PROCESS FOR RECYCLING CONTAMINATED SOLID MATERIALS AND PURIFICATION OF GASES

Abstract

A process for recycling contaminated solid material is provided. The process comprises heating the material yielding a solid phase, an oil phase, and a gas phase. Prior to being heated, the material is subjected to a pre-treatment involving a dehalogenation agent (DHA). The gas phase obtained is further subjected to a purification treatment. The DHA agent used is regenerated using a regeneration agent (RGA) and further re-used in the process.

Claims

1. A process for recycling contaminated solid material, comprising heating the material yielding a solid phase, an oil phase, and a gas phase, wherein the material is subjected to a pre-treatment involving a dehalogenation agent (DHA) prior to the heating.

2. A process according to claim 1, wherein the heating is performed using a technique which is microwave-pyrolysis, ultrasound, electromagnetic waves at other frequencies than microwave frequencies, electric field, magnetic field, plasma, or a combination thereof.

3. A process according to claim 1, further comprising subjecting the gas phase to a purification treatment involving a further dehalogenation agent yielding a purified gas and a reacted dehalogenation agent.

4. A process according to claim 3, wherein: the process further comprises subjecting the reacted dehalogenation agent to a regeneration process yielding a regenerated dehalogenation agent and/or; the regeneration process involves use of a regeneration agent comprising an acid compound or proton donor: optionally the acidic compound is an inorganic acid (HCl or H.sub.2SO.sub.4) or an organic acid; and/or the regenerated dehalogenation agent is directed for re-use in the pre-treatment of the material and/or in the purification treatment of the gas phase; and/or the process further comprises cleaning the contaminated solid material prior to the pre-treatment; and/or the pre-treatment of the material is conducted at ambient temperature or a higher temperature.

5.-8. (canceled)

9. A process according to claim 3, wherein the DHA used in the pre-treatment step and the further DHA used in the gas purification are the same or are different.

10. A process according to claim 1, wherein: the pre-treated material comprises reduced amounts of compounds containing Br, Cl, F, Co, and Pb when compared to an untreated material; and/or the purified gas is substantially free of chemicals of concern (CoCs) including acidic gases, volatile organic compounds (VOCs), and sulfur-containing compounds; optionally the acidic gases are halogenated gases including HCl, HBr, and HF; optionally the VOCs are propylene, 1,3-butadiene, chloromethane, bromomethane, chloroethane, and vinyl chloride; optionally the sulfur-containing compounds are sulfur oxides (SOx); and/or the oil phase comprises monomers of degraded raw materials, which are classified into low boiling point oils such as gasoline (optionally in an amount of about 63.68%) and medium boiling point oils such as diesel (optionally in an amount of about 20.08%).

11.-12. (canceled)

13. A process for recycling a contaminated plastic material, comprising the steps of: (a) subjecting the material to a pre-treatment involving a dehalogenation agent (DHA) to yield a pre-treated material; (b) subjecting the pre-treated material to a heating process to yield a solid phase, an oil phase, and a gas phase; (c) separating the solid phase, the oil phase, and the gas phase; (d) subjecting the gas phase to a purification treatment involving a further dehalogenation agent (DHA) to yield a purified gas and a reacted DHA; (e) separating the purified gas and the reacted DHA; (f) subjecting the reacted DHA to a regeneration process to yield a regenerated DHA; and (g) directing the regenerated DHA for use at steps (a) and/or step (d).

14. (canceled)

15. A process according to claim 1, wherein the dehalogenation agent comprises an organophosphorus compound.

16. A process according to claim 1, wherein the dehalogenation agent comprises a phosphoric acid ester of general formula I below ##STR00003## wherein R.sub.1 and R.sub.2 are each independently C.sub.1 to C.sub.20 a linear or branched, cyclic or non-cyclic, saturated or unsaturated alkyl group, optionally comprising a heteroatom which is O, S or N; optionally R.sub.1 and R.sub.2 are each independently a C.sub.8 to C.sub.20 or a C.sub.8 to C.sub.16 or a C.sub.16 a linear or branched, cyclic or non-cyclic, saturated or unsaturated alkyl group, optionally comprising a heteroatom which is O, S or N.

17. (canceled)

18. A process according to claim 1, wherein the dehalogenation agent comprises di-(2-ethylhexyl)phosphoric acid (DEHPA or HDEHP) outlined below ##STR00004##

19. A process according to claim 1, wherein the dehalogenation agent comprises a compound selected from the group consisting of: di-(2-ethylhexyl) phosphoric acid, bis(2-ethylhexyl) hydrophosphoric acid, di-(2-ethylhexyl) orthophosphoric acid, O,O-bis(2-ethylhexyl)phosphoric acid, orthophosphoric acid 2-ethylhexyl alcohol, phosphoric acid di(2-ethylhexyl) ester, and Hostarex PA 216™.

20. A process according to claim 1, which yields a clean solid material, an oil comprising monomers of the raw material, and a purified gas substantially free of acidic gases, volatile organic compounds, and sulfur-containing compounds.

21. A process according to claim 1, wherein the contaminated solid material is a contaminated plastic material; optionally the contaminated solid material is an electronic waste (E-waste) plastic material.

22. (canceled)

23. A process according to claim 1, wherein the heating is performed using microwave-pyrolysis.

24. (canceled)

25. A process according to claim 23, wherein: a microwave absorber is added to the material prior to performing the microwave-pyrolysis; optionally the microwave absorber is a carbon-based compound such as SiC or carbon; and/or the microwave absorber and the material are melted prior to performing the microwave-pyrolysis; optionally, melting is performed using a technique which is microwave heating, conventional heating, extrusion, or a combination thereof.

26.-28. (canceled)

29. A process for purifying a gas emission, comprising allowing the gas emission to react with a dehalogenation agent (DHA) yielding a purified gas and a reacted DHA, and separating the purified gas and reacted DHA.

30. A process according to claim 29, further comprising: subjecting the reacted DHA to a regeneration process to yield a regenerated DHA; and/or re-using the regenerated DHA in the process.

31. (canceled)

32. A process according to claim 29, wherein the gas emission is from a facility for combustion of E-waste, organic waste, oil, or coal; optionally the gas emission is from a facility for recycling contaminated solid materials such as contaminated plastic material and contaminated electronic waste (E-waste) plastic materials.

