End-of-Life Heavy Metal Releases from Photovoltaic Panels and

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End-of-Life Heavy Metal Releases from Photovoltaic Panels and Quantum Dot Films: Hazardous Waste Concerns or Not? Frank Christopher Brown, Yuqiang Bi, Shauhrat Chopra, Kiril D. Hristovski, Paul Westerhoff, and Thomas L. Theis ACS Sustainable Chem. Eng., Just Accepted Manuscript • Publication Date (Web): 04 Jun 2018 Downloaded from http://pubs.acs.org on June 4, 2018

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ACS Sustainable Chemistry & Engineering

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End-of-Life Heavy Metal Releases from Photovoltaic Panels and Quantum Dot Films:

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Hazardous Waste Concerns or Not?

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Frank C. Brown1, Yuqiang Bi2, Shauhrat S. Chopra3, Kiril D. Hristovski1, *, Paul

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Westerhoff 2, Thomas L. Theis4

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1

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Sonoran Arroyo Mall, Mesa, AZ, 85212

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2

The Polytechnic School, Ira A. Fulton Schools of Engineering, Arizona State University, 7171

Nanosystems Engineering Research Center for Nanotechnology-Enabled Water Treatment, School of

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Sustainable Engineering and the Built Environment, Ira A. Fulton Schools of Engineering, 660

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S. College Avenue, Arizona State University, Tempe, AZ 85287-3005

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3

13

Kowloon, Hong Kong

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4

15

Taylor Street, Chicago, IL 60612-4224

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* Corresponding author: 7171 Sonoran Arroyo Mall, Mesa, AZ 85212-2180; email:

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[email protected]

School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue,

Institute for Environmental Science and Policy, University of Illinois at Chicago, 2121 West

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ACS Paragon Plus Environment

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Abstract

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To determine if there are potential concerns related to the environmental end-of-life

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impacts of photovoltaic (PV) or quantum-dot display (QD) technologies, the goal of this study

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was to assess the magnitude of heavy metal leaching using simulated landfill methodologies

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from devices in an attempt to forecast the lifecycle environmental impacts of subsequent

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generations QD-enabled PV technologies. The underlying hypotheses are (H1) existing PV and

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QD thin-film technologies do not release heavy metals at concentrations exceeding RCRA or

27

State of California regulatory limits; and (H2) the disposal of PV and QD thin-film technologies

28

does not exceed Land Disposal Restrictions (LDR). Three task-oriented objectives were

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completed: (O1) five representative PV panels and two representative thin-film displays with QD

30

technology were obtained from commercial sources; (O2) RCRA Toxicity Characteristics

31

Leaching Procedure (TCLP) tests and California Waste Extraction Tests (WET) were conducted

32

in addition to microwave-assisted nitric acid digestion; and (O3) results were compared to the

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existing regulatory limits to examine the potential environmental end-of-life concerns. The heavy

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metal concentrations obtained from PV panels and QD thin-film displays when exposed to

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simulated landfill environments and extreme case leaching scenarios were generally several

36

orders of magnitude lower than the promulgated standards and probably not of major concerns

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related to end-of-life safe disposal of these commercially available products. With exception to

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the findings for lead under the RCRA rules, the results confirmed that PV and QD thin-film

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technologies do not release heavy metals at concentrations exceeding RCRA or State of

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California characteristic hazardous waste regulatory limits. However, lead, mercury, and

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potentially other heavy metal releases have to be monitored to ensure that the disposal of this

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type of waste is in compliance with RCRA’s LDR requirements and universal treatment

43

standards because the second underlying hypothesis could not be completely supported for the

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leaching of these heavy metals. It could be anticipated that newer and more sophisticated

45

soldering materials and approaches in the next generation of PV panels would significantly

46

reduce the use of RCRA heavy metals or nanomaterials. However, although the generated data is

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limited to these representative PV and QD technologies and as such should not be considered

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applicable to the entire gamete of present-day technologies, these findings suggest that their

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release from future PV QD technologies would likely be greater from non-end-of-life processes,

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than from traditional land disposal routes.


