A type of rayon-based commercial activated carbon fibers (ACFs), named as KF1500, was modified by thermal chemical vapor deposition (CVD) method to remove nitrate in aqueous solution. Acetonitrile (vapor) was introduced to dope positive charge nitrogen species on it. The sample was ded as KF-8ST10-8AN20-9.5HT30-8ST30 (8ST10; steam activation at 800 °C with 10 mL water, 8AN20; thermal CVD treatment at 800 °C charging 20 mL acetonitrile, 9.5HT30; annealing at 950 °C for 30 min, 8ST30; steam activation at 800 °C with 30 mL water), obtaining great nitrate adsorption capacity of 0.74 mmol/g in 200 mg/L nitrate solution at pH 3.0. For deeply exploring the adsorption characteristics of this well-modified ACFs, in this study, the pH of point of zero charge (pH_pzc) for KF8ST10-8AN20-9.5HT30-8ST30 as well as KF1500 has been explored to further understand the surface charge properties. The results indicated that pH_pzc was 7.2 for KF1500 and that for modified ACFs KF-8ST10-8AN20-9.5HT30-8ST30 was about pH_pzc 7.0. Effect of solution pH at various initial solution concentrations was also studied, and adsorption isotherms were well fitted by Langmuir model at pH 1.5–8, and adsorption capacity obtained from the fitting was 0.67 mmol/g (R² = 0.993). In addition, the effect of temperature (15–35 °C) on nitrate adsorption was also tested. Moreover, desorption of nitrate hydrochloric acid solution proceeded for 3 h at pH 3. With the above results, the working condition of quaternary nitrogen (N–Q) and carbon π bond was investigated, and the contribution to nitrate adsorption by N–Q was also defined more clearly which was 22% at least.

中文翻译：

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多因素分析研究氮掺杂活性炭纤维去除硝酸根离子的特性

通过热化学气相沉积（CVD）方法对一种基于人造丝的商品化活性炭纤维（ACF）进行了改性，以去除水溶液中的硝酸盐，将其命名为KF1500。引入乙腈（蒸气）以在其上掺杂正电荷氮。将该样品定为KF-8ST10-8AN20-9.5HT30-8ST30（8ST10;在800°C下用10 mL水活化8AN20进行蒸汽活化;在800°C下进行热CVD处理，加入20 mL乙腈9.5HT30;在950°C下退火在8ST30中保持30分钟；在800°C下用30 mL水活化），在200 mg / L硝酸盐溶液（pH 3.0）中获得0.74 mmol / g的高硝酸盐吸附能力。为了深入研究这种改性良好的ACF的吸附特性，本研究中采用零电荷点的pH值（pH _pzc）已针对KF8ST10-8AN20-9.5HT30-8ST30以及KF1500进行了研究，以进一步了解表面电荷特性。结果表明，pH值_PZC是7.2 KF1500并且对于改性的ACF KF-8ST10-8AN20-9.5HT30-8ST30是约pH _PZC 7.0。还研究了溶液pH值在各种初始溶液浓度下的影响，并通过Langmuir模型在pH 1.5-8下很好地拟合了吸附等温线，从拟合中获得的吸附容量为0.67 mmol / g（R ² = 0.993）。此外，还测试了温度（15–35°C）对硝酸盐吸附的影响。此外，硝酸盐溶液在pH 3下的解吸过程进行了3 h。根据以上结果，研究了季氮（N–Q）和碳π键的工作条件，得出N–Q对硝酸盐吸附的贡献为也更清楚地定义了至少22％。