게 발생하는 미세플라스틱 필름의 납(Pb)과 카드뮴(Cd)의 흡착특성을 평가하고자 한다.
방법: 본 연구에서는 농업환경에서 빈번하게 발생하는 미세플라스틱 필름의 Pb와 Cd 흡착특성을 평가하고자 한다. PVC (polyvinyl chloride) 필름 한 가지와 PE (polyethylene) 필름 두 가지를 5 mm × 5 mm 이하로 잘라 미세플라스틱을 준비한 후, Pb 용액 또는 Cd 용액에 넣어 72시간 동안 흡착 실험을 수행하였다. 흡착실험결과를 Langmuir, Freundlich, Temkin 등온 흡착 모델에 적용하였다.
결과 및 토의 : 등온 흡착 실험 결과를 Langmuir, Freundlich, Temkin 모델을 이용해 도식화한 결과, 전반적으로 Langmuir 및 Freundlich 모델에 잘 맞는 경향(R² > 0.9)을 보였고, Temkin 모델은 상대적으로 잘 맞지 않는 경향을 보였다. 플라스틱 종류와 관계 없이, Pb에 대한 흡착친화도를 나타내는 Langmuir 상수(KL)의 값과 최대흡착에너지를 의미하는 Temkin 상수(AT)의 값이 Cd에 대한 값보다 더 높게 나왔고, 흡착강도와 관련 있는 Freundlich 상수(nF) 는 Pb > Cd > 1의 경향을 나타내었다. 이는 Cd보다 Pb의 PVC와 PE에 대한 흡착친화도가 크다는 것을 의미한다.
결론: 본 연구는 토양 중 잔류하는 미세플라스틱 필름이 Cd와 Pb 같은 중금속을 흡착하고, 따라서 토양환경 중 중금속의 거동에 유의한 영향을 미칠 수 있음을 시사한다. 또한 폐플라스틱의 환경 문제가 사회적 이슈로 대두되고 있는 요즘, 다양한 폐플라스틱으로부터 발생할 수 있는 미세플라스틱의 지중환경 중 관리의 필요성에 대한 합리적 근거를 제공하고, 따라서 토양 환경 내 미세플라스틱에 대한 추가 연구가 이루어질 필요가 있다.

다국어 초록 (Multilingual Abstract)

Objectives : Plastics are widely used in daily life and in various industrial fields due to their convenience and thermal insulation, and the use of plastics is continuing to increase. In agricultural environments, plastics are largely used for vinyl houses and mulching vinyl. Used plastics are degraded into small fragments through physical, chemical, and biological processes. Among these, plastics with a particle size of 5 mm or less are defined as microplastics. Since microplastics have a relatively large surface area, various pollutants including heavy metals can potentially be adsorbed and affect the agricultural ecosystem. The purpose of this study is to evaluate the Pb and Cd adsorption characteristics on microplastic films frequently generated in agricultural environments.
Methods : The Pb and Cd adsorption characteristics on microplastic films were studied with 3 different plastic films. Microplastic samples were prepared by cutting PVC (polyvinyl chloride) and PE (polyethylene) films to have the sizes of < 5 mm × 5 mm. The prepared microplastic samples were placed in Pb or Cd solutions having a range of concentrations and shaken for 72 h for sorption tests. The experimental results were fitted to the Langmuir, Freundlich, and Temkin isothermal adsorption models.
Results and Discussion : The isothermal adsorption test results obtained fitted well to the Langmuir and Freundlich models (R² > 0.9), but not the Temkin model. Regardless of the plastic type, the values of Langmuir constant (KL) and Temkin constant (AT) for Pb were larger than those for Cd, and the Freundlich constant (nF) showed a tendency of Pb > Cd > 1, indicating the greater Pb sorption strength or affinity than Cd on PVC and PE.
Conclusions : This study shows that the microplastics in soil adsorb heavy metals like Cd and Pb affecting the heavy metal fate in the soil environment. With an increasing attention on the environmental problems due to plastic wastes, this study provides the basis for the need of management of soil environment. Therefore, further research on microplastics in soil environment is required.

