Chem.
A similar trend can be observed for other raw and aminated biochars samples too. Eng. Technol. The figures also indicated that the volume adsorbed is higher for biochar samples synthesized at high temperature. (2019a). For instance, the shape of the above described isotherms are similar to Type I isotherms (as per IUPAC classification) which are common for microporous solids (Brunauer et al., 1940). Influence of pyrolysis temperature and holding time on properties of biochar derived from medicinal herb (radix isatidis) residue and its effect on soil CO2 emission. Vyas, A., Chellappa, T., and Goldfarb, J. L. (2017). Consistent with these observations, the C content of agro-industrial-based biochars (CS and SB) increased with temperature and also with respect to the %C content of their corresponding raw chars. doi: 10.1021/ie8006984, Lee, Y., Park, J., Ryu, C., Gang, K. S., Yang, W., Park, Y.-K., et al. Ultrason. (2017).
However, further increasing the pyrolysis temperature to 800C reduced the adsorption capacity values by 7076% compared to 700C.
J. Therm. This could be due to the reduction in surface area at elevated temperature (800C) caused by the destruction of surface porosity, in addition to the reduction in %N contents at 800C (Tables 2, 3). This is due to largely exposed facets of the crystal lattice that show a few peaks with high relative intensity (Zhang et al., 2020). Encyclopedia of analytical chemistry: applications, theory and instrumentation in Interpretation of Infrared Spectra, a Practical Approach, ed R. A. Meyers (Newtown: John Wiley and Sons). Vizzini, G., Bardi, A., Biagini, E., Falcitelli, M., and Tognotti, L. (2008). 60, 10541065.
As expected, the %N content of the activated biochar significantly increased, in the range of 26 times in MS and 1.62.6 times in SG samples, compared to the corresponding raw chars, since the aminated chars incorporated N-containing TEPA. Increasing temperature showed increasing trend of intensity ratios and more defects in forms of functionality which is also observed in IR spectra of aminated samples for A-MS-500, A-MS-600, and A-MS-700.
Fuel 85, 22022212. Figure 6. Energies 5, 49525001. This peak comes from the formation and successive ordering of aromatic carbon (Paris et al., 2005) indicating crystallization (Tushar et al., 2012). Technol. Fuel 235, 14751491. Environ. VR: conducting SEM analysis. Front. J. Anal. Evaluation of various types of Al-MCM-41 materials as catalysts in biomass pyrolysis for the production of bio-fuels and chemicals. As observed from Figure 9, the sono-aminated chars have much higher adsorption capacities (almost 3 times) those of raw chars. doi: 10.1016/j.biortech.2012.12.165, Amini, E., Safdari, M.-S., Deyoung, J. T., Weise, D. R., and Fletcher, T. H. (2019). Sci. (2012). The total weight loss for these samples can be listed as 26.7, 13.9, 11.8, and 9.5%, respectively for US-Am-MS 500, US-Am-MS 600, US-Am-MS 700 and US-Am-MS 800, respectively. Based on the above discussion it can be suggested that herbaceous biochars showed greater variations in elemental compositions compared to agro-industrial chars for the pyrolysis temperature range of 500800C. Chem. Copyright 2020 Chatterjee, Sajjadi, Chen, Mattern, Hammer, Raman and Dorris. The two agro-industrial-based biochars (CS and SB) showed similar trends. As observed from the figures biochars began to increase aromatic deformation at higher pyrolysis temperature particularly at 800C. (2013). Technol. Appl. NH and AD: conducting Raman analysis. Characterization of biochar of pine pellet. This can be explained as a result of changes of both numerator and denominator for H/C and O/C ratios, making the entire ratio almost equal. doi: 10.1007/s10973007-8493-x, Popp, J., Lakner, Z., Harangi-Rakos, M., and Fari, M. (2014). doi: 10.1039/D0RA00769B, Zhao, S.-X., Ta, N., and Wang, X.-D. (2017). Calorim.
J. Agric. J. Anal. Mechanisms of metal sorption by biochars: biochar characteristics and modifications. The ultrasonic-amine functionalized spectra show shifts in peaks due to interaction between surface functional groups and amino groups and the subsequent amine attachment. The above mentioned weight loss can be attributed to the degradation and decomposition of organic materials (Sun et al., 2014). The biochars underwent two-step sonochemical activation: low-frequency low-temperature ultrasound activation followed by TEPA functionalization. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. Nitrogen functionalized biochar as a renewable adsorbent for efficient CO2 removal. Effect of pyrolysis temperature on miscanthus (Miscanthus giganteus) biochar physical, chemical and functional properties. Removal of ash from the biochar structure could be attributed to the washing away of mineral contents of the biochars during aqueous modifications (Kim W. K. et al., 2013). Sust. Effects of pyrolysis temperature on soybean stover-and peanut shell-derived biochar properties and TCE adsorption in water.
