Pyrolysis temperature induced changes in characteristics and chemical composition of biochar produced from conocarpus wastes

Pyrolysis conditions directly influence biochar properties and, consequently, influence the potential use of biochar. In this study, we evaluated the effects of different pyrolysis temperatures (450, 550, 650, 750, 850, and 950 °C) on the hydrogen potential, electrical conductivity, ash content, yield, volatile matter content, elemental analysis, Fourier-transform infrared spectroscopy results, X-ray diffraction results, scanning electron microscopy results, specific surface area, and micropore volume of eucalyptus wood-derived biochar. The degree of linear association between pyrolysis temperatures and biochar properties was examined using the Pearson correlation coefficient. The results showed a positive correlation of the pyrolysis temperature with the hydrogen potential value, electrical conductivity, and elemental carbon. There was a negative correlation of the pyrolysis temperature with the yield, volatile matter content, elemental oxygen, elemental hydrogen, surface area, aromaticity, hydrophilicity, and polarity indexes. The Fourier-transform infrared spectroscopy data indicated an increase in aromaticity and a decrease in the polarity of high-temperature biochar. The increased pyrolysis temperature caused the loss of cellulose and crystalline mineral components, as indicated by X-ray diffraction analysis and scanning electron microscopy images. These results indicated that changing the pyrolysis temperature enables the production of biochar from the same raw material with a wide range of physicochemical properties, which allows its use in various types of agricultural and environmental activities.

Effects of pyrolysis temperature and heating time on biochar obtained from the pyrolysis of straw and lignosulfonate

The present study examined the effect of pyrolysis temperature on the physicochemical properties of biochar produced from guinea corn straws at different temperatures (300-600℃). However, the produced biochars were designated as BCG-300, BCG-400, BCG-500 and BCG-600, respectively. The produced biochar’s were characterized by different analytical techniques. These include; the proximate and elemental analyses, morphological, crystallographic, functional groups and specific surface area analyses were investigated using elemental analyzer, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and Brunauer–Emmett–Teller (BET), respectively. The results indicated that. increasing pyrolysis temperature increased the content of fixed carbon (C), the C content, the total content of K, Ca, and Fe, as well as the cation exchange capacity (CEC), pH, and EC. While the yield, the content of volatile matter O and H, and the ratios of O/C and H/C decreased. Additionally, at higher pyrolysis temperature, the BET surface area and pore volume increased with increased in temperature, typically due to the increase of the micropore surface area and micropore volume. Furthermore, the data of Fourier transformation infrared showed that at higher pyrolysis temperature, the biochar aromaticity increased and decreased in polarity. Similarly, the crystalline mineral components increased with pyrolysis temperatures due to the cellulose loss, as indicated by X-ray diffraction analysis and scanning electron microscope images. Hence, pyrolysis temperature has a strong effect on biochar properties, and therefore biochars can be produced by changing pyrolysis temperature in order to meet their applications, such as carbon sequestration, greenhouse gas mitigation and as an adsorbent for organic and inorganic contaminants when applied to the environment etc.

Conversion of Organic Municipal Wastes into Biochars and their Effect on Fertility Parameters of Normal and Sabkha Soils of Qatar

