Biochar physicochemical properties: pyrolysis temperature and feedstock kind effects

Abstract

Biochar is a pyrogenous, organic material synthesized through pyrolysis of different biomass (plant or animal waste). The potential biochar applications include: (1) pollution remediation due to high CEC and specific surface area; (2) soil fertility improvement on the way of liming effect, enrichment in volatile matter and increase of pore volume, (3) carbon sequestration due to carbon and ash content, etc. Biochar properties are affected by several technological parameters, mainly pyrolysis temperature and feedstock kind, which differentiation can lead to products with a wide range of values of pH, specific surface area, pore volume, CEC, volatile matter, ash and carbon content. High pyrolysis temperature promotes the production of biochar with a strongly developed specific surface area, high porosity, pH as well as content of ash and carbon, but with low values of CEC and content of volatile matter. This is most likely due to significant degree of organic matter decomposition. Biochars produced from animal litter and solid waste feedstocks exhibit lower surface areas, carbon content, volatile matter and high CEC compared to biochars produced from crop residue and wood biomass, even at higher pyrolysis temperatures. The reason for this difference is considerable variation in lignin and cellulose content as well as in moisture content of biomass. The physicochemical properties of biochar determine application of this biomaterial as an additive to improve soil quality. This review succinctly presents the impact of pyrolysis temperature and the type of biomass on the physicochemical characteristics of biochar and its impact on soil fertility.

Biochar and its importance on nutrient dynamics in soil and plant

“…Additionally, it was confirmed that there were hydrophilic functional groups on the surface and pores of biochar with a high affinity for water; biochar application was shown to increase soil water retention more in a sandy soil than a loamy soil or a clay soil (Mandal et al 2020). Biochar also showed a positive impact on surface area of soil (Anawar et al 2015), which varied with biochar types (Tomczyk et al 2020). For example, biochar (10%)-amended soil had 3 times higher surface area than untreatedd soil (Tomczyk et al 2019).…”

“…However, in a field study, application of a paddy straw-derived biochar (biochar pH was 10.50) to a sandy soil (soil pH 5.24) increased the pH of the soil by 4.5 units compared to the control (El-Naggar et al 2018b). Moreover, a high dose (50 and 100 t ha −1 ) of biochar (pH 9.40) increased the pH of an Alfisol and, consequently, reduced exchangeable Al concentration in the soil (Tomczyk et al 2020). observed that application of biochar (10, 20, 40, and 60 t ha −1 ) had no impact on soil pH in a semi-arid region, which was consistent with the results reported by Werner et al (2018) who found that the pH of a sandy loam soil was not changed with addition of biochar.…”

“…Biochars derived from manure-and biosolid-based feedstock materials generally contain higher levels of N and P than those derived from wood-and straw-based feedstock materials (El-Naggar et al 2019a;Purakayastha et al 2019). While the N content decreases with increasing pyrolytic temperature through gaseous emission (Leng et al 2020), the P and K contents increase due to an increase in ash content (Christel et al 2016;Tomczyk et al 2020;Wang et al 2013). As a nutrient sink, biochar can retain nutrients, thereby reducing their losses through leaching and gaseous emission.…”

Poly(lactic Acid)–Biochar Biocomposites: Effect of Processing and Filler Content on Rheological, Thermal, and Mechanical Properties

“…Recently, biochar (BC) has attracted increasing interest as far as its utilization as filler for polymer-based composites, either thermoplastics or thermosets, is concerned [19,20]. BC is usually obtained from the pyrolysis of agricultural and forestry wastes [21], and its structure can be tuned depending on the pyrolysis conditions; in particular, by adjusting the temperature and the oxygen flow, the degree of internal porosity and the presence of different functional groups anchored to the surface can be tailored [22]. The interest towards BC lies in its intriguing properties, such as high chemical and thermal stability, great electric properties, and very large surface area [23], combined with its cost effectiveness and low environmental impact [24].…”

Slow Catalytic Pyrolysis of <i>Saccharum munja</i> using Bio-genically Synthesized Nickel Ferrite Nanoparticles for the Production of high yield Biofuel

“…High residence time also affects the quality and amount of biofuel obtained (Tippayawong et al, 2008). In slow pyrolysis, the major by-product obtained is biochar (Tomczyk et al, 2020). The slow pyrolysis process takes more time (up to an hour) for completion as compared to flash and fast pyrolysis.…”