As a result of the addition of disordered functional groups, the ID/IG intensity ratio is expected to be greater for sono-aminated chars compared with raw samples. Although %N content decreased with temperature, the carbon content increased significantly, thus facilitating the increase in adsorption capacities. For instance, CS and SB exhibited a significant increase in surface area (96284 and 83221 m2/g for CS and SB, respectively) and pore volumes (0.050.14 and 0.050.11 cc/g) upon increasing the temperature from 500 to 600C.
in biochar samples with temperature since these elements are not lost by volatilization (Zhou et al., 2013). doi: 10.1371/journal.pone.0156894, Sadaka, S., Sharara, M., Ashworth, A., Keyser, P., Allen, F., and Wright, A. Rapid pyrolysis of agricultural residues at high temperature. The activated samples did not show any significant change in H/C and O/C ratios compared to the raw samples, despite substantial differences for C or O (Table 3) in sono-aminated vs. raw chars for some samples (MS600, SG600, SB600, and SB800 for %C; SB700 for % O). (2016). Bioresour. Characterization of cadmium removal from aqueous solution by biochar produced from a giant miscanthus at different pyrolytic temperatures. 10, 55855589. (2007). Sust. These values are 215251, 287309, 285310, and 227259% higher compared to those of the raw biochar at the temperatures of 500, 600, 700, and 800C, respectively. Yet, the aminated MS, particularly at 600 and 700C, represented the maximum CO2 adsorption.
(2006). In terms of temperature effects, the maximum of N content was observed in the lower temperatures (600C for MS and 500C for SG), the N content was reduced for middle-ranged temperatures (600 or 700C) and enhanced by further increase of temperature (to 800C). Characterization of biochar from switchgrass carbonization. doi: 10.1002/ep.12783, Paris, O., Zollfrank, C., and Zickler, G. A. Sonochem. Similarly, For US-SG 700, SEM image (Figure 2B) depicts that acoustic treatment slightly affected the structures. Technol. Figures 6AD show the Raman spectra of all raw and activated biochar samples synthesized under different temperature ranges- 500, 600, 700, and 800C. Int. (2019b). Above 600C, decomposition for all the biochars completed and the curves became stable. (2014). The intensity ratio values as observed from Table S1 exhibited the highest increment for 600700C corresponding to their maximum adsorption capacity. Energies 10:1293. doi: 10.3390/en10091293, Zhao, Y., Zhang, R., Liu, H., Li, M., Chen, T., Chen, D., et al. 122, 2132. In addition, the changes of N content were more prominent in herbaceous chars compared with agro-industrial-based biochars. 148, 196201. Science 325, 16471652. As observed, the ash content even increased with temperature. Sci. Effects of feedstock and pyrolysis temperature on biochar adsorption of ammonium and nitrate. Identification of preferentially exposed crystal facets by X-ray diffraction. Similar to MS, pyrolysis temperature caused increment of (ash-excluded) %C contents from 76 to 91% in raw SG chars to 7788% in activated chars. Received: 29 January 2020; Accepted: 24 April 2020; Published: 28 May 2020. (2015).
This trend is similar to what is reported in the literature for MS (Suliman et al., 2016; Zhao et al., 2017) and SG (Zanzi et al., 2002; Cetin et al., 2005; Guerrero et al., 2005). Fuel 235, 11311145. (2005). It must also be highlighted that the activating treatments of the biochars were conducted near room temperature, making the sonication and amination activation processes notably energy efficient, compared to thermal activation. 176, 288291. The enhancement of surface area and pore volumes was caused by the degradation of the organic materials (hemicelluloses, cellulose, and lignin) and the formation of vascular bundles or channel structures during pyrolysis (Kim W. K. et al., 2013; Li et al., 2013). PLoS ONE 9:e113888. The peak around 1,026 cm1 is attributed to C-O stretching vibrations or the C-N stretch of an aliphatic primary amine (Coates, 2006). Sorption of heavy metals on chitosan-modified biochars and its biological effects. Biofuels production through biomass pyrolysisa technological review. doi: 10.1016/j.jenvman.2010.09.008, Imam, T., and Capareda, S. (2012). Int. doi: 10.1016/j.jtice.2016.02.012, Gai, X., Wang, H., Liu, J., Zhai, L., Liu, S., Ren, T., et al. This leads to the generation of porosity more in the agro-industrial residues (CS and SB) than herbaceous residues (MS and SG). Similar observations are found in the literature and in our previous studies (Stankovich et al., 2006; Chen et al., 2014; Chatterjee et al., 2018, 2019; Sajjadi et al., 2019a). Similar to CS, it generally showed increased %C and ash content, and reduced H/C-O/C ratios and %N content, for the temperature range of 500800C, although values at 700C were often the most extreme. doi: 10.1039/C7GC03457A, Mia, S., Dijkstra, F. A., and Singh, B. Influence of pyrolysis temperature and heating rate on the production of bio-oil and char from safflower seed by pyrolysis, using a well-swept fixed-bed reactor. It is worth noting that the micro surface area of all biochars increased by almost 200 m2/g (on average) with a pyrolysis temperature increase of 500 to 700C. Effect of pyrolysis pressure and heating rate on radiata pine char structure and apparent gasification reactivity. FTIR spectra of raw and activated samples (A) miscanthus, (B) switchgrass, (C) corn