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KEYWORDS: Photovoltaic Panels, Land Disposal, TCLP, WET, nanoparticles, thin films

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Introduction

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Driven by the ever-increasing energy needs, photovoltaic (PV) technology has entered

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the global market on a grand scale in the last couple of decades. The world-wide electric

63

generation capacity from PV technology has more than doubled from about 30 GW in 2011 to

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more than 90 GW in 2017, with a significant projected increase in 2018.1 According to the

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United States Department of Energy’s (USDOE) Office of Energy Efficient and Renewable

66

Energy (EERE), over 270 million PV panels were installed across the world in 2016. With each

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panel weighing between 10-25 kg, this quantity could be conservatively translated to roughly 4

68

billion kg of PV panels that will have to be decommissioned by 2036 assuming a 20-year

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operational life span.2 It is anticipated that these panels will be replaced with more advanced PV

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technologies that exhibit improved quality, durability, and energy conversion efficiency.

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Other thin film technologies are also rapidly entering the market. Recent advances in

72

nanomaterial-based quantum dot technology (QD), which have paved the way for the

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development and commercialization of thin-film displays, offer unique promises in their ability

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to replace the existing PV technology and address the overarching goals related to improved

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performance, durability, and lowered costs.3 During the last decade, the QD associated thin-film

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technology markets have been exhibiting steady increases driven by the growing demand for

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high resolution and color quality of displays used in computers, TV sets, tablets, and smart

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telephones.4 Latest developments in PV research imply that the same QD thin-film display

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technology has the potential to replace the existing silicon based technology3. The much shorter

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lifespan of these QD devices (years instead of decades), coupled with the decreasing costs of

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fabrication, raises concerns that the existing PV panel decommissioning and disposal rates will

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increase if QD technology is to partially or fully replace the existing PV technology. Considering

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that PV panels and QD displays both employ encapsulation of heavy metal containing materials

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into an inert matrix (e.g. polymer, silica, etc.)5,6, and these heavy metals are known toxins or

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carcinogens, strong end-of-life correlations could be derived from their waste analyses. These

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analyses have the ability to either raise or relieve concerns related to leaching of heavy metals

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and Resource, Conservation and Recovery Act (RCRA) hazardous classifications, which could

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substantially increase the costs associated with manufacturing, decommissioning, and disposal of

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the new nanomaterial-enabled PV and display technologies.7 To determine if there are any


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concerns related to the environmental end-of-life impacts of these technologies, the goal of this

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study was to assess the magnitude of heavy metal leaching from existing PV and QD

92

technologies in an attempt to forecast the potential environmental impacts of subsequent

93

generations QD-enabled PV technologies. The underlying hypotheses are (H1) existing PV and

94

QD thin-film technologies do not release heavy metals at concentrations exceeding RCRA or

95

State of California regulatory limits;8 and (H2) the disposal of PV and QD thin-film technologies

96

does not exceed Land Disposal Restrictions (LDR). To address the goal and test these

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hypotheses, three objectives were completed: (O1) five representative PV panels and two

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representative thin-film displays with QD technology were obtained from commercial sources;

99

(O2) RCRA Toxicity Characteristics Leaching Procedure (TCLP) tests and California Waste

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Extraction Tests (WET) were conducted in addition to nitric acid microwave assisted digestion;

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and (O3) results were compared to the existing regulatory limits to examine the potential

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environmental end-of-life concerns.

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Methodology

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Classification, Identification, and Preparation of Commercial Photovoltaic Panels and Quantum

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Dots Thin-film Displays for Metal Extraction

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Five commercial PV panels from three manufacturers were obtained for this study. As

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summarized in Table 1, three of these PV panels were fabricated of monocrystalline cells and

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two were fabricated of polycrystalline cells. Only the PV cells of the modules were examined

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for leaching of heavy metals. The output terminals, aluminum frames and the other plastic

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support elements, which could be easily disassembled from the modules, were not considered in

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this study.

