Thermal stability of biochar and its effects on cadmium sorption capacity

Abstract

In this study, the thermal stability of a wood shaving biochar (WS, 650°C), a chicken litter biochar (CL, 550°C) and an activated carbon (AC, 1100°C) were evaluated by combustion at 375°C for 24h to remove the labile non-carbonized organic matter. Results showed that WS and CL biochars were not thermally stable and can lose most of the organic C during combustion. The combusted WS and CL biochars retained considerable amounts of negative charge and displayed higher sorption for Cd (from 5.46 to 68.9mg/g for WS and from 48.5 to 60.9mg/g for CL). The AC retained 76.5% of its original C and became more negatively chargely after combustion, but its sorption for Cd slightly decreased (from 18.5 to 14.9mg/g). This study indicated that after potential burning in wildfires (200-500°C), biochars could have higher sorption capacity for metals by remaining minerals.

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

“…The adsorption capacities of the studied biochars, especially at 700 °C, were higher than biochars made from wood shaving (5.46 mg g −1 ) (Qi et al 2017), hickory (0.98 mg g −1 ) (Ding et al 2016), or even nut shield magnetic biochar (4.61 mg g −1 ) (Trakal et al 2016).…”

“…These lignocellulosic by-products can be reused for the production of biochar. Recently, biochar has attracted interest because of its capacity to adsorb metals, thereby acting as a green environmental sorbent in the remediation of soil and water (Huang et al 2019;Komnitsas et al 2015;Lehmann 2007;Li et al 2017a, b;Qi et al 2017;Uchimiya et al 2011;Wu et al 2019;Zhang et al 2015). The use of biochar in the remediation of contaminated areas has gained attention because of the usefulness of its properties, such as porosity, high cation exchange capacity, and alkalinity, which can aid in the immobilization of contaminants, reducing their toxicity (Huang et al 2019;Yuan et al 2011).…”

“…Several studies have demonstrated the ability of biochar to retain heavy metals, including Cd 2+ and Cu 2+ . For example, wood biochar and poultry litter biochar presented potential to reduce the availability of Cd 2+ in solution (Qi et al 2017). Biochar from earthworm humus exhibited a decrease in Cu 2+ adsorption with increasing temperature (Zhou et al 2017), and biochar from earthworm humus activated with HCl also exhibited high adsorption capacities of Cu 2+ and Cd 2+ .…”

Alleviation of aluminum and cadmium toxicity by biochar and its potential toxicity to sorghum

“…Feedstock like sugarcane bagasse present long-chain carbon compounds (such as lignin and cellulose) and usually produce biochars with higher yield and total carbon content (Lee et al, 2013). In addition, biochars generally present organic carbonaceous phases, like H, C, N, O, and S, rich in surface functional groups that contribute to the high pH, cation exchange capacity, and surface complexation for trace elements (Mukherjee, Zimmerman, & Harris, 2011). able 1).…”

“…At pyrolysis temperatures below 800 °C, the organic phase of biochars generally comprises carbonized organic matter (more aromatic and stable carbon) and non-carbonized organic matter (relatively aliphatic and less stable carbon), which may influence their adsorption capacity of metals (Qi et al, 2017b). In this study, biochars were produced at moderate pyrolysis temperatures (450 °C for BS and 350 °C for BB).…”