Synthesis of High-Quality Ordered Mesoporous Carbons Using a

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Synthesis of High-Quality Ordered Mesoporous Carbons Using a Sustainable Way from Recycling of E-waste as a Silica Template Source Tzong-Horng Liou, and Jhu-Yin Jheng ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b00310 • Publication Date (Web): 20 Mar 2018 Downloaded from http://pubs.acs.org on March 22, 2018

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ACS Sustainable Chemistry & Engineering

Synthesis of High-Quality Ordered Mesoporous Carbons Using a Sustainable Way from Recycling of E-waste as a Silica Template Source

Tzong-Horng Liou1,2,* and Jhu-Yin Jheng1

1

2

Department of Chemical Engineering, Ming Chi University of Technology, 84 Gungjuan Rd., Taishan, New Taipei City 24301, Taiwan

Battery Research Center of Green Energy, Ming Chi University of Technology, 84 Gungjuan Rd., Taishan, New Taipei City 24301, Taiwan

___________________________________________ *To whom correspondence should be addressed. Tel.: +886-2-29089899, ext 4617. Fax: +886-2-29083072. E-mail: [email protected].

1

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ABSTRACT

E-waste has become one of fastest growing waste streams globally. The conversion of e-waste into a valuable nanomaterial is an efficient and sustainable approach toward developing a circular economy. In this study, MCM-48 mesoporous silicas were synthesized from recycled electronic packaging resin waste. Next, ordered mesoporous carbons were synthesized using the MCM-48 template. The influence of synthesis variables, such as the surfactant premixing procedure, cationic surfactant type, isothermal or nonisothermal pyrolysis procedure, pyrolysis time, carbon precursor, and the pre- and post-treatment procedures of samples on the surface properties of carbon materials was investigated. Experimental results confirmed that well-ordered CMK-1 materials with a high purity of 99.94 wt% were successfully synthesized using the resin waste as a silica template source. The resulting mesoporous carbon had a large surface area of 1715 m2/g, a pore volume of 1.02 cm3/g, and a uniform bimodal pore size of 2.33 and 3.86 nm. The carbon structure was sensitive to the pyrolysis temperature, pyrolysis time, and the concentration of sulfuric and hydrofluoric acid. The recycling of e-waste into MCM-48 and CMK-1 materials can reduce environmental pollution as well as achieve economic and social benefit.

Keywords: E-waste, MCM-48, CMK-1, Recycling, Circular economy

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INTRODUCTION

Over the past two decades, the electronics industry has grown rapidly. According to Gartner Inc., the worldwide revenue of the semiconductor industry is estimated to total US$ 401.4 billion in 2017, an increase of 16.8% from that in 2016. The global production of waste electrical and electronic equipment (WEEE or e-waste) is estimated to be 30–50 million tons each year, including old computers, mobile phones, television sets, stereos, and radios. It is expected to grow at an annual rate of 3%–5%.1 Many conventional approaches have been used to treat e-wastes, including reuse and repair and the reduced disposal of residues by incineration and landfilling.2 Nevertheless, e-waste may release toxic metals and polyhalogenated organic compounds, and incineration and landfilling methods result in health risks and environmental contamination.3 Therefore, the exploitation of resources recovered from e-waste to develop a circular economy is a viable long-term solution. Electronic packaging materials are widely used in the encapsulation of electronic devices to protect electronic products, such as integrated circuits (IC). During the packaging process, the residual resins consist of 30–50 wt% of the total resin compound produced.4 Typically, the major components in an electronic packaging material are epoxy resin, phenol resin, silica, and additives. With the increased production of electronic goods, the efficient disposal of packaging resin wastes has become a crucial issue for environment safety. Packaging resin waste contains a high proportion of silica (approximately 80 wt%),5 which is an economically viable source for the mass production of MCM-48 materials. The well-organized MCM-48 silica is beneficial for the synthesis of high-quality ordered mesoporous carbons (OMCs) such as CMK-1. OMCs with pore diameters ranging from 2 to 50 nm exhibit a high surface area, large pore volume, satisfactory chemical inertness, and uniform pore channel. These 3



carbon materials with regular arrays of mesoporous structures have attracted considerable attention such as for catalysis,6 separation,7 energy,8 sensors,9 fuel cells,10 supercapacitors,11 and biomedical materials.12 In 1992, Mobil developed a new mesoporous silica labeled as the M41s family, which contains MCM-41, MCM-48, and MCM-50. MCM-48 possesses a three-dimensional pore system and cubic structure. Compared with the characteristics of MCM-41 materials, those of MCM-48 can reduce pore blockage and provide more efficient mass transfer kinetics in catalytic and adsorption applications.13 The silica material consists of an interconnected pore system that is a valuable candidate to act as a template for achieving OMC materials. However, due to the mesoporous phase being highly sensitive to synthetic conditions, relatively few studies have investigated MCM-48. For example, the formation of surfactant micelles must be strictly controlled in strongly acidic or strongly basic media.14 Numerous studies have examined the preparation and characterization of mesoporous carbon materials by impregnating carbon precursors, such as sucrose, glucose, furfuryl alcohol polymer, or phenol resin, in silica template mesopores. The pore characteristics of OMC are strongly influenced by its carbon precursor and the silica template.15-19 Seo et al.20 studied CMK-3 synthesis by using sulfuric acid or phosphoric acid-impregnated SBA-15 as a template. The mineral acid led to selective carbonization inside the pore walls of the silica template and prevented the generation of external carbon species. Ghani et al.21 studied the optical properties of CMK-1 and CMK-3, which were synthesized using MCM-48 and SBA-15 as templates, respectively. They observed that mesoporous carbons had very high UV-vis absorbance and very low reflectance. These properties made them suitable selections as pigments for black coatings. Inagaki et al.18 synthesized CMK-1 that was partially graphitized for the treatment of furfuryl alcohol polymers in MCM-48 mesopores. 4


