热解温度对山地城市污泥生物炭吸附Cu(Ⅱ)及其固碳作用的影响

Effects of pyrolysis temperature on carbon sequestration potential and Cu(Ⅱ)adsorption properties of biochar derived from municipal sludge in mountainous cities

由我国典型山地城市重庆的某污水厂污泥热解制备生物炭。使用X射线衍射、X射线荧光和傅里叶变换红外光谱等对产物进行了物性测定,评价了热解温度对生物炭吸附Cu(Ⅱ)、碳保留率(YC)、固定碳产率(YFC)和热稳定性的影响。结果表明,热解温度低于300℃时,生物炭对Cu(Ⅱ)的吸附能力差异较小;高于300℃时,随热解温度升高,生物炭对Cu(Ⅱ)的吸附能力降低。由于生物炭中的灰分以SiO2为主,并不影响生物炭对Cu(Ⅱ)的吸附,其吸附机理主要受含氧官能团和比表面积的制约。此外,YFC比单独使用YC或热稳定性更能综合衡量生物炭固碳作用。热解温度为300℃时,生物炭的YFC值最大,固碳效果最佳。因此,从对Cu(Ⅱ)的吸附能力和固碳效果两方面考虑,山地城市污泥制备生物炭的热解温度为300℃。

Biochar was prepared from the sludge of wastewater treatment plant in Chongqing at pyrolysis temperatures,and its physical properties was characterized by X-ray diffraction,X-ray fluorescence and Fourier transform infrared spectroscopy,the effect of pyrolysis temperature on the adsorption of Cu(Ⅱ)was evaluated by the adsorption of biochar;and the carbon sequestration potential of biochar was evaluated by carbon retention(YC),fixed carbon yield(YFC)and thermal stability.The results showed that the adsorption capacity difference of biochar for Cu(Ⅱ)was little when the pyrolysis temperature was lower than 300℃.However,with the increase of pyrolysis temperature above 300℃,the adsorption capacity of Cu(Ⅱ)on biochar decreased.The ash in biochar is mainly SiO2,it did not contribute to the adsorption of Cu(Ⅱ)on biochar,the adsorption capacity of biochar for Cu(Ⅱ)was restricted by oxygen-containing functional groups and specific surface area.In addition,YFCcould comprehensively measure the carbon sequestration effect of biochar than YCor thermal stability alone.The YFCof 300℃biochar was the largest and the carbon fixation effect was the best.Considering the adsorption capacity of Cu(Ⅱ)and carbon sequestration potential,it was suggested that the pyrolysis temperature of biochar prepared from municipal sludge in mountainous cities should be set at 300℃.