Periodic Reporting for period 3 - CRYSTAL CLEAR (CRYSTAL CLEAR: determining the impact of charge on crystal nucleation)
Berichtszeitraum: 2022-04-01 bis 2023-09-30
With her ERC Consolidator Grant entitled ‘CRYSTAL CLEAR’, Dr Mariëtte Wolthers plans to research how minerals are formed under natural conditions. Up until now, experiments were nearly always conducted under ideal laboratory conditions, which meant that it was not possible to make direct comparisons with natural mineral formation. The research does not only have practical applications, but it could also change our understanding of how terrestrial minerals are formed.
Minerals form from tiny positively and negatively charged building blocks – ions – that coagulate and stick to each other in three-dimensional patterns. The initial steps in this process take place in water, at a scale so small that it can only be witnessed using an electron microscope, for example. Scientists have been experimenting with creating minerals for years, working in their laboratories with the ideal ratio of positive to negative building blocks. However, natural minerals rarely develop under these ideal circumstances. The ratio of positively to negatively charged ions can sometimes differ by up to a million.
Charge is key
With her ERC Consolidator Grant, Dr Mariëtte Wolthers will conduct laboratory experiments forming minerals at these skewed ratios. “A surplus of positive or negative building blocks causes a charge surplus or shortage”, explains Wolthers. “That can have a huge impact on how the minerals crystallise, and how quickly. I will therefore measure the charge and determine how it influences the crystallisation process. I subsequently plan to summarise the results in a new crystallisation law, in which I will work far beyond the boundaries of the earth sciences. I like to build bridges between different disciplines; this research is grounded in earth sciences, while it hinges on theoretical physics and computational chemistry’.
Minerals outlining the history of earth
“I also want to explore whether the new crystallisation law applies in natural settings”, continues Wolthers. “Based on our current understanding, we expect minerals to form in nature, while they often form very differently, or not at all. Current understanding is still based on the laboratory experiments conducted under ideal conditions. There is a strong chance that the skewed ratios play a significant role in this respect”.
The results from CRYSTAL CLEAR will help earth scientists to determine which rocks and minerals were formed where, how quickly they were formed and under which conditions. This could potentially dramatically impact our perspective of the history of earth, as this perspective was largely shaped by studying the characteristics of minerals.
Mineral formation in practice
A more practical application of the results of Wolthers’ research is in the use of geothermal energy, for example. In this process, warm water is pumped up from deep in the earth. When water pipes are located four kilometres underground, minimal maintenance is preferable. If we learn how to control mineral formation at such depths, we could take measures to reduce limestone formation, meaning that water pipes are less likely to become blocked.
Minerals form from tiny positively and negatively charged building blocks – ions – that coagulate and stick to each other in three-dimensional patterns. The initial steps in this process take place in water, at a scale so small that it can only be witnessed using an electron microscope, for example. Scientists have been experimenting with creating minerals for years, working in their laboratories with the ideal ratio of positive to negative building blocks. However, natural minerals rarely develop under these ideal circumstances. The ratio of positively to negatively charged ions can sometimes differ by up to a million.
Charge is key
With her ERC Consolidator Grant, Dr Mariëtte Wolthers will conduct laboratory experiments forming minerals at these skewed ratios. “A surplus of positive or negative building blocks causes a charge surplus or shortage”, explains Wolthers. “That can have a huge impact on how the minerals crystallise, and how quickly. I will therefore measure the charge and determine how it influences the crystallisation process. I subsequently plan to summarise the results in a new crystallisation law, in which I will work far beyond the boundaries of the earth sciences. I like to build bridges between different disciplines; this research is grounded in earth sciences, while it hinges on theoretical physics and computational chemistry’.
Minerals outlining the history of earth
“I also want to explore whether the new crystallisation law applies in natural settings”, continues Wolthers. “Based on our current understanding, we expect minerals to form in nature, while they often form very differently, or not at all. Current understanding is still based on the laboratory experiments conducted under ideal conditions. There is a strong chance that the skewed ratios play a significant role in this respect”.
The results from CRYSTAL CLEAR will help earth scientists to determine which rocks and minerals were formed where, how quickly they were formed and under which conditions. This could potentially dramatically impact our perspective of the history of earth, as this perspective was largely shaped by studying the characteristics of minerals.
Mineral formation in practice
A more practical application of the results of Wolthers’ research is in the use of geothermal energy, for example. In this process, warm water is pumped up from deep in the earth. When water pipes are located four kilometres underground, minimal maintenance is preferable. If we learn how to control mineral formation at such depths, we could take measures to reduce limestone formation, meaning that water pipes are less likely to become blocked.
In this project, we will test the hypothesis that ionic ratio has a dramatic impact on nucleation: crystals will be charged, and this charge will determine their size, how and how fast they grow, aggregate, and transform.
