An Optimized Process for Recycling Silicon Chemical Compounds

Subscriber access provided by Washington University | Libraries

Process Systems Engineering

An optimized process for recycling silicon chemical compounds from agroindustry solid waste Joziane Gimenes Meneguin, Paulo Bruns, Cleiser Thiago Pereira da Silva, Murilo Pereira Moises, Marcos Rogério Guilherme, Eduardo Radovanovic, and Andrelson Wellington Rinaldi Ind. Eng. Chem. Res., Just Accepted Manuscript • Publication Date (Web): 20 Feb 2019 Downloaded from http://pubs.acs.org on February 20, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 19 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

Industrial & Engineering Chemistry Research

An optimized process for recycling silicon chemical compounds from agroindustry solid waste Joziane Gimenes Meneguina, Paulo Henrique Galves Brunsa, Cleiser Thiago Pereira da Silvaa, Murilo Pereira Moisésa,b, Marcos Rogério Guilhermea,c, Eduardo Radovanovica, Andrelson Wellington Rinaldia* aMaterials

Chemistry and Sensors Laboratory – LMSen, Chemistry Department,

State University of Maringá - UEM, Av. Colombo 5790, CEP. 87020-900. MaringáPR, Brazil. bFederal

University of Technology of Paraná-UTFPR, Rua Marcílio Dias, 635,

CEP. 86812-460. Apucarana-PR, Brazil. cCesumar

Institute of Science, Technology and Innovation - ICETI, Av. Guerdner,

1610, Jd. Aclimação, Maringá, Paraná, Brazil

∗ Corresponding author. Phone: +55443011-5098; fax: +55443011-4125.

E-mail address: [email protected] (Andrelson Wellington Rinaldi).

1 ACS Paragon Plus Environment


Page 2 of 19

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 3 of 19 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


ABSTRACT In this research, an improved approach for recycling silicon chemical compounds from agroindustry solid waste (sugarcane bagasse ash) was demonstrated. Response surface methodology (RSM), a statistical model, was used to optimize the procedure of silicon extraction by alkaline fusion. RSM and the experimental results demonstrated that the best conditions for alkaline fusion are a fusion time of 40 min, fusion temperature of 550◦C, and alkali:ash ratio of 1.0. The agroindustry solid waste was used as a silicon source to obtain SBA-15 materials with different hydrothermal synthesis times at 0, 6, 18, and 66 h. Furthermore, the textural properties, such as the pore size and specific surface area, could be tuned in the ranges of 424-722 m2.g-1 and 4.2-5.1 nm, respectively. This work contributes to research on environmentally friendly materials, and provides guidance on using other wastes for chemical recycling. Keywords: Agroindustry solid waste; environment-friendly; recycling; SBA-15.


Industrial & Engineering Chemistry Research 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 4 of 19

1. Introduction Sugarcane bagasse (SCB) is one of the many wastes produced in the sugar and ethanol industries. As a way to dispose SCB waste, the sugarcane industry uses it as a combustible fuel for the production of steam and electricity. However, SCB combustion produces sugarcane bagasse ash (SCBA), another hazardous solid waste1. SCBA is inorganic waste, mainly comprising quartz (SiO2), which, if disposed incorrectly in soil, can acidify and contaminate water, thereby causing serious environmental problems. Currently, after the United States, Brazil is the second-largest producer of ethanol in the world2 and the only country developing a program for ethanol production as a green fuel3. Therefore, the production of large amounts of solid wastes by the sugarcane industry and the improper disposal of those solid wastes are not an environmental problem in Brazil alone. Many other research groups worldwide4-6 have been developing promising strategies to use different solid wastes with a high content of silicon, as a silicon source for the synthesis of silicate porous materials such as zeolites7-9, ZSM-510, hydroxysodalite9, Na-P111, 12, and zeolite A13. Besides environmental protection, the use of industrial wastes as a silicon source to produce materials may add value to these wastes, enabling the development of new procedures for the recovery of chemical elements from wastes and reuse. In previous studies, SCBA was used as an alternative source of silicon to synthesize microporous14 and mesoporous materials15, 16, and applied to organic reactions, such as -amine phosphonates synthesis 15. In most studies cited above, inorganic solid waste such as SCBA had to be converted to a soluble silicon source such as [SiOx(OH)4-2x]n to obtain a silicon acid chemical compound. As previously mentioned, SCBA agroindustry waste is composed of (SiO2) quartz particles, which can be dissolved by an alkaline fusion method. In a typical procedure, certain amounts of SCBA and sodium hydroxide (NaOH) are thermally treated at a determined temperature and time, to form a powder. This powder can be dissolved in deionized water to then be used as a silicon solution source. In this alkaline extraction method, parameters such as the ratio between the waste material, sodium hydroxide, fusion temperature, and time may affect the silicon acid extraction yield. For example, if one uses either less sodium hydroxide or low temperature, the silica acid yield will be low. On the other hand, if excess sodium hydroxide and high temperature are used for the alkaline fusion, the process is certain to


