University of Sheffield researchers use Radleys Reactor-Ready to support process understanding for bioinspired silica manufacturing

Siddharth Pathwardhan from University of Sheffield stood next to Reactor-Ready Flex

Introduction

High-value nanomaterials have enormous potential across applications including energy, medicine, environmental remediation, catalysis and advanced materials. However, translating promising laboratory discoveries into scalable, sustainable manufacturing processes remains a significant challenge.

For Professor Siddharth Patwardhan and his team at the University of Sheffield, this challenge sits at the heart of their research. Based in the Department of Chemical and Biological Engineering, the Green Nanomaterials Research Group is developing new ways to manufacture functional nanomaterials, with a particular focus on bioinspired silica.

Silica is already manufactured globally at large scale, with established high-volume grades used in everyday applications such as toothpaste, tyres and footwear. High-value porous silicas, by contrast, can offer controlled surface area, pore size, surface chemistry and functionality, making them attractive for more specialised applications such as environmental remediation, catalysis, biomedical technologies and energy storage.

The challenge is that many high-value nanomaterials are difficult to make sustainably, economically and at scale. Conventional approaches can require high-purity starting materials, specialist equipment, multiple processing steps, high energy input, large volumes of water, toxic reagents or intensive downstream purification. These factors can make a material scientifically interesting, but difficult to translate into practical manufacture.

“Every time we’re looking at the discovery stage of a material, we need to look at performance, cost, environment and scale.”

Bioinspired silica: a greener route to functional materials

The team’s work focuses on bioinspired silica synthesis, an approach inspired by the way natural systems produce silica under mild conditions.

Rather than relying on harsh processing conditions, bioinspired silica can be produced in mild aqueous conditions, using low temperatures and fast reaction times. This offers a potentially more sustainable route to functional silica materials with controlled properties.

Siddharth described the approach as learning from biology, understanding the process in the laboratory, and then using that knowledge to support scale-up. The aim was to develop low-temperature, neutral pH, water-based reactions, then understand how they can be scaled.

This combination of chemistry and engineering is central to the group’s approach. Siddharth’s perspective sits between materials chemistry and chemical engineering: understanding the fundamental chemistry of material formation, while also considering how a process might eventually be manufactured.

That means looking at multiple factors simultaneously, including performance, cost, environmental impact and scalability. It also means identifying potential process bottlenecks early, before a material reaches the point where scale-up becomes too expensive or technically difficult.

Why mixing matters in silica scale-up

One of the key challenges in scaling bioinspired silica synthesis is understanding the role of mixing.

In these systems, mixing is not just a practical detail. It can directly influence how the reaction proceeds and, ultimately, the properties of the silica produced. Parameters such as feed location, feed rate and stirring speed can affect local pH, reaction progress, particle formation, pore size distribution and product consistency.

This is especially important for bioinspired silica because the reaction involves multiple formation stages. If mixing and reaction timescales overlap, then the way reagents are added, dispersed and homogenised inside the reactor can influence product attributes.

To investigate this, Siddharth’s team published a study titled A Novel Method for Understanding the Mixing Mechanisms to Enable Sustainable Manufacturing of Bioinspired Silica (ACS Eng. Au 2023, 3, 1, 17–27, https://doi.org/10.1021/acsengineeringau.2c00028). The work explored how mixing affects the formation of bioinspired silica and how this knowledge could support more informed scale-up studies.

The study used a 1 L Radleys Reactor-Ready setup as part of the experimental workflow. The team investigated how stirring speed and acid feed location affected the reaction, using a pH-responsive colour change and high-speed imaging to map mixing behaviour inside the vessel.

Using Reactor-Ready for lab-scale process understanding

For the mixing study, the team used Reactor-Ready as a controlled lab-scale stirred tank reactor. The system allowed them to vary key process parameters, including stirring speed and feed location, while monitoring how these changes affected mixing and silica formation.

The reaction involved a premixed aqueous solution containing sodium silicate and a bioinspired additive. Acid was then added to trigger the reaction, with a pH indicator used to monitor reaction progress and spatial mixing. The published work explains that an unbaffled 1 L stirred tank reactor was used as a model system, with the aim of focusing on understanding mixing effects rather than optimising the reactor setup itself.

High-speed camera footage was analysed by converting the reactor images into grids. Each grid was assigned a colour value, which was then related to pH. This enabled the team to create pH maps, visualise mixing behaviour and calculate the degree of mixing across the vessel.

“The pH tells us both the homogeneity of the fluid and the progress of reaction, and from that we can get pH maps, which tell us the degree of mixing.”

By combining image analysis with material characterisation, the researchers were able to study how mixing conditions affected particle size, pore structure, yield, conversion and intermediates. This allowed them to develop an empirical correlation between mixing time and Reynolds number, providing a scale-independent relationship that could help guide future scale-up studies for this system.

The published paper concludes that the method enabled the team to obtain spatial and temporal information on mixing and develop a new correlation between mixing time and Reynolds number for bioinspired silica synthesis. It also notes that future work will focus on understanding spatial and temporal mixing in more detail, measuring kinetics and using computational modelling to develop scale-up rules.