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Similarly, two commercially available QD thin-film displays were obtained as

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summarized in Table 1. Each display employs a type of quantum dots that are commercially used

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in thin-film technology and employ the similar elements used to develop then next generation

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QD enabled PV thin-film technology.9 Because both products used on-surface QD display

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technology, where sheets of QD films cover the entire display area,10 an attempt was made to

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separate the QD films from the display plate, and assess the heavy metal leaching only from

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them. Unfortunately, it was impossible to separate the QD containing thin-film sandwiched

119

between two barrier layers of the Samsung display plate without employing aggressive agents,



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which would have skewed the results. Therefore, the heavy metal leaching from the Samsung

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display thin-film alone was not conducted.

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Table 1. Photovoltaic panels and Quantum Dot Display Manufacturers, Models, and Types Designation Manufacturer

Model No.

Module Type

PV1

Canadian Solar

CSP6 220A

Monocrystalline

PV2

Suntech

STP 170 S-24

Monocrystalline

PV3

Sharp

NT 175U1

Monocrystalline

PV4

Sharp

NE 175U1

Polychristalline

PV5

Sharp

ND 167U3A

Polychristalline

QD1

Amazon

Kindle Fire HDX 7

CdSe/ZnS

QD2

Samsung

60” 4K SUHD

InP/ZnS

124 125

Simulated Landfill Leaching and Microwave-assisted Acid Extraction of Heavy Metals from

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Photovoltaic Panels and Quantum Dot Displays

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US EPA Toxicity Leaching Characteristic Procedure SW-846 Method 131111 and

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California Waste Extraction Test12 were employed to determine whether heavy metal

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concentrations in the leachate exceed toxicity characteristic hazardous waste limits. Furthermore,

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to assess the maximum leachable heavy metal potential, the PV panel and QD display samples

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were microwave digested in concentrated nitric acid.13

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In brief, the sample physical sizes were reduced by cutting ~ 1 inch (~ 2.5 cm) square

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pieces with 2.5 inch (6.25 cm) bolt cutter. The sample particle sizes were further reduced by

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employing mortar and pestle grinding techniques to achieve the particle sizes as mandated by the

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methods. US Mesh #10 sieve was for particle size separation as required per the standard

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leaching methods. Samples were collected and processed in triplicates to assess variability.

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Method prescribed sample mass to extraction fluid volume were used. Specifically, 1:20 mass-

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to-leaching (extraction) fluid #1 were used for the TCLP, while 1:10 mass-to-leaching

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(extraction) fluid were used for the California WET. These mass-to-leaching ratios were used to


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convert the reported heavy metal leachate concentrations (mg/L) into mass of leached heavy

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metal per mass of material (mg/g) descriptors. Microwave digestion was conducted with 0.6 ±

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0.1 g of dry sample and 12 mL ultra pure nitric acid, and no hydrofluoric acid as suggested by

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SW-846 Method 3050B. Microwave digestion was performed using an Anton Paar Multiwave

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3000 Microwave Digestion System. Samples were filtered thought GFF or 0.45 µm filter, as per

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method requirements. Because the thin-film could not be separated from the Samsung display, a

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fraction of entire display composite was ashed and then digested in nitric acid, while only on the

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Kindle thin-film was subjected to the same treatment. The ashing/digestion approach was

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employed for two reasons: (1) to increase the very low content of heavy metals in the sample

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(i.e. concentrate the sample); and (2) simulate possible worst-case scenario.

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All laboratory glassware and plasticware was washed and sonicated in 10% nitric acid,

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and minimum triple rinsed with ultrapure water (18.2 MΩ/cm) before use. Samples were

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preserved in 2% trace analysis nitric acid solution and stored at 4 °C before analysis. Multi-

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element analysis was performed using Inductively Coupled Plasma (ICP) Optical Emission

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Spectroscopy (OES) (Thermo iCAP 6300) or ICP Mass Spectroscopy (MS) (Thermo XSeries II)

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and minimum five point calibration curves.

