Cold plasma generated from a gas admixture of helium and dry air with 60-Hz ac voltage at 6.50-kV rms was utilized to process biochar. Reactive oxygen and nitrogen species (RONS) were generated in the cold plasma and these chemical radicals modified the biochar. Plasma-processed biochar samples were immersed in distilled water after which the pH of the solid/water mixture was measured. This pH test provided a quick and reliable indication that the plasma-processing modified the biochar, after which more thorough tests were applied. The pH data showed that plasma-processed biochar/water admixtures have lower pH, indicating plasma processing introduced more acidic groups onto the biochar. After pH analysis the solid biochar granules were reclaimed from solution and the leachate was evaluated for carbon content resulting from material leaching into the distilled water. Fourier-transform infrared spectroscopy (FTIR) spectra were measured for dry samples of biochar before and after immersion in the distilled water. Cold plasma processing converted recalcitrant biochar mass into labile biochar mass, resulting in an enhanced amount of water-extractable carbon. FTIR spectra showed that new oxygen- and nitrogen-containing functional groups were introduced into the labile portion of the biochar and that functionalized material leached into solution.

中文翻译：

---

在常压干燥空气和氦气中使用电晕放电冷等离子体处理生物炭

由氦气和干燥空气的混合气体产生的冷等离子体，交流电压为 6.50 kV rms，交流电压为 60 赫兹，用于处理生物炭。在冷等离子体中产生活性氧和氮物质 (RONS)，这些化学自由基修饰了生物炭。将等离子体处理过的生物炭样品浸入蒸馏水中，然后测量固体/水混合物的 pH 值。该 pH 测试提供了一个快速可靠的迹象，表明等离子体处理改变了生物炭，之后进行了更彻底的测试。pH 值数据显示等离子体处理的生物炭/水混合物具有较低的 pH 值，表明等离子体处理在生物炭上引入了更多的酸性基团。在 pH 值分析后，固体生物炭颗粒从溶液中回收，并评估渗滤液的碳含量，这些碳含量是由浸出到蒸馏水中的材料引起的。在浸入蒸馏水中之前和之后，测量了生物炭干样品的傅里叶变换红外光谱 (FTIR) 光谱。冷等离子体处理将顽固的生物炭质量转化为不稳定的生物炭质量，从而增加了水可萃取碳的数量。FTIR 光谱表明，新的含氧和含氮官能团被引入生物炭的不稳定部分，并且官能化材料浸出到溶液中。冷等离子体处理将顽固的生物炭质量转化为不稳定的生物炭质量，从而增加了水可萃取碳的数量。FTIR 光谱表明，新的含氧和含氮官能团被引入生物炭的不稳定部分，并且官能化材料浸出到溶液中。冷等离子体处理将顽固的生物炭质量转化为不稳定的生物炭质量，从而增加了水可萃取碳的数量。FTIR 光谱表明，新的含氧和含氮官能团被引入生物炭的不稳定部分，并且官能化材料浸出到溶液中。