stover, and (D) sugarcane bagasse synthesized at different pyrolysis temperatures. This further indicates the decrease of aliphatic hydrocarbon and development of aromatic structure of biochar with increasing pyrolysis temperature (Major et al., 2018) as found from elemental analysis results that showed increased %C content at elevated temperature (Table 3 and Table S1). BS: idea of the work, interpretation of results, and writing the manuscript. Various other support from the University of Mississippi is also gratefully acknowledged. The sonicated samples also showed significant increases in surface area (323 to 520 m2/g for MS, from 309 to 486 m2/g for SG, from 215 to 399 m2/g for CS, and 192332 m2/g for SB) with increasing the pyrolysis temperature from 500 to 600C. 35, 777815. Similar behavior was observed in the two agro-industrial-based biochars (CS and SB). (2015). ACS Sust. All the raw samples demonstrated a slight increase (413%) in CO2 capture capacity at 700C compared with 600C, which can be substantiated as per the elemental analysis data (C and N contents) (Table 3). J. Agric. *Correspondence: Baharak Sajjadi, bsajjadi@olemiss.edu, Biochar Modification Technologies for Sustainable Water, Energy and Food Nexus, View all 47, 74197423. The mass loss occurred slowly around 6070C, which is associated with the loss of the initial moisture of the raw sample observed in Figure 7A (Santos et al., 2015). doi: 10.1021/jf501139f, Cetin, E., Gupta, R., and Moghtaderi, B. This is mostly attributed to the further degradation of lignin and the reaction of aromatic condensation (Chen et al., 2012), which increases the release of volatile matter and creates more pores. All raw biochars exhibited a gradual increase in adsorption capacity in the range of 6788% while increasing the temperature from 500 to 600C. (2017). Distinguishing primary and secondary reactions of cellulose pyrolysis. doi: 10.1021/ef3018783, Li, H., Dong, X., Da Silva, E. B., De Oliveira, L. M., Chen, Y., and Ma, L. Q. Additionally, surface area and pore volumes were also enhanced at elevated temperatures up to 700C. Physicochemical characterization of miscanthus and its application in heavy metals removal from wastewaters. Figure 4. The spectra exhibit two prominent peaks at 1,400 and 1,600 cm1 designated as D and G peaks. Am. This trend can be correlated to Tables 2, 3 that showed significant changes in surface areas and elemental compositions, respectively, when pyrolysis temperature was increased from 500 to 600C, irrespective of the biochar type. Res. The plots correspond to the volume of adsorbed gas with respect to the relative pressure, indicating adsorption ability of the chars.
Pyrolysis 110, 277284. This trend is also corroborated based on Raman analysis. Lee et al. The XRD diffraction patterns were taken in the 2 range of 1080 for raw and ultrasound amine activated of miscanthus biochars synthesized at 500, 600, 700, and 800C. Table 2. doi: 10.1016/j.jaap.2014.09.016, Zambon, I., Colosimo, F., Monarca, D., Cecchini, M., Gallucci, F., Proto, A., et al. A-CS 600, A-CS-700, A-CS 800 exhibited stronger C-N peak over R-CS 600, R-CS 700, and R-CS 800. doi: 10.1016/j.biombioe.2014.01.004, Nwajiaku, I. M., Olanrewaju, J. S., Sato, K., Tokunari, T., Kitano, S., and Masunaga, T. (2018). But a further increase in pyrolysis temperature (to 800C) resulted in a reduction in %C content and similarly follows a reverse trend for other elemental constituents. Energy Fuels 27, 942953. Fuel 84, 13281334. Raman spectroscopy combines a prominent surface selectivity and an exceptional sensitivity to the degree of structural order (Ashworth et al., 2014).
51, 83598367. Adsorption capacities of raw and sono-aminated biochars synthesized under different temperature conditions are presented in Figure 9. This trend is further verified from the following physicochemical characterizations data. In addition, the most notable change in the ID/IG intensity ratio of both herbaceous and agro-industrial chars was observed when the temperature was raised from 500 to 600C followed by a slight increment from 600 to 800C. The results of the present study also generally exhibited enhancement of ash content with pyrolysis temperature, mainly due to the increase in the concentration of minerals (such as Na, Mg, Ca, K, etc.) The plots correspond to the volume of adsorbed gas with respect to the relative pressure, indicating adsorption ability of the chars. 88, 523531. doi: 10.1016/j.rser.2014.01.056, Rafiq, M. K., Bachmann, R. T., Rafiq, M. T., Shang, Z., Joseph, S., and Long, R. (2016). doi: 10.1016/j.jaap.2004.12.008, Guittonneau, F., Abdelouas, A., Grambow, B., and Huclier, S. (2010). 7, 269276. Increasing pyrolysis temperature had a significant effect on the elemental constituents and H/C (the degree of aromaticity) (Al-Wabel et al., 2013) and O/C (the degree of polarity) ratios (Mimmo et al., 2014) of raw biochars. Clean. (2016). (2019). In order to prevent misinterpretation concerning organic content, elemental analysis of aminated samples is discussed by eliminating the impact of ash alteration. Green preparation of magnetic biochar for the effective accumulation of Pb(II): performance and mechanism. As found from Table 2, upon sonication the microporous surface area and pore volumes for all the biochars increased. Effect of feedstock and pyrolysis temperature on properties of biochar governing end use efficacy.
