METHOD FOR OBTAINING GRAPHENE-TYPE MATERIALS FROM COKE AND THEIR USE AS RAW MATERIAL IN THE MANUFACTURE OF BIOSENSORS AND AS POLYMERIC ADDITIVES.

Abstract

Manufacturing methods for graphene-like materials using a planetary mill (mechanical milling) with a configuration different from those used commercially and aided by low-melting-point fatty acids are described. The resulting materials are successfully used as fillers for the formation of ABS polymer matrices with good toughness. Furthermore, the compounds obtained after the milling process are functionalized with metallic nanoparticles (Cu and Ag) and tested for glucose and hydrogen peroxide at different pH levels (7 and 12) and concentrations. Finally, this process can be considered sustainable for obtaining graphene-like materials because it uses very low-value raw materials (coke and fatty acids) to generate materials with characteristics similar to, and even better than, those obtained from higher-value raw materials.

Description

METHOD FOR OBTAINING GRAPHENE-TYPE MATERIALS FROM COKE AND THEIR USE AS RAW MATERIAL IN THE MANUFACTURE OF BIOSENSORS AND AS POLYMERIC ADDITIVES DESCRIPTION OBJECT OF THE INVENTION Mechanical treatment process to obtain graphene-like derivatives from various cokes and the use of the materials for the manufacture of electrochemical biosensors for measuring hydrogen peroxide and glucose and as fillers for the manufacture of graphene-like polymer composites with improved mechanical properties. BACKGROUND Thousands of articles are published annually describing the use of graphene derivatives as components of various devices or as nanoscale fillers in polymer composites with enhanced mechanical, electrical, or thermal properties. [1-5] Low-layer graphene materials (< 10) or multilayer stacked graphene nanoplatelets (> 10) are commonly prepared using graphite as a starting material through various delamination methods. One of the most widely used methods involves oxidizing graphite and delaminating the resulting graphite oxide (GtO) to generate single-layer graphene oxide (GO), followed by chemical or thermal reduction to reduced graphene oxide (rGO) [6-9]. However, these methods are not environmentally acceptable and often result in defects in the graphene materials, and yields are typically low.Most graphite oxidation methods are based on the procedure published by Hummers

[10] , which uses concentrated sulfuric acid (H2SO4) as the reaction medium, employing potassium permanganate and sodium nitrate (KMnO4NaNCh) as oxidants. During oxidation, potentially explosive toxic gases (NO2, N2O4, and chlorine oxides) are generated, making the procedure hazardous and not easily scalable

[11] . Another preparative procedure uses mechanical size reduction-exfoliation treatments of graphite using various types of mills to manufacture graphene derivatives, either by dry treatment or with the aid of exfoliation solvents. Several potentially economical and scalable milling treatments have been described that offer the possibility of producing graphene in large quantities [12-15].Dry or liquid grinding of graphite has been studied, finding that dry grinding in the presence of air or an oxygen atmosphere leads to the formation of functionalized materials with oxidized groups

[16] .Milling treatment has been used to functionalize the periphery of graphene sheets; for example, milling graphite in the presence of CO2 leads to the formation of carboxylated derivatives used in the development of organic solar cell cathodes with dyes

[17] , lithium-ion batteries

[18] , dye-sensitized solar cells (DSSCs)

[19] , supercapacitors

[20] , and as nanometric polymer fillers

[21] . Functionalization of graphene by introducing nitrogen or sulfur heteroatoms by milling graphite under an N2 atmosphere

[22] or in the presence of sulfur [23-24] has also been reported. Furthermore, milling in the presence of liquid media has been used advantageously to manufacture suspensions or exfoliated graphene powder after solvent removal.Among the first examples, the production of graphene by grinding graphite for 30 hours in a planetary mill using dimethylformamide as a solvent has been reported, yielding 32% by weight after centrifugation and solvent removal

[25] . Graphite has been exfoliated by treating it for 12 hours in aqueous suspensions containing polyoxoethylene naphthol ether as a delamination aid; this treatment generates suspensions with graphene contents of 0.5–1.2 mg mL⁻¹, which is separated by filtration and washing with ethanol (26). The preparation of 0.085 mg graphene / mL N-methylpyrrolidone suspensions has been demonstrated after 10 hours of grinding in the presence of this solvent

[27] . A 60-hour high-energy grinding procedure in the presence of 2-ethylhexanol or kerosene has also been reported, which, after solvent removal and 3 hours of heat treatment, yields graphene. At 600 °C, graphene with a low number of layers is obtained

[28] . In another procedure, aqueous solutions of ethanol are used to treat equal weights of graphite and trimethylcetryl ammonium chloride for 2 to 16 hours, and then the graphene products are isolated; in this method a ball mill is used and the products are used as materials for sensing phenols.

