# Enhanced control and production rates for a green continuous flow synthesis of magnetite nanoparticles: a comparative study of ethylenediamine additives

## TL;DR

This paper presents a green, scalable method for making magnetite nanoparticles using ethylenediamine additives in continuous flow, achieving high production rates and better control over particle shape.

## Contribution

The study introduces a continuous static mixing method with ethylenediamine additives that achieves a fivefold increase in production rate compared to previous methods.

## Key findings

- The continuous static mixing method achieved a theoretical production rate of up to 311 g per day.
- All five ethylenediamine additives improved octahedral particle morphology compared to the control.
- TEPA showed the greatest morphological control and was identified as a standout additive.

## Abstract

Scalable synthesis of precise magnetite nanoparticles (MNPs) with controlled properties remains a key challenge for applications in biomedical technologies, data storage, and environmental remediation. Bioinspired additive-driven methods offer greener, tunable synthesis routes, but often suffer from low production rates and limited scalability. Here we demonstrate that our green co-precipitation synthesis with ethylenediamine additives, using continuous static mixing, offers exceptional particle control along with a staggering theoretical production rate of up to 311 g per day, representing a fivefold increase over previously reported methods. This study presents a comprehensive comparison of five ethylenediamine-based additives — EDA, DETA, TETA, TEPA, and PEHA — across three systems: batch, millifluidic, and continuous static mixing. All five additives robustly enhanced octahedral particle morphology (38–84% faceted), compared to the control (no additive, 32% faceted), with a longer chain additive showing the greatest morphological control. These results suggest favourable binding of ethylenediamines to the [111] face of magnetite. This inherently scalable system offers a viable path to industrial-scale, shape-tuned MNP production. TEPA emerged as a standout additive, later refined in a Design of Experiments (DoE) study. While that study focused on a single system, our broader screening establishes critical parameters across additives and synthesis modes, laying the foundation for future optimisation of green, scalable MNP synthesis.

Ethylenediamine additives, particularly TEPA, in continuous flow synthesis enhances magnetite nanoparticles formation, realising scalable, sustainable production of green nanomaterials.