33. (canceled)

34. A system adapted to perform the process as defined in claim 1.

35. An industrial facility embodying the system as defined in claim 34.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the appended drawings:

[0023] FIG. 1: Schematic diagram outlining the process according to the invention.

[0024] FIG. 2: Flow chart outlining the experimental procedure applied in the pre-treatment.

[0025] FIG. 3: Flow chart outlining the experimental procedure used in the microwave-pyrolysis and the gas purification step.

[0026] FIG. 4: Image showing the regenerated DHA floating on the surface of the liquid.

[0027] FIG. 5: SEM band characterization of the untreated heavy fraction plastic. Note: The Lithium band is associated with the X-ray detector window.

[0028] FIG. 6: FT-IR spectrum of the untreated feedstock.

[0029] FIG. 7: SEM images of (A) untreated feedstock; (B) pre-treated feedstock obtained from pre-treatment using DHA at 25° C.; (C) pre-treated feedstock obtained from pre-treatment using DHA at 60° C.; (D) pre-treated feedstock obtained from pre-treatment using toluene-DHA.

[0030] FIG. 8: Investigation on the removal efficiency of chemicals of concern with different pre-treatment conditions. (A) untreated feedstock (solid); (B) pre-treated feedstock obtained from pre-treatment using DHA at 25° C. (dotted); (C) pre-treated feedstock obtained from pre-treatment using DHA at 60° C. (dashdot); (D) pre-treated feedstock obtained from pre-treatment using toluene-DHA (longdash).

[0031] FIG. 9: FT-IR spectra of untreated (solid), pre-treated with ECOC (emulsion-containing organophosphoric compound) at 25° C. (dotted), and pre-treated with ECOC at 60° C. (dotdash) for 6 hours in the range of 650-1000 cm.sup.−1.

[0032] FIG. 10: FT-IR spectra of untreated (solid), treated with DHA for 2 hours (dotted), for 4 hours (dotdash), and for 6 hours (longdash) at 60° C. in the range of 650-1000 cm.sup.−1.

[0033] FIG. 11: FT-IR spectrum of untreated (solid), treated with ECOC for 2 hours (dotted), for 4 hours (dotdash), and for 6 hours (longdash) at 60° C. in the range of 1100-1700 cm.sup.−1.

[0034] FIG. 12: FT-IR spectra of unreacted and reacted ECOC obtained from pre-treatment at various reaction conditions.

[0035] FIG. 13: The boiling point distribution of liquid oil obtained from microwave pyrolysis of E-waste plastics.

[0036] FIG. 14: FT-IR spectra of untreated (solid) and reacted (longdash) DHA obtained from DHA-assisted gas purification from 1600-600 cm.sup.−1.

[0037] FIG. 15: FT-IR spectra of unreacted (solid) and reacted (longdash) DHA in the range of 1600-900 cm.sup.−1.

[0038] FIG. 16: FT-IR spectrum of regenerated DHA.

[0039] FIG. 17: FT-IR spectrum of fresh DHA (Millipore Sigma, 2021 [36]).

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0040] Before the present invention is further described, it is to be understood that the invention is not limited to the particular embodiments described below, as variations of these embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments; and is not intended to be limiting. Instead, the scope of the present invention will be established by the appended claims.

[0041] In order to provide a clear and consistent understanding of the terms used in the present specification, a number of definitions are provided below. Moreover, unless defined otherwise, all technical and scientific terms as used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure pertains.

[0042] Use of the word “a” or “an” when used in conjunction with the term “comprising” in the claims and/or the specification may mean “one”, but it is also consistent with the meaning of “one or more”, “at least one”, and “one or more than one”. Similarly, the word “another” may mean at least a second or more.

[0043] As used in this specification and claim(s), the words “comprising” (and any form of comprising, such as “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “include” and “includes”) or “containing” (and any form of containing, such as “contain” and “contains”), are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

[0044] As used herein when referring to numerical values or percentages, the term “about” includes variations due to the methods used to determine the values or percentages, statistical variance and human error. Moreover, each numerical parameter in this application should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0045] As used herein, the term “dehalogenation agent” (DHA) refers to a chemical agent suitable for removing halogens and/or halogen-containing compounds from a material. In embodiments of the invention, the dehalogenation agent comprises an organophosphorus compound. In the present disclosure, term “emulsion-containing organophosphoric compound” (ECOC) is also used to designate the dehalogenation agent.

[0046] As used herein, the term “microwave-pyrolysis” refers to a pyrolysis process using a microwave heating technique.

[0047] As used herein, the term “microwave absorber” refers to material that absorbs microwaves and becomes heated. Such material is used in the microwave-pyrolysis and transfers its heat to the plastic material, thus assisting in the melting of the plastic material. Accordingly, a microwave absorber is used when the raw contaminated solid material contains plastic. Use of a microwave absorber may not be necessary when the raw material itself is a microwave absorber. The microwave absorber used is a carbon-based material such as for example SiC or carbon itself.

[0048] As used herein, the term “contaminated solid material” refers to the raw material used in the invention. The material may consist of any solid material that is contaminated and contains chemicals of concern (CoC) as defined herein below. Such solid materials include plastic materials and electronic waste plastic materials as defined herein below.

[0049] As used herein, the term “electronic waste (E-waste) plastic material” or “E-waste plastics” refers to the raw material used in this invention. The material consists of waste from various electronic equipment and contains chemicals of concern as defined herein above.

[0050] As used herein, the term “gas emission” refers to a gas stream emitted during the process of the invention. In particular, the gas emitted during the microwave-pyrolysis. The gas emission also refers to a gas emitted during any other process such as for example the combustion of E-waste, organic waste, oil or coal. It is to be understood that the gas purification treatment according to the invention may be applied to gases emitted during other processes.

[0051] As used herein, the term “chemicals of concern” (CoC) refers to chemicals present in the raw material used in the process of the invention. It is generally not desirable to have such chemicals present in solid materials discarded in the nature. Such chemicals are generally harmful to the nature or the health of humans. As indicated herein above, chemicals of concern comprise for example: acidic gases including halogenated gases such as HCl, HBr, and HF; volatile organic compounds (VOCs) including propylene, 1,3-butadiene, chloromethane, bromomethane, chloroethane, and vinyl chloride; and sulfur-containing compounds including sulfur oxides (SOx).

[0052] As used herein, the term “regeneration agent” (RGA) refers to a chemical used in the process of the invention to retrieve the dehalogenation agent (DHA) after use. The regeneration agent comprises a proton donor such as an acid. The acid may be inorganic (HCl, H.sub.2SO.sub.4) or organic.