[29] Although the production of graphene from graphite has received considerable attention, very few reports have been published describing the use of other precursors as raw materials. Sierra et al.

[30] have obtained graphene-like materials via the thermal treatment of cokes, comparing them with those prepared from graphite. They have also described the synthesis of graphene-like materials through the oxidation-exfoliation-reduction of untreated pre-graphitic materials [31-32]. Recently, a similar oxidation-exfoliation-reduction treatment of coke needles for the production of graphene-like materials has been published

[33] . Although pre-graphitic cokes offer the advantage of their abundance and low cost, the methods used to transform them into graphene-like derivatives have the drawback of relying on a complex, highly polluting, and low-yield initial oxidative treatment.Therefore, it is desirable to have methods for preparing graphene-like materials capable of utilizing pre-graphitic cokes, without having to use the preparative methods reported in the literature. The object of this invention is to demonstrate that pre-graphitic cokes can be converted into graphene-like materials by a few hours of mechanical delamination treatment in the presence of fatty acid, using a planetary mill equipped with a grinding vessel in which a large, heavy grinding mass is employed instead of the commonly used spherical grinding media. When a fatty acid-pre-graphitic coke mixture with a weight ratio of 2:1 is subjected to two or more hours of the grinding treatment, graphene-like materials are obtained with a near-quantitative yield after the fatty acid is removed by dissolution with appropriate solvents. It is also demonstrated that the products can be converted into compounds decorated with copper or silver nanoparticles useful in the electrochemical sensing of hydrogen peroxide or glucose content in aqueous media.In turn, it is proven that delaminated materials are useful in the manufacture of ABS-nanofilled composite materials, increasing the mechanical properties of the polymeric composites. References 1. An Li, Cong Zhang and Yang-Fei Zhang. Thermal conductivity of Graphene-polymer composites: mechanisms, properties, and applications. 2017. 9; 437. 2. Rasheed Atif, Islam Shyha and Fawad Inam. Mechanical, thermal, and electrical properties of Graphene-epoxy nanocomposites - A review. Polymers. 2016. 8: 281. 3. Mrinal Bhattacharya. Polymer nanocomposites- A comparison between carbon nanotubes, Graphene, and clay nanofillers. Materials. 2016. 9: 262. 4. Xuqiang J¡, Yuanhong Xu, Wenling Zhang, Liang Cui, Jingquan Liu. Review of functionalization, structure and properties of Graphene / polymer composite fibers. Composites: Part A. 2016. 87: 29-45. 5. W. K. Chee, Η. N. Lim, N. M. Huang and I. Harrison. Nanocomposites of Graphene / polymers: a review. RSC. Adv. 2015. 5: 68014-68051. 6. Μ. T. H. Aunkor, I. M. Mahbubul, R. Saidur and H. S. C. Metselaar. The green reduction of Graphene oxide. RSC Adv. 2016. 6: 27807-27828. 7. Sajjad Shamaila, Ahmed Khan Leghari Sajjad, Anum Iqbal. Modifications in development of Graphene oxide synthetic routes. Chem. Eng. J. 2016. 294: 458-477 8. Rajesh Kumar Singh, Rajesh Kumar and Dinesh Pratap Singh. Graphene oxide: strategies for synthesis, reduction and frontier applications. RSC. Adv. 2016. 6: 64993-65011. 9. Sungjin Park, Rodney S. Ruoff. Synthesis and characterization of chemically modified graphenes. Current Opinión in Colloid & Interface Science. 2015. 20: 322-328. 10. Hummers WS, Offeman RE. Preparation of graphite oxide. J. Am. Chem. Soc. 1958. 80: ηοββηη / ηζηζ / κ / γίΛΐ 1339. 11. Botas C, Alvarez P, Blanco C, Santamaría R, Granda M, Gutiérrez MD, et al. Critical temperatures in the synthesis of Graphene-like materials by termal exfoliation-reduction of Graphene oxide. Carbón. 2013. 52: 476-485. 12. Sha Deng, Xiaodong Q¡, Yan-ling Zhu, Hong-ju Zhou, Feng Chen and Qiang Fu. A facile way to large-scale production of few-layered Graphene vía planetary ball mil. Chínese Journal of Polymer Science. 2016. 34;10: 1270-1280. 13. Min Y¡ and Zhigang Shen. A review on mechanical exfoliation for the scalable production of Graphene. J. Mater. Chem. A. 2015.3:11700-11715 14. Min Mao, Shuzhen Chen, Ping He, Hailin Zhang and Hongtao Liu. Facile and economical mass production of Graphene dispersions and flakes. J. Mater. Chem. A. 2014. 2: 41324135. 15. Weifeng Zhao, Ming Fang, Furong Wu, Hang Wu, Liwei Wang and Guohua Chen. Preparation of Graphene by exfoliation of graphite using wet ball milling. J. Mater. Chem. 2010. 20: 5817-5819. 16. T. S. Ong, H. Yang. Effect of atmosphere on the mechanical milling of natural graphite. Carbón. 2000. 38: 2077-2085. 17. Narayan Chandra Deb Nath, In-Yup Jeon, Myung Jong Ju, Sajid Ali Ansar!, Jong-Beom Baek, Jae-Joon Lee. Edge-carboxylated Graphene nanoplatelets as efficient electrode materials for electrochemical supercapacitors. Carbón. 2019. 142: 89-98. 18. Zhu H, et al. One-step preparation of Graphene nanosheets vía ball milling of graphite and the application in lithium-ion batteries. J. Mater. Sci. 2016. 