Alkaline pretreatment of walnut shells increases pore surface hydrophilicity of derived biochars
Alkaline pretreatment of walnut shells increases pore surface hydrophilicity of derived biochars
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DOI：
10.1016/j.apsusc.2021.151253
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发表时间：
2021-09-20
影响因子：
6.7
通讯作者：
Volpe, Roberto
中科院分区：
文献类型：
--
作者：
Barr, Meredith Rose;Forster, Luke;Volpe, Roberto
核桃壳热解产生的生物炭的表面化学和形态影响其吸附应用的效用。然而，人们对这些材料的孔隙中的表面相互作用知之甚少，主要是由于以非破坏性的方式访问这种长度尺度的信息具有挑战性。在这里，第一次，溶剂的相对吸附强度，包括不同的官能团的内部（孔）表面的核桃壳和衍生生物炭进行了研究，使用低场核磁共振（NMR）弛豫时间测量，非破坏性地探测流体与孔表面的相互作用。这些材料的碳键合状态组合物相对于从颗粒表面的距离，使用X射线光电子能谱结合离子束蚀刻确定。碱预处理可以提高核桃壳和衍生生物炭的亲水性。它被发现增加表面与羟基的相互作用，并减少那些与甲基。通过热重分析、扫描电子显微镜和先前的原位X射线成像结果对结果进行了背景化。两者合计，结果表明，碱预处理可用于调节热解温度的几个因素，影响吸附性能，包括表面亲水性，颗粒大小，孔隙率，孔隙可达性，和表面纹理的响应。
The surface chemistry and morphology of biochars produced by pyrolysis of walnut shells affects their utility for adsorption applications. Yet, little is known about surface interactions in the pores of these materials, mostly due to the challenging nature of accessing information at this length scale in a non-destructive manner. Here, for the first time, the relative adsorption strengths of solvents comprising different functional groups to internal (pore) surfaces of walnut shells and derived biochars were investigated using low-field nuclear magnetic resonance (NMR) relaxation time measurements to non-destructively probe interactions of fluids with pore surfaces. Carbon bonding state compositions of these materials with respect to distance from the particle surface were determined using X-ray photoelectron spectroscopy coupled with ion beam etching. Alkaline pretreatment was found to increase the hydrophilicity of both walnut shells and derived biochars. It was found to increase surface interactions with hydroxyl groups, and to decrease those with methyl groups. Results were contextualised by thermogravimetric analysis, scanning electron microscopy, and previous in-situ X-ray imaging results. Taken together, results showed that alkaline pretreatment may be used to modulate responses to pyrolysis temperature of several factors that affect adsorption properties including surface hydrophilicity, particle size, porosity, pore accessibility, and surface texture.