[0053] The inventors have designed and performed a process for recycling contaminated solid materials including plastic materials such as electronic waste (E-waste) plastic materials. More specifically, the invention relates to such a process that uses a heating process including but not limited to microwave-pyrolysis. The process also uses a dehalogenation agent (DHA). The process according to the invention yields a solid phase, an oil phase, and a gas phase. The gas phase is further subjected to a purification treatment. The gas purification treatment according to the invention may be adapted for the purification of gases emitted from other processes.

[0054] The present invention is illustrated in further details in the Experiment Work section below. The section includes non-limiting examples.

[0055] To tackle the E-waste plastic recycling problems as discussed herein above, the inventors have developed an environmental-friendly and energy-sufficient recycling approach consisting of a pre-treatment with an effective dehalogenation agent (DHA), a microwave-assisted pyrolysis, a gas purification with DHA, and a regeneration process. The end products obtained from this developed process include: the purified gas that meet the environmental regulation, the valuable monomers-containing oil phase, and the precious metals-containing solid phase. The schematic diagram of this proposed recycling solution for contaminated E-waste plastics is depicted in FIG. 1.

Example 1—Pre-Treatment

[0056] Due to the presence of debris on the raw feedstock, the feedstock initially underwent washing by water (if needed) and then dried, and then cut into pieces having a dimension of about 5 about. DHA solution was prepared by mixing an organophosphorus (OP) compound and distilled water. The DHA solution is also referred to herein as emulsion-containing organophosphoric compound (ECOC). In the experiments conducted, di-(2-ethylhexyl) phosphoric acid was used as OP. The OP dosage is between about 0.1 to 30 vol. %, preferably between about 1 to 10 vol. %, most preferably between about 1 to 5 vol. %. To evaluate the performance of DHA in removing chemical of concern (CoC) from E-waste plastics, another pre-treatment solution containing toluene and OP was prepared as the reference. This reference pre-treatment solution is referred to herein as toluene-ECOC. Indeed, it is suggested in the prior art that toluene is a common extracting agent used in the treatment of contaminated E-waste plastics (Evangelopoulos et al., 2019 [18]; Mnim et al., 2003 [19]; Schlummer et al., 2005 [20]).

[0057] The flow chart for the experimental procedure used in the pre-treatment step is illustrated in FIG. 2. For a typical pre-treatment test, feedstock was mixed with pre-treatment solutions (ECOC or toluene-DHA) under constant stirring at 25° C. or 60° C. for a certain time, for example 2, 4, and 6 hours. At the end of the experiment, the solid and liquid fraction were separated. The liquid fraction, referred to herein as reacted ECOC, which was collected and stored for further analyses. The solid fraction was subjected to washing to remove any traces of ECOC, followed by drying.

Example 2—Microwave-Pyrolysis and Gas Purification

[0058] The flow chart for the experimental procedure used in the microwave pyrolysis and the gas purification is illustrated in FIG. 3 Erreur! Source du renvoi introuvable. This is performed after on the pre-treated feedstock obtained from the pre-treatment. The microwave pyrolysis and subsequent gas purification were also performed on the untreated feedstock as reference.

[0059] Prior to the experiment, an inert gas such as nitrogen gas was purged into the reactor to remove any remaining oxygen inside the reactor thereby creating an environment which is substantially oxygen-free.

[0060] For a typical run, the feedstock and SiC were added into the reactor. A microwave with a maximum power of and frequency of 2.45 GHz was used for the pyrolysis experiments. The pyrolytic products were then passed through a series of condensers and the liquid oil was condensed and collected. The non-condensable gases also referred to herein as untreated gas were passed through a column containing ECOC to remove toxic substances including halogenated gases (HBr, HCl, and HF), VOCs and SOx. The duration of the microwave pyrolysis depends on the amount of material loaded. The duration may be about 5 minutes.

Example 3—Regeneration

[0061] The regeneration process for the reacted DHA obtained from the pre-treatment and also from the gas purification was carried out using a regeneration agent (RGA) which a proton donor such as an acid. The amount of RGA used was chosen to be equivalent to the amount of the DHA such as to ensure regeneration of a maximum amount of DHA. The RGA dosage is between about 0.1 to 30 vol. %, preferably between about 1 to 10 vol. %, most preferably between about 1 to 5 vol. %; and the duration of the regeneration process is about 1 to 30 minutes.

[0062] A known amount of the RGA was added to the reacted ECOC after treatment process. The mixture was then exposed to stirring to ensure the complete separation of the DHA from the contaminants. Once the exchange reaction was completed, separating the DHA is easily performed due to its immiscibility with water as can be seen in FIG. 4. The regenerated agent was then separated from the liquid and sent for analyzed.

Analysis

[0063] A series of analytical techniques were applied to fully characterized the main products and by-products at each stage of the process according to the invention. Table 1 below summarizes the analytical techniques applied for the characterizations.

TABLE-US-00001 TABLE 1 Summary of the analytical techniques used at each step. Products and by-products Analytical techniques Raw feedstock NAA; SEM-EDX; FT-IR Pre-treatment Pre-treated feedstock SEM-EDX; FT-IR Reacted DHA FT-IR Microwave-pyrolysis Oil phase GC-MS; TGA Untreated gas phase FT-IR; Acidic gases; GC-MS (VOCs) Gas purification Clean gas FT-IR; Acidic gases; GC-MS (VOCs) Reacted DHA FT-IR Regeneration Regenerated DHA FT-IR

Feedstock—NAA Analysis

[0064] The elemental composition of the untreated feedstock or raw feedstock identified by neutron activation analysis (NAA) is presented in Table 2 below Table 2. As can be seen, Erreur! Source du renvoi introuvable. a high content of silicon was observed in the feedstock, which could be due to the presence of glass fiber substrates. It can also be seen that a high concentration of bromine in the feedstock, this might be attributed to the presence of BFRs in the E-waste. This feedstock also shows a high content of Na, Al, S, Cl, Fe, and Zn. The presence of glass fibers could cause the high concentration of Al and Fe since the preparation of glass fibers requires the addition of Al.sub.2O.sub.3 and SiO.sub.2. In addition, some trace elements were identified in the feedstock including F, Mg, K, Ca, Sc, Ti, V, Cr, Mn, Co, Cu, As, Se, Rb, Zr, Mo, Ag, Cd, In, Sn, Sb, I, Cs, Ba, La, Au, and Hg. Among these elements, the presence of elements such as Ca, Mg, and Ba could be attributed to the fiber glass present in the feedstock (Gao et al., 2021 [21]). A low concentration of Sb was also detected in the feedstock. Indeed, this element is sometimes used as additive in the plastic matrix to enhance the effectiveness of flame retardants (Zhan et al., 2020 [22]).

