1
|
Separation of plastic wastes using froth flotation - An overview. Adv Colloid Interface Sci 2022; 308:102769. [PMID: 36116142 DOI: 10.1016/j.cis.2022.102769] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 08/29/2022] [Accepted: 08/30/2022] [Indexed: 11/22/2022]
Abstract
Despite various initiatives and efforts, plastic solid waste (PSW) has become a major global problem due to decades of relentless use of plastics. Since non-biodegradable plastics can persist in the environment for hundreds of years, threatening animal and human life, discarding them into the environment is not a viable option. Plastic recycling is a critical research area that requires urgent attention since less than 10% of the seven billion tons of globally generated plastic waste has been recycled so far. With recent technological developments, it is now possible to recycle many types of PSW using a variety of methods. This review provides an overview of the froth flotation technology that is currently being researched for PSW recycling. Fundamental working principles, the current state of the development, and limitations of this technique are reviewed. It is suggested that froth flotation with continuous development has tremendous potential to result in a more efficient and environmentally friendly approach to PSW recycling.
Collapse
|
2
|
Automatic and continuous separation of mixed waste plastics via magneto-Archimedes levitation. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
3
|
Thanh Truc NT, Le HA, Lee BK. Sono-oxidation treatment of hazardous ABS/PC surface for its selective separation from ESR styrene plastics. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:24771-24784. [PMID: 33244696 DOI: 10.1007/s11356-020-11796-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 11/23/2020] [Indexed: 06/11/2023]
Abstract
This study reports the selective hydrophilization of the ABS/PC blend surface using the peroxide-sonochemical system and then its selective separation by froth flotation technique from other ABS-based plastics (ABS, ABS/PMMA) and PS/HIPS in electronic shredder residue (ESR). FT-IR and XPS measurements confirm that the hydrophilic moiety development on the ABS/PC surface led to increasing the wettability of ABS/PC and then decreased its floatability. The confocal scanning results also support the enhancement of microscale roughness of the treated ABS/PC surface. The enhanced surface roughness is attributed to the oxidative process which degrades hydrophobic moieties and promotes hydrophilic functional groups on the ABS/PC surface using commercial oxidant peroxide and ultrasound. This study also investigated removal of Br-containing compounds on the ABS/PC surface. The optimum conditions for selectively ABS/PC separation are peroxide concentration 2%, power cycle 70%, treatment time 5 min, temperature 50 °C, floating agent concentration 0.4 mg/L, flotation time 2 min, and airflow rate 0.5 L/min. ABS/PC was selectively separated from ESR styrene plastics with high recovery and purity of 98.9% and 99.8%, respectively. Hence, the developed novel surface treatments having removal of hazardous Br chemicals and none-formation of secondary pollutants should be applied for upgrading plastic recycling quality.
Collapse
Affiliation(s)
- Nguyen Thi Thanh Truc
- Institute for the Environmental Science, Engineering and Management, Industrial University of Ho Chi Minh City, No.12, Nguyen Van Bao Street, Ward 4, Go Vap District, Ho Chi Minh City, 70000, Vietnam
| | - Hung Anh Le
- Institute for the Environmental Science, Engineering and Management, Industrial University of Ho Chi Minh City, No.12, Nguyen Van Bao Street, Ward 4, Go Vap District, Ho Chi Minh City, 70000, Vietnam
| | - Byeong-Kyu Lee
- Department of Civil and Environmental Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan, 44610, Republic of Korea.
| |
Collapse
|
4
|
Lee H, Lee H. Separation of auto shredder residue materials using an air table to achieve highly efficient recycling rate. SEP SCI TECHNOL 2020. [DOI: 10.1080/01496395.2020.1824239] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Hansol Lee
- Resources Recycling, University of Science and Technology, Daejeon, Republic of Korea
| | - Hoon Lee
- Mineral Resources Research Division, Korea Institute of Geoscience and Mineral Resources, Daejeon, Republic of Korea
| |
Collapse
|
5
|
Jiang H, Zhang Y, Wang H. Surface Reactions in Selective Modification: The Prerequisite for Plastic Flotation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:9742-9756. [PMID: 32659077 DOI: 10.1021/acs.est.9b07861] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Improper disposal of waste plastic has caused much environmental pollution, but plastic recycling can reduce the amount of new and residual waste plastic in the environment through source control. Plastic flotation can separate waste plastics with similar physical and chemical properties, which suggests its promising application in plastic recycling. With the help of the different hydrophilicities waste plastic can be separated by flotation, and hydrophilization can be accomplished by surface modifications. However, no systematic studies addressing these surface reactions have been published yet, and such modifications are a prerequisite for plastic flotation. In this critical review, we not only summarize the various modification mechanisms, including physical regulation, surface oxidation, surface degradation, dechlorination, and coating, but also have reasonably added additional information for some reactions covering surface reconstruction, plastic degradation, polymer stability, wastewater treatment, soil remediation, and chemical recycling of plastic. An entirely novel concept, the "plastic gene", is also proposed to elaborate on some contradictory results. Plastic flotation with clear surface reactions may promote plastic recycling and thereby control waste plastic at the source, save energy, and reduce microplastics. We also predict challenges for clean, efficient, and practical surface modifications and plastic flotation.