In the laboratory, we synthesise the minerals under different ratios of their building blocks. We measure how long it takes for crystals to form, how large they are, if and how they grow or aggregrate with time. We will also measure if the particles are charged, and how this evolves with time. Simultaneously, we investigate the crystal structure of the particles formed: are they amorphous (glass-like) or crystalline? Which crystal structure and does this remain constant with time? We will also visualise the sizes and shapes of the particles. If we unravel how sizes, shapes and crystallinity change with the ratio of their building blocks, we will generate a better “dictionary” for reading mineral textures in the geological archive: how were which mineral textures formed, so what were the environmental conditions at the time of mineral formation? We will then also provide new ways to tailor crystal formation for geo-enginering and industrial/pharamceutical purposes.
Besides laboratory work, we will simulate particle characteristics and formation processes. With these simulation results, we will obtain information at the molecular scale. In this way, we will derive charged-nuclei stability and surrounding water properties. The results will be combined into a new crystal nucleation theory, which can be used to predict or optimatize crystal formation processes in natural and engineered environments.
In the laboratory, we synthesise the minerals under different ratios of their building blocks. We measure how long it takes for crystals to form, how large they are, if and how they grow or aggregrate with time. We will also measure if the particles are charged, and how this evolves with time. Simultaneously, we investigate the crystal structure of the particles formed: are they amorphous (glass-like) or crystalline? Which crystal structure and does this remain constant with time? We will also visualise the sizes and shapes of the particles. If we unravel how sizes, shapes and crystallinity change with the ratio of their building blocks, we will generate a better “dictionary” for reading mineral textures in the geological archive: how were which mineral textures formed, so what were the environmental conditions at the time of mineral formation? We will then also provide new ways to tailor crystal formation for geo-enginering and industrial/pharamceutical purposes.
Besides laboratory work, we will simulate particle characteristics and formation processes. With these simulation results, we will obtain information at the molecular scale. In this way, we will derive charged-nuclei stability and surrounding water properties. The results will be combined into a new crystal nucleation theory, which can be used to predict or optimatize crystal formation processes in natural and engineered environments.
My research will have a three-fold impact. Firstly, new insights on nucleation and nuclei ripening pathways will lead to new interpretations of biogeological observations and geological textures. The shape, size, self-ordering and transformation of crystals formed in Earth surface environments are often used to unravel the conditions and relative timing of crystal formation, and as a proxy for paleo-environmental conditions. Moreover, there is a continued pursuit to understand and mimic the mechanisms behind mineral formation by organisms. In all of these cases, real-world observations are related to knowledge obtained from experiments performed at unnatural ionic ratios and theories based on condensation of uncharged droplets. The new CRYSTAL CLEAR insights will enhance our fundamental understanding of why, how and how fast crystals precipitate from natural solutions, and lead to new interpretations of geological textures and biogeological observations.
Secondly, major challenges in the field of crystal engineering are to guide or prevent nucleation and growth. Despite the large body of research on how to tailor crystal nucleation and growth in order to guide crystal size, structure, morphology and other characteristics , one powerful, additive-free tool has remained largely unexplored: the solution’s ionic ratio. My research will provide this new tool. Therefore, the outcome will lead to an enticing number of new geoengineering options. To illustrate this with a few examples: (i) optimizing calcite nucleation on substrates in descaling columns without the need for additional chemicals, will lead to more sustainable drinking water production techniques; (ii) keeping larger numbers of smaller nuclei in suspension along a longer flow path in the subsurface can greatly enhance various subsurface remediation, stabilization and CO2 sequestration methods; (iii) selecting critical nucleus size, shape and mineralogy without the need for additives will improve pharmaceutical production strategies.
And yes, proving that crystal nucleation mechanisms and rates depend upon ionic ratio will uproot general nucleation theory. Classical nucleation theory has always related rate only to degree of supersaturation (and seed surface area). My project will radically improve predictions of crystal formation rates and mechanisms. In this sense the results from the proposed research will be highly innovative on a very fundamental level, with ground-breaking implications throughout materials chemistry and engineering, a true paradigm shift.
Secondly, major challenges in the field of crystal engineering are to guide or prevent nucleation and growth. Despite the large body of research on how to tailor crystal nucleation and growth in order to guide crystal size, structure, morphology and other characteristics , one powerful, additive-free tool has remained largely unexplored: the solution’s ionic ratio. My research will provide this new tool. Therefore, the outcome will lead to an enticing number of new geoengineering options. To illustrate this with a few examples: (i) optimizing calcite nucleation on substrates in descaling columns without the need for additional chemicals, will lead to more sustainable drinking water production techniques; (ii) keeping larger numbers of smaller nuclei in suspension along a longer flow path in the subsurface can greatly enhance various subsurface remediation, stabilization and CO2 sequestration methods; (iii) selecting critical nucleus size, shape and mineralogy without the need for additives will improve pharmaceutical production strategies.
And yes, proving that crystal nucleation mechanisms and rates depend upon ionic ratio will uproot general nucleation theory. Classical nucleation theory has always related rate only to degree of supersaturation (and seed surface area). My project will radically improve predictions of crystal formation rates and mechanisms. In this sense the results from the proposed research will be highly innovative on a very fundamental level, with ground-breaking implications throughout materials chemistry and engineering, a true paradigm shift.