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The CMK-1 obtained using the Ni catalyst exhibited a higher electric double-layer capacitance than did normal CMK-1. Recently, the use of solid wastes, such as rice husk ash and coal fly ash from rice milling and coal combustion, respectively, provided potential silica sources (containing approximately 95 wt% silica) for the synthesis of SBA-15 and MCM-48.22-24 These mesoporous silica materials were suitable for use as templates to achieve high-quality OMCs.25 The commercial production of sodium silicate using quartz sand and sodium carbonate at a high temperature of 1300°C consumes considerable quantities of energy.26 By contrast, the method of silica extraction from packaging resin waste is not complicated, and packaging resin waste is an excellent source for preparing nanomaterials, such as MCM-48 and CMK-1, for industrial scale production. Numerous studies have reported the recovery of valuable metals from e-waste.27,28 However, the utilization of silica from e-waste to synthesize MCM-48 and CMK-1 materials have generally been neglected in the literature. Previous studies have provided a detailed analysis of the recovery of packaging resin waste and its application in preparing nanosilica, MCM-41, and MCM-48 materials.14,29-32 In the current study, we attempted to use e-waste to synthesize CMK-1 in three steps. First, sodium silicate solution was extracted from recycled electronic packaging resin waste. Second, the MCM-48 template was synthesized using sodium silicate solution in the presence of a cationic and neutral surfactant mixture. Finally, a carbon precursor was infiltrated into the MCM-48 template and subsequently converted to CMK-1 through pyrolysis, and the silica template was removed. In the current study, synthesis variables, such as the surfactant premixing procedure, cationic surfactant type, isothermal and nonisothermal pyrolysis procedures, pyrolysis time, and carbon precursors, and the pre- and post-treatment procedures of samples, were investigated in detail. The resulting carbon products were analyzed using a small-angle X-ray 5



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scattering (SAXS) system, transmission electron microscope (TEM), field-emission scanning electron microscope (FE-SEM), Fourier transform infrared spectrometer, thermogravimetric analyzer, and N2-adsorption analyzer. The preparation of ordered mesoporous carbon using an environmentally friendly approach enables the effective use of e-waste resources.

EXPERIMENTAL

Materials The electronic packaging resin waste used in this study was obtained from an electronic packaging mill (Siliconwave Precision Co., Taiwan). The basic constituents and properties of resin waste were described by Liou.4,5 The commercial surfactants, namely

dodecyltrimethylammonium

myristyltrimethylammonium cetyltrimethylammonium

bromide

bromide bromide

(C12TAB,

(C14TAB, (C16TAB,

Acros Acros

Acros

Organics), Organics), Organics),

trimethyloctadecylammonium bromide (C18TAB, Sigma-Aldrich), and polyethylene glycol dodecyl ether (C12(EO)4, Sigma-Aldrich), were used as organic templates. Sucrose (C12H22O11), glucose (C6H12O6), and xylose (C5H10O5) were used as carbon precursors (Sigma-Aldrich). Sulfuric acid (H2SO4), hydrochloric acid (HCl), hydrofluoric acid (HF), and sodium hydroxide (NaOH), used as acid and base treatments, were all of analytic grade (Merck, Germany). High purity air and nitrogen were employed as the reaction and purge gases, respectively (Sun Fu Co., 99.995 %).

Extraction of Silica from Electronic Packaging Resin Waste Silica was extracted according to the procedure described in the literature for 6


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using electronic packaging resin waste as a silica source.29 The resin wastes were first ground into fine powders and then heated at 800 oC in air to remove organic matter. The packaging resin ash (denoted as PRA) was obtained after the heating period. The ash was refluxed with 3.0 M HCl solution to remove any metallic impurities. Then, the 50 g of PRA was added to 4.0 M 325 ml of NaOH solution and boiled at 100°C for 6 h with constant stirring. The PRA was converted to sodium silicate solution. The solution was centrifuged and filtered through a glass filter (Whatman PLC, England) to remove any solid residue. This filtration procedure was repeated several times, and a colorless, transparent solution was finally obtained. The undissolved solid residue was approximately 11 g. The observation indicates that 39 g (0.65 mol) of silica was dissolved in the NaOH solution. The general assumption was that the formation of sodium silicate was represented in the following reaction. Therefore, the concentration of sodium silicate solution was 2.0 M. SiO2 + 2NaOH → Na2SiO3 + H2O

(1)

Synthesis of Mesoporous Silica Templates A mesoporous silica template was synthesized using sodium silicate solution from alkali-extracted PRA as a silica source and cationic CnTAB and neutral C12(EO)4 as cosurfactants. The n value of CnTAB varied from 12 to 18. According to the typical procedure, 1.82 g of CTAB and 0.27 g of C12(EO)4 were dissolved in 32 mL of deionized water. The sodium silicate solution was added to the cosurfactant solution by using a magnetic stirrer. A 1.0 M H2SO4 solution was added slowly into the silicate solution. The pH of the mixture was maintained at a constant value of 11, which was monitored using an S20-K pH meter (Metter Toledo). The resulting gel mixture was heated at 100°C for 48 h in a PTFE-lined stainless steel autoclave. The precipitated MCM-48 product was washed with water, filtered, and dried at 100°C for 24 h. The 7



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product was calcined in air at a heating rate of 1°C/min and then maintained at 550°C for 6 h.

Synthesis of Ordered Mesoporous Carbon Ordered mesoporous carbon was prepared using MCM-48 as a template and various carbon precursor sources. In a typical synthesis, MCM-48 was added to an aqueous solution containing sucrose and sulfuric acid. The mixed solution was heated in an oven at 100°C for 6 h and then heated at 160oC for 6 h. The sucrose was converted to a brown solid. An additional amount of sucrose and sulfuric acid was added to compensate for the carbon loss. The sucrose–MCM-48 composite was placed in a quartz reactor and was heated to 900°C (at a heating rate of 10°C/min) under nitrogen atmosphere. The final temperature was maintained for 2 h. After cooling to room temperature, the silica template was removed by dispersing the sample in 10 wt% HF solution. The resulting CMK-1 was obtained by filtering and washing the solid sample repeatedly with deionized water and then drying it at 105°C for 24 h.