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Results and Discussion

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In leachates from the PV panels only 6 (Pb, Zn, Ba, Ni, Cr, Hg) of 34 monitored chemical

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elements were above their corresponding method detection limits (MDLs). Figure 1 summarizes

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these findings. Similar to the results obtained by Krishnamurthy,14 lead exhibited the highest

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concentrations for all of the detected metals with concentrations ranging between 0.7 and 18

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mg/L, while the other elements exhibited concentrations that are generally between 0.01 and 0.2

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mg/L. Two PV panels, Canadian Solar and Suntech, exceeded the 5 mg/L RCRA characteristic

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hazardous waste limits for lead. Leaching of lead is likely attributed to older soldering materials

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that have high lead content, and do not necessarily originate from the silica-based cells.

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Interestingly, however, the leached lead from all PV panels exceeded the Universal Treatment

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Standard (UTS) of 0.69 mg/L TCLP promulgated under the RCRA Land Disposal Restrictions

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Rule.15 None of the other metals exceeded their respected UTS values although mercury TCLP

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concentrations were within 80% of the 0.025 mg/L regulatory limit.



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In contrast, the California WET method generated leachate with much lower

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concentrations for lead than the RCRA regulatory limits. Specifically, the lead concentrations for

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all PV panels were generally < 2 mg/L in all WET leachates, which was significantly lower than

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the 5.0 mg/L RCRA hazardous waste limit for lead. This unexpected difference could be

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attributed to the different solubility of lead in citric and acetic acid environments and may initiate

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regulatory debate related to standardizing hazardous waste testing.16 When normalized per gram

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of waste material as per California Hazardous waste regulation requirements, none of the PV

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panels released heavy metals at concentrations that exceed the TTLC regulatory limits (Figure

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2). All PV panels, however, exceeded these limits for lead and silver when they were microwave

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digested in nitric acid as illustrated in Figure 3. Although these nitric acid-digestion scenarios are

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completely unrealistic they demonstrate the worst-case heavy metal release from present day PV

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panels and may help understand the potential risks from unsafe disposal scenarios.

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Figure 4 summarizes the heavy metal concentrations from the TCLP tests for the thin-

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film QD displays. In the leaching fluid from both TV and Kindle QD films, indium and cadmium

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exhibited concentrations < 0.2 µg/L, while Zn concentrations were < 2 mg/L. All of the tested

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samples exhibited heavy metal concentrations that were orders of magnitude below their

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corresponding regulatory RCRA limits. Similarly, these heavy metal concentration values were

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also lower than even their corresponding universal treatment standards.15 As illustrated in Figure

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5, identical trends were observed when the WET data was compared to the California TTLC

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regulatory limits. For all elements, the leached heavy metal concentrations were orders of

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magnitude below the regulatory limits. This is not surprising considering strong PET matrix

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contained the heavy metal QDs. Such low concentrations of heavy metals in the leachates are not

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completely unexpected considering that the thin-film QDs content is extremely small., the Kindle

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thin-film contained 315 ± 12 µg Cd and 446 ± 12 µg Zn per gram of thin film as determined by

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acid digestion. For the Samsung display, the zinc content was an order of magnitude greater than

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the Kindle thin-film. The display released 4336 ± 76 µg Zn and 71 ± 3 µg In per gram of display,

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which was in accordance with the results from the corresponding simulated landfill leaching

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tests. Nonetheless, these values are significantly lower than the corresponding land disposal

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regulatory limits for elements with promulgated standards.


