Low-cost test rig for characterization of photocatalytic planar materials using photonically sized UV-A LED light sources.

In the presented studies, a system for the characterization of planar photocatalysts was developed and tested. In the system, reference substances can be studied online with regard to their degradability and adsorption on photocatalytic materials. In order to perform accurate calculations of the quantum and photon efficiency of the catalysts, the LED arrays used were adjusted in their spacing by simulations so that a homogeneous light field is imaged on the catalysts. The system was tested with respect to measurement accuracy and reproducibility and the photocatalytic degradation of methylene blue, methyl orange and rhodamine B was investigated. Exemplarily, the reaction kinetics, photolysis and adsorption on the tested photocatalysts were determined for these compounds and the calculation was presented in detail. The exact construction plans and circuits as well as the sensors and their programming are presented in detail and should encourage other scientists to replicate the experimental setup, since especially in the field of photocatalysis research, often the results of publications cannot be compared with each other.

Hybrid Ceramic Membranes for the Removal of Pharmaceuticals from Aqueous Solutions.

Layer-by-Layer (LbL) technology was used to coat alumina ceramic membranes with nanosized polyelectrolyte films. The polyelectrolyte chains form a network with nanopores on the ceramic surface and promote the rejection of small molecules such as pharmaceuticals, salts and industrial contaminants, which can otherwise not be eliminated using standard ultrafiltration methods. The properties and performance of newly developed hybrid membranes are in the focus of this investigation. The homogeneity of the applied coating layer was investigated by confocal fluorescence microscopy and scanning transmission electron microscopy (STEM). Properties such as permeability, bubble point, pore size distribution and Zeta potential were determined for both pristine and LbL coated membranes using various laboratory tests. Subsequently, a thorough comparison was drawn. The charging behavior at solid-liquid interface was characterized using streaming potential techniques. The retention potential was monitored by subjecting widely used pharmaceuticals such as diclofenac, ibuprofen and sulfamethoxazol. The results prove a successful elimination of pharmaceutical contaminants, up to 84% from drinking water, by applying a combination of polyelectrolyte multilayers and ceramic membranes.