Characterization of the MCM-48 and CMK-1 Samples The metallic impurities present in mesoporous silica and carbon samples were determined using an inductively coupled plasma-mass spectrometer (ICP-MS, Kontrin Plasmakon, model S-35). A Heraeus elemental analyzer was employed to determine

the

amount

of

the

fundamental

organic

element.

Nitrogen

adsorption–desorption isotherms were measured at −196°C by using a Micrometrics accelerated surface area and porosimetry (ASAP) 2010 instrument. The specific surface

area

and

pore

size

distribution

were

calculated

using

the

Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods, 8


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respectively. The mesoporous structure of carbon samples was recorded on an SAXS system (Osmic, model PSAXS-USH-WAXS-002). The Fourier transform infrared spectra of samples were characterized using a Shimadzu FTIR-8300 spectrometer. The surface morphology of samples was determined using a JEOL JSM-6700F FE-SEM. High-resolution TEM images were recorded on a JEOL JEM-1200CX II. The weight loss versus pyrolysis temperature of samples for the total carbonization process was recorded using a thermogravimetric apparatus (Mettler, model TGA/SDTA851e). The sample was heated from room temperature to 1000°C at heating rates of 5–30°C/min.

RESULTS AND DISCUSSION

Analysis of Metallic Impurities and Organic Elements The levels of metallic impurities present in PRA, MCM-48, and CMK-1 samples were analyzed using an ICP-MS (Table 1). Sb, Al, Mg, and Fe were present as major impurities in the burned resin (PRA) sample. When MCM-48 was synthesized from alkali-extracted PRA as the silica source, the concentration of metallic ingredients was lower than that of the PRA sample. This was due to the well-dispersed silicate species in the surfactant solution. These metal ions can be easily diffused out of the silica matrix and removed by water-washing and calcination procedures. Following carbonization of the sucrose–MCM-48 composites and the removal of the MCM-48 templates through HF leaching, pure CMK-1 products were obtained. The level of impurities in CMK-1 was lower than that in MCM-48. This is because residual metals may be cached in the MCM-48 matrix and removed using an HF leaching procedure. Table 1 shows the effects of the HF concentration on the amounts of metallic 9



ingredients in CMK-1 samples. The concentration of the remaining metals decreased with an increase in the concentration of HF. The amount of metallic ingredients did not change significantly when the HF concentration was increased from 5 to 20 wt%. This result indicated that an HF concentration of 5 wt% was sufficient for the effective removal of the MCM-48 template. The purity of the CMK-1 material was as high as 99.94 wt%. Table 2 lists the elemental analyses of unpyrolyzed and pyrolyzed mesoporous carbon samples. These carbon samples were obtained using an MCM-48 template, which was extracted from PRA. The major organic elements in the unpyrolyzed sample were carbon, hydrogen, and oxygen. The ash content (mainly silica) was as high as 63.64 wt%. In the pyrolyzed samples, the content of carbon ranged from 80.88 to 93.92 wt% and increased with the pyrolysis temperature. By contrast, the oxygen content ranged from 4.30 to 15.25 wt% and decreased with an increase in the pyrolysis temperature. The ash content dissipated from carbon samples at pyrolysis temperature ranging from 500°C to 1000°C, indicating the complete removal of the silica template. The carbon content of CMK-1 samples was less affected when the pyrolysis temperature exceeded 600°C. This observation indicated that a considerable part of sucrose was converted to carbon.

Effects of Surfactant Premixing Procedure on the Surface and Phase Characteristics of Carbon Samples Figure 1(a) and 1(b) represent the surface area and phase characteristics of silica templates using different surfactant premixing procedures, respectively. For the R-MCM-48 sample, sulfuric acid was mixed with the C16TAB/C12(EO)4 surfactant and subsequently incorporated in the sodium silicate solution. The peak of the SAXS 10


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pattern in Figure 1(b) was only observed at 2Ɵ = 1.8°, which indicates that the R-MCM-48 sample exhibited a less ordered pore structure. The specific surface area of R-MCM-48 was 1020 m2/g. For the MCM-48 sample, the sodium silicate solution was mixed with the C16TAB/C12(EO)4 surfactant. Then, sulfuric acid was added to the silicate solution. The SAXS pattern of the silica product exhibited four reflection peaks at (211), (220), (420), and (332), which were the cubic characteristics of the MCM-48 material.33 The MCM-48 material exhibited a surface area of 1153 m2/g. The hydrogen bonding and stronger van der Waals force constructed the surfactant micelle.32 Then, the cubic mesostructure was formed through the interaction between negatively charged silica and positively charged micelles. For the MCM-41 sample, the sample was synthesized using one C16TAB surfactant. The SAXS pattern revealed an intense diffraction (100) peak and three higher reflections (110, 200, and 210), which were the hexagonal MCM-41 mesostructure.34 The specific surface area of MCM-41 was 1033 m2/g. Figure 1(c) and 1(d) represent the surface area and phase characteristics of carbon materials obtained using different silica templates, respectively. For the R-CMK-1 sample, carbon was synthesized using the R-MCM-48 template. The SAXS pattern in Figure 1(d) displays mainly one diffraction peak, indicating a less ordered pore structure. When the carbon sample was synthesized using the MCM-48 template, the SAXS analysis exhibited three (110, 211, and 220) reflections, indicating a typical CMK-1 cubic structure.18 The CMK-1 carbon exhibited a high surface area of 1392 m2/g. For the MCM-41-templated carbon, the SAXS pattern did not have an ordered porous structure. This observation indicated that MCM-41 is not suitable for use as a template for mesoporous carbon. The specific surface area of MCM-41-C was 1093 m2/g. Based on the results of the silica template synthesized from different surfactant premixing procedures, the phase characteristics of mesoporous carbon were an accurate inverse replica of its template 11