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The heavy metal concentrations obtained from representative PV panels and QD thin-

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film displays when exposed to simulated landfill environments and extreme case leaching

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scenarios appear relatively small to raise any concerns related to end-of-life safe disposal of

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these commercially available product. The primary reason for these low heavy metal

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concentrations stems from prohibitive effect of the matrix on leaching of heavy metal elements

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and quantum dots. Even under extremely unrealistic scenarios, the heavy metal release

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concentrations were sufficiently low to warrant any concerns. Only the release of lead was

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concerning because a couple of monocrystalline PV panels exceeded the RCRA mandated

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regulatory limits although the crystallinity appeared not to have any significant effects on the

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release of heavy metals. However, the understanding that this lead release in a TCLP matrix

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could be attributed to the older generation soldering materials could alleviate these concerns. It

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could be anticipated that newer and more sophisticated soldering materials and approaches in the

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next generation of PV panels would significantly reduce the use and release of lead at end-of-

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life.17

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Conclusions and Implications

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With exception to the findings for lead under the RCRA rules, the results from this

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assessment of heavy metal release from commercially available PV panels and QD thin-film

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displays, confirmed the first underlying hypothesis that existing PV and QD thin-film

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technologies do not release heavy metals at concentrations exceeding RCRA or State of

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California regulatory limits. The PV cell and QD thin-film technologies will likely maintain their

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integrity at end-of-life land disposal scenarios because of the heavy metal material encapsulation

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in glass or polymer materials.18 However, lead, mercury, and potentially other heavy metal

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releases have to be monitored to ensure that the disposal of this type of waste is in compliance

221

with RCRA’s LDR requirements and universal treatment standards because the second

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underlying hypothesis could not be completely supported for the leaching of these heavy metals.

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This conclusion does not, however, imply that the future PV QD thin-film technologies would

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not overcome this sustainability issue considering that the advent of nanotechnology is expected

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to lead towards novel and greener fabrication processes stemming from material minimization

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and energy efficiency.



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Although recycling of PV panels and QD thin film displays could minimize or even

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completely eliminate the release of heavy metals,19 other end-of-life scenarios like incineration

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could significantly increase their release into the environment via different routes. Incineration of

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these types of materials is likely to produce wastes (ashes) that contain higher content of

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hazardous metals that may drive this waste over the RCRA and California hazardous waste

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limits.20 At this point, it could be anticipated that the exposure to heavy metals or nanomaterial

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from the PV and QD technologies would likely increase as result of non-end-of-life processes,

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like manufacturing.21 However, the sheer volume of this type of waste, once these technologies

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are decommissioned, warrants further monitoring of the potential problem, especially in light of

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the looming replacement of large quantities of the first generation of PV panels and the rapid

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advancement of the thin-film QD technology.

238 239

Acknowledgements

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The authors express their gratitude to Salt River Project for partial funding and support of this

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study. Partial funding was provided from the US Environmental Protection Agency through the

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STAR program (RD83558001)

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Supporting Information. Supporting information contains tables with all the values for the

244

obtained measurements.

