不同制备温度的水稻生物炭电子交换能力研究

为探究不同热解温度下生物炭的电子交换能力，通过限氧升温炭化法，利用水稻秸秆在不同热解温度条件下制备生物炭，与氧气、铁氰化钾氧化剂和柠檬酸钛还原剂进行氧化还原反应，对生物炭的得电子能力（EAC）和失电子能力（EDC）进行定量分析.结果显示，热解温度对生物炭的电子交换能力有较大影响，随热解温度升高至500℃时，生物炭的EAC和EDC达到最大，分别为3.86，1.72mmol/g高于500℃后，随着温度的增加，EAC和EDC逐渐减小，这是由于生物炭的醌类和酚类官能团的结构改变以及持久性自由基强度变化的联合作用.此外，柠檬酸钛和连二硫酸钠两种氧化还原电位不同的还原剂进一步证实了还原剂电位对生物炭EAC的影响.且生物炭具有氧化还原的可逆性，可逆的EAC与EDC之和近似等于生物炭的电子储存能力.

Electron exchange capacity of rice biochar at different preparation temperatures

In order to explore their electron exchange capacity, the biochars were prepared from rice straw at different pyrolysis temperatures by limited oxygen heating carbonization, then respectively oxidized with oxygen and potassium ferricyanide oxidants, and reduced with titanium citrate. The electron accepting capacities (EAC) and electron donating capacities (EDC) were quantitatively analyzed. The results show that different pyrolysis temperatures could affect the electronic storage capacity. At 500℃, both EAC and EDC of biochars has been maximized, which were 3.86 and 1.72 mmol/g, respectively. When the pyrolysis temperature increased above 500℃, EAC and EDC both decreased accordingly. This phenomenon is due to the combined action of quinones and phenols functional groups and persistent free radicals in biochar. In addition, titanium citrate and sodium dithionite had different redox potential as reductants, which further confirmed the effect of reductant potential on EAC. The biochars had reversible redox property, the sum of EAC and EDC was approximately equal to the electronic storage capacity of biochar.