source. The surface area of the three carbon samples were in the order of CMK-1 > MCM-41-C > R-CMK-1. Figure 2 depicts the N2 adsorption–desorption isotherms and pore size distribution of carbon samples obtained from different silica templates. Figure 2(a) reveals that the nitrogen adsorption capacities of the three carbon samples increased in the order of CMK-1 > MCM-41-C > R-CMK-1. The R-CMK-1 sample was characterized by a broad hysteresis loop at a high relative pressure. The isotherm was type IV, a typical mesoporous material. A narrow peak in pore size distribution occurred at 3.87 nm (Figure 2(b)). The carbon sample exhibited a low pore volume of 0.414 cm3/g. The isotherm of MCM-41-C exhibited a stiff increase in nitrogen uptake in the initial pressure range, which indicated the presence of microporous materials.35 When the adsorption increased above 0.5, the isotherm showed a hysteresis loop in the mesoporous structure. However, the pore size distribution of the MCM-41-C sample displayed no obvious peak higher than 2 nm (Figure 2(b)). From this result, it can be inferred that the pore structure of the MCM-41-C sample was mainly microporous. The pore volume of the sample was 0.704 cm3/g. The isotherm of CMK-1 exhibited two well-pronounced capillary condensation steps in the range of P/Po = 0.2–0.3 and 0.4–1.0, which indicated the formation of mesopores with a uniform pore diameter. CMK-1 exhibited a narrow bimodal pore size distribution at 2.44 and 3.92 nm. The sample had a high pore volume of 0.820 cm3/g.

Analysis of the Synthesis Conditions of Ordered Mesoporous Carbon

Effects of the Cationic Surfactant Type The highly ordered MCM-48 was synthesized using a cationic and neutral 12


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surfactant mixture. Figure 3(a) reveals the effects of different cationic surfactants on the surface area of silica templates. The specific surface areas of mesoporous silicas C12–C18MCM-48 ranged from 466 to 1216 m2/g and decreased with an increase in the carbon number of the cationic surfactant. As displayed in Figure 3(b), four different mesoporous silicas were used as templates for the synthesis of mesoporous carbons. The surface area of mesoporous carbon exhibited the same trend as that of the silica template. The higher the surface area of the silica template was, the higher was the formation of the surface area of mesoporous carbon. The mesoporous carbon product was an excellent replica of the porous silica template. In this study, the highest surface area of 1575 m2/g for C12CMK-1 material was recorded. C18CMK-1 had a lower surface area of 841 m2/g.

Effects of Isothermal and Nonisothermal Pyrolysis Procedures Mesoporous carbons were obtained after the carbonization treatment of sucrose and silica precursors. Both isothermal and nonisothermal pyrolysis procedures were employed to evaluate the surface characteristics of mesoporous carbon. For the isothermal pyrolysis procedure, the furnace was first heated and maintained at a constant temperature of 500°C–1000°C; then, the sucrose and silica precursors were placed into the furnace and pyrolyzed for 2 h. Figure 4 (a) illustrates the effects of the isothermal pyrolysis procedure on the specific surface area of mesoporous carbon. In this study, the highest surface area of carbon samples was observed at 700°C. When the pyrolysis temperature was lower than 700°C, the surface area of carbon increased with the pyrolysis temperature. This was due to the release of organic substances from the sucrose–silica composite, leaving a porous surface. However, when the pyrolysis temperature exceeded 700°C, violent gasification reactions may have caused destruction of a part of the pore structure by collapsing or contracting.36 As a result, 13



the surface area of the carbon sample decreased slightly with an increase in the pyrolysis temperature. For non-isothermal pyrolysis procedure, the sucrose–silica precursors were placed into a furnace. The furnace was heated from room temperature to the final carbonization temperature (500–1000°C) at a heating rate of 10°C/min; then, the pyrolysis time was maintained for 2 h. Figure 4(b) displays the BET surface area of carbon samples obtained using a nonisothermal procedure. The highest surface area of carbon sample was also observed at a pyrolysis temperature of 700°C. A comparison of Figure 4(a) and 4(b) indicated that the carbon samples obtained using a nonisothermal procedure had higher surface areas than did those obtained using an isothermal procedure. This may be due to the destruction of pores caused by the sudden heating of the carbon precursor at a high temperature in the isothermal procedure. By contrast, the pores of carbon samples in the nonisothermal procedure were well developed; therefore, an increase in the surface area was observed.

Effects of the Pyrolysis Time and Carbon Precursor Figure 5(a) reveals the effects of pyrolysis time on the specific surface area of carbon samples. In this study, the surface area of carbon decreased with an increase in the duration of pyrolysis. This was due to the fact that the organic matter in the carbon precursor was sucrose. Sucrose was decomposed to carbon when the sucrose–silica composite was heated at a high temperature. As the pyrolysis time continuously increased, the carbon swelled gradually. The thickening of the pore wall reduced the surface area of the carbon sample. A pyrolysis time higher than 2 h had a negligible influence on the surface area, indicating that carbon frameworks were fully developed and stable. Figure 5(b) displays the specific surface areas of the carbon samples that were 14


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obtained from various carbon numbers of organic compounds used as carbon precursors, including xylose (C5H10O5), glucose (C6H12O6), sucrose (C12H22O11), and the cosurfactant (C16TAB/C12(EO)4). The surface area of mesoporous carbon obtained using sucrose as a carbon source was almost the same as that of glucose and xylose. This result indicated that the three carbon sources decomposed rapidly in the mesoporous silica framework and were successfully converted to OMCs. We attempted to use the C16TAB/C12(EO)4 surfactant mixture as a carbon source to replace sucrose. The surface area of directly synthesized carbon material was only 750 m2/g. This observation indicated that the surfactant mixture did not easily infiltrate into silica pores. The excessive amount of surfactant can cause the formation of external carbon species.

