## 4 Conclusions and Outlook  
This study presents a simple and cost-efficient synthesis protocol, preserving the outstanding structural and electrical properties of carbon nanotubes during monolith synthesis and leading to stable and free-standing monoliths. Moreover, our work combines a broad material characterization of the synthesized monoliths with a subsequent investigation of interfacial effects occurring on the monoliths' surface, as well as an integrated electrosorption study. Thus, it paves the way towards a future application of monolithic CNT electrodes in an electrochemically driven separation process. For the stability of the synthesized monoliths, we determined the dispersion and gelation of the particles by ultrasonication during the synthesis process to be a key factor. Thus, ultrasonic treatment led tow strong gelation as drying in a heating chamber further stabilized the CNT network. We utilized untreated and mildly oxidized CNTs for monolith synthesis. Both materials enable the formation of stable monoliths with a comparable specific surface area. However, by using oxidized CNTs the conductivity of the monoliths  
Figure 9: Potential-controlled adsorption and release experiments for 5 mM maleic acid at pH 7 onto untreated (**a**) and oxidized (**b**) CNT-K monoliths. A potential of +500 mV for the adsorption and \(-\)500 mV for the desorption phase was applied for all experiments. Potentials were applied for 15 min during adsorption and release phase. could be strongly increased, indicating a more homogenous and pronounced particle network. Upon electrochemical characterization, the presence of capacitive and faradaic currents could be determined for both materials. However, pronounced faradaic currents were detected with oxidized monoliths, leading to an overall stronger current response. The potential-controlled adsorption of maleic acid was investigated as a proof of concept for an electrosorption process on CNT monoliths. Untreated and oxidized monoliths showed electrosorption behavior. While the adsorption capacity could be improved through oxidation, strong heterogeneous interactions still complicate a potential-triggered release of the model analyte. In this respect, the utilization of electro-active composites might be a possible way to control the reversible electrosorption onto CNT monoliths. Furthermore, the interfacial interactions guiding the reversible electrosorption of organic molecules should be further examined. With the goal of developing a potential-controlled process for biotechnological separations, we continue working on a preparative setup for the targeted electrosorption onto CNT monolith electrodes. The following are available online at [[https://www.mdpi.com/article/10](https://www.mdpi.com/article/10)]([https://www.mdpi.com/article/10](https://www.mdpi.com/article/10)) 3390/app11209390/s1, Figure S1: Test rig for conductivity measurements on cylindrical monoliths. Figure S2: Electrode contacting and test rig for potential-controlled adsorption experiments. Figure S3: Agglomerates of CNTs after oxidative and ultrasonic treatment in DI-Water and SDBS. Figure S4: FTIR spectra of untreated and oxidized CNT-K particles. Figure S5: Mechanical strength of cylindrical and planar monoliths. [PERSON], [PERSON] and [PERSON] designed the project, [PERSON], [PERSON], [PERSON], [PERSON], performed the experiments. All authors assisted in evaluating the results. [PERSON] wrote the manuscript. [PERSON], [PERSON] and [PERSON] assisted in reviewing and editing the manuscript. Financial acquisition and project administration by [PERSON] and [PERSON]. All authors have read and agreed to the published version of the manuscript. The research was funded by the Federal Ministry of Education and Research under the name S3 kapel (grant number 13 XP5038A). This work was supported by the Technical University of Munich (TUM) through the TUM Open Access Publishing Fund. Not applicable.