Inline and Online Process Analytical Technology with a Focus on Optical Spectroscopy

Abstract

Process analytical technology (PAT) is a cross‐sectional technology and thus essential for future smart production. While in the past decades, the focus of process optimization strategies was on increasing efficiency, in the future, the focus will be on the sustainability of a production and its products. In addition, products will be increasingly personalized in order to match the property profile exactly to the intended use. PAT is able to provide context‐sensitive information at the molecular level for process control. Spectroscopic sensors can determine inline and simultaneously both the chemical composition and its sub‐microscopic morphology. The article will focus on the optical spectroscopy and therefore starts with a brief introduction on the basic concepts of molecular spectroscopy. In addition, the particularities of measuring liquids, surfaces, or particulate systems in PAT applications are described. This should enable the reader to select the appropriate method for the specific problem. Many examples from everyday industrial practice illustrate the applications. The areas covered are the manufacturing industry, process and pharmaceutical industry, food industry, as well as biotechnology and medical technology. Future will show that PAT is especially important for applications in the field of medicine (point of care) circular economy (recycling, water–wastewater, etc.). It is important to emphasize that sustainability in industrial production can only be successful with an inter‐ and transdisciplinary close exchange between the different disciplines.

Continuous sonochemical nanotransformation of lignin – Process design and control

“…Nevertheless, DLS and optical spectroscopy could be of great use for at-line or in-line quality control to detect and follow trends in the evolution of product quality during processing. Often it will be sufficient to establish a so-called “golden batch” which defines the limits (e.g., process trajectories) in which the process should perform [29] . Thus, the objective of these experiments was to get insight into the structure and absolute particle size of the original lignin material and the lignin subjected to sonication.…”

“…In parallel, the costs of complex measurement technologies have been dramatically reduced, and advances in information technology make it possible to process large volumes of data in real time. Spectroscopic methods, in particular, are able to generate data with high information content in just a few fractions of a second, objectively reflecting the actual product state at the molecular level [29] .…”

“…Molecular spectroscopy is based on the interaction of electromagnetic radiation with particulate matter. The inelastic interaction (photon impact on a molecule) results in the transition of the molecule from a lower to a higher energy level (absorption spectroscopy), whereas the elastic interaction with particulate matter results in the scatter of the photon in different directions (ELS = elastic light spectroscopy, or Mie-backscatter spectroscopy) [29] . Both, elastic and inelastic interactions are wavelength dependent, and thus provide mostly superposed absorption and scatter spectra (labelled also as backscattering spectra).…”

“…To this end, methods of statistical design of experiments (DoE) allowing to assign both qualitatively and quantitatively “cause and effect” will be used. Optical spectroscopy together with complex multivariate data analysis will provide efficient inline quality control to generate knowledge from data on a molecular level and to visualize in-situ chemical and morphological changes in lignin during the nanotransformation process [29] .…”