245 246 247


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References

249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292

(1) Margolis, R.; Feldman, D.; Boff, D. Solar Industry Update: Q4 2016/Q 2017; Sun Shot, U.S. Department of Energy, April 2017. (2) Fu, R.; Feldman, D.; Margolis, R.; Woodhouse, M.; Ardani, K. U.S. Solar Photovoltaic System Cost Benchmark: Q1 2017; Technical Report NREL/TP-6A20-68925: National Renewable Energy Laboratory, September 2017. (3) Tang, J.; Sargent, E.H. Infrared Colloidal Quantum Dots for Photovoltaics: Fundamentals and Recent Progress. Adv. Mater. 2010, 23(1), 12-29, DOI 10.1002/adma.201001491. (4) Shirasaki, Y.; Supran, G.J.; Bawendi, M.G.; Bulovic, V. Emergence of Colloidal Quantum-dot Light-emitting Technologies. Nat. Photonics 2013, 7(1), 13-23, DOI 10.1038/nphoton.2012.328. (5) Wiesmeier, C.; Haedrich, I.; Weiss, K.A. Overview of PV Module Encapsulation Materials. Photovoltaics Int. 2013, 19, 85-92. (6) Rowe, D.; Lyons, C.; Jones, S.; Schleusner, S.; Johnson, J.; Roehrig, M. Barrier Film Manufacturing for OLED Solid State Lighting, Presented at Department of Energy SSL Workshop, Long Beach, CA, February 1st, 2017. (7) Theocharis, T.; Frantzeskaki, N.; Gekas, V. Environmental Impacts from the Solar Energy Technologies. Energ. Policy 2005, 33, 289-96, DOI 10.1016/S03014215(03)00241-6. (8) Resource Conservation and Recovery Act Subpart D, 40 C.F.R. § 268.40; Electronic Code of Federal Regulations, 2018. https://www.ecfr.gov/cgi-bin/textidx?SID=d5e300ba686068914b59636e715c709d&mc=true&node=pt40.29.268&rgn=div 5#se40.29.268_140 (accessed April 13, 2018). (9) Polycrystalline Thin-Film Photovoltaics; National Renewable Energy Laboratory, https://www.nrel.gov/pv/polycrystalline-thin-film-photovoltaics.html (accessed Apr 13, 2018). (10) Manders, J.R.; Bera, D.; Qian, L.; Holloway, P.H. Quantum Dots for Displays and Solid State Lighting. In Materials for Solid State Lighting and Displays; Kitai, A., Ed.; Wiley Series; NJ, USA, 2016; pp 31-90. (11) SW-846 Method 1311: Toxicity Characteristic Leaching Procedure; United States Environmental Protection Agency, US, 1992. (12) California Code of Regulations, 22 CA ADC Appendix II; Barclays Official California Code of Regulations; Title 22. Social Security; Division 4.5. Environmental Health Standards for the Management of Hazardous Waste; Chapter 11. Identification and Listing of Hazardous Waste; Article 5. Categories of Hazardous Waste. (13) SW-846 Test Method 3050B: Acid Digestion of Sediments, Sludges, and Soils; United States Environmental Protection Agency, US, 1996. (14) Krishnamurthy, R. Standardized Sample Extraction Procedure for TCLP Testing of PV Modules, Master of Science Thesis, Arizona State University, AZ, 2017. (15) Resource Conservation and Recovery Act Subpart D, 40 C.F.R. § 268.48, Land Disposal Restrictions; Electronic Code of Federal Regulations, 2018. https://www.ecfr.gov/cgibin/textidx?SID=d5e300ba686068914b59636e715c709d&mc=true&node=pt40.29.268&rgn=div 5#se40.29.268_143 (accessed April 13, 2018).



293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312

(16) Lincoln, J.D.; Ogunseitan, O. A.; Shapiro, A. A.; Saphores, J.-D. M. Leaching Assessments of Hazardous Materials in Cellular Telephones. Environ. Sci. Technol. 2007, 41(7), 2572–2578, DOI 10.1021/es0610479. (17) Tsuo, Y.S.; Gee, J.M.; Menna, P.; Strebkov, D.S.; Pinov, A.; Zadde, V. Environmentally Benign Silicon Solar Cell Manufacturing, Presented at 2nd World Conference and Exhibition on Photovoltaic Solar Energy Conversion, Vienna, Austria, July 6-10, 1998. (18) Cyrs, W.D.; Avens, H.J.; Capshaw, Z.A.; Kingsbury, R.A.; Sahmel, J.; Tvermoes, B.E., Landfill Waste and Recycling: Use of a Screening-Level Risk Assessment tool for Endof-Life Cadmium Telluride (CdTe) Thin-Film Photovoltaic (PV) Panels, Energ. Policy 2014, 68, 524-533, DOI 10.1016/j.enpol.2014.01.025. (19) Kemp, K.K.; Almakhlooq, R. Photovoltaic: Life Cycle Analysis and End of Life Management for Material Reuse and Waste Recycling, Presented at Renewable Energy World International Conference, Orlando, FL, USA, December 13-15, 2016. (20) Latunussa, C.E.L.; Ardente, F.; Blengini, G.A.; Mancini, L., Life Cycle Assessment of an Innovative Process for Crystalline Silicon Photovoltaic Panels. Sol. Energ. Mat. Sol. C. 2016, 156, 101-111, DOI 10.1016/j.solmat.2016.03.020. (21) Fthenakis, V.; Zweibel, K. CdTe PV: Real and Perceived EHS Risks, Presented at National Center for Photovoltaics and Solar Program Review Meeting, Denver, CO, March 24-26, 2003.