Effect of the Carbon Sample Pre- and Post-treatment Procedures In normal circumstances, the hydrophilic nature of sucrose indicates that it does not easily enter template pores surrounded by a hydrophobic silica framework.37 However, the sucrose can be transformed into a less hydrophilic substance by the incorporation of a sulfuric acid catalyst. Figure 6(a) displays the specific surface areas for carbon prepared through the impregnation of the MCM-48 template with sucrose in the presence of various levels of sulfuric acid. The surface area of the carbon sample obtained without the addition of sulfuric acid (H2SO4 = 0.00 g) was only 877 m2/g. This result indicated that the sucrose could not completely infiltrate the template pores. Parts of sucrose pyrolysis outside the template resulted in the formation of nontemplated carbon.20 Nevertheless, the presence of sulfuric acid in the template frameworks resulted in CMK-1 carbons with a high surface area. The observation indicates that sucrose successfully penetrated the template mesopores. The curve demonstrates that surface area did not change significantly due to the incorporation of 15



sulfuric acid ranging from 0.07 to 0.56 g. This means that sucrose can be easily impregnated into template pore walls even by adding only a small amount of sulfuric acid. The acid strength may affect the decomposition rate of sucrose. The highest surface area of 1445 m2/g was observed when the amount of sulfuric acid was 0.56 g. After the carbonization of the sucrose–MCM-48 composite, the MCM-48 template was removed by leaching with the HF solution. Ultimately, the pure CMK-1 carbon was obtained. Figure 6(b) reveals the effects of HF concentration on the specific surface areas of mesoporous carbon after removing the silica template. The surface area of carbon sample obtained without HF leaching was only 82 m2/g. The low surface area value was due to the fact that the silica template was not removed. When carbon samples were obtained by leaching with the HF solution, the surface area increased with the HF concentration. The surface areas did not change significantly for the HF concentration increases from 5.0 to 20.0 wt%. In such cases, an HF concentration of 5 wt% was sufficient for the complete removal of the silica template. This observation is consistent with the analysis results of ICM-MS in Table 1. Mesoporous carbon with a large surface area of 1435 m2/g appeared after leaching silica template with 20 wt% of HF solution. It was possible that a high HF concentration provided a more effective contact area between the HF and silica template, so as to increase the surface area of carbon.

Analysis of the Pore Characteristics of the Sample Table 3 presents the specific surface area and pore volume of PRA samples of 2.72 m2/g and 0.006 cm3/g, respectively. The MCM-48 exhibited a large surface area of 1153 m2/g and a large pore volume of 0.851 cm3/g. The mesopore fraction was as high as 100%. Figure 7(a) and 7(b) display the N2 adsorption–desorption isotherm and pore size distribution of carbon samples for different treatment procedures. Figure 7(a) 16


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depicts the isotherm of CMK-1 carbon for the nonisothermal pyrolysis and a carbonization time of 0 h (Time = 0 h). Two capillary condensation steps were observed in the range of P/Po = 0.2–0.3 and 0.4–1.0. These well-pronounced capillary condensation steps indicated high uniformity in pore size. Figure 7(b) indicates that the mesopore size distribution of CMK-1 carbon (Time = 0 h) was centered at 2.33 and 3.86 nm. The sample exhibited a high specific surface area of 1715 m2/g and a total pore volume of 1.02 cm3/g (Table 3). The mesopore fraction was as high as 95.10%. In this study, we prepared MCM-48 silica from commercial sodium silicate. Then, mesoporous carbon was obtained using the commercial silica template under the same impregnation and carbonization procedures. Compared with CMK-1 obtained from the PRA-extracted template (Figure 2), the commercial silica-templated CMK-1 had a lower N2 adsorption capacity. The sample exhibited a narrow unimodal pore size distribution of 2.32 nm. The specific surface area and pore volume were 1239 m2/g and 0.758 cm3/g, respectively. The mesopore fraction was 86.28 %. The hysteresis loop of the carbon sample was broadened when silica template was impregnated with sucrose without the incorporation of sulfuric acid (H2SO4 = 0.00 g). The mesopore size distribution was centered at 3.90 nm. The surface area (877 m2/g) and pore volume (0.680 cm3/g) without H2SO4-added carbon were considerably lower than those of CMK-1 carbon. After the pyrolysis of the sucrose–MCM-48 composite, the carbon sample obtained without HF leaching (HF = 0 wt%) had the lowest N2 adsorption capacity. Table 3 indicates that the surface area and pore volume of the sucrose–MCM-48 composite were only 82 m2/g and 0.039 cm3/g, respectively. The pore structure of this sample was mainly microporous. This was probably due to the pore volume of carbon being occupied by the silica template. The micropore fraction was as high as 97.44 %. Figure 7(c) and 7(d) display the N2 adsorption–desorption isotherm and pore size 17



Page 18 of 42

distribution of CMK-1 samples synthesized from various types of silica template. These templates were formed using different carbon numbers of cationic surfactant. Figure 7(c) indicates that these isotherms corresponded to a type IV mesoporous structure with a type H2 hysteresis loop.38 The adsorbed volume decreased with an increase in the carbon number of the cationic surfactant. As revealed in Figure 7(d), the bimodal mesopore diameters of the C18CMK-1 sample were centered at 2.29 and 3.89 nm. The C14CMK-1 and C16CMK-1 samples were also markedly uniform with bimodal pore sizes of 2.44 and 3.92 nm, respectively. The large pore size can provide advantages for allowing more rapid mass transfer of large size of molecules or ions diffusion within OMC particles. The small pore size can provide much more activity sites due to increase the surface area for the adsorption of molecules or ions. Meanwhile, the pore size distribution of the C12CMK-1 sample exhibited only one broad peak, centered at 3.83 nm. The results of the specific surface area, pore volume, and mesopore fraction of CMK-1 samples obtained from different silica templates are summarized in Table 3. The carbon number of the cationic surfactant significantly affected the development of the carbon samples’ pore structure. The pore volume of C12–C18CMK-1 samples were in the range of 0.534–0.930 cm3/g, which increased in the order of C12CMK-1 > C14CMK-1 > C16CMK-1> C18CMK-1. These samples show a high mesopore fraction between 80.65% and 88.16%.