Page 5 of 19 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


work; however, a highly alkaline chemical compound will be obtained. This could pose a problem, depending on the porous material synthesis. Therefore, the parameters for silica fusion extraction can be optimized using an experimental design called “one factor at a time” (OFAT), where one parameter is changed, and the others are kept constant. The disadvantages of this optimization technique are that it does not consider the interactive effects among the variables studied; hence, one can miss optimal settings of the factors, and more experimental runs could be necessary17. A statistical factorial experimental design can avoid the disadvantages of OFAT. Chemometric tools such as response surface methodology (RSM)17 and central composite rotatable design (CCRD) are good mathematical and statistical candidates to obtain empirical models and experimental design data for silicon extraction fusion from SCBA. Among the different types of mesoporous silica is SBA-15, an amorphous material synthesized at the University of California in Santa Barbara by Stucky et al. in 199818. The material SBA-15 has a uniform pore structure, high specific surface area, large pore volume, and thermal and chemical stability19-24. Because of these characteristics, the synthesis of porous SBA-15 using SCBA waste as a silicon source is promising for recycling silicon chemical compounds from hazardous waste. Therefore, in this work, an optimized experimental method fitted and evaluated by RSM and CCRD chemometric tools to obtain silicon from SCBA wastes is described. Silicon was used in the synthesis of the mesoporous material SBA-15 by a hydrothermal method, and the time required for the hydrothermal synthesis was studied. 2. Experimental Section 2.1. Silicon extraction optimization 2.1.1 Raw material: sugarcane bagasse ash (SCBA) Sugarcane bagasse ash (SCBA) was collected from a sugarcane industry in the region of Maringá City, Paraná, Brazil. This material was placed in a horizontal furnace and heated at a rate of 20°C min−1 from room temperature to 600°C and maintained for 4 h. 2.1.2. Experimental model design for response surface methodology (RSM) Briefly, a random setup of 18 experiments was carried out, and the experimental planning response was calculated by the silicon extraction determined from flame atomic 5 ACS Paragon Plus Environment


Page 6 of 19

absorption spectroscopy (FAAS) — see the Supporting Information (SI) section for more details. The factors, namely fusion temperature (°C), fusion time (h), and NaOH:SCBA ratio were used in the RSM and CCRD. 2.1.3 Response surface procedure evaluation The models, factors, coefficients, and residues were evaluated by analysis of variance (ANOVA). The polynomial fitting quality model was evaluated by the determination coefficient (R2). 2.2 Synthesis of mesoporous material SBA-15 2.2.1 Silica extraction from raw SCBA after optimized procedure In a nickel crucible, 3.0 g of SCBA and 4.5 g of NaOH (1.5 w/w) were mechanically mixed to obtain a homogeneous mixture. Subsequently, this mixture was exposed to thermal treatment at 550°C for 40 min, to form a fused mixture. 2.2.2 Synthesis of mesoporous material SBA-15 The resultant fused mixture was dissolved in 60 mL of distilled water to obtain a solution (Solution 1). Then, 3.0 g of a triblock copolymer (EO20PO70EO20, EO = ethylene oxide, PO = propylene oxide, Pluronic P-123, Sigma Aldrich) was dissolved in 23 mL of water, followed by the addition of 90 mL of HCl (2.0 mol L-1). This solution was stirred at 40°C until a homogeneous solution was formed (Solution 2). Subsequently, Solution 2 was added to Solution 1 under stirring at 40°C for 24 h. The resulting mixture was added to stainless-steel autoclaves coated with Teflon®, and the syntheses were carried out in hydrothermal conditions at 90°C for 6 h, 18 h, and 66 h. One sample without thermal treatment was also collected (Sample 0 h). The products were recovered, filtered, and dried at 80°C for 4 h and calcinated at 550°C for 6 h. 2.3. Characterization 2.3.1 Low-angle powder X-Ray diffraction (low-angle PXRD) Diffraction patterns were collected in a Bruker D8-Advance using CuKα monochromatic radiation λ = 1.5418 Å, at 40 kV and 40 mA, in the range of 0.5 < 2θ > 5°, step 0.01°, and 2 s/step. 6 ACS Paragon Plus Environment

