Effects of Pyrolysis Conditions on Physicochemical Properties of Oat Hull Derived Biochar

Abstract

The effects of the pyrolysis conditions in terms of temperature (400 to 600 °C), residence time (0.5 to 3.5 h), nitrogen flux (0 to 1 L/min), and temperature increase rate (1.5 to 3 °C/min) on the physicochemical properties of biochar were studied. The physicochemical properties evaluated in the biochar were specific surface area, pore volume, average pore size, total carbon content, pH, total acidity, elemental composition, and polycyclic aromatic hydrocarbons (PAHs) content. A higher specific surface area of 108.28 m 2 /g and a mean pore size diameter of about 2.24 nm were found when the pyrolysis was conducted at 600 °C. In general, the pH and total acidity increased with the increased pyrolysis temperature. The total PAH concentration in all of the combinations studied varied from 0.16 to 8.73 μg/kg, and only phenanthrene, pyrene, and chrysene were detected. The increased temperature seemed to decrease the PAH concentration in the biochar. Nevertheless, there was no correlation found between the PAH content and the combined evaluated parameters.

Biochar produced from Amazonian agro-industrial wastes: properties and adsorbent potential of Cd2+ and Cu2+

“…Higher pyrolysis temperatures produce greater amounts of pores and irregular surfaces due to the volatilization of the organic components, degradation of functional groups, and decrease in the atomic ratios (Dong et al 2017). Higher biochar porosity is beneficial for promoting soil quality, as there is higher water and nutrient retention, serving as a habitat for microorganism symbiosis (González et al 2017).…”

Thermal and Kinetic Studies on Biomass Degradation via Thermogravimetric Analysis: A Combination of Model-Fitting and Model-Free Approach

“…By varying the pyrolysis temperature between 400 and 500 °C, Santos et al ( 38 ) studied the effect of the different temperatures on the properties of the pyrolytic products of oat hulls. González et al ( 39 ) studied the effects of heating rate, temperature, residence time, and nitrogen flux on the physicochemical properties of oat hull-derived biochar.…”

Polycyclic Aromatic Hydrocarbons Occurrences in Biomass Char and Its Mitigation Approaches: A Mini Review

“…The rising pyrolysis temperature at 700 °C was found to decrease the total PAHs concentration in the grass, wood, and paper mill effluent biochar to 0.19, 0.37, and 0.16 mg kg, respectively. Similarly, the maximum extractable yields of 3-4 ring PAHs compound from oat-hull derived biochar were obtained by Gonza ´lez et al [18] at 400 °C (8.73 mg kg -1 ). The lower total PAHs concentration was recorded at 600 °C (0.16 mg kg -1 ) with only phenanthrene and chrysene compounds identified in the biochar sample.…”

“…Many recent studies reported the dependence of PAHs formation in biochar influenced by pyrolysis conditions, biomass selection, and reactor configuration [5,10,[16][17][18][19]. Generally, different viewpoints and no overall trend were observed among the researchers.…”