TABLE-US-00002 TABLE 2 The elemental composition of the raw feedstock used in this project as determined by NAA analysis. Con- Con- Con- centration centration centration Element (ppm) Element (ppm) Element (ppm) F <920 Fe 2,000 ± 300 Sn <50 Na 2,050 ± 80  Co  37 ± 2 Sb 10.2 ± 0.4  Mg   600 ± 200 Ni <100 I <0.6 Al 32,000 ± 1,000 Cu  898 ± 50 Cs <0.8 Si 27,000 ± 7,000 Zn 1,940 ± 80  Ba 100 Si <15,000 AS <0.6 La 7.1 ± 0.3 Cl 2,500 ± 100 Br 1,090 ± 80  Hf <1 K <770 Rb <20 W <0.7 Ca <140 Zr <470 Au <0.02 Se <2 Mo <3 Hg <0.5 Ti   900 ± 100 Ag <510 Mn 1.9 ± 0.2 V  10 ± 1 Cd <4 Cr  14 ± 5 In <0.07

Feedstock—SEM-EDX Analysis

[0065] For SEM-EDX analysis of raw feedstock, two prominent peaks corresponding to C and O were detected; see FIG. 5. A weak peak that can be ascribed to N was found, which could be due to the fact the feedstock contains ABS polymer and this is further supported by the FT-IR analysis of raw material described herein below. Additionally, strong peaks representing Br and Cl were observed in the feedstock, as evidenced by the results obtained from NAA analysis. Other strong peaks corresponding to Si and Na were identified, owing to the presence of glass fiber in the feedstock. Except for these strong peaks, the peaks that can be ascribed to F, Co, Mg, and Pb were also observed.

Feedstock—FT-IR Analysis

[0066] FT-IR analysis of the raw feedstock was performed, the resulting spectrum is shown in FIG. 6. The peaks at 3693, 3647, and 3618 cm.sup.−1 could be related to the O—H stretching. It was also found that the peaks at 2935 cm.sup.−1, 2920 cm.sup.−1, and 2851 cm.sup.−1 were identified in the feedstock, which could be due to the aliphatic C—H. A peak that is attributed to the presence of C≡N bond can be observed at 2237 cm.sup.−1, suggesting the presence of ABS polymer in the feedstock (Truc et al., 2017 [23]; Zhang et al., 2012 [24]). Besides, it was found that a peak corresponding to C═O stretching was observed at 1692 cm.sup.−1. A strong peak at 1599 cm.sup.−1 can be ascribed to the aromatic C═C vibration and a peak representing was found at 966 cm.sup.−1. Together, these results could imply the presence of HIPS polymer in the feedstock (Truc et al., 2017 [23]). The peaks at 1467 cm.sup.−1 and 1377 cm.sup.−1 representing methylene group and methyl group, respectively, which are reported to be the characteristics bonds of PP (Zhang et al., 2012 [25]; Wagner et al., 2020 [26]). A strong peak was identified at 1303 cm.sup.−1 and this could be ascribed to the C—F stretching (Limcharoen et al., 2013 [27]). Another peak at 1182 cm.sup.−1 corresponding to C—O of esters can be identified in the feedstock, which implies the feedstock might contain PC (Annamalai et al., 2020 [28]). The peaks at 1080 cm.sup.−1 and 667 cm.sup.−1 could be ascribed to the presence of BFR in the feedstock (Grigorescu et al., 2020 [29]). A strong peak of epoxy group was found at 829 cm.sup.−1 in the feedstock (Shen et al., 2018 [30]). Several peaks at 686 cm.sup.−1 and 752 cm.sup.−1 can be due to the presence of Pb—O—Pb and C—Cl bond in the feedstock, respectively.

Pre-Treatment—SEM-EDX Analysis

[0067] The SEM images of pre-treated feedstock obtained at different conditions are shown in FIG. 7. The presence of a relatively lower chemical contrast in the pre-treated feedstock could indicate the removal of higher atomic number contaminants in the plastic matrix, such as Pb, Cd, Hg, Br, and Cl.

[0068] FIG. 8 shows a reduction in the peak areas for all CoCs including F, Co, Br, Pb, and CO in the pre-treated feedstock obtained from pre-treatment using DHA solution (ECOC) at 25 or 60° C. On the contrary, no significant difference was found in the peak area of F, Br, and Pb of the pre-treated feedstock obtained from pre-treatment using toluene-DHA, and only a decrease in the peak area of Cl was found. Thus, it can be inferred that the removal efficiency of CoCs (i.e., F, Co, Br, Pb, and Cl) obtained from pre-treatment using ECOC was higher than that obtained from pre-treatment using toluene-DHA.

[0069] As illustrated in Table 3 below, the effect of reaction temperature on the removal efficiency of Co, F, Pb, and Br was insignificant. In contrast, the removal efficiency of Cl was proportional to the reaction temperature.

TABLE-US-00003 TABLE 3 Effect of reaction temperature on the removal efficiency of Co, F, Pb, and Br Temperature Br Cl F Co Pb 25° C. 77 72 43 32 72 60° C. 77 95 42 31 75

[0070] Clearly, as shown in Table 4 below, the pre-treatment removal efficiencies of Br, Cl, F, and Pb obtained from pre-treatment using DHA were higher compared to those obtained from pre-treatment using toluene-DHA. However, it was observed that the pre-treatment using toluene-DHA led to a higher removal efficiency of Co than that obtained using DHA at 25° C. but lower than that obtained using DHA at 60° C.

TABLE-US-00004 TABLE 4 Removal Efficiency of various chemicals of concern for different pre-treatment conditions. Removal Efficiency (%) Element DHA, 25° C. DHA, 60° C. Toluene-DHA Br 73 74 0 Cl 94 93 71 F 43 42 28 Co 9 31 15 Pb 76 68 9

Pre-Treatment—FT-IR Analysis

[0071] The FT-IR spectra of untreated feedstock and pre-treated feedstock obtained at 25° C. for 6 hours and 60° C. for 6 hours in the range of 650-1000 cm.sup.−1 are depicted in FIG. 9.