Collapse
Affiliation(s)
- Hongru Jiang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan P.R. China
| | - Yingshuang Zhang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan P.R. China
| | - Hui Wang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan P.R. China
| |
Collapse
|
6
|
Zhang Y, Jiang H, Wang H, Wang C. Separation of hazardous polyvinyl chloride from waste plastics by flotation assisted with surface modification of ammonium persulfate: Process and mechanism. JOURNAL OF HAZARDOUS MATERIALS 2020; 389:121918. [PMID: 31879107 DOI: 10.1016/j.jhazmat.2019.121918] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 12/14/2019] [Accepted: 12/16/2019] [Indexed: 06/10/2023]
Abstract
Plastic separation becomes an effective method to improve the plastic recycling by concentrating a single component from complex plastic mixtures. Based on advanced oxidation process, surface modification assisted by ammonium persulfate ((NH4)2S2O8) was applied to selectively wet plastic surface, achieving the separation of hazardous polyvinyl chloride (PVC) from acrylonitrile butadiene styrene (ABS), polystyrene (PS), and polycarbonate (PC) in forth flotation. The mechanisms were investigated through contact angle, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), as well as scanning electron microscope (SEM). The floatability of PS, PC, and ABS reduces owing to the introduction of carbonyl (O = CO), hydroxyl (-OH), and amide (O = C-NH2) on plastic surfaces, which is the result of the oxidation by sulfate radical (SO4∙-) and the hydrolysis of nitrile group (CN) and butadiene (CC). Then, available reaction equations of ABS, PS, and PC were established to supplement the mechanisms of surface modification. The optimal conditions for flotation separation of PVC are (NH4)2S2O8 concentration 0.2 M, temperature 70 °C, pretreatment time 30 min, pH 10, flotation time 4 min, terpineol dosage 20 mg/L, and particle size 3-4 mm. The recovery and purity of PVC reach 100 % and 99.7 ± 0.2 % respectively, favoring the reuse of separated waste plastic.
Collapse
Affiliation(s)
- Yingshuang Zhang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China
| | - Hongru Jiang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China
| | - Hui Wang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China.
| | - Chongqing Wang
- School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou, 450001, China.
| |
Collapse
|
7
|
Wang J, Wang H, Yue D. Optimizing green ferrate (VI) modification towards flotation separation of waste polyvinylchloride and acrylonitrile-butadiene-styrene mixtures. WASTE MANAGEMENT (NEW YORK, N.Y.) 2020; 101:83-93. [PMID: 31604161 DOI: 10.1016/j.wasman.2019.09.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Revised: 09/06/2019] [Accepted: 09/28/2019] [Indexed: 06/10/2023]
Abstract
The recycling of waste plastics is of considerable significance with environmental and economic benefits, while available separation approaches have been considered as a major bottleneck for its widespread application. Thus, we proposed a simple method, flotation along with surface modification, to separate waste acrylonitrile-butadienestyrene and polyvinylchloride mixtures. Single-factor experiment was conducted to determine the critical parameters in surface modification. Surface response methodology using Box-Behnken Design was performed to optimize separation performance. The quadratic models were generated to predict the floatability of acrylonitrile-butadienestyrene and the difference between the floatability of polyvinylchloride and acrylonitrile-butadienestyrene. The model was also utilized to determine optimized conditions by desirability approaches. The optimized conditions were: concentration = 0.18 M, temperature = 75.00 °C, treatment time = 11.50 min along with stirring rate = 200 rpm. The efficient separation of acrylonitrile-butadienestyrene and polyvinylchloride was achieved, yielding recovery of 98.40% and purity of 98.43%. The experimental responses well agreed with predicted values, demonstrating the accuracy of the prediction model. The formed hydrophilic groups, coated iron oxide, and signs of corrosion were confirmed as the major mechanism for the selective surface hydrophilization of acrylonitrile-butadienestyrene. Consequently, this method is feasible for separation of waste acrylonitrile-butadienestyrene and polyvinylchloride mixtures, and can be expected to promote the sustainable recycling of waste plastics.
