Material properties and environmental potential of developing world-derived biochar made from common crop residues
Material properties and environmental potential of developing world-derived biochar made from common crop residues
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DOI：
10.1016/j.envc.2021.100137
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发表时间：
2021-08
期刊：
影响因子：
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通讯作者：
Nathan L. Howell;Andy Pimentel;S. Bhattacharia
中科院分区：
文献类型：
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作者：
Nathan L. Howell;Andy Pimentel;S. Bhattacharia
生物炭通常采用高科技、高控制的方法制造，毫无疑问，这将更好地优化最终材料，使其达到预期目的，并增加其价值。相比之下，我们使用低技术、低控制的方法，从两种常见的作物废料——棉籽（CS）和山核桃壳（PS）——生产了发展中国家的生物炭（DWB）。我们使用由油漆罐制成的顶部照明上升气流微气化炉（TLUD）创建了DWB生物炭，并将其与在450°C （MF450）的马弗炉中创建的生物炭进行了比较。我们首先使用现代材料表征方法（产率，BET, SEM/EDS， TGA， XRD， FTIR）来了解原料上生物炭生产方法的差异。然后，我们使用阳离子和阴离子染料（甲基橙，MO和结晶紫，CV）的批量平衡吸附来检测环境性能。TLUD方法的生物炭产量通常比MF450低，因为我们认为TLUD中的大部分材料达到450°C左右的温度，有时难以保留在设备中。TLUD装置中的较高温度导致生物炭具有更多的微孔，具有更大的表面积，具有更少的表面官能团，具有更高的灰分含量，更碳化，并且具有更低的残余纤维素结晶度。在吸附性能上存在差异，MF450生物炭对CV的吸附比TLUD更强。对于MO， PS-TLUD对染料的吸附效果不如PS-MF450，而CS-TLUD的吸附强度远高于CS-MF450。我们不确定为什么这两种方法在不同的原料中表现出相反的效果，但推测这可能与PS-TLUD中的矿物质含量比MF450高得多有关。在研究过的许多等温线中，Freundlich和Langmuir等温线只在一半的情况下与我们的数据最吻合。有时s型等温线是最适合的，或者仍然相当适合数据。与其他研究相比，DWB对染料的吸附效果并不好，但在相关的环境染料浓度下，DWB仍能有效去除染料。总的来说，我们得出结论，以这种不受控制的方式制造的DWB可以根据材料特性和环境性能制造出相当高质量的生物炭。我们建议对其他低技术含量的生物炭生产方法进行额外的研究，以了解如何根据发展中国家社区的预期用途扩大和优化它们。
Biochar is frequently made using high-tech, high-control methods which will no doubt better optimize the final material for its intended purpose and increase its value. In contrast, we used low-tech, low-control methods to produce a developing world biochar (DWB) from two common crop wastes, cottonseed (CS) and pecan shell (PS). We created DWB biochar using a top-lit updraft microgasifier (TLUD) made from paint cans, and compared it to a biochar created in a muffle furnace held at 450 °C (MF450). We first used modern material characterization methods (yield, BET, SEM/EDS, TGA, XRD, FTIR) to understand the difference in biochar production methods on the feedstock. We then used batch equilibrium adsorption with cationic and anionic dyes (methyl orange, MO and crystal violet, CV) to examine environmental performance. The TLUD method generally has a lower biochar production yield than MF450 because we believe much of the material in the TLUD achieves temperatures > 450 °C and is sometimes difficult to retain in the device. The higher temperatures in the TLUD device lead to a biochar which is more microporous, has greater surface area, has less surface functional groups, has greater ash content, is more carbonized, and has lower residual cellulose crystallinity.There were differences in adsorption performance whereby the MF450 biochar adsorbs CV more strongly than the TLUD. For MO, PS-TLUD is less effective at adsorbing the dye when compared to PS-MF450, while CS-TLUD has a much higher adsorption strength than CS-MF450. We are not certain why the two methods show opposite effects in different feedstock but speculate that it may have to do with the much higher mineral content in the PS-TLUD compared to its MF450 counterpart. Out of many isotherms examined Freundlich and Langmuir isotherms provide a best-fit to our data only about half the time. Sometimes an S-shaped isotherm was the best fit or still fit the data reasonably well. Comparing the dye adsorption to other studies, the DWB does not adsorb as well, yet it is still effective for removal at environmental dye concentrations of relevance. Overall, we conclude that DWB, made in this uncontrolled fashion, can make a reasonably high quality biochar based on material properties and environmental performance. We suggest that additional research be done on other low-tech biochar production methods to see how to scale-up and optimize them according a developing world community's intended use.