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Figures Sharp ND 167U3A Canadian Solar UTS Regulatory Limits

Leached metal concentration in TCLP tests (mg metal/g panel)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Sharp NE 170U1 Suntech

Sharp NT 175 U1 RCRA Regulatory Limits

10

1

0.1

0.01

0.001

0.0001

0.00001 Pb

315

Zn

Ba

Ni

Cr

Hg

316

Figure 1. Heavy metals released during the five evaluated photovoltaic panels and the

317

corresponding Resource Conservation and Recovery Act (RCRA) toxicity characteristic

318

hazardous waste limits (RCRA regulatory Limits) and RCRA Land Disposal Restrictions

319

Universal Treatment Standards (UTS regulatory limits). The error bars represent one standard

320

deviation.

321 322 323



324 325 Sharp ND 167U3A Canadian Solar

Leached metal concentration in WET tests (mg metal/g panel)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Sharp NT 175 U1 TTLC Regulatory Limits

10 1 0.1 0.01 0.001 0.0001 0.00001

326

Pb

Zn

Ba

Ni

Cr

Hg

327

Figure 2. Heavy metals released during the Waste Extraction Test (WET) for the five evaluated

328

photovoltaic panels and the corresponding California Hazardous waste regulation requirements

329

(TTLC regulatory limits). Error bars represent one standard deviation.

330 331 332


Page 15 of 18

333 Sharp ND 167UA Canadian Solar

Leached metal concentration in microwave digestion tests (mg metal/g panel)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60



Sharp NT 175 U1 Universal Treatment Standard

1

0.1

0.01

0.001

0.0001

0.00001

334

Pb

Ag

Zn

Ni

Hg

335

Figure 3. Heavy metals released during microwave digestion for the five evaluated photovoltaic

336

panels and the corresponding RCRA Land Disposal Restrictions Universal Treatment Standards.

337

Error bars represent one standard deviation.

338 339



340 10000

TCLP Leached Heavy-metals (ug/L)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 18

Cd

In

Zn

1000 100 10 1 0.1 0.01 TV (Film)

TV (Display)

Kindle (Film)

Kindle (Display)

RCRA

UTS

341 342

Figure 4. Heavy metal concentrations from the TCLP tests for the two thin-film displays and the

343

corresponding Resource Conservation and Recovery Act (RCRA) toxicity characteristic

344

hazardous waste limits (RCRA regulatory Limits) and RCRA Land Disposal Restrictions

345

Universal Treatment Standards (UTS regulatory limits). The error bars represent one standard

346

deviation.

347


Page 17 of 18

348 349 350 Cd

In

Zn

10000000

WET Leached Heavy-metals (ug metal/g material)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


1000000 100000 10000 1000 100 10 1 0.1 TV (Film)

TV (Display)

Kindle (Film)

Kindle (Display)

TTLC

351 352 353

Figure 5. Heavy metals released during the Waste Extraction Test (WET) for two evaluated thin-

354

film displays and the corresponding California Hazardous waste regulation requirements (TTLC

355

regulatory limits). Error bars represent one standard deviation.

356



357

Table of Contents Use Only

358

359 360 361 362

Synopsis

363

Development of new nano-enabled photovoltaic technologies necessitates understanding of their

364

end-of-life implications to ensure adequate environmental protection through implementation of

365

sustainable waste management practices.


Page 18 of 18

End-of-Life Heavy Metal Releases from Photovoltaic Panels and

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