Targeting the removal of Pb2+ in wastewater, sugarcane bagasse was treated with nitric acid and an alkaline solution to prepare adsorbents. On a typical adsorbent, the adsorption isotherms agreed well with the Langmuir expression, and the maximum adsorption capacity reached 200.3 mg/g. In the presence of 150 ppm Ca2+, a common cation in natural water, the Pb2+ adsorption capacity slightly declined. In contrast, Mg2+ obviously prohibited the adsorption for Pb2+. The spent adsorbent could be regenerated at least five times through elution with an EDTA solution. EDS and XPS results demonstrated that nitric acid functioned as an oxidant instead of nitrification agent in the treatment of bagasse. The adsorption process was consistent with quasi-second-order kinetics. Based on thermodynamic studies, the changes in enthalpy and Gibbs free energy were calculated to be - 33.3 and ca. - 18 kJ/mol, indicating that the adsorption process was exothermic and spontaneous. The equilibrium Pb2+ adsorption amounts were proportional to the numbers of carboxylate groups on different adsorbents. The binding energies of Pd 4f5/2 and Pd 4f7/2 XPS spectra of Pb2+ adsorbed were 0.6-0.7 eV lower than those of free Pb(NO3)2, indicating the transfer of electrons during adsorption. The conversion of hydroxymethyl groups in sugarcane bagasse into carboxylate groups, as well as the chelation between Pb2+ ions and carboxylate groups, was validated in this work, which is beneficial for the treatment of wastewater polluted by lead ions.

中文翻译：

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通过协同氧化和去质子化制备的功能化甘蔗渣上的铅离子吸附。

为了去除废水中的Pb2 +，将甘蔗渣用硝酸和碱性溶液处理以制备吸附剂。在典型的吸附剂上，吸附等温线与Langmuir表达式吻合得很好，最大吸附容量达到200.3 mg / g。在天然水中的常见阳离子150 ppm Ca2 +的存在下，Pb2 +的吸附容量略有下降。相反，Mg2 +明显禁止了Pb2 +的吸附。通过用EDTA溶液洗脱，用过的吸附剂可以再生至少五次。EDS和XPS结果表明，在蔗渣处理中，硝酸起氧化剂作用而不是硝化作用。吸附过程与准二级动力学一致。根据热力学研究，焓和吉布斯自由能的变化被计算为-33.3和ca。-18 kJ / mol，表明吸附过程是放热的和自发的。平衡的Pb2 +吸附量与不同吸附剂上羧酸根的数量成正比。吸附的Pb2 +的Pd 4f5 / 2和Pd 4f7 / 2 XPS光谱的结合能比游离Pb（NO3）2的结合能低0.6-0.7 eV，表明在吸附过程中电子转移。这项工作验证了甘蔗渣中的羟甲基转化为羧酸根，以及Pb2 +离子与羧酸根之间的螯合，这对于处理铅离子污染的废水是有利的。平衡的Pb2 +吸附量与不同吸附剂上羧酸根的数量成正比。吸附的Pb2 +的Pd 4f5 / 2和Pd 4f7 / 2 XPS光谱的结合能比游离Pb（NO3）2的结合能低0.6-0.7 eV，表明在吸附过程中电子转移。这项工作验证了甘蔗渣中的羟甲基转化为羧酸根，以及Pb2 +离子与羧酸根之间的螯合，这对于处理铅离子污染的废水是有利的。平衡的Pb2 +吸附量与不同吸附剂上羧酸根的数量成正比。吸附的Pb2 +的Pd 4f5 / 2和Pd 4f7 / 2 XPS光谱的结合能比游离Pb（NO3）2的结合能低0.6-0.7 eV，表明在吸附过程中电子转移。这项工作验证了甘蔗渣中的羟甲基转化为羧酸根，以及Pb2 +离子与羧酸根之间的螯合，这对于处理铅离子污染的废水是有利的。