The purposes of this research were to investigate the competence of coconut fiber to produce biochar by slow pyrolysis process and analyze the effects of different pyrolysis temperatures on the yield and physicochemical properties of biochars. Coconut fiber biomass was subjected to slow pyrolysis process using a laboratory scale fixed bed reactor at six different temperatures ranging from 350 to 600 °C (at an interval of 50 °C). The slow pyrolysis process was carried out in an inert environment for 1 (one) hour at a constant heating rate of 10 °C/min. The physicochemical properties of biomass and obtained biochars were characterized by proximate analysis (VM, FC, ash), ultimate analysis (CHNSO), higher heating value (HHV), bulk density, BET surface area, pH, and electrical conductivity (EC). Functional groups and particle sizes of biomass and biochars were identified by FTIR and particle size distribution respectively. Surface morphology and pore distribution of the biochars were observed by SEM images. The pyrolysis temperature had a negative effect on biochar yield and reduced from 48.13 to 29.34% as the pyrolysis temperature increased from 350 to 600 °C. Fixed carbon, ash content, pH, organic carbon, specific surface area, EC, degree of aromaticity, and porosity of the biochars enhanced as the pyrolysis temperature rose from 350 to 600 °C. However, the volatile matter, VM/FC ratio, H/C ratio, HHV, bulk density, and particle sizes of biochars were negatively correlated with the pyrolysis temperatures. Higher pyrolysis temperatures increased aromatic C groups and recalcitrant characteristics, yielded smaller particles, and formed elongated and porous structures. The physicochemical properties of high-temperature biochars (500–600 °C) showed the potential to be used as soil amendments and an efficient tool for C sequestration and retention of nutrients, and water. The porous structures of high-temperature biochars can accommodate suitable soil-microorganism activities, increase water sorption, and increase soil density. Moreover, the high alkalinity of the biochars can assist to neutralize acidic soil and increases soil fertility and plant growth. On the contrary, low-temperature biochars (350–450 °C) are promising tools for solid fuels.

In the present work, the olive mill solid waste (OMSW)-derived biochar (BC) was produced at various pyrolytic temperatures (300-700°C) and characterized to investigate its potential negative versus positive application effects on pH, electrical conductivity (EC), and nutrients (P, K, Na, Ca, Mg, Fe, Mn, Zn, and Cu) availability in a calcareous loamy sand soil. Therefore, a greenhouse pot experiment with maize (Zea mays L.) was conducted using treatments consisting of a control (CK), inorganic fertilizer of NPK (INF), and 1% and 3% (w/w) of OMSW-derived BCs. The results showed that BC yield, volatile matter, functional groups, and zeta potential decreased with pyrolytic temperature, whereas BC pH, EC, and its contents of ash and fixed carbon increased with pyrolytic temperature. The changes in the BC properties with increasing pyrolytic temperatures reflected on soil pH, EC and the performance of soil nutrients availability. The BC application, especially with increasing pyrolytic temperature and/or application rate, significantly increased soil pH, EC, NH4OAc-extractable K, Na, Ca, and Mg, and ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable Fe and Zn, while AB-DTPA-extractable Mn decreased. The application of 1% and 3% BC, respectively, increased the NH4OAc-extractable K by 2.5 and 5.2-fold for BC300, by 3.2 and 8.0-fold for BC500, and by 3.3 and 8.9-fold for BC700 compared with that of untreated soil. The results also showed significant increase in shoot content of K, Na, and Zn, while there was significant decrease in shoot content of P, Ca, Mg, and Mn. Furthermore, no significant effects were observed for maize growth as a result of BC addition. In conclusion, OMSW-derived BC can potentially have positive effects on the enhancement of soil K availability and its plant content but it reduced shoot nutrients, especially for P, Ca, Mg, and Mn; therefore, application of OMSW-derived BC to calcareous soil might be restricted.

In the present work, the olive mill solid waste (OMSW)-derived biochar (BC) was produced at various pyrolytic temperatures (300–700°C) and characterized to investigate its potential negative versus positive application effects on pH, electrical conductivity (EC), and nutrients (P, K, Na, Ca, Mg, Fe, Mn, Zn, and Cu) availability in a calcareous loamy sand soil. Therefore, a greenhouse pot experiment with maize (Zea mays L.) was conducted using treatments consisting of a control (CK), inorganic fertilizer of NPK (INF), and 1% and 3% (w/w) of OMSW-derived BCs. The results showed that BC yield, volatile matter, functional groups, and zeta potential decreased with pyrolytic temperature, whereas BC pH, EC, and its contents of ash and fixed carbon increased with pyrolytic temperature. The changes in the BC properties with increasing pyrolytic temperatures reflected on soil pH, EC and the performance of soil nutrients availability. The BC application, especially with increasing pyrolytic temperature and/or application rate, significantly increased soil pH, EC, NH4OAc-extractable K, Na, Ca, and Mg, and ammonium bicarbonate-diethylenetriaminepentaacetic acid (AB-DTPA)-extractable Fe and Zn, while AB-DTPA-extractable Mn decreased. The application of 1% and 3% BC, respectively, increased the NH4OAc-extractable K by 2.5 and 5.2-fold for BC300, by 3.2 and 8.0-fold for BC500, and by 3.3 and 8.9-fold for BC700 compared with that of untreated soil. The results also showed significant increase in shoot content of K, Na, and Zn, while there was significant decrease in shoot content of P, Ca, Mg, and Mn. Furthermore, no significant effects were observed for maize growth as a result of BC addition. In conclusion, OMSW-derived BC can potentially have positive effects on the enhancement of soil K availability and its plant content but it reduced shoot nutrients, especially for P, Ca, Mg, and Mn; therefore, application of OMSW-derived BC to calcareous soil might be restricted.

