Faculty of Chemistry, TNU-University of Science, Thai Nguyen City 24000, Vietnam.
School of Materials Science and Engineering, University of NSW, Kensington, NSW 2052, Australia.
Molecules. 2023 Feb 27;28(5):2225. doi: 10.3390/molecules28052225.
Soil heavy metal contamination is a severe issue. The detrimental impact of contaminated heavy metals on the ecosystem depends on the chemical form of heavy metals. Biochar produced at 400 °C (CB400) and 600 °C (CB600) from corn cob was applied to remediate Pb and Zn in contaminated soil. After a one month amendment with biochar (CB400 and CB600) and apatite (AP) with the ratio of 3%, 5%, 10%, and 3:3% and 5:5% of the weight of biochar and apatite, the untreated and treated soil were extracted using Tessier's sequence extraction procedure. The five chemical fractions of the Tessier procedure were the exchangeable fraction (F1), carbonate fraction (F2), Fe/Mn oxide fraction (F3), organic matter (F4), and residual fraction (F5). The concentration of heavy metals in the five chemical fractions was analyzed using inductively coupled plasma mass spectroscopy (ICP-MS). The results showed that the total concentration of Pb and Zn in the soil was 3023.70 ± 98.60 mg kg and 2034.33 ± 35.41 mg kg, respectively. These figures were 15.12 and 6.78 times higher than the limit standard set by the United States Environmental Protection Agency (U.S. EPA 2010), indicating the high level of contamination of Pb and Zn in the studied soil. The treated soil's pH, OC, and EC increased significantly compared to the untreated soil ( > 0.05). The chemical fraction of Pb and Zn was in the descending sequence of F2 (67%) > F5 (13%) > F1 (10%) > F3 (9%) > F4 (1%) and F2~F3 (28%) > F5 (27%) > F1 (16%) > F4 (0.4%), respectively. The amendment of BC400, BC600, and apatite significantly reduced the exchangeable fraction of Pb and Zn and increased the other stable fractions including F3, F4, and F5, especially at the rate of 10% of biochar and a combination of 5:5% of biochar and apatite. The effects of CB400 and CB600 on the reduction in the exchangeable fraction of Pb and Zn were almost the same ( > 0.05). The results showed that CB400, CB600, and the mixture of these biochars with apatite applied at 5% or 10% (/) could immobilize lead and zinc in soil and reduce the threat to the surrounding environment. Therefore, biochar derived from corn cob and apatite could be promising materials for immobilizing heavy metals in multiple-contaminated soil.
土壤重金属污染是一个严重的问题。受污染重金属对生态系统的有害影响取决于重金属的化学形态。从玉米芯中在 400°C（CB400）和 600°C（CB600）下制备的生物炭被应用于修复污染土壤中的 Pb 和 Zn。在用生物炭（CB400 和 CB600）和磷灰石（AP）以 3%、5%、10%和 3:3%、5:5%的比例和重量改性一个月后，未处理和处理过的土壤使用 Tessier 序列提取程序进行提取。Tessier 程序的五个化学部分是可交换部分（F1）、碳酸盐部分（F2）、Fe/Mn 氧化物部分（F3）、有机物部分（F4）和残余部分（F5）。使用电感耦合等离子体质谱法（ICP-MS）分析五个化学部分中重金属的浓度。结果表明，土壤中 Pb 和 Zn 的总浓度分别为 3023.70±98.60mg/kg 和 2034.33±35.41mg/kg，分别是美国环境保护署（U.S. EPA 2010）设定的限量标准的 15.12 和 6.78 倍，表明研究土壤中 Pb 和 Zn 的污染水平很高。处理过的土壤的 pH 值、OC 和 EC 与未处理的土壤相比显著增加（>0.05）。Pb 和 Zn 的化学部分按 F2（67%）>F5（13%）>F1（10%）>F3（9%）>F4（1%）和 F2~F3（28%）>F5（27%）>F1（16%）>F4（0.4%）的顺序递减。BC400、BC600 和磷灰石的添加显著降低了 Pb 和 Zn 的可交换部分，并增加了其他稳定部分，包括 F3、F4 和 F5，特别是在生物炭添加率为 10%和生物炭与磷灰石的比例为 5:5%时。CB400 和 CB600 对降低 Pb 和 Zn 的可交换部分的影响几乎相同（>0.05）。结果表明，CB400、CB600 和这些生物炭与磷灰石的混合物以 5%或 10%（/）的比例添加，可以固定土壤中的铅和锌，减少对周围环境的威胁。因此，玉米芯衍生的生物炭和磷灰石可以成为固定多种污染土壤中重金属的有前途的材料。
