Incorporating pristine biochar into metal-organic frameworks: Facile green synthesis, characterization, and wastewater remediation

Biochar for Soil Carbon Sequestration: Current Knowledge, Mechanisms, and Future Perspectives

“…To quantify the thermal oxidative stability of biochar, the recalcitrance index (R 50 ) has been introduced based on temperature-programmed oxidation [84]. The R 50 index serves as a comparative indicator of stability in relation to graphite, offering insights into the thermal behavior of biochar.…”

“…The R 50 index serves as a comparative indicator of stability in relation to graphite, offering insights into the thermal behavior of biochar. It quantifies the temperature at which 50% of the biochar undergoes oxidation or volatilization (T 50,x ) and relates it to the standardization factor T 50 , graphite (T 50 = 885 • C) [84]. This calculation, depicted in Equation ( 3), provides a relative measure of biochar's thermal stability.…”

“…The values of T 50,x and T 50 are determined directly from TG thermograms after adjusting for water and ash content using the approach previously described [84]. The R 50 index for graphite is assigned the highest value (R 50 = 1), while biochars produced under different conditions exhibit R 50 values ranging from 0.37 to 0.61, with values positively correlated with high-temperature treatment (HTT) [84]. Researchers have utilized the R 50 index to characterize biochar, observing R 50 value ranges of 0.45-0.60 [85], 0.33-0.61 [86], and 0.41-0.83 [87].…”

“…Researchers have utilized the R 50 index to characterize biochar, observing R 50 value ranges of 0.45-0.60 [85], 0.33-0.61 [86], and 0.41-0.83 [87]. Remarkably, there is a pronounced inverse exponential correlation between the degradability of biochar (including both abiotic and biotic degradation) over a 1-year incubation period and its resistance to thermal oxidation during thermal degradation [84]. Built upon this relationship, a classification of biochar based on R 50 values has been proposed: Class A represents the highest stability with R 50 ≥ 0.70, Class B indicates lower stability but is still significantly higher than Class C (R 50 < 0.50), which resembles untreated biomass [84].…”