Every year, hundreds of millions of tons of straw are produced by wheat planting all over the world. In this work, a potential method using wheat straw to produce magnetic sorbents for soil Cd extraction was studied. Wheat straw chips were pyrolyzed at 300 and 700 °C and then mixed with Fe³⁺/Fe²⁺ solution for magnetization. The obtained magnetically modified biochars (MMBs) were applied to two Cd-contaminated paddy soils. During a 30-day experiment, MMB recovery from soils by a magnetic rod decreased over time, ranging from 62% to 100% for MMB300 and from 36% to 65% for MMB700. At the end, extraction efficiency of Cd from soils by the MMBs ranged from 21.5% to 31.5%, which was related to sorption capacity of Cd by MMB, recovery percentage of MMB from soils and distribution of Cd fractions in soils. Cd in the exchangeable fraction was more easily extracted by the MMBs (46–78%) than the other Cd fractions. Furthermore, extracting Cd from soils by the MMBs reduced Cd concentration in ryegrass by about 70%, which was largely related to the decrease of soil exchangeable fraction. These findings demonstrate the efficient remediation of Cd-contaminated soils by MMB extraction and meanwhile provide some guidance for further optimization of MMB properties.

每年，全世界的小麦种植都会产生数亿吨的稻草。在这项工作中，研究了一种潜在的方法，该方法利用小麦秸秆生产用于吸附土壤镉的磁性吸附剂。将麦草屑在300和700°C下热解，然后与Fe ³⁺ / Fe ²⁺混合磁化解决方案。将获得的磁性改性生物炭（MMB）应用于两种受Cd污染的稻田土壤。在为期30天的实验中，磁棒从土壤中回收的MMB随着时间的推移而下降，MMB300的回收率从62％降低到100％，MMB700的回收率从36％降低到65％。最后，MMBs从土壤中萃取Cd的效率在21.5％至31.5％之间，这与MMB对Cd的吸附能力，MMB在土壤中的回收率以及Cd在土壤中的分布有关。MMBs（46-78％）比其他Cd馏分更容易提取可交换馏分中的Cd。此外，通过MMBs从土壤中提取Cd可使黑麦草中的Cd浓度降低约70％，这在很大程度上与土壤可交换分数的降低有关。