51 (8): 3675-83 19. Do Hyung Kweon and Jong-Beom Baek. Edge-functionalized Graphene nanoplatelets as metal-free electrocatalysts for dye-sensitized solar cells. Adv. Mater. 2019. 31: 1804440. 20. Wang H, fu Q, Pan C. Green mass synthesis of Graphene oxide and its MnO2 composite for high performance supercapacitor. Electrochi. Acta. 2019. 312:11 -21. ηοββηη / ηζηζ / κ / γίΛΐ 21. Dul S, Pegoretti A, Fambri L. Effects of the nanofillers on physical properties of acrylonitrilebutadiene-styrene nanocomposites: comparison of Graphene nano-platelets and multiwall carbón nanotubes. Nanomaterials. 2018. 8(9):974. 22. In-Yup Jean, Hyun-Juang Choi, et al. Direct nitrogen fixation at the edges of Graphene nanoplatelets as efficient electrocatalysts for energy conversión. Sci. Rep. 2013. 3: 2260. 23. Aniello Vittore, María Rosaría Acocella, Gaetano Guerra. Graphite functionalization by ball milling with sulfur. SN Applied Sciences. 2019. 1:169. 24. In-Yup Jeon, et al. Edge-selectively sulfurized Graphene nanoplatelets as efficient metalfree electrocatalysts for oxygen reduction reaction: the electros spin effect. Adv. Mater. 2013. 25: 6138-6145 25. Weifeng Zhao, Furong Wu, Hang Wu and Guohua Chen. Preparation of coloidal dispersión of Graphene sheets in organic solvents by using ball milling. Journal of Materials. 2010: 528235. 26. Zhai W, Wu F, Wu H. Chen G. Preparation of coloidal dispersions of Graphene sheets in organic solvents by using ball milling. J. Nanomater. 2010. 2010. 27. Y¡ M, Shen Z. A review on mechanical exfoliation for the scalable production of Graphene. J. Mater. Chem. A. 2015. 3 (22): 11700-15. 28. Al-Sayed Al-Sherbini, Mona Bakr, Imán Ghoneim, Mohamed Saad. Exfoliation of Graphene sheets vía high energy wet milling of graphite in 2-ethylhexanol and kerosene. Journal of Advanced Research. 2017. 8; (3): 209-215 29. Xiaoyu L¡, Jian Shen, Can Wu and Kangbing Wu. Ball-mill-exfoliated Graphene: tunable electrochemistry and phenol sensing. Small. 2019. 1805567:1 -10 30. Uriel Sierra, Patricia Álvarez, Clara Blanco, Marcos Granda, Ricardo Santamaría, Rosa Menéndez. New alternatives to graphite for producing graphene materials. Carbón. 2015. noRRnn / nznz / R / YiAi 93:812-818. 31. Uriel Sierra, Patricia Álvarez, Clara Blanco, Marcos Granda, Ricardo Santamaría, Rosa Menéndez. Cokes of different origin as precursors of Graphene oxide. Fuel. 2016. 166: 400-403. 32. Salvador Fernández, Alfonso Mercado, Edgar Cuara, Claudia Yeverino-Miranda, Uriel Sierra. Asphalt as raw material of Graphene-like resources. Fuel. 2019. 24: 297-303. 33. Laura Burk, Matthias Gliem and Rolf Mülhaupt. Mechanochemical routes to functionalized Graphene nanofillers tuned for lightweight carbon / hydrocarbon composites. Macromol. Mater. Eng. 2019. 304 (2); 1800496: 1-22. 34. Patil A, Patel A, Purohit R. An overview of polymeric materials for automotive applications. Mtaer Today Proc. 2017. 4(2): 3807-15 35. Srivastava V. Advances in automotive polymer applications and recycling. Int. J. Innov. Res. Sci. Eng. Technol. 2013. 2(3): 744-6 36. Jyoti J, Basu S, Singh BP, Dhakate RS. Superior mechanical and electrical properties of multiwall carbón nanotube reinforced acrylonitrile butadiene styrene high performance composites. Compos. Part. B. Eng. 2015. 83: 58-65 37. Panwar V, Pal K. An optimal reduction technique for rGO / ABS composites having high-end Dynamic properties base don Cole-Cole plot. Degree of entanglement and C-factor. Compos. Part. B. Eng. 2017. 114: 46-57. 38. Huang G, et al. Realizing simultaneóos improvements in mechanical strength, fíame retardancy and smoke suppression of ABS nanocomposites from multifunctional Graphene. Compos. Part. B. Eng. 2019. 177: 107377 39. Jyoti J, Babal AS, Sharma S, Dhakate RS, Singh BP. Significant improvement in static and Dynamic mechanical properties of Graphene oxide-carbon nanotube acylonitrile butadiene styrene hybrid composites. J. Mater. Sci. 2018. 53 (4): 2520-36 40. Mohd Alauddin S, Isma ¡L I, Shafiq Zaili F, Farahanis llias n, Fadhilah Kamalul Aripin N. Electrical and mechanical properties of acrylo-nitrile butadiene styrene / Graphene platelet nanocomposite. Mater. Today. Proc. 2018. 5: S125-9 41. Triantou MI, Stathi Kl, Tarantili PA. Thermal, mechanical, and dielectric properties of injection molded Graphene nanocomposites basad on ABS / PC and ABS / PP blends. Polym. Compos. 2019. 40 (S2): E1662-72 42. Dul S, et al. Effect of Graphene nanoplatelets structure on the properties of acrylonitrilebutadiene-styrene composites. Polym. Compos. 2019. 40: E285-300 BRIEF DESCRIPTION OF THE FIGURES Figure 1. Side view drawing of the grinding system. It is evident that the separation between the grinding media and the treatment vessel is quite small, which reduces the impact on the treated material that would otherwise be trapped between the treatment medium and the vessel wall. Figure 2. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) images; the former show the height profile of the obtained sheets, indicating that the materials are single-layered or have a very low number of layers. The TEM images corroborate this observation, showing thin layers of exfoliated material, 2a) CkP, 2b) CkM, and 2c) CkH. Figure 3. % elongation at maximum load of ABS compounds with different weight contents of cokes. Figure 4. X-ray diffraction of the starting and exfoliated coke samples 1 and 4 hours, 4a) starting cokes, 4b) exfoliated cokes 1 h and 4c) exfoliated cokes 4 h. Figure 5. Thermogravimetry of the starting and exfoliated coke samples 1 and 4 hours, 5a) starting cokes, 5b) exfoliated cokes 1 h and 5c) exfoliated cokes 4 h. Figure 6. Cyclic voltammetry of the currents obtained at pH 7 at different concentrations of hydrogen peroxide using the compound CkP-Ag. Figure 7. Cyclic voltammetry of the currents obtained at pH 12 at different concentrations of hydrogen peroxide using the compound CkH-Ag. Figure 8. Cyclic voltammetry of the currents obtained at pH 12 at different glucose concentrations using the CkH-Cu compound. noRRnn / nznz / R / YiAi DETAILED DESCRIPTION OF THE INVENTION Exploring more effective alternatives for obtaining graphene-like materials from coke without oxidative treatments, we explored coke delamination by planetary milling using a milling vessel equipped with a single grinding media, replacing the multiple metal or ceramic spheres commonly used for this purpose. It is known that when milling with solid spheres, their free movement results in high-energy impacts (sphere-material-sphere; sphere-material-container wall) that primarily reduce the size of the treated material and only partially facilitate the sliding and separation of its constituent layers.In these systems, it is common to vary the size of the grinding media and the weight ratio between the media and the material being processed. It has been observed that an increase in the weight ratio of the grinding media leads to a greater reduction in the size of the ground material, primarily as a consequence of the increased number of impacts received by the material. Considering this, and seeking to achieve greater grinding efficiency, we studied increasing the weight of the grinding media without increasing the number of impacts between it and the material being processed. To this end, we explored the use of a heavy grinding media that would prevent or reduce the number of impacts received by the material being ground.With this, the commonly used spheres were replaced by a grinding media with dimensions similar to those of the treatment vessel. We demonstrate that this change modifies the movement of the grinding media, limiting its displacement to oscillating rotary motions that rub against the graphite surface without impacting it. This rotary sliding motion facilitates the interlaminar separation of the graphene sheets without excessively breaking them, a separation that becomes more effective when using a higher weight ratio of grinding media to sample. Figure 1 shows the design of the vessel and grinding media, indicating the dimensions of both and the fit of the latter to the grinding vessel. It is worth noting that the geometry of the lower part of the grinding media follows the curved geometry of the lower surface of the grinding vessel, reducing the gap between the two surfaces and ensuring that the material to be ground is trapped between them.Additionally, to increase the treatment's efficiency, the milling is carried out in the presence of a soft, solid organic material that acts as an exfoliation aid. This material lubricates the rotary motion of the mill over the coke materials, reducing the energy transferred to them, improving the separation of their layers through sliding motion, and minimizing the breakage of the graphene-like sheets that compose them. We have determined that solid fatty acids can be used as an exfoliating material in this treatment system. Fatty acids offer the advantages of their wide distribution and low cost, and they are easily dissolved in various organic solvents. As an additional benefit of the system, we found that the soft lubricant becomes interspersed between the material sheets as they separate, reducing the tendency of the graphene sheets to re-stack. In a proof-of-concept test of the system, three cokes donated by Industrial Minera México SA de CV (Nueva Rosita Plant, Coahuila) were processed. The materials were: petroleum coke (CkP), metallurgical coke (CkM), and high-temperature coke (CkH). It was found that the amount of coke to be ground and its weight ratio to the exfoliating fatty acids could be varied, as could the grinding time, which could range from one to several hours, and the mass weight. While it is possible to vary the fatty acid-to-coke weight ratio, using a 1:1 ratio requires a longer grinding time, whereas ratios greater than 2:1 do not lead to significant improvements in delamination efficiency. Therefore, although the weight ratio range can be from 1:1 to 10:1 or more, a 2:1 ratio has been determined to be adequate for achieving exfoliation of the materials.Regarding the grinding time, this can be modified from one to several hours. It