Collapse
Affiliation(s)
- Jianchao Wang
- School of Environment, Tsinghua University, Beijing 100084 China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan, China.
| | - Dongbei Yue
- School of Environment, Tsinghua University, Beijing 100084 China.
| |
Collapse
|
8
|
Wang H, Zhang Y, Wang C. Surface modification and selective flotation of waste plastics for effective recycling——a review. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2019.05.052] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
9
|
Zhang Y, Chen S, Wang H, Luo M. Separation of polyvinylchloride and acrylonitrile-butadiene-styrene combining advanced oxidation by S 2O 82-/Fe 2+ system and flotation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2019; 91:80-88. [PMID: 31203945 DOI: 10.1016/j.wasman.2019.04.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/21/2019] [Accepted: 04/22/2019] [Indexed: 06/09/2023]
Abstract
A combining technology of advanced oxidation by S2O82-/Fe2+ system and flotation was proposed for separating polyvinyl chloride (PVC) and acrylonitrile butadiene styrene (ABS). In this research, sodium persulfate was activated by heating and ferrous ions. The separation efficiency of PVC/ABS oxidized by S2O82-/Fe2+ was higher than that by sodium persulfate. The mechanism of this process was investigated through contact angle, Fourier transform infrared spectroscopy (FT-IR) inductively coupled plasma (ICP), nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). The floatability of ABS reduced owing to the introduction of oxygen-containing functional groups such as carbonyl (OCO) and hydroxyl (OH), which was a result of oxidation by sulfate radicals (SO4·-). The optimal conditions for separating PVC and ABS were: Na2S2O8 concentration 0.1 M, molar ratio (S2O82-/Fe2+) 200, treatment time 10 min, flotation time 4 min, frother concentration 14.7 mg L-1 and airflow rate 6.8 mL min-1. Novel kinetics of pretreatment time and flotation were proposed and researched in this work. The max rate constant of PVC/ABS flotation was 0.64 min-1. In addition, the pretreatment solution can be reused for three times with superior performance. The recovery and purity of PVC reached 100% and 99.7%, respectively. According to reasonable evaluation, the combination of S2O82-/Fe2+ advanced oxidation and flotation is a practical and efficient technology for separating PVC and ABS.
Collapse
Affiliation(s)
- Yingshuang Zhang
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China
| | - Shuaijun Chen
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
| | - Maozhi Luo
- School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China
| |
Collapse
|
10
|
Guo C, Zou Q, Wang J, Wang H, Chen S, Zhong Y. Application of surface modification using sodium hypochlorite for helping flotation separation of acrylonitrile-butadiene-styrene and polystyrene plastics of WEEE. WASTE MANAGEMENT (NEW YORK, N.Y.) 2018; 82:167-176. [PMID: 30509579 DOI: 10.1016/j.wasman.2018.10.031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/16/2018] [Accepted: 10/20/2018] [Indexed: 06/09/2023]
Abstract
Acrylonitrile-butadiene-styrene (ABS) and polystyrene (PS), as important fractions of Waste from Electric and Electronic Equipment (WEEE) plastics, show great significances to the recycling of WEEE. The objective of this study is to develop a simple, practical and efficient surface modification method using sodium hypochlorite (NaClO) for separation of waste ABS and PS plastics by the aid of froth flotation. After surface modification, more hydrophilic groups are introduced on ABS surface than that of PS, enhancing its surface hydrophilicity clearly and reducing its recovery in floated products. Single parameter experiments demonstrate NaClO concentration, treatment temperature, treatment time are key parameters in surface modification. Optimization of conditions for surface modification of ABS was conducted by Response Surface Methodology with a Box-Behnken design, and a predicting model was obtained also. The optimum conditions are NaClO concentration of 0.05 M/L, temperature of 67.50 °C, treatment time 59.50 min and stirring rate of 200 rpm. Under optimum conditions, ABS and PS with different particle sizes can be separated efficiently with recovery of 99.18% and 99.47%, and purity of 99.45% and 99.18% respectively. The application of surface modification using sodium hypochlorite can facilitate efficient flotation separation of waste ABS and PS plastics for the recycling of WEEE.
Collapse
Affiliation(s)
- Chenchao Guo
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Qiangpin Zou
- Zhejiang University, Yuquan Campus, Hangzhou, 310007 Zhejiang, China
| | - Jianchao Wang
- School of Environment, Tsinghua University, Beijing 100084, PR China; Key Laboratory of Solid Waste Management and Environment Safety (Tsinghua University), Ministry of Education, Tsinghua University, Beijing 100084, PR China.