Page 7 of 19 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


2.3.2 Fourier transformed infrared (FT-IR) spectroscopy The infrared spectra were obtained using KBr pellets on a BOMEM-Michelson MB-100 equipment in the region of 400–4000 cm−1 with a resolution of 2 cm−1. 2.3.3 Scanning electron microscopy (SEM) SEM images were obtained using a Shimadzu Superscan SS-550 microscope. The sample was coated with gold by sputtering. 2.3.4 Transmission electron microscopy (TEM) TEM analysis was performed with a JEOL – JEM 1400 microscope operated at 120 kV. The sample was dissolved in isopropyl alcohol and dropped in a lacey carbon copper grid. 2.3.5

29Si

Solid-state nuclear magnetic resonance cross polarized magic angle spinning

(29Si- solid NMR-CP MAS) Solid-state

29Si-NMR-CP

MAS spectra were recorded in a Varian Mercury Plus BB

500-MHz spectrometer operating at a frequency of 59.61 MHz. 2.3.6 Textural measurements The N2 adsorption and desorption isotherms were collected at 77 K with an ASAP 2020 – Micrometrics. Before the measurements, approximately 200 mg of the samples was activated by the thermal method at 300°C under vacuum for 4 h. 2.3.7 Flame atomic absorption spectroscopy (FAAS) Silicon extraction was determined by FAAS in a Varian SpectrAA 50B atomic absorption spectrometer. 3.0 Results and discussion 3.1 RSM experiments and model fitting Results for the RSM method calculated by ANOVA using a cubic model adjusted to the silicon extraction are shown in Table 1. Silicon dissolution can be expressed by the equation: silicon dissolution (%) = 79 - 7C - 3A2 - 4B2 - 7C2 + 11AB + 6AC - 8BC + 5C3 7 ACS Paragon Plus Environment


Page 8 of 19

6ABC. The regression model presents an F ratio of 41.01, which is higher than the tabulated value of F = 0.05(12,4) = 5.91. The regression p-value obtained (0.0013) is less than 0.05. Therefore, according to the F ratio and p-value, the quadratic model adjusted for silicon dissolution is significant. Additionally, the lack of fit presents an F ratio and p-value of 0.7 and 0.4639, respectively. The F ratio is less than the tabulated value (F = 0.05(1,3) = 10.13) and the p-value is higher than 0.05, indicating that the lack of fit is insignificant. The determination coefficient (R2) of 0.9926 indicates that the regression model explains 99.26% of variations on average, leaving 0.74% for the residues. Table 1. Variance analyses (ANOVA) of the cubic model adjusted to the quartz dissolution results Source

Sum of squares

Model

6417.04

Lack of fit Pure error

DF

Mean square

F value

Prob > F

9

713.00

20.86

< 0.0001

246.05

5

49.21

1.61

0.2015

642.67

21

30.60

R2

0.8784

DF = degree of freedom, R2 = determination coefficient.

Figure 1 shows the relationship between the values predicted by the model and the experimental values for the three CCRD responses. The fusion temperature, fusion time, and fusion NaOH/SCBA ratio can influence the yield response. The best fusion temperature condition, in a temperature range of 400 to 700°C, as determined by the quadratic model, was found to be 550°C. At lower or higher temperatures, the quartz dissolution decreases, probably due to the lack or excess of energy, respectively. Temperatures lower than 550°C indicate a lack of energy for the alkaline fusion and, consequently, an incomplete quartz dissolution. Temperatures higher than 550°C imply excess energy. In this case, a higher temperature can increase the viscosity of the fused sodium hydroxide and increase the SiO2 concentration in the solution by decreasing the hydroxide mobility in this fused solution. The NaOH/SCBA ratio and fusion time do not significantly influence the RSM response model; thus, to achieve a low-cost synthesis process using a lower amount of chemical products in the silicon dissolution process and perform this process for less time, an NaOH:SCBA ratio of 1 and fusion time of 40 min were considered the best conditions. 8 ACS Paragon Plus Environment