was found that a grinding treatment of less than one hour does not yield consistent results (measurement of graphitic signal intensity by X-ray diffractometry and measurement of product surface area), and that the interval of 1 to 4 hours is sufficient to achieve delamination. The surface area measurements of the delaminated cokes (Sbet m2g-1) within this interval, shown in Table 1, indicate an increase in the surface area of ​​the cokes after treatment. This increase is particularly pronounced when comparing the one-hour and four-hour treatments, respectively, suggesting greater delamination of the cokes with longer grinding times, as well as a possible reduction in size. Table 1. Surface areas (Sbet m2g-1) of the starting cokes, exfoliated 1 and 4 h respectively. Sample Precursors Sbet m2g'1 1h 4h CkP 0.719 4.302 12.483 CkM 2.604 3.100 4.967 CkH 4.318 5.109 6.092 The images (Figure 2, 2a) starting cokes, 2b) exfoliated cokes 1 h and 2c) exfoliated cokes 4 h) obtained by atomic force microscopy (AFM) and transmission electron microscopy (TEM) show that the exfoliated materials are composed of one or very few sheets similar to those presented by graphene materials exfoliated by different methods, corroborating that the cokes generate graphene-like materials after the treatment described here. Regarding the weight of the mass used as a grinding medium, it has been determined that a heavier mass leads to better delamination of the cokes and that the use of lighter masses requires increasing the grinding time needed to obtain similar results to those achieved using a heavier mass. Given the various uses found for graphene derivatives obtained from graphite, the graphene-like materials obtained here were evaluated as manufacturing substrates for materials decorated with copper and silver nanoparticles for sensing molecules of biological importance (H2O2 and glucose) and as mechanical reinforcers of nanometric ABS filler compounds. To determine their potential use as sensing materials, copper-coke and silver-coke compounds were prepared with a 1:0.1 weight ratio by ascorbic acid reduction of aqueous suspensions of the cokes containing copper sulfate pentahydrate or silver nitrate, respectively. Typically, 100 mg of petroleum, metallurgical, or high-temperature coke were placed in 75 mL of distilled water containing the amount of salt necessary to produce 10 mg of copper or silver. The suspensions were treated for 10 minutes by immersing the ultrasonic tip of a sonotrode operated at 60% power. After this time, ascorbic acid was added at a molar ratio of 1:43 copper or silver salt to reducing agent, and sonication was continued for an additional 15 minutes. The suspensions were vacuum filtered, and the solid was washed repeatedly with distilled water and finally with acetone. The products were dried at 70 °C for 12 hours.Vitreous carbon electrodes were fabricated from the obtained materials by applying 5 pL of 5 mg / mL suspensions of 0.1 mg / mL PEDOT:PPS solution to their surface. Electrochemical measurements of hydrogen peroxide and glucose content were performed using these electrodes at pH 7 and 12 for hydrogen peroxide and at pH 12 for glucose determination. The results obtained from these measurements are presented in Table 2. In general, it can be observed that the coke-Ag compounds provide better hydrogen peroxide sensing responses than the coke-Cu compounds. However, it is important to note that the silver derivatives do not detect glucose (not shown in the Table), while the copper derivatives do, with CkH exhibiting the best sensitivity at 224 μA / cm² / mM. On the other hand, while coke-Cu products are not able to sense hydrogen peroxide at pH 7, coke-Ag derivatives show responses at this pH.It is also observed that at pH 12 the CkP can measure H2O2 contents both by reduction (169 pA / cm2mM at -650 mV) and by oxidation (207 pA / cm2mM at +850 mV). Table 2. Sensitivity in the detection of glucose and H2O2 at pH 7 and 12. Sample Measurement of: pH Sensitivity μA / cm2 mM (voltage) CkP-Cu H2O2 7 0 (-650 mV) 0 (+850 mV) H2O2 12 169 (-650 mV) 207 (+850 mV) Glucose 12 0 (-650 mV) 40 (+850 mV) CkM-Cu H2O2 7 0 (-650 mV) 0 (+850 mV) H2O2 12 0 (-650 mV) 63 (+850 mV) Glucose 12 0 (-650 mV) 21 (+850 mV) CkH-Cu H2O2 7 15 (-40 mV) 23 (+850 mV) H2O2 12 34 (-270 mV) 88 (+740 mV) Glucose 12 0 (-650 mV) 224 (+850 mV) CkP-Ag H2O2 7 190 (-570 mV) 0 (+850 mV) H2O2 12 157 (-370 mV) 0 (+850 mV) CkM-Ag H2O2 7 181 (-650 mV) 30 (+850 mV) H2O2 12 158 (-330 mV) 0 (+850 mV) CkH-Ag H2O2 7 226 (-650 mV) 0 (+850 mV) H2O2 12 328 (-280 mV) 0 (+850 mV) The results indicate that some of the compounds are useful as materials for the determination of H2O2 or glucose in aqueous media, particularly those with the ability to detect hydrogen peroxide at neutral pH under biological conditions, indicating their possible application as biosensors. The mechanical properties of a variety of polymers can be improved by incorporating organic or inorganic fillers. Acrylonitrile-Butadiene-Styrene (ABS) is a widely used polymer in the manufacture of automotive parts (34, 35). For this purpose, its rheological properties are modified through the fabrication of compounds made by incorporating nanofillers, among which graphene stands out (21, 36-42). For this purpose, ABS-graphene-like materials derived from coke were prepared with different weight contents of fillers (0.1, 0.5, 1.0, and 5.0 wt% coke in ABS). Specimens were prepared with the ABS compounds, and their Young's modulus, toughness, and percent yield strength were measured. As can be seen in Figure 3, the % elongation at maximum load of ABS compounds with different weight contents of cokes increases significantly in the compounds of 0.1% by weight of CkH (115%), 0.5% by weight of CkM (125%) or with 5% by weight of CkP (100%), indicating that the cokes act as plasticizers and can be used for that purpose in the manufacture of ABS compounds. The following are examples of the manufacture and use of graphene-like materials; the examples should be considered as illustrative of the procedures and their possible variations, and should not be taken as limiting. Example 1 Mechanical exfoliation of cokes by grinding aided with fatty acids. A mixture of 4 g of stearic acid with 2 g of petroleum coke (CkP), metallurgical coke (CkM), or high-temperature coke (CkH) is placed inside the grinding vessel schematically described in Figure 1. A 7.5 kg metal weight with a curved bottom (Figure 1) is placed on top of the mixture, and the mixture is processed for one to four hours using a ManLab planetary mill at 3,600 rpm. After the grinding time, the mixture is deposited at the bottom of the grinding vessel as a thick, black film. The film is removed from the vessel and placed in a 250 mL beaker equipped with a magnetic stir bar; 100 mL of hot toluene is added, and the mixture is stirred for 10 minutes on a heated stirring plate.The material is allowed to settle by removing the supernatant liquid. 100 mL of solvent is added to the solid, and this process is repeated four times. The suspension is vacuum filtered and repeatedly washed with hot ethanol. The solid is then dried at 70 °C for 12 hours in an electric oven. The products are characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy. The XRD and TGA results are shown in Figures 4 and 5, respectively: (4a) starting cokes, (4b) exfoliated cokes 1 h and (4c) exfoliated cokes 4 h and (5a) starting cokes, (5b) exfoliated cokes 1 h and (5c) exfoliated cokes 4 h). Example 2 Graphene-like material nanocomposites with copper or silver nanoparticles with a weight ratio of 1:0.1. 100 mg of petroleum, metallurgical, or high-temperature coke (CkP, CkM, and CkH) are placed in 75 mL of distilled water containing 39.2 mg of copper sulfate pentahydrate (0.157 mM). The resulting suspension is treated for 10 minutes by immersion of the ultrasonic tip of a sonotrode (Q Sonic model Q700) at 60% power. After this time, 1,200 mg of ascorbic acid (6.812 mM) (copper sulfate:ascorbic acid molar ratio 1:43) are added, and the ultrasonic treatment continues for an additional 15 minutes. The suspensions are vacuum filtered, and the solid is washed repeatedly with distilled water and finally with acetone. The products are dried at 70 °C for 12 hours. The preparation of the graphene-Ag type material nanocomposite weight ratio 1:0.1 is done in the same way, replacing the copper salt with silver nitrate (26.67 mg, 0.157 mM). Example 3 Use of graphene-like material nanocomposites with copper or silver nanoparticles for non-enzymatic sensing of H2O2 and glucose. Suspensions of 5 mg / mL of materials prepared according to Example 2 are prepared using distilled water containing 0.1 mg / mL of PEDOT-PSS as the dispersant. Five milliliters of the suspension are deposited onto ECV and used for the electrochemical determination of hydrogen peroxide content (at pH 7 and 12, respectively) or glucose content (at pH 12). Figure 6 shows the streams obtained at pH 7 at different hydrogen peroxide concentrations using the CkP-Ag compound, yielding the rate of change of the material with respect to H₂O₂. Figure 7 shows the streams obtained at pH 12 at different hydrogen peroxide concentrations using the CkH-Ag compound, yielding the rate of change of the material with respect to H₂O₂. Figure 8 shows the streams obtained at pH 12 at different glucose concentrations using the CkH-Cu compound, yielding the rate of change of the material with respect to glucose. ηοΑΑηη / ηζηζ / Ε / γίΛΐ Example 4 Method for obtaining and measuring ABS-graphene-type material compounds Graphene-ABS composites with weight ratios of 0.1, 0.5, 1.0, and 5.0% were prepared at 220 °C for three minutes using an Xplore twin-spindle microprocessor with rotary motion. Dumbbell-shaped specimens, 63 mm long, 3.6 mm wide, and 3.3 mm thick, were injection-molded from the molten mixtures at 220 °C and a pressure of 1.1 MPa. The mold temperature was 45 °C and the pressure was 10 MPa. The toughness of five dumbbell specimens was evaluated using an MTS Criterion Model 43 universal testing machine at a speed of 5 mm / min with a 5 kN load cell, according to ASTM D638.