Observation

of

Sample

Composition,

Thermal

Property

and

Surface

Morphology As revealed in Figure 8(a), the SAXS patterns of C12–C18CMK-1 samples exhibited two well-resolved reflection peaks, which are the characteristics of highly ordered CMK-1 carbon with a cubic mesostructure.18 In particular, the intensities of two peaks for C18CMK-1 product were relatively weak. This is due to the fact that 18


Page 19 of 42 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


parts of the surfactant micelle may be destroyed by the introduction of the cationic C18TAB surfactant.32 As a result, the ordered structure of carbon sample was not well replicated from the silica template. Figure 8(b) depicts the FTIR spectra of the typical CMK-1 material that were collected using C16MCM-48 as a silica template. The wide band located at approximately 3400 cm−1 was related to OH hydroxyl groups or adsorbed water.39 The peak at approximately 1605 cm−1 corresponded to the C=C vibration. The stretching vibrations of -CH3 were located at 1375 cm−1. The band at approximately 870 cm−1 was a consequence of C-H vibrations. Figure 9 displays the thermogravimetry (TG) and differential thermogravimetry (DTG) curves of as-synthesized sucrose–silica composites for various heating rates. The mass loss in the TG curves is attributed to the evolution of water and organic matter. The mass loss increased with a decrease in the heating rate. The residual mass of samples at each heating rate slowly decreased when the pyrolysis temperature increased. This may be attributed to the high porosity of the pore structure of silica templates. A longer heating duration is necessary to release volatile matter. Three main mass losses occurred when heating the sucrose–silica samples. The mass loss at temperatures below 150°C was due to the evaporation of water molecules in the composites. The mass loss at temperatures ranging from 150°C to 710°C may be associated with the decomposition of organic matter in carbon precursors. Upon further heating from 710°C to 1000°C, the small mass loss in this stage was due to the pyrolysis of residual organic compounds. The DTG curves revealed two peak temperatures in each heating curve. The first peak temperature was 75–109oC and the second peak temperature was 411–456oC. The peak high and position were very sensitive to the heating rate. The peak position shifted to a greater range of temperature as the heating rate increased, and the peak height also increased. Liou et

19



al.40 reported the thermal decomposition of rice husk in air and reached the same conclusion. Figure 10 displays the FE-SEM images of MCM-48 and mesoporous carbon samples. Figure 10(a) and 10(b) shows the SEM image of MCM-48 particles, with mainly a rectangular morphology and particle sizes of 200–500 nm. Similar morphologies are also observed in the study of Uhlig et al.,41 in which MCM-48 was synthesized through the pseudomorphic transformation of porous glasses. Figure 10(c)–10(d) reveal the morphological features of an unpyrolyzed sucrose-silica composite. Figure 10(c) depicts the outer surface of the composite, which is corrugated and contains no hole on the surface of sample. Enlarging the SEM image, Figure 10(d) clearly indicates that sucrose and silica were uniformly mixed together. Figure 10(e)–10(f) display the CMK-1 carbon obtained after pyrolysis and the HF leaching of the carbon-silica composite. Several large cavities were present on the surface of carbon sample (Figure 10(e)). This indicated that the carbon material contained a highly porous structure. Figure 10(f) indicates that these CMK-1 particles were formed through the aggregation of small particles, which exhibited a similar appearance to that of MCM-48.42 Figure 10(g) presents the surface morphology of carbon material obtained from the MCM-41 template, which consisted of fine and flat particles. By enlarging the SEM image it can be clearly observed in Figure 10(h) that the surface of MCM-41-C particles were covered with a fine layer of silk threads. Figure 10(i) and 10(j) illustrate the direct synthesis of mesoporous carbon from the pyrolysis of the surfactant–MCM-48 composite. In the proposed method, we employed the C16TAB/C12(EO)4 surfactant as a carbon precursor to substitute sucrose. Figure 10(i) demonstrates that this carbon material was a hollow and spherically solid. Figure 10(j) depicts the surface of solid consists of lamellar structure. This carbon material is not an ordered porous structure, which has been confirmed by SAXS 20


Page 20 of 42

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analysis (data not shown). This result indicates that the cosurfactant was not allowed to penetrate the silica mesopores. The representative TEM images of MCM-48 and CMK-1 particles are presented in Figure 11. Figure 11(a) provides a low-resolution image of MCM-48 particles, which consisted of a large-scale rectangular shape. The internal morphology of MCM-48 observed in Figure 11(b) displays a regular array of a mesoporous structure. As shown in Figure 11(c), the CMK-1 obtained using MCM-48 as a template and sucrose as a carbon source also exhibited a rectangular particle morphology (> 300 nm). The carbon material was exactly inverse to the MCM-48 template. Figure 11(d) depicts the carbon particle with a uniform tissue of parallel channels, which consisted of highly ordered mesopores. On the other hand, glucose was used as a carbon source to substitute sucrose. Figure 11(e) displays a uniform tissue of parallel channels on the (110) direction. Hosseini et al.43 observed similar morphologies. Figure 11(f) presents a well-ordered array of mesopores with a uniform pore size on the (100) direction. The material exhibited a mesopore size of 4.21 nm, which was almost the same as the calculated pore size of 3.92 nm using the N2-adsorption measurement (Figure 7(d)). No external carbon was apparent on the surface of OMC, which confirmed that the amount of sucrose and glucose was just sufficient to fill the total pore volume in a MCM-48 template.

CONCLUSIONS

A simple, green route method was employed to create CMK-1 carbon, which was synthesized using sucrose-impregnated MCM-48 as a template. The MCM-48 was obtained using cheap, recycled silica from electronic packaging resin ash. The 21



CMK-1 material possessed a purity level as high as 99.94 wt%. The surface areas of mesoporous carbon were very sensitive to the type of cationic surfactant used, pyrolysis temperature and time, concentration of the sulfuric and hydrofluoric acid solution. There were distinctly different carbon surface characteristics when silica templates were synthesized using various surfactant premixing procedures. The SAXS patterns and TEM images demonstrate that CMK-1 carbon was exactly inverse to the MCM-48 template. The carbon material consisted of large-scale rectangular particles with a well-ordered array of mesopores. Using a sustainable method for producing CMK-1 materials from recycling of electronic packaging resin waste as a MCM-48 template source addresses a critical environmental concern. This method of achieving high-quality OMC materials provides valuable knowledge for the development of a circular economy.

ACKNOWLRDGMENTS

The author expresses thanks to the Ministry of Science and Technology (MOST) for its financial support under Project No. MOST 106-2221-E-131-029.

