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金宝贞教授和伊丽莎白B教授的这一项目。天普大学的Cerkez和罗格斯大学纽瓦克分校的Evert J. Elzinga教授。该团队研究了金属杂质对锰（Mn）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。锰氧化物在工业中具有重要的应用，例如在电池、储能装置和传感器中。通过加入金属杂质可以改变其性质的矿物具有潜在的工业用途。该项目吸引了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做了演讲，为一个经常被忽视的人口群体带来了新的有趣的科学。该项目研究黑锰矿和锰锰矿，这是环境中分布最广的锰（II/III）氧化物。研究小组研究了金属杂质如何以及在多大程度上改变矿物的结构，反应性和稳定性。 他们还研究了各种反应过程中外来金属的潜在释放。黑锰矿和锰矿取代不同的微量金属类型（二价只有镍和锌对氧化还原活性的钴）和浓度（1和2重量%）测量As（III）的氧化能力和过渡金属的溶解度，以量化的取代效果。并与原生矿物的矿物学转变动力学进行了比较。采用各种最先进的分析技术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，并识别转化产物。该项目为金属杂质对锰矿物的结构，反应性和稳定性的影响提供了机理见解。该项目进一步突出了低价锰氧化物在自然环境中锰、微量金属和准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知识价值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.