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
| | - Shuaijun Chen
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Yiwei Zhong
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| |
Collapse
|
11
|
Wang J, Liu W, Wang H, Wang C, Huang W. Separation of acrylonitrile-butadiene-styrene and polystyrene waste plastics after surface modification using potassium ferrate by froth flotation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2018; 78:829-840. [PMID: 32559978 DOI: 10.1016/j.wasman.2018.07.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 04/26/2018] [Accepted: 07/01/2018] [Indexed: 06/11/2023]
Abstract
This work develops a simple and practical process for separation of acrylonitrile-butadienestyrene (ABS) and polystyrene (PS) waste plastics by froth flotation after surface modification using potassium ferrate. ABS plastics containing brominated flame retardants (BFRs) can release hazardous emissions during the process of disposal. Moreover, ABS and PS are typical styrene plastics with similar properties, posing severe restrictions on their separation for recycling. Thus, potassium ferrate modification was investigated and found to decrease selectively the floatability of ABS, providing available process for separation of ABS and PS. Contact angle measurements, FT-IR, XPS and SEM characterization analysis confirmed that potassium ferrate modification can induce the desired changes in the surface properties of ABS. With consideration to separation of ABS and PS, the optimum conditions are potassium ferrate concentration 0.15 M/L, modification time 15 min, temperature 60 °C, stirring rate 200 rpm, frother concentration 14.50 mg/L and flotation time 2 min. Under optimum conditions, separation of ABS and PS with different mixing ratios was accomplished with a recovery and purity of 98.60% and 98.62% respectively. Moreover, reusing of potassium ferrate solution is feasible, further eliminating emissions and cost of this process. Consequently, surface modification using potassium ferrate can be applied for facilitating flotation separation of ABS and PS waste plastics.
Collapse
Affiliation(s)
- Jianchao Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Weiqi Liu
- School of Public Administration, Central South University, Changsha, 410083 Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
| | - Chongqing Wang
- School of Chemical Engineering and Energy, Zhengzhou University, Zhengzhou, 450001 Henan, China.
| | - Wenqiu Huang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| |
Collapse
|
12
|
Zhao P, Xie J, Gu F, Sharmin N, Hall P, Fu J. Separation of mixed waste plastics via magnetic levitation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2018; 76:46-54. [PMID: 29506775 DOI: 10.1016/j.wasman.2018.02.051] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/11/2018] [Accepted: 02/24/2018] [Indexed: 05/15/2023]
Abstract
Separation becomes a bottleneck of dealing with the enormous stream of waste plastics, as most of the extant methods can only handle binary mixtures. In this paper, a novel method that based on magnetic levitation was proposed for separating multiple mixed plastics. Six types of plastics, i.e., polypropylene (PP), acrylonitrile butadiene styrene (ABS), polyamide 6 (PA6), polycarbonate (PC), polyethylene terephthalate (PET), and polytetrafluoroethylene (PTFE), were used to simulate the mixed waste plastics. The samples were mixed and immersed into paramagnetic medium that placed into a magnetic levitation configuration with two identical NdFeB magnets with like-poles facing each other, and Fourier transform infrared (FTIR) spectroscopy was employed to verify the separation outputs. Unlike any conventional separation methods such as froth flotation and hydrocyclone, this method is not limited by particle sizes, as mixtures of different size fractions reached their respective equilibrium positions in the initial tests. The two-stage separation tests demonstrated that the plastics can be completely separated with purities reached 100%. The method has the potential to be industrialised into an economically-viable and environmentally-friendly mass production procedure, since quantitative correlations are determined, and the paramagnetic medium can be reused indefinitely.
Collapse
Affiliation(s)
- Peng Zhao
- State Key Lab of Fluid Power Transmission and Control, School of Mechanical Engineering, Zhejiang University, Hangzhou, China; Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Jun Xie
- State Key Lab of Fluid Power Transmission and Control, School of Mechanical Engineering, Zhejiang University, Hangzhou, China; Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| | - Fu Gu
- State Key Lab of Fluid Power Transmission and Control, School of Mechanical Engineering, Zhejiang University, Hangzhou, China; Department of Industrial Engineering, Zhejiang University, Hangzhou, China.
