Abstract:

In order to explore the response of physicochemical properties and adsorption properties of biochar to pyrolysis temperature and time， and clarify the appropriate time for preparing biochar at different pyrolysis temperatures， the garden waste branches were used as raw materials， and 5 pyrolysis times （12， 24， 36， 48， 60 min） were set at conventional pyrolysis temperatures of 450 and 650 ℃. The effects of pyrolysis time on biochar yield， pH， ash content， aromaticity， hydrophilicity， polarity and iodine adsorption value at different pyrolysis temperatures were analyzed. The results showed that the yield of biochar decreased with the increase of pyrolysis time. At 450 ℃， compared with 12 min pyrolysis treatment， the yield of biochar decreased significantly under 24， 36， 48 and 60 min pyrolysis treatments， but there was no significant difference among these treatments， and the above changes were consistent with those at 650 ℃. With the increase of pyrolysis time， the pH， ash content and aromaticity of biochar increased continuously， while the hydrophilicity and polarity decreased continuously. At 450 ℃， there was little or no significant difference in each index under 48 and 60 min pyrolysis treatments. At 650 ℃， there was no significant difference in pH of biochar under 24， 36， 48 and 60 min pyrolysis treatments， and there was no significant change in ash content， aromaticity， hydrophilicity and polarity of biochar under 36， 48 and 60 min pyrolysis treatments. With the increase of pyrolysis time， the iodine adsorption value of biochar increased continuously. At 450 ℃， the iodine adsorption value of biochar was the largest under 48 and 60 min pyrolysis treatments， which was higher than other treatments. At 650 ℃ for 36， 48 and 60 min pyrolysis， the pyrolysis time had no significant effect on the iodine adsorption value of biochar. Based on the changes of physical and chemical properties and adsorption properties of biochar， the pyrolysis time required for the preparation of biochar at 450 ℃ should not be less than 48 min， and the pyrolysis time at 650 ℃ should not be less than 36 min. Above the time value， the effect of pyrolysis time on the properties and functions of biochar should be significantly reduced.

Key words: biochar, pyrolysis temperature, pyrolysis time, physicochemical properties, adsorption properties

摘要：

为探究生物炭理化性质及吸附性能对热解温度及时间的响应规律，明确不同热解温度下制备生物炭的适宜时间，以园林废弃树枝为原料，在常规热解温度450、650 ℃下，分别设置12、24、36、48、60 min 共5个热解时间，分析不同热解温度下热解时间对生物炭产率、pH、灰分、芳香性、亲水性、极性、碘吸附值的影响规律及异同性。结果表明，随热解时间的增加，生物炭产率不断降低，在450 ℃下，与热解12 min处理相比，热解24、36、48、60 min处理下的生物炭产率显著降低，但这些处理间差异不显著； 650 ℃下也呈现出一致的变化规律。随着热解时间的增加，生物炭的pH、灰分含量、芳香性不断升高，亲水性和极性则表现为不断降低，在450 ℃下，各指标在热解48、60 min处理下差异较小或无显著差异；在650 ℃下，热解24、36、48、60 min处理间生物炭的pH无显著差异，热解36、48、60 min处理间生物炭的灰分含量、芳香性、亲水性和极性无明显变化。随着热解时间的增加，生物炭对碘的吸附值不断增加，在450 ℃下，热解48、60 min处理下生物炭的碘吸附值最大，显著高于其他处理；在650 ℃下，热解36、48、60 min处理下，热解时间对生物炭碘吸附值无显著影响。基于生物炭理化性质及吸附性能变化规律，在450 ℃下制备生物炭所需的热解时间不宜低于48 min，在650 ℃下的热解时间不宜低于36 min，超过以上时间，热解时间对生物炭性质及功能的影响显著降低。

关键词: 生物炭, 热解温度, 热解时间, 理化性质, 吸附性能