[0072] The intensity of the peak at 667 cm.sup.−1 representing C—Br of feedstock reduced after pre-treatment using DHA. A peak at 957 cm.sup.−1 was observed in the untreated feedstock and pre-treated feedstock, which could be related to the methylic C—Br stretching. Together with the reduced intensity of C—Br at 957 cm.sup.−1, it can be stated that the DHA-assisted pre-treatment is helpful for removing Br from the contaminated E-waste plastics. This is supported by the SEM-EDX analysis where the Br removal obtained at DHA-assisted pre-treatment at 25° C. and 60° C. was 73% and 74%, respectively (Table 4). Another peak at 686 cm.sup.−1 was detected in the untreated feedstock, which could be ascribed to the presence of Pb—O—Pb in the raw material. After DHA-assisted pre-treatment, it was found that the intensity of Pb—O—Pb bond reduced. Again, as indicated in Table 4, the Pb removal efficiency achieved by DHA-based pre-treatment was 68-76%. In addition, the peak corresponding to C—Cl bond was identified at 752 cm.sup.−1, and its intensity was found to reduce after pre-treatment, which is consistent with the results obtained from SEM-EDX analysis. The peak of epoxy group was found at 829 cm.sup.−1 in the untreated feedstock was stronger than that identified in the pre-treated feedstock. This lower intensity of epoxide group after pre-treatment could be due to the ring opening of epoxide in the acidic aqueous solution since the agent used is an acid. It is well known that epoxy resin is used to provide the protection for the electrical components against dust, moisture and short circuits.

[0073] The effect of reaction time on the CoC removal efficiency obtained from pre-treatment using DHA was investigated at 60° C. for 2, 4, and 6 hours. As shown in FIG. 10, no significant difference was observed between the spectrum of pre-treated feedstock obtained at 60° C. for 2 hours and untreated feedstock; however, a significant difference was found in the FT-IR spectrum of pre-treated feedstock when extending the processing time till 4 hours and 6 hours. The peak identified at 957 cm.sup.−1 can be ascribed to the C—Br stretching, and its intensity was found to be reduced after pre-treatment, especially at 4 hours and 6 hours. A stronger peak of epoxy group was found at 829 cm.sup.−1 in the untreated feedstock when compared with that of pre-treated feedstock obtained at 4 hours and 6 hours, which could be related to the ring-opening of epoxide in the pre-treatment. A similar observance was observed in the intensity of the C—Cl at 752 cm.sup.−1 and Pb—O—Pb at 686 cm.sup.−1.

[0074] The FT-IR spectra of the untreated and pre-treated feedstock obtained at 60° C. for 2 hours, 4 hours, and 6 hours in the range of 1100-1700 cm.sup.−1 are presented in FIG. 11. As shown in FIG. 12(a), a weaker peak at 1303 cm.sup.−1 representing C—F stretching was found in the pre-treated feedstock obtained at 4 hours and 6 hours compared to that in the untreated feedstock, implying the F was removed during the pre-treatment. This can be supported by a F removal efficiency of 42% was obtained at 60° C. for 6 hours (Table 4).

Pre-Treatment—Reacted DHA

[0075] FT-IR spectra of unreacted DHA and reacted DHA are presented in FIG. 12. No big difference can be observed in the FT-IR spectra of various reacted DHAs. A peak corresponding to C—F bond at 1040 cm.sup.−1 was only found in the reacted DHA, indicating the occurrence of the reaction between DHA and F-containing compounds during the pre-treatment. It was found that a peak at 880 cm.sup.−1 was absent in the unreacted DHA, which can be ascribed to C—Br bond. This phenomenon could suggest the reaction between DHA and Br-containing compounds during the pre-treatment, thereby reducing the Br concentration in the feedstock (Table 4). The peak representing C—O bond at 1084 cm.sup.−1 was absent in the unreacted DHA. In addition, a strong peak representing O—H stretching was observed at 1637 cm.sup.−1, which has been reported to be a main characteristic peak of DHA (de Silva et al., 2019 [31]). No significant difference was found in this peak before and after DHA-assisted pre-treatment, which may imply the high stability of DHA.

[0076] According to the FT-IR and SEM-EDX analyses of the pre-treated feedstock, it can be observed that DHA pre-treatment showed a positive role in removing Br, Cl, F, Co, and Pb from the contaminated E-waste plastics. In addition, based on the results obtained from the effect of temperature on the CoC removal efficiency obtained from DHA pre-treatment, this pre-treatment performed at room temperature led to a similar pre-treatment efficiency with that performed at higher temperatures (i.e., 60° C.). From the FT-IR analysis of reacted DHA, the high stability of DHA during the pre-treatment can be observed.

Microwave-Pyrolysis—GC-MS

[0077] The organic compounds in the pyrolysis oil were analyzed by GC-MS equipped with a HP-5MS capillary column. The main components of pyrolysis oil (with a relative peak area >1%) are summarized in Table 5 below. The components are classified in the table based on the structure characteristics (i.e., phenols, aromatic hydrocarbons excluding phenols, N-containing compounds, and others including compounds difficult to classify). It should be noted that only volatile compounds having a boiling point lower than 300° C. can be detected by the GC-MS. In general, a number of organic compounds can be detected in the pyrolysis oil from E-waste plastics, and some compounds can be utilized to produce other chemicals after separation. The results showed that no brominated compound was identified in the pyrolysis oil obtained. This can be explained as follows: the higher temperature was achieved in the microwave pyrolysis, leading to the decomposition of the brominated compounds such as 2-bromophenol and phenol 2,4-dibromo- which could be decomposed into small molecules such as bromomethane. The absence of the bromine-containing compounds ensures the low toxicity of the oil products.