| | - Nusrat Sharmin
- Department of Chemical and Environmental Engineering, University of Nottingham, Ningbo, China
| | - Philip Hall
- Department of Chemical and Environmental Engineering, University of Nottingham, Ningbo, China
| | - Jianzhong Fu
- State Key Lab of Fluid Power Transmission and Control, School of Mechanical Engineering, Zhejiang University, Hangzhou, China; Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province, School of Mechanical Engineering, Zhejiang University, Hangzhou, China
| |
Collapse
|
13
|
Flores-Campos R, Estrada-Ruiz RH, Velarde-Sánchez EJ. Study of the physicochemical effects on the separation of the non-metallic fraction from printed circuit boards by inverse flotation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 69:400-406. [PMID: 28888804 DOI: 10.1016/j.wasman.2017.08.049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 06/07/2023]
Abstract
Recycling printed circuit boards using green technology is increasingly important due to the metals these contain and the environmental care that must be taken when separating the different materials. Inverse flotation is a process that can be considered a Green Technology, which separates metallic from non-metallic fractions. The degree of separation depends on how much material is adhered to air bubbles. The contact angle measurement allows to determine, in an easy way, whether the flotation process will occur or not and thus establish a material as hydrophobic or not. With the material directly obtained from the milling process, it was found that the contact angle of the non-metallic fraction-liquid-air system increases as temperature increases. In the same way, the increments in concentration of frother in the liquid increase the contact angle of the non-metallic fraction-liquid-air system. 10ppm of Methyl Isobutyl Carbinol provides the highest contact angle as well as the highest material charging in the bubble.
Collapse
Affiliation(s)
- R Flores-Campos
- Termoplásticos REMI S.A. de C.V., Guillermo Prieto No. 1115-A, Col. Centro, Saltillo, C.P. 25000 Coahuila, Mexico.
| | - R H Estrada-Ruiz
- Tecnológico Nacional de México, Instituto Tecnológico de Saltillo (ITS), Departamento de Mecánica - Mecatrónica, Venustiano Carranza No. 2400, Col. Tecnológico, Saltillo, C.P. 25280 Coahuila, Mexico.
| | - E J Velarde-Sánchez
- Tecnológico Nacional de México, Instituto Tecnológico de Saltillo (ITS), Departamento de Mecánica - Mecatrónica, Venustiano Carranza No. 2400, Col. Tecnológico, Saltillo, C.P. 25280 Coahuila, Mexico.
| |
Collapse
|
14
|
Wang JC, Wang H. Fenton treatment for flotation separation of polyvinyl chloride from plastic mixtures. Sep Purif Technol 2017. [DOI: 10.1016/j.seppur.2017.06.076] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
15
|
Wang JC, Wang H, Huang LL, Wang CQ. Surface treatment with Fenton for separation of acrylonitrile-butadiene-styrene and polyvinylchloride waste plastics by flotation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 67:20-26. [PMID: 28578857 DOI: 10.1016/j.wasman.2017.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/17/2017] [Accepted: 05/04/2017] [Indexed: 06/07/2023]
Abstract
Surface treatment with Fenton was applied to flotation separation of acrylonitrile-butadienestyrene (ABS) and polyvinylchloride (PVC). After treatment, the floatability of ABS has a dramatic decrease, while the floatability of PVC is not affected. Fourier transform infrared spectroscopy (FT-IR) spectra and X-ray photoelectron spectroscopy (XPS) spectra were recorded to ascertain the mechanism of Fenton treatment. FT-IR and XPS analysis confirms that the introduction of oxygen-containing group occurs on the surface of ABS. The optimum conditions are molar ration (H2O2:Fe2+) 10000, H2O2 concentration 0.4M/L, pH 5.8, treatment time 2min and temperature 25°C, frother concentration 15mg/L and flotation time 3min. Particle sizes and mixing ratios were also investigated. Plastic mixtures of ABS and PVC with different particle sizes and mixing ratios can be effectively separated. The purity of ABS and PVC are up to 100% and 99.78%, respectively; the recovery of ABS and PVC are up to 99.89% and 100%, respectively. A practical, environmentally friendly and effective reagent, namely Fenton, was originally applied to surface treatment of ABS and PVC waste plastics for flotation separation of their mixtures.