In this paper, rice straw was pyrolyzed at three temperatures (400, 500 and 600 °C) to study its influence on biochars properties and its chemical composition as soil amendment. Elemental analysis, surface area, pore size distributions, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) were used in the characterization of resultant biochar. As pyrolysis temperature increased, ash content, yield, acidity, total hydrogen and oxygen contents decreased while total carbon, nitrogen and basicity decreased by the reason of pyrolytic volatilization through pyrolysis. Surface area, total pore, micropore and mesopore volume reach its maximum at pyrolysis temperature of 500 °C in biochar-500. Biochars exhibit wide particle size distribution, from narrow micropores ( 2.0 nm). One sharp peaks was obtained at about 1.0–1.5 nm in the case of micropore region and two broad peaks at about 3.0 and 5.0 nm in mesopore region. FTIR spectra exhibited that high pyrolysis temperatures induce condensation reactions, which leads to aromaticity increasing and decreasing of biochar polarity. With increasing of pyrolysis temperature, cellulose loss and minerals contents increased, as showed by XRD analysis. Results recommend that high pyrolysis temperature give biochar with higher carbon sequestration potential characteristics when applied as soil amendment. Rice-based biochars gave high adsorption capacity for various molecular sizes like phenol, iodine and methylene blue. Biochars acidity/alkalinity and hydrophilicity represents one of the most important property that affecting their solution adsorption behavior.

Influence of pyrolysis atmosphere, temperature, and particle size co-regulation on the physicochemical properties of bone char

ABSTRACTHere we selected eight types of feedstocks to assess the effects of pyrolysis temperature (300°C, 400°C, 500°C and 600°C) and residence time (0.5, 1, 2, 4, 8 and 24 h), respectively, on the physicochemical properties. The fixed-carbon content, pH value and amount of basic functional groups in biochars increased as the pyrolysis temperature increased from 300°C to 600°C; the opposite trend was found in the biochar yield, adsorption capacity and amount of acidic functional groups. Increasing the residence time at low pyrolysis temperature (300°C) resulted in a gradual reduction in the biochar yield and progressive increase in the pH and iodine adsorption number of biochars. However, increasing the residence time at high pyrolysis temperature (600°C) had little effect on the biochar yield or pH, while it decreased the iodine adsorption number of biochars. Given the effects of pyrolysis conditions on the pH and iodine adsorption number of biochars, low-ash agricultural wastes (e.g. wheat straw) can be pyrolysed at 300°C, 2 h to produce biochar for improving alkaline soils; high-ash agricultural wastes (e.g. sweet potato vine) and forest litter (e.g. fresh leaves of apricot tree) are preferably pyrolysed at 300°C, 4 h to produce biochar for use in acidic soils.