Page 9 of 19 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


Figure 1. Relationship between the predicted and observed values of quartz dissolution. Inset: color gradient describing a range of position-related colors; cold colors correspond to lower values and hot colors refer to higher values. Therefore, the optimized conditions are a fusion temperature of 550°C, fusion time of 40 min, and NaOH/SCBA ratio of 1.0. This result is important to explain that durations up to 40 min are not necessary for alkaline fusion, and thus, can lower the costs of this process. 3.2 Results for characterization of SBA-15 mesoporous material The mesoporous material SBA-15 that precipitated in different synthesis times (0 h, 6 h, 18 h, and 66 h) was first evaluated by SEM and TEM analyses. SEM images (SI Figure 1) show that all the synthesized materials possess a macrostructure of ropelike domain morphology, which is due to the copolymer present in the reaction synthesis. SBA-15-0 h was not exposed to hydrothermal synthesis in the stainless-steel autoclaves at 90°C; nevertheless, this material was left stirring at 40°C for 24 h, implying that there was sufficient time to arrange Pluronic P 123 to obtain ropelike domains with a silica condensation reaction. The ropelike morphology indicates that all materials have some porosity and at least primary hexagonal mesoporous arrays. Therefore, to visualize the primary mesoporous channel from this SBA-15 material, TEM was required. Figure 2 shows the TEM images obtained for all the materials collected. All materials possess well-ordered hexagonal mesoporous arrays (1D channels), including the material SBA-15-0 h. The 2D p6mm hexagonal structure was observed as well, especially on those 9 ACS Paragon Plus Environment


Page 10 of 19

materials with more hydrothermal synthesis time (e.g., 18 h and 66 h). The long synthesis time in the SBA-15-66 h material enabled the copolymer to perfectly arrange and the silanol groups to condense slowly. By using a high-dark contrast technique in the TEM images, the distance between the mesoporous arrays was estimated to be 110 Å, in agreement with that determined from the XRD data and in accordance with the observations of Pai et al.25.

Figure 2. TEM images of calcined SBA-15 prepared for 66 h To obtain crystallographic information from the collected materials with the synthesis reaction time, low-angle PXRD was performed, as shown in Figure 3(a). The diffraction patterns for the materials show three well-resolved Bragg peaks at 0.90, 1.5, and 1.7° (2Ɵ), assigned to the (100), (110), and (200) reflection planes, respectively, for a highly ordered 10 ACS Paragon Plus Environment

Page 11 of 19 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


mesoporous material. By qualitative analysis, the low-angle PXRD demonstrates that the structural organization of the mesoporous materials is enhanced by increasing hydrothermal treatment time from 6 h to 66 h. The material synthesized in 66 h presents a higher diffraction pattern for the (100) plane. As observed in the TEM images, the material collected at 0 h has a small diffraction peak at 0.9°, owing to the primary channels, as in the inset of Figure 3(a). This is evidence that the mesoporous material synthesized at 0 h may have considerable porosity. Therefore, N2 adsorption and desorption isotherms were collected at 77 K (Figure 3(b)). All samples exhibited Type IV isotherms with a H1 hysteresis loop26 , indicating that the materials were cage-like mesoporous with cylindrical pore systems, including the one collected at 0 h synthesis time, as previously expected from the TEM and low-angle PXRD results. This porosity observed in the 0 h material can be explained by silanol condensation, which preserves the hexagonal pore structure of SBA-15. Upon subjecting the material to thermal treatment to remove the Pluronic P-123 copolymer, the hexagonal pore structure of the material was preserved. In addition, the hydrothermal synthesis time could modulate the specific surface area and size of the mesoporous material. SBA-15 at 0 h has a specific surface area of 424 ± 1 m2.g-1, as calculated by the Brunauer–Emmett–Teller (BET) method; however, the specific surface area increases with longer hydrothermal synthesis reaction times. SBA-15 at 6 h, 18 h, and 66 h has specific surface areas of 640 ± 4 m2.g-1, 756 ± 4 m2.g-1, and 723 ± 3 m2.g-1, respectively, in good agreement with the literature27-31. The microporous area, total pore volume, and mesoporous volume also increased with the synthesis time, due to the presence of a second wall porosity. In fact, the mesoporous material SBA-15 had a primary mesoporous channel that was separated by walls, but interconnected by microporous channels; therefore, the specific surface area increased. Furthermore, the specific surface area increase with the hydrothermal synthesis time can be explained by the structural organization, which indicates that materials with longer synthesis times are highly organized. Other textural properties of the synthesized materials were a mesoporous size increase with the hydrothermal synthesis reaction time, as displayed in the inset of Figure 3(b). Although SBA-15-0 h has a pore size of 4.0 nm as calculated by the Brunauer-Joyner-Halenda (BJH) method, the most organized material, SBA-15-66 h, exhibited a pore size of 6.4 nm.


