不同生物质原料水热生物炭特性的研究

以木屑、小麦秸秆和玉米秸秆为原料,采用水热法制备生物炭,研究不同生物质水热生物炭特性,分析了水热生物炭的产率、元素组成、表面特性、多环芳烃含量及表面官能团的变化。结果表明:以木屑为原料制备的水热生物炭产率最高(54.66%),C含量(52.59%)较水热小麦和玉米秸秆生物炭(分别为43.73%和43.93%)高,但O含量(41.56%)明显低于水热小麦和玉米秸秆生物炭(分别为49.94%和50.95%)。扫描电镜显示水热木屑生物炭表面光滑,孔状结构较多且排列整齐,水热小麦生物炭表面粗糙孔隙较少,而水热玉米生物炭孔隙结构不明显。傅里叶红外光谱分析显示原料经水热炭化后官能团种类差异不大,但相对含量发生了变化:水热小麦和玉米秸秆生物炭有机官能团含量相对增加,而无机矿物(如SiO2)含量略有减少;水热木屑生物炭有机官能团和无机矿物的含量均明显增加。采用气质联用仪(GC-MS)分析水热生物炭多环芳烃含量,结果表明三种水热生物炭总多环芳烃含量依次为水热小麦秸秆生物炭水热木屑生物炭水热玉米秸秆生物炭,并以菲和萘为主。

Properties of Hydrochars from Different Sources of Biomass Feedstock

Hydrothermal carbonization is a thermochemical process converting biomass into a coal-like material called hydrochar under biomass/water suspension conditions. Three hydrochars were prepared by hydrothermal carbonization(HTC) from three different feedstock sources of sawdust(SD), wheat straw(WS) and corn stalk(CS). Their characteristics including outputs, elemental contents, surface properties, PAHs concentrations and surface functional groups were investigated. Results showed that hydrochar from SD(H-SD) had the highest outputs(54.66%), and C content(52.59%), while O content was the lowest(41.56%). The SEM results showed that H-SD had smooth surface and neatly-arranged porous structure, whereas WS hydrochar(H-WS) was platy particles with rough surface while CS hydrochar(H-CS) did not have obvious pore structure. Hydrothermal carbonization did not change the types of functional groups but increased the contents of organic functional groups while decreased mineral components(such as SiO₂) in H-WS. However, both organic functional groups and mineral components significantly increased in H-SD. The PAHs concentrations of hydrochars were in order:H-WS > H-SD > H-CS, with phenanthrene and naphthalene being major components.