CO2 adsorption capacities of both raw and sono-chemically activated biochar samples synthesized at different pyrolysis temperatures. indicates a more hydrophobic structure (Peterson et al., 2013). Although the pyrolysis temperature showed a slight effect on adsorption capacity of the raw biochars, it demonstrated a significant interaction with the acoustic-based amination process and the subsequent adsorption capacity of activated biochars. Pyrolysis 124, 7988. RC: conducting the experiments, interpretation of results, and writing the manuscript. For instance, elemental analysis results (Table 3) expressed intense %N contents for aminated biochars at 600C. The maximum values were observed for MS, ranging from 0.78 to 0.96 for 500 to 800C, respectively, consistent with their surface area data (Table 2). Similarly, A-SG 600 and A-SG-700 showed improved amination than R-SG 600 and R-SG 700. It is considered to be one of the most informative methods for investigation of the structural perfection of carbonaceous material (such as biochar). Appl. (2016). PLoS ONE 11:e0156894. Comparison of biochar properties from biomass residues produced by slow pyrolysis at 500C. doi: 10.1016/j.biombioe.2017.06.024, Zhang, J., Liu, J., and Liu, R. (2015). For each experimental run, a biochar sample of 2 g was put inside the tube and heated under helium (99.99%) gas flow (500 cm3 min1) at 378 K for 1 h to remove moistures from the adsorbent. 26, 390397. 62, 37913799. 9, 246253. Most of the biochars showed intensified peak at 1,4001,600 cm1 attributed to aromatic C=C stretching except for MS. Variables governing the initial stages of the synergisms of ultrasonic treatment of biochar in water with dissolved CO2. It can be concluded that elevated pyrolysis temperature showed overall reduction in elemental %N contents of both raw and aminated chars (Table S1), though a sudden jump in N content of almost all samples was observed at 800C. doi: 10.1021/sc300098e, Plaza, M., Pevida, C., Arias, B., Fermoso, J., Arenillas, A., Rubiera, F., et al. Brewer, C. E. (2012). Pyrolysis temperature induced changes in characteristics and chemical composition of biochar produced from conocarpus wastes.
Based on Figure 9, adsorption capacities for activated chars can be categorized as: 0.861.23, 2.152.53, 2.222.89, and 1.341.74 mmol/g for the temperature ranges of 500, 600, 700, and 800C, respectively. Carbon 43, 5366. Total Environ. (2018). Appl. The lower the ID/IG ratio, the higher the degree of graphitization of the carbonaceous structure. Biomass Bioenergy 37, 97105. This furthermore proves that the lower temperature derived biochars were less thermally stable than the higher temperature derived ones, probably because they were not fully carbonized (Sun et al., 2014; Zhao et al., 2017). Ultrason. 118, 536544. The increase in carbon content at higher temperature reflects the increasing degree of carbonization (Zhou et al., 2013) and the decrease in H and O contents is likely due to dehydration reactions, the decomposition of the oxygenated bonds, and the release of low molecular weight byproducts containing H and O. As observed, raw MS shows maximum adsorption capacities in comparison to all other raw chars (MS>SG>CS>SB) under all temperature ranges, although the differences are small.
Additionally, the effectiveness of the developed activation technique has been assessed based on the comparison of the adsorption capacities of the sorbent materials from the present study with the literature data and presented in Table S3. doi: 10.1016/j.fuel.2018.08.112, Antonakou, E., Lappas, A., Nilsen, M. H., Bouzga, A., and Stcker, M. (2006). Bioresour. Energies 7, 548567. SG also exhibit similar behavior where %C content showed gradual increment and %N content showed gradual reducing trend with temperature but C-N peak from IR showed improved intensity for aminated samples at 600 and 700C than raw SG under same temperatures. A., and Redwine, C. W. (2014). Images obtained revealed two main morphological features for all biochar samples: fiber structures and pith. doi: 10.1016/j.still.2015.10.002, Liu, Y., He, Z., and Uchimiya, M. (2015). Fundamental and molecular composition characteristics of biochars produced from sugarcane and rice crop residues and by-products. Energy 37, 10581067. doi: 10.1007/s40093018-0213-y, Onay, O. Ind. Biochar Characterization and Engineering Ames, IA. Elemental compositions (dry basis) of raw and activated biochar samples synthesized at different pyrolysis temperatures. This facility was supported in part by grant 1726880, National Science Foundation. Table S1 (organic analysis) depicts gradual increment in %C contents of aminated MS samples with temperature, which is consistent to what was obtained for raw chars. Figure 5. A., and Ashwath, N. (2012). These morphological observations were further substantiated based on the surface area analysis data using BET technique as described in the subsequent section. These intermediate temperatures are clearly the pyrolysis temperatures of choice for maximizing adsorption capacity. Pyrolysis 74, 307314. A., and Jaroniec, M. (2020). The peak at 1,600 cm1 is ascribed to carboxylate (COO-) and 1 amine N-H bending, (Liu et al., 2015) and aromatic C=C stretch is ~1,400 cm1 (Zhao et al., 2017). 8:85. doi: 10.3389/fenrg.2020.00085. Renew. J. Environ. Characterization of bio-oil, syn-gas and bio-char from switchgrass pyrolysis at various temperatures. doi: 10.1016/j.jaap.2011.11.010, Inyang, M., Gao, B., Pullammanappallil, P., Ding, W., and Zimmerman, A. R. (2010). Application of thermogravimetric analysis to the evaluation of aminated solid sorbents for CO2 capture. Chem. The production of engineered biochars in a vertical auger pyrolysis reactor for carbon sequestration. min1) at a heating rate of 5C min1, from 21 to 700C.
Biomass-based pyrolytic polygeneration system on cotton stalk pyrolysis: influence of temperature. 20, 22692278. Effects of feedstock type and pyrolysis temperature on potential applications of biochar. The surface area of the samples can be further justified based on the adsorption isotherm plots as observed in the Figures S2, S3.
An innovative agro-forestry supply chain for residual biomass: physicochemical characterisation of biochar from olive and hazelnut pellets.
In addition to that, all samples exhibit fracture and cracks attributed to release of volatile matters during pyrolysis.