(100)

Counts (a.u.)

(110)

0h 0.5

(200)

Counts (a.u.)

Page 12 of 19

1.0

1.5

2.0

2.5

3.0

2() degree

66 h 18 h 6h 0h

1

2

3

4

5

2() degree Figure 3(a). Powder low-angle XRD results of samples prepared for 0, 6, 18, and 66 h. The inset illustrates the low angle for materials obtained for 0 h

600

450

66 h

dV/dlog(D) Pore Volume (cm³/g)

Quantity adsorbed (cm³/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

(100)


66 h

6h

6h

0h

20

300

18 h

18 h

40

60

80

100

120

140

Pore Diameter (Angstrons)

0h

150

0 0.0

0.2

0.4

0.6

0.8

1.0

Relative pressure (P/P0)

Figure 3(b). N2 physisorption isotherms and inset showing pore size distribution curves by the BJH method.

This behavior occurs due to a decrease in the pore wall thickness of the structures with increasing hydrothermal synthesis time (Table 2). Table 2 summarizes the textural and structural properties determined for the synthesized SBA-15 mesoporous materials.


Page 13 of 19 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 2. Textural and structural properties of samples prepared for 0, 6, 18, and 66 h Hydrothermal Synthesis Time Reaction (h)

Textural and Structural Properties d-Spacing d100(nm)

0

6

18

66

10.13

9.68

9.80

9.87

(nm)*

11.70

11.18

11.32

11.40

Pore wall thickness dW (nm)#

7.43

6.95

6.72

6.22

Pore size dP (nm)

3.95

5.14

5.77

6.38

424

640

756

723

Maximum adsorbed amount BET (cm3/g)

292.81

437.32

562.74

605.79

Total pores volume (cm3/g)

0.4529

0.6764

0.8704

0.9370

0.0190

0.1284

0.1557

0.1275

141.51

298.71

360.43

297.86

282.81

341.02

395.86

425.07

0.4510

0.6785

0.8674

0.9328

141.39

93.78

79.33

82.99

Unit cell parameter, a0

Specific surface area BET

Micropore volume t-plot Micropore area t-plot

(m2/g)

(cm3/g)

(m2/g)

External area t-plot (m2/g) Mesoporos Volume BJH

(cm3/g)

Average size of particles (Å) *a

= 2d100/√3 (reference)

#d

a0 - dP (reference)

0

W=

The pore wall thickness was calculated by low-angle PXRD, and the results confirm the pore wall thickness supposition, where SBA-15-0 h had a pore size of 7.43 nm, whereas the SBA-15 sample synthesized for 66 h had a pore size of 6.22 nm. Thus, increase in the size of the mesopores may be attributed to copolymer penetration on the silica matrix wall along with reaction time — in this case, the PO group. To understand the effect of the hydrothermal synthesis reaction time on the structure condensation of SBA-15, FTIR spectra and

29Si-NMR

cross-polarized magic angle spinning

spectra were obtained for these materials before and after thermal treatment. From the FTIR spectra, for the material before thermal treatment at 550°C, the main characteristic is vibration for the signal at 949 cm-1, due to the Si–OH groups present on the spectra for all materials (Figure 4). In addition, the intensity of this peak decreases as the reaction time progresses, implying that the hydrothermal synthesis time affects the structure condensation of the material. Moreover, Si–O–Si (455 cm-1 e 798 cm-1) and Si–O (564 cm-1) exist in the spectra of all materials. A signal for the alkyl C–H stretch is no longer observed in the FTIR spectra of these materials after thermal treatment at 550°C for 6 h, demonstrating the effective removal of the Pluronic P 123 template (Figure S2). The relationship between the chemical groups (Si–OH, Si–O, Si–O–Si) is difficult to understand by only FTIR analysis; this can be achieved by employing a more accurate 13 ACS Paragon Plus Environment


