Liquids

Arid zones, such as the MENA regions and the Sahara countries, are experiencing significant water stress. To address this global challenge, desalination technologies provide a crucial solution, particularly the reverse osmosis (RO) technique, which is widely used to treat Seawater or Brackish water. Mauritania is among the countries facing a scarcity of potable water resources and relies on desalination technologies to meet its water demand. In this work, a numerical and experimental study was carried out on the functional and productive parameters of the Nouadhibou desalination plant in Mauritania using MATLAB/Simulink (R2016a). The study considered two operating scenarios: with and without the energy recovery unit. The objective of this paper is to perform an analytical study of the operating procedures of the Nouadhibou RO desalination plant by varying several parameters, such as the pressure exchanger, and the feed water mixing ratio in the pressure exchanger unit, etc., in order to determine the system’s optimal operating point. This paper analyzes the system’s performance under different conditions, including recovery rate, feed water temperature, and PEX splitter ratio. In Case No. 1 (without a pressure recovery unit), and with a recovery rate of 20%, doubling the plant’s productivity from 400 to 800 m³/d requires 400 kW of power. In contrast, in Case No. 2 (with a pressure recovery unit), achieving the same productivity requires only 100 kW, with a 75% of energy saving. When the desalination plant operates at a productivity of 400 m³/d@40%, the SPC decreases from 6 kWh/m³ (Case No. 1) to 2.7 kWh/m³ (Case No. 2), resulting in a 55% specific power consumption saving. The results also indicate that power consumption increases with both feed water temperature and PEX splitter ratio, while variations in these parameters have a negligible effect on permeate salinity.

Over the past two decades, terahertz (THz) spectroscopy has demonstrated remarkable potential for the investigation of liquids, including studies of living organisms and biological components in their natural, aqueous environments. The main advantages of THz radiation lie in its ability to interact with collective and low-energy vibrational modes of macromolecules and microorganisms, while being non-harmful due to the low photon energy involved. These characteristics make THz spectroscopy particularly valuable for research in liquids compared to other well-established techniques such as Raman and infrared spectroscopy. In this study, we offer a concise overview and comparison of two case studies from our earlier publications, highlighting how Ultrabroadband THz spectroscopy and Intense THz Spectroscopy serve as complementary methods for advancing research in liquids. Ultrabroadband THz spectroscopy enables simultaneous probing of both intermolecular and intramolecular interactions in a single experiment. On the other hand, intense THz spectroscopy greatly simplifies the determination of the optical constants of liquid solutions, eliminating the need for additional assumptions or prior knowledge. Moreover, it offers high sensitivity, allowing the detection of dilute solutions and subtle spectral variations. Currently, these two techniques typically rely on different THz sources, as achieving both broadband coverage and high intensity in a single setup remains challenging. In fact, the experimental results reviewed here were obtained at two different times and within two distinct scientific collaborations. In particular, the intense source was accessed through a collaboration with Prof. Novelli at Ruhr University in Bochum. Integrating both capabilities into a single apparatus would be highly desirable. Therefore, we also present a theoretical investigation of a novel experimental approach that could enable combined ultrabroadband and intense THz spectroscopy, merging the strengths of both methods.

In this article, we discuss the relationship and transition between self- and Fick diffusion coefficients in continuous implicit solvents across different particle densities. By applying the established expressions for self-diffusion and Fick diffusion coefficients in binary solutions, we analyze how the local environment influences diffusion through thermodynamic factors, which can be readily evaluated within the framework of Kirkwood–Buff (KB) theory. These thermodynamic factors, originally defined as derivatives of thermodynamic activity, vary with changes in local particle densities, particularly in the presence of aggregation effects. Consequently, the transition from self- to Fick diffusion coefficients can be understood as a reflection of variations in these thermodynamic factors. Langevin Dynamics simulations at low number densities show excellent agreement with the analytical expressions derived. Overall, our findings provide deeper insight into how local structural environments shape particle dynamics, clarifying the connection between KB theory and the transition from self- to Fick diffusion coefficients.