목차 (Table of Contents)

• 1. 서론
• 2. 실험방법
• 3. 결과 및 고찰
• 4. 결론
• References

참고문헌 (Reference)

1 A. A. Souza Machado, 53 (53): 6044-6052, 2019

2 김연태, "지중환경에서 미세플라스틱의 이동성에 대한 고찰" 한국지하수토양환경학회 24 (24): 1-12, 2019

3 엄주현, "수중에서 미세플라스틱인 Polypropylene의 Cd 흡착특성 평가" 한국환경농학회 38 (38): 83-88, 2019

4 M. R. Jung, "Validation of ATR FT-IR to identify polymers of plastic marine debris, including those ingested by marine organisms" 127 : 704-716, 2018

5 P. Farrell, "Trophic level transfer of microplastic:Mytilus edulis (L.) to Carcinus maenas (L.)" 177 : 1-3, 2013

6 A. E. Nemr, "Treatment of wastewater containing toxic chromium using new activated carbon developed from date palm seed" 152 (152): 263-275, 2008

7 W. Yuan, "Toxicological effects of microplastics and heavy metals on the Daphnia magna" 746 : 141254-, 2020

8 V. Godoy, "The potential of microplastics as carriers of metals" 255 : 113363-, 2019

9 L. Ding, "The occurrence and distribution characteristics of microplastics in the agricultural soils of Shaanxi Province, in north-western China" 720 : 137525-, 2020

10 M. E. Labib, "The effect of processing additives on the surface properties of polyvinyl chloride" 262 : 551-556, 1984

11 Q. Wang, "The adsorption behavior of metals in aqueous solution by microplastics effected by UV radiation" 87 : 272-280, 2020

12 G. Sposito, "The Chemistry of Soils" Oxford University Press, Inc 203-206, 2008

13 P. Beneš, "Surface charge and adsorption properties of polyethylene in aqueous solutions of inorganic electrolytes" 251 : 766-771, 1973

14 F. Gao, "Study on the capability and characteristics of heavy metals enriched on microplastics in marine environment" 144 : 61-67, 2019

15 X. Guo, "Sorption properties of cadmium on microplastics: the common practice experiment and a two-dimensional correlation spectroscopic study" 190 : 110118-, 2020

16 G. A. Meligi, "Removal of some heavy metal ions using grafted polyurethane foam" 47 (47): 106-113, 2007

17 R. Geyer, "Production, use, and fate of all plastics ever made" 3 : e1700782-, 2017

18 Korean Statistics Information Service, "Production of agricultural waste vinyl 2004-2018"

19 M. E. Hodson, "Prendergast-Miller, K. L. Thorpe, Plastic bag derived-microplastics as a vector for metal exposure in terrestrial invertebrates" 51 (51): 4714-4721, 2017

20 S.-K. Kim, "Monitoring results for occurrence of microplastics in agricultural" 214-, 2019

21 D. Brennecke, "Microplastics as vector for heavy metal contamination from the marine environment" 178 : 189-195, 2016

22 D. Brennecke, "Microplastics as vector for heavy metal contamination from the marine environment" 178 : 189-195, 2016

23 A. A. Souza Machado, "Microplastics as an emerging threat to terrestrial ecosystems" 24 : 1405-1416, 2018

24 N. F. Zon, "Kinetics and isotherm of cadmium adsorption onto polyethylene microbeads in artificial seawater" 476 (476): 012130-, 2020

25 L. A. Holmes, "Interactions between trace metals and plastic production pellets under estuarine conditions" 167 : 25-32, 2014

26 M. A. Al-Ghouti, "Guidelines for the use and interpretation of adsorption isotherm models: a review" 393 : 122383-, 2020

27 A. T. Tran, "From waste disposal to valuable material: sulfonating polystyrene waste for heavy metal removal" 8 (8): 104302-, 2020

28 M. Lang, "Fenton aging significantly affects the heavy metal adsorption capacity of polystyrene microplastics" 722 : 137762-, 2020

29 K. Li, "Estimation of electronegativity values of elements in different valence states" 110 : 11332-11337, 2006

30 D. Sparks, "Environmental Soil Chemistry" Academic Press Inc 104-127, 2003

31 X. Li, "Enhancement in adsorption potential of microplastics in sewage sludge for metal pollutants after the wastewater treatment process" 157 : 228-237, 2019

32 X. Huang, "Competitive heavy metal adsorption onto new and aged polyethylene under various drinking water conditions" 385 : 121585-, 2020

33 R. Mao, "Aging mechanism of microplastics with UV irradiation and its effects on the adsorption of heavy metals" 122515-, 2020

34 J. Zou, "Adsorption of three bivalent metals by four chemical distinct microplastics" 248 : 126064-, 2020

35 Y. Niu, "Adsorption of heavymetal ions from aqueous solution onto chitosan-modified polyethylene terephthalate (PET)" 43 (43): 4213-4225, 2017