TABLE-US-00005 TABLE 5 A summary of the main chemical compounds in the oil phase obtained from microwave pyrolysis of BFR-containing E-waste plastics. Area RT Percentage (min) (%) Compound Formula Aromatic hydrocarbons  2.96 2.05 o-Xylene C.sub.8H.sub.10  3.33 2.49 Styrene C.sub.8H.sub.8  4.16 1.09 Benzene, 1,2,3-trimethyl- C.sub.9H.sub.12 16.33 1.31 Benz[a]anthracene, 7-methyl- C.sub.19H.sub.14 22.98 1.63 5H-Tribenzo[a,f,k]trindene, 10,15- C.sub.27H.sub.18 dihydro- Phenols  4.46 12.13 Phenol C.sub.6H.sub.6O  5.47 11.63 Phenol, 2-methyl- C.sub.7H.sub.8O  5.90 2.09 p-Cresol C.sub.7H.sub.8O  6.20 14.22 Phenol, 2,6-dimethyl- C.sub.8H.sub.10O  6.92 12.65 Phenol, 2,4-dimethyl- C.sub.8H.sub.10O  7.18 2.30 Phenol, 3,5-dimethyl- C.sub.8H.sub.10O N-containing compounds 18.77 2.23 Pyrrole-2-carboxaldehyde, 1-[1-(1- C.sub.17H.sub.23NO adamantyl)ethyl]- 22.89 4.23 Purin-2,6-dione, 1,3-dimethyl-8- C.sub.17H.sub.18N.sub.4O.sub.4 [2-[3,4-dimethoxyphenyl]ethenyl]- Others 16.72 1.37 9,10-Anthracenedione, 1,2,6- C.sub.14H.sub.8O.sub.5 trihydroxy- 17.67 1.49 Benzoic acid, 2-(4-methylphenoxy)- C.sub.14H.sub.12O.sub.3 18.08 2.72 (3-Methoxyphenyl) methanol, 2- C.sub.13H.sub.20O methylbutyl ether 18.42 2.19 4,4′-Dimethoxybenzophenone C.sub.15H.sub.14O.sub.3 20.10 2.57 Triphenyl phosphate C.sub.18H.sub.15O.sub.4P

Microwave Pyrolysis—TGA

[0078] TGA analysis of oil obtained from microwave-pyrolysis of contaminated E-waste plastics was conducted to estimate its boiling point distribution. A simulated boiling point graph of the oil is shown in FIG. 13 and six distinct boiling point ranges including: 0-150° C., 150-200° C., 200-250° C., 250-300° C., 300-350° C., and ≥350° C. were identified.

[0079] With microwave pyrolysis, the fraction with a boiling point below 150° C. (40.36%), 150-200° C. (23.32%), and above 350° C. (16.24%), represented as the main components identified in the liquid oil from E-waste plastics. In a comparison, Ye et al. (2018) [33] performed the pyrolysis of waste printed circuit board using conventional heating, and a higher fraction of heavy oil (32.30%) with a boiling point >350° C. was observed. FIG. 13 shows the two fractions of oil was 63.68% and 20.08%, which indicates the high value of the E-waste plastics-derived liquid oil obtained using microwave heating. In another previous study, the oil fraction with a boiling point lower than 200° C. obtained from conventional pyrolysis with the use of Al.sub.2O.sub.3 was significantly lower than that obtained by microwave pyrolysis without a catalyst (Wang et al., 2015 [32]). Thus, the effectiveness of microwave heating in terms of producing light oil fraction from E-waste plastics can be verified.

Gas Purification

[0080] As indicated herein above, the untreated gas phase obtained from the microwave-pyrolysis of contaminated E-waste plastics was purified using DHA to remove or eliminate halogenated gases (e.g., HCl, HBr, and HF), VOCs, sulfur-containing compounds, and others.

Acidic Gases—Analyses

[0081] The removal efficiency of HCl, HBr, and HF obtained from DHA-assisted gas purification was measured using NIOSH 7907 and 7906. The results are summarized in Table 6 below. Previous studies suggested that HBr is a common toxic gas generated from the thermal degradation of E-waste plastics ([8], [11], [26]). As indicated in Table 6 Erreur! Source du renvoi introuvable., the concentration of HBr before and after the gas purification was lower than the detection limit of 0.15 ppm, which is considerably lower than the emission limit of 2.4 ppm. One possible reason could be the majority of Br existed in the form of bromomethane rather than HBr, as evidenced by the VOCs analysis. The results also showed that the concentration of HCl decreased from 2.2 ppm to <0.36 ppm after the gas purification treatment, and significantly lower than the emission limit of 18 ppm. Additionally, a sharp reduction in the HF concentration from 18 ppm to 0.74 ppm was observed after gas purification.

TABLE-US-00006 TABLE 6 Concentration of HF, HCl, and HBr before and after gas purification. Gases Untreated gas (ppm) Treated gas (ppm) Limit (ppm) HF 18 0.74 2.4 HCl 2.2 <0.36 18 HBr <0.15 <0.15 2.4

VOCs—Analyses

[0082] The concentration of VOCs before and after gas purification was determined by EPA TO-15 and the results are shown in Table 7 below. As can be seen, the concentration of propylene decreased from 1,030,000 ppb to 4,240 ppb with a removal efficiency of 99.59%. Additionally, 1,3-butadiene which is one of the toxic substances and is a probable carcinogen in humans, had its concentration reduced dramatically from 255,000 ppb to 10,900 ppb with a removal efficiency of 95.73%. The chlorinated gases including CH.sub.3Cl, C.sub.2H.sub.5Cl, and C.sub.2H.sub.3Cl were almost removed in the gas purification stage. In addition, a removal efficiency of 98.25% was observed for CH.sub.3Br where the concentration reduced from 10,800 ppb to 189 ppb. This result could indicate that the Br from the gas phase obtained from microwave pyrolysis is likely to exist in the form of CH.sub.3Br rather than HBr, which could be used to explain a very low concentration of HBr in the untreated gas (<0.15 ppm), as shown in Table 6.

TABLE-US-00007 TABLE 7 The removal efficiency of selected VOCs obtained from DHA-assisted gas purification. Untreated Treated Removal efficiency VOCs gas (ppb) gas (ppb) (%) Propylene 1,030,000 4,240 99.59 1,3-Butadiene 255,000 10,900 95.73 Chloromethane 152,000 81 99.95 Bromomethane 10,800 189 98.25 Chloroethane 1,580 13 99.21 n-Hexane 890 500 43.82 Vinyl chloride 390 7.7 98.03

DHA—FT-IR Analysis

[0083] FT-IR analysis of unreacted and reacted DHA was performed, and the resulting spectra are presented in FIG. 14. The sharp peaks at 728 cm.sup.−1 and 695 cm.sup.−1 were observed in the reacted DHA, which could be attributed to the presence of C—Cl and C—Br, respectively; while these peaks were absent in the fresh or unreacted DHA. This result could suggest the reaction between DHA and Cl- and Br-containing compounds in the gas purification, thereby leading to a reduction in the concentration of CH.sub.3Br and CH.sub.3Cl (Table 7).

