Metal oxide-loaded biochars are a promising material to remove phosphate from polluted water to ultra-low concentrations. To facilitate preparing the metal oxide-loaded biochar with the best phosphate adsorption performance, five biochars loaded with Al, Ca, Fe, La and Mg oxides, respectively (Al-BC, Ca-BC, Fe-BC, La-BC and Mg-BC) were produced using Phragmites australis pretreated with 0.1 mol AlCl₃, CaCl₂, FeCl₃, LaCl₃ and MgCl₂, respectively, characterized, and phosphate adsorption kinetics and isotherms of the biochars were determined. The maximum phosphate adsorption capacities (Q_m) of the biochars ranked as Al-BC (219.87 mg g⁻¹) > Mg-BC (112.45 mg g⁻¹) > Ca-BC (81.46 mg g⁻¹) > Fe-BC (46.61 mg g⁻¹) > La-BC (38.93 mg g⁻¹). The time to reach the adsorption equilibrium ranked as La-BC (1 h) < Ca-BC (12 h) < Mg-BC (24 h) = Fe-BC (24 h) <Al-BC (greater than 72 h). Q_m of Ca-BC, Fe-BC, La-BC and Mg-BC depend on the molar content of metals in the biochars. The small phosphate adsorption rate of Al-BC is due to the slow intra-particle diffusion of phosphate attributed to the undeveloped porosity and dispersed distribution of AlOOH crystals on the Al-BC surface. Mg-BC is suggested for phosphate removal from water considering adsorption rate and capacity. Al-BC is applicable when a long contact time is allowed, e.g. as a capping material to immobilize phosphate in lake sediments.

负载金属氧化物的生物炭是一种很有前途的材料，可以将污水中的磷酸盐去除至超低浓度。为了便于制备具有最佳磷酸盐吸附性能的负载金属氧化物的生物炭，分别负载有 Al、Ca、Fe、La 和 Mg 氧化物的五种生物炭（Al-BC、Ca-BC、Fe-BC、La-BC 和 Mg -BC) 使用分别用 0.1 mol AlCl ₃、CaCl ₂、FeCl ₃、LaCl ₃和 MgCl ₂预处理的芦苇生产，表征，并确定了生物炭的磷酸盐吸附动力学和等温线。生物炭的最大磷酸盐吸附容量 ( Q _m ) 列为 Al-BC (219.87 mg g^-1 ) > Mg-BC (112.45 mg g ^-1 ) > Ca-BC (81.46 mg g ^-1 ) > Fe-BC (46.61 mg g ^-1 ) > La-BC (38.93 mg g ^-1 )。达到吸附平衡的时间排列为 La-BC (1 h) < Ca-BC (12 h) < Mg-BC (24 h) = Fe-BC (24 h) < Al-BC (大于 72 h) . Q_米Ca-BC、Fe-BC、La-BC 和 Mg-BC 的含量取决于生物炭中金属的摩尔含量。Al-BC 的磷酸盐吸附率小是由于磷酸盐的颗粒内扩散缓慢，这是由于 Al-BC 表面上未开发的孔隙率和 AlOOH 晶体的分散分布。考虑到吸附速率和容量，建议使用 Mg-BC 从水中去除磷酸盐。当允许长时间接触时，Al-BC 适用，例如作为将磷酸盐固定在湖泊沉积物中的封盖材料。