Collapse
Affiliation(s)
- Jian-Chao Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
| | - Luo-Luo Huang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Chong-Qing Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| |
Collapse
|
16
|
Wang CQ, Wang H, Huang LL. A novel process for separation of polycarbonate, polyvinyl chloride and polymethyl methacrylate waste plastics by froth flotation. WASTE MANAGEMENT (NEW YORK, N.Y.) 2017; 65:3-10. [PMID: 28400158 DOI: 10.1016/j.wasman.2017.04.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/31/2017] [Accepted: 04/03/2017] [Indexed: 06/07/2023]
Abstract
A novel process was proposed for separation of ternary waste plastics by froth flotation. Pretreatment of plastics with potassium permanganate (KMnO4) solution was conducted to aid flotation separation of polycarbonate (PC), polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA) plastics. The effect of pretreatment parameters including KMnO4 concentration, treatment time, temperature and stirring rate on flotation recovery were investigated by single factor experiments. Surface treatment with KMnO4 changes selectively the flotation behavior of PC, PVC and PMMA, enabling separation of the plastics by froth flotation. Mechanism of surface treatment was studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray photoelectron spectrum (XPS). Effect of frother concentration and flotation time on flotation behavior of plastic mixtures was further studied for flotation separation. The optimized conditions for separation of PC are KMnO4 concentration 2mmolL-1, treatment time 10min, temperature 60°C, stirring rate 300rpm, flotation time 1min and frother concentration 17.5mgL-1. Under optimum conditions, PVC and PMMA mixtures are also separated efficiently by froth flotation associated with KMnO4 treatment. The purity of PC, PVC and PMMA is up to 100%, 98.41% and 98.68%, while the recovery reaches 96.82%, 98.71% and 98.38%, respectively. Economic analysis manifests remarkable profits of the developed process. Reusing KMnO4 solution is feasible, enabling the process greener.
Collapse
Affiliation(s)
- Chong-Qing Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
| | - Luo-Luo Huang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| |
Collapse
|
17
|
Thanh Truc NT, Lee BK. Selective separation of ABS/PC containing BFRs from ABSs mixture of WEEE by developing hydrophilicity with ZnO coating under microwave treatment. JOURNAL OF HAZARDOUS MATERIALS 2017; 329:84-91. [PMID: 28126573 DOI: 10.1016/j.jhazmat.2017.01.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 12/29/2016] [Accepted: 01/16/2017] [Indexed: 06/06/2023]
Abstract
This study reports a simple and facile method to separate plastic wastes of acrylonitrile-butadiene-styrene (ABS) and ABS-based plastics (blends of ABS) in waste electronic and electrical equipment (WEEE) by froth flotation after inducing hydrophilization by ZnO coating under microwave treatment. ABS-based plastics containing brominated flame retardants (BFRs) can release hazardous substances, such as hydrogen bromide and brominated dioxins, during disposal or recycling activities. ABS and ABS-based plastics are typical styrene plastics with similar properties and it is, therefore, difficult to separate them selectively for recycling. We used 2-min microwave treatment to rearrange and change the molecular mobility on the surface of the ZnO-coated ABS with increased hydrophilic surfaces, which eased the selective separation of the ABS/polycarbonate (PC) blend containing BFRs from the remaining plastics. Therefore, the combined ZnO coating and microwave treatments can facilitate the selective separation of ABS/PC blend plastics with a recovery and purity of 100% and 91.7%, respectively, in a short flotation time of 2min. Based on these findings, the combination of ZnO coating-microwave treatment and froth flotation can be applied for the selective separation of ABS-based plastics, leading to improved plastic recycling quality.
Collapse
Affiliation(s)
- Nguyen Thi Thanh Truc
- Department of Civil and Environmental Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan, 680-749, Republic of Korea
| | - Byeong-Kyu Lee
- Department of Civil and Environmental Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan, 680-749, Republic of Korea.
| |
Collapse
|
18
|
Thanh Truc NT, Lee CH, Lee BK, Mallampati SR. Surface hydrophilization of acrylonitrile butadiene styrene by the mild heat treatment for its selective separation to recycling. Sep Purif Technol 2017. [DOI: 10.1016/j.seppur.2016.09.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
19
|
Thanh Truc NT, Lee CH, Lee BK, Mallampati SR. Development of hydrophobicity and selective separation of hazardous chlorinated plastics by mild heat treatment after PAC coating and froth flotation. JOURNAL OF HAZARDOUS MATERIALS 2017; 321:193-202. [PMID: 27619965 DOI: 10.1016/j.jhazmat.2016.09.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 08/25/2016] [Accepted: 09/05/2016] [Indexed: 06/06/2023]
Abstract
Polyvinyl chloride (PVC) containing chlorine can release highly toxic materials and persistent organic pollutants if improperly disposed of. The combined technique of powder activated carbon (PAC) coating and mild heat treatment has been found to selectively change the surface hydrophobicity of PVC, enhancing its wettability and thereby promoting its separation from heavy plastic mixtures included polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS) and acrylonitrile butadiene styrene (ABS) by means of froth flotation. The combined treatments helped to rearrange the surface components and make PVC more hydrophobic, while the remaining plastics became more hydrophilic. After the treatments at 150°C for 80s the contact angle of the PVC was greatly increased from 90.5 to 97.9°. The SEM and AFM reveal that the surface morphology and roughness changes on the PVC surface. XPS and FT-IR results further confirmed an increase of hydrophobic functional groups on the PVC surface. At the optimized froth flotation and subsequent mixing at 150rpm, 100% of PVC was recovered from the remaining plastic mixture with 93.8% purity. The combined technique can provide a simple and effective method for the selective separation of PVC from heavy plastics mixtures to facilitate easy industrial recycling.
