Lkhamtogmid Nyamjargal, Gunchin Burmaa, Dashdendev Burmaa, Punsantsogvoo Munkhbaatar, Bat-Amgalan Munkhpurev, Yunden Ganchimeg
Department of Chemical Engineering, School of Applied Sciences, Mongolian University of Science and Technology, Ulaanbaatar 14191, Mongolia.
The Institute of Chemistry and Chemical Technology, Mongolian Academy of Sciences, Ulaanbaatar 13330, Mongolia.
Polymers (Basel). 2025 Jul 11;17(14):1914. doi: 10.3390/polym17141914.
This study investigates the potential of sulfuric acid modified wheat straw, polysaccharide-rich agricultural byproduct, as a low-cost adsorbent for the selective adsorption of Au(III) ions from aqueous solutions. The wheat straw was treated with concentrated sulfuric acid to enhance its surface properties and functional groups, particularly sulfonic and oxygen-containing functional groups. Adsorption experiments were performed under various conditions, including acid concentrations ranging from 1.0 to 3.0 mol/L, contact times from 1 to 6 h, and initial Au(III) concentrations of 60.36, 90.0, and 150.0 mg/L. The highest adsorption efficiency, 99.0%, was achieved at an acid concentration of 1.0 mol/L. Furthermore, it was determined that an increase in the initial Au(III) concentration from 60.36 mg/L to 150.0 mg/L resulted in a 4.5 times increase in maximum adsorption capacity under optimal conditions. Kinetic modeling revealed that the adsorption process followed pseudo-second order kinetics, suggesting chemisorption as the rate-limiting step. Characterization techniques such as SEM/EDS, XRD, BET and XPS confirmed structural modification, surface sulfonating, and the successful adsorption and reduction of Au(III) to elemental gold (Au) on the modified straw surface. This work demonstrates that modified wheat straw is a promising, effective, and low cost for the recovery of gold from low-concentration solutions and provides insight into the adsorption and reduction mechanisms at the molecular level.
本研究考察了硫酸改性的富含多糖的农业副产品小麦秸秆作为低成本吸附剂从水溶液中选择性吸附Au(III)离子的潜力。用浓硫酸处理小麦秸秆以增强其表面性质和官能团，特别是磺酸基和含氧官能团。在各种条件下进行吸附实验，包括酸浓度范围为1.0至3.0 mol/L、接触时间为1至6小时以及初始Au(III)浓度为60.36、90.0和150.0 mg/L。在酸浓度为1.0 mol/L时实现了最高吸附效率99.0%。此外，确定在最佳条件下，初始Au(III)浓度从60.36 mg/L增加到150.0 mg/L导致最大吸附容量增加4.5倍。动力学建模表明吸附过程遵循准二级动力学，表明化学吸附是限速步骤。扫描电子显微镜/能谱仪（SEM/EDS）、X射线衍射仪（XRD）、比表面积分析仪（BET）和X射线光电子能谱仪（XPS）等表征技术证实了改性秸秆表面的结构改性、表面磺化以及Au(III)成功吸附并还原为元素金（Au）。这项工作表明改性小麦秸秆对于从低浓度溶液中回收金是一种有前景、有效且低成本的材料，并在分子水平上深入了解了吸附和还原机制。
