Interaction of Inherent Minerals with Carbon during Biomass Pyrolysis Weakens Biochar Carbon Sequestration Potential

Abstract

Biomass carbon could be sequestrated in form of biochar, an aromatized carbon structure produced by pyrolysis. Inherent minerals are reactive constituents that interact with organic contents during pyrolysis, significantly affecting the properties of the pyrolysis product. Despite their importance, their influence on biochar-carbon sequestration has been rarely studied. This study selected four types of biomass: barley grass, peanut hull, cow manure and sewage sludge to investigate the influence of inherent minerals on carbon conversion during pyrolysis. Results showed removal of inherent minerals shifts the peak biomass conversion to a higher temperature (370 o C) compared to biomass with inherent minerals being present (330 o C). It also led to reduced emissions of low molecular weight organic compounds. Compared to pristine biomass, more carbon (3.5-30.1%) could be retained in biochar along pyrolysis after removing inherent minerals. And it showed increased resistance to chemical and thermal oxidation decomposition, indicating higher carbon stability and therefore carbon sequestration potential. Instrumental analysis showed removal of inherent minerals facilitated disappearance of oxygen-containing functional groups such as C=O, O=C-O and CO , while promoting C-C/C=C bonds, indicating higher aromatization of biochars. This study suggested that to remove minerals prior to pyrolysis can be a promising approach for strengthening carbon-sequestration potential of biochar.

Novel Recovered Compound Phosphate Fertilizer Produced from Sewage Sludge and Its Incinerated Ash

“…To efficiently recover P from P extract, pretreatment of SS is necessary to produce SSB with a high P sorption capability because raw SSB tends to adsorb cations rather than anions. , Accordingly, environmentally benign metals such as Mg, Al, Ca, Cu, and Fe have been impregnated into SS and produced modified SSB with more functional groups. ,, Impregnation with Ca/Mg produces SSBs with excellent P adsorption behaviors because of their various organic functional groups and the Ca/Mg-containing nanoparticles. − These Ca/Mg-containing nanoparticles play significant roles in P adsorption via electrostatic attractions with the formation of Ca–P/Mg–P bonds. ,− Additionally, Ca/Mg-based chemicals can induce the inherent P in SS to form plant-bioavailable phosphates, such as hydroxyapatite …”

“…5,25 Accordingly, environmentally benign metals such as Mg, Al, Ca, Cu, and Fe have been impregnated into SS and produced modified SSB with more functional groups. 24,26,27 Impregnation with Ca/Mg produces SSBs with excellent P adsorption behaviors because of their various organic functional groups and the Ca/Mg-containing nanoparticles. 28−30 These Ca/Mgcontaining nanoparticles play significant roles in P adsorption via electrostatic attractions with the formation of Ca−P/Mg−P bonds.…”

Sustainable Use of Biochar in Environmental Management

“…Biochar with high porosity and plenty of liming and fertiliser-related elements (such as N, P and K) is preferred for improving soil properties [31]. A study conducted by [32] also indicated that the innate minerals of biomass could affect biochar properties significantly through interaction with its organic contents during pyrolysis process. However, removal of these intrinsic minerals before the pyrolysis process could significantly increase the optimum pyrolysis temperature (370 vs. 350 °C) required for the conversion of the biomass into biochar, as compared to untouched biomass.…”

“…However, removal of these intrinsic minerals before the pyrolysis process could significantly increase the optimum pyrolysis temperature (370 vs. 350 °C) required for the conversion of the biomass into biochar, as compared to untouched biomass. Interestingly, about 30.1% of C content of biomass could be secluded into biochar when there are no inherent biomass materials, simultaneously, lower amounts of low-molecular-weight organic compounds would be emitted during pyrolysis [32]. Therefore, the type and amount of minerals in biomass must be optimised according to the intended environmental application of biochar.…”

Advances in the Characterization Methods of Biomass Pyrolysis Products

“…Nan et al. recently investigated the interaction of minerals in cow manure with biomass carbon along pyrolysis via TG-FTIR-MS . The gaseous products released from cow manure pyrolysis mainly included small molecules (such as acetic acid, butane, and so on), middle molecular compounds (such as furfural, furan, and pyrazole), and large molecular compounds (such as d -glucopyranoside, cortisol, cholestane, and so on).…”