Department of Agricultural Engineering, Cairo University, Giza, Egypt; Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Department of Chemical and Biological Engineering, University of British Columbia, Vancouver, BC V6T 1Z3, Canada.
Chemosphere. 2021 May;271:129808. doi: 10.1016/j.chemosphere.2021.129808. Epub 2021 Jan 30.
Pb, Ni, and Co are among the most toxic heavy metals that pose direct risks to humans and biota. There are no published studies on biochars produced at low temperatures (i.e., 300 °C), which possess high sorption capacity for heavy metal remediation and reclamation of contaminated sandy soils. This research studied the effect of catalytic microwave pyrolysis of switchgrass (SG) using bentonite and KPO to produce biochar at low temperature (300 °C) with high sorption capacity for reducing the phytotoxicity of heavy metals, and investigated the synergistic effects of catalyst mixture on biochar sorption capacity. The quality of the biochars was examined in terms of their impacts on plant growth, reducing phytotoxicity and uptake of heavy metals in sandy soil spiked with Pb, Ni, and Co. All catalysts increased the micropore surface area and cation-exchange capacity of biochars, and resulted in biochars rich in plant nutrients, which not only decreased heavy metal phytotoxicity, but also boosted plant growth in the spiked soil by up to 140% compared to the sample without biochar. By mixing bentonite and KPO with SG during microwave pyrolysis, the efficacy of biochar in reducing phytotoxicity and heavy metals uptake was further enhanced because of the highest micropore surface area (402 m/g), moderate contents of Ca, Mg, K, and Fe for ion-exchange and moderate concentration of phosphorus for the formation of insoluble heavy metal compounds. Generally, the biochar created at 300 °C (300-30KP) showed similar performance to the biochar created at 400 °C (400-30KP) in terms of reducing heavy metal bioavailability.
铅、镍和钴是毒性最大的重金属之一，对人类和生物群直接构成威胁。目前还没有关于在低温（即 300°C）下生产的生物炭的研究，而这些生物炭具有很高的重金属吸附能力，可用于修复和开垦受污染的沙质土壤。本研究使用膨润土和 KPO 对柳枝稷进行催化微波热解，在低温（300°C）下生产具有高吸附能力的生物炭，以减少重金属的植物毒性，并研究催化剂混合物对生物炭吸附能力的协同作用。根据生物炭对植物生长、降低重金属在添加 Pb、Ni 和 Co 的沙质土壤中的植物毒性和吸收的影响，考察了生物炭的质量。所有催化剂都增加了生物炭的微孔表面积和阳离子交换容量，并且使生物炭富含植物养分，这不仅降低了重金属的植物毒性，而且与不含生物炭的土壤相比，使添加土壤中的植物生长增加了 140%。通过在微波热解过程中用 SG 混合膨润土和 KPO，由于微孔表面积最高（402 m/g）、Ca、Mg、K 和 Fe 的离子交换含量适中以及形成不溶性重金属化合物的磷浓度适中，生物炭在降低植物毒性和重金属吸收方面的效果得到进一步增强。一般来说，在 300°C（300-30KP）下制备的生物炭在降低重金属生物有效性方面与在 400°C（400-30KP）下制备的生物炭具有相似的性能。
