TY  - JOUR
A1  - Hartwig, Anne
A1  - Hass, Roland
T1  - Monitoring lactose crystallization at industrially relevant concentrations by photon density wave spectroscopy
JF  - Chemical engineering & technology
N2  - Lactose is of great industrial importance and its production includes the cooling crystallization from highly concentrated solutions. Monitoring the crystallization process is essential to ensure reproducible product quality. Photon density wave (PDW) spectroscopy enables in-line monitoring of highly concentrated processes in liquid dispersions. It was applied to the determination of the solubility and nucleation points of lactose monohydrate in water, sizing of lactose crystals, and to dissolution as well as crystallization monitoring. Other process analytical technologies (focused-beam reflectance measurement, particle vision and measurement) were used as reference, and the comparison indicates that PDW spectroscopy is very robust against probe fouling and is, thus, a useful tool for monitoring crystallization processes in concentrated suspensions.
KW  - In-line monitoring
KW  - Lactose
KW  - Light scattering
KW  - Photon density wave spectroscopy
KW  - Process analytical technology
Y1  - 2018
U6  - https://doi.org/10.1002/ceat.201700685
SN  - 0930-7516
SN  - 1521-4125
VL  - 41
IS  - 6
SP  - 1139
EP  - 1146
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Kutlug, Oezgür
A1  - Hass, Roland
A1  - Reck, Stephan
A1  - Hartwig, Andreas
T1  - Inline characterization of dispersion formation of a solvent-borne acrylic copolymer by Photon Density Wave spectroscopy
JF  - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects
N2  - Most investigations on phase inversion (PI) of resins upon addition of water have been carried out by dynamic light scattering (DLS), torque, and viscosity measurements. The main problem, however, is analytic discontinuity due to sample removal and a changing matrix due to dilution during the preparation of the aqueous resin dispersions. This work presents Photon Density Wave (PDW) spectroscopy as a tool for the inline characterization of the acetone process for an acrylic copolymer with high acrylic acid (AA) content. PDW spectroscopy revealed different trends for optical properties compared to torque during water feed. Also the absence of PI due to dissolution of copolymer in the solvent/water mixture is observed by PDW spectroscopy. PI for the investigated copolymer did not occour during water feed but during removal of solvent. Different feeding rates of water gave similar trends while a change in temperature and degree of AA neutralization led to changes in optical properties and torque. Thermal processing showed that the optical properties of mixtures prior and after removal of solvent were completely different caused by changes of solubility.
KW  - Acetone process
KW  - Dispersion
KW  - Photon Density Wave spectroscopy
KW  - Radical polymerization
KW  - Torque
KW  - Turbid media
Y1  - 2018
U6  - https://doi.org/10.1016/j.colsurfa.2018.08.011
SN  - 0927-7757
SN  - 1873-4359
VL  - 556
SP  - 113
EP  - 119
PB  - Elsevier
CY  - Amsterdam
ER  -