Claims

1 - Graphene-like materials obtained by mechanical exfoliation of pre-graphitic cokes of different origins. 2 - Process of obtaining the materials indicated in claim 1 by planetary grinding exfoliation treatment of pre-graphitic cokes of different origin, using a container equipped with a massive grinding medium of dimensions adjusted to the size of the treatment container.

3. - Exfoliation treatment process by planetary grinding of pre-graphitic cokes of different origin, according to claim 2, characterized by using a single mass as a grinding medium, instead of the spheres typically used.

4. - Exfoliation treatment process by planetary grinding of pre-graphitic cokes of different origin, according to claims 2 and 3, characterized in that the mass, maintaining the lower curved configuration adjusted to the geometry of the grinding vessel, can be varied in weight by adjusting its height.

5. Process for preparing graphene-like materials from pre-graphitic cokes using a grinding system, according to claim 2, characterized by being carried out in the presence of soft organic solids that act as lubricants and aid in the exfoliation processes.

6. Process for preparing graphene-like materials from pre-graphitic cokes using a grinding system, according to claim 5, characterized in that the soft lubricating solids are natural fatty acids.

7. Process for preparing graphene-like materials from pre-graphitic cokes using a milling system, according to claim 6, characterized by using saturated natural fatty acids with melting points between 50 °C and 70 °C. noRRnn / nznz / R / YiAi 8. A process for preparing graphene-like materials from pre-graphitic cokes using a milling system, according to claim 7, characterized in that the saturated fatty acids can be myristic, palmitic, or stearic acid. Due to their availability, palmitic or stearic fatty acids are preferably used.