A similar trend can be observed for other raw and aminated biochars samples too. Eng. Technol. The figures also indicated that the volume adsorbed is higher for biochar samples synthesized at high temperature. (2019a). For instance, the shape of the above described isotherms are similar to Type I isotherms (as per IUPAC classification) which are common for microporous solids (Brunauer et al., 1940). Influence of pyrolysis temperature and holding time on properties of biochar derived from medicinal herb (radix isatidis) residue and its effect on soil CO2 emission. Vyas, A., Chellappa, T., and Goldfarb, J. L. (2017). Consistent with these observations, the C content of agro-industrial-based biochars (CS and SB) increased with temperature and also with respect to the %C content of their corresponding raw chars. doi: 10.1021/ie8006984, Lee, Y., Park, J., Ryu, C., Gang, K. S., Yang, W., Park, Y.-K., et al. Ultrason. (2017).
However, further increasing the pyrolysis temperature to 800C reduced the adsorption capacity values by 7076% compared to 700C.
J. Therm. This could be due to the reduction in surface area at elevated temperature (800C) caused by the destruction of surface porosity, in addition to the reduction in %N contents at 800C (Tables 2, 3). This is due to largely exposed facets of the crystal lattice that show a few peaks with high relative intensity (Zhang et al., 2020). Encyclopedia of analytical chemistry: applications, theory and instrumentation in Interpretation of Infrared Spectra, a Practical Approach, ed R. A. Meyers (Newtown: John Wiley and Sons). Vizzini, G., Bardi, A., Biagini, E., Falcitelli, M., and Tognotti, L. (2008). 60, 10541065.
As expected, the %N content of the activated biochar significantly increased, in the range of 26 times in MS and 1.62.6 times in SG samples, compared to the corresponding raw chars, since the aminated chars incorporated N-containing TEPA. Increasing temperature showed increasing trend of intensity ratios and more defects in forms of functionality which is also observed in IR spectra of aminated samples for A-MS-500, A-MS-600, and A-MS-700.
Fuel 85, 22022212. Figure 6. Energies 5, 49525001. This peak comes from the formation and successive ordering of aromatic carbon (Paris et al., 2005) indicating crystallization (Tushar et al., 2012). Technol. Fuel 235, 14751491. Environ. VR: conducting SEM analysis. Front. J. Anal. Evaluation of various types of Al-MCM-41 materials as catalysts in biomass pyrolysis for the production of bio-fuels and chemicals. As observed from Figure 9, the sono-aminated chars have much higher adsorption capacities (almost 3 times) those of raw chars. doi: 10.1016/j.biortech.2012.12.165, Amini, E., Safdari, M.-S., Deyoung, J. T., Weise, D. R., and Fletcher, T. H. (2019). Sci. (2012). The total weight loss for these samples can be listed as 26.7, 13.9, 11.8, and 9.5%, respectively for US-Am-MS 500, US-Am-MS 600, US-Am-MS 700 and US-Am-MS 800, respectively. Based on the above discussion it can be suggested that herbaceous biochars showed greater variations in elemental compositions compared to agro-industrial chars for the pyrolysis temperature range of 500800C. Chem. Copyright 2020 Chatterjee, Sajjadi, Chen, Mattern, Hammer, Raman and Dorris. The two agro-industrial-based biochars (CS and SB) showed similar trends. As observed from the figures biochars began to increase aromatic deformation at higher pyrolysis temperature particularly at 800C. (2013). Technol. Appl. NH and AD: conducting Raman analysis. Characterization of biochar of pine pellet. This can be explained as a result of changes of both numerator and denominator for H/C and O/C ratios, making the entire ratio almost equal. doi: 10.1007/s10973007-8493-x, Popp, J., Lakner, Z., Harangi-Rakos, M., and Fari, M. (2014). doi: 10.1039/D0RA00769B, Zhao, S.-X., Ta, N., and Wang, X.-D. (2017). Calorim.
J. Agric. J. Anal. Mechanisms of metal sorption by biochars: biochar characteristics and modifications. The ultrasonic-amine functionalized spectra show shifts in peaks due to interaction between surface functional groups and amino groups and the subsequent amine attachment. The above mentioned weight loss can be attributed to the degradation and decomposition of organic materials (Sun et al., 2014). The biochars underwent two-step sonochemical activation: low-frequency low-temperature ultrasound activation followed by TEPA functionalization. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. Nitrogen functionalized biochar as a renewable adsorbent for efficient CO2 removal. Effect of pyrolysis temperature on miscanthus (Miscanthus giganteus) biochar physical, chemical and functional properties. Removal of ash from the biochar structure could be attributed to the washing away of mineral contents of the biochars during aqueous modifications (Kim W. K. et al., 2013). Sust. Effects of pyrolysis temperature on soybean stover-and peanut shell-derived biochar properties and TCE adsorption in water.
