Semester of Graduation

Spring, 2022


Master of Science in Chemical Engineering (MSChE)


Chemical Engineering

Document Type



Nanotechnology has become an advanced tool for manufacturing materials of the future. As the size of a material is reduced to a nanoscale, its surface area to volume ratio increases drastically, and its surface property becomes size dependent. This allows scientists to make use of unique properties that nanomaterials have to offer to create novel materials that otherwise could not have been achieved in meter-scale materials. As more industrial companies have planned to incorporate different types of nanomaterials into their products, it is undeniable that some of these nanomaterials will be released to the environment. Such possibility has led to a controversial discussion concerning the impacts of nanoparticles to the environment among the public.

Stable nanoparticles are usually synthesized and stored under a strictly controlled condition. When nanoparticles are released in uncontrollable conditions such as the environment, they are very likely to become destabilized and form aggregates. Heteroaggregates are aggregates that contain two or more nanoparticle species. Synthetic nanoparticles released from manufacturing sites have a high chance of encountering naturally occurring colloids and forming heteroaggregates. However, predicting the fate of heteroaggregation in the environment remains puzzling due to the large variety of possible combinations of different types of nanoparticles.

Most of the nanoparticles currently used in industry are inorganic, which often are hazardous. In recent years, researchers have been trying to utilize biocompatible materials to synthesize green nanoparticles with the hope of creating safer novel nanomaterials. Lignin and zein nanoparticles are environmentally friendly nanomaterials; thus, they serve as ideal alternatives. Nevertheless, a detailed investigation exploring their stabilities and aggregation behaviors must be conducted before integrating them into an industrial-scale production. In this work, heteroaggregation of lignin and zein nanoparticles is studied. The results indicate that pH, relative size, and concentration of particles of each species directly influence the formation and structure of the heteroaggregates. The effects of heteroaggregation on an oil-water interface is also investigated. Large aggregates are found to produce a stable interface due to the formation of an interfacial film.

Committee Chair

Bharti, Bhuvnesh