Page 14 of 19

technique, such as 29Si-NMR-CP MAS in the solid state. The 29Si-NMR-CP MAS spectra for these materials after thermal treatment at 550°C show three peaks at 90 ppm, 98 ppm, and 109 ppm, denoted as Q2, Q3, and Q4, respectively (Figure S3). Qualitative analysis of the

29Si-

NMR-CP MAS spectra demonstrates that the ratios between the three chemical groups ([Si(OSi)2(OH)2], [Si(OSi)3OH], [Si(OSi)4]) are the same. Therefore, it is proposed that the mesoporous size modulation arises from a second condensation degree with thermal treatment at 550°C to remove the Pluronic P 123 template. However, the ratios of the chemical groups ([Si(OSi)2(OH)2], [Si(OSi)3OH], [Si(OSi)4]) of the SBA-15 materials are different, implying that the condensation degree with the hydrothermal synthesis time is different for each material. Indeed, the

29Si-NMR-CP

MAS spectra for the

SBA-15 materials before thermal treatment at 550°C (Figure 5) corroborate this. There is a decrease in the Q3 site signal in Figure 5, with the hydrothermal synthesis time. The Q3/Q4 ratios calculated by the peak heights at these sites are 2.43, 2.12, 1.51, and 1.29 for the SAB15 materials collected at 0, 6, 18, and 66 h, respectively (Figure S3). This implies that the SBA-15 material collected at 0 h has more [Si(OSi)3OH] than [Si(OSi)4], and, when this material is subjected to thermal treatment at 550°C, a second condensation degree of the [Si(OSi)3OH] groups to [Si(OSi)4] occurs. Furthermore, once the SAB-15-0 h material has a higher Q3/Q4 ratio, the condensation degree for hydrothermal synthesis is low. This implies a higher condensation degree at 550°C of thermal treatment to remove the templates. This higher condensation degree for SBA-15-0 h at 550°C affects the mesoporous array size, resulting in the smallest mesoporous arrays among all SBA-15 materials collected. Conversely, the SBA-15-66 h material has a higher mesoporous size, because the hydrothermal synthesis time is longer than for the other materials. This implies a high condensation degree during hydrothermal synthesis, resulting in a highly ordered material, but a low second condensation degree for thermal treatment at 550°C.


Si-O Si-O-Si

Si-OH Si-O-Si

3000

Si-O-Si

3500

O-H

CH

66 h

Transmittance (%)

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


O-H

Page 15 of 19

18 h

6h

0h

4000

2500

2000

1500

1000

500

-1

Wavenumber (cm )

Figure 4. FTIR spectra of materials before calcination of the samples prepared for 0, 6, 18, and 66 h.

Figure 5. 29Si- cross polarized MAS NMR spectra of samples prepared for 0, 6, 18, and 66 h.



Page 16 of 19

4.0 Conclusions Optimized silicon extraction by a fusion method considering the effect of the three parameters (temperature, time, and SCBA/NaOH ratio) was performed. This optimized method was evaluated using chemometric tools, by considering the available fusion temperature, fusion time, and NaOH/SCBA ratio. The best time and temperature, 40 min and 550°C, respectively, were determined for alkaline fusion using an NaOH/SCBA ratio of 1.0. In addition, it was demonstrated that waste SCBA is an alternative environmentally friendly source for the preparation of low-cost and green mesoporous silica. The SBA-15 prepared here has all the characteristic properties for a commercial material. Furthermore, it was shown that the textural properties, such as the pore size and specific surface area, may be tuned. This is a consequence of the synthesis time, and the second condensation degree demonstrated by 29Si

solid-state NMR experiments.

Supporting Information RSM experiments, model fitting, FTIR results, particle size distribution curves, SEM images and Q3/Q4 relationship of samples. Factors selected to build 2k factorial design and real and code values, parameter levels of CCRD (coded value) and silicon dissolution values. Acknowledgments The authors acknowledge financial support from CNPQ/Brazil, by processes 310820/2011-1, 428017/2016-2, 113881/2018-5, 314220/2018-6, 434504/2018-1, 168778/2017-3, and 577527/2008-8,

CAPES/Brazil,

Fundação

Araucária-PR

(process:

830/2013)

and

COMCAP/UEM by analysis. References 1. Balakrishnan, M.; Batra, V. S., Valorization of solid waste in sugar factories with possible applications in India: A review. Journal of Environmental Management 2011, 92, (11), 2886-2891. 2. Eykelbosh, A. J.; Johnson, M. S.; Couto, E. G., Biochar decreases dissolved organic carbon but not nitrate leaching in relation to vinasse application in a Brazilian sugarcane soil. Journal of Environmental Management 2015, 149, 9-16. 3. Teixeira, S. R.; Souza, A. E. D.; Santos, G. T. D. A.; Peña, A. F. V.; Miguel, Á. G., Sugarcane Bagasse Ash as a Potential Quartz Replacement in Red Ceramic. Journal of the American Ceramic Society 2008, 91, (6), 1883-1887. 4. Fagnani, E.; Guimarães, J. R., Waste management plan for higher education institutions in developing countries: The Continuous Improvement Cycle model. Journal of Cleaner Production 2017, 147, 108-118. 16 ACS Paragon Plus Environment

Page 17 of 19 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


5. Paglietti, F.; Malinconico, S.; della Staffa, B. C.; Bellagamba, S.; De Simone, P., Classification and management of asbestos-containing waste: European legislation and the Italian experience. Waste Management 2016, 50, 130-150. 6. Xu, L.; Zhang, X.; Ling, M., Spillover effects of household waste separation policy on electricity consumption: Evidence from Hangzhou, China. Resources, Conservation and Recycling 2018, 129, 219-231. 7. Purnomo, C. W.; Salim, C.; Hinode, H., Synthesis of pure Na–X and Na–A zeolite from bagasse fly ash. Microporous and Mesoporous Materials 2012, 162, 6-13. 8. Shigemoto, N.; Hayashi, H.; Miyaura, K., Selective formation of Na-X zeolite from coal fly ash by fusion with sodium hydroxide prior to hydrothermal reaction. Journal of Materials Science 1993, 28, (17), 4781-4786. 9. Tanaka, H.; Fujii, A., Effect of stirring on the dissolution of coal fly ash and synthesis of pureform Na-A and -X zeolites by two-step process. Advanced Powder Technology 2009, 20, (5), 473-479. 10. Chareonpanich, M.; Namto, T.; Kongkachuichay, P.; Limtrakul, J., Synthesis of ZSM-5 zeolite from lignite fly ash and rice husk ash. Fuel Processing Technology 2004, 85, (15), 1623-1634. 11. Inada, M.; Tsujimoto, H.; Eguchi, Y.; Enomoto, N.; Hojo, J., Microwave-assisted zeolite synthesis from coal fly ash in hydrothermal process. Fuel 2005, 84, (12), 1482-1486. 12. Hollman, G. G.; Steenbruggen, G.; Janssen-Jurkovičová, M., A two-step process for the synthesis of zeolites from coal fly ash. Fuel 1999, 78, (10), 1225-1230. 13. Querol, X.; Umaña, J. C.; Plana, F.; Alastuey, A.; Lopez-Soler, A.; Medinaceli, A.; Valero, A.; Domingo, M. J.; Garcia-Rojo, E., Synthesis of zeolites from fly ash at pilot plant scale. Examples of potential applications. Fuel 2001, 80, (6), 857-865. 14. Moisés, M. P.; da Silva, C. T. P.; Meneguin, J. G.; Girotto, E. M.; Radovanovic, E., Synthesis of zeolite NaA from sugarcane bagasse ash. Materials Letters 2013, 108, 243-246. 15. Boza, A. F.; Kupfer, V. L.; Oliveira, A. R.; Radovanovic, E.; Rinaldi, A. W.; Meneguin, J. G.; Domingues, N. L. C.; Moises, M. P.; Favaro, S. L., Synthesis of [small alpha]-aminophosphonates using a mesoporous silica catalyst produced from sugarcane bagasse ash. RSC Advances 2016, 6, (29), 23981-23986. 16. Moisés, M. P.; de Almeida, P. P.; da Silva, C. T. P.; Rinaldi, A. W.; Girotto, E. M.; Meneguin, J. G.; Arroyo, P. A.; Bazan, R. E.; Fávaro, S. L.; Radovanovic, E., Synthesis of zeolite from multilayer food packing and sugar cane bagasse ash for CO2 adsorption. RSC Advances 2014, 4, (89), 4857648581. 17. Bezerra, M. A.; Santelli, R. E.; Oliveira, E. P.; Villar, L. S.; Escaleira, L. A., Response surface methodology (RSM) as a tool for optimization in analytical chemistry. Talanta 2008, 76, (5), 965-977. 18. Zhao, D.; Feng, J.; Huo, Q.; Melosh, N.; Fredrickson, G. H.; Chmelka, B. F.; Stucky, G. D., Triblock Copolymer Syntheses of Mesoporous Silica with Periodic 50 to 300 Angstrom Pores. Science 1998, 279, (5350), 548-552. 19. Attard, G. S.; Glyde, J. C.; Göltner, C. G., Liquid-crystalline phases as templates for the synthesis of mesoporous silica. Nature 1995, 378, 366. 20. Corma, A., From Microporous to Mesoporous Molecular Sieve Materials and Their Use in Catalysis. Chemical Reviews 1997, 97, (6), 2373-2420. 21. Davis, M. E., Ordered porous materials for emerging applications. Nature 2002, 417, 813. 22. Monnier, A.; Schüth, F.; Huo, Q.; Kumar, D.; Margolese, D.; Maxwell, R. S.; Stucky, G. D.; Krishnamurty, M.; Petroff, P.; Firouzi, A.; Janicke, M.; Chmelka, B. F., Cooperative Formation of Inorganic-Organic Interfaces in the Synthesis of Silicate Mesostructures. Science 1993, 261, (5126), 1299-1303. 23. Zhao, J.; Gao, F.; Fu, Y.; Jin, W.; Yang, P.; Zhao, D., Biomolecule separation using large pore mesoporous SBA-15 as a substrate in high performance liquid chromatography. Chemical Communications 2002, (7), 752-753. 24. Bacariza, M. C.; Graça, I.; Bebiano, S. S.; Lopes, J. M.; Henriques, C., Micro- and mesoporous supports for CO2 methanation catalysts: A comparison between SBA-15, MCM-41 and USY zeolite. Chemical Engineering Science 2018, 175, 72-83.



