Abstract Elephant grass is a plant that grows easily and rapidly, with low nutrient requirements. One of the possible applications of this raw biomass is as a renewable source for simple and low-cost production of carbon materials. The objective of this work was to use elephant grass biomass to produce biochar intended for the treatment of contaminated water. Biochars were produced with variation of the pyrolysis parameters, using three different temperatures (350, 600, and 900 °C) and two different residence times (30 and 120 min). The products were characterized by DRIFT spectroscopy, XRD, Raman imaging, EPR, TGA, SEM, TEM, nitrogen adsorption at 77 K, potentiometric titration to obtain the pKa values, and elemental CHN analysis. Continuous flow adsorption tests were used to evaluate the potential of the material for practical applications. The infrared spectra and pKa values revealed structural changes of the carboxylic groups (pKa 3–6), forming lactones (pKa 6–9) or phenols (pKa >9). The diffractograms, low H/C and O/C ratios, and Raman spectra indicated the formation of aromatic and graphitic structures in the materials. Environmentally persistent free radicals, mainly formed by constituents of lignin, were centered near to carbon atoms in samples produced at higher temperatures. Continuous flow adsorption tests showed that the sample with the highest surface area (∼550 m² g−1) and the largest pore volume (∼0.34 cm³ g−1) achieved a removal efficiency of 96.5 % and presented good reusability, indicating its suitability as a promising material for the treatment of water contaminated with aromatic pollutants.

中文翻译：

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使用简单且低成本的方法生产高性能生物炭：热解参数优化和水处理评价

摘要 象草是一种生长速度快、营养需求低的植物。这种生物质的可能应用之一是作为一种可再生资源，用于简单、低成本地生产碳材料。这项工作的目的是使用象草生物质来生产用于处理受污染水的生物炭。使用三种不同的温度（350、600 和 900 °C）和两种不同的停留时间（30 和 120 分钟），生产生物炭的热解参数会发生变化。通过漂移光谱、XRD、拉曼成像、EPR、TGA、SEM、TEM、77 K 氮吸附、电位滴定获得 pKa 值和元素 CHN 分析对产物进行表征。连续流动吸附测试用于评估材料在实际应用中的潜力。红外光谱和 pKa 值揭示了羧基 (pKa 3-6) 的结构变化，形成内酯 (pKa 6-9) 或酚 (pKa > 9)。衍射图、低 H/C 和 O/C 比以及拉曼光谱表明材料中形成了芳香族和石墨结构。环境持久性自由基，主要由木质素成分形成，集中在较高温度下生产的样品中的碳原子附近。连续流吸附测试表明，具有最高表面积（~550 m² g-1）和最大孔体积（~0.34 cm³ g-1）的样品实现了 96.5 % 的去除效率并呈现出良好的可重复使用性，表明其适用于作为一种用于处理被芳香族污染物污染的水的有前途的材料。