Collaborative Research: Effects of Structural Impurities on the Reactivity and Transformation of Lower Valent Manganese Oxides

化学系的环境化学科学项目支持由坦普尔大学的金博正教授和伊丽莎白·B·切尔凯兹教授以及纽瓦克罗格斯大学的埃弗特·J·埃尔津加教授开展的这一项目。该团队调查了金属杂质对锰(锰)氧化物的结构、反应性和稳定性的影响。天然锰氧化物通常含有一系列杂质，但这些杂质对化学反应和矿物转化的影响尚不清楚。锰氧化物在工业上有重要的应用，如在电池、储能设备和传感器方面。矿物有潜在的工业用途，其性质可以通过包括金属杂质来改变。该项目面向坦普尔大学和罗格斯大学的研究生和本科生。该团队向费城地区的退休社区发表演讲，为经常被忽视的人口群体带来了新的有趣的科学。该项目研究了环境中分布最广泛的锰(II/III)氧化物--黑锰矿和锰矿。研究小组研究了金属杂质如何以及在多大程度上改变了矿物的结构、反应性和稳定性。他们还检查了在各种反应中可能释放的外来金属。用不同的微量金属类型(二价镍和锌与氧化还原活性的钴)和浓度(1和2wt%)取代的豪斯锰矿和锰矿，测定了As(III)的氧化能力和过渡金属的溶解度，以量化取代的影响。并与原生矿物的矿物学转化动力学进行了对比。各种最先进的分析技术被用来表征金属取代基的配位化学和价态，探测界面氧化还原化学，并鉴定转化产物。该项目提供了对金属杂质对锰矿物的结构、反应性和稳定性的影响的机械见解。该项目进一步强调了低价锰氧化物在自然环境中锰、痕量金属和类金属的地球化学循环中的作用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The Environmental Chemical Science Program in the Chemistry Division supports this project by Professors Bojeong Kim and Elizabeth B. Cerkez at Temple University and Professor Evert J. Elzinga at Rutgers University-Newark. The team investigates the effects of metal impurities on the structure, reactivity, and stability of manganese (Mn) oxides. Natural Mn oxides typically contain a range of impurities, but the impact of these impurities on the chemical reactions and mineral transformations are unknown. Mn oxides have important applications in industry, such as in batteries, energy storage devices, and sensors. There are potential industrial uses of minerals whose properties could be changed by including metal impurities. This project engages graduate and undergraduate students at both Temple and Rutgers Universities. The team makes presentations to retirement communities in the Philadelphia area, which brings new and interesting science to an often-overlooked demographic group. This project examines hausmannite and manganite, the most widely distributed Mn(II/III) oxides in the environment. The research team examines how and to what extent metal impurities alter the minerals’ structure, reactivity, and stability. They also examine the potential release of foreign metals during various reactions. Hausmannite and manganite substituted with varying trace metal types (divalent-only Ni and Zn versus redox-active Co) and concentrations (1 and 2 wt%) are measured for As(III) oxidizing ability and transition metal solubility to quantify the substitution effects. The mineralogical transformation kinetics in substituted minerals are also compared with pristine minerals. A variety of state-of-the-art analytical techniques are employed to characterize the coordination chemistry and valence of metal substituents, probe interfacial redox chemistry, and identify transformation products. The project provides mechanistic insights into the effects of metal impurities on the structure, reactivity, and stability of Mn minerals. The project further highlights the role of the lower valent Mn oxides in the geochemical cycling of Mn, trace metals, and metalloids in natural environments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.