As a result of the addition of disordered functional groups, the ID/IG intensity ratio is expected to be greater for sono-aminated chars compared with raw samples. Although %N content decreased with temperature, the carbon content increased significantly, thus facilitating the increase in adsorption capacities. For instance, CS and SB exhibited a significant increase in surface area (96284 and 83221 m2/g for CS and SB, respectively) and pore volumes (0.050.14 and 0.050.11 cc/g) upon increasing the temperature from 500 to 600C.
in biochar samples with temperature since these elements are not lost by volatilization (Zhou et al., 2013). doi: 10.1371/journal.pone.0156894, Sadaka, S., Sharara, M., Ashworth, A., Keyser, P., Allen, F., and Wright, A. Rapid pyrolysis of agricultural residues at high temperature. The activated samples did not show any significant change in H/C and O/C ratios compared to the raw samples, despite substantial differences for C or O (Table 3) in sono-aminated vs. raw chars for some samples (MS600, SG600, SB600, and SB800 for %C; SB700 for % O). (2016). Bioresour. Characterization of cadmium removal from aqueous solution by biochar produced from a giant miscanthus at different pyrolytic temperatures. 10, 55855589. (2007). Sust. These values are 215251, 287309, 285310, and 227259% higher compared to those of the raw biochar at the temperatures of 500, 600, 700, and 800C, respectively. Yet, the aminated MS, particularly at 600 and 700C, represented the maximum CO2 adsorption.
(2006). In terms of temperature effects, the maximum of N content was observed in the lower temperatures (600C for MS and 500C for SG), the N content was reduced for middle-ranged temperatures (600 or 700C) and enhanced by further increase of temperature (to 800C). Characterization of biochar from switchgrass carbonization. doi: 10.1002/ep.12783, Paris, O., Zollfrank, C., and Zickler, G. A. Sonochem. Similarly, For US-SG 700, SEM image (Figure 2B) depicts that acoustic treatment slightly affected the structures. Technol. Figures 6AD show the Raman spectra of all raw and activated biochar samples synthesized under different temperature ranges- 500, 600, 700, and 800C. Int. (2019b). Above 600C, decomposition for all the biochars completed and the curves became stable. (2014). The intensity ratio values as observed from Table S1 exhibited the highest increment for 600700C corresponding to their maximum adsorption capacity. Energies 10:1293. doi: 10.3390/en10091293, Zhao, Y., Zhang, R., Liu, H., Li, M., Chen, T., Chen, D., et al. 122, 2132. In addition, the changes of N content were more prominent in herbaceous chars compared with agro-industrial-based biochars. 148, 196201. Science 325, 16471652. As observed, the ash content even increased with temperature. Sci. Effects of feedstock and pyrolysis temperature on biochar adsorption of ammonium and nitrate. Identification of preferentially exposed crystal facets by X-ray diffraction. Similar to MS, pyrolysis temperature caused increment of (ash-excluded) %C contents from 76 to 91% in raw SG chars to 7788% in activated chars. Received: 29 January 2020; Accepted: 24 April 2020; Published: 28 May 2020. (2015).
This trend is similar to what is reported in the literature for MS (Suliman et al., 2016; Zhao et al., 2017) and SG (Zanzi et al., 2002; Cetin et al., 2005; Guerrero et al., 2005). Fuel 235, 11311145. (2005). It must also be highlighted that the activating treatments of the biochars were conducted near room temperature, making the sonication and amination activation processes notably energy efficient, compared to thermal activation. 176, 288291. The enhancement of surface area and pore volumes was caused by the degradation of the organic materials (hemicelluloses, cellulose, and lignin) and the formation of vascular bundles or channel structures during pyrolysis (Kim W. K. et al., 2013; Li et al., 2013). PLoS ONE 9:e113888. The peak around 1,026 cm1 is attributed to C-O stretching vibrations or the C-N stretch of an aliphatic primary amine (Coates, 2006). Sorption of heavy metals on chitosan-modified biochars and its biological effects. Biofuels production through biomass pyrolysisa technological review. doi: 10.1016/j.jenvman.2010.09.008, Imam, T., and Capareda, S. (2012). Int. doi: 10.1016/j.jtice.2016.02.012, Gai, X., Wang, H., Liu, J., Zhai, L., Liu, S., Ren, T., et al. This leads to the generation of porosity more in the agro-industrial residues (CS and SB) than herbaceous residues (MS and SG). Similar observations are found in the literature and in our previous studies (Stankovich et al., 2006; Chen et al., 2014; Chatterjee et al., 2018, 2019; Sajjadi et al., 2019a). Similar to CS, it generally showed increased %C and ash content, and reduced H/C-O/C ratios and %N content, for the temperature range of 500800C, although values at 700C were often the most extreme. doi: 10.1039/C7GC03457A, Mia, S., Dijkstra, F. A., and Singh, B. Influence of pyrolysis temperature and heating rate on the production of bio-oil and char from safflower seed by pyrolysis, using a well-swept fixed-bed reactor. It is worth noting that the micro surface area of all biochars increased by almost 200 m2/g (on average) with a pyrolysis temperature increase of 500 to 700C. Effect of pyrolysis pressure and heating rate on radiata pine char structure and apparent gasification reactivity. FTIR spectra of raw and activated samples (A) miscanthus, (B) switchgrass, (C) corn