9. Process for preparing graphene-like materials from pre-graphitic cokes using a grinding system, according to claims 7 and 8, characterized in that the weight ratio of coke:fatty acid can vary from 1:1 to 1:10, preferably from 1:2 to 1:4 and more preferably from 1:

2.

10. - Process for preparing graphene-type materials from pre-graphitic cokes using a grinding system, according to claims 2 to 9, characterized in that the grinding time can vary from half an hour to 10 hours or more, preferably using times of 1 to 4 hours.

11. - Process for preparing graphene-like materials from pre-graphitic cokes using a grinding system, according to claims 5 to 10, characterized in that after the grinding treatment the graphene-like materials are separated from the exfoliating medium by extraction of the latter with commonly used solvents.

12. A process for preparing graphene-like materials from pre-graphitic cokes using a milling system, according to claim 11, characterized in that the solvent used can be any solvent capable of readily dissolving the fatty acids used. For reasons of accessibility, effectiveness, and environmental safety, ethyl alcohol is preferably used as the solvent for removing the fatty acids.

13. A process for preparing graphene-like materials from pre-graphitic cokes using a milling system, according to claim 12, characterized in that the mixtures are extracted up to 5 times by mechanical stirring in the presence of the solvent heated to its boiling point, decanting the supernatant, and repeating the washing process by adding the solvent again. After the washing process is complete, the solid is vacuum filtered and dried at 50° to 90°C, preferably at 70°C, for several hours.

14. ABS concentrates with graphene-like materials, according to claims 1 to 13, characterized in that they can be used to improve the mechanical properties of acrylonitrile-styrene-butadiene (ABS) compounds.

15. - Process for preparing ABS concentrates with graphene-like materials from pre-graphitic cokes, according to claim 14, characterized in that the ABS-graphene-like material compounds can be manufactured with weight contents of the graphene-like materials from 0.1% to 50%, preferably from 0.1% to 5%.

16. - Process for preparing ABS mixtures with graphene-like materials obtained from pre-graphitic cokes, according to claim 15, characterized in that the compounds are made by melt mixing of ABS with the graphene-like materials, using a twin-screw mixer. 17 - Process for preparing ABS compounds with graphene-like materials from pre-graphitic cokes using a mixing system, according to claim 16, characterized in that the % elongation at maximum load of the ABS compounds with different weight contents of cokes is significantly increased in the compounds of 0.1% by weight of CkH (115%), 0.5% by weight of CkM (125%) or with 5% by weight of CkP (100%).

18. Graphene-like material composites, prepared according to claims 2 to 13, characterized by being decorated with copper and / or silver nanoparticles and being useful in the manufacture of biosensors for the electrochemical measurement of hydrogen peroxide content at pH 7 and pH 12 and glucose at pH 12 in liquid samples.

19. - Process for preparing copper and / or silver nanoparticle compounds from graphene-like materials obtained from pre-graphitic cokes using a grinding and washing system, according to claims 2 to 13, characterized in that the copper or silver compounds with the graphene-like materials can be used in the preparation of electrodes for the electrochemical determination of hydrogen peroxide contents at pH 7 and pH 12 and of glucose at pH 12 in liquid samples.

20. - Process for preparing copper and / or silver nanoparticle compounds with graphene-like materials obtained from pre-graphitic cokes, according to claim 19, characterized in that the compounds can be manufactured by the in situ reduction of aqueous solutions of copper or silver precursor salts in the presence of suspensions of the graphene-like materials.

21. - Process for preparing copper and / or silver nanoparticle compounds with graphene-like materials, according to claim 20, characterized in that the weight ratio of metallic nanoparticle to graphene-like material can be varied in a range of 0.01:1 to 1:1, preferably in a range of 0.05:1 to 0.2:

1. 22 - Process for preparing copper and / or silver nanoparticle compounds with graphene-like materials, according to claim 20, characterized in that the reductions of the metal salts can be carried out by adding solutions of reducing agents to the suspensions of the graphene-like materials under ultrasonic treatment conditions.

23. - Process for preparing copper and / or silver nanoparticle compounds with graphene-type materials, according to claim 22, characterized in that an ultrasound power of 20 to 90% is used. 24 - Process for preparing copper and / or silver nanoparticle compounds with graphene-type materials, according to claim 22, characterized in that the molar ratio of reducing agent:metal cation can be varied from 0.5:1 to 40:1.