Siddharth Pathwardhan's large scale reactor at the University of Sheffield

From 1 L and 5 L studies to larger-scale development

The Reactor-Ready work formed part of a wider scale-up journey within Siddharth’s group.

The team has used Radleys reactors at both 1 L and 5 L scale for process development, quality by design work and the generation of material for testing. Having these systems available has been valuable when engaging with industrial partners, where gram-scale material is often needed for early evaluation.

“Having the one and five litre reactors was very handy.”

The group’s work has since moved beyond small-scale laboratory studies. In addition to 1 L and 5 L reactor work, Siddharth described the development of handmade 40 L equipment, plug flow reactor systems and a custom designed 300 L pilot-scale reactor system (see more details at https://amododesign.com/an-aeropress-for-chemical-engineering/).

This progression reflects one of the central challenges in commercialising advanced materials: small samples may be enough for basic characterisation, but larger quantities are often needed for meaningful performance testing and industry validation.

Industrial partners may be able to analyse a few grams of material, but testing performance in realistic rigs or applications often requires kilogram-scale batches. Siddharth explained that this need for larger quantities had been a key barrier to market validation, even when the route to market and commercialisation plan were in place.

Designing processes with manufacturing in mind

A key theme in Siddharth’s research is simplicity. The goal is to design processes that are not only effective in the laboratory, but practical for future manufacturing.

For bioinspired silica, this means avoiding unnecessary complexity wherever possible. The team is working towards processes that do not require inert conditions, complex stepwise additions or long waiting periods between stages.

“The aim is to make the process as simple as possible to operate at scale.”

This simplicity is important for both sustainability and commercialisation. Processes that are easier to operate, easier to control and easier to scale are more likely to be adopted outside the laboratory.

The team has also considered downstream processing and purification. In the discussion with Radleys, Siddharth noted that, for some of the silica materials, purification can involve simply washing with water or under slightly acidic conditions.

Commercial translation and AmpliSi

Siddharth’s broader work also reflects a strong interest in translating sustainable materials research beyond the laboratory. He is Co-founder and Chief Scientific Advisor of AmpliSi, a spin-out company focused on commercialising advanced silicon-based materials for battery anodes.

While the Reactor-Ready mixing study is a specific piece of academic research, it sits within a wider programme of work concerned with making high-value materials more scalable, sustainable and commercially relevant.

Siddharth discussed potential markets for high-value mesoporous silica, including longer-term opportunities in drug delivery and nearer-term applications in environmental pollution control, particularly the removal of pollutants from water.

For Siddharth’s team, this connection between fundamental science, process understanding and market need is critical. High-value materials will only make an impact if they can be produced in a form, quantity and cost profile that industry can use.

Supporting the journey from research to scale-up

The University of Sheffield’s work demonstrates how lab-scale reactor studies can play an important role in sustainable process development.

By using Reactor-Ready to investigate mixing effects at 1 L scale, Siddharth’s team were able to connect reaction conditions with material properties and generate insight that can support future scale-up studies. The wider use of 1 L and 5 L Radleys reactors has also supported process development and material generation for further testing.

For researchers working on complex materials, this flexibility is valuable. Reactor-Ready provides a practical lab-scale platform for studying reaction parameters, testing process conditions and generating material, while supporting the transition from small-scale discovery towards larger-scale process development.

As demand grows for sustainable, high-performance materials, this type of process understanding will become increasingly important. For Siddharth and his team, the aim is clear: to develop materials that are not only high-performing, but also scalable, sustainable and commercially relevant.

Find out more

Radleys Reactor-Ready systems are designed to support flexible lab-scale reaction development, process optimisation and scale-up studies.

Explore the Reactor-Ready range: https://www.radleys.com/range/jacketed-lab-reactors/

References and notes:

This work was supported by EPSRC funding, especially via a Fellowship in Manufacturing (Grant reference No. EP/R025983/1).

Pilling, R.; Patwardhan, S. V. Recent Advances in Enabling Green Manufacture of Functional Nanomaterials: A Case Study of Bioinspired Silica. Acs Sustainable Chemistry & Engineering 2022, 10 (37), 12048.

Baba, Y. D.; Chiacchia, M.; Patwardhan, S. V. A Novel Method for Understanding the Mixing Mechanisms to Enable Sustainable Manufacturing of Bioinspired Silica. Acs Engineering Au 2022, 3 (1), 17.

Manning, J. R. H.; Brambila, C.; Rishi, K.; Beaucage, G.; Davies, G. L.; Patwardhan, S. V. Quality-by-Design Approach to Process Intensification of Bioinspired Silica Synthesis. Acs Sustainable Chemistry & Engineering 2024, 12 (12), 4900.

Pilling, R.; Coles, S. R.; Knecht, M. R.; Patwardhan, S. V. Multi-criteria discovery, design and manufacturing to realise nanomaterial potential. Communications Engineering 2023, 2 (1), 78.