The function of biochar (BC) as an eco-friendly adsorbent for environmental remediation is gaining much attention. However, the pristine BC had limited abilities for the removal of As (III, V). Towards this issue, this study synthesized biochar/micro-nanosized α-MnO₂ (BM) composites with different mass ratios of biochar to MnO₂. Comprehensive characterizations confirmed the successful loading of micro-nanosized α-MnO₂ onto the BC surface and the obvious specific surface area enhancement (7.5–13.5 times) of BM relative to BC. BM composites exhibited 5.0–13.0 folds higher removal capacity for As (III, V) than pristine BC since the composites gave full play to the oxidation contributed by micro-nanosized α-MnO₂ substrate and adsorption functions provided by the Mn-OH, BC-COOH, and BC-OH functional groups. Moreover, BM was well reused maintaining a relatively high removal efficiency for As (III, V). Regardless of reaction time and initial As (III) concentration (C₀), the removal of As (III) by pristine BC was negligibly contributed by the oxidized As (V) remaining in solutions, with the relative contribution <15.0%. For the BM composites, relative contribution of adsorbed As (III, V) dominated over that of oxidation to mobile As (V) remaining in solution, and exhibited the decreasing trend with increasing C₀. These findings demonstrated BM as a promising candidate in remediating As (III, V)-polluted water, and provide mechanistic insights into the role of oxidation and adsorption in As (III, V) removal.

生物炭（BC）作为一种用于环境修复的环保吸附剂的功能受到越来越多的关注。然而，原始 BC 去除 As (III, V) 的能力有限。针对这个问题，本研究合成了具有不同生物炭与MnO ₂质量比的生物炭/微纳米α-MnO ₂ (BM)复合材料。综合表征证实了微纳米尺寸的α-MnO ₂成功加载到BC表面，并且BM相对于BC的比表面积明显增加（7.5-13.5倍）。BM 复合材料对 As (III, V) 的去除能力比原始 BC 高 5.0-13.0 倍，因为复合材料充分发挥了微纳米 α-MnO ₂的氧化作用Mn-OH、BC-COOH 和 BC-OH 官能团提供的底物和吸附功能。此外，BM 被很好地再利用，保持了对 As (III, V) 的相对较高的去除效率。不管反应时间和初始 As (III) 浓度 ( C ₀ )，原始 BC 对 As (III) 的去除对残留在溶液中的氧化 As (V) 的贡献可忽略不计，相对贡献 <15.0%。对于 BM 复合材料，吸附 As (III, V) 的相对贡献大于氧化对残留在溶液中的移动 As (V) 的贡献，并且随着C _{0 的}增加呈现下降趋势. 这些发现表明 BM 是修复 As (III, V) 污染水的有希望的候选者，并提供了对氧化和吸附在 As (III, V) 去除中的作用的机理见解。