Collapse
Affiliation(s)
- Nguyen Thi Thanh Truc
- Department of Civil and Environmental Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan 680-749, Republic of Korea
| | - Chi-Hyeon Lee
- Department of Civil and Environmental Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan 680-749, Republic of Korea
| | - Byeong-Kyu Lee
- Department of Civil and Environmental Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan 680-749, Republic of Korea.
| | - Srinivasa Reddy Mallampati
- Department of Civil and Environmental Engineering, University of Ulsan, Daehakro 93, Namgu, Ulsan 680-749, Republic of Korea
| |
Collapse
|
20
|
Thanh Truc NT, Lee BK. Sustainable and Selective Separation of PVC and ABS from a WEEE Plastic Mixture Using Microwave and/or Mild-Heat Treatment with Froth Flotation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:10580-10587. [PMID: 27602948 DOI: 10.1021/acs.est.6b02280] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study reports simple, selective, and sustainable separation of chlorinated plastic (polyvinyl chloride, PVC) and acrylonitrile butadiene styrene (ABS) containing brominated flame retardants (BFRs) from mixed waste electrical and electronic equipment (WEEE) plastics using microwave and/or mild-heat treatment. Microwave treatment after plastic coating with powdered activated carbon (PAC) selectively increased the hydrophilicity of the PVC surface, which facilitated PVC separation (100% recovery and purity) from the WEEE plastic mixture under the optimum flotation conditions. A further mild-heat treatment for 100 s facilitated selective separation with the highest recovery and purity (100%) of PAC-coated ABS containing BFRs from the remaining plastic mixture due to selective formation of a twisted structure with a lower density than water and the untreated ABS. Mild-heat treatment only of PAC-coated WEEE plastic mixture resulted in successful recovery of (100%) the ABS and PVC. However, the recovered PVC had slightly reduced purity (96.8%) as compared to that obtained using the combined heat and microwave treatments. The combination of both treatments with flotation facilitated selective and sustainable separation of PVC and ABS from WEEE plastics to improve their recycling quality.
Collapse
Affiliation(s)
- Nguyen Thi Thanh Truc
- Department of Civil and Environmental Engineering, University of Ulsan , Daehakro 93, Namgu, Ulsan 680-749, Republic of Korea
| | - Byeong-Kyu Lee
- Department of Civil and Environmental Engineering, University of Ulsan , Daehakro 93, Namgu, Ulsan 680-749, Republic of Korea
| |
Collapse
|
21
|
Wang CQ, Wang H, Gu GH, Lin QQ, Zhang LL, Huang LL, Zhao JY. Ammonia modification for flotation separation of polycarbonate and polystyrene waste plastics. WASTE MANAGEMENT (NEW YORK, N.Y.) 2016; 51:13-18. [PMID: 26965210 DOI: 10.1016/j.wasman.2016.02.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Revised: 02/25/2016] [Accepted: 02/27/2016] [Indexed: 06/05/2023]
Abstract
A promising method, ammonia modification, was developed for flotation separation of polycarbonate (PC) and polystyrene (PS) waste plastics. Ammonia modification has little effect on flotation behavior of PS, while it changes significantly that of PC. The PC recovery in the floated product drops from 100% to 3.17% when modification time is 13min and then rises to 100% after longer modification. The mechanism of ammonia modification was studied by contact angle, and Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements. Contact angle of PC indicates the decline of PC recovery in the floated product is ascribed to an increase in surface wettability. FT-IR and XPS spectra suggest that ammonia modification causes chemical reactions occurred on PC surface. Flotation behavior of ammonia-modified PC and PS was investigated with respect to flotation time, frother concentration and particle sizes. Flotation separation of PC and PS waste plastics was conducted based on the flotation behavior of single plastic. PC and PS mixtures with different particle sizes are separated efficiently, implying that the technology possesses superior applicability to particle sizes of plastics. The purity of PS and PC is up to 99.53% and 98.21%, respectively, and the recovery of PS and PC is larger than 92.06%. A reliable, cheap and effective process is proposed for separation of PC and PS waste plastics.
