Abstract This article experiments wetland-based biochar as an effective adsorbent for phosphorus removal. In this experiment, four common wetland plants, canna (C), umbrella palm (U), bamboo reed (B), and Thalia dealbata (T), were used as the main raw materials. Twelve kinds of biochar (C300, C500, C700, U300, U500, U700, B300, B500, B700, T300, T500, and T700) were obtained at three pyrolysis temperatures (300°C, 500°C, and 700°C). The results show that canna (C) and umbrella palm (U) are more suitable as raw materials for phosphorus removal using biochar. If bamboo reed (B) and Thalia dealbata (T) are used as raw materials for phosphorus removal using biochar, there is a greater risk of phosphorus release. With the increase of pyrolysis temperature (700°C > 500°C > 300°C), there is an increasing trend of phosphorus adsorption effect. The theoretical maximum adsorption capacity of C700, U700, and C500 was 39.24, 7.08, and 7.26 mg P·g−1 at an initial concentration of 50 mg·L−1 phosphorus, respectively. The theoretical adsorption capacity of C700 (Q max = 39.24 mg P·g−1) was much higher than that of the general modified adsorption materials. It also has a larger tolerance range to pH (3–11). The results of kinetic model fitting showed that the adsorption mechanism of C700, U700, and C500 on phosphorus can be better simulated by intra-particle diffusion and Elovich model, and the adsorption mechanism includes surface adsorption and intra-particle diffusion. The fitting of isothermal adsorption model showed that Langmuir–Freundlich equation is more suitable for the description of adsorption characteristics of C700, U700, and C500, and the fitting coefficient R 2 is 0.9928, 0.9949, and 0.9897, respectively. It indicates that the adsorption of phosphorus on C700, U700, and C500 has a balance of uniform and nonuniform surface, and monolayer and multilayer adsorption could occur. The results from this work demonstrated that the biochar obtained from canna at 700°C has good adsorption and phosphorus removal potential without modification, and it can be used as the preferred biochar for phosphorus removal of high concentration with large pH changes. In the final validation experiment, the phosphorus removal rate of C700 was up to 77.4% on the treatment of actual phosphorus containing wastewater.

中文翻译：

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湿地生物炭吸附去除水溶液中的磷：批量实验

摘要 本文对基于湿地的生物炭作为一种有效的除磷吸附剂进行了实验。本实验以四种常见的湿地植物美人蕉（C）、伞形棕榈（U）、竹苇（B）和塔利亚（T）为主要原料。在三个热解温度（300°C、500°C 和 700°C）下获得了 12 种生物炭（C300、C500、C700、U300、U500、U700、B300、B500、B700、T300、T500 和 T700） . 结果表明，美人蕉（C）和伞形棕榈（U）更适合作为生物炭除磷的原料。如果使用竹苇（B）和Thalia debata（T）作为生物炭除磷的原料，则存在较大的磷释放风险。随着热解温度的升高（700°C > 500°C > 300°C），磷吸附效果有增加的趋势。C700、U700和C500在初始磷浓度为50 mg·L-1时的理论最大吸附量分别为39.24、7.08和7.26 mg P·g-1。C700的理论吸附容量（Q max = 39.24 mg P·g-1）远高于一般改性吸附材料。它对 pH 值 (3–11) 的耐受范围也更大。动力学模型拟合结果表明，C700、U700和C500对磷的吸附机理可以通过颗粒内扩散和Elovich模型更好地模拟，吸附机理包括表面吸附和颗粒内扩散。等温吸附模型拟合表明，Langmuir-Freundlich方程更适合描述C700、U700和C500的吸附特性，拟合系数R 2 分别为0.9928、0.9949和0.9897。说明C700、U700和C500对磷的吸附在均匀和不均匀的表面之间存在平衡，可以发生单层和多层吸附。研究结果表明，700℃美人蕉生物炭未经修饰具有良好的吸附和除磷潜力，可作为高浓度、大pH值除磷的首选生物炭。在最终的验证实验中，C700的除磷率高达77。