ABSTRACT

Novel adsorbents that remove P from contaminated waters can be potentially used as slow release P-fertilizers. In this study, Mg-Al layered double hydroxide (Mg-Al-LDH) and Mg-Al-LDH functionalized apple wood biochar and hydrochar were prepared to remove phosphate from aqueous solutions and then P-loaded LDH-biochar/hydrochar composites used as fertilizers for maize production in calcareous soils under controlled conditions. After five successive desorption cycles, the LDH, LDH-biochar, and LDH-hydrochar desorbed 18, 22, and 27% of adsorbed-P into a 0.03 M KCl solution, respectively, while, these adsorbents desorbed 52, 63, and 66% of adsorbed-P into a 0.1 M Na₂CO₃ solution, respectively. Additionally, increasing solution pH from 3.0 to 10 increased P desorption. The results revealed that the P-loaded LDH-biochar and LDH-hydrochar significantly increased available-P, maize shoot and root dry matters, and P uptake as compared with control. The integration of monocalcium phosphate fertilizer with ‎biochar, hydrochar, LDH-biochar, and LDH-hydrochar increased available-P, ‎maize shoot and root dry matters, and P uptake; while P integration with P-loaded LDH-biochar/hydrochar decreased shoot dry matter. Therefore, the P-loaded LDH-biochar/hydrochar can be added to soil as P-fertilizers without any chemical P-fertilizer. Application of biochar, hydrochar, and LDH-biochar/hydrochar accompany with chemical P-fertilizers is recommended to increase available-P and maize growth.

摘要

从受污染的水中去除磷的新型吸附剂可用作缓释磷肥。在本研究中，制备了 Mg-Al 层状双氢氧化物 (Mg-Al-LDH) 和 Mg-Al-LDH 功能化的苹果木生物炭和水碳，以去除水溶液中的磷酸盐，然后将负载 P 的 LDH-生物炭/水碳复合材料用作在受控条件下用于石灰质土壤中玉米生产的肥料。经过五个连续的解吸循环后，LDH、LDH-生物炭和 LDH-hydrochar 分别将 18%、22% 和 27% 的吸附-P 解吸到 0.03 M KCl 溶液中，而这些吸附剂分别解吸了 52%、63% 和 66%吸附-P 到 0.1 M Na ₂ CO ₃解，分别。此外，将溶液 pH 从 3.0 增加到 10 会增加 P 解吸。结果表明，与对照相比，负载 P 的 LDH-biochar 和 LDH-hydrochar 显着增加了有效磷、玉米芽和根干物质以及磷的吸收。磷酸一钙肥料与生物炭、水炭、LDH-生物炭和LDH-水炭的结合增加了有效磷、玉米芽和根干物质以及磷的吸收；而 P 与负载 P 的 LDH-biochar/hydrochar 整合减少了地上部干物质。因此，加载 P 的 LDH-biochar/hydrochar 可以作为 P 肥料添加到土壤中，无需任何化学 P 肥料。建议将生物炭、水炭和 LDH-生物炭/水炭与化学磷肥一起使用，以增加有效磷和玉米的生长。