Page 18 of 19

25. Pai, R. A.; Humayun, R.; Schulberg, M. T.; Sengupta, A.; Sun, J.-N.; Watkins, J. J., Mesoporous Silicates Prepared Using Preorganized Templates in Supercritical Fluids. Science 2004, 303, (5657), 507-510. 26. Thommes, M.; Kaneko, K.; Neimark Alexander, V.; Olivier James, P.; Rodriguez-Reinoso, F.; Rouquerol, J.; Sing Kenneth, S. W., Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report). In Pure and Applied Chemistry, 2015; Vol. 87, p 1051. 27. Ghorbani-Vaghei, R.; Hemmati, S.; Veisi, H., Pd immobilized on amidoxime-functionalized Mesoporous SBA-15: A novel and highly active heterogeneous catalyst for Suzuki–Miyaura coupling reactions. Journal of Molecular Catalysis A: Chemical 2014, 393, 240-247. 28. Kim, Y.; Bae, J.; Park, J.; Suh, J.; Lee, S.; Park, H.; Choi, H., Removal of 12 selected pharmaceuticals by granular mesoporous silica SBA-15 in aqueous phase. Chemical Engineering Journal 2014, 256, 475-485. 29. Wan, M. M.; Sun, X. D.; Liu, S.; Ma, J.; Zhu, J. H., Versatile drug releaser derived from the Ti-substituted mesoporous silica SBA-15. Microporous and Mesoporous Materials 2014, 199, 40-49. 30. Rajabi, F.; Fayyaz, F.; Luque, R., Cytosine-functionalized SBA-15 mesoporous nanomaterials: Synthesis, characterization and catalytic applications. Microporous and Mesoporous Materials 2017, 253, 64-70. 31. Park, D.; Kim, J.; Kim, T., Nonthermal plasma-assisted direct conversion of methane over NiO and MgO catalysts supported on SBA-15. Catalysis Today 2018, 299, 86-92.


Page 19 of 19 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


For Table of contents use only An optimized process for recycling silicon chemical compounds from agroindustry solid waste

Joziane Gimenes Meneguin, Paulo Henrique Galves Bruns, Cleiser Thiago Pereira da Silva, Murilo Pereira Moisés, Marcos Rogério Guilherme, Eduardo Radovanovic, Andrelson Wellington Rinaldi*

Optimized silicon extraction by a fusion method considering the effect of the three parameters (temperature, time, and SCBA/NaOH ratio) was performed.


An Optimized Process for Recycling Silicon Chemical Compounds

Recommend Documents