Collapse
Affiliation(s)
- Chong-Qing Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
| | - Guo-Hua Gu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083 Hunan, China
| | - Qing-Quan Lin
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083 Hunan, China
| | - Ling-Ling Zhang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Luo-Luo Huang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Jun-Yao Zhao
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| |
Collapse
|
22
|
Wang C, Wang H, Fu J, Zhang L, Luo C, Liu Y. Flotation separation of polyvinyl chloride and polyethylene terephthalate plastics combined with surface modification for recycling. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 45:112-117. [PMID: 26253330 DOI: 10.1016/j.wasman.2015.07.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 07/06/2015] [Accepted: 07/30/2015] [Indexed: 06/04/2023]
Abstract
Surface modification with potassium permanganate (KMnO4) solution was developed for separation of polyvinyl chloride (PVC) and polyethylene terephthalate (PET) waste plastics. The floatability of PVC decreases with increasing of KMnO4 concentration, treatment time, temperature and stirring rate, while that of PET is unaffected. Fourier transform infrared (FT-IR) analysis confirms that mechanism of surface modification may be due to oxidization reactions occurred on PVC surface. The optimum conditions are KMnO4 concentration 1.25 mM/L, treatment time 50 min, temperature 60°C, stirring rate 300 r/min, frother concentration 17.5 g/L and flotation time 1 min. PVC and PET with different particle sizes were separated efficiently through two-stage flotation. Additionally, after ultrasonic assisted surface modification, separation of PVC and PET with different mass ratios was obtained efficiently through one-stage flotation. The purity and the recovery of the obtained products after flotation separation are up to 99.30% and 99.73%, respectively. A flotation process was designed for flotation separation of PVC and PET plastics combined with surface modification. This study provides technical insights into physical separation of plastic wastes for recycling industry.
Collapse
Affiliation(s)
- Chongqing Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China.
| | - Jiangang Fu
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Lingling Zhang
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Chengcheng Luo
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| | - Younian Liu
- School of Chemistry and Chemical Engineering, Central South University, Changsha, 410083 Hunan, China
| |
Collapse
|
23
|
Wang CQ, Wang H, Fu JG, Liu YN. Flotation separation of waste plastics for recycling-A review. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 41:28-38. [PMID: 25869841 DOI: 10.1016/j.wasman.2015.03.027] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 03/16/2015] [Accepted: 03/18/2015] [Indexed: 06/04/2023]
Abstract
The sharp increase of plastic wastes results in great social and environmental pressures, and recycling, as an effective way currently available to reduce the negative impacts of plastic wastes, represents one of the most dynamic areas in the plastics industry today. Froth flotation is a promising method to solve the key problem of recycling process, namely separation of plastic mixtures. This review surveys recent literature on plastics flotation, focusing on specific features compared to ores flotation, strategies, methods and principles, flotation equipments, and current challenges. In terms of separation methods, plastics flotation is divided into gamma flotation, adsorption of reagents, surface modification and physical regulation.
Collapse
Affiliation(s)
- Chong-qing Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - Jian-gang Fu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - You-nian Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| |
Collapse
|
24
|
Wang CQ, Wang H, Liu YN. Separation of polyethylene terephthalate from municipal waste plastics by froth flotation for recycling industry. WASTE MANAGEMENT (NEW YORK, N.Y.) 2015; 35:42-47. [PMID: 25449606 DOI: 10.1016/j.wasman.2014.09.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 09/24/2014] [Accepted: 09/24/2014] [Indexed: 06/04/2023]
Abstract
Recycling is an effective way to manage plastic wastes and receives considerable attention. Since plastic mixtures are difficult to recycle because of their intrinsic characteristics, separation of mixed plastics is the key problem for recycling. Separation of polyethylene terephthalate (PET) from municipal waste plastics (MWP) by froth flotation combined with alkaline pretreatment was investigated for recycling industry. The effect of process variables was estimated by L9 (3(4)) orthogonal array of experiments and single factor experiments. The optimum conditions of alkaline pretreatment are 10 wt% sodium hydroxide, 20 min and 70°C. After alkaline pretreatment under optimum conditions, flotation separation PET from acrylonitrile-butadiene-styrene, polystyrene, polycarbonate or polyvinyl chloride was achieved with high purity and efficiency. The purity of PET is up to 98.46% and the recovery is above 92.47%. A flow sheet of separation PET from MWP by a combination of froth flotation and sink float separation was designed. This study facilitates industrial application of plastics flotation and provides technical insights into recycling of waste plastics.
Collapse
Affiliation(s)
- Chong-Qing Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China
| | - Hui Wang
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China.
| | - You-Nian Liu
- School of Chemistry and Chemical Engineering, Key Laboratory of Resources Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha, 410083 Hunan, China
| |
Collapse
|