| 控氧热解过程中污染稻草生物炭的组分特性及其重金属累积特征 |
| 摘要点击 2186 全文点击 894 投稿时间：2022-03-16 修订日期：2022-05-18 |
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| 中文关键词 重金属污染稻草 生物炭 控氧热解 可溶性有机质(DOM) 芳香化指数 |
| 英文关键词 contaminated rice straw biochar oxygen-controlled pyrolysis dissolved organic matter (DOM) aromatization index |
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| 中文摘要 |
| 热解是实现重金属污染生物质无害化资源化的重要手段之一.以重金属污染稻草为原料，研究了控氧热解生物炭的组分特性及其重金属的累积特征.结果表明，低氧热解可有效利用污染稻草制备生物炭，提高重金属在生物炭中的稳定性.氮气氛条件下，稻草生物炭产率为29.4%~34.9%；可溶性有机质（DOM）以类腐殖酸物质为主，其芳香化指数（SUVA254）随热解温度升高呈先升后降趋势；生物炭中Ca主要以CaCO3形式存在.与氮气氛相比，10%和20%（体积分数，下同）氧气氛条件下生物炭（热解残渣）的产率分别降低5.6%~13.5%和14.9%~15.7%，但pH值提高0.5个单位以上；有氧气氛加速了热解过程中木质素组分的降解，生物炭中DOM的SUVA254值随热解温度升高逐渐降低.随热解气氛中氧体积分数提高，DOM中类腐殖酸物质向类富里酸物质转化；生物炭中Ca以CaO形式存在，这可能是导致生物炭pH值升高的原因之一.与氮气氛相比，10%氧气氛和400℃条件下，生物炭中Cu、Cd、Pb、Ni和As的可交换形态占比降低了5.2%、3.7%、1.7%、0.8%和0.7%，重金属在生物炭中的稳定性提高.结果表明，在10%氧气氛和400℃条件下能较好地将重金属稳定于生物炭中.自然条件下热解污染稻草过程中适当引入氮气（控制氧体积分数在10%）即可获得较高的生物炭产率及重金属稳定性，为有效实现污染稻草无害化资源化提供了一种经济可行的技术原型. |
| 英文摘要 |
| Pyrolysis is an important technology to achieve the harmlessness and recycling of contaminated biomass. In this study, the effects of oxygen-controlled atmosphere on the component properties and heavy metal accumulation characteristics of contaminated rice straw biochar were studied. The results showed that low-oxygen pyrolysis could effectively produce biochar using contaminated rice straw and improve the stability of heavy metals in biochar. Under the nitrogen atmosphere, the yield of rice straw biochar was 29.4%-34.9%. The aromatization index (SUVA254) of dissolved organic matter (DOM) increased first and then decreased with the increase in pyrolysis temperature, whereas the fluorescent components were mainly humic-like acid substances. Meanwhile, Ca mainly existed in the form of CaCO3 in biochar. Compared with the pure nitrogen condition, the biochar yield was reduced by 5.6%-13.5% and 14.9%-15.7% under the pyrolysis atmosphere containing 10% and 20% oxygen content, respectively. Ca existed in the form of CaO in biochar, which increased the pH value of the biochar by more than 0.5 units. The oxygen of the pyrolysis atmosphere accelerated the degradation of the lignin component, resulting in the gradual decrease in SUVA254 of DOM. With the increase in oxygen content in the pyrolysis atmosphere, humic-like acid substances in DOM were transformed into fulvic-like acid substances. Under the conditions of 400℃ and a 10% oxygen-containing atmosphere, the exchangeable fractions of Cu, Cd, Pb, Ni, and As in biochar were decreased by 5.2%, 3.7%, 1.7%, 0.8%, and 0.7%, respectively, indicating that heavy metals are transformed into more stable states. The results suggested that the higher biochar yield and heavy metal stability could be obtained by introducing a proper amount of nitrogen into the air (controlling the oxygen content of approximately 10%) for pyrolysis treatment of contaminated rice straw, providing an economic and feasible technology for the achievement of harmlessness and recovery of contaminated rice straw. |
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