nZVI/BC与(Cu-Pd)/BC协同提高硝酸盐的去除和氮气的选择性

为探明纳米零价铁（nZVI）/BC与(Cu-Pd)/BC联合作用对水中硝酸盐的去除机理，分别负载纳米金属于小麦秸秆生物炭上，制得nZVI/BC与(Cu-Pd)/BC两种复合材料，并通过SEM、TEM、EDS、XRD对材料进行表征分析，从nZVI/BC的SEM中可以看出，纳米零价铁较好地分散在生物炭（BC）上面；从(Cu-Pd)/BC的TEM图中看出，纳米铜钯均有效地负载于BC上且分布均匀。结果表明，nZVI/BC:(Cu-Pd)/BC体系中硝酸盐的去除率可达100%，氮气转化率达到42%。当pH为4.05时硝酸盐去除效果最佳；硝酸盐去除率随着初始浓度的升高而降低；溶解氧的存在会降低硝酸盐去除率；存在PO{}_{\mathrm{4}}^{\mathrm{3}-}对去除效率的影响最大，去除率降低至15.8%，而CO{}_{\mathrm{3}}^{\mathrm{2}-}和SO{}_{\mathrm{4}}^{\mathrm{2}-}的存在对去除氮的影响不大，去除率接近100%。动力学研究表明：在最佳条件下，nZVI/BC与(Cu-Pd)/BC联合作用对NO{}_{\mathrm{3}}^{-}-N、NO{}_{\mathrm{2}}^{-}-N的去除均符合准二级吸附动力学模型，反应过程以还原反应为主。

Improvement of nitrate removal and nitrogen selectivity by the synergy of nZVI/BC and (Cu-Pd)/BC

To investigate the mechanism of nitrate removal from water by the combined action of nano zero-valent iron (nZVI)/BC and (Cu-Pd)/BC, nZVI/BC and (Cu-Pd)/BC composites were produced by loading nano-metals on wheat straw biochar, and the materials were characterized by SEM, TEM, EDS, and XRD. The results showed that the nano-zero valent iron was well dispersed on the biochar (BC) and the nano-Cu-Pd was effectively loaded on the BC with uniform distribution. The nitrate removal rate of nZVI/BC: (Cu-Pd)/BC systems could reach 100% and the nitrogen conversion rate reached 42%. The best nitrate removal was achieved at pH 4.05; nitrate removal decreased with increasing initial concentration; the presence of dissolved oxygen reduced the nitrate removal; the presence of PO{}_{\mathrm{4}}^{\mathrm{3}-} had the greatest effect on the removal efficiency and reduced the removal rate to 15.8%, while the presence of CO{}_{\mathrm{3}}^{\mathrm{2}-} and SO{}_{\mathrm{4}}^{\mathrm{2}-} had little effect on nitrogen removal and the removal rate was close to 100%. Kinetic studies showed that the removal of NO{}_{\mathrm{3}}^{-}-N and NO{}_{\mathrm{2}}^{-}-N by the combined action of nZVI/BC and (Cu-Pd)/BC under optimal conditions was in accordance with the quasi-secondary adsorption kinetic model, and the reaction process was dominated by the reduction reaction.