生物质炭热解炭化条件及其性质的文献分析

【目的】因生物炭具有对土壤固碳减排和作物增产以及环境修复的作用，已受到国内外学者的广泛关注。本文回顾近年来生物质炭性质的相关研究，分析农业应用中生物质炭性质问题，阐述未来生物质炭性质研究发展趋势。【方法】收集了截至2015年12月文献出版物中402篇文献，对数据按生物质炭来源地区、生产 (制备) 条件和性质类别进行分类评价。【结果】1) 目前研究中应用的生物质炭68.2%为实验室制备，商业化生产比例只有22.9%；2) 生物质炭原料以林木为主，占44.3%，其次是农作物剩余物，占38.6%。作物秸秆制备的生物质炭以中国研究最多；3) 制备生物质炭的炭化温度范围在300～700℃ (91.4%)，400～600℃的温度范围以商业化生产中较常用；4) 生物质炭性质测定除总 (有机) 碳外，常测指标还包括pH、电导率、总氮、灰分和比表面积等，潜在污染物指标测定较少，而污泥炭中的重金属及植物源炭的多环芳烃潜在风险仍需研究；5) 生物质炭的研究制备原料基本上取决于该区域内可收集的废弃物，欧美地区主要关注林木生物质炭，亚洲等的发展中国家则着重研究秸秆生物质炭。【结论】与欧美国家相比，发展中国家的生物质炭商品化生产仍较薄弱。不同原料和温度生产的生物质炭性质和功能差别很大，以秸秆为原料、中温炭化的生物质炭各方面性质较为平衡，具备生物质炭大规模产业化的条件。此外，生物质炭性质的测试注重理化性状，对潜在风险污染物的分析普遍不足，亟需开发一个标准来规范生物质炭最小测试指标集和合适的测试方法选择。

Literature analysis on properties and pyrolyzing conditions of biochars

【Objectives】Application of biochar in agriculture has recently received great attention around the world for its potential to enhance carbon sequestration, crop productivity and environment quality of soils. This paper reviewed global literature on biochar study, analysed biochar property depended of the production conditions and explored future research needs.【Methods】Data were retrieved from 402 publications available by the end of 2015, and were categorized in terms of study location regions, production/preparation conditions and properties of biochars.【Results】1) The studied biochars were mainly prepared in lab (68.2%), while a minor portion (22.9%) commercially produced. 2) Both woods (44.3%) and crop residues (38.6%) were the main feedstocks, though biochars from China were more from crop residues. 3) Pyrolyzing temperature ranged mostly (71.3%) from 300℃ to 600℃, but more often between 400–600℃ with commercial production. 4) Among the properties tested for biochars, total organic carbon was the most frequently measured, and those of pH, EC, total nitrogen, ash content and specific surface area were often tested. While concentrations of potentially toxic contaminants of biochar were often ignored, the potential risk of PAHs in plant-derived biochar and heavy metals in sludge biochars is still to be studied. 5) In addition, most biochars were produced with feedstocks available in the study area, and measurements of biochar properties and the methods needed to be upgraded and standardized.【Conclusions】While global studies on biochar were progressively increasing, attentions were paid more on biochar from woods in European and America but from crop residues in the developing countries. Moreover, commercialized biochar production was less developed in the developing countries compared to the EU and US. There were vast differences in biochar properties and functions across feedstocks and production conditions. But biochar from crop straws or under medium pyrolyzing temperature was more or less balanced between the properties of various significance, which could be concerned as a commercial production scenario. In addition, there was limited knowledge of potentially toxic pollutants. Finally, a framework of a minimum set of biochar testing including properties and the applicable methods should be upgraded.