stover, and (D) sugarcane bagasse synthesized at different pyrolysis temperatures. This further indicates the decrease of aliphatic hydrocarbon and development of aromatic structure of biochar with increasing pyrolysis temperature (Major et al., 2018) as found from elemental analysis results that showed increased %C content at elevated temperature (Table 3 and Table S1). BS: idea of the work, interpretation of results, and writing the manuscript. Various other support from the University of Mississippi is also gratefully acknowledged. The sonicated samples also showed significant increases in surface area (323 to 520 m2/g for MS, from 309 to 486 m2/g for SG, from 215 to 399 m2/g for CS, and 192332 m2/g for SB) with increasing the pyrolysis temperature from 500 to 600C. 35, 777815. Similar behavior was observed in the two agro-industrial-based biochars (CS and SB). (2015). ACS Sust. All the raw samples demonstrated a slight increase (413%) in CO2 capture capacity at 700C compared with 600C, which can be substantiated as per the elemental analysis data (C and N contents) (Table 3). J. Agric. *Correspondence: Baharak Sajjadi, bsajjadi@olemiss.edu, Biochar Modification Technologies for Sustainable Water, Energy and Food Nexus, View all 47, 74197423. The mass loss occurred slowly around 6070C, which is associated with the loss of the initial moisture of the raw sample observed in Figure 7A (Santos et al., 2015). doi: 10.1021/jf501139f, Cetin, E., Gupta, R., and Moghtaderi, B. This is mostly attributed to the further degradation of lignin and the reaction of aromatic condensation (Chen et al., 2012), which increases the release of volatile matter and creates more pores. All raw biochars exhibited a gradual increase in adsorption capacity in the range of 6788% while increasing the temperature from 500 to 600C. (2017). Distinguishing primary and secondary reactions of cellulose pyrolysis. doi: 10.1021/ef3018783, Li, H., Dong, X., Da Silva, E. B., De Oliveira, L. M., Chen, Y., and Ma, L. Q. Additionally, surface area and pore volumes were also enhanced at elevated temperatures up to 700C. Physicochemical characterization of miscanthus and its application in heavy metals removal from wastewaters. Figure 4. The spectra exhibit two prominent peaks at 1,400 and 1,600 cm1 designated as D and G peaks. Am. This trend can be correlated to Tables 2, 3 that showed significant changes in surface areas and elemental compositions, respectively, when pyrolysis temperature was increased from 500 to 600C, irrespective of the biochar type. Res. The plots correspond to the volume of adsorbed gas with respect to the relative pressure, indicating adsorption ability of the chars.
Pyrolysis 110, 277284. This trend is also corroborated based on Raman analysis. Lee et al. The XRD diffraction patterns were taken in the 2 range of 1080 for raw and ultrasound amine activated of miscanthus biochars synthesized at 500, 600, 700, and 800C. Table 2. doi: 10.1016/j.jaap.2014.09.016, Zambon, I., Colosimo, F., Monarca, D., Cecchini, M., Gallucci, F., Proto, A., et al. A-CS 600, A-CS-700, A-CS 800 exhibited stronger C-N peak over R-CS 600, R-CS 700, and R-CS 800. doi: 10.1016/j.biombioe.2014.01.004, Nwajiaku, I. M., Olanrewaju, J. S., Sato, K., Tokunari, T., Kitano, S., and Masunaga, T. (2018). But a further increase in pyrolysis temperature (to 800C) resulted in a reduction in %C content and similarly follows a reverse trend for other elemental constituents. Energy Fuels 27, 942953. Fuel 84, 13281334. Raman spectroscopy combines a prominent surface selectivity and an exceptional sensitivity to the degree of structural order (Ashworth et al., 2014).
51, 83598367. Adsorption capacities of raw and sono-aminated biochars synthesized under different temperature conditions are presented in Figure 9. This trend is further verified from the following physicochemical characterizations data. In addition, the most notable change in the ID/IG intensity ratio of both herbaceous and agro-industrial chars was observed when the temperature was raised from 500 to 600C followed by a slight increment from 600 to 800C. The results of the present study also generally exhibited enhancement of ash content with pyrolysis temperature, mainly due to the increase in the concentration of minerals (such as Na, Mg, Ca, K, etc.) The plots correspond to the volume of adsorbed gas with respect to the relative pressure, indicating adsorption ability of the chars. 88, 523531. doi: 10.1016/j.rser.2014.01.056, Rafiq, M. K., Bachmann, R. T., Rafiq, M. T., Shang, Z., Joseph, S., and Long, R. (2016). doi: 10.1016/j.jaap.2004.12.008, Guittonneau, F., Abdelouas, A., Grambow, B., and Huclier, S. (2010). 7, 269276. Increasing pyrolysis temperature had a significant effect on the elemental constituents and H/C (the degree of aromaticity) (Al-Wabel et al., 2013) and O/C (the degree of polarity) ratios (Mimmo et al., 2014) of raw biochars. Clean. (2016). (2019). In order to prevent misinterpretation concerning organic content, elemental analysis of aminated samples is discussed by eliminating the impact of ash alteration. Green preparation of magnetic biochar for the effective accumulation of Pb(II): performance and mechanism. As found from Table 2, upon sonication the microporous surface area and pore volumes for all the biochars increased. Effect of feedstock and pyrolysis temperature on properties of biochar governing end use efficacy.
