Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas (ICA-CSIC), Calle Serrano 115bis, 28006, Madrid, Spain.
Univ Gustave Eiffel, GERS-LEE, F-44344 Bouguenais, France.
Chemosphere. 2022 Nov;307(Pt 4):136071. doi: 10.1016/j.chemosphere.2022.136071. Epub 2022 Aug 19.
Biochar aging may affect the interactions of biochar with water and thus its performance as soil amendment; yet the specific mechanisms underlying these effects are poorly understood. By means of FTIR, N adsorption, Hg intrusion porosimetry, thermogravimetric analysis, C solid state nuclear magnetic resonance (NMR) and H NMR relaxometry, we investigated changes in the chemistry and structure of biochar as well as its interaction with water after biochar aging, both physical (simulated by ball-milling) and biochemical (simulated by co-composting). Three different porosities of biochar were examined: <5 nm, 1 μm and 10 μm diameter sizes. Physical aging caused the disappearance of the porosity at 10 μm. With biochemical aging, biochar underwent an enrichment of oxygenated functional groups either as a result of surface functionalisation processes or by the deposition of fresh organic matter layers on the surface and pores of biochar. H NMR relaxometry revealed that the proportion of water strongly interacting with biochar increased with both physical and biochemical aging. Although biochemical aging significantly altered the composition of biochar surface and modulates its interaction with water, H NMR relaxometry proved that physical aging had a relatively stronger influence on water mobility and dynamics in biochar, lowering both T and T relaxation times in the initial contact times of biochar and water.
生物炭老化可能会影响生物炭与水的相互作用，从而影响其作为土壤改良剂的性能；然而，这些影响的具体机制还知之甚少。本研究采用傅里叶变换红外光谱（FTIR）、氮气吸附、汞压入孔隙率分析、热重分析、C 固体核磁共振（NMR）和 H NMR 弛豫测量等方法，研究了生物炭老化后，其化学结构和与水的相互作用的变化，包括物理老化（通过球磨模拟）和生物化学老化（通过共堆肥模拟）。研究考察了三种不同孔径的生物炭：<5nm、1μm 和 10μm。物理老化导致 10μm 孔径的消失。在生物化学老化过程中，生物炭表面的富氧官能团发生了富集，这可能是由于表面功能化过程，也可能是由于新鲜有机物质层在生物炭表面和孔中的沉积。H NMR 弛豫测量表明，与生物炭强烈相互作用的水的比例随着物理和生物化学老化而增加。尽管生物化学老化显著改变了生物炭表面的组成，并调节了其与水的相互作用，但 H NMR 弛豫测量证明，物理老化对生物炭中水分的迁移和动力学有更强的影响，降低了生物炭和水最初接触时的 T 和 T 弛豫时间。