REFERENCES

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(35) Liou T. H.; Hung, L. W.; Syu H. S.; Chu, L. Synthesis of TiO2 nanoparticles and good dispersion on SBA-15 mesoporous materials for high photocatalytic activity. J. Nanosci. Nanotechnol. 2018, 18(1), 20-29. (36) Liou T. H.; Wu S. J. Characteristics of microporous/mesoporous carbons prepared from rice husk under base- and acid-treated conditions. J. Hazard. Mater. 2009, 171, 693–703. (37) Joo, S. H.; Jun, S.; Ryoo, R. Synthesis of ordered mesoporous carbon molecular sieves CMK-1. Microporous Mesoporous Mat. 2001, 44-45, 153-158. (38) Rivoira, L.; Juárez, J.; Falcón, H.; Costa, M. G.; Anunziata, O.; Beltramone, A. Vanadium and titanium oxide supported on mesoporous CMK-3 as new catalysts for oxidative desulfurization. Catal. Today 2017, 282, 123-132. (39) Guo, Y.; Rockstraw, D. A. Activated carbons prepared from rice hull by one-step phosphoric acid activation. Microporous Mesoporous Mat. 2007, 100 (1-3), 12-19. (40) Liou T. H.; Wu, S. J. Kinetics study and characteristics of silica nanoparticles produced from biomass-based material. Ind. Eng. Chem. Res. 2010, 49, 8379–8387. (41) Uhlig, H.; Muenste, T.; Kloess, G.; Ebbinghaus, S. G.; Einicke, W. D.; Gläser, R.; Enke, D. Synthesis of MCM-48 granules with bimodal pore systems via pseudomorphic transformation of porous glass. Microporous Mesoporous Mat. 2018, 257, 185-192. (42) Kaneda, M.; Tsubakiyama, T.; Carlsson, A.; Sakamoto, Y.; Ohsuna, T.; Terasaki, O.; Joo, S. H.; Ryoo R. Structural study of mesoporous MCM-48 and carbon networks synthesized in the spaces of MCM-48 by electron crystallography. J. Phys. Chem. B 2002, 106, 1256–1266 (43) Hosseini, B.; Nourbakhsh, A. A.; MacKenzie, K. J. D. Magnesiothermal synthesis of nanostructured SiC from natural zeolite (clinoptilolite) and mesoporous carbon CMK-1. Ceram. Int. 2015, 41(7), 8809-8813.

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Page 26 of 42

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Table 1 Amount of metallic ingredients in the PRA, mesoporous silica, and mesoporous carbon samples Metallic ingredients as oxides, ppm Na

Sb

K

P

Au

Fe

Mg

Al

Cr

Ag

total

PRAa

87

6100

8

75

8

92

101

501

9

9

6989

MCM-48b

ND

759

ND

2

ND

124

ND

430

3

ND

1318

CMK-1-0%c

ND

828

ND

ND

ND

77

ND

379

13

ND

1297

CMK-1-1%c

ND

648

ND

ND

ND

61

ND

464

10

ND

1183

CMK-1-5%c

ND

667

ND

ND

ND

ND

ND

220

ND

ND

887

CMK-1-10%c

ND

558

ND

ND

ND

ND

ND

179

2

ND

739

CMK-1-20%c

ND

486

ND

ND

ND

ND

ND

164

ND

ND

650

a

Raw resin was heated in air.

b

Mesoporous silica was synthesized from alkali-extracted PRA as a silica source, and cationic C16TAB and neutral C12(EO)4 as the co-surfactants.

c

OMC products obtained by HF leaching with concentrations of 0 – 20 wt%.

27



Page 28 of 42

Table 2 Elemental composition of the unpyrolyzed and pyrolyzed mesoporous carbon samples Composition, wt %

a b

C

H

Oc

N

Ashd

Unpyrolzeda

32.78

2.25

1.33

0.00

63.64

CMK-1-500b

80.88

3.60

15.25

0.00

0.00

CMK-1-600b

90.80

4.13

5.07

0.00

0.00

CMK-1-700b

91.42

3.25

5.33

0.00

0.00

CMK-1-900b

93.42

1.72

4.86

0.00

0.00

CMK-1-1000b

93.92

1.78

4.30

0.00

0.00

Sucrose–MCM-48 composite with unpyrolyzed treatment. OMC products obtained by non-isothermal pyrolysis at temperature range of 500 – 1000 oC, and silica templates were removed by leaching with the HF solution.

c

by difference.

d

by TGA.

28


Page 29 of 42 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


Table 3 Surface area, pore volume and pore diameter of PRA, mesoporous silica, and mesoporous carbon samples for different treatment procedures SBET

Vt

2

Vmic

3

3

Vmeso

Vmeso/Vt

3

(m /g)

(cm /g)

(cm /g)

(cm /g)

(%)

PRA

2.72

0.006

0.000

0.001

16.67

MCM-48

1153

0.851

0.000

0.851

100.00

Time = 0 h

1715

1.02

0.05

0.970

95.10

Commercial

1239

0.758

0.104

0.654

86.28

H2SO4 = 0.00 g

877

0.680

0.079

0.601

88.38

HF = 0 wt%

82

0.039

0.038

0.001

2.56

C12CMK-1

1534

0.930

0.180

0.750

80.65

C14CMK-1

1437

0.836

0.099

0.737

88.16

C16CMK-1

1392

0.820

0.103

0.717

87.44

C18CMK-1

841

0.534

0.099

0.435

81.46

SBET = BET surface area, Vt = total pore volume, Vmic = micropore volume, Vmeso = mesopore volume.

