In order to reduce sewage sludge of concentrated natural rubber latex (CNRL) and transform it into a valuable material for efficient removal of Al³⁺ and Cu²⁺ ions from wastewater, magnetic biochar was prepared. In this work, sewage sludge from CNRL was pyrolyzed at various temperatures (300–700 °C) to assess the effects of pyrolysis temperature on the efficiency of magnetic biochar in removing Al³⁺ and Cu²⁺ ions from an aqueous medium. Effect of the chemical composition of sewage sludge on the biochar characteristic was evaluated. Sewage sludge is mainly organic matter. The mineral elements silicon (Si), phosphorus (P), sulfur (S) and calcium (Ca) were also observed in the sewage sludge. With increasing pyrolysis temperature, the contents of P and potassium (K) increased. The inorganic metals chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni) and lead (Pb) were present in small quantities. Pyrolysis temperatures 400–500 °C provided good quality magnetic biochar, while with the higher 700 °C pyrolysis temperature, specific surface area and pore volume decreased. The prepared biochar had combined meso- and macro-porous structure. Isotherms of Type II were indicating multilayer adsorption on porous biochar. The pseudo-second-order kinetic models described well Al³⁺ and Cu²⁺ adsorption onto magnetic biochar. The leaching test of magnetic biochar shows the releasing of K and Zinc (Zn) which can effect on the sorption of Al³⁺ and Cu²⁺. The binding mechanism between magnetic biochar and Al³⁺/Cu²⁺ involved surface complexation, ion exchange and cation‒π interaction.

中文翻译：

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浓缩天然胶乳（CNRL）污水污泥中产生的磁性生物炭，用于去除废水中的Al 3+和Cu 2+离子

为了减少浓缩天然胶乳（CNRL）的污水污泥并将其转化为有效去除废水中Al ³⁺和Cu ²⁺离子的有价值的材料，制备了磁性生物炭。在这项工作中，来自CNRL的污水污泥在各种温度下（300-700°C）进行热解，以评估热解温度对磁性生物炭去除Al ³⁺和Cu ²⁺效率的影响。来自水性介质的离子。评价了污水污泥的化学组成对生物炭特性的影响。污水污泥主要是有机物。在污水污泥中还观察到了矿物元素硅（Si），磷（P），硫（S）和钙（Ca）。随着热解温度的升高，P和钾（K）的含量增加。少量存在无机金属铬（Cr），铜（Cu），锰（Mn），镍（Ni）和铅（Pb）。热解温度为400–500°C可提供高质量的磁性生物炭，而较高的700°C热解温度可降低比表面积和孔体积。制备的生物炭具有中孔和大孔结构的组合。II型等温线表明在多孔生物炭上有多层吸附。³⁺和Cu ²⁺吸附到磁性生物炭上。磁性生物炭的浸出试验表明，钾和锌（Zn）的释放会影响Al ³⁺和Cu ²⁺的吸附。磁性生物炭与Al ³⁺ / Cu ²⁺的结合机理涉及表面络合，离子交换和阳离子π相互作用。