[0084] As can be seen in FIG. 15, the intensities of peaks centered at 1229 cm.sup.−1 and 1033 m.sup.−1 of unreacted and reacted DHA were similar. As suggested by Cortina et al. (1997, [34]) and Cheraghi et al. (2015, [35]), they are characteristic peaks of DHA, which are attributed to the presence of P═O stretching vibration at 1229 cm.sup.−1 and P—O—H or P—O—C stretching vibration at 1033 m.sup.−1. Therefore, the high stability of DHA during the gas purification is observed.

[0085] The regenerated DHA was characterized using FT-IR analysis, and compared with the FT-IR spectrum of fresh DHA. As can be seen in FIG. 16 and FIG. 17, the FT-IR spectrum of regenerated and fresh DHA was similar, indicating the effectiveness of the regeneration step.

[0086] As will be understood by a skilled person, the present invention provides an alternative and environmental-friendly recycling approach for contaminated E-waste plastics. The process according to the invention comprises a pre-treatment of the raw feedstock, a microwave-pyrolysis of the pre-treated feedstock, gas purification. The pretreatment and the gas purification comprise use of a dehalogenation agent which can be regenerated and re-used in the process. With the implementation of the present invention, emission of halogenated gases, VOCs and sulfur-containing compounds which are commonly observed in the thermal degradation of E-waste plastics can meet the environmental regulations.

[0087] The removal efficiency of chemicals of concern (CoC) obtained from DHA-assisted pre-treatment was found to be substantially higher than conventional approach (i.e., approaches using toluene). The pre-treatment using DHA resulted in higher removal efficiencies of Br, Cl, F, Co, and Pb. Indeed, the values obtained were respectively 73-74%, 93-94%, 42-43%, 9-31%, and 68-76% which are higher than those obtained using toluene-DHA (Br: 0%; Cl: 71%; F: 28%; Co: 15%; and Pb: 9%).

[0088] According to the invention, it is possible to conduct DHA pre-treatment at room temperature without negatively affecting the CoC removal efficiency.

[0089] The major fractions of oil product obtained from the microwave-pyrolysis of E-waste plastics according to the invention were classified into low boiling point oils such as gasoline (63.68%) and medium boiling point oils such as diesel (20.08%).

[0090] DHA-assisted gas purification reduced the amounts of HF and HCl, from 18 ppm to 0.74 ppm and from 2.2 ppm to <0.36 ppm, respectively; and the concentration of HBr was below 0.15 ppm. Accordingly, the gas purification according to the invention is effective in removing acidic gases including HF, HCl, and HBr.

[0091] Regarding VOCs removal efficiency, the DHA-assisted gas purification according to the invention led to removal efficiencies of 95.73%, 99.95%, 98.25%, 99.21%, and 98.03% for 1,3-butadiene, chloromethane, bromomethane, chloroethane, and vinyl chloride, respectively.

[0092] In embodiments of the invention, the microwave may be applied at a frequency range between about 915 MHz to about 2450 GHz. As will be understood by a skilled person, other heating techniques than microwave may be used in the process. Such heating techniques may be for example induction heating, ultrasound, electromagnetic waves at other frequencies than microwave frequencies, electric field, magnetic field, plasma, or combinations thereof.

[0093] The process according to the invention embodies a system for performing the process and may be readily scaled up and integrated in an industrial facility. As will be understood by a skilled person, such system and facility are within the scope of the present invention.

[0094] In embodiments of the invention, the process may be batch operated, semi-batch operated, continuous flow operated, or combinations thereof. Also, in embodiments of the invention, the process may be s small scale, medium scale, large scale, or combinations thereof.

[0095] The scope of the claims should not be limited by the preferred embodiments set forth in the examples; but should be given the broadest interpretation consistent with the description as a whole.

[0096] The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety.