The composition and pyrolysis characteristics of 60 types of biomass waste from the following six source categories were compared: agricultural residues, woody pruning waste from gardens and lawns, aquatic plant material from eutrophic water bodies, nutshells and fruit peels, livestock manure and residual sludge from municipal wastewater treatment. The yield and physicochemical characteristics of the biochar produced from these feedstocks at 350 °C, 500 °C and 650 °C were also examined. Results of correlation and canonical correspondence analysis between feedstock composition and biochar properties showed that feedstock type played an important role in controlling yield and properties of biochars. The yields of biochar dry ash‐free (daf.) basis were positively correlated with cellulose, lignin and lignin/cellulose content of feedstock; and ash content hampered the biochar production. Furthermore, the intensity of correlation between biochar yield and its feedstock composition was improved with pyrolysis temperature and degree of feedstock decomposition. The fixed carbon content in biochar was also negatively influenced by ash content of feedstock, and it increased with increasing pyrolysis temperature when the ash content was below 34.57% in feedstock and decreased when the ash content exceeded. The fixed carbon production in biochar per unit ash‐free mass (af.) was positively related to cellulose, lignin and lignin/cellulose content in feedstock, which were same with the yield of biochar (daf.). But on the contrary, the volatiles content in biochar (af.) had negative correlation with these organic constituents. For most feedstocks, the differences in the biochar characteristics among the biomass categories were greater than within any individual category. C/N, H/C and O/C atomic ratio and bulk density of biochar from different types of biomass were also compared. The results will provide guidance for the reutilization of biomass wastes and production of biochar with specified properties for soil amendment applications.

Rice is the main food for Indonesian. In production, it produces rice husk in huge amounts as waste. Rice husks have tough fibers, so their natural decomposing takes a long time. One strategy to take advantage of and add value to rice husk waste is to convert it into biochar. Biochar is a material that produced by a pyrolysis process of organic material, which is beneficial for the soil. The quality of biochar is influenced by pyrolysis temperature. This research aimed to analyze the biochar characteristics under various pyrolysis temperatures. The results showed that increasing the pyrolysis temperature will increase the element concentration of SiO2 (ash fraction). On the other hand, increasing the pyrolysis temperature decreases the biochar yield, calorific value, carbon and hydrogen content, and K2O, CaO, P2O5, MnO, and TiO2 concentration. The dominant elemental content of biochar (ash fraction) is SiO2 with a concentration of 85.35–89.47%. Biochar yield was 37.4–68.18%. The carbon, hydrogen, and nitrogen content ranged from 31.77–38.11; 1.67–3.61; and 0.63–0.73%, respectively. The calorific value of the biochar ranged from 14.48 to 11.61 MJ/Kg. The highest biochar yield, with the highest carbon, hydrogen, and calorific value content, was obtained using the lowest pyrolysis temperature of 250 °C. Fourier transform infrared (FTIR) analysis showed that the functional groups in the biochars were O-H, C=O, and C-OH. Following the X-Ray diffraction (XRD) analysis result, the amorphous biochar of rice husk decreases with increasing pyrolysis temperature and vice versa. The rice husk biochar has excellent potential to produce silicate crystals.

Effects of aging after pyrolysis were tested relative to the physicochemical characteristics of peanut straw biochar. Biochar was prepared at pyrolysis temperatures of 350 °C, 500 °C, and 650 °C; then, it was freeze-thawed and dry-wet aged. The physicochemical characteristics of the fresh and aged biochar were analyzed. The results showed that the pyrolysis temperature, ambient temperature, and humidity affected the physicochemical characteristics of the biochar. With the increase of pyrolysis temperature, the yield and surface acidic functional groups of the fresh biochar decreased, whereas the ash content, C content, pH, specific surface area, and mesoporous volume of the fresh biochar increased. The aging treatment increased the acidic functional groups content in the biochar and reduced the aromatic functional groups content, which decreased the pH value of the biochar. The aging treatment increased the specific surface area and pore volume of the biochar, and the effect of freeze-thaw aging was greater than that of dry-wet aging. The aging treatment also destroyed the complete shape of the fresh biochar, and reduced its stability. After the aging treatment, the C content of the biochar decreased, whereas the O content increased, due to oxidation of the biochar.

Co-pyrolysis of agricultural and industrial wastes changes the composition and stability of biochars and can improve their agricultural and environmental benefits

Effect of pyrolysis temperature and correlation analysis on the yield and physicochemical properties of crop residue biochar