CO2 adsorption capacities of both raw and sono-chemically activated biochar samples synthesized at different pyrolysis temperatures. indicates a more hydrophobic structure (Peterson et al., 2013). Although the pyrolysis temperature showed a slight effect on adsorption capacity of the raw biochars, it demonstrated a significant interaction with the acoustic-based amination process and the subsequent adsorption capacity of activated biochars. Pyrolysis 124, 7988. RC: conducting the experiments, interpretation of results, and writing the manuscript. For instance, elemental analysis results (Table 3) expressed intense %N contents for aminated biochars at 600C. The maximum values were observed for MS, ranging from 0.78 to 0.96 for 500 to 800C, respectively, consistent with their surface area data (Table 2). Similarly, A-SG 600 and A-SG-700 showed improved amination than R-SG 600 and R-SG 700. It is considered to be one of the most informative methods for investigation of the structural perfection of carbonaceous material (such as biochar). Appl. (2016). PLoS ONE 11:e0156894. Comparison of biochar properties from biomass residues produced by slow pyrolysis at 500C. doi: 10.1016/j.biombioe.2017.06.024, Zhang, J., Liu, J., and Liu, R. (2015). For each experimental run, a biochar sample of 2 g was put inside the tube and heated under helium (99.99%) gas flow (500 cm3 min1) at 378 K for 1 h to remove moistures from the adsorbent. 26, 390397. 62, 37913799. 9, 246253. Most of the biochars showed intensified peak at 1,4001,600 cm1 attributed to aromatic C=C stretching except for MS. Variables governing the initial stages of the synergisms of ultrasonic treatment of biochar in water with dissolved CO2. It can be concluded that elevated pyrolysis temperature showed overall reduction in elemental %N contents of both raw and aminated chars (Table S1), though a sudden jump in N content of almost all samples was observed at 800C. doi: 10.1021/sc300098e, Plaza, M., Pevida, C., Arias, B., Fermoso, J., Arenillas, A., Rubiera, F., et al. Brewer, C. E. (2012). Pyrolysis temperature induced changes in characteristics and chemical composition of biochar produced from conocarpus wastes.
Based on Figure 9, adsorption capacities for activated chars can be categorized as: 0.861.23, 2.152.53, 2.222.89, and 1.341.74 mmol/g for the temperature ranges of 500, 600, 700, and 800C, respectively. Carbon 43, 5366. Total Environ. (2018). Appl. The lower the ID/IG ratio, the higher the degree of graphitization of the carbonaceous structure. Biomass Bioenergy 37, 97105. This furthermore proves that the lower temperature derived biochars were less thermally stable than the higher temperature derived ones, probably because they were not fully carbonized (Sun et al., 2014; Zhao et al., 2017). Ultrason. 118, 536544. The increase in carbon content at higher temperature reflects the increasing degree of carbonization (Zhou et al., 2013) and the decrease in H and O contents is likely due to dehydration reactions, the decomposition of the oxygenated bonds, and the release of low molecular weight byproducts containing H and O. As observed, raw MS shows maximum adsorption capacities in comparison to all other raw chars (MS>SG>CS>SB) under all temperature ranges, although the differences are small.
Additionally, the effectiveness of the developed activation technique has been assessed based on the comparison of the adsorption capacities of the sorbent materials from the present study with the literature data and presented in Table S3. doi: 10.1016/j.fuel.2018.08.112, Antonakou, E., Lappas, A., Nilsen, M. H., Bouzga, A., and Stcker, M. (2006). Bioresour. Energies 7, 548567. SG also exhibit similar behavior where %C content showed gradual increment and %N content showed gradual reducing trend with temperature but C-N peak from IR showed improved intensity for aminated samples at 600 and 700C than raw SG under same temperatures. A., and Redwine, C. W. (2014). Images obtained revealed two main morphological features for all biochar samples: fiber structures and pith. doi: 10.1016/j.still.2015.10.002, Liu, Y., He, Z., and Uchimiya, M. (2015). Fundamental and molecular composition characteristics of biochars produced from sugarcane and rice crop residues and by-products. Energy 37, 10581067. doi: 10.1007/s40093018-0213-y, Onay, O. Ind. Biochar Characterization and Engineering Ames, IA. Elemental compositions (dry basis) of raw and activated biochar samples synthesized at different pyrolysis temperatures. This facility was supported in part by grant 1726880, National Science Foundation. Table S1 (organic analysis) depicts gradual increment in %C contents of aminated MS samples with temperature, which is consistent to what was obtained for raw chars. Figure 5. A., and Ashwath, N. (2012). These morphological observations were further substantiated based on the surface area analysis data using BET technique as described in the subsequent section. These intermediate temperatures are clearly the pyrolysis temperatures of choice for maximizing adsorption capacity. Pyrolysis 74, 307314. A., and Jaroniec, M. (2020). The peak at 1,600 cm1 is ascribed to carboxylate (COO-) and 1 amine N-H bending, (Liu et al., 2015) and aromatic C=C stretch is ~1,400 cm1 (Zhao et al., 2017). 8:85. doi: 10.3389/fenrg.2020.00085. Renew. J. Environ. Characterization of bio-oil, syn-gas and bio-char from switchgrass pyrolysis at various temperatures. doi: 10.1016/j.jaap.2011.11.010, Inyang, M., Gao, B., Pullammanappallil, P., Ding, W., and Zimmerman, A. R. (2010). Application of thermogravimetric analysis to the evaluation of aminated solid sorbents for CO2 capture. Chem. The production of engineered biochars in a vertical auger pyrolysis reactor for carbon sequestration. min1) at a heating rate of 5C min1, from 21 to 700C.
Biomass-based pyrolytic polygeneration system on cotton stalk pyrolysis: influence of temperature. 20, 22692278. Effects of feedstock type and pyrolysis temperature on potential applications of biochar. The surface area of the samples can be further justified based on the adsorption isotherm plots as observed in the Figures S2, S3.
An innovative agro-forestry supply chain for residual biomass: physicochemical characterisation of biochar from olive and hazelnut pellets.
In addition to that, all samples exhibit fracture and cracks attributed to release of volatile matters during pyrolysis.