REFERENCES

[0097] [1] Forti V, Balde C P, Kuehr R, Garam B. 2020. The global E-waste monitor 2020: quantities, flows and the circular economy potential. United Nations University/United Nations Institute for Training and Research, International Telecommunication Union, and International Solid Waste Association. [0098] [2] Das P, Gabriel J C P, Tay C Y, Lee J M. 2021. Value-added products from thermochemical treatments of contaminated e-waste plastics. Chemosphere. 269, 129409. [0099] [3] Damrongsiri S, Vassanadumrongdee S, Tanwattana P. 2016. Heavy metal contamination characteristic of soil in WEEE (waste electrical and electronic equipment) dismantling community: a case study of Bangkok, Thailand. Environmental Science and Pollution Research. 23, 17026-17034. [0100] [4] Debnath B, Chowdhury R, Ghosh S K. 2018. Sustainability of metal recovery from E-waste. Frontiers of Environmental Science & Engineering. 12, 2. [0101] [5] Kefeni K K, Okonkwo J O, Olukunle O I, Botha B M. 2011. Brominated flame retardants: sources, distribution, exposure, pathways, and toxicity. Environmental Reviews. 19, 238-253. [0102] [6] Olubanjo K, Osibanjo O, Chidi Ni. 2015. Evaluation of Pb and Cu contents of selected component parts of waste personal computers. Journal of Applied Sciences and Environmental Management. 19, 470-477. [0103] [7] Ortuño N, Moltó J, Conesa J A, Font R. 2014. Formation of brominated pollutants during the pyrolysis and combustion of tetrabromobisphenol A at different temperatures. Environmental Pollution. 191,31-37. [0104] [8] Wong M H, Wu S C, Deng W J, Yu X Z, Luo Q, Leung A O W, Wong C S C, Luksemburg W J, Wong A S. 2007. Export of toxic chemicals—a review of the case of uncontrolled electronic-waste recycling. Environmental Pollution. 149, 131-140. [0105] [9] Lilienthal H, van der Ven L T M, Piersma A H, Vos J G. 2009. Effects of the brominated flame retardant hexabromocyclododecane (HBCD) on dopamine-dependent behavior and brainstem auditory evoked potentials in a one-generation reproduction study in Wistar rats. Toxicology Letters. 185, 63-72. [0106] [10] Mohammed M I, Mohan M, Das A, Johnson M D, Singh P B, McLean D, Gibson I. 2017. A low carbon footprint approach to the reconstitution of plastics into 3D-printer filament for enhanced waste reduction. The International Conference on Design and Technology. 234-241. [0107] [11] Arvanitoyannis I S. 2013. Waste management for polymers in food packaging industries. In: Plastic films in food packaging. William Andrew Publishing, Oxford. [0108] [12] Stewart E, Lemieux P. 2003. Emission from the incineration of electronics industry waste. IEEE International Symposium on Electronics and the Environment. 271-275. [0109] [13] Yin J, Li G, He W, Huang J, Xu M. 2011. Hydrothermal decomposition of brominated epoxy resin in waste printed circuit boards. Journal of Analytical and Applied Pyrolysis. 92, 131-136. [0110] [14] Zhao X Y, Xia Y H, Zhan L, Xie B, Gao B, Wang J L. 2019. Hydrothermal treatment of e-waste plastics for tertiary recycling: product slate and decomposition mechanisms. ACS Sustainable Chemistry & Engineering. 7, 1464-1473. [0111] [15] Zhang T H, Mao X, Qu J S, Liu Y, Siyal A A, Ao W Y, Fu J, Dai J J, Jiang Z H, Deng Z Y, Song Y M, Wang D Y, Polina C. 2021. Microwave-assisted catalytic pyrolysis of waste printed circuit boards, and migration and distribution of bromine. Journal of Hazardous Materials. 402, 123749. [0112] [16] Liu M, Zhuo J K, Xiong S J, Yao Q. 2014. Catalytic degradation of high-density polyethylene over a clay catalyst compared with other catalysts. Energy Fuels, 28, 6038-6045. [0113] [17] Hall W J, Miskolczi N, Onwudili J, Williams P T. 2008. Thermal processing of toxic flame-retarded polymer using a waste fluidized catalytic cracker (FCC) catalyst. Energy Fuels. 22, 1691-1697. [0114] [18] Evangelopoulos P, Arato S, Persson H, Kantarelis E, Yang W. 2019. Reduction of brominated flame retardants (BFRs) in plastics from waste electrical and electronic equipment (WEEE) by solvent extraction and the influence on their thermal decomposition. Waste Management. 94, 165-171. [0115] [19] Mnim A A, Wolf M, van Eldik R. 2003. Extraction of brominated flame retardants from polymeric waste material using different solvents and supercritical carbon dioxide. Analytica Chimica Acta. 491, 111-123. [0116] [20] Schlummer M, Brandl F, Maurer A, van Eldik R. 2005. Analysis of flame retardant additives in polymer fractions of waste of electric and electronic equipment (WEEE) by means of HPLC-UV/MS and GPC-HPLC-UV. Journal of Chromatography A. 1064, 39-51. [0117] [21] Gao R T, Liu B Y, Zhan L, Guo J, Zhang J, Xu Z M. 2021. Catalytic effect and mechanism of coexisting copper on conversion of organics during pyrolysis of waste printed circuit boards. Journal of Hazardous Materials. 403, 123465. [0118] [22] Zhan L, Zhao X Y, Ahmad Z, Xu Z M. 2020. Leaching behavior of Sb and Br from E-waste flame retardant plastics. Chemosphere. 245, 125684. [0119] [23] Truc N T T, Lee B K. 2017. 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. 329, 84-91. [0120] [24] Zhang C C, Zhang F S. 2012. Removal of brominated flame retardant from electrical and electronic waste plastic by solvothermal technique. Journal of Hazardous Materials. 221-222, 193-198. [0121] [25] Zhang J, Zhang L, Suttonn D, Wang X G, Lin T. 2012. Needleless melt-electrospinning of polypropylene nanofibers. Journal of Nanomaterials. 2012, 382639. [0122] [26] Wagner F, Peeters J R, Ramon H, Keyzer J D, Duflou J R, Dewulf W. Quality assessment of mixed plastic flakes from waste electrical and electronic equipment (WEEE) by spectroscopic techniques. Resources, Conversion and Recycling. 158, 104801. [0123] [27] Limcharoen A, Limsuwan P, Pakpum C, Siangchaew K. 2013. Chacterization of C—F polymer film formation on the air-bearing surface etched sidewall of fluorine-based plasma interaction with Al.sub.2O.sub.3—TiC substrate. Journal of Nanomaterials. 2013, 851489. [0124] [28] Annamalai M, Gurumurthy K. 2020. Characterization of end-of-life mobile phone printed circuit boards for its elemental composition and beneficiation analysis. Journal of the Air & Waste Management Association. 315-327. [0125] [29] Grigorescu R M, Ghioca P, lancu L etc. 2020. Development of thermoplastic composites based on recycled polypropylene and waste printed circuit boards. Waste Management. 118, 391-401. [0126] [30] Shen Y F, Chen X M, Ge X L, Chen M D. 2018. Chemical pyrolysis of E-waste plastics: char characterization. Journal of Environmental Management. 214, 94-103. [0127] [31] de Silva F N, Bassaco M M, Bertuol D A, Tanabe E H. 2019. An eco-friendly approach for metals extraction using polymeric nanofibers modified with di-(2-ethylhexyl) phosphoric acid (DEHPA). Journal of Cleaner Production. 210, 786-794. [0128] [32] Wang Y, Sun S Y, Yang F, Li S Y, Wu J Q, Liu J Y, Zhong S, Zeng J J. 2015. The effects of activated Al2O3 n the recycling of light oil from the catalytic pyrolysis of waste printed circuit boards. Process Safety and Environmental Protection. 98, 276-284. [0129] [33] Ye Z W, Yang F, Qiu Y Q, Chen N W, Lin W X, Sun S Y. 2018. The dibrominated and lightweight oil generated from two stage pyrolysis of WPCBs by using compound chemical additives. Process Safety and Environmental Protection. 116, 654-662. [0130] [34] Cortina J L, Miralles N, Aguilar M. 1997. Solid-liquid extraction studies of divalent metals with impregnated resins containing mixtures of organophosphorous extractants. Reactive and Functional Polymers. 32, 221-229. [0131] [35] Cheraghi A, Ardakani M S, Alamdari E K, Fatmesari D H, Darvishih D, Sadrnezhaad S K. 2015. Thermodynamics of vanadium (V) solvent extraction by mixture of D2EHPA and TBP. International Journal of Mineral Processing. 138, 49-54. [0132] Millipore Sigma (2021). Bis(2-ethylhexyl) phosphate FTIR. https://www.sigmaaldrich.com/spectra/ftir/FTIR003572.PDF. Accessed at Apr. 21, 2021.