四种生物炭的理化性质及其对亚甲基蓝吸附性能研究

Study on Physicochemical Properties of Four Biochars and their Adsorption to Methylene Blue

采用限氧裂解法在500℃高温下制备水稻秆、玉米秆、香蕉皮和柚子皮四种生物炭,计算了生物炭的炭产率,利用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)和X射线衍射(XRD)对生物炭结构、形貌、表面官能团和结晶度等进行表征,并分析其与生物炭吸附性的关系。结果表明,香蕉皮的炭产率最高(39.5%),柚子皮的炭产率最低(32.8%);秸秆生物炭比果皮生物炭孔径大,这是因为秸秆中纤维素、半纤维素等含量更高,高温下大量分解;秸秆生物炭的晶体化程度更高,稳定性更好,处理污染物的效果更佳;在1 600 cm^(-1)附近秸秆生物炭比果皮生物炭的羧基、酯基或醛基等官能团强度更大,对亚甲基蓝的吸附起到一定的促进作用;四种生物炭对亚甲基蓝的吸附能力依次为:水稻秆生物炭>玉米秆生物炭>香蕉皮生物炭>柚子皮生物炭,说明秸秆生物炭去除染料废水中亚甲基蓝的效果更佳,其中水稻秆生物炭吸附性最好。

Four kinds of biochars from rice stalk, corn stalk, banana peel and pomelo peel were prepared by oxygen cracking method at a high temperature of 500 ℃. The carbon yields of biochars were calculated and the scanning electron microscope(SEM), fourier transform infrared spectroscopy(FTIR) and X-ray diffraction(XRD) were used to characterize the structures, morphologies, surface functional groups, and crystallinity of biochars, and their relationship with adsorption of biochars were analyzed. The results showed that the carbon yield of banana peel was the highest(39.5%), and that of pomelo peel is the lowest(32.8%). Bore aperture of straw biochar was larger than that of pericarp biochar, which was due to the higher content of cellulose and hemicellulose in straw which would decompose at high temperatures. Straw biochar had a higher degree of crystallization, better stability, and better treatment of pollutants. Near 1 600 cm^-1, functional groups such as carboxyl group, ester group or aldehyde group of straw biochar had greater strength than those of pericarp biochar, which would promote the adsorption of methylene blue. The adsorption abilities of the four type of biochar to methylene blue from high to low were rice stalk biochar, corn stalk biochar, banana peel biochar and pomelo peel biochar, indicating that straw biochar could remove methyl blue from dye wastewater more effectively.