29



Figures captions

Figure 1. Effect of surfactant premixing procedure on surface area and phase characteristic of samples: (a) and (b) silica powders; (c) and (d) carbon powders. Figure 2. (a) Nitrogen adsorption-desorption isotherm and (b) differential pore size distribution of mesoporous carbon samples synthesized from different of silica templates. Figure 3. Effect of cationic surfactant type on the surface area of samples: (a) silica powders and (b) carbon powders. Figure 4. Effect of pyrolysis procedure on the surface area of carbon powder: (a) isothermal procedure and (b) nonisothermal procedure. Figure 5. Effect of (a) pyrolysis time and (b) carbon precursor on the surface area of carbon powders. Figure 6. Effect of concentrations of (a) sulfuric acid and (b) hydrofluoric acid on the surface area of carbon powders. Figure 7. Nitrogen adsorption-desorption isotherm and differential pore size distribution of mesoporous carbon samples: (a) and (b) different treatment procedures; (c) and (d) different types of silica template. Figure 8. (a) SAXS patterns for mesoporous carbon synthesized by different types of silica template; (b) FTIR spectra of mesoporous carbon sample. Figure 9. (a) TG and (b) DTG thermograms of as-synthesized sucrose–silica composite at various heating rates. Figure 10. FE-SEM images of samples: (a) and (b) MCM-48 silica; (c) and (d) unpyrolyzed sucrose–silica composite; (e) and (f) CMK-1 carbon; (g) and (h) carbon sample obtained using a MCM-41 as template; (i) and (j) carbon sample obtained from direct pyrolysis of surfactant–silica composite. Figure 11. High-resolution TEM images: (a) and (b) MCM-48; (c) and (d) CMK-1 obtained using sucrose precursor; (e) and (f) CMK-1 obtained using glucose precursor.

30


Page 30 of 42

(b) Intensity (a.u.)

1200

(a)

1 R-MCM-48 2 MCM-48 3 MCM-41

800

400

1 (211) (220) (420) (332)

2

(100)

(110) (200) (210)

3

0

1

2

1

3

4 R-CMK-1 5 CMK-1 6 MCM41-C

5

7

9

(d)

(c)

4

Intensity (a.u.)

1600

3

Bragg angle (2 Theta)

Number of sample

Surface area (m2/g)

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


Surface area (m2/g)

Page 31 of 42

1200

800

(110) (211) (220)

5

400

6 0

4

5

1

6

3

5

7

9


Number of sample Figure 1

31


(a)

500

Page 32 of 42

II III

250

I I R-CMK-1 II CMK-1 III MCM-41-C

0 0.0

0.5

1.0

P/Po

(b)

II

8.0

dVp/dDp, x100

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

Volume adsorbed (mL/g)


6.0 I R-CMK-1 II CMK-1 III MCM-41-C

4.0 III I

2.0 0.0 2

3

4

Dp (nm) Figure 2

32


5

6

Page 33 of 42

Surface area (m2/g)

1300

(a)

850

1 2 3 4

C12MCM-48 C14 MCM-48 C16MCM-48 C18 MCM-48

400

1

2

3

4

Type of silica template 1650

Surface area (m2/g)

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


(b)

1200

1 2 3 4

C12CMK-1 C14CMK-1 C16CMK-1 C18CMK-1

750

1

2

3

Type of carbon Figure 3

33


4


Surface area (m 2/g)

1500

(a)

1150

800 500

600

700

800

900

1000

900

1000

o

Temperature ( C) 1500

Surface area (m2/g)

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 34 of 42

(b)

1150

800 500

600

700

800 o

Temperature ( C) Figure 4

34


Page 35 of 42


1750

(a)

1500

1250 0

4

8

12

16

Time (h) 1500


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


(b)

1100

1 Xylose 2 Glucose 3 Sucrose 4 C16TAB/C12 (EO) 4

700 1

2

3

Type of carbon precursor

Figure 5

35


4


Surface area (m2/g)

1500

(a)

1 2 3 4 5

1150

H2SO4 H2SO4 H2SO4 H2SO4 H2SO4

= 0.00 g = 0.07 g = 0.14 g = 0.28 g = 0.56 g

800

1

2

3

4

5

H2SO4 concentration 1550

Surface area (m2/g)

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 36 of 42

(b)

1 2 3 4 5

775

HF = 0 wt% HF = 1 wt% HF = 5 wt% HF = 10 wt% HF = 20 wt%

0

1

2

3

HF concentration Figure 6

36


4

5

Page 37 of 42

12.0 I

(a)

(b)

I

500 II III

250 IV

0 0.0

I Time= 0 h II Commercial III H2SO4= 0.00 g IV HF= 0 wt%

dVp/dDp, x100


750

8.0

I Time= 0 h II Commercial III H2SO4= 0.00 g

II

4.0 III

0.0 0.5

1.0

2

3

P/Po 600

(c)

4

5

6

Dp (nm)

I

III

8.0

(d)

II

dVp/dDp, x100


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


III

400

IV

200

0 0.0

I C12CMK-1 II C14CMK-1 III C16CMK-1 IV C18CMK-1

II

I C12CMK-1 II C14CMK-1 III C16CMK-1 IV C18CMK-1

4.0 I IV

0.0 0.5

1.0

P/Po

2

3

4

Dp (nm)

Figure 7

37


5

6


(a) Intensity (a.u.)

C12CMK-1

C14CMK-1

C16CMK-1

C18CMK-1

0

2

4

6

8

10


(b)

Intensity (a.u.)

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 38 of 42

500

1000

2000

3000

Wavenumber (cm-1 )

Figure 8

38


4000

Page 39 of 42

W/Wo

1.0

0.8

(a) I 5 oC/min o II 10 C/min III 15 oC/min IV 20 oC/min o V 30 C/min

IV

V III II I

0.5 200

400

600

800

0.0

dW/dt

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


1000

(b) I II III

-0.0

IV

V

-0.0 200

400

600 o

T ( C) Figure 9

39


800

1000


(a)

(b)

(c)

(d)

(e)

(f)

(g)

(h)

(i)

(j)

Figure 10

40


Page 40 of 42

Page 41 of 42 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


(a)

(b)

(c)

(d)

(e)

(f)

Figure 11

41



TOC/Abstract Graphic

IC packaging material

Crushed Resin waste

Alkali extraction

Na2SiO3

CMK-1

MCM-48

Surfactant micelles

Synopsis A simple, green route method was employed to create CMK-1 carbon, which was obtained using cheap, recycled silica template from e-waste.

42


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Synthesis of High-Quality Ordered Mesoporous Carbons Using a

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