Controlled Synthesis of Smaller than 100 nm Lignin Nanoparticles in a Furnace Aerosol Reactor

Abstract

Lignin, a constituent of biomass, is a byproduct waste of the pulp and paper industry that may have several potential applications in nanoparticle form. Conventional synthesis of lignin nanoparticles (LNPs) involves physicochemical batch and multistep processes. We report here a continuous and single-step process for the synthesis of LNPs in a furnace aerosol reactor (FuAR) starting from bulk powders with minimal use of solvents. The synthesized LNPs were analyzed for their size distribution and functional group composition. Based on the changes in functional groups, the maximum temperature in the FuAR for obtaining LNPs without significant chemical degradation was found to be around 300 °C at a residence time of 5.8 s. The as-produced LNPs had a geometric mean diameter between 50 and 68 nm. Furthermore, the bulk and as-synthesized LNPs were tested for UV protection applications. The observed improvement in UV protection with a decrease in lignin particle size is systematically investigated using the optical absorption parameter, which provides a quantitative correlation for the effect of lignin particle size and mass concentration on UV protection performance. Overall, this study contributes to advancing lignin valorization by demonstrating the synthesis of LNPs using the scalable FuAR method and providing a novel quantitative correlation for the design of highperformance lignin-based UV protection materials.

The use of phages for the biosynthesis of metal nanoparticles and their biological applications: A review

“…Nanoparticles have many activities, including antimicrobial, anti‐inflammatory, anti‐tumour, antioxidant, drug manufacturing, etc 3–5 . Nanoparticles are particles smaller than 100 nm that are synthesized in different ways 6 …”

Reuse of Lignin to Synthesize High Surface Area Carbon Nanoparticles for Supercapacitors Using a Continuous and Single-Step Aerosol Method

“…Synthesis techniques based on aerosol processes can potentially address the limitations of conventional porous carbon synthesis methods. Aerosol-based techniques are widely applied for controlled and scalable synthesis of a wide range of nanomaterials including titania pigments, carbon black, and fumed silica. − Commonly used aerosol techniques use flame aerosol reactor, furnace aerosol reactor (FuAR), and electrospray. , The FuAR is especially known for enabling precise control over a wide range of temperatures and residence times. , As the process temperature and residence time are expected to have a key impact on the properties of carbon materials synthesized from lignin, FuARs could be of significant advantage for this application. FuAR operation mainly involves three key processes: first, the precursor solution is nebulized using pressurized gas to generate droplets; second, the finer fraction of droplets is sent through a tubular furnace for thermochemical conversion (pyrolysis); and finally, solid nanoparticles exiting the reactor are separated from a gas stream using a membrane.…”

“…21,22 The FuAR is especially known for enabling precise control over a wide range of temperatures and residence times. 22,23 As the process temperature and residence time are expected to have a key impact on the properties of carbon materials synthesized from lignin, FuARs could be of significant advantage for this application. FuAR operation mainly involves three key processes: first, the precursor solution is nebulized using pressurized gas to generate droplets; second, the finer fraction of droplets is sent through a tubular furnace for thermochemical conversion (pyrolysis); and finally, solid nanoparticles exiting the reactor are separated from a gas stream using a membrane.…”